U.S. patent application number 10/148808 was filed with the patent office on 2003-07-03 for information disk recording/reproducing device, and method for detecting vibration of information disk recording/reproducing device.
Invention is credited to Takahashi, Yorio.
Application Number | 20030123354 10/148808 |
Document ID | / |
Family ID | 18881930 |
Filed Date | 2003-07-03 |
United States Patent
Application |
20030123354 |
Kind Code |
A1 |
Takahashi, Yorio |
July 3, 2003 |
Information disk recording/reproducing device, and method for
detecting vibration of information disk recording/reproducing
device
Abstract
The present invention provides an information
disc-recording/playback apparatus which includes a track cross
detection means (112), a track cross direction detection means
(113), a rotation angle detection means (114), and a count means
(115), detects the track pitch of a disc, evaluates the vibration
amount, or vibration speed, or vibration acceleration considering
the track pitch of the disc, and determines a maximum rotation
speed that is lower than the allowable vibration amplitude,
vibration speed, or vibration acceleration of the information disc
recording/playback apparatus; as well as a vibration detection
method for the information disc recording/playback apparatus. This
information disc recording/playback apparatus can perform vibration
detection using a single threshold value that is independent of the
type of the disc, without using an acceleration sensor, and
further, the apparatus can accurately perform vibration detection
even when direction detection is difficult.
Inventors: |
Takahashi, Yorio; (Ehime,
JP) |
Correspondence
Address: |
WENDEROTH, LIND & PONACK, L.L.P.
2033 K STREET N. W.
SUITE 800
WASHINGTON
DC
20006-1021
US
|
Family ID: |
18881930 |
Appl. No.: |
10/148808 |
Filed: |
October 4, 2002 |
PCT Filed: |
November 14, 2001 |
PCT NO: |
PCT/JP01/09934 |
Current U.S.
Class: |
369/53.2 ;
369/53.18; 369/53.28; 369/53.3; G9B/19.014; G9B/19.017; G9B/19.046;
G9B/20.009 |
Current CPC
Class: |
G11B 19/06 20130101;
G11B 19/12 20130101; G11B 20/10 20130101; G11B 7/0946 20130101;
G11B 7/0953 20130101; G11B 2007/0006 20130101; G11B 19/28
20130101 |
Class at
Publication: |
369/53.2 ;
369/53.18; 369/53.3; 369/53.28 |
International
Class: |
G11B 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 24, 2001 |
JP |
2001-015366 |
Claims
1. An information disc recording/playback apparatus capable of
recording or playing at least two kinds of information discs having
different track pitches, on which information recording tracks are
formed spirally or concentrically, said apparatus comprising: a
disc rotation means for rotating the information disc at a
predetermined speed; a reading means for reading an information
signal from the disc; a drive means for driving the reading means
in the direction of the radius of the disc; a track pitch detection
means for detecting the track pitch of the information disc from
the information disc; a track cross detection means for generating
track cross signals on the basis of playback signals that are
generated when the reading means crosses the information tracks; a
count means for counting track cross pulses that are detected by
the track cross detection means, and outputting the count; and a
control means for determining a maximum rotation speed that is
lower than an allowable vibration amplitude of the information disc
recording/playback apparatus on the basis of the count and the
track pitch, or determining a maximum rotation speed that is lower
than an allowable vibration speed or vibration acceleration speed
of the information disc recording/playback apparatus on the basis
of the count, the track pitch, and the current disc rotation speed,
and controlling the disc rotation means so that the disc rotation
means rotates the information disc at a speed lower than the
allowable maximum rotation speed to record or reproduce data
in/from the disc.
2. An information disc recording/playback apparatus as defined in
claim 1 further comprising: a track cross direction detection means
for detecting a track cross direction indicating the direction in
which the reading means crosses the information tracks; a rotation
angle detection means for outputting rotation angle information of
the disc rotation means; and said count means for counting the
track cross pulses with signs, which are detected by the track
cross detection means, on the basis of the result of the detection
by the track cross direction detection means, and the rotation
angle information outputted from the rotation angle detection
means.
3. An information disc recording/playback apparatus as defined in
claim 1 further comprising: a track cross direction detection means
for detecting a track cross direction indicating the direction in
which the reading means crosses the information tracks; a track
cross speed detection means for detecting the frequency of the
track cross pulses; a rotation angle detection means for outputting
rotation angle information of the disc rotation means; and said
count means for counting the track cross pulses with signs, which
are detected by the track cross detection means, on the basis of
the result of the detection by the track cross direction detection
means and the rotation angle information outputted from the
rotation angle detection means, while detecting the track cross
direction by the track cross direction detection means when the
result of the detection by the track cross speed detection means
indicates that the track cross speed is lower than a predetermined
value, and counting the track cross pulses with signs, without
detecting the track cross direction by the track cross direction
detection means, on the basis of the track cross direction that has
just previously been detected by the track cross direction
detection means, when the result of the detection by the track
cross speed detection means indicates that the track cross speed
becomes higher than the predetermined value.
4. An information disc recording/playback apparatus capable of
recording or playing at least two kinds of information discs having
different track pitches, on which information recording tracks are
formed spirally or concentrically, said apparatus comprising: a
disc rotation means for rotating the information disc at a
predetermined speed; a reading means for reading an information
signal from the disc; a drive means for driving the reading means
in the direction of the radius of the disc; a track pitch detection
means for detecting the track pitch of the information disc from
the information disc; a track cross detection means for generating
track cross signals on the basis of playback signals that are
generated when the reading means crosses the information tracks; a
track cross direction detection means for detecting a track cross
direction indicating the direction in which the reading means
crosses the information tracks; a rotation angle detection means
for outputting rotation angle information of the disc rotation
means, which is divided into n areas for one rotation; a zero cross
area detection means for detecting two areas where the track cross
speed has a lowest value, from among the n areas; a count means for
counting track cross pulses with signs, which are detected by the
track cross detection means, on the basis of the result of the
detection by the track cross direction detection means and the
rotation angle information outputted from the rotation angle
detection means, while detecting the track cross direction by the
track cross direction detection means, in an area where the track
cross speed has the lowest value according to the result of the
detection by the zero cross area detection means, counting the
track cross pulses with signs, without detecting the track cross
direction by the track cross direction detection means, on the
basis of the track cross direction that has just previously been
detected by the track cross direction detection means, in an area
where the track cross speed does not have the lowest value
according to the result of the detection by the zero cross area
detection means, and outputting the count; and a control means for
determining a maximum rotation speed that is lower than an
allowable vibration amplitude of the information disc
recording/playback apparatus on the basis of the count and the
track pitch, or determining a maximum rotation speed that is lower
than an allowable vibration speed or vibration acceleration speed
of the information disc recording/playback apparatus on the basis
of the count, the track pitch, and the current disc rotation speed,
and controlling the disc rotation means so that the disc rotation
means rotates the information disc at a speed lower than the
allowable maximum rotation speed to record or reproduce data
in/from the disc.
5. An information disc recording/playback apparatus capable of
recording or playing at least two kinds of information discs having
different track pitches, on which information recording tracks are
formed spirally or concentrically, said apparatus comprising: a
disc rotation means for rotating the information disc at a
predetermined speed; a reading means for reading an information
signal from the disc; a drive means for driving the reading means
in the direction of the radius of the disc; a track pitch detection
means for detecting the track pitch of the information disc from
the information disc; a track cross detection means for generating
track cross signals on the basis of playback signals that are
generated when the reading means crosses the information tracks; a
track cross direction detection means for detecting a track cross
direction indicating the direction in which the reading means
crosses the information tracks; a rotation angle detection means
for outputting rotation angle information of the disc rotation
means, which is divided into n areas for one rotation; a zero cross
area detection means for detecting two areas where the track cross
speed has a lowest value, from among the n areas; a count means
including a first count means for counting track cross pulses with
signs, which are detected by the track cross detection means, on
the basis of the result of the detection by the track cross
direction detection means and the rotation angle information
outputted from the rotation angle detection means, and a second
count means for counting the track cross pulses detected by the
track cross detection means, without detecting the track cross
direction, on the basis of the rotation angle information outputted
from the rotation angle detection means, said count means for
obtaining a first count of the first count means when the drive
means is disabled and the information disc loaded on the disc
rotation means is rotated, obtaining a second count in which a sign
is added to the count of the second count means, on the basis of
the track cross direction which has just previously been detected
by the track cross direction detection means, when the drive means
is disabled and the information disc loaded on the disc rotation
means is rotated, selecting the first count in an area where the
track cross speed has the lowest value according to the result of
the detection by the zero cross area detection means, selecting the
second count in an area where the track cross speed does not have
the lowest value according to the result of the detection by the
zero cross area detection means, and counting the track cross
pulses for every rotation angle and outputting it; and a control
means for determining a maximum rotation speed that is lower than
an allowable vibration amplitude of the information disc
recording/playback apparatus on the basis of the counts and the
track pitch, or determining a maximum rotation speed that is lower
than an allowable vibration speed or vibration acceleration speed
of the information disc recording/playback apparatus on the basis
of the counts, the track pitch, and the current disc rotation
speed, and controlling the disc rotation means so that the disc
rotation means rotates the information disc at a speed lower than
the allowable maximum rotation speed to record or reproduce data
in/from the disc.
6. An information disc recording/playback apparatus as defined in
claim 4 or 5, wherein said rotation angle detection means divides
the rotation angle information of the disc rotation means into six
areas for each rotation, and outputs the divided information; and
said zero cross area detection means detects, as zero cross areas,
an area where the count of the count means has the smallest value,
and an area on a diagonal line with respect to the area.
7. An information disc recording/playback apparatus capable of
recording or playing at least two kinds of information discs having
different track pitches, on which information recording tracks are
formed spirally or concentrically, said apparatus comprising: a
disc rotation means for rotating the information disc at a
predetermined speed; a reading means for reading an information
signal from the disc; a drive means for driving the reading means
in the direction of the radius of the disc; a track pitch detection
means for detecting the track pitch of the information disc from
the information disc; a track cross detection means for generating
track cross signals on the basis of playback signals that are
generated when the reading means crosses the information tracks; a
count means for counting track cross pulses that are detected by
the track cross detection means, and outputting the count; and a
control means for using, as the count, a difference between the
track cross count that is obtained when the information disc is
rotated at a first rotation speed and at least one rotation speed
that is higher than the first rotation speed, and a count that is
obtained with the at least one rotation speed higher than the first
rotation speed, determining a maximum rotation speed that is lower
than an allowable vibration amplitude of the information disc
recording/playback apparatus on the basis of the count and the
track pitch, or determining a maximum rotation speed that is lower
than an allowable vibration speed or vibration acceleration speed
of the information disc recording/playback apparatus on the basis
of the count, the track pitch, and the current disc rotation speed,
and controlling the disc rotation means so that the disc rotation
means rotates the information disc at a speed lower than the
allowable maximum rotation speed to record or reproduce data
in/from the disc.
8. An information disc recording/playback apparatus as defined in
claim 7, wherein the first rotation speed is a sufficiently low
speed at which no vibration occurs between the information disc and
the reading means, and the track cross pulses due to the
eccentricities of the information disc and the disc rotation means
are counted.
9. An information disc recording/playback apparatus as defined in
claim 7, wherein said count means counts the track cross pulses at
the first rotation speed for a predetermined number of times, and
counts the track cross pulses with the at least one rotation speed
that is higher than the first rotation speed, for the predetermined
number of times; and said control means employs, as the count, an
average of counts for more than one time, which are selected from
among the counts obtained by the above-described repetition, or a
value in proportion to the average.
10. An information disc recording/playback apparatus as defined in
claim 7, wherein said rotation angle detection means outputs the
rotation angle information of the disc rotation means, which is
divided into six areas for one rotation; and when a difference
between the track cross count measured at the first rotation speed
with each of the six-divided rotation angles, and the track cross
count measured with the at least one rotation speed higher than the
first rotation speed is as follows:
DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5](when n>5, n=n
mod 6 (a remainder of n being divided by 6), the control means
determines a maximum rotation speed that is lower than the
allowable amplitude of the information disc recording/playback
apparatus, on the basis of a value in proportion to a vibration
amount 1 or a vibration amount 2, or a value in proportion to the
second power of the vibration amount 1 or the second power of the
vibration amount 2, and the track pitch, said vibration amounts 1
and 2 being represented as follows: 29 vibration amount 1 [ n ] = 2
3 | DAT [ n ] 2 + DAT [ n ] DAT [ n + 1 ] + DAT [ n + 1 ] 2 | (
Formula 1 ) vibration amount 2 [ n ] = 2 3 | DAT [ n ] 2 - DAT [ n
] DAT [ n + 2 ] + DAT [ n + 2 ] 2 | ( Formula 2 )
11. An information disc recording/playback apparatus as defined in
claim 10, wherein said control means determines a maximum rotation
speed that is lower than the allowable amplitude of the information
disc recording/playback apparatus, on the basis of a value in
proportion to an average of twelve vibration amounts 1 or vibration
amounts 2 which are calculated for n=0.about.5 according
to,(Formula 1) or (Formula 2), and the track pitch, or a value in
proportion to an average of m pieces of central values selected
from among the twelve vibration amounts 1 or vibration amounts 2,
and the track pitch, or a value in proportion to an average of m
pieces of central values selected from the second powers of the
twelve vibration amounts 1 or vibration amounts 2, and the track
pitch.
12. An information disc recording/playback apparatus as defined in
claim 7, wherein said rotation angle detection means divides the
rotation angle information of the disc rotation means into six
areas for one rotation, and outputs the divided rotation angle
information; and when a difference between the track cross count
which is obtained at the first rotation speed for each of the
six-divided rotation angles, and the track cross count which is
obtained with the at least one rotation speed higher than the first
rotation speed is represented by DAT[n]=DAT[0],DAT[1],DAT[2],DA-
T[3],DAT[4],DAT[5](when n>5, n=n mod 6 (a remainder of n being
divided by 6), and the rotation speed of the disc rotation means is
Vrpm[rpm], said control means determines a maximum rotation speed
that is lower than the allowable amplitude of the information disc
recording/playback apparatus, on the basis of a value in proportion
to a vibration speed 1 or a vibration speed 2, or a value in
proportion to the second power of the vibration speed 1 or the
second power of the vibration speed 2, and the track pitch, said
vibration speeds 1 and 2 being represented by 30 vibration speed 1
[ n ] = 2 V rpm 60 2 3 | DAT [ n ] 2 + DAT [ n ] DAT [ n + 1 ] +
DAT [ n + 1 ] 2 | ( Formula 3 ) vibration speed 2 [ n ] = 2 V rpm
60 2 3 | DAT [ n ] 2 - DAT [ n ] DAT [ n + 2 ] + DAT [ n + 2 ] 2 |
( Formula 4 )
13. An information disc recording/playback apparatus as defined in
claim 12, wherein said control means determines a maximum rotation
speed that is lower than the allowable amplitude of the information
disc recording/playback apparatus, on the basis of a value in
proportion to an average of twelve vibration speeds 1 or vibration
speeds 2 which are calculated for n=0.about.5 according to (Formula
3) and (Formula 4), respectively, and the track pitch, or a value
in proportion to an average of m pieces of central values selected
from the values of the twelve vibration speeds 1 or vibration
speeds 2, and the track pitch, or a value in proportion to an
average of m pieces of central values selected from the second
powers of the twelve vibration speeds 1 or the second powers of the
vibration speeds 2, and the track pitch.
14. An information disc recording/playback apparatus as defined in
claim 7, wherein said rotation angle detection means divides the
rotation angle information of the disc rotation means into six
areas for one rotation, and outputs the divided rotation angle
information; and when a difference between the track cross amount
which is measured at the first rotation speed for each of the
six-divided rotation angles, and the track cross amount which is
measured with the at least one rotation speed higher than the first
rotation speed is represented by DAT[n]=DAT[0],DAT[1],DAT[2],DA-
T[3],DAT[4],DAT[5](when n>5, n=n mod 6 (a remainder of n being
divided by 6), and the rotation speed of the disc rotation means is
Vrpm[rpm], said control means determines a maximum rotation speed
that is lower than the allowable amplitude of the information disc
recording/playback apparatus, on the basis of a value in proportion
to a vibration acceleration 1 or a vibration acceleration 2, or a
value in proportion to the second power of the vibration
acceleration 1 or the second power of the vibration acceleration 2,
and the track pitch, said vibration accelerations. 1 and 2 being
represented by 31 vibration acceleration 1 [ n ] = ( 2 V rpm 60 ) 2
2 3 DAT [ n ] 2 + DAT [ n ] DAT [ n + 1 ] + DAT [ n + 1 ] 2 (
Formula 5 ) vibration acceleration 2 [ n ] = ( 2 V rpm 60 ) 2 2 3
DAT [ n ] 2 - DAT [ n ] DAT [ n + 2 ] + DAT [ n + 2 ] 2 ( Formula 6
)
15. An information disc recording/playback apparatus as defined in
claim 14, wherein said control means determines a maximum rotation
speed that is lower than the allowable amplitude of the information
disc recording/playback apparatus, on the basis of a value in
proportion to an average of twelve vibration accelerations 1 or
vibration accelerations 2 which are calculated for n=0.about.5
according to (Formula 5) and (Formula 6), respectively, and the
track pitch, or a value in proportion to an average of m pieces of
central values selected from the values of the twelve vibration
accelerations 1 or vibration accelerations 2, and the track pitch,
or a value in proportion to an average of m pieces of central
values selected from the second powers of the twelve vibration
accelerations 1 or the second powers of the twelve vibration
accelerations 2, and the track pitch.
16. An information disc recording/playback apparatus as defined in
claim 1, wherein said track pitch detection means detects the type
of the loaded information disc, and selects a track pitch
corresponding to the detected disc type, with reference to a table
in which standard track pitches corresponding to the respective
types of the information discs are described.
17. An information disc recording/playback apparatus as defined in
claim 1 further comprising: a move distance detection means for
detecting the distance by which the reading means moves; and said
track pitch detection means for making the reading means move for a
predetermined period of time or by a predetermined distance when
the information disc is loaded, counting the number of tracks the
reading means crosses while it is moving, and detecting the track
pitch on the basis of the move distance and the track cross
count.
18. An information recording/playback apparatus as defined in claim
1, further comprising: a linear speed detection means for detecting
the linear speed of the information disc; a playback speed
detection means for detecting the current playback speed of the
information disc; and said track pitch detection means for
calculating the track pitch of the information disc, on the basis
of the detected type of the information disc, the linear speed of
the information disc detected by the linear speed detection means,
the playback speed detected at a predetermined rotation speed and a
predetermined address, the predetermined rotation speed, the
predetermined address, the innermost radius of data area which is
unique to the detected type of the disc, and the data rate when the
disc is played at the predetermined playback speed which is unique
to the type of the disc.
19. An information disc recording/playback apparatus capable of
recording or playing an information disc on which information
recording tracks are formed spirally or concentrically, said
apparatus comprising: a disc rotation means for rotating the
information disc at a predetermined speed; a reading means for
reading an information signal from the disc; a drive means for
driving the reading means in the direction of the radius of the
disc; a track cross detection means for generating track cross
pulses on the basis of playback signals that are generated when the
reading means crosses the information tracks; a variable filter
means for preventing counting of pulses whose widths are narrower
than a set value, among the track cross pulses; a count means for
counting the pulses outputted from the variable filter means; and a
control means for determining a maximum rotation speed that is
lower than an allowable number of track crosses of the information
disc recording/playback apparatus on the basis of the count, or
determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration of the
information disc recording/playback apparatus on the basis of the
count and the current disc rotation speed, and controlling the disc
rotation means so that the disc rotation means rotates the
information disc at a speed lower than the allowable maximum
rotation speed to record or reproduce data in/from the disc.
20. An information disc recording/playback apparatus as defined in
claim 19, further comprising: a track cross direction detection
means for detecting the track cross direction which indicates the
direction in which the reading means crosses the information
tracks; a rotation angle detection means for outputting rotation
angle information of the disc rotation means; and said count means
for counting the track cross pulses with signs, which are detected
by the track cross detection means, on the basis of the result of
the detection by the track cross direction detection means and the
rotation angle information outputted from the rotation angle
detection means.
21. An information disc recording/playback apparatus capable of
recording or playing an information disc on which information
recording tracks are formed spirally or concentrically, said
apparatus comprising: a disc rotation means for rotating the
information disc at a predetermined speed; a reading means for
reading an information signal from the disc; a drive means for
driving the reading means in the direction of the radius of the
disc; a track cross detection means for generating track cross
pulses on the basis of playback signals that are generated when the
reading means crosses the information tracks; a variable filter
means for preventing counting of pulses whose widths are narrower
than a set value, among the track cross pulses; a track cross
direction detection means for detecting the track cross direction
which indicates the direction in which the reading means crosses
the information tracks; a rotation angle detection means for
outputting rotation angle information of the disc rotation means; a
count means including a first count means for counting the track
cross pulses with signs, which are outputted from the filter means,
on the basis of the result of the detection by the track cross
direction detection means and the rotation angle information
outputted from the rotation angle detection means, and a second
count means for counting the track cross pulses outputted from the
filter means, without detecting the track cross direction, on the
basis of the rotation angle information outputted from the rotation
angle detection means, said count means for obtaining the count of
the first or second count means when an initial value of count is
set for setting an initial value of the variable filter means, a
value of the variable filter is set on the basis of the count and
the current rotation speed, the drive means is disabled, and the
information disc loaded on the disc rotation means is rotated at a
predetermined rotation speed, and repeating the process of
obtaining the count of the first or second count means when the
value of the variable filter is set and the information disc is
rotated at the predetermined speed, for a required number of times,
thereby obtaining the counts for more than one rotation; and a
control means for determining a maximum rotation speed that is
lower than an allowable number of track crosses of the information
disc recording/playback apparatus on the basis of the count, or
determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration of the
information disc recording/playback apparatus on the basis of the
count and the current disc rotation speed, and controlling the disc
rotation means so that the disc rotation means rotates the
information disc at a speed lower than the allowable maximum
rotation speed to record or reproduce data in/from the disc.
22. An information disc recording/playback apparatus as defined in
claim 21, wherein said count means obtains the count of the first
count means when the value of the variable filter is set on the
basis of the count and the current rotation speed, the drive means
is disabled, and the information disc loaded on the disc rotation
means is rotated at a predetermined rotation speed, and repeats the
process of obtaining the count of the first count means when the
information disc is rotated at the predetermined speed, for a
required number of times, thereby obtaining the counts for more
than one rotation.
23. An information disc recording/playback apparatus as defined in
claim 21 or 22, wherein when setting the value of the variable
filter on the basis of the count and the current rotation speed, if
the count is one obtained without detecting the track cross
direction, assuming that the total number of track crosses per
rotation is 4Tc, and the current rotation speed is Vrpm, a maximum
track cross speed is calculated by 32 maximum track cross speed = 2
V rpm 60 T c ( Formula 7 ) and, on the basis of the calculated
maximum track cross speed, the value of the variable filter is set,
and a minimum track count pulse width is set.
24. An information disc recording/playback apparatus as defined in
claim 21 or 22, wherein said rotation angle detection means divides
the rotation angle information of the disc rotation means into six
areas for one rotation and outputs the divided rotation angle
information, and when the count is one obtained when the track
cross direction is detected, the count at each of the six-divided
rotation angles is represented by
DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5](when n>5, n=n
mod 6 (a remainder of n being divided by 6), and the rotation speed
of the disc rotation means is Vrpm[rpm], a value in proportion to a
maximum track cross speed 1 or a maximum track cross speed 2 which
are represented as follows are calculated as a maximum track cross
speed, 33 maximum track cross speed 1 [ n ] = 2 V rpm 60 2 3 DAT [
n ] 2 + DAT [ n ] DAT [ n + 1 ] + DAT [ n + 1 ] 2 ( Formula 8 )
maximum track cross speed 2 [ n ] = 2 V rpm 60 2 3 DAT [ n ] 2 -
DAT [ n ] DAT [ n + 2 ] + DAT [ n + 2 ] 2 ( Formula 9 ) and a value
in proportion to an average of twelve maximum track cross speeds 1
or maximum track cross speeds 2 which are calculated for
n=0.about.5 according to (Formula 8) and (Formula 9), respectively,
or a value in proportion to an average of m pieces of central
values selected from the values of the twelve maximum track cross
speeds 1 or maximum track cross speeds 2, is employed as a maximum
track cross speed.
25. An information disc recording/playback apparatus as defined in
claim 24, wherein when the value of the variable filter is set on
the basis of the count and the current rotation speed, if the count
is one obtained when the track cross direction is detected, the
count at each of the six-divided rotation angles is represented by
DAT[n]=DAT[0],DAT[1],DAT[2]- ,DAT[3],DAT[4],DAT[5](when n>5, n=n
mod 6 (a remainder of n being divided by 6), and the rotation speed
of the disc rotation means is Vrpm[rpm], a maximum track cross
speed is calculated on the basis of the following formulae,
4T.sub.c=.vertline.DAT[0].vertline.+.vertline.DAT[1].-
vertline.+.vertline.DAT[2].vertline.+.vertline.DAT[3].vertline.+.vertline.-
DAT[4].vertline.+.vertline.DAT[5].vertline. (Formula 10) 34 maximum
track cross speed = 2 V rpm 60 T c 1 cos 6 = 2 V rpm 60 T c 2 3 (
Formula 11 ) and, on the basis of the maximum track cross speed so
calculated, the value of the variable filter is set, and a minimum
track count pulse width is set.
26. An information disc recording/playback apparatus as defined in
claim 19, wherein when setting the maximum rotation speed of the
information disc recording/playback apparatus, the control means
employs, as the count, a difference between the track cross count
that is obtained when the information disc is rotated at a first
rotation speed and at least one rotation speed that is higher than
the first rotation speed, and the count obtained with the at least
one rotation speed that is higher than the first rotation
speed.
27. An information disc recording/playback apparatus as defined in
claim 19, wherein the track cross count is the number of track
crosses which is calculated on the basis of an average of counts
corresponding to more than one rotation, which counts are selected
from among the counts obtained by the repetition.
28. An information disc recording/playback apparatus as defined in
claim 27, wherein when calculating the track cross count, if the
value of the variable filter means which is reset by repetition at
the same rotation speed changes by a predetermined value or more,
the counts obtained before the change are not used as the counts
for calculating the average.
29. An information disc recording/playback apparatus capable of
recording or playing an information disc on which information
recording tracks are formed spirally or concentrically, said
apparatus comprising: a disc rotation means for rotating the
information disc at a predetermined speed; a reading means for
reading an information signal from the disc; a drive means for
driving the reading means in the direction of the radius of the
disc; a track cross detection means for generating track cross
signals on the basis of playback signals that are generated when
the reading means crosses the information tracks; a pulse width
storage means for holding the pulse width of a just-previous track
cross signal; a filter means for comparing the pulse width of the
just previous track cross signal with the pulse width of the
current track cross signal, and preventing the current track cross
signal from being outputted when the current track cross signal is
reduced by a predetermined value or more; a count means for
counting the pulses which are outputted from the variable filter
means; and a control means for determining a maximum rotation speed
that is lower than an allowable number of track crosses of the
information disc recording/playback apparatus on the basis of the
obtained counts for one or more rotation, or determining a maximum
rotation speed that is lower than an allowable track cross speed or
track cross acceleration of the information disc recording/playback
apparatus on the basis of the obtained counts for one or more
rotation, and the current disc rotation speed, and controlling the
disc rotation means so that the disc rotation means rotates the
information disc at a speed lower than the allowable maximum
rotation speed to record or reproduce data in/from the disc.
30. An information disc recording/playback apparatus as defined in
claim 29, wherein said information disc recording/playback
apparatus is able to record or play two or more kinds of
information discs having different track pitches; and setting of
the maximum rotation speed of the information disc
recording/playback apparatus is performed by detecting the track
pitch of the information disc, and determining a maximum rotation
speed that is lower than an allowable vibration amplitude of the
information disc recording/playback apparatus on the basis of the
count and the track pitch, or determining a maximum rotation speed
that is lower than an allowable vibration speed or vibration
acceleration of the information disc recording/playback apparatus
on the basis of the count, the track pitch, and the current disc
rotation speed.
31. A method for detecting vibrations of an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, said method comprising: a step of detecting the
track pitch of the information disc; a step of counting track cross
pulses on the basis of playback signals which are generated when
the information disc fixedly loaded on the apparatus is rotated and
a reading unit crosses the information tracks on the information
disc, thereby obtaining a count; a step of determining a maximum
rotation speed that is lower than an allowable vibration amplitude
of the information disc recording/playback apparatus, on the basis
of the obtained count and the track pitch; and a step of
determining a maximum rotation speed that is lower than an
allowable vibration speed or vibration acceleration of the
information disc recording/playback apparatus, on the basis of the
count, the track pitch, and the current disc rotation speed.
32. A method for detecting vibrations of an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, said method comprising: a step of detecting the
track pitch of the information disc; a step of detecting the track
cross direction indicating the direction in which a reading means
crosses the information tracks; a step of outputting rotation angle
information of the information disc, which is divided into n areas
for one rotation; a step of detecting two areas wherein the track
cross speed has the lowest value, from among the n-divided areas; a
step of counting track cross pulses, which are based on playback
signals that are generated when the information disc fixedly loaded
onto the apparatus is rotated and the reading means crosses the
information tracks on the information disc, such that the track
cross pulses with signs are counted while detecting the track cross
direction in an area where the track cross speed has the lowest
value, on the basis of the detected track cross direction and the
rotation angle information; a step of counting track cross pulses,
which are based on playback signals that are generated when the
information disc fixedly loaded onto the apparatus is rotated and
the reading means crosses the information tracks on the information
disc, such that the track cross pulses with signs are counted
without detecting the track cross direction, on the basis of the
track cross direction which has just previously been detected, in
an area where the track cross speed does not have the lowest value;
a step of determining a maximum rotation speed that is lower than
an allowable vibration amplitude of the information disc
recording/playback apparatus, on the basis of the obtained count
and the track pitch; and a step of determining a maximum rotation
speed that is lower than an allowable vibration speed or vibration
acceleration of the information disc recording/playback apparatus,
on the basis of the count, the track pitch, and the current disc
rotation speed.
33. A method for detecting vibrations of an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, said method comprising: a step of detecting the
track pitch of the information disc; a step of detecting the track
cross direction indicating the direction in which a reading means
crosses the information tracks; a step of outputting rotation angle
information of the information disc, which is divided into n areas
for one rotation; a step of detecting two areas wherein the track
cross speed has the lowest value, from among the n-divided areas; a
step of obtaining a first count on the basis of playback signals
which are generated when the information disc fixedly loaded onto
the apparatus is rotated and the reading means crosses the
information tracks on the information disc; a step of obtaining a
second count in which a sign is added to the count, on the basis of
the track cross direction which has just previously been detected,
when the information disc is rotated; a step of selecting the first
count in an area where the track cross speed has the lowest value,
and selecting the second count in an area where the track cross
speed does not have the lowest value, thereby counting the track
cross pulses for every rotation angle and outputting the count; a
step of determining a maximum rotation speed that is lower than an
allowable vibration amplitude of the information disc
recording/playback apparatus, on the basis of the obtained count
and the track pitch; and a step of determining a maximum rotation
speed that is lower than an allowable vibration speed or vibration
acceleration of the information disc recording/playback apparatus,
on the basis of the count, the track pitch, and the current disc
rotation speed.
34. A method for detecting vibrations of an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, said method comprising: a step of detecting the
track pitch of the information disc; a step of counting track cross
pulses on the basis of playback signals which are generated when
the information disc fixedly loaded onto the apparatus is rotated
at a first rotation speed and a reading unit crosses the
information tracks on the information disc, thereby obtaining a
count; a step of calculating a difference between a track cross
count which is obtained when the information disc is rotated with
at least one rotation speed that is higher than the first rotation
speed, and a count which is obtained when the information disc is
rotated at the first rotation speed, thereby obtaining a difference
count; a step of determining a maximum rotation speed that is lower
than an allowable vibration amplitude of the information disc
recording/playback apparatus, on the basis of the obtained
difference count and the track pitch; and a step of determining a
maximum rotation speed that is lower than an allowable vibration
speed or vibration acceleration of the information disc
recording/playback apparatus, on the basis of the difference count,
the track pitch, and the current disc rotation speed.
35. A method for detecting vibrations of an information disc
recording/playback apparatus capable of recording or playing an
information disc on which information recording tracks are formed
spirally or concentrically, said method comprising: a step of
counting track cross pulses on the basis of playback signals which
are generated when the information disc fixedly loaded on the
apparatus is rotated and a reading unit crosses the information
tracks on the information disc, thereby obtaining a count; a step
of comparing the widths of the detected track pulses with a
predetermined value, and invalidating the counts of track pulses
whose widths are shorter than the predetermined value; a step of
determining a maximum rotation speed that is lower than an
allowable number of track crosses of the information disc
recording/playback apparatus, on the basis of the count; and a step
of determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration, on the
basis of the count and the current disc rotation speed.
36. A method for detecting vibrations of an information disc
recording/playback apparatus capable of recording or playing an
information disc on which information recording tracks are formed
spirally or concentrically, said method comprising: a step of
counting track cross pulses on the basis of playback signals which
are generated when the information disc fixedly loaded on the
apparatus is rotated and a reading unit crosses the information
tracks on the information disc, thereby obtaining a count; a step
of detecting the track cross direction indicating the direction in
which the reading means crosses the information tracks; a step of
outputting rotation angle information of the information disc; a
step of comparing a set pulse width with the pulse width of the
current track cross pulse, and invalidating the count of the
current track cross pulse when its pulse width is decreased by a
predetermined value or more; a first count step of counting the
track cross pulses with signs, whose widths are not decreased by
the predetermined value or more, on the basis of the track cross
direction and the rotation angle information; a second count step
of counting the track cross pulses whose widths are not decreased
by the predetermined value or more, without detecting the track
cross direction, on the basis of the rotation angle information; a
step of setting the set pulse widths by repeating the steps of
obtaining the first and second counts by a required number of
times; a step of obtaining a count corresponding to one or more
rotation of the information disc, by obtaining the counts obtained
in the first and second count steps using the repeatedly set pulse
widths; a step of determining a maximum rotation speed that is
lower than an allowable number of track crosses of the information
disc recording/playback apparatus, on the basis of the count; and a
step of determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration, on the
basis of the count and the current disc rotation speed.
37. A method for detecting vibrations of an information disc
recording/playback apparatus capable of recording or playing an
information disc on which information recording tracks are formed
spirally or concentrically, said method comprising: a step of
counting track cross pulses on the basis of playback signals which
are generated when the information disc fixedly loaded on the
apparatus is rotated and a reading unit crosses the information
tracks on the information disc, thereby obtaining a count; a step
of storing the pulse width of a track cross pulse which has just
previously been detected; a step of comparing the stored track
cross pulse width with the pulse width of the current track cross
pulse, and invalidating the count of the current track cross pulse
when its pulse width is decreased by a predetermined value or more;
a step of determining a maximum rotation speed that is lower than
an allowable number of track crosses of the information disc
recording/playback apparatus, on the basis of the count; and a step
of determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration, on the
basis of the count and the current disc rotation speed.
Description
TECHNICAL FIELD
[0001] The present invention relates to an information disc
recording/playback apparatus having a vibration measurement means
for measuring vibrations caused by an eccentricity of a disc, and a
vibration detection method for the information disc
recording/playback apparatus. More particularly, the invention
relates to an information disc recording/playback apparatus having
a construction for performing vibration detection using track
counting.
BACKGROUND ART
[0002] In recent years, optical disc playback apparatuses have made
a remarkable increase in the recording/playback speed. The optical
disc playback apparatuses have achieved the increase in the
playback speed by increasing the rotation speed of optical
discs.
[0003] However, when the rotation speed of an optical disc is
increased, vibration due to an eccentricity of the optical disc
adversely affects control such as servo, resulting in a problem
that the user of the optical disc playback apparatus might feel
uncomfortable. In view of such problem, when an optical disc having
a large eccentricity is loaded on the optical disc playback
apparatus, the optical disc playback apparatus limits the rotation
speed of the disc to prevent the adverse effect of vibration due to
the disc of the large eccentricity. Therefore, measurement of
vibration amplitudes is an important technique for preventing the
adverse effect of vibration due to the disc of the large
eccentricity in the optical disc playback apparatus.
[0004] FIG. 8 is a block diagram illustrating a conventional
optical disc playback apparatus 800 having a structure for
detecting vibration with an acceleration sensor. In FIG. 8,
reference numeral 801 denotes a base, numeral 802 denotes a disc
motor mounted on the base 801, numeral 803 denotes an insulator
supporting the base 801, numeral 804 denotes a disc mounted on the
disc motor 802, numeral 805 denotes an acceleration sensor mounted
on the base 801, and numeral 806 denotes a measurement unit for
measuring the amount of eccentricity on the basis of the output of
the acceleration sensor 805.
[0005] Hereinafter, the operation will be described. When the disc
motor 802 on which the disc 804 is mounted is rotated at a
predetermined rpm, a centrifugal force in proportion to the amount
of eccentricity of the disc 804 is generated. The base 801
supported by the insulator 803 vibrates at an amplitude that is
determined by the amount of eccentricity of the disc 804, the total
mass of the base 801 and the constituents mounted on the base 801,
and the spring constant of the insulator 803.
[0006] The vibration of the base 801 is converted into an electric
signal by the acceleration sensor 805 mounted on the base 801. The
measurement unit 806 measures the vibration amplitude of the base
801 on the basis of the electric signal obtained by the
acceleration sensor 805.
[0007] Then, the measured vibration amplitude is compared with a
preset threshold value, thereby determining a maximum rotation
speed of the disc mounted on the optical disc device.
[0008] Furthermore, FIG. 9 is a block diagram illustrating a
conventional optical disc playback apparatus 900 performing
vibration detection using track counting, which is disclosed in
Japanese Published Patent Application No. 2000-113581. In FIG. 9,
the same reference numerals as those shown in FIG. 8 denote the
same or corresponding parts, and reference numeral 901 denotes an
optical head which is suspended over the base 801 via an elastic
member 902.
[0009] Reference numeral 903 denotes a light beam applied to the
disc 804 from the optical head 901, and numeral 904 denotes
information recording tracks which are concentrically or spirally
formed on an information recording surface 804A of the disc 804 at
a constant pitch. Furthermore, reference numeral 905 denotes a
track cross detection unit for generating track cross pulses and a
cross direction signal from signals which are reproduced when the
light beam 903 crosses the information recording tracks 904;
numeral 906 denotes a count unit for counting the track cross
pulses; numeral 907 denotes a measurement unit for determining the
amount of eccentricity from the counting result of the count unit
906; and numeral 908 denotes a motor control unit for controlling
the rpm of the disc motor 802, and outputting rotation angle
information to the measurement unit 907.
[0010] The distance between the optical head 901 and the disc 804
is kept constant so that the focus of the light beam 903 is
positioned on the information recording surface 804A of the disc
804. The position of the optical head 901 relative to the disc 804
in the direction of the radius of the disc 804 (the direction
indicated by an arrow R) has vibration characteristics represented
by a natural frequency of vibration foA which is determined by the
spring constant of the elastic member 902 comprising a material
such as metal, resin, or rubber, and the mass of the optical head
901.
[0011] The base 801 is supported by the insulator 803 comprising a
material such as metal, resin, or rubber. When the centrifugal
force generated by the rotation of the disc 804 is propagated
through the disc motor 802 to the base 801, the base 801 vibrates
on the basis of vibration characteristics represented by a natural
frequency of vibration foM which is determined by the total mass of
the constituents including the base 801, the optical head 901
mounted on the base 801, the disc motor 802, and the disc 804, and
the spring constant of the insulator 803.
[0012] The motor control unit 908 rotates the disc motor 802 at a
first rpm that is sufficiently lower than the natural frequency of
vibration foA. The optical disc 804 mounted on the disc motor 802
is rotated at the first rpm.
[0013] Within the range of the first rpm that is sufficiently lower
than the natural frequency of vibration foA, the optical head 901
vibrates together with the base 801. The relative position between
the optical head 901 and the optical disc 804 hardly changes.
Therefore, at the first rpm that is sufficiently lower than the
natural frequency of vibration foA, the light beam 903 crosses a
number of information recording tracks 904 equivalent to the amount
of eccentricity of the information recording tracks 904. The light
beam 903 generates track crosses as many as the information
recording tracks 904 the light beam 903 has crossed.
[0014] Then, the track cross detection unit 905 detects the track
crosses corresponding to the information recording tracks 904 the
light beam 903 has crossed, on the basis of the playback signals of
the optical head 901, and generates track cross pulses
corresponding to the detected track crosses. The track cross
detection unit 905 outputs the generated track cross pulses to the
count unit 906.
[0015] The count unit 906 counts the track cross pulses for one
rotation of the disc 804 on the basis of the rotation angle
information from the motor control unit 908. The measurement unit
907 stores a count result N1 of the track cross pulses for one
rotation of the disc 804, which are counted by the count unit
906.
[0016] Next, the motor control unit 908 rotates the disc motor 802
at a second rpm that is higher than the natural frequency of
vibration foA and lower than the natural frequency of vibration
foM. Then, a centrifugal force is generated in the disc 804 due to
the eccentricity of the disc 804. The base 801 vibrates at an
amplitude that is determined by the amount of eccentricity of the
disc 804, the total mass of the base 801 and the components mounted
on the base 801, and the spring constant of the insulator 803.
[0017] When the disc motor 802 rotates at the second rpm that is
higher than the natural frequency of vibration foA and lower than
the natural frequency of vibration foM, only the base 801, disc
motor 802, and disc 804 vibrate together while the optical head 901
is in the static state. Therefore, the relative displacement
between the disc 804 and the optical head 901 becomes equal to the
vibration displacement of the base 801. As a result, the light beam
903 generates track crosses as many as the tracks equivalent to an
amount in which the vibration amplitude of the base 801 is added to
the amount of eccentricity of the information recording tracks
904.
[0018] The track cross detection unit 905 detects the track crosses
as many as the tracks equivalent to the amount comprising the
amount of eccentricity of the information recording tracks 904 and
the vibration amplitude of the base 801, and generates track cross
pulses as may as the tracks equivalent to the amount comprising the
amount of eccentricity of the information recording tracks 904 and
the vibration amplitude of the base 801. The track cross detection
unit 905 outputs the generated track cross pulses to the count unit
906.
[0019] The count unit 906 counts the track cross pulses for one
rotation of the disc 804, on the basis of the rotation angle
information from the motor control unit 908. The measurement unit
907 subtracts the count result N1 from a count result N2 obtained
by the count unit 906, thereby obtaining the vibration amplitude of
the base 801 alone.
[0020] Then, the measured vibration amplitude is compared with a
threshold value which is prepared for each disc type, thereby
determining a maximum rotation speed of the disc loaded on the
optical disc device.
[0021] Furthermore, when detecting a vibration amplitude by a track
counting method, setting of a track count filter according to the
vibration speed becomes important for preventing false count.
Although a method of setting a track count filter for vibration
detection is not general at present, a method disclosed in Japanese
Published Patent Application No. Hei. 8-45089 is known as a method
of setting a track count filter at seeking. To be specific, an
optical disc device disclosed is provided with a PLL circuit for
outputting a control frequency according to the moving speed of an
optical head when the optical head is moved to a target track
position on the surface of an optical disc by a thread motor; an
F/V conversion circuit for converting the control frequency into a
voltage; and a ripple detection filter for attenuating a noise
component included in a ripple signal from an envelope detection
circuit, whose filter characteristic is changed according to the
voltage from the F/V conversion circuit. Thereby, the cut-off
frequency of the filter is varied according to the moving speed of
the optical head.
[0022] In the above-mentioned conventional method for detecting
vibration using the acceleration sensor 805, since the vibration
itself of the disc device is measured using the acceleration
sensor, a maximum rotation speed can be determined by comparing the
measurement result with a single threshold value that is
independent of the disc type. However, an increase in cost due to
mounting of the acceleration sensor 805 and a signal amplifier for
amplifying the signal from the acceleration sensor 805 is
considerable. Furthermore, it is necessary to secure a space for
mounting the acceleration sensor 805 and the signal amplifier.
[0023] Furthermore, in the conventional method for detecting
vibration using track counting, which is disclosed in Japanese
Published Patent Application No. 2000-113581, measurement of
vibration amplitudes can be carried out with reduced cost and
space, without using an acceleration sensor. However, since track
counting is employed, if the track pitch of the disc varies, the
value of the measured vibration amplitude also varies even under
the same vibration condition and, therefore, a threshold value must
be prepared for each of discs having different track pitches, and a
maximum rotation speed is determined by comparison with each
threshold value. However, the vibration of the disc device varies
depending on the setting condition of the disc device on a system,
and moreover, the vibration amplitude with which the user feels
uncomfortable depends on the human sense and so it varies depending
on the user. Therefore, a threshold value must be set for each
system on which the disc device is to be mounted. However, since
threshold setting varies depending on the loading condition or the
like of the disc to be used on the disc device, a large amount of
data must be measured, and the amount of data further increases
according to the number of disc types, whereby enormous time is
required.
[0024] Furthermore, in the method of setting a track count filter
disclosed in Japanese Published Patent Application No. Hei.
8-45089, when performing traverse seek, how the seek speed will
change is known in advance because acceleration or deceleration of
the seek speed is carried out according to a speed profile that has
previously been determined, and the response speed to the change in
the filter characteristics can be appropriately set according to
the predetermined profile. However, in the case where the frequency
and the speed change in the frequency are changed considerably due
to the eccentricity of the disc or the vibration amplitude like the
track count pulses for vibration detection, it is difficult to set
the response speed to the change in the filter characteristics,
resulting in false count when the response speed is too high or too
low.
[0025] The present invention is made to solve the above-described
problems and has for its object to provide an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus, which can
measure vibration amplitudes with reduced cost and space without
using an acceleration sensor, perform vibration detection using a
single threshold value that is independent of the disc type, and
perform accurate vibration detection even when direction detection
is difficult.
[0026] It is another object of the present invention to provide an
information disc recording/playback apparatus and a vibration
detection method for the information disc recording/playback
apparatus, which can provide a method of controlling the cut-off
frequency of a noise removal filter for track counting most suited
to vibration detection, and perform accurate vibration detection
with less false count.
[0027] Measures to Solve the Problems
[0028] According to claim 1 of the present invention, there is
provided an information disc recording/playback apparatus capable
of recording or playing at least two kinds of information discs
having different track pitches, on which information recording
tracks are formed spirally or concentrically, which apparatus
comprises: a disc rotation means for rotating the information disc
at a predetermined speed; a reading means for reading an
information signal from the disc; a drive means for driving the
reading means in the direction of the radius of the disc; a track
pitch detection means for detecting the track pitch of the
information disc from the information disc; a track cross detection
means for generating track cross signals on the basis of playback
signals that are generated when the reading means crosses the
information tracks; a count means for counting track cross pulses
that are detected by the track cross detection means, and
outputting the count; and a control means for determining a maximum
rotation speed that is lower than an allowable vibration amplitude
of the information disc recording/playback apparatus on the basis
of the count and the track pitch, or determining a maximum rotation
speed that is lower than an allowable vibration speed or vibration
acceleration speed of the information disc recording/playback
apparatus on the basis of the count, the track pitch, and the
current disc rotation speed, and controlling the disc rotation
means so that the disc rotation means rotates the information disc
at a speed lower than the allowable maximum rotation speed to
record or reproduce data in/from the disc.
[0029] According to claim 2 of the present invention, the
information disc recording/playback apparatus defined in claim 1
further comprises: a track cross direction detection means for
detecting a track cross direction indicating the direction in which
the reading means crosses the information tracks; a rotation angle
detection means for outputting rotation angle information of the
disc rotation means; and the count means for counting the track
cross pulses with signs, which are detected by the track cross
detection means, on the basis of the result of the detection by the
track cross direction detection means, and the rotation angle
information outputted from the rotation angle detection means.
[0030] According to claim 3 of the present invention, the
information disc recording/playback apparatus defined in claim 1
further comprises: a track cross direction detection means for
detecting a track cross direction indicating the direction in which
the reading means crosses the information tracks; a track cross
speed detection means for detecting the frequency of the track
cross pulses; a rotation angle detection means for outputting
rotation angle information of the disc rotation means; and the
count means for counting the track cross pulses with signs, which
are detected by the track cross detection means, on the basis of
the result of the detection by the track cross direction detection
means and the rotation angle information outputted from the
rotation angle detection means, while detecting the track cross
direction by the track cross direction detection means when the
result of the detection by the track cross speed detection means
indicates that the track cross speed is lower than a predetermined
value, and counting the track cross pulses with signs, without
detecting the track cross direction by the track cross direction
detection means, on the basis of the track cross direction that has
just previously been detected by the track cross direction
detection means, when the result of the detection by the track
cross speed detection means indicates that the track cross speed
becomes higher than the predetermined value.
[0031] According to claim 4 of the present invention, there is
provided an information disc recording/playback apparatus capable
of recording or playing at least two kinds of information discs
having different track pitches, on which information recording
tracks are formed spirally or concentrically, which apparatus
comprises: a disc rotation means for rotating the information disc
at a predetermined speed; a reading means for reading an
information signal from the disc; a drive means for driving the
reading means in the direction of the radius of the disc; a track
pitch detection means for detecting the track pitch of the
information disc from the information disc; a track cross detection
means for generating track cross signals on the basis of playback
signals that are generated when the reading means crosses the
information tracks; a track cross direction detection means for
detecting a track cross direction indicating the direction in which
the reading means crosses the information tracks; a rotation angle
detection means for outputting rotation angle information of the
disc rotation means, which is divided into n areas for one
rotation; a zero cross area detection means for detecting two areas
where the track cross speed has a lowest value, from among the n
areas; a count means for counting track cross pulses with signs,
which are detected by the track cross detection means, on the basis
of the result of the detection by the track cross direction
detection means and the rotation angle information outputted from
the rotation angle detection means, while detecting the track cross
direction by the track cross direction detection means, in an area
where the track cross speed has the lowest value according to the
result of the detection by the zero cross area detection means,
counting the track cross pulses with signs, without detecting the
track cross direction by the track cross direction detection means,
on the basis of the track cross direction that has just previously
been detected by the track cross direction detection means, in an
area where the track cross speed does not have the lowest value
according to the result of the detection by the zero cross area
detection means, and outputting the count; and a control means for
determining a maximum rotation speed that is lower than an
allowable vibration amplitude of the information disc
recording/playback apparatus on the basis of the count and the
track pitch, or determining a maximum rotation speed that is lower
than an allowable vibration speed or vibration acceleration speed
of the information disc recording/playback apparatus on the basis
of the count, the track pitch, and the current disc rotation speed,
and controlling the disc rotation means so that the disc rotation
means rotates the information disc at a speed lower than the
allowable maximum rotation speed to record or reproduce data
in/from the disc.
[0032] According to claim 5 of the present invention, there is
provided an information disc recording/playback apparatus capable
of recording or playing at least two kinds of information discs
having different track pitches, on which information recording
tracks are formed spirally or concentrically, which apparatus
comprises: a disc rotation means for rotating the information disc
at a predetermined speed; a reading means for reading an
information signal from the disc; a drive means for driving the
reading means in the direction of the radius of the disc; a track
pitch detection means for detecting the track pitch of the
information disc from the information disc; a track cross detection
means for generating track cross signals on the basis of playback
signals that are generated when the reading means crosses the
information tracks; a track cross direction detection means for
detecting a track cross direction indicating the direction in which
the reading means crosses the information tracks; a rotation angle
detection means for outputting rotation angle information of the
disc rotation means, which is divided into n areas for one
rotation; a zero cross area detection means for detecting two areas
where the track cross speed has a lowest value, from among the n
areas; a count means including a first count means for counting
track cross pulses with signs, which are detected by the track
cross detection means, on the basis of the result of the detection
by the track cross direction detection means and the rotation angle
information outputted from the rotation angle detection means, and
a second count means for counting the track cross pulses detected
by the track cross detection means, without detecting the track
cross direction, on the basis of the rotation angle information
outputted from the rotation angle detection means, which count
means obtains a first count of the first count means when the drive
means is disabled and the information disc loaded on the disc
rotation means is rotated, obtains a second count in which a sign
is added to the count of the second count means, on the basis of
the track cross direction which has just previously been detected
by the track cross direction detection means, when the drive means
is disabled and the information disc loaded on the disc rotation
means is rotated, selects the first count in an area where the
track cross speed has the lowest value according to the result of
the detection by the zero cross area detection means, selects the
second count in an area where the track cross speed does not have
the lowest value according to the result of the detection by the
zero cross area detection means, and counts the track cross pulses
for every rotation angle and outputting it; and a control means for
determining a maximum rotation speed that is lower than an
allowable vibration amplitude of the information disc
recording/playback apparatus on the basis of the counts and the
track pitch, or determining a maximum rotation speed that is lower
than an allowable vibration speed or vibration acceleration speed
of the information disc recording/playback apparatus on the basis
of the counts, the track pitch, and the current disc rotation
speed, and controlling the disc rotation means so that the disc
rotation means rotates the information disc at a speed lower than
the allowable maximum rotation speed to record or reproduce data
in/from the disc.
[0033] According to claim 6 of the present invention, in the
information disc recording/playback apparatus defined in claim 4 or
5, the rotation angle detection-means divides the rotation angle
information of the disc rotation means into six areas for each
rotation, and outputs the divided information; and the zero cross
area detection means detects, as zero cross areas, an area where
the count of the count means has the smallest value, and an area on
a diagonal line with respect to the area.
[0034] According to claim 7 of the present invention, there is
provided an information disc recording/playback apparatus capable
of recording or playing at least two kinds of information discs
having different track pitches, on which information recording
tracks are formed spirally or concentrically, which apparatus
comprises: a disc rotation means for rotating the information disc
at a predetermined speed; a reading means for reading an
information signal from the disc; a drive means for driving the
reading means in the direction of the radius of the disc; a track
pitch detection means for detecting the track pitch of the
information disc from the information disc; a track cross detection
means for generating track cross signals on the basis of playback
signals that are generated when the reading means crosses the
information tracks; a count means for counting track cross pulses
that are detected by the track cross detection means, and
outputting the count; and a control means for, using, as the count,
a difference between the track cross count that is obtained when
the information disc is rotated at a first rotation speed and at
least one rotation speed that is higher than the first rotation
speed, and a count that is measured with the at least one rotation
speed higher than the first rotation speed, determining a maximum
rotation speed that is lower than an allowable vibration amplitude
of the information disc recording/playback apparatus on the basis
of the count and the track pitch, or determining a maximum rotation
speed that is lower than an allowable vibration speed or vibration
acceleration speed of the information disc recording/playback
apparatus on the basis of the count, the track pitch, and the
current disc rotation speed, and controlling the disc rotation
means so that the disc rotation means rotates the information disc
at a speed lower than the allowable maximum rotation speed to
record or reproduce data in/from the disc.
[0035] According to claim 8 of the present invention, in the
information disc recording/playback apparatus defined in claim 7,
the first rotation speed is a sufficiently low speed at which no
vibration occurs between the information disc and the reading
means, and the track cross pulses due to the eccentricities of the
information disc and the disc rotation means are counted.
[0036] According to claim 9 of the present invention, in the
information disc recording/playback apparatus defined in claim 7,
the count means counts the track cross pulses at the first rotation
speed for a predetermined number of times, and counts the track
cross pulses with the at least one rotation speed that is higher
than the first rotation speed, for the predetermined number of
times; and the control means employs, as the count, an average of
counts for more than one time, which are selected from among the
counts obtained by the above-described repetition, or a value in
proportion to the average.
[0037] According to claim 10 of the present invention, in the
information disc recording/playback apparatus defined in claim 7,
the rotation angle detection means outputs the rotation angle
information of the disc rotation means, which is divided into six
areas for one rotation, and when a difference between the track
cross count measured at the first rotation speed with each of the
six-divided rotation angles, and the track cross count which is
measured with the at least one rotation speed higher than the first
rotation speed is as follows:
[0038] DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
[0039] (when n>5, n=n mod 6 (a remainder of n being divided by
6), the control means determines a maximum rotation speed that is
lower than the allowable amplitude of the information disc
recording/playback apparatus, on the basis of a value in proportion
to a vibration amount 1 or a vibration amount 2, or a value in
proportion to the second power of the vibration amount 1 or the
second power of the vibration amount 2, and the track pitch, the
vibration amounts 1 and 2 being represented as follows: 1 vibration
amount 1 [ n ] = 2 3 | DAT [ n ] 2 + DAT [ n ] DAT [ n + 1 ] + DAT
[ n + 1 ] 2 | ( Formula 12 ) vibration amount 2 [ n ] = 2 3 | DAT [
n ] 2 - DAT [ n ] DAT [ n + 2 ] + DAT [ n + 2 ] 2 | ( Formula 13
)
[0040] According to claim 11 of the present invention, in the
information disc recording/playback apparatus defined in claim 10,
the control means determines a maximum rotation speed that is lower
than the allowable amplitude of the information disc
recording/playback apparatus, on the basis of a value in proportion
to an average of twelve vibration amounts 1 or vibration amounts 2
which are calculated for n=0.about.5 according to (Formula 12) or
(Formula 13), and the track pitch, or a value in proportion to an
average of m pieces of central values selected from among the
twelve vibration amounts 1 or vibration amounts 2, and the track
pitch, or a value in proportion to an average of m pieces of
central values selected from the second powers of the twelve
vibration amounts 1 or vibration amounts 2, and the track
pitch.
[0041] According to claim 12 of the present invention, in the
information disc recording/playback apparatus defined in claim 7,
the rotation angle detection means divides the rotation angle
information of the disc rotation means into six areas for one
rotation, and outputs the divided rotation angle information; and
when a difference between the track cross count which is obtained
at the first rotation speed for each of the six-divided rotation
angles, and the track cross count which is obtained with the at
least one rotation speed higher than the first rotation speed is
represented by
[0042] DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
[0043] (when n>5, n=n mod 6 (a remainder of n being divided by
6), and the rotation speed of the disc rotation means is Vrpm[rpm],
the control means determines a maximum rotation speed that is lower
than the allowable amplitude of the information disc
recording/playback apparatus, on the basis of a value in proportion
to a vibration speed 1 or a vibration speed 2, or a value in
proportion to the second power of the vibration speed 1 or the
second power of the vibration speed 2, and the track pitch, the
vibration speeds 1 and 2 being represented by 2 vibration speed 1 [
n ] = 2 V rpm 60 2 3 | DAT [ n ] 2 + DAT [ n ] DAT [ n + 1 ] + DAT
[ n + 1 ] 2 | ( Formula 14 ) vibration speed 2 [ n ] = 2 V rpm 60 2
3 | DAT [ n ] 2 - DAT [ n ] DAT [ n + 2 ] + DAT [ n + 2 ] 2 | (
Formula 15 )
[0044] According to claim 13 of the present invention, in the
information disc recording/playback apparatus defined in claim 12,
the control means determines a maximum rotation speed that is lower
than the allowable amplitude of the information disc
recording/playback apparatus, on the basis of a value in proportion
to an average of twelve vibration speeds 1 or vibration speeds 2
which are calculated for n=0.about.5 according to (Formula 14) and
(Formula 15), respectively, and the track pitch, or a value in
proportion to an average of m pieces of central values selected
from the values of the twelve vibration speeds 1 or vibration
speeds 2, and the track pitch, or a value in proportion to an
average of m pieces of central values selected from the second
powers of the twelve vibration speeds 1 or the second powers of the
vibration speeds 2, and the track pitch.
[0045] According to claim 14 of the present invention, in the
information disc recording/playback apparatus defined in claim 7,
the rotation angle detection means divides the rotation angle
information of the disc rotation means into six areas for one
rotation, and outputs the divided rotation angle information; and
when a difference between the track cross amount which is measured
at the first rotation speed for each of the six-divided rotation
angles, and the track cross amount which is measured with the at
least one rotation speed higher than the first rotation speed is
represented by
[0046] DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
[0047] (when n>5, n=n mod 6 (a remainder of n being divided by
6), and the rotation speed of the disc rotation means is Vrpm[rpm],
the control means determines a maximum rotation speed that is lower
than the allowable amplitude of the information disc
recording/playback apparatus, on the basis of a value in proportion
to a vibration acceleration 1 or a vibration acceleration 2, or a
value in proportion to the second power of the vibration
acceleration 1 or the second power of the vibration acceleration 2,
and the track pitch, the vibration accelerations 1 and 2 being
represented by 3 vibration acceleration 1 [ n ] = ( 2 V rpm 60 ) 2
2 3 | DAT [ n ] 2 + DAT [ n ] DAT [ n + 1 ] + DAT [ n + 1 ] 2 | (
Formula 16 ) vibration acceleration 2 [ n ] = ( 2 V rpm 60 ) 2 2 3
| DAT [ n ] 2 - DAT [ n ] DAT [ n + 2 ] + DAT [ n + 2 ] 2 | (
Formula 17 )
[0048] According to claim 15 of the present invention, in the
information disc recording/playback apparatus defined in claim 14,
the control means determines a maximum rotation speed that is lower
than the allowable amplitude of the information disc
recording/playback apparatus, on the basis of a value in proportion
to an average of twelve vibration accelerations 1 or vibration
accelerations 2 which are calculated for n=0.about.5 according to
(Formula 16) and (Formula 17), respectively, and the track pitch,
or a value in proportion to an average of m pieces of central
values selected from the values of the twelve vibration
accelerations 1 or vibration accelerations 2, and the track pitch,
or a value in proportion to an average of m pieces of central
values selected from the second powers of the twelve vibration
accelerations 1 or the second powers of the twelve vibration
accelerations 2, and the track pitch.
[0049] According to claim 16 of the present invention, in the
information disc recording/playback apparatus defined in claim 1,
the track pitch detection means detects the type of the loaded
information disc, and selects a track pitch corresponding to the
detected disc type, with reference to a table in which standard
track pitches corresponding to the respective types of the
information discs are described.
[0050] According to claim 17 of the present invention, the
information disc recording/playback apparatus as defined in claim 1
further comprises: a move distance detection means for detecting
the distance by which the reading means moves; and the track pitch
detection means for making the reading means move for a
predetermined period of time or by a predetermined distance when
the information disc is loaded, counting the number of tracks the
reading means crosses while it is moving, and detecting the track
pitch on the basis of the move distance and the track cross
count.
[0051] According to claim 18 of the present invention, the
information recording/playback apparatus defined in claim 1 further
comprises: a linear speed detection means for detecting the linear
speed of the information disc; a a playback speed detection means
for detecting the current playback speed of the information disc;
and the track pitch detection means for calculating the track pitch
of the information disc, on the basis of the detected type of the
information disc, the linear speed of the information disc detected
by the linear speed detection means, the playback speed detected at
a predetermined rotation speed and a predetermined address, the
predetermined rotation speed, the predetermined address, the
innermost radius of data area which is unique to the detected type
of the disc, and the data rate when the disc is played at the
predetermined playback speed which is unique to the type of the
disc.
[0052] According to claim 19 of the present invention, there is
provided an information disc recording/playback apparatus capable
of recording or playing an information disc on which information
recording tracks are formed spirally or concentrically, which
apparatus comprises: a disc rotation means for rotating the
information disc at a predetermined speed; a reading means for
reading an information signal from the disc; a drive means for
driving the reading means in the direction of the radius of the
disc; a track cross detection means for generating track cross
pulses on the basis of playback signals that are generated when the
reading means crosses the information tracks; a variable filter
means for preventing counting of pulses whose widths are narrower
than a set value, among the track cross pulses; a count means for
counting the pulses outputted from the variable filter means; and a
control means for determining a maximum rotation speed that is
lower than an allowable number of track crosses of the information
disc recording/playback apparatus on the basis of the count, or
determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration of the
information disc recording/playback apparatus on the basis of the
count and the current disc rotation speed, and controlling the disc
rotation means so that the disc rotation means rotates the
information disc at a speed lower than the allowable maximum
rotation speed to record or reproduce data in/from the disc.
[0053] According to claim 20 of the present invention, the
information disc recording/playback apparatus defined in claim 19,
further comprises: a track cross direction detection means for
detecting the track cross direction which indicates the direction
in which the reading means crosses the information tracks; a
rotation angle detection means for outputting rotation angle
information of the disc rotation means; and the count means for
counting the track cross pulses with signs, which are detected by
the track cross detection means, on the basis of the result of the
detection by the track cross direction detection means and the
rotation angle information outputted from the rotation angle
detection means.
[0054] According to claim 21 of the present invention, there is
provided an information disc recording/playback apparatus capable
of recording or playing an information disc on which information
recording tracks are formed spirally or concentrically, which
apparatus comprises: a disc rotation means for rotating the
information disc at a predetermined speed; a reading means for
reading an information signal from the disc; a drive means for
driving the reading means in the direction of the radius of the
disc; a track cross detection means for generating track cross
pulses on the basis of playback signals that are generated when the
reading means crosses the information tracks; a variable filter
means for preventing counting of pulses whose widths are narrower
than a set value, among the track cross pulses; a track cross
direction detection means for detecting the track cross direction
which indicates the direction in which the reading means crosses
the information tracks; a rotation angle detection means for
outputting rotation angle information of the disc rotation means; a
count means including a first count means for counting the track
cross pulses with signs, which are outputted from the filter means,
on the basis of the result of the detection by the track cross
direction detection means and the rotation angle information
outputted from the rotation angle detection means, and a second
count means for counting the track cross pulses outputted from the
filter means, without detecting the track cross direction, on the
basis of the rotation angle information outputted from the rotation
angle detection means, which count means obtains the count of the
first or second count means when an initial value of count is set
for setting an initial value of the variable filter means, a value
of the variable filter is set on the basis of the count and the
current rotation speed, the drive means is disabled, and the
information disc loaded on the disc rotation means is rotated at a
predetermined rotation speed, and repeats the process of obtaining
the count of the first or second count means when the value of the
variable filter is set and the information disc is rotated at the
predetermined speed, for a required number of times, thereby
obtaining the counts for more than one rotation; and a control
means for determining a maximum rotation speed that is lower than
an allowable number of track crosses of the information disc
recording/playback apparatus on the basis of the count, or
determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration of the
information disc recording/playback apparatus on the basis of the
count and the current disc rotation speed, and controlling the disc
rotation means so that the disc rotation means rotates the
information disc at a speed lower than the allowable maximum
rotation speed to record or reproduce data in/from the disc.
[0055] According to claim 22 of the present invention, in the
information disc recording/playback apparatus defined in claim 21,
the count means obtains the count of the first count means when the
value of the variable filter is set on the basis of the count and
the current rotation speed, the drive means is disabled, and the
information disc loaded on the disc rotation means is rotated at a
predetermined rotation speed, and repeats the process of obtaining
the count of the first count means when the information disc is
rotated at the predetermined speed, for a required number of times,
thereby obtaining the counts for more than one rotation.
[0056] According to claim 23 of the present invention, in the
information disc recording/playback apparatus defined in claim 21
or 22, when setting the value of the variable filter on the basis
of the count and the current rotation speed, if the count is one
obtained without detecting the track cross direction,
[0057] assuming that the total number of track crosses per rotation
is 4Tc, and the current rotation speed is Vrpm,
[0058] a maximum track cross speed is calculated by 4 maximum track
cross speed = 2 V rpm 60 T c ( Formula 18 )
[0059] and, on the basis of the calculated maximum track cross
speed, the value of the variable filter is set, and a minimum track
count pulse width is set.
[0060] According to claim 24 of the present invention, in the
information disc recording/playback apparatus defined in claim 21
or 22, the rotation angle detection means divides the rotation
angle information of the disc rotation means into six areas for one
rotation and outputs the divided rotation angle information,
and
[0061] when the count is one obtained when the track cross
direction is detected, the count at each of the six-divided
rotation angles is represented by
[0062] DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
[0063] (when n>5, n=n mod 6 (a remainder of n being divided by
6), and
[0064] the rotation speed of the disc rotation means is
Vrpm[rpm],
[0065] a value in proportion to a maximum track cross speed 1 or a
maximum track cross speed 2 which are represented as follows are
calculated as a maximum track cross speed, 5 maximum track cross
speed 1 [ n ] = 2 V rpm 60 2 3 | DAT [ n ] 2 + DAT [ n ] DAT [ n +
1 ] + DAT [ n + 1 ] 2 | ( Formula 19 ) maximum track cross speed 2
[ n ] = 2 V rpm 60 2 3 | DAT [ n ] 2 - DAT [ n ] DAT [ n + 2 ] +
DAT [ n + 2 ] 2 | ( Formula 20 )
[0066] and a value in proportion to an average of twelve maximum
track cross speeds 1 or maximum track cross speeds 2 which are
calculated for n=0.about.5 according to (Formula 19) and (Formula
20), respectively, or a value in proportion to an average of m
pieces of central values selected from the values of the twelve
maximum track cross speeds 1 or maximum track cross speeds 2, is
employed as a maximum track cross speed.
[0067] According to claim 25 of the present invention, in the
information disc recording/playback apparatus defined in claim 24,
when the value of the variable filter is set on the basis of the
count and the current rotation speed, if the count is one obtained
when the track cross direction is detected, the count at each of
the six-divided rotation angles is represented by
[0068] DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
[0069] (when n>5, n=n mod 6 (a remainder of n being divided by
6), and
[0070] the rotation speed of the disc rotation means is
Vrpm[rpm],
[0071] a maximum track cross speed is calculated on the basis of
the following formulae,
4T.sub.C=.vertline.DAT[0].vertline.+.vertline.DAT[1].vertline.+.vertline.D-
AT[2].vertline.+.vertline.DAT[3].vertline.+.vertline.DAT[4].vertline.+.ver-
tline.DAT[5].vertline. (Formula 21)
[0072] 6 maximum track cross speed = 2 V rpm 60 T c 1 cos 6 = 2 V
rpm 60 T c 2 3 ( Formula 22 )
[0073] and, on the basis of the maximum track cross speed so
calculated, the value of the variable filter is set, and a minimum
track count pulse width is set.
[0074] According to claim 26 of the present invention, in the
information disc recording/playback apparatus defined in claim 19,
when setting the maximum rotation speed of the information disc
recording/playback apparatus, the control means employs, as the
count, a difference between the track cross count that is obtained
when the information disc is rotated at a first rotation speed and
at least one rotation speed that is higher than the first rotation
speed, and the count obtained with the at least one rotation speed
that is higher than the first rotation speed.
[0075] According to claim 27 of the present invention, in the
information disc recording/playback apparatus defined in claim 19,
the track cross count is the number of track crosses which is
calculated on the basis of an average of counts corresponding to
more than one rotation, which counts are selected from among the
counts obtained by the repetition.
[0076] According to claim 28 of the present invention, in the
information disc recording/playback apparatus defined in claim 27,
when calculating the track cross count, if the value of the
variable filter means which is reset by repetition at the same
rotation speed changes by a predetermined value or more, the counts
obtained before the change are not used as the counts for
calculating the average.
[0077] According to claim 29 of the present invention, there is
provided an information disc recording/playback apparatus capable
of recording or playing an information disc on which information
recording tracks are formed spirally or concentrically, which
apparatus comprises: a disc rotation means for rotating the
information disc at a predetermined speed; a reading means for
reading an information signal from the disc; a drive means for
driving the reading means in the direction of the radius of the
disc; a track cross detection means for generating track cross
signals on the basis of playback signals that are generated when
the reading means crosses the information tracks; a pulse width
storage means for holding the pulse width of a just-previous track
cross signal; a filter means for comparing the pulse width of the
just-previous track cross signal with the pulse width of the
current track cross signal, and preventing the current track cross
signal from being outputted when the current track cross signal is
reduced by a predetermined value or more; a count means for
counting the pulses which are outputted from the variable filter
means; and a control means for determining a maximum rotation speed
that is lower than an allowable number of track crosses of the
information disc recording/playback apparatus on the basis of the
obtained counts for one or more rotation, or determining a maximum
rotation speed that is lower than an allowable track cross speed or
track cross acceleration of the information disc recording/playback
apparatus on the basis of the obtained counts for one or more
rotation, and the current disc rotation speed, and controlling the
disc rotation means so that the disc rotation means rotates the
information disc at a speed lower than the allowable maximum
rotation speed to record or reproduce data in/from the disc.
[0078] According to claim 30 of the present invention, in the
information disc recording/playback apparatus defined in claim 29,
the information disc recording/playback apparatus is able to record
or play two or more kinds of information discs having different
track pitches; and setting of the maximum rotation speed of the
information disc recording/playback apparatus is performed by
detecting the track pitch of the information disc, and determining
a maximum rotation speed that is lower than an allowable vibration
amplitude of the information disc recording/playback apparatus on
the basis of the count and the track pitch, or determining a
maximum rotation speed that is lower than an allowable vibration
speed or vibration acceleration of the information disc
recording/playback apparatus on the basis of the count, the track
pitch, and the current disc rotation speed.
[0079] According to claim 31 of the present invention, there is
provided a vibration detection method for an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, which method comprises: a step of detecting the
track pitch of the information disc; a step of counting track cross
pulses on the basis of playback signals which are generated when
the information disc fixedly loaded on the apparatus is rotated and
a reading unit crosses the information tracks on the information
disc, thereby obtaining a count; a step of determining a maximum
rotation speed that is lower than an allowable vibration amplitude
of the information disc recording/playback apparatus, on the basis
of the obtained count and the track pitch; and a step of
determining a maximum rotation speed that is lower than an
allowable vibration speed or vibration acceleration of the
information disc recording/playback apparatus, on the basis of the
count, the track pitch, and the current disc rotation speed.
[0080] According to claim 32 of the present invention, there is
provided a vibration detection method for an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, which method comprises: a step of detecting the
track pitch of the information disc; a step of detecting the track
cross direction indicating the direction in which a reading means
crosses the information tracks; a step of outputting rotation angle
information of the information disc, which is divided into n areas
for one rotation; a step of detecting two areas wherein the track
cross speed has the lowest value, from among the n-divided areas; a
step of counting track cross pulses, which are based on playback
signals that are generated when the information disc fixedly loaded
onto the apparatus is rotated and the reading means crosses the
information tracks on the information disc, such that the track
cross pulses with signs are counted while detecting the track cross
direction in an area where the track cross speed has the lowest
value, on the basis of the detected track cross direction and the
rotation angle information; a step of counting track cross pulses,
which are based on playback signals that are generated when the
information disc fixedly loaded onto the apparatus is rotated and
the reading means crosses the information tracks on the information
disc, such that the track cross pulses with signs are counted
without detecting the track cross direction, on the basis of the
track cross direction which has just previously been detected, in
an area where the track cross speed does not have the lowest value;
a step of determining a maximum rotation speed that is lower than
an allowable vibration amplitude of the information disc
recording/playback apparatus, on the basis of the obtained count
and the track pitch; and a step of determining a maximum rotation
speed that is lower than an allowable vibration speed or vibration
acceleration of the information disc recording/playback apparatus,
on the basis of the count, the track pitch, and the current disc
rotation speed.
[0081] According to claim 33 of the present invention, there is
provided a vibration detection method for an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, which method comprises: a step of detecting the
track pitch of the information disc; a step of detecting the track
cross direction indicating the direction in which a reading means
crosses the information tracks; a step of outputting rotation angle
information of the information disc, which is divided into n areas
for one rotation; a step of detecting two areas wherein the track
cross speed has the lowest value, from among the n-divided areas; a
step of obtaining a first count on the basis of playback signals
which are generated when the information disc fixedly loaded onto
the apparatus is rotated and the reading means crosses the
information tracks on the information disc; a step of obtaining a
second count in which a sign is added to the count, on the basis of
the track cross direction which has just previously been detected,
when the information disc is rotated; a step of selecting the first
count in an area where the track cross speed has the lowest value,
and selecting the second count in an area where the track cross
speed does not have the lowest value, thereby counting the track
cross pulses for every rotation angle and outputting the count; a
step of determining a maximum rotation speed that is lower than an
allowable vibration amplitude of the information disc
recording/playback apparatus, on the basis of the obtained count
and the track pitch; and a step of determining a maximum rotation
speed that is lower than an allowable vibration speed or vibration
acceleration of the information disc recording/playback apparatus,
on the basis of the count, the track pitch, and the current disc
rotation speed.
[0082] According to claim 34 of the present invention, there is
provided a vibration detection method for an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, which method comprises: a step of detecting the
track pitch of the information disc; a step of counting track cross
pulses on the basis of playback signals which are generated when
the information disc fixedly loaded onto the apparatus is rotated
at a first rotation speed and a reading unit crosses the
information tracks on the information disc, thereby obtaining a
count; a step of calculating a difference between a track cross
count which is obtained when the information disc is rotated with
at least one rotation speed that is higher than the first rotation
speed, and a count which is obtained when the information disc is
rotated at the first rotation speed, thereby obtaining a difference
count; a step of determining a maximum rotation speed that is lower
than an allowable vibration amplitude of the information disc
recording/playback apparatus, on the basis of the obtained
difference count and the track pitch; and a step of determining a
maximum rotation speed that is lower than an allowable vibration
speed or vibration acceleration of the information disc
recording/playback apparatus, on the basis of the difference count,
the track pitch, and the current disc rotation speed.
[0083] According to claim 35 of the present invention, there is
provided a vibration detection method for an information disc
recording/playback apparatus capable of recording or playing an
information disc on which information recording tracks are formed
spirally or concentrically, which method comprises: a step of
counting track cross pulses on the basis of playback signals which
are generated when the information disc fixedly loaded on the
apparatus is rotated and a reading unit crosses the information
tracks on the information disc, thereby obtaining a count; a step
of comparing the widths of the detected track pulses with a
predetermined value, and invalidating the counts of track pulses
whose widths are shorter than the predetermined value; a step of
determining a maximum rotation speed that is lower than an
allowable number of track crosses of the information disc
recording/playback apparatus, on the basis of the count; and a step
of determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration, on the
basis of the count and the current disc rotation speed.
[0084] According to claim 36 of the present invention, there is
provided a vibration detection method for an information disc
recording/playback apparatus capable of recording or playing an
information disc on which information recording tracks are formed
spirally or concentrically, which method comprises: a step of
counting track cross pulses on the basis of playback signals which
are generated when the information disc fixedly loaded on the
apparatus is rotated and a reading unit crosses the information
tracks on the information disc, thereby obtaining a count; a step
of detecting the track cross direction indicating the direction in
which the reading means crosses the information tracks; a step of
outputting rotation angle information of the information disc; a
step of comparing a set pulse width with the pulse width of the
current track cross pulse, and invalidating the count of the
current track cross pulse when its pulse width is decreased by a
predetermined value or more; a first count step of counting the
track cross pulses with signs, whose widths are not decreased by
the predetermined value or more, on the basis of the track cross
direction and the rotation angle information; a second count step
of counting the track cross pulses whose widths are not decreased
by the predetermined value or more, without detecting the track
cross direction, on the basis of the rotation angle information; a
step of setting the set pulse widths by repeating the steps of
obtaining the first and second counts by a required number of
times; a step of obtaining a count corresponding to one or more
rotation of the information disc, by obtaining the counts obtained
in the first and second count steps using the repeatedly set pulse
widths; a step of determining a maximum rotation speed that is
lower than an allowable number of track crosses of the information
disc recording/playback apparatus, on the basis of the count; and a
step of determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration, on the
basis of the count and the current disc rotation speed.
[0085] According to claim 37 of the present invention, there is
provided a vibration detection method for an information disc
recording/playback apparatus capable of recording or playing an
information disc on which information recording tracks are formed
spirally or concentrically, which method comprises: a step of
counting track cross pulses on the basis of playback signals which
are generated when the information disc fixedly loaded on the
apparatus is rotated and a reading unit crosses the information
tracks on the information disc, thereby obtaining a count; a step
of storing the pulse width of a track cross pulse which has just
previously been detected; a step of comparing the stored track
cross pulse width with the pulse width of the current track cross
pulse, and invalidating the count of the current track cross pulse
when its pulse width is decreased by a predetermined value or more;
a step of determining a maximum rotation speed that is lower than
an allowable number of track crosses of the information disc
recording/playback apparatus, on the basis of the count; and a step
of determining a maximum rotation speed that is lower than an
allowable track cross speed or track cross acceleration, on the
basis of the count and the current disc rotation speed.
[0086] As described above, according to an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus relating to the
present invention, there is provided an information disc
recording/playback apparatus capable of recording or playing at
least two kinds of information discs having different track
pitches, on which information recording tracks are formed spirally
or concentrically, which apparatus comprises: a disc rotation means
for rotating the information disc at a predetermined speed; a
reading means for reading an information signal from the disc; a
drive means for driving the reading means in the direction of the
radius of the disc; a track pitch detection means for detecting the
track pitch of the information disc from the information disc; a
track cross detection means for generating track cross signals on
the basis of playback signals that are generated when the reading
means crosses the information tracks; a count means for counting
track cross pulses that are detected by the track cross detection
means, and outputting the count; and a control means for
determining a maximum rotation speed that is lower than an
allowable vibration amplitude of the information disc
recording/playback apparatus on the basis of the count and the
track pitch, or determining a maximum rotation speed that is lower
than an allowable vibration speed or vibration acceleration speed
of the information disc recording/playback apparatus on the basis
of the count, the track pitch, and the current disc rotation speed,
and controlling the disc rotation means so that the disc rotation
means rotates the information disc at a speed lower than the
allowable maximum rotation speed to record or reproduce data
in/from the disc. Therefore, the vibration amplitude, or vibration
speed, or vibration acceleration is evaluated considering the track
pitch of the disc, and the maximum rotation speed lower than the
allowable vibration amplitude, or vibration speed, or vibration
acceleration of the information disc recording/playback apparatus
is determined, whereby vibration detection can be carried out using
a single threshold value, regardless of the type of the information
disc.
[0087] Furthermore, according to an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus relating to the
present invention, there is provided an information disc
recording/playback apparatus capable of recording or playing an
information disc on which information recording tracks are formed
spirally or concentrically, which apparatus comprises: a disc
rotation means for rotating the information disc at a predetermined
speed; a reading means for reading an information signal from the
disc; a drive means for driving the reading means in the direction
of the radius of the disc; a track cross detection means for
generating track cross pulses on the basis of playback signals that
are generated when the reading means crosses the information
tracks; a variable filter means for preventing counting of pulses
whose widths are narrower than a set value, among the track cross
pulses; a count means for counting the pulses outputted from the
variable filter means; and a control means for determining a
maximum rotation speed that is lower than an allowable number of
track crosses of the information disc recording/playback apparatus
on the basis of the count, or determining a maximum rotation speed
that is lower than an allowable track cross speed or track cross
acceleration of the information disc recording/playback apparatus
on the basis of the count and the current disc rotation speed, and
controlling the disc rotation means so that the disc rotation means
rotates the information disc at a speed lower than the allowable
maximum rotation speed to record or reproduce data in/from the
disc. Since setting of the track cross filter is carried out on the
basis of the track cross count and the current rotation speed, even
when the track cross speed varies significantly due to the
eccentricity or vibration of the disc, track counting most suitable
for vibration detection can be accurately carried out at all
times.
[0088] Furthermore, according to an information disc
recording/playback apparatus relating to the present invention,
there is provided an information disc recording/playback apparatus
capable of recording or playing an information disc on which
information recording tracks are formed spirally or concentrically,
which apparatus comprises: a disc rotation means for rotating the
information disc at a predetermined speed; a reading means for
reading an information signal from the disc; a drive means for
driving the reading means in the direction of the radius of the
disc; a track cross detection means for generating track cross
signals on the basis of playback signals that are generated when
the reading means crosses the information tracks; a pulse width
storage means for holding the pulse width of a just-previous track
cross signal; a filter means for comparing the pulse width of the
just-previous track cross signal with the pulse width of the
current track cross signal, and preventing the current track cross
signal from being outputted when the current track cross signal is
reduced by a predetermined value or more; a count means for
counting the pulses which are outputted from the variable filter
means; and a control means for determining a maximum rotation speed
that is lower than an allowable number of track crosses of the
information disc recording/playback apparatus on the basis of the
obtained counts for one or more rotation, or determining a maximum
rotation speed that is lower than an allowable track cross speed or
track cross acceleration of the information disc recording/playback
apparatus on the basis of the obtained counts for one or more
rotation, and the current disc rotation speed, and controlling the
disc rotation means so that the disc rotation means rotates the
information disc at a speed lower than the allowable maximum
rotation speed to record or reproduce data in/from the disc.
Therefore, when the current pulse width is smaller than the
previous pulse width by a predetermined value, this pulse is judged
as one caused by false detection due to noise and is not counted,
whereby track counting most suitable for vibration detection can be
accurately carried out at all times, without requiring time for
excess measurement.
BRIEF DESCRIPTION OF THE DRAWINGS
[0089] FIG. 1 is a block diagram illustrating the construction of a
DVD-ROM player in the case where an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus according to a
first or fourth embodiment of the invention are applied to the
DVD-ROM player.
[0090] FIG. 2 is a block diagram illustrating the construction of a
DVD-ROM player in the case where an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus according to a
second embodiment of the invention are applied to the DVD-ROM
player.
[0091] FIG. 3 is a block diagram illustrating the construction of a
DVD-ROM player in the case where an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus according to a
third embodiment of the invention are applied to the DVD-ROM
player.
[0092] FIG. 4 is a block diagram illustrating the construction of a
DVD-ROM player in the case where an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus according to a
fifth embodiment of the invention are applied to the DVD-ROM
player.
[0093] FIG. 5 is a block diagram illustrating the construction of a
DVD-ROM player in the case where an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus according to a
sixth, seventh, or eighth embodiment of the invention are applied
to the DVD-ROM player.
[0094] FIG. 6 is a diagram illustrating a graph showing the amount
of displacement of the count at every rotation angle, which
displacement is caused by vibration or eccentricity, when the
present invention is applied to the DVD-ROM player.
[0095] FIG. 7 is a block diagram illustrating the construction of a
DVD-ROM player in the case where an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus according to a
ninth embodiment of the invention are applied to the DVD-ROM
player.
[0096] FIG. 8 is a block diagram illustrating the construction of a
conventional optical disc playback apparatus which performs
vibration detection using an acceleration sensor.
[0097] FIG. 9 is a block diagram illustrating the construction of a
conventional optical disc playback apparatus which performs
vibration detection using track counting.
[0098] FIG. 10 is a block diagram illustrating the construction of
another DVD-ROM player in the case where an information disc
recording/playback apparatus and a vibration detection method for
the information disc recording/playback apparatus according to the
fifth embodiment of the invention are applied to the DVD-ROM
player.
BEST MODE TO EXECUTE THE INVENTION
[0099] (Embodiment 1)
[0100] An information disc recording/playback apparatus and a
vibration detection method for the information disc
recording/playback apparatus according to a first embodiment of the
present invention will be described taking a DVD-ROM player as an
example, with reference to FIG. 1.
[0101] In FIG. 1, a DVD-ROM player 101 is able to play various
kinds of optical discs 102. The DVD-ROM player 101 according to
this first embodiment is able to play the following discs: CD-ROM
(CD-ROM, CD-R, CD-RW), DVD-ROM (DVD-5, DVD-9, DVD-R4.7G), and
DVD-R3.9G, and the standard track pitches of these discs are as
follows:
1 CD-ROM 1.6 .mu.m DVD-ROM 0.74 .mu.m DVD-R3.9G 0.80 .mu.m
[0102] Reference numeral 103 denotes a disc rotation means for
rotating the optical disc 102 mounted on the DVD-ROM player 101 at
a predetermined rpm. Reference numeral 104 denotes a reading means
for reading an information signal from the optical disc 102. In the
DVD-ROM player 101, the reading means 104 comprises, for example, a
laser emission element 105 for emitting two laser beams having
different oscillation wavelengths, one for a CD-ROM and the other
for a DVD-ROM; an objective lens 106 for converging the laser
beams; and a two-element photodetector 107, one for a CD-ROM and
the other for a DVD-ROM. The reading means 104 amplifies the
outputs from the photodetector 107, selects one of the output
signals from the photodetector 107 according to the type of the
optical disc 102, generates a tracking error (TE) signal, a focus
error (FE) signal, a playback signal (RF), an All Sum signal (AS),
an RF envelope signal (RFENV) and the like, and outputs these
signals.
[0103] Reference numeral 108 denotes a conversion means for
converting the playback signal outputted from the reading means 104
into digital data. Reference numeral 109 denotes a drive means for
driving the reading means 104 in the direction of the radius of the
optical disc 102. This drive means 109 comprises, for example, a
traverse drive means 110 for driving the whole reading means 104 in
the direction of the radius of the optical disc, and a tracking
actuator 111 for minutely driving the objective lens 106 included
in the reading means 104, in the direction of the radius of the
optical disc.
[0104] Reference numeral 112 denotes a track cross detection means
for generating track cross pulses on the basis of playback signals
which are generated when the laser beam outputted from the reading
means 104 crosses the tracks on the optical disc 102. Reference
numeral 113 denotes a track cross direction detection means for
detecting the direction along which the laser beam from the reading
means 104 crosses the tracks on the optical disc. The track cross
detection means 112 or the track cross direction detection means
113 binarizes the tracking error signal outputted from the reading
means 104 with a hysteresis comparator or a comparator to generate
a track count signal TKC. Likewise, the track cross detection means
112 or the track cross direction detection means 113 generates a
non-on track signal OFTR from the envelope of the RF signal, and
generates a track cross direction signal according to the phase
relationship between the TKC and the OFTR, or generates a track
cross detection pulse by directly using the TKC or by latching the
TKC with the OFTR.
[0105] Reference numeral 114 denotes a rotation angle detection
means for detecting the rotation angle of the disc rotation means
103. The rotation angle detection means 114 generally utilizes a
signal called an FG pulse that is generated from the output of a
Hall element of a disc motor. As the FG signal outputs three pulses
for one rotation with a three-phase motor, rotation angle detection
in units of 60 degrees is possible by counting both of a rising
edge and a falling edge. Further, there are proposed a method of
performing more accurate rotation angle detection by
frequency-dividing the FG pulse, and a method of detecting the
rotation speed at an arbitrarily resolution by providing the disc
motor with a rotation speed detection means using an encoder.
[0106] Reference numeral 115 denotes a count means for counting the
number of track crosses including the direction, on the basis of
the output from the rotation angle detection means 105, and the
outputs from the track cross detection means 112 and the track
cross direction detection means 113. In the above-mentioned case
where the rotation angle can be detected at every 60 degrees, one
rotation is divided into six areas, and a signed track count is
obtained for each area.
[0107] Reference numeral 116 denotes a control means for processing
the signals supplied from the conversion means 108 and the count
means 115, and controlling the disc rotation means 103, the reading
means 104, the conversion means 108, and the drive means 109.
[0108] Next, the operation will be described. Initially, a
description will be given of a step in which the control means 116
sets a maximum rotation speed of the DVD-ROM player.
[0109] A step of detecting the track pitch of the optical disc 102
will be described taking, for example, a method of determining the
type of the information disc and selecting a standard track pitch
according to the information about the disc type. Usually, the
DVD-ROM player 101 can play plural types of information discs as
described above, and the required light source and the method for
generating a detection signal vary among the plural disc types.
Therefore, initially, the type of the loaded disc is determined by
various methods. For example, the loaded information disc is
discriminated between a ROM (CD-ROM/R, DVD-ROM/R) disc and a
rewritable disc (CD-RW), from the reflectivity of the information
disc, using a CD laser, on the basis of the amplitude of a focus
error signal obtained in focus search, and furthermore, it is
discriminated between a DVD disc and a CD disc, from the degree of
modulation of an RF signal, and thereafter, required light source
and signal path are selected. Finally, it is checked whether TOC
(TABLE OF CONTENTS) information can be read from the disc or not,
and further, it is checked whether the disc type selected from the
contents of the TOC information is correct or not. Then, the
standard value of the track pitch according to the disc type is
selected.
[0110] In a step of obtaining the result of counting by the count
means when the disc is rotated at the first rotation speed, the
drive means 104 is disabled, and the optical disc 102 is rotated at
the first rotation speed by controlling the disc rotation means
103. Then, the result of counting by the count means 115 is
captured. In this first embodiment, using a three-phase motor,
utilizing an FG signal outputted from a Hall element, the rotation
angle is detected at the rising and falling edges of the FG signal,
and the counted number of track crosses is obtained at every
rotation angle of 60 degrees. Further, in this first embodiment,
the first rotation speed is set at a sufficiently low speed which
does not cause vibration between the reading means 104 and the
optical disc 102, and the number of track crosses caused by only
the eccentricity between the optical disc 102 and the disc rotation
means 103 is measured.
[0111] Also in a step of obtaining the count of the count means
when the optical disc 102 is rotated with at least one rotation
speed that is higher than the first rotation speed, the number of
track crosses can be counted at every rotation angle of 60 degrees,
as in the step of obtaining the count of the count means when the
disc is rotated at the first rotation speed. In this first
embodiment, the count is obtained at the maximum rotation speed
that is set for every disc type of the DVD-ROM player.
[0112] Next, each of the counts obtained when the disc is rotated
at the first speed and the at least one speed higher than the first
speed is multiplied by the track pitch which is detected in the
track pitch detection step, thereby obtaining data of the track
cross amount. In this embodiment, data of the track cross amount at
every 60 degrees is calculated from the number of tracks counted at
every rotation angle of 60 degrees.
[0113] In a step of calculating the vibration amplitude of the
optical disc 102 with respect to the reading means 104, the track
cross amount detected at the first rotation speed is compared with
the track cross amount detected with the at least one rotation
speed higher than the first speed, and the vibration amplitude of
the information disc with respect to the reading means is
calculated on the basis of a difference between the track cross
amounts. In this first embodiment, a difference between the track
cross amount detected at the first rotation speed and the track
cross amount detected at the maximum rotation speed is obtained at
every rotation angle of 60 degrees, thereby calculating a track
cross component due to the vibration. Then, the vibration amplitude
is obtained on the assumption that the vibration is a sinusoidal
wave.
[0114] In a step of determining the maximum rotation speed,
comparison is carried out as to whether the previously obtained
vibration amplitude is lower than a reference value or not. When it
is lower than the reference value, the maximum rotation speed that
is set for every disc type is employed, and when it is higher than
the reference value, a rotation speed lower than the maximum
rotation speed is employed.
[0115] Then, reproduction of data is carried out at a speed lower
than the set maximum rotation speed.
[0116] Next, a description will be given of a case where vibration
of a CD-ROM is to be detected.
[0117] A CD-ROM disc loaded on the DVD-ROM player 101 is fixed to
the disc rotation means 103. Next, focus search is carried out with
a laser beam for CD-ROM, and the amplitude of a focus error signal
is measured. As a result, the loaded CD-ROM disc is judged as a ROM
disc because its reflectivity is relatively high. Next, the CD-ROM
disc is rotated at a predetermined speed by the disc rotation means
103, and the degree of modulation of an RF signal is measured. The
measured degree of amplitude is compared with a reference value,
whereby the CD-ROM disc is judged as a CD disc, whereby the result
of disc judgement is a CD-ROM. Also when a DVD-ROM disc is
employed, the disc is judged as a DVD-ROM disc in the same manner
as described above, and then it is checked whether the DVD-ROM disc
is a DVD-R4.7G (track pitch: 0.74 .mu.m) or a DVD-R3.9G (track
pitch: 0.8 .mu.m) by reading the TOC information, whereby the track
pitch can be detected.
[0118] Next, the CD-ROM disc is rotated at a sufficiently low
speed, 1200 rpm, which does not cause vibration between the disc
and the reading means 104. Then, the traverse drive means 110 and
the tracking actuator 111 are disabled, and the count of the count
means 115 is obtained at every rotation angle of 60 degrees. Since
no vibration occurs between the disc and the reading means 104, the
count due to only the eccentricity component between them is
obtained. For example, the count may be obtained by a method of
performing counting for plural rotations with one rotation as a
unit, and averaging the obtained counts, or a method of performing
counting for plural rotations as described above, and selecting,
from the obtained counts, plural counts which are not supposed to
be false counts.
[0119] Next, the CD-ROM disc is rotated at the maximum rotation
speed of the CD-ROM disc. In this example, the CD-ROM disc is able
to perform CAV playback at 24X(maximum)-speed, 12X-speed, and
6X-speed. Since the maximum rotation speed is 5000 rpm, the
12X-speed is 2500 rpm, and the 6X-speed is 1250 rpm, the count when
the disc is rotated at 5000 rpm is obtained.
[0120] Next, a difference between the counts obtained at 1200 rpm
and 5000 rpm for every rotation angle is calculated, whereby the
track count due to the vibration at 5000 rpm, excluding the
eccentricity component, is obtained.
[0121] Finally, the vibration amplitude of this disc is evaluated
from this track count and the track pitch, or the vibration speed
or vibration acceleration is evaluated from the track count, the
track pitch, and the rotation speed of 5000 rpm, and it is decided
whether the disc is to be rotated at the maximum rotation speed or
not, according to whether the vibration amplitude, or the vibration
speed, or the vibration acceleration is lower than the allowable
value or not. For example, when it is higher than the allowable
value, the maximum rotation speed is reduced to 2500 rpm of the
12X-speed.
[0122] As described above, according to the first embodiment, the
vibration amount, or vibration speed, or vibration acceleration is
evaluated considering the track pitch of the disc, and a maximum
rotation speed that is lower than the allowable vibration
amplitude, or vibration speed, or vibration acceleration of the
information disc recording/playback apparatus is decided.
Therefore, vibration detection can be carried out using a single
threshold value, independently of the type of the information
disc.
[0123] In this first embodiment, counting of the track crosses is
carried out at plural rotation speeds while detecting the rotation
angle, and a difference between them is calculated to obtain the
track count due to vibration. However, there may be employed a
method of simply counting the track crosses at plural rotation
speeds without detecting the rotation angle and then taking a
difference between them, or a method of counting the track crosses
at a single rotation speed without detecting the rotation
angle.
[0124] Furthermore, while in this first embodiment evaluation of
vibration is performed on the basis of a difference between the
count obtained at a low speed at which no vibration occurs and the
count obtained at the maximum rotation speed, it may be performed
on the basis of a difference between the count obtained at a
rotation speed at which vibration occurs and the count obtained at
the maximum rotation speed. Further, not the maximum rotation speed
but a rotation speed lower than the maximum rotation speed may be
employed. Furthermore, evaluation may be carried out at two or more
rotation speeds, and the playback speed may be set as follows: the
maximum rotation speed, a speed lower than the maximum rotation
speed, a speed lower than that speed, . . .
[0125] Moreover, in this first embodiment, the counted number of
track crosses is multiplied by the track pitch to obtain data of
the track cross amount, and the track cross amount due to vibration
is calculated by operating the track cross amount, and the
vibration amplitude is obtained on the basis of the track cross
amount due to vibration. However, as for the track pitch of the
disc, the value of the track pitch itself may be employed, or the
ratio of track pitches of plural discs may be employed.
Furthermore, when the number of track crosses due to vibration is
obtained by operating the result of counting, the number of track
crosses may be multiplied by the track pitch to obtain the track
cross amount due to vibration and, thereafter, the vibration
amplitude may be obtained. Alternatively, the vibration amount with
the number of track crosses as a unit may be obtained, and the
vibration amount may be multiplied by the track pitch to obtain the
vibration amplitude.
[0126] Furthermore, while in this first embodiment the vibration
amplitude is obtained and compared with a reference value, not the
vibration amplitude itself but a value in proportion to the
vibration amplitude or a value in proportion to the second power of
the vibration amplitude may be calculated to be compared with the
reference value. Further, the vibration speed or vibration
acceleration may be obtained instead of the vibration
amplitude.
[0127] While in this first embodiment detection of vibration of a
CD-ROM disc is described, vibrations of discs having different
track pitches, such as a DVD and a DVD-R3.9G, can be detected in
like manner as described above.
[0128] While in this first embodiment a DVD-ROM player capable of
playing CD-ROM, DVD-ROM, DVD-R3.9G, and DVD-R4.7G is described as
an example, any information disc player may be employed as long as
it can play plural kinds of information discs having different
track pitches.
[0129] Furthermore, while in this first embodiment a DVD-ROM player
is described as an example, the present invention is applicable to
a case where a maximum recording speed at recording is set in other
writable recording/playback apparatuses such as CD-R, CD-RW, and
DVD-R.
[0130] (Embodiment 2)
[0131] Hereinafter, an information disc recording/playback
apparatus and a vibration detection method for the information disc
recording/playback apparatus according to a second embodiment of
the present invention will be described, taking a DVD-ROM player as
an example, with reference to FIG. 2.
[0132] In FIG. 2, the same reference numerals as those shown in
FIG. 1 denote the same or corresponding parts, and reference
numeral 201 denotes a track cross speed detection means for
detecting a track cross speed on the basis of the output from the
track cross detection means 112.
[0133] The count means 115 counts the track count pulses while
detecting the direction when the track cross speed is lower than a
predetermined value, and counts the track count pulses without
detecting the direction when the track cross speed is higher than
the predetermined value, on the basis of the output from the track
cross speed detection means 201. When it is switched to "without
direction detection", the track cross direction can be known on the
basis of the direction obtained when counting with direction
detection has been most recently carried out.
[0134] The maximum speed at which track counting with direction
detection can be carried out depends on the track counting method
or the disc type.
[0135] For example, when tracking error detection is carried out by
the three-beam method for a CD or by the phase difference method
for a DVD, generally the three-beam method is able to perform
direction detection at a higher speed. Accordingly, a threshold
value for determining as to whether track counting is to be carried
out with direction detection or not may be set for each disc type,
or it may be set adaptively to a disc of the lowest speed at which
track counting with direction detection is possible.
[0136] As described above, according to the second embodiment, the
track cross speed detection means 201 is provided, and the track
counting method is changed by detecting the track cross frequency.
Therefore, even when detection of the track cross direction is
difficult because of the change in the track cross speed, track
counting can be performed with accuracy, whereby accurate vibration
detection can be performed at all times.
[0137] (Embodiment 3)
[0138] Hereinafter, an information disc recording/playback
apparatus and a vibration detection method for the information disc
recording/playback apparatus according to a third embodiment of the
present invention will be described, taking a DVD-ROM player as an
example, with reference to FIGS. 3 and 6.
[0139] In FIG. 3, the same reference numerals as those shown in
FIG. 1 denote the same or corresponding parts, and reference
numeral 301 denotes a zero cross area detection means for detecting
an area where the track cross speed has the lowest value. The
rotation angle detection means 114 usually employs a signal called
an FG pulse that is generated from the output of a Hall element of
a disc motor. Since the FG signal outputs three pulses for one
rotation with a three-phase motor, rotation angle detection in
units of 60 degrees can be carried out by counting both of rising
and falling edges. In this third embodiment, a description will be
given of a case where rotation angle detection is performed in
units of 60 degrees using the FG pulses.
[0140] The zero cross area detection means 301 detects two areas
each including a position where the track cross speed has the
lowest value. For example, there may be employed a method of
detecting areas where the track cross speed has the lowest value by
using the track cross speed detection means 112, or a method of
detecting, as zero cross areas, an area where the absolute value of
the track count has the lowest value, and an area on a diagonal
line with respect to the area from among the six-divided areas.
[0141] Hereinafter, a description will be given of the reason why
the area where the absolute value of the track count has the lowest
value and the area on a diagonal line with respect to this area,
among the six-divided areas, are zero cross areas.
[0142] FIG. 6 is a graph illustrating the amount of displacement of
the count by the count means 115 at every rotation angle, which
displacement is caused by vibration or eccentricity. A count DAT[n]
in a zero cross area within a range of .phi.=0.about.60.degree.,
which is a signed count obtained when performing direction
detection, is represented by
DAT[n]=T.sub.ccos(.phi.)-cos(.phi.-60) (Formula 23)
[0143] Likewise, counts DAT[n] and DAT[n+1] in two areas which are
not zero cross areas, within a range of .phi.=0.about.60.degree.,
are represented by
DAT[n+1] T.sub.ccos(.phi.+60)-T.sub.ccos(.phi.) (Formula 24)
DAT[n+2] T.sub.ccos(.phi.+120)-T.sub.ccos(.phi.+60) (Formula
25)
[0144] A maximum value of .vertline.DAT[n].vertline. within this
range is represented by when .phi.=0.about.60.degree.,
.vertline.DAT[n].vertline.=0.5T.sub.c
[0145] Likewise, minimum values of DAT[n+1] and DAT[n+2] are
represented by
[0146] when .phi.=0.degree.,
.vertline.DAT[n+1].vertline.=0.5T.sub.c
[0147] when .phi.=60.degree.,
.vertline.DAT[n+2].vertline.=0.5T.sub.c
[0148] According, the following relationship always holds.
.vertline.DAT[n].vertline..gtoreq..vertline.DAT[n+1],.vertline.DAT[n+2].ve-
rtline.
[0149] Likewise, when the count is obtained without performing
direction detection, since only the number of track crosses is
counted disregarding the track cross direction, a count DAT[n] in a
zero cross area, within a range of .phi.=0.about.60.degree., with
cos(0) as a boundary, is represented by
DAT[n]=.vertline.T.sub.c(cos(0)-cos(.phi.))
.vertline.+.vertline.T.sub..ch- i.(cos(.phi.-60)-cos(0)).vertline.
(Formula 26)
[0150] and, as in the above-described case of performing direction
detection, counts in two areas which are not the zero cross areas
are represented by
DAT[n+1]=T.sub.ccos(.phi.+60)-T.sub.ccos(.phi.) (Formula 27)
DAT[n+2]=T.sub.ccos(.phi.+120)-T.sub.ccos(.phi.+60) (Formula
28)
[0151] A maximum value of .vertline.DAT[n].vertline. within this
range is represented by
[0152] when .phi.=0, 60.degree.,
.vertline.DAT[n].vertline.=0.5T.sub.c
[0153] Likewise, minimum values of DAT[n+1] and DAT[n+2] are
represented by
[0154] when .phi.=0.degree.,
.vertline.DAT[n+1]=0.5T.sub.c
[0155] when .phi.=60.degree.,
.vertline.DAT[n+2].vertline.=0.5T.sub.c
[0156] According, also in this case, the following relationship
always holds.
.vertline.DAT[n].vertline..gtoreq..vertline.DAT[n+1],.vertline.DAT[n+2].ve-
rtline.
[0157] Next, an example of specific operation according to the
third embodiment will be described.
[0158] Initially, the optical disc 102 is rotated at a
predetermined rotation speed. After the traverse drive means 110
and the tracking actuator 111 are disabled, the count of the count
means 115 is obtained for every rotation angle of 60 degrees. At
this time, the count is obtained by any of the following methods: a
method of obtaining the count with direction detection for an area
which is judged as a zero cross area by the zero cross area
detection means 301 while obtaining the count without direction
detection for other areas; a method of obtaining the count with
direction detection and the count without direction detection
separately, and selecting the count with direction detection for
the zero cross area while selecting the count without direction
detection for other areas; and a method of obtaining the count with
direction detection and the count without direction detection at
the same time, and selecting the count with direction detection for
the zero cross area while selecting the count without direction
detection for other areas. Further, an area that adopts the data
without direction detection can obtain the same count as that with
direction detection by adding the sign of a just previous area that
adopts the data with direction detection, or by adding the sign of
a further previous area if the just previous area adopts the data
without direction detection.
[0159] As described above, according to the third embodiment of the
present invention, since the zero cross area detection means 301 is
provided, the track cross, detection method is switched between the
area where the track cross speed has the lowest value and the other
areas, among the areas divided with the rotation angle obtained by
the rotation angle detection means 114, and track counting is
carried out with direction detection for the area where the track
cross speed has the lowest value while it is carried out without
direction detection for the other areas, whereby the optimum track
counting method can be selected according to variations in the
track cross speed, and accurate vibration detection can be carried
out at all times.
[0160] (Embodiment 4)
[0161] Hereinafter, an information disc recording/playback
apparatus and a vibration detection method for the information disc
recording/playback apparatus according to a fourth embodiment of
the present invention will be described taking a DVD-ROM player as
an example, with reference to FIG. 1.
[0162] Since the fundamental construction of the apparatus is
identical to that of the first embodiment, repeated description is
not necessary. Next, an example of specific operation of this
fourth embodiment will be described employing the rotation angle
detection means 114.
[0163] A DVD-ROM disc loaded on the DVD-ROM player 101 is fixed to
the disc rotation means 103. Next, focus search is carried out with
a laser for CD-ROM, and the amplitude of a focus error signal is
measured. As a result, the DVD-ROM disc is judged as a ROM disc
because its reflectivity is relatively high. Next, the DVD-ROM disc
is rotated at a predetermined speed by the disc rotation means 103,
and the degree of modulation of an RF signal is measured. The
measured degree of modulation is compared with a reference value,
whereby the disc is judged as a DVD disc. Consequently, the disc
judgement result is a DVD-ROM.
[0164] In this fourth embodiment, the DVD-ROM disc is able to
perform 8X-speed playback at 4590 rpm (maximum speed), 5X-speed
playback at 2870 rpm, and 2.5X-speed playback at 1435 rpm, and a
low speed at which no vibration occurs is 1435 rpm. Vibration
detection is carried out at 3000 rpm and 400 rpm, and it is judged
whether or not the detected vibration amounts are lower than an
allowable vibration amount at the 5X-speed and the 8X-speed,
respectively. Further, the allowable vibration amount is 100
.mu.m.
[0165] Initially, the DVD-ROM disc is rotated at 1435 rpm that is a
sufficiently low speed at which no vibration occurs between the
disc and the reading means 104. After the traverse drive means 110
and the tracking actuator 111 are disabled, the count of the count
means 115 is obtained at every rotation angle of 60 degrees. Since
no vibration occurs between the disc and the reading means 104, the
count due to only the eccentricity component between the disc and
the reading means 104 is obtained. For example, the count may be
obtained by a method of performing counting for plural rotations
with one rotation as a unit, and averaging the obtained counts, or
a method of performing counting for plural rotations as described
above, and selecting, from the obtained counts, plural counts which
are not supposed to be false counts.
[0166] For example, it is assumed that the data measured for four
rotations with direction detection in each of the six-divided
areas, and the average of the measured data in each area are as
follows:
2TABLE 1 counts at 1400 rpm No. area [0] area [1] area [2] area [3]
area [4] area [5] 1 57 39 -17 -57 -35 18 2 59 39 -20 -55 -35 18 3
57 37 -18 -57 -34 22 4 57 39 -18 -59 -33 14 average 57.5 38.5 -18.3
-57.0 -34.3 18.0
[0167] Likewise, counting is carried out at 3000 rpm. When it is
assumed that the counts at 3000 rpm are as follows:
3TABLE 2 counts at 3000 rpm No. area [0] area [1] area [2] area [3]
area [4] area [5] 1 71 49 -21 -69 -48 18 2 71 49 -22 -69 -49 19 3
72 49 -22 -69 -49 18 4 72 51 -20 -71 -50 18 average 71.5 49.5
-21.25 -69.5 -49 18.25
[0168] a difference between the @ average values of the track
counts obtained at 1435 rpm and 3000 rpm in each area is
represented by
4TABLE 3 counts at 3000 rpm-1400 rpm DAT [0] DAT [1] DAT [2] DAT
[3] DAT [4] DAT [5] 14.0 11.0 -3.0 -12.5 -14.8 0.3
[0169] and, these counts are track counts due to vibration.
[0170] In order to obtain the vibration amount from the data shown
in (Table 3), these data are substituted into (Formula 12) and
(Formula 13), whereby 12 pieces of data are obtained as
follows:
5TABLE 4 calculated vibration amounts (3000 rpm-1400 rpm) vibration
vibration vibration vibration vibration vibration amount amount
amount amount amount amount 1 [0] 1 [1] 1 [2] 1 [3] 1 [4] 1 [5] 44
44 39 48 52 48 44 41 57 43 50 39
[0171] By averaging these 12 pieces of data, the vibration amount
is obtained as follows.
[0172] vibration amount=46 tracks
[0173] Further, since this disc is a DVD-ROM disc, the vibration
amount is multiplied by the track pitch of 0.74 .mu.m, whereby the
vibration amplitude is obtained as follows.
[0174] vibration amplitude=34.04 [.mu.m]
[0175] Since the allowable maximum vibration amount of the system
is 100 .mu.m and the obtained vibration amplitude is lower than the
allowable value, the disc can be rotated at the 5X-speed, i.e.,
2870 rpm.
[0176] Next, counting is carried out at 4000 rpm. When it is
assumed that the counts at 4000 rpm are as follows:
6TABLE 5 counts at 4000 rpm No. area [0] area [1] area [2] area [3]
area [4] area [5] 1 -61 86 133 53 -78 -132 2 -62 86 132 53 -78 -133
3 -61 85 132 56 -78 -133 4 -62 82 133 56 -75 -133 average -61.5
84.75 132.5 54.5 -77.25 -132.75
[0177] a difference between the average values of the track counts
obtained at 1435 rpm and 3000 rpm in each area is represented
by
7TABLE 6 counts at 4000 rpm-1400 rpm DAT [0] DAT [1] DAT [2] DAT
[3] DAT [4] DAT [5] -119.0 46.3 150.8 111.5 -43.0 -150.8
[0178] and, these counts are track counts due to vibration.
[0179] In order to obtain the vibration amount from the data shown
in (Table 3), these data are substituted into (Formula 12) and
(Formula 13), whereby 12 pieces of data are obtained as
follows:
8TABLE 7 calculated vibration amounts (4000 rpm-1400 rpm) vibration
vibration vibration vibration vibration vibration amount amount
amount amount amount amount 1 [0] 1 [1] 1 [2] 1 [3] 1 [4] 1 [5] 171
154 156 159 155 159 159 162 155 156 168 154
[0180] By averaging these 12 pieces of data, the vibration amount
is obtained as follows.
[0181] vibration amount=159 tracks
[0182] Further, since this disc is a DVD-ROM disc, the vibration
amount is multiplied by the track pitch of 0.74 .mu.m, whereby the
vibration amplitude is obtained as follows.
[0183] vibration amplitude=117.66 [.mu.m]
[0184] Since the allowable maximum vibration amount of the system
is 100 .mu.m and the obtained vibration amplitude is higher than
the allowable value, the disc cannot be rotated at the 8X-speed,
i.e., 4590 rpm, and therefore, the maximum rotation speed is set at
the 5X-speed.
[0185] Hereinafter, a description will be given of the reason why
the vibration amount, the vibration speed, and the vibration
acceleration can be expressed by (Formula 12).about.(Formula 17),
using the signed counts obtained with direction detection.
[0186] When the track count area is divided into six sections at
every 60 degrees and counting is carried out for each section, the
count in each section is represented by (Formula 29), assuming that
the respective sections are 0.about.5, the vibration amount is Tc,
and the phase angle of the track displacement amount at a starting
point in section 0 is .phi..
DAT[n]=T.sub.ccos(30n+.phi.)-T.sub.ccos(30n+.phi.-60) (Formula
29)
[0187] When the data in the respective sections 0.about.5 are
DAT[0]=a, DAT[1]=b, DAT[2]=c, DAT[3]=-a, DAT[4]=-b, DAT[5]=-c, from
(Formula 29), DAT[0] is represented by 7 DAT [ 0 ] = T c ( cos ( )
- cos ( - 60 ) ) = T c ( cos ( ) - cos ( ) cos ( 60 ) + sin ( ) sin
( 60 ) ) = T c ( 1 2 cos ( ) + 3 2 sin ( ) ) = T c sin ( + 1 ) (
Formula 30 ) Since sin ( 1 ) = 3 2 , cos ( 1 ) = 1 2 , 1 = 60 DAT [
0 ] = T c sin ( + 60 ) = a
[0188] Likewise, DAT[1] is represented by 8 DAT [ 0 ] = T c ( cos (
+ 60 ) - cos ( ) ) = T c ( cos ( ) cos ( 60 ) - sin ( ) sin ( 60 )
- cos ( ) ) = T c ( 1 2 cos ( ) - 3 2 sin ( ) ) = T c sin ( + 2 )
Since sin ( 2 ) = 3 2 , cos ( 2 ) = 1 2 , 2 = - 60 DAT [ 1 ] = T c
sin ( - 60 ) = b ( Formula 31 )
[0189] From (Formula 30), 9 sin ( + 60 ) = a T c ( Formula 32 )
[0190] Then, (Formula 31) is represented by 10 DAT [ 1 ] = T c sin
( + 60 - 120 ) = T c ( sin ( + 60 ) cos ( - 120 ) + sin ( - 120 )
cos ( + 60 ) ) = T c ( - 1 2 sin ( + 60 ) - 3 2 cos ( + 60 ) ) = T
c ( - 1 2 sin ( + 60 ) 3 2 1 - sin 2 ( + 60 ) ) = T c ( - 1 2 a T c
3 2 1 - ( a T c ) 2 ) = b ( Formula 33 )
[0191] Accordingly, 11 - 1 2 a 3 2 T c 2 - a 2 = b 3 2 T c 2 - a 2
= b + 1 2 a 3 4 ( T c 2 - a 2 ) = b 2 + ab + 1 4 a T c = 2 3 a 2 +
ab + b 2 ( Formula 34 )
[0192] Likewise, since DAT[0]=a, DAT[2]=c, 12 T c = 2 3 a 2 - ac +
c 2 ( Formula 35 )
[0193] and, therefore, (Formula 12) and (Formula 13) are derived
from (Formula 34) and (Formula 35).
[0194] Furthermore, the track cross due to the eccentricity or
vibration is represented by a sinusoidal wave as follows, using the
Tc, phase angle .phi., and angular velocity .omega..
f(t)=T.sub.ccos(.omega.t+.phi.) (Formula 36)
[0195] Then, the absolute value of the track cross speed is
obtained by differentiating (Formula 36) as follows. 13 | f ( t ) t
| = T c | sin ( t + ) | ( Formula 37 )
[0196] Since .omega.=2.pi.f, and f=Vrpm/60 (Vrpm: present rotation
speed [rpm]), 14 | f ( t ) t | = 2 fT c | sin ( t + ) | = 2 V rpm
60 T c | sin ( t + ) | ( Formula 38 )
[0197] Since (Formula 38) becomes maximum when
.vertline.sin(.omega.t+.phi.).vertline.=1 (Formula 39)
[0198] (Formula 14) and (Formula 15) are derived from (Formula 34)
and (Formula 35), respectively.
[0199] Furthermore, the absolute value of the track cross
acceleration is obtained by differentiating (Formula 38) as
follows. 15 | 2 f ( t ) t 2 | = ( 2 V rpm 60 ) 2 | cos ( t + ) | (
Formula 40 )
[0200] Since (Formula 27) becomes maximum when
cos(.omega.t+.phi.)=1 (Formula 41)
[0201] (Formula 16) and (Formula 17) are derived from (Formula 34)
and (Formula 35), respectively.
[0202] As described above, according to the fourth embodiment of
the present invention, when the vibration amplitude, or vibration
speed, or vibration acceleration is evaluated considering the track
pitch of the optical disc 102, it is calculated at every
predetermined rotation angle and an average of the results of
calculation is obtained, and a maximum rotation speed that is lower
than the allowable vibration amplitude, or vibration speed, or
vibration acceleration of the information disc recording/playback
apparatus is determined on the basis of the average. Therefore,
vibration detection can be carried out more accurately as compared
with the first embodiment, using a single threshold value,
independently of the type of the information disc.
[0203] While in this fourth embodiment, setting of the maximum
rotation speed of the DVD-ROM disc is described, the maximum
rotation speeds of other types of discs having different track
pitches, such as a CD-ROM disc having a track pitch of 1.6 .mu.m or
a DVD-R3.9G disc having a track pitch of 0.8 .mu.m, can also be
obtained by judging as to whether the measured maximum vibration
amount is lower than the allowable one, using the standard track
pitch of each disc and the vibration amount.
[0204] Further, while in this fourth embodiment the vibration
amount is obtained on the basis of the average of 12 pieces of
data, the vibration amount may be obtained using the average of m
pieces of central values selected from the 12 pieces of data which
are arranged in the order of size, or using a value in proportion
to the average.
[0205] Furthermore, while in this fourth embodiment the maximum
playback speed is set on the basis of the vibration amplitude, the
maximum playback speed may be set using a value in proportion to
the vibration amplitude or a value in proportion to the second
power of the vibration amplitude. Alternatively, the maximum
playback speed may be set on the basis of the vibration speed or a
value in proportion to the vibration speed or the second power of
the vibration speed, using (Formula 14) and (Formula 15) as well as
the disc rotation speed. Further, the maximum playback speed may be
set on the basis of the vibration acceleration speed or a value in
proportion to the vibration acceleration speed or the second power
of the vibration acceleration speed, using (Formula 16) and
(Formula 17) as well as the disc rotation speed.
[0206] Moreover, while in this fourth embodiment the maximum
playback speed is set on the basis of the data obtained for four
rotations each rotation being divided into six areas, the maximum
playback speed may be obtained by measuring data corresponding to
continuous two or more areas.
[0207] (Embodiment 5)
[0208] Hereinafter, an information disc recording/playback
apparatus and a vibration detection method for the information disc
recording/playback apparatus according to a fifth embodiment of the
present invention will be described taking a DVD-ROM player as an
example, with reference to FIG. 4.
[0209] In FIG. 4, the same reference numerals as those shown in
FIG. 1 denote the same or corresponding parts, and reference
numeral 116a denotes a control means having a linear speed
detection means 401 and a playback speed detection means 402. The
linear speed detection means 401 detects the linear speed of the
disc. For example, the linear speed is detected as follows. An
address value at a certain radial position is previously read,
one-track jumping is carried out, an address value at the
destination of the track jumping is read, and a difference between
the address values is obtained as the linear speed. Alternatively,
the length of one rotation of the disc is obtained from a radial
position, and the linear speed of the disc is obtained on the basis
of the radio of the length to the difference between the previously
obtained address values for one rotation. The playback speed
detection means 402 detects the current playback speed. For
example, the current playback speed is obtained from the cycle of a
PLL which generates a data playback clock, or it is obtained on the
basis of the cycle of a frame clock which is outputted for every
frame of data.
[0210] Next, a description will be given of the operation for
obtaining the track pitch.
[0211] Generally, assuming that the track pitch of the disc is Tp,
the linear speed is V1, the current address position is Ad, the
current radial position is r, the radial position at the innermost
radius is R0, and the address value included in the unit time is
Adunit, the following relationship holds. 16 ( r 2 - R 0 2 ) T p =
V 1 Ad Ad unit ( Formula 42 )
[0212] Further, assuming that the current rotation speed is Vrpm,
the playback speed V2 at the radial position r is represented by 17
V 2 = 2 r V 1 V rpm 60 ( Formula 43 )
[0213] Therefore, assuming that the linear speed is V1, the current
address value is Ad, and the current rotation speed is Vrpm, the
track pitch Tp is represented by 18 T p = [ ( 60 V 1 V 2 2 V rpm )
2 - R 0 2 ] Ad unit V 1 Ad ( Formula 44 )
[0214] Accordingly, the track pitch Tp can be obtained by further
measuring the current playback speed V2 at a certain address
Ad.
[0215] Although the address Ad at which the current playback speed
V2 is obtained may be an arbitrary address, when measurement is
carried out at an outer radial position, the accuracy is
improved.
[0216] For example, assuming that a CD-ROM disc has
[0217] linear speed V1=1.25 m/s
[0218] playback speed measurement address AD=60:00:00
=270000[frame]
[0219] rotation speed=5300 rpm
[0220] playback speed=23.8X
[0221] according to the standard of CD-ROM,
[0222] Adunit =75[frame]
[0223] R0=0.0249 [m]
[0224] are obtained, and these values are substituted into (Formula
44) to obtain the track pitch as follows.
[0225] Tp=1.573 [.mu.m]
[0226] As described above, according to the fifth embodiment, when
a move distance detection means for detecting the move distance of
the reading means 104 is provided, accurate vibration detection can
always be carried out by measuring the accurate track pitch, even
when the track pitch is different from the standard value that is
set for each disc type. Furthermore, when the track pitch is
obtained from the linear speed, address value, and playback speed,
accurate vibration detection can always be carried out by measuring
the accurate track pitch, even when the track pitch is different
from the standard value that is set for each disc type, with
reduced cost, without the necessity of adding a move distance
detection means.
[0227] While in this fifth embodiment the track pitch of a CD-ROM
disc is obtained, the track pitches of discs based on other
standards, such as a DVD or a DVD-R3.9G, can be obtained in like
manner as described above.
[0228] Further, while in this fifth embodiment the track pitch is
obtained from the linear speed, address value, and playback speed,
the track pitch may be obtained as follows. As shown in FIG. 10,
the control means 116b is provided with a move distance detection
means 403 for detecting the move distance of the reading means 104,
and the reading means 104 is moved while counting the number of
tracks, and the track pitch is obtained as follows.
[0229] Tp=move distance/number of crossed tracks
[0230] (Embodiment 6)
[0231] Hereinafter, an information disc recording/playback
apparatus and a vibration detection method for the information disc
recording/playback apparatus according to a sixth embodiment of the
present invention will be described taking a DVD-ROM player as an
example, with reference to FIG. 5.
[0232] In FIG. 5, the same reference numerals as those shown in
FIG. 1 denote the same or corresponding parts, and reference
numeral 501 denotes a variable filter means having a function of
shaping the track cross pulses detected by the track cross
detection means 112 so that the pulses whose widths are narrower
than a predetermined value, among the detected pulses, are not
counted.
[0233] Hereinafter, a method of actually setting the variable
filter means 501 will be described.
[0234] When setting the variable filter means 501, initially, the
total number of track crosses for one or more rotation is counted
by the method in which the track cross direction is not detected.
At this time, it is necessary to set an initial set value of the
variable filter means 501, and usually, this initial value must be
set at such a value that the minimum track count pulse width
corresponding to the maximum track cross speed is surely counted
when an eccentricity between the disc and the turn table and a
maximum vibration amplitude estimated at its rpm occur.
[0235] Assuming that the counted number of track crosses is 4Tc per
rotation, the maximum track cross speed can be obtained as
follows.
[0236] Initially, the track cross due to the eccentricity or
vibration is expressed by a sinusoidal wave. Using the
above-mentioned Tc, phase angle .phi., and angular velocity
.omega., the track
[0237] cross is represented by (Formula 45)
f(t)=T.sub.ccos(.omega.t+.phi.) (Formula 45)
[0238] Then, the absolute value of the track cross speed is
obtained by differentiating (Formula 32) as follows. 19 | f ( t ) t
| = T c | sin ( t + ) | ( Formula 46 )
[0239] Since .omega.=2.pi.f, and f=Vrpm/60 (Vrpm: current rotation
speed [rpm]), 20 | t ( t ) t | = 2 fT c | sin ( t + | = 2 V rpm 60
T c | sin ( t + ) | ( Formula 47 )
[0240] Accordingly, the maximum track cross speed is represented by
21 maximum track cross speed = 2 V rpm 60 T c ( Formula 48 )
[0241] and, the maximum track cross speed can be obtained from the
value of Tc.
[0242] The minimum track count pulse width is calculated on the
basis of the maximum track cross speed. Assuming that the maximum
track cross speed is Vmax[tracks/s], as two positive/negative
pulses are outputted per track, the minimum track count pulse width
is represented by 22 minimum track count pulse width = 1 2 V max [
s ] ( Formula 49 )
[0243] Thereby, the minimum track count pulse width of the variable
filter means 501 is set. For example, when the total number of
counted tracks per rotation at 3000 rpm is 287, the maximum track
cross speed is represented as follows:
[0244] Initially, since
T.sub.c=287/4=71.75
[0245] and, from (Formula 18),
Vmax =22.54 kHz
[0246] and, therefore, the minimum track count pulse width is 22.18
.mu.s from (Formula 49).
[0247] The variable filter means 501 is set on the basis of this
value so that pulses whose widths are narrower than the minimum
track count pulse obtained by the above calculation are also
counted, considering variations in the duty ratio of the normal
pulse width, or the like.
[0248] In this sixth embodiment, the variable filter means 501 is
set so that a pulse having a width of up to 5.54 .mu.s, which is
one fourth of 22.18 .mu.s, is counted as a track cross signal.
[0249] During high-speed driving, the duty ratio of the track count
pulse might significantly vary due to an influence of vibration in
the focusing direction, a reduction in the amplitude level of the
detection signal for track counting, or the like. In this case, the
variable filter means 501 may be set so that a pulse having a
narrower width is counted if driving at a speed higher than a
predetermined value is expected, while in the above example a value
obtained by dividing the calculated minimum track count pulse width
by a predetermined value is employed as a set value of the filter
means 501.
[0250] When the track counting is performed by the method in which
a signed count is outputted because direction detection is carried
out, the calculation method is somewhat different from that
mentioned above. For example, in the system of outputting rotation
angle information obtained by dividing one rotation into six areas,
assuming that the count in each area for one rotation is
[0251] DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
[0252] (when n>5, n=n mod 6 (a remainder of n being divided by
6), the maximum track cross speed becomes as represented by
(Formula 19) or (Formula 20). Thereby, data of plural maximum track
cross speeds are obtained, and the minimum track count pulse width
may be set similarly by using the average of these data, or the
average of m pieces of central values of these data, or the
like.
[0253] As described above, according to the sixth embodiment of the
present invention, setting of the track cross filter by the
variable filter means 501 is carried out on the basis of the track
cross count and the current rpm, so that the pulses whose widths
are narrower than a predetermined value are not counted. Therefore,
even when the track cross speed varies significantly due to the
eccentricity or vibration of the disc, track counting most suitable
for vibration detection can be accurately carried out at all
times.
[0254] Furthermore, setting of the minimum track count pulse width
may be carried out only once before obtaining the track count for
detecting the vibration amount at each rotation speed, or it may be
carried out every time the data (count) for detecting the vibration
amount is obtained.
[0255] (Embodiment 7)
[0256] Hereinafter, an information disc recording/playback
apparatus and a vibration detection method for the information disc
recording/playback apparatus according to a seventh embodiment of
the present invention will be described taking a DVD-ROM player as
an example, with reference to FIGS. 5 and 6.
[0257] Usually, a general purpose microcomputer having a relatively
small size is employed as a control means for computer peripheral
equipment such as a DVD-ROM player. Such microcomputer is basically
adaptive to integer arithmetic only, and therefore, floating-point
arithmetic or square root trigonometric function must be dealt with
by software.
[0258] In the calculation formula (Formula 19) or (Formula 20)
which is employed when the track counting is carried out by the
method in which a signed count is outputted because direction
detection is carried out as described for the sixth embodiment, it
is necessary to obtain square roots, resulting in a problem that
the number of program steps and the time required for arithmetic
are increased in the system as described above. Therefore, in this
case, assuming that
[0259] DAT[n]=DAT[0],DAT[1],DAT[2],DAT[3],DAT[4],DAT[5]
[0260] (when n>5, n=n mod 6 (a remainder of n being divided by
6), and the rotation speed of the disc rotation means is
Vrpm[rpm],
4T.sub.c=.vertline.DAT[0].vertline.+.vertline.DAT[1].vertline.+.vertline.D-
AT[2].vertline.+.vertline.DAT[3].vertline.+.vertline.DAT[4].vertline.+.ver-
tline.DAT[5].vertline. (Formula 50)
[0261] 23 maximum track cross speed = 2 V rpm 60 T c 1 cos 6 = 2 V
rpm 60 T c 2 3 ( Formula 51 )
[0262] and, therefore, the maximum track cross speed can be
calculated with reduced number of program steps and reduced
arithmetic time, and the variable filter means can be set on the
basis of the maximum track cross speed.
[0263] This is explained as follows with reference to FIG. 6.
[0264] FIG. 6 is a graph illustrating the amount of displacement of
the count at every rotation angle, which displacement is caused by
vibration or eccentricity.
[0265] Initially, the track cross due to eccentricity or vibration
is expressed as a sinusoidal wave, in like manner as described for
the sixth embodiment. Using the Tc, phase angle .phi., and angular
speed .omega., the track cross is represented by 24 sin ( + 60 ) =
a T c ( Formula 52 )
[0266] Then, this is divided at every 60 degrees by dividing one
rotation into six sections, as shown in FIG. 6. In FIG. 6, 601
shows a waveform when .phi.=0, and 602 shows a waveform when
.phi.=30.degree..
[0267] For example, when .phi.=0, assuming that the data
corresponding to 0.about.60.degree., 60.about.120.degree.,
120.about.180.degree., . . . are DAT[0], DAT[1], DAT[2], . . . ,
respectively, the respective data are represented as follows. 25
DAT [ 0 ] = T ( cos ( 60 ) - cos ( 0 ) ) = - 1 2 T c DAT [ 1 ] = T
c ( cos ( 120 ) - cos ( 60 ) ) = - T c DAT [ 2 ] = T c ( cos ( 180
) - cos ( 120 ) ) = - 1 2 T c DAT [ 3 ] = T c ( cos ( 240 ) - cos (
180 ) ) = 1 2 T c DAT [ 4 ] = T c ( cos ( 300 ) - cos ( 240 ) ) = T
c DAT [ 5 ] = T c ( cos ( 360 ) - cos ( 300 ) ) = 1 2 T c ( Formula
53 )
[0268] In this case, the Tc calculated from (Formula 21) becomes
the same as the original value of the Tc.
[0269] However, in the case where the boundary of the areas divided
at every 60 degrees as described above does not agree with the
position where the track move direction is inverted (in the case of
the waveform 601 when .phi.=0, the position 603 or 604), the Tc
calculated by (Formula 21) becomes smaller than the original Tc,
and the calculated maximum track cross speed also becomes lower
than the original value. When the Tc takes the smallest value, the
waveform and divided-area as shown by 602 are obtained when
.phi.=-30.degree.. At this time, the respective data are
represented as follows. 26 DAT [ 0 ] = T ( cos ( 30 ) - cos ( - 30
) ) = 0 DAT [ 1 ] = T c ( cos ( 90 ) - cos ( 30 ) ) = - 3 2 T c DAT
[ 2 ] = T c ( cos ( 150 ) - cos ( 90 ) ) = - 3 2 T c DAT [ 3 ] = T
c ( cos ( 210 ) - cos ( 150 ) ) = 0 DAT [ 4 ] = T c ( cos ( 270 ) -
cos ( 210 ) ) = 3 2 T c DAT [ 5 ] = T c ( cos ( 330 ) - cos ( 270 )
) = 3 2 T c ( Formula 54 )
[0270] Therefore, the Tc calculated from (Formula 21) becomes 0.866
times the original Tc. Accordingly, when the track counting is
carried out by the method in which a signed count is outputted
because direction detection is carried out, a value smaller than
the original Tc, i.e., 0.866 times the original Tc at the worst, is
calculated. Considering this effect, when calculating the maximum
track cross speed on the basis of the Tc calculated from (Formula
21), (Formula 22) represents the maximum track cross speed
including the expected error.
[0271] As described above, according to the seventh embodiment, the
maximum track cross speed including an expected error is calculated
on the basis of the signed track cross count and the current rpm,
and the track cross filter is set on the basis of the maximum track
cross speed. Therefore, track counting most suitable for vibration
detection can be accurately carried out at all times, without
necessity of performing additional counting without signs or
calculating square roots which require many program steps.
[0272] (Embodiment 8)
[0273] Hereinafter, an information disc recording/playback
apparatus and a vibration detection method for the information disc
recording/playback apparatus according to an eighth embodiment of
the present invention will be described taking a DVD-ROM player as
an example, with reference to FIG. 5. The fundamental construction
is identical to that shown in FIG. 5 and, therefore, the
distinctive operation of this eighth embodiment will be mainly
described hereinafter.
[0274] When setting the variable filter means 501, initially, the
total number of track crosses for one or more rotation is counted
by the method in which the track cross direction is not detected.
At this time, it is necessary to set an initial set value of the
variable filter means 501, and usually, this initial value must be
set at such a value that the minimum track count pulse width
corresponding to the maximum track cross speed is surely counted
when an eccentricity between the disc and the turn table and a
maximum vibration amplitude estimated at its rpm occur.
[0275] Assuming that the counted number of track crosses is 4Tc per
rotation, the maximum track cross speed is represented by (Formula
55), using the Tc, phase angle .phi., and angular velocity .omega..
27 maximum track cross speed = 2 V rpm 60 T c ( Formula 55 )
[0276] On the basis of this maximum track cross speed, the minimum
track count pulse width is calculated. Assuming that the maximum
track cross speed is Vmax [tracks/s], since two positive/negative
pulses are outputted per track, the minimum track count pulse width
is represented by 28 minimum track count pulse width = 1 2 V max [
s ] ( Formula 56 )
[0277] and the minimum track count pulse width of the variable
filter means 501 is set according to the above formula.
[0278] Further, setting the minimum track count pulse width is
carried out every time the data (count) for performing detection of
the vibration amount is obtained. When the value of the minimum
track count pulse width varies by a predetermined value or more at
the same rotation speed, there is a high possibility of false track
counting of the previous counts because an optimum track count
filter has not been set, and therefore, the value of the minimum
track count pulse width is discarded, and only the counts after the
change should be adopted as the counts for vibration detection.
[0279] As described above, according to the eighth embodiment, the
counts obtained before the set value of the variable filter means
501 has changed by a predetermined value or more are not used
because the possibility of false counting is high. Therefore, track
counting most suitable for vibration detection can be accurately
carried out at all times.
[0280] (Embodiment 9)
[0281] Hereinafter, an information disc recording/playback
apparatus and a vibration detection method for the information disc
recording/playback apparatus according to a ninth embodiment of the
present invention will be described taking a DVD-ROM player as an
example, with reference to FIG. 7.
[0282] In FIG. 7, the same reference numerals as those shown in
FIG. 1 denote the same or corresponding parts, and reference
numeral 701 denotes a pulse width storage means for holding the
width of a pulse that is just previous to the current pulse.
Reference numeral 702 denotes a filter means which receives the
track cross pulse outputted from the track cross pulse detection
means 112, and outputs it to the count means 115. At this time, the
pulse width is measured, and when the measured pulse width is a
predetermined value smaller than the pulse width stored in the
pulse width storage means 702, this pulse is regarded as one due to
false count and is not outputted.
[0283] As for the amount of change in the pulse width that is not
counted, the measured pulse width should not be counted when it
becomes smaller than the just-previous pulse width by a
predetermined ratio, for example, 0.5.
[0284] As described above, according to the ninth embodiment of the
present invention, the pulse width storage means 701 and the filter
means 702 are provided, and when the filter means 702 judges that
the measured pulse width is a predetermined value smaller than the
just-previous pulse width which is stored in the pulse width
storage means 701, this pulse is regarded as one due to false
detection caused by noise and is not counted by the count means
115. Therefore, track counting most suitable for vibration
detection can be accurately carried out at all times, without
requiring time for excessive measurement.
APPLICABILITY IN INDUSTORY
[0285] An information disc recording/playback apparatus and a
vibration detection method for the information disc
recording/playback apparatus according to the present invention are
valuable as an information disc recording/playback apparatus having
a vibration measurement means for measuring vibrations caused by
eccentricity of a disc, and a vibration detection method for the
information disc recording/playback apparatus, and particularly,
the apparatus and method are valuable as those having a
construction for detecting vibrations using track counting.
* * * * *