U.S. patent application number 09/796829 was filed with the patent office on 2001-07-19 for multiple layer disk reproducing apparatus, and apparatus for reproducing information record medium.
Invention is credited to Kobayashi, Hideki, Takeya, Noriyoshi.
Application Number | 20010008506 09/796829 |
Document ID | / |
Family ID | 26476235 |
Filed Date | 2001-07-19 |
United States Patent
Application |
20010008506 |
Kind Code |
A1 |
Takeya, Noriyoshi ; et
al. |
July 19, 2001 |
Multiple layer disk reproducing apparatus, and apparatus for
reproducing information record medium
Abstract
An apparatus for reproducing a multiple layer disk, which
comprising a plurality of layers each having an information record
surface on which record information is recorded, is provided with:
a read device for reading the record information from each of the
layers; a reproduction process device for applying a predetermined
reproduction process to the record information read by the read
device in accordance with a reproduction process parameter, which
is set therein and which comprises at least one of a gain value and
an equalizer value, to thereby output a reproduction information
signal; a drive device for driving the read device to jump from one
reading state for reading one of the layers to another reading
state for reading another of the layers; a memory for storing a
plurality of reproduction process parameters corresponding to the
layers in advance of reproduction; and a set device for reading out
one of the stored reproduction process parameters, corresponding to
another of the layers as a destination of jumping of the read
device, from the memory and setting the read out reproduction
process parameter in the reproduction process device, in case that
the read device is driven to jump by the drive device.
Inventors: |
Takeya, Noriyoshi;
(Tokorozawa-shi, JP) ; Kobayashi, Hideki;
(Tokorozawa-shi, JP) |
Correspondence
Address: |
PITNEY, HARDIN, KIPP & SZUCH LLP
711 Third Avenue
New York
NY
10017
US
|
Family ID: |
26476235 |
Appl. No.: |
09/796829 |
Filed: |
March 1, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09796829 |
Mar 1, 2001 |
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08855369 |
May 13, 1997 |
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6240054 |
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Current U.S.
Class: |
369/44.29 ;
369/53.29; G9B/19.017; G9B/7.018; G9B/7.093 |
Current CPC
Class: |
G11B 7/08523 20130101;
G11B 7/0945 20130101; G11B 2007/0013 20130101; G11B 19/12 20130101;
G11B 7/0901 20130101; G11B 7/005 20130101; G11B 7/0908
20130101 |
Class at
Publication: |
369/44.29 ;
369/53.29 |
International
Class: |
G11B 007/095 |
Foreign Application Data
Date |
Code |
Application Number |
May 15, 1996 |
JP |
P08-144966 |
Jun 7, 1996 |
JP |
P08-145346 |
Claims
What is claimed is:
1. An apparatus for reproducing a multiple layer disk comprising a
plurality of layers each having an information record surface on
which record information is recorded, said apparatus comprising: a
read device for reading the record information from each of the
layers; a reproduction process device for applying a predetermined
reproduction process to the record information read by said read
device in accordance with a reproduction process parameter, which
is set therein and which comprises at least one of a gain value and
an equalizer value, to thereby output a reproduction information
signal; a drive device for driving said read device to jump from
one reading state for reading one of the layers to another reading
state for reading another of the layers: a memory for storing a
plurality of reproduction process parameters corresponding to the
layers in advance of reproduction; and a set means for reading out
one of the stored reproduction process parameters, corresponding to
said another of the layers as a destination of jumping of said read
device, from said memory and setting the read out reproduction
process parameter in said reproduction process device, in case that
said read device is driven to jump by said drive device.
2. An apparatus according to claim 1, wherein said memory stores
the reproduction process parameters each comprising at least one of
the gain value of a focus servo loop for said reproduction process
device and the gain value of a tracking servo loop for said
reproduction process device.
3. An apparatus for reproducing a multiple layer disk comprising a
plurality of layers each having an information record surface on
which record information is recorded, said apparatus comprising: a
read device having an objective lens for optically reading the
record information from each of the layers through said objective
lens; a reproduction process device for applying a predetermined
reproduction process to the record information read by said read
device in accordance with at least one of again value and an
equalizer value of a focus servo loop, and a gain value and an
equalizer value of another servo loop other than the focus servo
loop, which are set therein, to thereby output a reproduction
information signal and a focus error signal corresponding to the
reproduction information signal; a drive device for driving said
read device to move said objective lens in a focus direction of
said objective lens; a first measurement means for measuring at
least one of the gain value and the equalizer value of the focus
servo loop for each of the layers on the basis of the focus error
signal of each of the layers; a second measurement means for
measuring at least one of the gain value and the equalizer value of
said another servo loop for one of the layers on the basis of a
reflectance factor of said one of the layers; a memory for storing
the measured gain values and equalizer values measured by said
first and second measurement means; a calculation means for
calculating a ratio of at least one of the gain value and the
equalizer value of the focus servo loop for said one of the layers
with respect to those for another of the layers; and a set means
for setting the gain value and the equalizer value of said another
servo loop for said another of the layers on the basis of the ratio
calculated by said calculation means, to said reproduction process
device.
4. An apparatus according to claim 3, wherein said first
measurement means takes in focus error signals of all the layers
from said reproduction process device while said objective lens is
moved up or down just once, to thereby measure at least one of the
gain value and the equalizer value of the focus servo loop for each
of the layers.
5. An apparatus according to claim 1, further comprising a
detection means for detecting a maximum amplitude value of an RF
signal of each of the layers, from the record information read by
said read device, said memory stores at least one of the gain value
and the equalizer value for the RF signal, which are obtained from
the maximum amplitude value detected by said detection means.
6. An apparatus for reproducing a multiple layer disk comprising a
plurality of layers each having an information record surface on
which record information is recorded, said apparatus comprising: a
read device for reading the record information from each of the
layers; a detection means for detecting a maximum amplitude value
of an RF signal of each of the layers, from the record information
read by said read device; a reproduction process device for
applying a predetermined reproduction process to the record
information read by said read device in accordance with a
reproduction process parameter, which is set therein and which
comprises at least one of a gain value and an equalizer value, to
thereby output a reproduction information signal; a memory for
storing a plurality of predetermined reproduction process
parameters in advance of reproduction; and a selection means for
selecting one of the predetermined reproduction process parameters
stored in said memory, on the basis of the maximum amplitude value
detected by said detection means, and setting the selected
reproduction process parameter in said reproduction process
device.
7. An apparatus for reproducing an information record medium
comprising one or a plurality of layers each having an information
record surface on which record information is recorded, said
apparatus comprising: a read device having an objective lens for
optically reading the record information from the information
record surface through said objective lens; a reproduction process
device for applying a predetermined reproduction process to the
record information read by said read device, to thereby generate a
reproduction information signal and a focus error signal
corresponding to the reproduction information signal; a drive
device for driving said read device to move said objective lens in
a focusing direction of said objective lens according to a control
signal; a time counting means for measuring a time interval between
two successive focus error signals generated by said reproduction
process device; an interval calculation means for calculating a
layer interval between the layers on the basis of the time interval
measured by said time counting means if a plurality of focus error
signals are generated, which have signal levels exceeding a
predetermined standard value set in advance, while said objective
lens is moved in either one direction by said drive device; a
selection means for selecting one parameter for the control signal,
which corresponds to the layer interval calculated by said interval
calculation means, among a plurality of parameters for the control
signal, which are set in advance to move said objective lens
between the layers; a parameter memory for storing the parameter
selected by said selection means; and a control means for
generating the control signal based on the parameter stored in said
parameter memory, and thereby controlling said drive device to
drive said read device to move said objective lens.
8. An apparatus according to claim 7, wherein said drive device
drives said read device to move said objective lens when a pulse
signal is applied as the control signal to said drive device, said
parameter for the control signal comprises at least one of a pulse
width, a peak value, a brake time and a gain up time of the pulse
signal.
9. An apparatus according to claim 7, further comprising a
discrimination means for discriminating a type of said information
record medium on the basis of the time interval measured by said
time counting means, as for the focus error signal, which is
generated during a reciprocation motion of said objective lens by
said drive device and which exceeds the predetermined standard
value.
10. An apparatus according to claim 7, wherein said reproduction
process device further generates a tracking error signal
corresponding to the reproduction information signal, and said
apparatus further comprises: a servo calculation means for
calculating at least one of a focus gain value and a tracking gain
value of each of the layers on the basis of at least one of the
focus error signal and the tracking error signal generated by said
reproduction process device; a gain memory for storing at least one
of the focus gain value and the tracking gain value calculated by
said servo calculation means: and a servo control means for
performing at least one of a focus servo control and a tracking
servo control, on the basis of at least one of the focus gain value
and the tracking gain value stored in said gain memory.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention is related with an apparatus for
reproducing information of an information record medium such as an
optical disk, on which the information is recorded magnetically or
by means of a phase pit and the like, and in which an information
record layer is formed in multiple layers or a one-layer. The
present invention is also related with an apparatus for
automatically setting, in the reproducing apparatus for reproducing
the multiple-layer disk, each loop gain value and/or equalizer
value in a focus servo and a tracking servo, and a level value
and/or an equalizer value in an RF (Radio Frequency) signal, which
are optimal for each layer.
[0003] 2. Description of the Related Art
[0004] Recently, DVD (Digital Video or Versatile Disk) has been
remarkably developed which dramatically improves a memory density
over a conventional CD and services as a high density record medium
that can record one movie and the like.
[0005] Although this DVD has a different disk substrate thickness
from the CD, the principle of reading a record pit responsible for
storing information is similar to that of the CD. Thus, a CD/DVD
compatible type of a reproducing apparatus may be proposed. In this
CD/DVD compatible type of the reproducing apparatus, in order to
optimally collect an information recording beam on an information
record surface of each disk, it is considered to employ a bifocal
lens that can emit two light beams focused on different positions
on one straight line, or a method of exchanging lenses so as to
change a focal length in corresponding with the type of the disk,
or other methods.
[0006] Incidentally, in the DVD, it is prescribed that a linear
velocity thereof is higher than that of the CD from a request of
making a density higher. So, it is necessary that servo gains and
servo frequency bands in focus and tracking servo circuits are made
different between the CD and the DVD. More actually, the DVD is set
to be wider in servo band on a high frequency side than the CD. The
DVD is set to be larger in servo gain than the CD.
[0007] Therefore, in order to share the servo circuit between the
CD and the DVD in the CD/DVD compatible type of the reproducing
apparatus, it is necessary to adjust the servo gain and the servo
band based on the disk. Namely, prior to a reproduction operation,
it is judged whether or not an optical disk to be reproduced is the
CD or the DVD. The servo gain and the servo band for the disk are
correctly adjusted on the basis of a signal indicative of a
reflectance factor of the optical disk based on the judged result,
for example, the S-shaped signal of the focus error, an RF signal
or the like. The once adjusted value is maintained until the disk
is exchanged.
[0008] There are a single layer disk, where an information record
surface on which a pit responsible for recording the information is
recorded is composed of a single layer, and a multiple-layer disk
having a plurality of record layers (for example, two layers)
within a same thickness portion, in the DVD. In a case of the
multiple-layer disk, there is, for example, such a problem that if
a gain set for a record layer of a first layer in a two-layer disk
is used for a record layer in a second layer as it is, the
optimization is not performed at the record layer in the second
layer, because of a relative slope between the respective record
layers, different reflectance factors of the respective record
layers, and other reasons. To solve this problem, it is enough to
perform a setting operation of the gain on the basis of the focus
error signal and the like so as to set to a gain corresponding to
the record layer at the jump destination, each time the reading
beam is jumped from the record layer in the first layer to the
record layer in the second layer during reproducing or from the
record layer in the second layer to the record layer in the first
layer. However, in this case, initial setting for the gain and the
band should be carried out each time the jump operation between the
layers is performed. This results in a problem that the jump
operation takes a long time to complete. Therefore, in a case of
recording a series of related information, such as movies or the
like, over two layers, the jump operation between the layers causes
a continuous reproduction to be interrupted.
[0009] In this manner, there is a first problem in the above
mentioned reproducing apparatus.
[0010] On the other hand, to reproduce the DVD, an apparatus is
used which comprises an optical pickup for collecting light beams
on a focus position of an information record layer of the DVD and
keeps a distance between an object lens of the optical pickup and
the information record layer constant by using a focus servo
control, to stably read the information.
[0011] Here since an area in which a servo error signal can be
detected is narrow in this focus servo control, a so-called focus
search operation is required. In this focus search operation, prior
to performing the focus servo control, a servo loop is made open,
the objective lens is moved by a predetermined amount in a
direction vertical to the information record layer, and a zero
cross of a focus error signal (S-shaped signal) outputted at that
time is checked, and thereby the servo loop is made close.
[0012] However, in case of the DVD of the multiple-layer disk type,
since the information record layer is composed of multiple layers
so as to record much information, it is required to perform the
focus search operation for each layer, to reproduce such a
multiple-layer disk from one side thereof.
[0013] That is, in a case of the multiple-layer disk type of the
reproducing apparatus, it is necessary to jump the objective lens
of the optical pickup to an appropriate position, each time the
information record layer to be reproduced is switched. However,
since intervals between the respective information record layers
are different from each other in the respective disks within a disk
standard, it is not possible to unconditionally set the jump
amount. Thus, a standard position for the focus servo must be set
by performing the focus search operation for each disk and each
layer.
[0014] Therefore, in a case of the conventional apparatus for
performing the focus search operation, it is necessary to detect
the zero cross of the focus error signal each time the information
record layers are switched. As a result, it is difficult to quickly
switch between the information record layers in the multiple-layer
DVD.
[0015] In this manner, there is a second problem in the above
mentioned reproducing apparatus.
SUMMARY OF THE INVENTION
[0016] It is therefore a first object of the present invention,
from the viewpoint of the above mentioned first problem, to provide
a multiple-layer disk reproducing apparatus, which can quickly
perform a stable servo control, even if the reading beam is jumped
between the layers, at a time of reproducing the record information
from the multiple-layer disk.
[0017] It is therefore a second object of the present invention,
from the viewpoint of the above mentioned second problem, to
provided an apparatus for reproducing the DVD or the like, which
can perform a quick reproducing operation at a time of switching
the record layers of the DVD or the like, in which the information
record layers may be formed in multiple layers.
[0018] The above mentioned first object of the present invention
can be achieved by a first apparatus for reproducing a multiple
layer disk comprising a plurality of layers each having an
information record surface on which record information is recorded.
The first apparatus is provided with: a read device for reading the
record information from each of the layers; a reproduction process
device for applying a predetermined reproduction process to the
record information read by the read device in accordance with a
reproduction process parameter, which is set therein and which
comprises at least one of a gain value and an equalizer value, to
thereby output a reproduction information signal; a drive device
for driving the read device to jump from one reading state for
reading one of the layers to another reading state for reading
another of the layers; a memory for storing a plurality of
reproduction process parameters corresponding to the layers in
advance of reproduction; and a set device for reading out one of
the stored reproduction process parameters, corresponding to
another of the layers as a destination of jumping of the read
device, from the memory and setting the read out reproduction
process parameter in the reproduction process device, in case that
the read device is driven to jump by the drive device.
[0019] According to the first apparatus of the present invention, a
plurality of reproduction process parameters corresponding to the
layers are stored in the memory in advance of reproduction. In
reproduction, the record information is read from each of the
layers, by the read device such as an optical pickup. Then, a
predetermined reproduction process is applied to the record
information in accordance with a reproduction process parameter,
which is set therein and which comprises at least one of a gain
value and an equalizer value, by the reproduction process device,
such as an RF amplifier, a low pass filter, an A/D converter, a
focus gain controller, a digital equalizer and the like. Thus, the
reproduction information signal is outputted from the reproduction
process device. In case that the read device is driven by the drive
device to jump from one reading state for reading one of the layers
to another reading state for reading another of the layers, one of
the stored reproduction process parameters, corresponding to this
another of the layers as a destination of jumping of the read
device, is read out from the memory, by the set device. Further,
this read out reproduction process parameter is set in the
reproduction process device, by the set device. Accordingly, after
jumping, the predetermined reproduction process is applied to the
record information appropriately in accordance with the
reproduction process parameter, which readily corresponds to the
layer at the jump destination. Therefore, it is not necessary to
measure or determine the gain value and/or the equalizer value for
the layer at the jump destination each time the jump is performed.
Thus, a stable and quick servo control can be performed, even if
the jumping operation between the layers is performed, according to
the first apparatus of the present invention.
[0020] In one aspect of the first apparatus of the present
invention, the memory stores the reproduction process parameters
each comprising at least one of the gain value of a focus servo
loop for the reproduction process device and the gain value of a
tracking servo loop for the reproduction process device.
[0021] According to this aspect, since the gain value of the focus
servo loop and/or the gain value of the tracking servo loop are
stored in the memory, the stability of each servo loop in
reproduction can be improved, so that the servo control operation
can be quickly and stably performed.
[0022] The above mentioned first object of the present invention
can be also achieved by a second apparatus for reproducing a
multiple layer disk comprising a plurality of layers each having an
information record surface on which record information is recorded.
The second apparatus is provided with: a read device having an
objective lens for optically reading the record information from
each of the layers through the objective lens; a reproduction
process device for applying a predetermined reproduction process to
the record information read by the read device in accordance with
at least one of a gain value and an equalizer value of a focus
servo loop, and a gain value and an equalizer value of another
servo loop other than the focus servo loop, which are set therein,
to thereby output a reproduction information signal and a focus
error signal corresponding to the reproduction information signal;
a drive device for driving the read device to move the objective
lens in a focus direction of the objective lens; a first
measurement device for measuring at least one of the gain value and
the equalizer value of the focus servo loop for each of the layers
on the basis of the focus error signal of each of the layers; a
second measurement device for measuring at least one of the gain
value and the equalizer value of another servo loop for one of the
layers on the basis of a reflectance factor of one of the layers; a
memory for storing the measured gain values and equalizer values
measured by the first and second measurement devices; a calculation
device for calculating a ratio of at least one of the gain value
and the equalizer value of the focus servo loop for one of the
layers with respect to those for another of the layers; and a set
device for setting the gain value and the equalizer value of
another servo loop for another of the layers on the basis of the
ratio calculated by the calculation device, to the reproduction
process device.
[0023] According to the second apparatus of the present invention,
in reproduction, the record information is optically read from each
of the layers through the objective lens, by the read device. Then,
a predetermined reproduction process is applied to this record
information in accordance with at least one of a gain value and an
equalizer value of a focus servo loop, and a gain value and an
equalizer value of another servo loop other than the focus servo
loop (e.g., a tracking servo loop, a spindle servo loop), which are
set therein, by the reproduction process device. Thus, a
reproduction information signal and a focus error signal
corresponding to the reproduction information signal are outputted
by the reproduction process device. In case that the read device is
driven to move the objective lens in a focus direction of the
objective lens between the layers, by the drive device, at least
one of the gain value and the equalizer value of the focus servo
loop for each of the layers is measured on the basis of the focus
error signal of each of the layers, by the first measurement
device. Further, at least one of the gain value and the equalizer
value of another servo loop (e.g., a tracking servo loop, a spindle
servo loop) for one of the layers is measured on the basis of a
reflectance factor of this one of the layers, by the second
measurement device. Then, these measured gain values and equalizer
values are stored in the memory. Then, a ratio of the gain value
and/or the equalizer value of the focus servo loop for this one of
the layers with respect to those for another of the layers is
calculated by the calculation device. Finally, the gain value and
the equalizer value of another servo loop (e.g. a tracking servo
loop, a spindle servo loop) for another of the layers is set on the
basis of the calculated ratio to the reproduction process device,
by the set device. Accordingly, before or after moving the
objective lens in the focus direction, the predetermined
reproduction process is applied to the record information
appropriately in accordance with the gain value and/or the
equalizer value, which readily corresponds to the layer before or
after the movement of the objective lens. Since the gain value
and/or the equalizer value of the servo loop for the layer or
layers other than one layer is obtained by use of the ratio, the
stability of each servo loop in reproduction can be improved while
the servo control operation can be more stably and quickly
performed, according to the second apparatus of the present
invention.
[0024] In one aspect of the second apparatus of the present
invention, the first measurement device takes in focus error
signals of all the layers from the reproduction process device
while the objective lens is moved up or down just once, to thereby
measure at least one of the gain value and the equalizer value of
the focus servo loop for each of the layers.
[0025] According to this aspect, the focus error signals of all the
layers are taken in while the objective lens is moved up or down
just once. Thus, the servo control operation can be even more
stably and quickly performed.
[0026] On the other hand, in another aspect of the first apparatus
of the present invention, the first apparatus is further provided
with a detection device for detecting a maximum amplitude value of
an RF signal of each of the layers, from the record information
read by the read device. The memory stores at least one of the gain
value and the equalizer value for the RF signal, which are obtained
from the maximum amplitude value detected by the detection
device.
[0027] According to this aspect, a maximum amplitude value of an RF
signal of each of the layers, is detected from the record
information read, by the detection device. Then, at least one of
the gain value and the equalizer value for the RF signal, which are
obtained from the maximum amplitude value detected by the detection
device, are stored in the memory. Therefore, it is possible to
reproduce the RF signal accurately in reproduction.
[0028] The above mentioned first object of the present invention
can be also achieved by a third apparatus for reproducing a
multiple layer disk comprising a plurality of layers each having an
information record surface on which record information is recorded.
The third apparatus is provided with: a read device for reading the
record information from each of the layers; a detection device for
detecting a maximum amplitude value of an RF signal of each of the
layers, from the record information read by the read device; a
reproduction process device for applying a predetermined
reproduction process to the record information read by the read
device in accordance with a reproduction process parameter, which
is set therein and which comprises at least one of a gain value and
an equalizer value, to thereby output a reproduction information
signal; a memory for storing a plurality of predetermined
reproduction process parameters in advance of reproduction; and a
selection device for selecting one of the predetermined
reproduction process parameters stored in the memory, on the basis
of the maximum amplitude value detected by the detection device,
and setting the selected reproduction process parameter in the
reproduction process device.
[0029] According to the third apparatus of the present invention, a
plurality of predetermined reproduction process parameters are
stored in the memory in advance of reproduction. In reproduction,
the record information is read from each of the layers, by the read
device. Then, a maximum amplitude value of an RF signal of each of
the layers is detected from the record information read, by the
detection device. Then, a predetermined reproduction process is
applied to this record information in accordance with a
reproduction process parameter, which is set therein and which
comprises at least one of a gain value and an equalizer value, by
the reproduction process device. Thus, a reproduction information
signal is outputted by the reproduction process device. At this
time, if the layer to be reproduced is changed, one of the
predetermined reproduction process parameters stored in the memory
is selected on the basis of the detected maximum amplitude value,
by the selection device. And that, the selected reproduction
process parameter is set in the reproduction process device.
Therefore, since the gain value and/or the equalizer value can be
selected from the memory in accordance with the maximum amplitude
value, the servo control operation for the RF signal can be
reproduced quickly by use of the gain value and/or the equalizer
value, which readily corresponds to the pertinent layer without the
necessity of measuring and/or calculating the gain value and/or the
equalizer value of the RF signal for the pertinent layer, according
to the third apparatus of the present invention.
[0030] The above mentioned second object of the present invention
can be achieved by a fourth apparatus for reproducing an
information record medium comprising one or a plurality of layers
each having an information record surface on which record
information is recorded. The fourth apparatus is provided with: a
read device having an objective lens for optically reading the
record information from the information record surface through the
objective lens; a reproduction process device for applying a
predetermined reproduction process to the record information read
by the read device, to thereby generate a reproduction information
signal and a focus error signal corresponding to the reproduction
information signal; a drive device for driving the read device to
move the objective lens in a focusing direction of the objective
lens according to a control signal; a time counting device for
measuring a time interval between two successive focus error
signals generated by the reproduction process device; an interval
calculation device for calculating a layer interval between the
layers on the basis of the time interval measured by the time
counting device if a plurality of focus error signals are
generated, which have signal levels exceeding a predetermined
standard value set in advance, while the objective lens is moved in
either one direction by the drive device; a selection device for
selecting one parameter for the control signal, which corresponds
to the layer interval calculated by the interval calculation
device, among a plurality of parameters for the control signal,
which are set in advance to move the objective lens between the
layers; a parameter memory for storing the parameter selected by
the selection device; and a control device for generating the
control signal based on the parameter stored in the parameter
memory, and thereby controlling the drive device to drive the read
device to move the objective lens.
[0031] According to the fourth apparatus of the present invention,
in reproduction, the record information is read from the
information record surface through the objective lens, by the read
device. Then, a predetermined reproduction process is applied to
this record information, by the reproduction process device. Thus,
a reproduction information signal and a focus error signal
corresponding to the reproduction information signal are generated
by the reproduction process device. In the operation of the fourth
apparatus especially, a time interval between two successive focus
error signals generated by the reproduction process device is
measured by the time counting device. In this condition, if the
read device is driven by the drive device to move the objective
lens in the focusing direction according to the control signal
i.e., if the objective lens is moved toward or away from the
information record medium, the focal point of the objective lens
passes through the information record surface of the layer or
layers of the information record medium. Thus, the focus error
signal is generated in correspondence with the passed information
record surface. While the objective lens is moved in either one
direction by the drive device in this manner, if a plurality of
focus error signals are generated, which have signal levels
exceeding a predetermined standard value set in advance, the layer
interval (i.e. a distance between the information record surfaces
of two adjacent layers) is calculated on the basis of the time
interval measured by the time counting device, by the interval
calculation device. Namely, such a fact that a plurality of focus
error signals, which have signal levels exceeding the predetermined
standard value, are generated during the movement of the objective
lens in one direction in this way, indicates that the pertinent
information record medium is a multiple layer type. Thus, the layer
interval of the information record medium can be obtained by the
relationship between the moving speed of the objective lens, which
is a predetermined value, and the measured time interval. After the
layer interval is calculated in this manner, one parameter for the
control signal, which corresponds to the calculated layer interval,
is selected among a plurality of parameters for the control signal,
which are set in advance to move the objective lens between the
layers, by the selection device. Then, this selected parameter is
stored in the parameter memory. After that, the control signal is
generated on the basis of the parameter stored in the parameter
memory, by the control device, and that the drive device is
controlled according to this generated control signal. Therefore,
as long as a reproduction operation is performed with respect to
any desirable layer of the pertinent information record medium, by
outputting the control signal based on the stored parameter in the
parameter memory, the objective lens can be moved to an appropriate
position with respect to this desirable layer.
[0032] In this manner, it is possible to move the objective lens
quickly and accurately so as to position its focal point on the
information record surface of any desirable layer of the
information record medium even if the information record medium
comprises one layer or a plurality of layers, so that the
reproduction of such an information record medium can be smoothly
performed.
[0033] In one aspect of the fourth apparatus of the present
invention, the drive device drives the read device to move the
objective lens when a pulse signal is applied as the control signal
to the drive device. The parameter for the control signal comprises
at least one of a pulse width, a peak value, a brake time and a
gain up time of the pulse signal.
[0034] According to this aspect, the objective lens is moved when
the pulse signal is applied to the drive device. At this time, the
moving distance and the stability of the movement of the objective
lens depends upon the pulse width, the peak value, the brake time
and the gain up time of the pulse signal. Therefore, by storing at
least one of these parameters and by outputting the control signal
based on these stored parameters to the drive device, it is
possible to move the objective lens by a desirable moving distance
i.e., to move the objective lens quickly and accurately so as to
position its focal point on the information record surface of any
desirable layer of the pertinent information record medium, so that
the reproduction of such an information record medium can be
smoothly performed.
[0035] In another aspect of the fourth apparatus of the present
invention, the fourth apparatus is further provided with a
discrimination device for discriminating a type of the information
record medium on the basis of the time interval measured by the
time counting device, as for the focus error signal, which is
generated during a reciprocation motion of the objective lens by
the drive device and which exceeds the predetermined standard
value.
[0036] According to this aspect, if the objective lens is moved
toward the information record medium, for example, the time
interval from the time point of staring the movement until the
focus error signal exceeding the standard value is generated,
becomes shorter as the distance from the surface of the information
record medium to the information record surface corresponding to
the focus error signal becomes shorter, and becomes longer as this
distance becomes longer. Further, in case of the information record
medium of the multiple layer type, a plurality of successive focus
error signals are generated. On the other hand, after the objective
lens arrives at its upper limit position, if the objective lens is
nextly moved away from the information record medium, for example,
the time interval from a time point of starting this movement until
the focus error signal firstly exceeding the standard level becomes
shorter as the distance from the surface to the information record
surface of the information record medium becomes longer, and
becomes longer as this distance becomes shorter. Further, in case
of the information record medium of the multiple layer type, a
plurality of successive focus error signals are generated.
Therefore, if the objective lens is moved in this way, the time
interval between two successive focus error signals becomes shorter
as the distance from the surface to the information record surface
becomes longer, becomes longer as this distance becomes shorter,
and becomes the shortest in case of the multiple layer type. On the
other hand, if the moving order of the objective lens is inverted,
an inverse relationship between the time interval and the distance
of the above is obtained. In this manner, the type of the
information record medium is discriminated by the discrimination
device on the basis of the time interval measured by the time
counting device, as for the focus error signal, which is generated
during a reciprocation motion of the objective lens and which
exceeds the predetermined standard value. Furthermore, if the type
of the information record medium is discriminated as the multiple
layer type, the calculation of the layer interval as well as the
selection and storage of the parameter for the control signal based
on the calculation result are performed.
[0037] Consequently, the movement of the objective lens for the
desirable layer of the information record medium can be quickly and
accurately performed, and, even in case of the information record
medium of the multiple layer type, the reproduction can be smoothly
performed. In correspondence with the type of the information
record medium, the focus servo control can be performed
accurately.
[0038] In another aspect of the fourth apparatus of the present
invention, the reproduction process device further generates a
tracking error signal corresponding to the reproduction information
signal. And that, the fourth apparatus is further provided with: a
servo calculation device for calculating at least one of a focus
gain value and a tracking gain value of each of the layers on the
basis of at least one of the focus error signal and the tracking
error signal generated by the reproduction process device; a gain
memory for storing at least one of the focus gain value and the
tracking gain value calculated by the servo calculation device; and
a servo control device for performing at least one of a focus servo
control and a tracking servo control, on the basis of at least one
of the focus gain value and the tracking gain value stored in the
gain memory.
[0039] According to this aspect, in reproduction, a tracking error
signal is further generated by the reproduction process device.
Then, at least one of a focus gain value and a tracking gain value
of each of the layers is calculated by the servo calculation device
on the basis of at least one of the focus error signal and the
tracking error signal. For example, the peak to peak values of the
focus error signals are taken in and the average of these values is
calculated, so that the focus gain value is calculated and stored
into the gain memory, while the peak to peak values of the tracking
error signals are taken in and the average of these values is
calculated, so that the tracking gain value is calculated and
stored into the gain memory. In this operation, at the time of
taking in the focus error signals, the calculation of the layer
interval as well as the selection and storage of the parameter for
the control signal is performed. Therefore, in case of reproducing
the information record medium of the multiple layer type, the
movement of the objective lens for the desirable layer can be
performed on the basis of the parameter stored in the parameter
memory, and the focus servo control and/or the tracking servo
control can be Performed on the basis of the focus gain value
and/or the tracking gain value stored in the gain memory.
[0040] Consequently, the reproduction of the information record
medium, which may be the single layer type or the multiple layer
type, can be performed even more smoothly.
[0041] The nature, utility, and further features of this invention
will be more clearly apparent from the following detailed
description with respect to preferred embodiments of the invention
when read in conjunction with the accompanying drawings briefly
described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] FIG. 1 is a block diagram of a multiple layer disk
reproducing apparatus as a first embodiment of the present
invention;
[0043] FIG. 1A is one diagram showing a wave form of a focus error
generated by an optical pickup of bifocal lens type in a CD/DVD
compatible reproducing apparatus for use in the embodiment;
[0044] FIG. 1B is another diagram showing the wave form of the
focus error generated by the optical pickup of bifocal lens type in
the CD/DVD compatible reproducing apparatus for use in the
embodiment;
[0045] FIG. 2A is a cross-sectional view of a DVD of a multiple
layer disk type to be reproduced in the first embodiment;
[0046] FIG. 2B is a diagram showing a relationship between a
structure of a bifocal lens and a focus error signal in the
embodiment;
[0047] FIG. 3A is one time chart of a generation of a focus error
signal of a first layer in the first embodiment;
[0048] FIG. 3B is another time chart of the generation of the focus
error signal of the first layer in the first embodiment;
[0049] FIG. 3C is another time chart of the generation of the focus
error signal of the first layer in the first embodiment;
[0050] FIG. 4A is one time chart of a gene ration of a focus error
signal of a second layer in the first embodiment;
[0051] FIG. 4B is another time chart of the generation of the focus
error signal of the second layer in the first embodiment;
[0052] FIG. 4C is another time chart of the generation of the focus
error signal of the second layer in the first embodiment;
[0053] FIG. 5 is one flow chart showing an operation of the first
embodiment;
[0054] FIG. 6 is another flow chart, continued from FIG. 5, showing
the operation of the first embodiment;
[0055] FIG. 7A is one time chart of a generation of a focus error
signal in a second embodiment of the present invention;
[0056] FIG. 7B is another time chart of the generation of the focus
error signal in the second embodiment;
[0057] FIG. 7C is another time chart of the generation of the focus
error signal in the second embodiment;
[0058] FIG. 8 is one flow chart showing an operation of the second
embodiment;
[0059] FIG. 9 is another flow chart, continued from FIG. 8, showing
the operation of the second embodiment;
[0060] FIG. 10 is a flow chart showing an operation of a third
embodiment of the present invention;
[0061] FIG. 11 is a flow chart showing an operation of a method of
discriminating the disk in lens exchanging type for use in the
embodiments;
[0062] FIG. 12 is a flow chart showing an operation of a method of
discriminating the disk in bifocal lens type for use in the
embodiments;
[0063] FIG. 13 is a flow chart showing an operation of a fourth
embodiment of the present invention;
[0064] FIG. 14 is a flow chart showing an operation of a fifth
embodiment of the present invention;
[0065] FIG. 15 is a flow chart showing an operation of a sixth
embodiment of the present invention;
[0066] FIG. 16 is a block diagram showing a summarized construction
of a reproducing apparatus for an information record medium as a
seventh embodiment of the present invention;
[0067] FIG. 17 is a timing chart showing one example of control
signals etc. with respect to a focus driver in the seventh
embodiment;
[0068] FIG. 18 is a timing chart showing another example of control
signals etc. with respect to the focus driver in the seventh
embodiment;
[0069] FIG. 19 is a timing chart showing a moving condition of an
objective lens of an optical pickup, a focus error signal obtained
thereat and a start and stop operation of a timer in the seventh
embodiment;
[0070] FIG. 20A is a timing chart showing one example of a
time-measurement timing for intervals of the focus error signals in
the seventh embodiment;
[0071] FIG. 20B is a timing chart showing another example of a
time-measurement timing for intervals of the focus error signals in
the seventh embodiment;
[0072] FIG. 21 is a flow chart showing an operation of controlling
a layer interval measurement in the seventh embodiment;
[0073] FIG. 22 is a flow chart showing an operation of controlling
a layer interval measurement in an eighth embodiment of the present
invention;
[0074] FIG. 23 is a timing chart showing a moving condition of an
objective lens of an optical pickup, a focus error signal obtained
thereat and a start and stop operation of a timer in the eighth
embodiment;
[0075] FIG. 24 is a block diagram showing a summarized construction
of a reproducing apparatus for an information record medium as a
ninth embodiment of the present invention;
[0076] FIG. 25 is one flow chart showing an operation of
controlling a layer interval measurement in the ninth
embodiment;
[0077] FIG. 26 is another flowchart, continued from FIG. 25,
showing the operation of controlling the layer interval measurement
in the ninth embodiment;
[0078] FIG. 27 is a flowchart showing an operation of
discriminating a disk in the ninth embodiment;
[0079] FIG. 28A is a timing chart showing a moving condition of an
objective lens of an optical pickup a focus error signal obtained
thereat and a start and stop operation of a timer in the ninth
embodiment;
[0080] FIG. 28B is one timing chart of balance control and tracking
gain control operations in the ninth embodiment; and
[0081] FIG. 28C is another timing chart of balance control and
tracking gain control operations in the ninth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0082] [I] Construction of Reproducing Apparatus
[0083] FIG. 1 shows a block diagram of a multiple-layer disk
reproducing apparatus of an embodiment according to the present
invention. An optical disk 20 to be reproduced is rotated at a
defined rotation number by a spindle motor 21. An optical pickup 22
employing a bifocal lens reads out information, by means of a light
beam, from a pit formed on an information record surface of the
optical disk 20. An output signal from the optical pickup 22 is
inputted to an RF Amp 23, and is outputted as an analog signal,
such as a focus error signal, a tracking error signal or the like.
A focus error signal outputted by the RF Amp 23 is sent to a
variable amplifier 25, after unnecessary frequency components are
removed through an LPF (Low Pass Filter) 24. A gain of this
variable amplifier 25 is set by a command from an FGA (Focus GAin
controller) 27 described later. An output signal from the variable
amplifier 25 is converted from an analog signal into a digital
signal by an A/D converter 26, and is then sent to the FGA 27.
[0084] An output from the FGA 27 is weighted into particular
frequency ranges by a D.multidot.EQ (Digital Equalizer) 28, is
pulse-width-converted by a PWM (Pulse Width Modulator) 29, and is
then supplied to a focus coil (not shown) of the optical pickup 22
by a focus coil drive circuit 30. This PWM 29 is a circuit of
sending a signal to the focus coil drive circuit 30. However, a
command from a servo controller 38 described later can prevent the
PWM 29 from sending the signal to the focus coil drive circuit 30.
Thus, the PWM 29 also has a role as a focus loop switch used to
make a focus loop in an open path state or a close path state.
[0085] On the other hand, the tracking error signal outputted by
the RF Amp 23 is supplied to a variable amplifier 32, after
unnecessary frequency components are removed through an LPF 31. An
output signal from the variable amplifier 32 is converted from an
analog signal into a digital signal by an A/D converter 33, and
then supplied to a TGA (Tracking GAin controller) 34. An output
from the TGA 34 is weighted into particular frequency ranges by a
D.multidot.EQ 35, is pulse-width-converted by a PWM 36, and is then
supplied to a tracking coil (not shown) of the optical pickup 22 by
a tracking drive circuit 37. There is also the servo controller 38
for giving commands to the respective circuits on the basis of data
obtained by the FGA 27, the TGA 34, the respective D EQs 28 and 35,
and the like. Calculation of the data is performed, and the command
is given, as the occasion demands, by the servo controller 38. A
ROM 39 and a CPU 40, in which respective defined values required by
the multiple-layer disk type of the reproducing apparatus are
stored, are connected to the servo controller 38.
[0086] An operation section 41 and a RAM 42 are connected to this
CPU 40. Various information detected at an initial operation in the
multiple-layer disk type of the reproducing apparatus is stored in
the CPU 40, and read therefrom as the occasion demands. A
TR.multidot.BL (Tracking BaLance control circuit) 43 is connected
to the servo controller 38. After a control signal of a tracking
balance is converted from a digital signal into an analog signal by
a D/A converter 44, a signal is supplied to the RF Amp 23, and the
optimal tracking balance is accordingly performed. On the other
hand, the RF signal obtained by the RF Amp 23 is supplied through
an amplifier 45 to an EFM (Eight to Fourteen Modulation) decoder
46. The spindle motor 21 is driven by a spindle motor drive circuit
47, and thereby the optical disk 20 is rotated at the defined
rotation speed.
[0087] An RF gain that is optimal for each of the layers in the
multiple-layer disk is supplied through an A/D converter 49 to an
RGA (RF GAin control circuit) 48, by the command from the servo
controller 38. Moreover, the amplifier 45 is controlled by the RGA
48 based on the control signal from the servo controller 38. The
optimal data is supplied to the EFM decoder 46. Accordingly, the
rotation speed of the spindle motor 21 is monitored and
controlled.
[0088] One example of a bifocal lens employed by the optical pickup
22 is explained here in detail with reference to FIGS. 1A and
1B.
[0089] As shown in FIG. 1A, a bifocal lens 12 has a configuration
in which a diffraction grating 13 and an objective lens 11 are
arranged on one optical path. Light beams made parallel to each
other by a collimator lens 14 are divided into three beams: a 0
order light and .+-.1 order lights, by the diffraction grating 13
(the -1 order light is not shown). Utilization of a difference
between the optical path lengths of the 0 order light and the +1
order light among them enables the 0 order light and the +1 order
light to be focused on different positions on an one straight
line.
[0090] Actually, for the information record surface of the DVD or
the CD, the +1 order light is adapted to be focused on a farther
position from the objective lens 11 than the 0 order light. Thus,
the 0 order light is set so as to be optimally collected on the
information record surface of the DVD, and the +1 order light is
set to be optimally collected on the information record surface of
the CD. In a case of considering that an optical pickup using this
bifocal lens is gradually made close to an optical disk, the beam
of the +1 order light is firstly emitted to the information record
surface of the optical disk. Then, an S-shaped signal servicing as
a focus error signal is outputted from a four-division photo diode
built in the optical pickup (not shown) of the disk reproducing
apparatus. Next, an S-shaped signal is obtained which services as a
pseudo focus error signal generated when a reflection light from
the optical disk of the +1 order light returns through the optical
path of the 0 order light. Finally, an S-shaped signal is obtained
which services as a focus error signal corresponding to the 0 order
light.
[0091] FIG. 1B shows the manner in which the S shapes of the 0
order light, the pseudo light and the +1 order light are generated
as mentioned above in a case that the bifocal lens is made close to
the optical disk.
[0092] A light division ratio of the 0 order light to the +1 order
light at the diffraction grating 13 is set to be substantially
equal to each other. Since the optimal collection of the 0 order
light is performed for the DVD and the optimal collection of the +1
order light is performed for the CD, the optimally collected
situation cannot be kept for the reverse combination thereof, for
example, because of generation of spherical aberration and the
like. Thus, in a case that the optical disk is the CD, the S-shaped
signal of the focus error signal corresponding to the +1 order
light has the highest level (FE1), and the S-shaped signal of the
focus error signal corresponding to the 0 order light has the
lowest level. In contrast with this condition, in a case that the
optical disk is the DVD, the S-shaped signal of the focus error
signal corresponding to the 0 order light has the highest level
(FE2), and the S-shaped signal of the focus error signal
corresponding to the +1 order light has the lowest level.
[0093] [II] Explanation of One-Sided Two-Layer Disk
[0094] In a case of an optical disk for DVD shown in FIG. 2A, two
transparent optical disk substrates are bonded together. Each of
the substrates has a diameter of, for example, 120 mm and a
thickness of, for example, 0.6 mm. A protective layer of a first
optical disk (A surface) and a protective layer of a second optical
disk (B surface), which are opposite to each other, are bonded
together with adhesive, and thereby constitute the optical disk
substrate having a thickness of 1.2 mm.
[0095] A pit for recording information on a surface of a
transparent substrate 9 made of synthetic resin of polymethylene
methacrylate and polycarbonate is concentrically or spirally formed
on the A surface. A reflection layer I as a first translucent
layer, in which a display pattern, such as a character, a symbol, a
picture or the like, is constituted by a metallic thin film made of
aluminum having silver-white color or the like, is formed on some
surface of the transparent substrate 9 on which this pit is
formed.
[0096] Moreover, a reflection layer 2 as a second layer composed of
a metallic thin film having golden color made of gold and the like
is formed on a top surface of the reflection layer 1 as the first
layer and a top surface of the transparent substrate 9 on which the
reflection layer 1 as the first layer is not formed. A surface
where the reflection layer 1 as the first layer and the reflection
layer 2 as the second layer are in contact with the pit has
substantially same reflectance factors. A protective layer 3 made
of ultraviolet curing resin is formed on a top surface of the
reflection layer 2 as the second layer. That is, the A surface disk
servicing as a first optical disk is an optical disk having the
two-layer structure composed of the transparent substrate 9, the
pit, the reflection layer 1 as the first layer, the reflection
layer 2 as the second layer, the protective layer 3 and the like.
Similarly to the A surface disk, a pit for recording information on
a surface of a transparent substrate 8 is formed on a second
optical disk (B surface), and a protective layer 5 is formed on top
surfaces of a reflection layer 7 as the first layer and a
reflection layer 6 as the second layer. As mentioned above, the
optical disk substrate having the thickness of 1.2 mm is
constituted by making the protective layers 3 and 5 of these two
optical disk substrates opposite to each other and bonding together
with a hot melt type adhesive 4.
[0097] When reproducing the multiple-layer disk substrate having
the above mentioned multiple-layer structure from one side thereof,
if reproducing by using a bifocal lens, S-shapes with respect to
the first layer and the second layer are continuously generated for
each of the 0 order light, the pseudo light and the +1 order light
as shown in FIG. 2B, in a focus error signal generated when the
lens is moved up and down, since an interval between the first
layer and the second layer is narrow (approximately 40 .mu.m).
[0098] [III] First Embodiment of the Invention
[0099] In a first embodiment of the present invention, a focus
error signal is extracted, which is generated from the first layer,
among focus error signals generated by applying an UP or DOWN
operation to the objective lens while emitting light beams to the
one-sided two-layer disk loaded on a disk loading surface of the
reproducing apparatus. A gain value is set for a focus servo on the
basis of this focus error signal. After that, a balance adjustment
and a gain value setting are performed for a tracking servo on the
basis of a tracking error signal. Next, a focus jump is performed
to a second layer, and the operation similar to that of the above
mentioned case is performed for the second layer. The above
mentioned operation is performed as a setup (initial setting)
operation prior to an actual reproduction operation.
[0100] An operation of the first embodiment according to the
present invention is explained with reference to operation time
charts in FIGS. 3 and 4 and flow charts of FIGS. 5 and 6. At first,
FIG. 3A shows two focus error signals (hereafter, referred to as
FE) detected by the optical pickup 22 when the lens is moved up and
down (in a case of two layers). FIGS. 3A to 3C show only an S shape
of the FE original to the disk, among the +1 order light, the
pseudo light and the 0 order light. That is, only the S shape of
the FE generated by the 0 order light is shown in this embodiment.
In FIG. 3A, a symbol N indicates a number at which the lens is
moved up and down. As shown in FIG. 3B, T1 is a time required from
a time point when an amplitude voltage of FE1 firstly generated
since the up action of the lens exceeds a defined threshold
(referred to as TH) stored in the ROM 39 of the multiple layer disk
type of the reproducing apparatus, until a time point when the lens
is moved up to the maximum set position.
[0101] T2 is a time required from a time point when an amplitude
voltage of FE2 firstly generated since the down action of the lens
exceeds the threshold TH, until a time point corresponding to an
end of the S-shaped characteristics of the FE2. T3 is a time
required from a time point when an amplitude voltage of a second
FE1 exceeds the threshold TH, until a time point when the lens is
moved down to a set end position in the down action of the lens. In
FIG. 3C, T4 is a time required for a tracking balance adjustment to
be firstly performed described later. T5 is a time required for a
tracking gain adjustment to be firstly performed.
[0102] FIGS. 4A to 4C show operation time charts in a case that the
optical pickup 22 is moved to a second layer, similarly to the case
of FIGS. 3A to 3C. T6 is a time required from a time point when the
amplitude voltage of the FE1 firstly generated since the up action
of the lens exceeds the defined TH stored in the ROM 39 of the
multiple-layer disk type of the reproducing apparatus, until a time
point corresponding to an end of the S-shaped characteristics of
the FE1.
[0103] T7 is a time required from a time point when an amplitude
voltage of a second focus error signal FE2 exceeds the threshold
TH, until a time point when the lens is moved up to the maximum set
position. T8 is a time required from a time point when the
amplitude voltage firstly generated since the down action of the
lens exceeds the threshold TH, until a time point when the lens is
moved down to the set end point in the down action of the lens. In
FIG. 4C, T9 is a time required for a tracking balance adjustment to
be performed for the second layer. T10 is a time required for a
tracking gain adjustment to be performed for the second layer.
[0104] The operation of the first embodiment according to the
present invention is explained with reference to flow charts shown
in FIGS. 5 and 6. At first, it is judged at a step S1 whether or
not the optical disk is set. If the optical disk is set, various
data set when previously reproducing the optical disk is
initialized at a step S2. That is, values of counters and timers
(which are not shown) are reset which are incorporated within the
multiple-layer disk type of the reproducing apparatus used from
now.
[0105] A disk discrimination of various disks is performed at a
step S3. The operation of the disk discrimination is explained with
reference to flow charts in FIGS. 12 and 13 described later in
detail. The lens is moved down to a defined position at a step S4.
A number that the lens is repeated to be moved up and down is
counted at a step S5. Each time the lens is moved up or down, one
is added to the number. A value of N at that time is stored in an
RAM 42. The lens is moved up at a defined speed at a step S6. A
defined threshold (referred to as TH), which is stored in advance
in the ROM 39 of the multiple-layer disk type of the reproducing
apparatus, is compared with the obtained FE value at the step S6.
In a case that the FE value is not obtained (step S7: NO), the
operation flow returns to the step S6. The lens is continued to be
moved up at the defined speed. If the obtained FE1 complies with
FE1.gtoreq.TH (step S7: YES), the operation flow proceeds to a step
S8. The timer starts a counting operation for the time T1.
[0106] Next, the maximum amplitude value FEp-p of the FE1 at N= a
first time is taken in at a step S9, and stored in the RAM 42. At a
step S10, it is judged whether or not the counted time by the timer
exceeds the defined time T1. If it is judged that the counted time
does not exceed the defined time T1 (Step S10; NO), the lens is
continued to be moved up until the counted time by the timer
reaches the defined time T1. If it reaches the defined time T1
(Step S10; YES), the operation flow proceeds to a step S11, one is
added to the N, and further the lens is moved down at a step S12.
Next, the operation flow proceeds to a step S13, and it is judged
whether or not the FE value in the second layer obtained when the
lens is moved down is equal to or more than the threshold TH. If
the FE value is equal to or less than the threshold TH (Step S13;
NO), this indicates that the FE resulting from the 0 order light is
not obtained yet in the output of the RF Amp 23. Thus, the
operation flow returns to the step S12, and the lens is continued
to be moved down. If the FE value exceeds the threshold TH (Step
S13; YES), the operation flow proceeds to a step S14, and this
causes the timer to start the counting operation for the defined
time T2.
[0107] In a case where it is judged at a step S15 that the counted
time T by the timer reaches the defined time T2 (step S12: YES),
the operation flow proceeds to a step S16, and the FE value equal
to or more than the threshold TH is detected. The FE value detected
at this step indicates the FE1 of the first layer when the lens is
moved down. At a time point when an amplitude value of the FE1
crosses the TH level, this causes the timer to start the counting
time for the defined time T3 (Step S17). Next, the maximum
amplitude value FEp-p of the FE1 at N=a second time is taken in at
a step S18, and stored in the RAM 42. Then, at a step S19, it is
judged whether or not the counted time T by the timer exceeds the
defined time T3. If it exceeds the defined time T3 (step S19: YES),
the operation flow proceeds to a step S20, and the number N that
the lens is moved up and down is monitored. If the number N is less
than 4 (Step S20; NO), the operation flow returns to the step S5,
and then the maximum amplitude value of the FE1 associated with the
up and down action of the lens is continued to be taken in.
[0108] On the other hand, if the number N exceeds 4 (Step S20;
YES), the operation flow proceeds to a step S21, and the focus gain
is adjusted for the first layer. At this time, the adjusted gain
value is determined by the maximum amplitude value of the FE1, in
the up and down action of the lens, which is stored in the RAM 42
at the steps S9 and S18. For example, in a case that the up and
down action of the lens is performed four times, the maximum
amplitude values of the FE1s of the four samples are stored in the
RAM 42. Thus, an average value of these maximum amplitude values of
the four samples is calculated, and then the servo gain is set such
that this average value becomes a predetermined amplitude value.
Incidentally, the example in which the number of the up and down
actions of the lens is 4 is explained in this embodiment. However,
it is not limited to this number. So, it is possible to properly
change the number as the occasion demands.
[0109] Next, after the lens is moved up to a position at which the
FE1 in the first layer is adjacent to a zero-cross point (Step
S22), a servo close signal is outputted by the servo controller 38.
The PWM 29 generates a pulse signal for driving a focus coil on the
basis of the output signal from the FGA 27, that is, the focus
error signal, corresponding to the servo close signal outputted by
the servo controller 38. In this way, since the PWM 29 becomes
active, a focus servo loop is made close (Step S23). Then, the
operation flow proceeds to a step S24, and this causes the timer to
start the counting time for the defined time T4. Next, in order to
detect a center level (TRCL) of the tracking error (TE) signal, for
example, the maximum peak value and the minimum peak value of the
TE signal are taken in, and a difference thereof is calculated.
[0110] This difference is corresponding to an offset amount from a
zero level of the TE signal center, that is, a balance drift amount
in a differential circuit and the like for generating the TE
signal. In this embodiment, these offset amounts are obtained for a
plurality of samples, and an averaged amount thereof is assumed to
be the center level of the TE signal (Step S25). The defined time
T4 is set to a time at which the sample value of the TE signal
enough to detect the average center level can be taken in. This
detecting operation of the center level of the TE signal is
repeated until the counted time by the timer reaches the defined
time T4 at a step S26 (NO). In a case that the counted time by the
timer exceeds the defined time T4 at the step S26 (YES), the
operation flow proceeds to a step S27. Then, a tracking balance is
adjusted through the TRBL circuit 43 such that the TRCL becomes the
zero level on the basis of the offset amount determined at the step
S25.
[0111] Next, the operation flow proceeds to a step S28, and this
causes the timer to start the counting operation for the defined
time T5. Next, the operation flow proceeds to a step S29, and the
TEp-p is taken in which is the maximum amplitude value of the TE
signal. This take-in operation is repeated until the counted time T
by the timer reaches the defined time T5 (Step S30: NO). At this
time, an averaging process is performed for the maximum amplitude
values which are repeatedly taken in. In a case that the counted
time T by the timer exceeds the defined time T5 at the step S30
(YES), the operation flow proceeds to a step S31, and the tracking
gain is adjusted. The gain value to be adjusted is determined by
the maximum averaged amplitude value of the TE signals determined
at the step S29. That is, the servo gain is set such that the
maximum averaged amplitude value becomes a predetermined amplitude
value. Next, the operation flow proceeds to a step S32, and the
servo close signal is outputted by the servo controller 38 such
that the tracking servo loop is made close. The PWM 36 generates a
pulse signal for driving a tracking coil on the basis of the output
signal from the TGA 34, that is, the tracking error signal,
corresponding to the servo close signal outputted by the servo
controller 38.
[0112] In this way, since the PWM 36 becomes active, the tracking
servo loop is made close. Next, the operation flow proceeds to a
step S33 in FIG. 6. Then, the various adjustment values (the
maximum amplitude value of the focus error signal, the adjustment
value of the focus gain, the center level of the tracking error
signal, the adjustment value of the tracking balance, the maximum
amplitude value of the tracking error signal, the adjustment value
of the tracking gain and the like) in relation to the focus servo
and the tracking servo to the first layer determined at the steps
S1 to S32 are stored in predetermined addresses to store the
information of the first layer in the RAM 42. Incidentally, the
example of setting the servo gain has been explained in this
embodiment. However, it is possible to change the gain as well as
an equalizer value corresponding to each of the record layers to
thereby optimize it. At this time, the equalizer value is also
stored in the RAM 42.
[0113] Next, the operation flow proceeds to a step S34, and
parameters, counter values and the like are initialized which are
used to determine the defined values to the first layer. Next, the
operation flow proceeds to a step S35, and the lens is moved down
to a defined position. Then, one is added to the value N indicative
of the repetition number of the up or down actions of the lens, and
the lens is moved up at the defined speed (Steps S36 and S37).
Next, at a step S38, it is judged whether or not the FE value
complying with the condition of FE1.gtoreq.TH is obtained similarly
to the step S7. If it is not obtained (Step S38; NO), the operation
flow returns to the step S37, and the lens is continued to be moved
up.
[0114] On the other hand, if the FE value is obtained (Step S38;
YES), the operation flow proceeds to a step S39, and this causes
the timer to start the counting operation for the defined time T6.
After the elapse of the defined time T6 at a step S40 (YES), the
operation flow proceeds to a step S41, and it is performed to
detect the FE value equal to or more than the threshold TH.
[0115] The FE value detected at this step S41 indicates the FE2 of
the second layer when the lens is moved up. At a time point when an
amplitude value of the FE2 crosses the TH level, this causes the
timer to start the counting operation for the defined time T7 (Step
S42). Next, the maximum amplitude value FEp-p of the FE2 at N=a
first time is read out and taken in at a step S43, and stored in
the RAM 42. Then, at a step S44, it is judged whether or not the
counted time by the timer exceeds the defined time T7. If it is
judged that the counted time does not exceed the defined time T7
(Step S44; NO), the lens is continued to be moved up until the
counted time by the timer reaches the defined time T7. If it
reaches the defined time T7 (Step S44; YES), the operation flow
proceeds to a step S45, and one is added to the N. Further, the
lens is moved down at a step S46.
[0116] Next, the operation flow proceeds to a step S47, and it is
judged whether or not the FE value in the second layer determined
when the lens is moved down is equal to or more than the threshold
TH. If the FE value is equal to or less than the threshold TH (Step
S47; NO), this indicates that the FE resulting from the 0 order
light is not obtained yet in the output of the RF Amp 23. Thus, the
operation flow returns to the step S46, and the lens is continued
to be moved down. If the FE value exceeds the threshold TH (Step
S47; YES), the operation flow proceeds to a step S48. This causes
the timer to start the counting operation for the defined time T8.
Then, the maximum amplitude value FEp-p at N=a second time is taken
in at a step S49, and stored in the RAM 42. At a step S50, it is
judged whether or not the counted time T by the timer exceeds the
defined time T8. If it exceeds the defined time T8 (step S50: YES),
the operation flow proceeds to a step S51, and the number N that
the lens is moved up and down is monitored. If the number N is less
than 4 (Step S51; NO), the operation flow returns to the step S36,
and then the maximum amplitude value of the FE2 associated with the
up and down action of the lens is continued to be taken in.
[0117] On the other hand, if the number N exceeds 4 (Step S51;
YES), the operation flow proceeds to a step S52, and the focus gain
is adjusted for the second layer. At this time, the adjusted gain
value is determined by the maximum amplitude value of the FE2, in
the up and down action of the lens, which is stored in the RAM 42
at the steps S43 and S49. For example, in a case that the up and
down action of the lens is performed four times, the maximum
amplitude values of the FE1s of the four samples are stored in the
RAM 42. Thus, an average value of the maximum amplitude values of
the four samples is calculated, and then the servo gain is set such
that this average value becomes a predetermined amplitude
value.
[0118] Next, after the lens is moved up (step S53) to a position at
which the FE2 of the second layer is adjacent to a zero-cross
point, the servo close signal is outputted by the servo controller
38 (Step S54). The PWM 29 generates the pulse signal for driving
the focus coil on the basis of the output signal from the FGA 27,
that is, the focus error signal, corresponding to the servo close
signal outputted by the servo controller 38. In this way, since the
PWM 29 becomes active, the focus servo loop is made close (Step
S54). Then, the operation flow proceeds to a step S55, and this
causes the timer to start the counting operation for the defined
time T9. Next, in order to detect the center level (TRCL) of the
tracking error (TE) signal, for example, the maximum peak value of
the TE signal is taken in, and a difference thereof is calculated.
This difference is corresponding to the offset amount from the zero
level of the TE signal center, that is, the balance drift amount in
the differential circuit for generating the TE signal.
[0119] In this embodiment, these offset amounts are determined for
a plurality of samples, and the averaged amount thereof is assumed
to be the center level of the TE signal (Step S56). The defined
time T9 is set to the time at which the sample values of the TE
signal enough to detect the average center level can be taken in.
This detecting operation of the center level of the TE signal is
repeated until the counted time by the timer reaches the defined
time T9 at a step S57. In a case that the counted time by the timer
exceeds the defined time T9 at the step S57(YES), the operation
flow proceeds to a step S58, and then the tracking balance is
adjusted through the TRBL circuit 43 such that the TRCL becomes the
zero level on the basis of the offset amount determined at the step
S56.
[0120] Next, the operation flow proceeds to a step S59, and this
causes the timer to start the counting operation for the defined
time T10. Next, the operation flow proceeds to a step S60, and the
TEp-p is taken in which is the maximum amplitude value of the TE
signal. This take-in operation is repeated until the counted time T
by the timer reaches the defined time T10 (Step S61). At this time,
the averaging process is performed for the maximum amplitude values
which are repeatedly taken in. In a case that the counted time T by
the timer exceeds the defined time T10 at the step S61 (YES), the
operation flow proceeds to a step S62, and the tracking gain is
adjusted. The gain value to be adjusted is determined by the
maximum averaged amplitude value of the TE signals determined at
the step S60. That is, the servo gain is set such that the maximum
averaged amplitude value is the predetermined amplitude value.
[0121] Next, the operation flow proceeds to a step S63, and the
servo close signal is outputted by the servo controller 38 such
that the tracking servo loop is made close. The PWM 36 generates
the pulse signal for driving the tracking coil on the basis of the
output signal from the TGA 34, that is, the tracking error signal,
corresponding to the servo close signal outputted by the servo
controller 38. In this way, since the PWM 36 becomes active, the
tracking servo loop is made close. Next, the operation flow
proceeds to a step S64. Then, the various adjustment values (the
maximum amplitude value of the focus error signal, the adjustment
value of the focus gain, the center level of the tracking error
signal, the adjustment value of the tracking balance, the maximum
amplitude value of the tracking error signal, the adjustment value
of the tracking gain and the like) in relation to the focus servo
and the tracking servo to the second layer determined at the steps
S34 to S63 are stored in predetermined addresses to store the
information of the second layer in the RAM 42.
[0122] Thanks to the operations at the steps S33 to S64, the
adjustment values in relation to the optimal focus servo for the
respective record layers in the two-layer disk are stored in
predetermined addresses corresponding to the respective record
layers in the memory RAM 42. Next, in order to transfer the pickup
to a start position (for example, the innermost circumference track
of the first layer) of the record information recorded on the
two-layer disk, after reading out the adjustment values of the
first layer stored in the predetermined addresses of the RAM 42
(Step S65), a focus jump operation is performed at a step S66. That
is, a focal position of the reading beam is shifted from the record
layer of the second layer to that of the first layer, or from the
record layer of the first layer to that of the second layer. The
initial operation (setup operation) to the two-layer disk 20 loaded
on the reproducing apparatus is completed in accordance with the
above mentioned operations (step S67).
[0123] Incidentally, the focus jump operation is performed as
described below. At first, the tracking servo loop is made close.
Then, the focus servo loop is made open. After the lens is forced
to be transferred in a focus direction (a direction vertical to the
disk record surface) by a predetermined length (a distance between
the layers), the closing action of the focus servo is performed.
The closing action of the tracking servo is successively performed,
and the pickup is moved to search to a desired track as the
occasion demands. In this way, after the focus servo and the
tracking servo are once made open in conjunction with the focus
jump, when they are again made close, the adjustment values are
used which correspond to the record layer of a jumped destination
read out from the RAM 42. Thus, even during reproducing, in a case
of performing the jump operation from the record layer in the first
layer to that in the second layer or the record layer in the second
layer to that in the first layer, it is possible to read out the
various adjustment values corresponding to the record layer at the
jumped destination from the RAM 42 prior to the jump operation to
thereby adjust the servo gain on the basis of the read adjustment
values in the servo closing operation after the jump operation. As
a result, it is possible to quickly perform the stable servo
control.
[0124] [IV] Second Embodiment of the Invention
[0125] In a second embodiment of the present invention, focus error
signals are successively extracted, which are generated from the
first and second layers, among focus error signals generated by
applying the UP or DOWN operation to the objective lens while
emitting light beams to the one-sided two-layer disk loaded on the
disk loading surface of the reproducing apparatus. A gain value is
set for a focus servo on the basis of each of these focus error
signals. After that, a gain value setting is performed for a
tracking servo on the basis of a tracking error signal of the first
layer. Next, a focus jump is performed to the second layer, and a
gain value setting is performed for a tracking servo on the basis
of a tracking error signal of the second layer. The above mentioned
operation is also performed as a setup (initial setting) operation
prior to the actual reproduction operation.
[0126] An operation of the second embodiment according to the
present invention is explained with reference to the block diagram
of FIG. 1, operation time charts in FIGS. 7A to 7C and flow charts
of FIGS. 8 and 9.
[0127] At first, FIG. 7A shows two focus error signals (FE)
detected by the optical pickup 22 when the lens is moved up and
down (in a case of two layers). In FIG. 7A, a symbol N indicates a
number at which the lens is moved up and down. As shown in FIG. 7A,
T1 is a time required from a time point when the amplitude voltage
of FE1 (of the first layer) firstly generated since the up action
of the lens exceeds a defined threshold TH stored in the ROM 39 of
the multiple layer disk type of the reproducing apparatus, until a
time point corresponding to an end of the FE1. T2 is a time
required from a time point when an amplitude voltage of the FE2 (of
the second layer) exceeds the threshold TH, until a time point when
the lens is moved up to the maximum set position.
[0128] T3 is a time required from a time point when the amplitude
voltage of the FE2 (of the second layer) exceeds the threshold TH
until a time point corresponding to an end of the S-shaped
characteristics of the FE2, as for the case of moving down the
lens. T4 is a time required from a time point when the amplitude
voltage of the FE1 (of the first layer) exceeds the threshold TH,
until a time point when the lens is moved down to the maximum set
position. In FIG. 7B, T5 is a time required for a tracking balance
adjustment to be firstly performed for the first layer, and T6 is a
time required for a tracking gain adjustment for the first layer.
Similarly in FIG. 7C, T7 is a time required for a tracking balance
adjustment for the second layer, and T8 is a time required for a
tracking gain adjustment for the second layer.
[0129] The operation of the second embodiment according to the
present invention is explained with reference to flow charts shown
in FIGS. 8 and 9.
[0130] At first, it is judged at a step S101 whether or not the
optical disk is set. If the optical disk is set (step S101: YES),
various data set when previously reproducing the optical disk is
initialized at a step S102. That is, values of counters and timers
(which are not shown) are reset which are incorporated within the
multiple-layer disk type of the reproducing apparatus used from
now.
[0131] A disk discrimination of various disks is performed at a
step S103. The operation of the disk discrimination is explained
later in detail. The lens is moved down to a defined position at a
step S104. Then, the lens is moved up at a defined speed at a step
S105. At a step S106, a number N that the lens is repeated to be
moved up and down is counted, and a number M that the FE is taken
in is counted. Then, at a step S107, a defined threshold TH, which
is stored in advance in the ROM 39 of the multiple-layer disk type
of the reproducing apparatus, is compared with the obtained FE
value. In a case that the FE value is not obtained (step S107: NO),
the lens is continued to be moved up. If the obtained FE1 complies
with FE1.gtoreq.TH (step S107: YES), the operation flow proceeds to
a step S108. The timer starts a counting operation for the time
T1.
[0132] This counting operation in the timer for the defined time T1
is started at a time point when the amplitude of the FE1 crosses
(exceeds) the TH level. The defined time T1 is set in the ROM 39
etc. in advance as a time until the first FE is finished. Next, the
maximum amplitude value FEp-p of the FE of the first layer is taken
in at a step S109, and stored in the RAM 42. At a step S110, it is
judged whether or not the counted time by the timer exceeds the
defined time T1. If it is judged that the counted time does not
exceed the defined time T1 (Step S110; NO), the lens is continued
to be moved up until the counted time by the timer reaches the
defined time T1. If it reaches the defined time T1 (Step S110;
YES), the operation flow proceeds to a step S111. One is added to
the number M, and the operation flow proceeds to a step S112. Then,
it is judged whether or not the FE value of the second layer is
equal to or more than the threshold TH. If the FE value is less
than the threshold TH (Step S112; NO), the moving up operation of
the lens is continued until the FE value exceeds the threshold TH.
If the FE value exceeds the threshold TH (Step S112; YES), the
operation flow proceeds to a step S113.
[0133] At a step S113, the timer starts the counting operation for
the defined time T2. Then, the maximum amplitude value FEp-p of the
FE of the second layer is taken in at a step S114, and stored in
the RAM 42. At a step S115, it is judged whether or not the counted
time by the timer exceeds the defined time T2. In a case where it
is judged at the step S115 that the counted time T by the timer
reaches the defined time T2 (step S115: YES), the operation flow
proceeds to a step S116, and the lens is moved down. Then, one is
added to each of the numbers N and M at a step S117. Next, at a
step S118, it is judged whether or not the FE value of the second
layer is equal to or more than the threshold TH. If the FE value is
less than the threshold TH (step S118: NO), it is continued to move
down the lens until the FE value exceeds the threshold TH. If the
FE value exceeds the threshold TH (step S118: YES), the operation
flow proceeds to a step S119, and the timer starts the counting
operation for the defined time T3. Then, the maximum amplitude
value FEp-p of the FE of the second layer is taken in, and stored
in the RAM 42 at a step S120. Then, at a step S121, it is judged
whether or not the counted time T by the timer exceeds the defined
time T3. If it exceeds the defined time T3 (step S121: YES), the
operation flow proceeds to a step S122, and one is added to the
number M.
[0134] Next, at a step S123, it is judged whether or not the FE
value of the first layer is equal to or more than the threshold TH.
If the FE value is less than the threshold TH (step S123: NO), it
is continued to move down the lens until the FE value exceeds the
threshold TH. If the FE value exceeds the threshold TH (step S123:
YES), the operation flow proceeds to a step S124, and the timer
starts the counting operation for the defined time T4. Then, the
maximum amplitude value FEp-p of the FE of the first layer is taken
in, and stored in the RAM 42 at a step S125. Then, at a step S126,
it is judged whether or not the counted time T by the timer exceeds
the defined time T4. If it exceeds the defined time T4 (step S126:
YES), the operation flow proceeds to a step S127, and the number N
that the lens is repeated to be moved up and down is monitored. If
the number N is less than 4 (step S127: NO), the operation flow
returns to the step S105.
[0135] On the other hand, if the number N exceeds 4 (Step S127;
YES), the operation flow proceeds to a step S128, and the focus
gains are adjusted for the first and second layers. Then, at a step
S129, the adjusted focus gains for the first and second layers are
stored into the RAM 42. After that, the lens is moved up at a step
S30. Then, at a step S31, the PWM 29 generates a pulse signal for
driving a focus coil on the basis of the output signal from the FGA
27, and the focus servo loop is made close by the servo controller
38.
[0136] Then, the operation flow proceeds to a step S132, and this
causes the timer to start the counting time for the defined time
T5. Next, in order to detect a center level (TRCL) of the tracking
error (TE) signal, for example, the maximum peak value and the
minimum Peak value of the TE signal are taken in, and a difference
thereof is calculated (step S133) in FIG. 9. This difference is
corresponding to an offset amount from a zero level of the TE
signal center, that is, a balance drift amount in a differential
circuit and the like for generating the TE signal.
[0137] In this embodiment, these offset amounts are obtained for a
plurality of samples, and an averaged amount thereof is assumed to
be the center level of the TE signal (Step S133). The defined time
T5 is set to a time at which the sample value of the TE signal
enough to detect the average center level can be taken in. This
detecting operation of the center level of the TE signal is
repeated until the counted time by the timer reaches the defined
time T5 at a step S134 (NO). In a case that the counted time by the
timer exceeds the defined time T5 at the step S134 (YES), the
operation flow proceeds to a step S135. Then, a tracking balance is
adjusted through the TRBL circuit 43 such that the TRCL becomes the
zero level on the basis of the offset amount determined at the step
S133.
[0138] Next, the operation flow proceeds to a step S136, and this
causes the timer to start the counting operation for the defined
time T6. Next, the operation flow proceeds to a step S137, and the
TEp-p is taken in which is the maximum amplitude value of the TE
signal. This take-in operation is repeated until the counted time T
by the timer reaches the defined time T6 (Step S138: NO). At this
time, an averaging process is performed for the maximum amplitude
values which are repeatedly taken in. In a case that the counted
time T by the timer exceeds the defined time T6 at the step S138
(YES), the operation flow proceeds to a step S139, and the tracking
gain is adjusted. The gain value to be adjusted is determined by
the maximum averaged amplitude value of the TE signals determined
at the step S137. That is, the servo gain is set such that the
maximum averaged amplitude value becomes a predetermined amplitude
value. Next, the adjusted tracking gain for the first layer is
stored into the RAM 42 at a step S140. Then, the focus jump
operation is performed at a step S141. That is, a focal position of
the reading beam is shifted from the record layer of the first
layer to that of the second layer.
[0139] Next, after the lens is moved up to a position at which the
FE2 of the second layer is adjacent to a zero-cross point, the
servo close signal is outputted by the servo controller 38 (Step
S142). The PWM 29 generates the pulse signal for driving the focus
coil on the basis of the output signal from the FGA 27, that is,
the focus error signal, corresponding to the servo close signal
outputted by the servo controller 38. In this way, since the PWM 29
becomes active, the focus servo loop is made close (Step S142).
Then, the operation flow proceeds to a step S143, and this causes
the timer to start the counting operation for the defined time T7.
Next, in order to detect the center level (TRCL) of the tracking
error (TE) signal, for example, the maximum peak value of the TE
signal is taken in, and a difference thereof is calculated. This
difference is corresponding to the offset amount from the zero
level of the TE signal center, that is, the balance drift amount in
the differential circuit for generating the TE signal.
[0140] In this embodiment, these offset amounts are determined for
a plurality of samples, and the averaged amount thereof is assumed
to be the center level of the TE signal (Step S144). The defined
time T7 is set to the time at which the sample values of the TE
signal enough to detect the average center level can be taken in.
This detecting operation of the center level of the TE signal is
repeated until the counted time by the timer reaches the defined
time T7 at a step S145. In a case that the counted time by the
timer exceeds the defined time T7 at the step S145 (YES), the
operation flow proceeds to a step S146, and then the tracking
balance is adjusted through the TRBL circuit 43 such that the TRCL
becomes the zero level on the basis of the offset amount determined
at the step S144.
[0141] Next, the operation flow proceeds to a step S147, and this
causes the timer to start the counting operation for the defined
time T8. Next, the operation flow proceeds to a step S148, and the
TEp-p is taken in which is the maximum amplitude value of the TE
signal. This take-in operation is repeated until the counted time T
by the timer reaches the defined time T8 (Step S149). At this time,
the averaging process is performed for the maximum amplitude values
which are repeatedly taken in. In a case that the counted time T by
the timer exceeds the defined time T8 at the step S49 (YES), the
operation flow proceeds to a step S150, and the tracking gain is
adjusted. The gain value to be adjusted is determined by the
maximum averaged amplitude value of the TE signals determined at
the step S148. That is, the servo gain is set such that the maximum
averaged amplitude value is the predetermined amplitude value.
Next, the operation flow proceeds to a step S151, and the servo
close signal is outputted by the servo controller 38 such that the
tracking servo loop is made close. The PWM 36 generates the pulse
signal for driving the tracking coil on the basis of the output
signal from the TGA 34, that is, the tracking error signal,
corresponding to the servo close signal outputted by the servo
controller 38.
[0142] In this way, since the PWM 36 becomes active, the tracking
servo loop is made close. Next, at a step S152, the adjusted
tracking gain for the second layer is stored. Finally, the setup of
the multiple layer disk substrate is ended (step S53).
[0143] In the second embodiment, although the explanations have
been made for a case where only the gains for focusing and tracking
are adjusted and stored, it is also possible in the second
embodiment that the equalizer values etc. can be adjusted and
stored in the same manner as the first embodiment.
[0144] In this way, according to the second embodiment, it is
possible to more speedily set the gain value than the first
embodiment, since the focus error signals for obtaining the loop
gain value of the focus servo loop of each layer are all taken in
by one up and down movement of the lens.
[0145] [V] Third Embodiment of the Invention
[0146] Although the focus jump is performed to the second layer in
order to extract the tracking error signal of the second layer in
the case of the second embodiment of the present invention, a third
embodiment of the present invention is a method of setting the
focus and tracking gain values in the first and second layers
without performing the focus jump.
[0147] The third embodiment of the present invention is explained
with reference to the block diagram of FIG. 1 and the flow charts
of FIGS. 8 to 10.
[0148] In the third embodiment, the steps S101 to S132 in FIG. 8
and the steps S133 to S140 in FIG. 9 as for the processes of
adjusting the focus gain value for the first layer, the focus gain
value for the second layer and the tracking gain value for the
first layer in the second embodiment are performed at first.
[0149] From the step S140 of FIG. 9, the operation flow proceeds to
a step S241 in FIG. 10. In FIG. 10, the same steps as those in FIG.
9 carry the same reference numerals and the explanations thereof
are omitted.
[0150] At a step S241, the servo controller 38 determines a ratio
of the average value of the maximum amplitude values of the focus
errors of the first layer to the average value of the maximum
amplitude values of the focus errors of the second layer, for
example, among the FEp-p values taken in at the steps S109, S114,
S120 and S125. Then, it is stored in the RAM 42 as a value A. Next,
at a step S242, the tracking gain for the second layer is
calculated by multiplying the value A stored at the step S241 by
the tracking gain value for the first layer, and is stored in the
RAM 42 as the tracking gain value for the second layer at a step
S243.
[0151] As mentioned above, since the tracking gain for the second
layer is determined on the basis of the ratio of the amplitude
values of the focus errors in the respective layers, it is possible
to save the adjusting time for the tracking gain for the second
layer. Although the ratio is calculated on the basis of the
amplitude values of the focus errors in the respective layers in
this embodiment, it is naturally possible to get the same effect,
even if calculating the ratio from the values of the focus gains in
the respective layers stored at the step S129.
[0152] Although the third embodiment of the present invention has
been explained as the variation of the second embodiment, the
method of the third embodiment of the present invention can be also
applied to the first embodiment of the present invention. That is,
after the focus jump is performed to the second layer, the focus
error signal obtained from the second layer is extracted, and the
gain is set. After that, the method of the third embodiment of the
present invention can be used in the tracking.
[0153] [VI] Disk Discrimination Method of the Invention
[0154] The disk discrimination method used in the above mentioned
flow charts is represented by a lens exchanging type of a disk
discrimination method shown in a flow chart of FIG. 11, and by a
disk discrimination method of using a bifocal lens shown in a flow
chart of FIG. 12.
[0155] (1) Lens Exchanging Type of Disk Discrimination Method
[0156] At first, in FIG. 11, a lens 1 is set to the optical pickup
at a step S301. Next, at a step S302, the lens is moved up to a
defined position. After that, the lens is moved down at a defined
speed at a step S303. At a step S304, a focus error signal is
detected, and the obtained FE value is compared with a threshold
TH1 that is one of predetermined thresholds. If the obtained FE
value exceeds the threshold TH1 (step S304: YES), the focus error
signal is again detected at a step S305. At the step S305, a
threshold TH2 that is another one of the predetermined thresholds
is compared with the FE, separately from the step S304.
[0157] The two thresholds TH1 and TH2 are defined on the basis of
the difference between the maximum amplitude values of the FEs
generated in the CD and the DVD at a time of using the lens 1
respectively. That is, the threshold TH1 is used for the CD, and
the threshold TH2 is used for the DVD. Therefore, in a case that
the loaded optical disk is the DVD, it complies with a condition of
FE.gtoreq..vertline.TH1.vertline. at the step S304. On the other
hand, if it does not comply with a condition of
FE.gtoreq..vertline.TH2.vertline. at the step S305 (NO), it is
discriminated as the CD. Moreover, at a step S306, it is required
to set D=2, and the operation flow proceeds to a step S312. Then,
the down action of the lens is stopped. If it complies with the
condition of FE.gtoreq..vertline.TH2.vertline. at the step S305
(YES), it is judged as the first layer of the DVD, and thereby D=1
is set at a step S307. After that, the timer T2 is set at a step
S308. This timer T2 is set to this required value, since it waits
for a time when the S shape in the first layer is completed, in a
case of the multiple-layer disk.
[0158] A generation time of the FE is monitored at a step S309. If
the FE exceeding the threshold TH2 is again generated at a step
S310, it is discriminated as the two-layer disk at a step S311, and
D= 3 is set. If it complies with a condition of T2.gtoreq.t at the
step S309 (YES), this means that there is no S shape of the FE in
the second layer. Thus, the operation flow proceeds to the step
S312, and then the down action of the lens is stopped. The value D
is checked at a step S313 (YES), so that if D=1, it is
discriminated as a one-layer disk of 0.6 mm. Or, if D=3 at the step
S313 (YES), it is discriminated as a two-layer disk of 0.6 mm. So,
the disk discrimination is finished at a step S315. If D=2 at the
step S313 (NO), it is discriminated as a 1.2 mm disk. So, the lens
2 is set at a step S314, and the disk discrimination is finished at
the step S315.
[0159] (2) Disk Discrimination Method When Using Bifocal Lens
[0160] FIG. 12 shows a disk discrimination method in a case of
using the bifocal lens. In FIG. 12, the lens is firstly moved up to
a defined position at a step S401. After that, the lens is moved
down at a defined speed at a step S402. At a step S403, a focus
error signal is detected, and the obtained FE is compared with a
threshold TH1 that is one of predetermined thresholds. If the
obtained FE value exceeds the threshold TH1 (step S403: YES), the
focus error signal is again detected at a step S404. At the step
S404, a threshold TH2 that is one of the predetermined thresholds
is compared with the FE, separately from the step S403. The two
thresholds TH1 and TH2 are defined on the basis of the difference
between the maximum amplitude values of the FEs generated by the 0
order light or the +1 order light in the CD and the DVD at a time
of using the bifocal lens respectively.
[0161] That is, the threshold TH1 is used for the CD, and the
threshold TH2 is used for the DVD. Thus, in a case that the loaded
optical disk is the DVD, it complies with the condition of
FE.gtoreq..vertline.TH1.vertli- ne. at a step S403 (YES). If it
does not comply with the condition of
FE.gtoreq..vertline.TH2.vertline. at a step S404 (NO), it is
discriminated as the CD. At a step S405, it is required to set D=2,
and the operation flow proceeds to a step S411. Then, the down
action of the lens is stopped. If it complies with the condition of
FE.gtoreq..vertline.TH2.vertline. at the step S404 (YES), it is
judged as the first layer of the DVD, and thereby D= 1 is set at a
step S406. After that, the timer T2 is set at a step S407. This
timer T2 is set to this required value, since it waits for the time
when the S shape in the first layer is completed, in a case of the
multiple-layer disk.
[0162] A generation time of the FE is monitored at a step S408. If
the FE exceeding the threshold TH2 is again generated at a step
S409 (YES), it is discriminated as the two-layer disk at a step
S410, and D=3 is set. If it complies with the condition of
T2.gtoreq.t at the step S409, this means that there is no S shape
of the FE of the second layer. Thus, the operation flow proceeds to
a step S411, and then the down action of the lens is stopped. The
value D is checked at a step S412. If D=1, it is discriminated as
the one-layer disk of 0.6 mm. Or, if D=3, it is discriminated as
the two-layer disk of 0.6 mm. So, the disk discrimination is
finished at a step S412.
[0163] The CD, the DVD (one-layer) and the DVD (two-layer) are
discriminated by the above mentioned disk discrimination method.
The DVD (two-layer) is used in this embodiment, for example.
[0164] [VII] Fourth Embodiment of the Invention
[0165] A fourth embodiment of the present invention is a method of
setting the focus and tracking gain values as well as the gain
value for the RF signal.
[0166] FIGS. 13 and 14 show flow charts in which the gain for the
RF signal is adjusted, and show portions that are not included in
the flow charts used in the first and second embodiments of the
present invention. At first, the fourth embodiment is explained
with reference to FIG. 13. At a step S501, the focus gains for the
first and second layers are automatically adjusted as indicated in
the above mentioned embodiments. Then, the focus loop of the first
layer is made close at a step S502. After that, the tracking gain
for the first layer is adjusted at a step S503. Then, the tracking
loop is made close at a step S504. The maximum amplitude value of
the RF signal of the first layer is taken in at a step S505. The
gain value is calculated by the RGA 48 and the servo controller 38,
and stored in the RAM 42 at a step S506.
[0167] Next, the focus and tracking loops are made open at a step
S507. The operation flow proceeds to the second layer at a step
S508. Since operations at the steps S509 to S513 for the second
layer are similar to those at the steps S503 to S507 for the first
layer, the explanations thereof are omitted.
[0168] After that, the focus gain value, the tracking gain value
and the RF gain value for the first layer stored in the RAM 42 are
read out at a step S514. Then, the focus is again made open and the
jump is performed to the first layer at a step S515. The focus and
tracking loops are made close at a step S516. At a step S517, the
multiple-layer disk type of the reproducing apparatus is made in a
play state so as to perform a reproduction. If the reproduction of
the loaded disk is completed or a stop command is issued at a step
S518 (YES), the operation is ended. On the other hand, when the
stop command is not issued at the step S518 (NO), and if a command
to jump to another layer is issued at a step S519 (YES), the
tracking and focus loops are made open at a step S520, and the
focus gain value, the tracking gain value and the RF gain value for
another layer are read out at a step S521. Then, the jump to
another layer is performed at a step S522, and the operation flow
returns to the step S517 so as to perform the play of the
multiple-layer. If the play is completed (step S18: YES), the
reproduction is ended.
[0169] As mentioned above, since the gain values for the RF signals
in the respective layers are also set and stored, it is possible to
make the respective servos stable at a time of reproducing to
thereby accurately reproduce the signal.
[0170] [VIII] Fifth Embodiment of the Invention
[0171] A fifth embodiment of the present invention is a method of
taking in the maximum amplitude signal of the RF signal without
making the tracking loop close, as a modification of the fourth
embodiment of the present invention.
[0172] The fifth embodiment of the present invention is explained
with reference to FIG. 14. Since operations at steps S601 to S603
are same as the steps S501 to 503 of FIG. 13, the explanations
thereof are omitted. At a step S604, the maximum amplitude value of
the RF signal of the first layer is read while the tracking open
state is kept. Then, the gain is calculated by the RGA 48 and the
servo controller 38, and stored in the RAM 42 at a step S605.
[0173] Next, the focus loop is made open at a step S606, and the
jump to the second layer is performed at a step S607. Since
operations of steps S608 to S610 for the second layer are similar
to those of steps S603 to S605 for the first layer, the
explanations thereof are omitted. After that, the focus loop is
made open at a step S611. Then, the focus gain value, the tracking
gain value and the RF gain value for the first layer stored in the
RAM 42 are read out at a step S612. The jump to the first layer is
performed at a step S613, and the focus and tracking loops are made
close at a step S614. Since operations at steps S615 to S620 are
the same as to those at the steps S517 to S522 in FIG. 13, the
explanations thereof are omitted.
[0174] As mentioned above, in the fifth embodiment of the present
invention, the maximum amplitude values of the RF signals in the
respective layers are taken in while the tracking is kept in the
open state. Thus, the adjustment time is shorter than that of the
fourth embodiment of the present invention to thereby make the
setting operation quicker.
[0175] [IX] Sixth Embodiment of the Invention
[0176] A sixth embodiment of the present invention is a method of
preparing and storing a set value of the gain value for the RF
signal for each disk and each layer in advance, as a modification
of the fifth embodiment of the present invention.
[0177] The sixth embodiment of the present invention is explained
with reference to FIG. 15. Since operations at steps S701 to S703
are the same as those at the steps S601 to 603 of FIG. 14, the
explanations thereof are omitted. At a step S704, the gain value
for the RF signal of the first layer is read and set, which is
stored in the ROM 39 in advance as defined value for each disk and
each layer. The focus loop is made open at a step S705, and the
jump to the second layer is performed at a step S706. After the
tracking gain is adjusted at a step S707, the gain value for the RF
signal of the second layer is read and set, which is stored in the
ROM 39 in advance, similarly to the case of the first layer, at a
step S708. The focus loop is made open at a step S709, and the jump
to the first layer is performed at a step S710. Then, the focus
gain value, the tracking gain value and the RF gain value for the
first layer stored in the RAM 42 are read out at a step S711. Then,
the focus and tracking loops are made close at a step S712.
Operations on and after a step S713 are the same as those at the
steps S615 to S620 in FIG. 14. Thus, the explanations thereof are
omitted.
[0178] As mentioned above, in the sixth embodiment of the present
invention, the gain value for the RF signal is prepared and stored
as a set value for each disk and each layer in advance. Thus, the
adjustment time is shorter than that of the fifth embodiment of the
present invention to thereby make the setting operation
quicker.
[0179] Although the example of adjusting the focus and tracking
gains as well as the RF gain has been explained in the embodiments,
it is naturally possible to adjust only the RF gain. Further, it is
allowable to: extract a signal in a particular frequency band, for
example, 3T (minimum time width) through the RGA 48 and the servo
controller 38 or extract only the 3T through the BPF (Band Pass
Filter); perform an A/D conversion thereof; take in a level of the
3T; send it to the RGA 48; and make the level of at least the 3T
frequency up, so as to simultaneously perform the equalizer
adjustment or perform only the equalizer adjustment. Accordingly,
this enables an eye pattern of the RF signal to be open, and a
proper spindle servo to be performed, to thereby improve the signal
reading capability.
[0180] In the embodiments, as shown in FIGS. 13 or 14, the maximum
amplitude value of the RF signal is read by the tracking close
circuit/open circuit, and thereby the gain of the RF signal is
adjusted. However, in a case of generating the RF signal from a
four-division light converter (not shown) within the optical pickup
22 similarly to the focus error, it is possible to read the maximum
amplitude value of the focus errors of the first and second layers
and set and store the gain values for the RF signals of the
respective layers from this value, to thereby achieve the similar
effect.
[0181] More concretely, in this case, a standard value as for a
level of the FE of a standard disk, for example, for each of
layers, is stored in the RAM 42 in advance, and the standard value
of each layer is compared with the FE value of each layer, so that
the gain value as a ratio to the RF signal for each layer is set
and stored.
[0182] Further, in the embodiments, the RF gains are adjusted and
stored only for the first and second layers of the two-layer disk.
However, as for the first layer disk of the DVD or the CD, it is
also allowable to adjust, store and use the respective gain values
for the focus, the tracking and the RF, and/or the equalizer value.
Further, in a case of measuring the focus and tracking gain values
and/or the equalizer value to thereby adjust and store them, the
set value may be prepared in advance for each disk and each layer
with respect to the RF gain value and/or the equalizer value, and
stored in the ROM 39. Then, this set value may be used without
performing the adjustment.
[0183] Furthermore, in order to cope with a flaw of a disk during
measuring or adjusting the gain value and/or the equalizer value,
the flaw detecting circuit (not shown) may be separately mounted,
so that the measurement can be stopped until the flaw is solved, or
the measurement can be performed again.
[0184] Incidentally, in a case of producing a disk in which one
pair of the above mentioned two-layer disks are formed on both
sides thereof, it is possible to store the adjustment values in the
respective record layers as well as surface discrimination
information thereof, so as to perform a quick correspondence even
if a disk reproduction surface is changed. Further, by storing the
information peculiar to the disk with the adjustment value, it is
possible to discriminate the peculiar information at a time of
reproducing, so as not to perform the initial setting operation
again with respect to the disk, to which the initial setting
operation has been once performed.
[0185] [X] Seventh Embodiment of the Invention
[0186] At first, a seventh embodiment of the present invention is
explained with reference to FIGS. 16 to 21. Although an apparatus
of this embodiment is a DVD/CD compatible type of a reproducing
apparatus, a case of reproducing the DVD as an information record
medium is explained in this embodiment.
[0187] FIG. 16 shows a block diagram indicating a schematic
configuration of the reproducing apparatus of this embodiment. In
FIG. 16, an optical disk 101 is the DVD as one example of the
information record medium. In the optical disk 101, information is
recorded on an information track by using, for example, a phase pit
or a magnetic record mark. An optical spot is formed by light beams
from a laser diode (not shown) included in an optical pickup 102 as
one example of a reading device.
[0188] A reflection light of this optical spot is inputted to a
receiving optics such as a four-division photo detector (not shown)
included in the optical pickup 102 and the like, as a reflection
light to which astigmatism is given. A detection signal is
outputted from the receiving optics.
[0189] An RF Amplifier 103, which is a constitutional element of
one example of a reproduction process device, generates an RF
(Radio Frequency) signal from the detection signal outputted by the
receiving optics of the optical pickup 102, and also outputs a
focus error signal FE and a tracking error signal TE.
[0190] This RF signal is inputted to a spindle driver 105 as a
standard signal to achieve a synchronization for a spindle motor
106 after the RF signal is demodulated and corrected by a
demodulation and correction circuit 104, and is also inputted to a
video circuit 107 and an audio circuit 108, respectively, as a
video signal and an audio signal. Accordingly, a video output and
an audio output can be generated, respectively.
[0191] On the other hand, the focus error signal FE and the
tracking error signal TE are outputted from a servo circuit 110
controlled by a CPU 109 as one example of a control device, to a
focus driver 111 and a tracking driver 112 as one example of a
drive device, respectively, as a focus drive signal FD and a
tracking drive signal TD. Accordingly, a focus servo and a tracking
servo are performed. The servo operation by this servo circuit 110
is switched between a close state and an open state by a servo
control signal FS0N from the CPU 109. A gain up signal GUP for
making a servo sensibility higher is also outputted from the CPU
109 to the servo circuit 110. Moreover, the focus drive signal FD
and the tracking drive signal TD are controlled and outputted by
the servo circuit 110 when the servo is close. A focus jump signal
and a rising/lowering signal of the focus are outputted by an
output command from the CPU 109 when the servo is open. For this
reason, a RAM 113 in which a pulse width of the focus drive signal
FD and the like are stored is connected to the CPU 109.
[0192] An operation panel 114 is connected to the CPU 109.
Operation information, such as start or stop of the reproduction of
the optical disk 1 and the like, are inputted through the operation
panel 114 to the CPU 109. Incidentally, a signal for indicating
whether or not the optical disk 1 is loaded is also inputted to the
CPU 109 through a sensor and the like, although this mechanism is
not shown in FIG. 16.
[0193] In a case of the reproducing apparatus of this embodiment
having the above mentioned configuration, it is necessary to jump
an objective lens of the optical pickup 102 from one information
record layer to another information record layer in order to
reproduce the optical disk having multiple layers. This jump is
performed by outputting a kick pulse as the focus drive signal FD
as shown in FIG. 17, to the focus driver 111. A kick pulse height
i.e. peak to peal (p-p) value and a pulse width of this kick pulse
are set from the viewpoints of an interval between the information
record layers and a moving amount of the objective lens. For
example, it is possible to make the peak value larger and the pulse
width shorter, to thereby jump the objective lens to a target
position more quickly.
[0194] In case of outputting the kick pulse, the servo control
signal FS0N is outputted from the CPU 109 to the servo circuit 110
to thereby make the servo open, and then an output request of the
focus drive signal FD is issued so as to output a kick pulse with a
predetermined pulse width and peak value to the servo circuit 110.
Accordingly, a kick pulse as shown in FIG. 17 is outputted from the
servo circuit 110 to the focus driver 111. Then, the objective lens
of the optical pickup 102 is jumped by a predetermined amount
corresponding to a drive signal based on the kick pulse from the
focus driver 111. If the objective lens is jumped, for example,
from a lower portion to an upper portion, it is moved upward from a
focal point by the kick pulse. Thus, for example, an upward focus
error signal FE is generated. Further, when it is faced to a focal
point in a second layer, a downward focus error signal FE is
generated. Therefore, the focus is made close at a position at
which this downward focus error signal FE is generated. So, the CPU
109 detects the zero cross of this focus error signal FE to thereby
output the servo control signal FS0N to the servo circuit 110 so as
to make the servo close. Moreover, the CPU 9 outputs to the servo
circuit 110 the gain up signal GUP for transiently making a focus
gain larger, so as to stabilize the focus coil at the jumped point.
An output time for this gain up signal GUP is referred to as a gain
up time.
[0195] Furthermore, in order to suddenly stop the optical pickup at
the jumped point, a brake pulse may be applied to the focus driver
111 as the focus drive signal FD after the jump pulse, as shown in
FIG. 18. Since a moving part is tried to be suddenly stopped also
in this case, there may be a possibility that a focus coil cannot
become quickly stable. Thus, such a method is performed in which
not only the brake pulse is applied, but also the focus gain is
transiently made higher until it becomes stable.
[0196] As mentioned above, it is necessary to set the pulse width,
the peak value, the brake pulse width and the gain up time to
predetermined values, in order to jump the optical pickup to
thereby reproduce the multiple-layer disk. In a case that the
interval between the information record layers is not known, it is
necessary to set an average pulse width, peak value, brake pulse
width and gain up time and to output the kick pulse to thereby
detect the zero cross signal of the focus error signal FE. Thus, in
a case that these values are not appropriate, for example, in a
case that the interval between the layers is longer than an average
interval, and in other cases, an excess time is required until the
servo is made close.
[0197] However, by examining relations between the moving amount of
the objective lens and the pulse width, the peak value, the brake
pulse width and the gain up time in advance, it is possible to
select an appropriate pulse width and the like in accordance with
the interval between the layers to thereby jump the objective lens
in the shortest time.
[0198] Then, this embodiment is constituted so as to store in
advance the pulse width, the peak value, the brake pulse width and
the gain up time which correspond to the several intervals between
the layers, and measure the intervals between the layers in the
information record layers immediately after loading the optical
disk and then read out the pulse width and the like corresponding
to the measured interval between the layers when switching between
the information record layers, to thereby jump the objective lens
of the optical pickup 102 to the target position quicker and much
accurate.
[0199] In this embodiment, the pulse width, the peak value, the
brake pulse width and the gain up time which correspond to the
interval between the layers are measured in advance, and stored in
a ROM and the like (which are not shown) within the CPU 109 as a
table. Then, the pulse width and the like corresponding to the
interval between the layers are selected from the table at a
predetermined time, and stored in the RAM 113. That is, the CPU 109
and the RAM 113 are used as one example of a selection device and
one example of a parameter memory respectively, in this
embodiment.
[0200] Next, a method of measuring the interval between the layers
in this embodiment is explained. At first, the optical pickup 102
used in the apparatus of this embodiment is explained in detail.
The optical pickup 102 of this embodiment comprises, for example, a
bifocal lens as shown in FIG. 19.
[0201] The optical pickup 102 comprising this bifocal lens has a
structure in which it is possible to emit two light beams focused
on different positions on one straight line. That is, in the
bifocal lens, a diffraction grating H and an objective lens R are
arranged on one optical path, as shown in FIG. 19. Light beams made
parallel to each other by a collimator lens (not shown) are divided
into three beams: a 0 order light and .+-.1 order lights, by the
diffraction grating H. Utilization of a difference between the
optical path lengths of the 0 order light and the +1 order light
among them enables the 0 order light and the +1 order light to be
focused on the different positions on one straight line.
[0202] Actually, the +1 order light is adapted to be focused on a
farther position from the objective lens R than the 0 order light.
The 0 order light is set so as to be optimally collected on the
information record surface of the DVD, and further the +1 order
light is set to be optimally collected on the information record
surface of the CD. The utilization of the optical pickup having
such a bifocal lens enables the apparatus of this embodiment to
reproduce both of the CD and the DVD.
[0203] In the two light beams from the optical pickup 102 having
the bifocal lens, the +1 order light is set to be optimally
collected on the CD, and the 0 order light is set to be optimally
collected on the DVD. Accordingly, the +1 order light is longer in
focal length. Thus, for example, as shown in FIG. 19, when the
bifocal lens is moved up for the multiple-layer DVD, the +1 order
light is firstly collected on a first layer of the information
record surface of the DVD, and then a focus error signal is
detected. Next, it is collected on a second layer of the
information record layer, and the similar focus error signal is
detected. A pseudo focus error signal is detected which is
generated since a reflection light from the first layer of the +1
order light is routed through an optical path of the 0 order light.
Moreover, the similarly pseudo focus error signal is detected by a
reflection light from the second layer. Finally, a focus error
signal is detected from the first layer corresponding to the 0
order light. Furthermore, a focus error signal is also detected
from the second layer.
[0204] As mentioned above, in the multiple-layer disk, a total of
six focus error signals are generated by using the optical pickup
102 having the bifocal lens. However, by setting a threshold TH
which is larger than a peak value of the pseudo focus error signal
and smaller than a peak value of the focus error signal for the 0
order light, a focus error signal exceeding the threshold TH is
only the focus error signal for the 0 order light. Thus, since a
moving speed of the optical pickup is constant, it is possible to
measure an interval between the occurrences of the bifocal error
signals for this 0 order light to thereby measure an interval
between the first layer and the second layer in the information
record layers.
[0205] That is, a timer as one example of a time counting device is
actuated at a time of detecting the focus error signal larger than
the threshold TH. Then, the timer is stopped at a time of detecting
a next focus error signal. Accordingly, it is possible to determine
an interval between two successive focus error signals. Assuming
that a value determined by the timer counting action is t, and that
a constant based on the up and down moving speed of the objective
lens is a. Then, X=t/a is a value peculiar to an interval between
layers. By the CPU 109 as one example of the calculation device,
for example, if X is defined by a following expression (1) as:
1.6.ltoreq.X.ltoreq.2.5 (1)
[0206] the interval between the layers is judged as 40 .mu.m. Or,
if X is defined by a following expression (2) as:
2.6.ltoreq.X.ltoreq.3.5 (2)
[0207] the interval between the layers is judged as 60 .mu.m. When
t=4 msec, and if a=2, the loaded disk is discriminated as a disk
having an interval of 40 .mu.m since X=4 msec/2=2, in this
example.
[0208] A measured interval between the focus error signals may be
from a time point when the focus error signal exceeds the
predetermined threshold TH, to a time point when the next focus
error signal exceeds the threshold TH, as shown in FIG. 20A.
Alternatively, by setting the thresholds at an upper side and a
lower side as shown in FIG. 20B, the measured interval may be from
a time point when a first rising portion of the focus error signal
exceeds the threshold at the upper side, to a time point when a
second trailing portion of the focus error signal drops below the
threshold at the lower side.
[0209] Next, operations of the apparatus of this embodiment are
explained with reference to FIGS. 19 and 21. Incidentally,
respective processes shown in FIG. 21 are mainly performed by the
CPU 109. Timers T1 and T2 described later as one example of a time
counting device are built in the CPU 109.
[0210] As shown in FIG. 21, it is firstly judged whether or not the
disk is set (Step S801). If the disk is judged to be set, a content
of the RAM 113 and the timers T1 and T2 are cleared, and a register
and the like included in the CPU 109 are initialized (Step S802).
Next, the objective lens is moved down to a lower limit shown in
FIG. 19 (Step S803). After the objective lens arrives at the lower
limit, an operation of the timer T1 is started (Step S804) in order
to check the arrival of the objective lens to an upper limit.
Moreover, the objective lens is moved up (Step S805). As for a
focus error signal detected during the up action (refer to FIG.
19), it is judged whether or not any of the peak values exceeds the
threshold TH (Step S806). If the peak value exceeds the threshold
TH (Step S806; YES), an operation of the timer T2 is started (Step
S807) in order to measure a time required until a next peak value
exceeds the threshold TH. Next, it is judged whether or not the
next peak value exceeds the threshold TH (Step S808). If it exceeds
(Step S808; YES), the operation of the timer T2 is finished (Step
S809).
[0211] After that, the operation waits until the value of the timer
T1 exceeds a predetermined value t1 (Step S810). If it exceeds
(Step S810; YES), it is judged that the objective lens is moved to
the upper limit. The timer T1 is stopped (Step S811), and the up
action of the objective lens is stopped (Step S812).
[0212] The interval between the information record layers is
determined from the aforementioned judgment expressions (1) and (2)
on the basis of the value of the timer T2 (Step S813). At least one
value among the pulse width, the peak value, the brake time and the
gain up time for the optimal kick pulse is selected from the table,
on the basis of the interval between the layers. Then, it is stored
in the RAM 113 (Step S814).
[0213] Since the value to jump the objective lens is stored as
mentioned above, unless the disk is replaced after that, it is
possible to output a control signal to the servo circuit 110 on the
basis of the stored value to thereby jump the objective lens to a
position suited for each of the information record layers
accurately and quickly.
[0214] [XI] Eighth Embodiment
[0215] Next, an eighth embodiment of the present invention is
explained with reference to FIGS. 22 and 23. Incidentally,
identical reference numbers are assigned to parts common to the
seventh embodiment. Then, the explanations thereof are omitted.
[0216] In this embodiment, a disk discrimination is performed at
the same time when the interval between the layers is measured as
mentioned above. For example, it is discriminated that any of the
one-layer DVD, the multiple-layer DVD and the CD is loaded. Thus,
the CPU 109 functions as one example of a discrimination device in
this embodiment.
[0217] Since a structure of a hardware of this embodiment is the
same as that of the seventh embodiment, the explanation thereof is
omitted. Then, a control in this embodiment is explained with
reference to FIGS. 22 and 23.
[0218] As shown in FIG. 22, it is firstly judged whether or not the
disk is set (Step S820). If the disk is judged to be set (YES), the
following initializations are performed. That is, a content of the
RAM 113 is cleared, and registers included in the CPU 109, for
example, a register D and a counter E described later are cleared
(Step S821). Next, the objective lens is moved down to a lower
limit shown in FIG. 23 (Step S822). After the objective lens
arrives at the lower limit, the operation of the timer T1 is
started (Step S823) in order to check the arrival of the objective
lens to an upper limit. Further, the objective lens is moved up
(Step S824). As for a focus error signal detected during the up
action (refer to FIG. 23), it is judged whether or not any of the
peak values exceeds a threshold TH1 (refer to a symbol TH1 in FIG.
23) (Step S825). If the peak value exceeds the threshold TH1 (Step
S825; YES), operations of the timers T2 and T4 are started (Step
S826).
[0219] This timer T2 is used to measure the interval between the
layers in a case that the loaded disk is the multiple-layer DVD,
similarly to the seventh embodiment. The timer T4 is used to
perform the discrimination between the one-layer DVD and the
CD.
[0220] Next, it is judged whether or not a next peak value exceeds
the threshold TH1 (Step S827). Before the timer T1 reaches the
predetermined value t1, that is, when the objective lens does not
arrive at the upper limit (Step S828; NO), if it exceeds the
threshold TH1 (Step S827; YES), the loaded disk can be
discriminated as the two-layer DVD as shown in FIG. 23. Then, the
operation of the timer T2 is finished similarly to the seventh
embodiment (Step S829). The operation waits until the value of the
timer T1 exceeds the predetermined value t1 (Step S830).
[0221] On the other hand, even if the timer T1 reaches the
predetermined value t1, when the peak does not exceed the threshold
TH1 (Step S827; NO, and Step S828; YES), the loaded disk can be
discriminated as the one-layer DVD or the CD as shown in FIG. 23.
Then, the value of the timer T2 is cleared (Step S831).
[0222] If the timer T1 reaches the predetermined value t1 as
mentioned above, it is judged that the objective lens arrives at
the upper limit. Thus, the operation of the timer T1 is finished.
Further, an operation of a timer T3 is started (Step S832) in order
to check the arrival of the objective lens to the lower limit.
Then, the objective lens is started to be moved down (Step
S833).
[0223] It is judged whether or not the peak value again exceeds the
threshold TH1 (Step S834). If it exceeds the threshold TH1 (Step
S834; YES), an operation of a timer T4 is finished (Step S835). As
shown in FIG. 23, an interval t41 at which the FE peak values are
generated in a case that the disk is the one-layer DVD is shorter
than an interval t42 at which the FE peak values are generated in a
case of the CD.
[0224] Next, the operation waits until the timer T3 reaches a
predetermined value t3 (Step S836). If it is judged that the timer
T3 reaches the predetermined value t3 and the lens arrives at the
lower limit (Step S836; YES), the operation of the timer T3 is
finished (Step S837). A content of the timer T2 is judged (Step
S838) in order to discriminate the loaded disk as the
multiple-layer disk or the one-layer disk.
[0225] As mentioned above, in a case of the one-layer disk, the
content of the timer T2 is already cleared. Thus, it is possible,
by judging whether or not the content of the timer T2 exceeds 0
(Step S838), to discriminate it as the one-layer or multiple-layer.
Namely, if the content of the timer T2 exceeds 0 (Step S838; YES),
the loaded disk is discriminated as the multiple-layer DVD,
similarly to the seventh embodiment. The interval between the
layers is determined from the aforementioned judgment expressions
(1) and (2) on the basis of the value of the timer T2, similarly to
the seventh embodiment (Step S839). At least one value among the
pulse width, the peak value, the brake time and the gain up time
for the optimal focus jump is selected from the table, on the basis
of the interval between the layers. Then, it is stored in the RAM
113 (Step S840).
[0226] On the other hand, if the content of the timer T2 is 0 (Step
S838; NO), the loaded disk is discriminated as the one-layer disk.
Since it is necessary to discriminate the loaded disk as the DVD or
the CD, it is judged whether or not the value of the timer T4 is
equal to or more than a predetermined value t4 (Step S841). This
predetermined value t4 is set to a middle value between the peak
value interval in the case of the DVD and the peak value interval
in the case of the CD, as shown in FIG. 23. If it is equal to or
more than the predetermined value t4, the loaded disk can be
discriminated as the DVD. If it is less than the t4, the loaded
disk can be discriminated as the CD.
[0227] Therefore, if it is more than the t4 (Step S841; NO), the
loaded disk is discriminated as the DVD, and 2 is set to the
register D (Step S842). Further, a focus gain, a tracking gain and
an equalizer for the DVD are set (Step S843). On the other hand, if
it is equal to or less than the t4 (Step S841; YES), the loaded
disk is discriminated as the CD, and 1 is set to the register D
(Step S844). Further, a focus gain, a tracking gain and an
equalizer for the CD are set (Step S845).
[0228] Since all of the disk discriminations are finished, the
objective lens is again moved up (Step S846) in order to make the
focus servo close. Then, a number that the peak value exceeds a
threshold TH2 is counted to thereby judge the detected light as the
0 order light or the +1 order light. In case of the DVD, the focus
is locked by the 0 order light. In case of the CD, the focus is
locked by the +1 order light. Namely, by setting this threshold TH2
to a value smaller than the peak value of the focus error signal
for the +1 order light of the DVD, as shown in FIG. 23, in a case
of the one-layer DVD, the focus is made close when the peak value
of the focus error signal by the 0 order light exceeds the
threshold TH2 at a third time. In a case of the multiple-layer DVD,
the focus is made close when it exceeds the threshold TH2 at a
fifth time. Or, in a case of the CD, the focus is made close when
it exceeds the threshold TH2 at a first time.
[0229] Then, it is judged whether or not the value of the register
D is 0 (Step S847) in order to initialize and set the values of the
registers and the counters, immediately after the objective lens is
moved up. If the D is 0 (Step S847; YES), an input to the register
D is not performed, and thereby the loaded disk can be
discriminated as the multiple-layer disk. Thus, a value of the
counter E is set to 0, and a value of the register b is set to 5
(Step S848). On the other hand, if the register D is not 0 (Step
S847; NO), the loaded disk can be discriminated as the one-layer
DVD or the CD, as mentioned above. Therefore, the value of the
counter E is set to 0, and the value of the register b is set 3
(Step S849).
[0230] Then, it is judged whether or not the peak value exceeds the
threshold TH2 (Step S850). If it exceeds the threshold TH2 (Step
S850; YES), the counter E is incremented (Step S851). Next, the
register D is judged (Step S852). Namely, if the register D is 1
(YES), the loaded disk is discriminated as the CD. Thus, in order
to make the focus servo close when the focus error signal for the
+1 order light is generated, this count process by the counter E is
withdrawn (Step S852; YES). However, if the register D is 0 or 2,
the loaded disk is discriminated as the DVD. Then, it is necessary
to make the focus close when the focus error signal for the 0 order
light is generated. Thus, the counting action of the counter E is
repeated until the value of the counter E becomes the value of the
register b set as mentioned above (Step S852; NO, and Step S853;
NO).
[0231] After it is judged that the peak value of the focus error
signal for the +1 order light or the 0 order light exceeds the
threshold TH2 as mentioned above, the focus servo is made close
(Step S854), and the tracking servo is made close (Step S855).
Then, the reproduction is started (Step S856). If a stop command is
issued (Step S857; YES), the reproduction is finished.
[0232] As mentioned above, parameters such as the pulse width of
the kick pulse to jump the objective lens and the like are stored
for the multiple-layer DVD. Thus, unless the disk is replaced after
that, it is possible to jump the objective lens based on the stored
parameters to thereby jump to a position corresponding to each of
the information record layers accurately and quickly. Moreover, it
is possible to perform the discrimination for the multiple-layer
DVD, the one-layer DVD and the CD to thereby perform the correct
focus servo control.
[0233] [XII] Ninth Embodiment
[0234] Next, a ninth embodiment of the present invention is
explained with reference to FIGS. 24 to 27. Incidentally, identical
reference numbers are assigned to parts common to the seventh
embodiment. Then, the explanations thereof are omitted. This
embodiment performs a focus gain adjustment and a tracking gain
adjustment for each of the layers in the multiple-layer DVD, and
simultaneously measures the interval between the layers.
[0235] FIG. 24 shows a block diagram indicating a schematic
structure of the servo circuit 110 of the reproducing apparatus
shown in FIG. 16. The other configuration of the reproducing
apparatus of this embodiment is the same as the apparatus shown in
FIG. 16. As shown in FIG. 24, an LPF (Low Pass Filter) 120 removes
unnecessary frequency components equal to or more than a sampling
frequency of an A/D converter 122 described later, from the focus
error signal FE.
[0236] An amplifier 121 amplifies the focus error signal FE up to a
predetermined voltage value to output it, and also changes the
amplified amount on the basis of a focus servo gain from an FGA 123
described later.
[0237] The A/D converter 122 converts the focus error signal FE
amplified by the amplifier 121 into a digital signal, outputs it to
the next FGA 123 and also outputs this digitized focus error signal
FE to a servo controller 132 described later.
[0238] The FGA 123 applies feedback to the amplifier 121 on the
basis of the focus error signal FE outputted by the A/D converter
122, and automatically adjusts a focus servo loop gain.
[0239] A digital equalizer circuit (D-EQ) 124 is composed of a
digital filter and the like, and sets a focus servo frequency band
corresponding to the focus error signal FE converted into the
digital signal, on the basis of a control signal from the servo
controller 132 described later.
[0240] A PWM (Pulse Width Modulation) circuit 125 generates a focus
drive signal FD having a pulse width corresponding to a signal
level from the digital equalizer circuit 124.
[0241] An LPF 126, an amplifier 127, an A/D converter 128, a TGA
129, a digital equalizer circuit 130 and a PWM 131 are equipped in
order to generate a tracking drive signal TD from a tracking error
signal TE, similarly to the focus servo loop. Then, operations are
performed which correspond to the respective means constituting the
focus servo loop.
[0242] Further, a TRBL 133 is equipped which performs an automatic
control of a tracking balance, on the basis of the control signal
from the servo controller 132, in order to adjust the tracking
balance. This TRBL 33 feeds back to the RF Amplifier 103 a TBC
signal of adjusting a center level of the tracking error
signal.
[0243] The servo controller 132 as one example of a servo
calculation device and a servo controlling device calculates, on
the basis of the focus error signals as described later, peak
values thereof, and further outputs a control signal of setting a
focus servo gain from an average of the peak values, and a control
signal of setting a focus servo frequency band. Moreover, it
calculates, on the basis of the tracking error signals, peak values
thereof, and further outputs a control signal of setting a tracking
servo gain from an average of the peak values, and a control signal
of setting a tracking servo frequency band. Incidentally, data
required to perform the focus servo control and the tracking servo
control and the like are stored in a RAM 135 as one example of a
gain memory.
[0244] A setup operation of the reproducing apparatus of this
embodiment is explained which comprises the servo circuit 110
having the above mentioned structure. As shown in FIG. 25, it is
firstly judged whether or not the disk is set (Step S860). If the
disk is judged to be set (YES), the CPU 109 performs the
initializing actions (Step S861). That is, it clears the content of
the RAM 113 and clears registers included in the CPU 109, for
example, a counter N and a counter M described later, and a timer
of the servo controller 32 and the like.
[0245] Next, the disk discrimination is performed (Step S862). In
this disk discrimination process, the objective lens is firstly
moved to a lower limit as shown in FIG. 27 (Step S62-1).
[0246] In FIG. 27, next, while the objective lens is moved up (Step
S62-2), it is judged whether or not the peak value of the focus
error signal exceeds the threshold TH3 (Step S62-3). This threshold
TH3 is set to a value smaller than the peak value of the focus
error signal for the 0 order light in a case of the CD, as shown in
FIG. 28A. In order to generate a focus error signal shown in FIG.
28A, a light division ratio of the 0 order light to the +1 order
light in the optical pickup 2 is set to, for example, 70% to 30%,
in this embodiment. When setting as mentioned above, a large focus
error signal can be obtained for the 0 order light, even if the
disk is the CD or the DVD. However, the focus error signal in a
case of the DVD is larger than that in a case of the CD. Thus, even
if the peak value of the obtained focus error signal exceeds the
threshold TH3, when it is less than the threshold TH1, the disk can
be discriminated as the CD. When it exceeds the threshold TH1, the
disk can be discriminated as the DVD.
[0247] If the peak value of the focus error signal exceeds the
threshold TH3 (Step S62-3; YES), it is judged whether or not the
peak value further exceeds the threshold TH1 (Step S62-4). If it
does not exceed (Step S62-4; NO), the disk is discriminated as the
CD, and 1 is set to the register D (Step S62-5). On the other hand,
if it exceeds the threshold TH1 (Step S62-4; YES), the operation of
the timer T1 is started (Step S62-6) in order to judge whether or
not the DVD has the multiple layers. Then, it is judged whether or
not the value of the timer T1 reaches the predetermined value t1
and the objective lens arrives at the upper limit (Step S62-7).
Moreover, it is judged whether or not a focus error signal
exceeding the threshold TH1 is generated again before the value of
the timer T1 reaches the predetermined value t1 (Step S62-8). In a
case of the two-layer disk of the DVD, it is possible to obtain the
focus error signal exceeding the threshold TH1 before the objective
lens arrives at the upper limit as shown in FIG. 28A (Step S62-8;
YES). Thus, the disk is discriminated as the two-layer disk, and 3
is set to the register D (Step S62-9). On the other hand, when it
is impossible to obtain the focus error signal exceeding the
threshold TH1 before the timer T1 reaches the predetermined value
t1 (Step S62-7; YES), the disk is discriminated as the one-layer
DVD, and 2 is set to the register D (Step S62-10).
[0248] As mentioned above, after any of the values is set to the
register D, the operation of the timer T1 is finished (Step
S62-11). The up action of the objective lens is finished (Step
S62-12). The objective lens is moved down to the lower limit (Step
S62-13). The disk discrimination process is finished.
[0249] In this embodiment, the following process is performed only
in a case of the two-layer DVD. This reason is that, since the
focus gain values and the tracking values in the first and second
layers are different from each other in case of the two layer DVD,
it is intended to store the focus gain value and the tracking gain
value for each layer to thereby perform the proper focus servo and
tracking servo.
[0250] Therefore, in order to check the discriminated result in the
disk discrimination process, it is judged whether or not the value
of the register D is 3 as shown in FIG. 25 (Step S863).
[0251] In FIG. 25 again, if the register D is not 3 (step S863:
NO), and the disk is discriminated as the one-layer DVD or the CD,
the servo close process is performed similarly to the eighth
embodiment (on and after the step S846 in FIG. 22). Incidentally,
the processes to this point are performed by the CPU 109, and
processes on and after this point are performed by the servo
controller 132, except a particular process.
[0252] On the other hand, If the value of the register D is 3 (step
863: YES) and the disk is discriminated as the two-layer DVD, the
counter N for counting the number of the up and down actions of the
objective lens is incremented, and the counter M for counting the
focus error signals is incremented (Step S864).
[0253] Then, while the objective lens is moved up (Step S865), it
is judged whether or not the focus error signal exceeding the
threshold TH1 is detected during the up action of the lens (Step
S866). The focus error signal exceeding this threshold TH1 is only
the signal for the 0 order light. Only the focus error signal for
the 0 order light is illustrated after the disk discrimination in
FIG. 28A. For an easy explanation, the interval between the focus
error signals after the disk discrimination process is widely
illustrated in FIG. 28A.
[0254] In FIG. 25 again, if the focus error signal exceeding the
threshold TH1 is detected (Step S866; YES), timers T5, T10 are
actuated (Step S867).
[0255] This timer T5 is used to determine a timing of counting one
focus error signal. The timer T10 is used to measure the interval
between the layers in a case that the loaded disk is the
multiple-layer DVD, similarly to the seventh embodiment.
[0256] Next, a peak to peak value FEpp (M) of the focus error
signal is taken in and stored (Step S868). This peak to peak value
FEpp (M) is used to later adjust the focus gain.
[0257] After that, the operation waits until the timer T5 exceeds a
predetermined value t5 (Step S869). If it exceeds, the timer T5 is
finished (Step S870). It is judged that an output of one focus
error signal is finished. Then, the counter M is incremented (Step
S871).
[0258] Next, it is judged whether or not the focus error signal
exceeding the threshold TH1 is detected from the focus error
signals for the second layer (Step S872). If such a focus error
signal is detected (Step S872; YES), an operation of a timer T6 is
started (Step S873) in order to measure an interval up to the upper
limit of the objective lens. Further, the operation of the timer
T10 for measuring the interval between the layers is finished (Step
S874).
[0259] Then, a peak to peak value FEpp (M) of the focus error
signal in this second layer is taken in and stored (Step S875).
After that, the operation waits until the timer T6 reaches a
predetermined value t6 and the objective lens arrives at the upper
limit (Step S876). After that, if it is judged that this timer T6
reaches the predetermined value t6 and the objective lens arrives
at the upper limit (Step S876; YES), the timer T6 is finished (Step
S877).
[0260] In the process to this point, the objective lens is
positioned at the upper limit, as shown in FIG. 28A. The counter N
for counting the up and down actions of the objective lens is 1.
Bifocal error signals are detected during this period. Thus, the
counter M of the focus error signal is 2. Moreover, the peak to
peak values for the respective focus error signals are stored.
[0261] Next, the objective lens is moved down (Step S878). The
counters N and M are incremented (Step S879). Then, it is judged
whether or not the focus error signal exceeding the threshold TH1
is detected from the focus error signals for the second layer in
the down action (Step S880). If the focus error signal exceeding
the threshold TH1 is detected (Step S880; YES), an operation of a
timer T7 for determining a timing of masking the focus error signal
is started (Step S881). The peak to peak value FEpp (M) of the
focus error signal is taken in and stored (Step S882).
[0262] After that, the operation waits until the timer T7 exceeds a
predetermined value t7 (Step S883). If it exceeds, the timer T7 is
finished (Step S884). It is judged that an output of one focus
error signal is finished. Then, the counter M is incremented (Step
S885).
[0263] Next, it is judged whether or not the focus error signal
exceeding the threshold TH1 is detected from the focus error
signals for the first layer (Step S886). If such a focus error
signal is detected (Step S886; YES), an operation of a timer T8 is
started (Step S887) in order to measure an interval down to the
lower limit of the objective lens.
[0264] Then, a peak to peak value FEpp (M) of the focus error
signal in this first layer is taken in and stored (Step S888).
After that, the operation waits until the timer T8 reaches a
predetermined value t8 and the objective lens arrives at the lower
limit (Step S889). If the value of the timer T8 reaches the
predetermined value t8 (Step S889: YES), the timer T8 is finished
(Step S890).
[0265] In the process to this point, the objective lens is
positioned at the lower limit, as shown in FIG. 28A. The counter N
for counting the up and down actions of the lens is 2. Bifocal
error signals are detected during this period. Thus, the counter M
of the focus error signals is 4. Moreover, the peak to peak values
for the respective focus error signals are also stored.
[0266] After that, the above mentioned process is repeated until
the counter N becomes 4 (Step S891; NO, through Step S864). The
process is stopped at a time point when the counter N becomes 4
(Step S891; YES). Thus, peak to peak values of four focus error
signals are obtained respectively for the first layer and the
second layer, at this time point.
[0267] Then, the focus gain value is calculated by calculating an
average of the peak to peak values of the four focus error signals
for each layer. Accordingly, the focus gain is adjusted (Step
S892). Further, the focus gain values of the first and second
layers are stored in the RAM 35.
[0268] Next, the CPU 109 determines the interval between the layers
similarly to the seventh embodiment (Step S894) on the basis of the
previously measured value of the timer T10, and selects at least
one value among the pulse width, the peak value, the brake time and
the gain up time for the optimal focus jump from the table, on the
basis of the interval between the layers, and stores in the RAM 113
(Step S895).
[0269] In FIG. 26, then, the servo controller 132 moves up the
objective lens (Step S896), and makes the focus servo in the first
layer close, on the basis of the above calculated focus gain value
in the first layer (Step S897). Next, an operation of a timer T12
is started (Step S898) in order to adjust the tracking balance in
the first layer. A process of taking in a center level of the
tracking error signal TE (Step S899) as shown in FIG. 28B is
continued until a value of the timer T12 reaches a predetermined
value t12 (Step S900; NO). If the value of the timer T12 reaches
the predetermined value t12 (Step S900; YES), the operation of the
timer T12 is finished (Step S901). The tracking balance in the
first layer is adjusted (Step S902) on the basis of the value of
the center level of the tracking error signal TE taken in the above
manner.
[0270] A timer T13 is actuated (Step S903) in order to adjust the
tracking gain in the first layer. A process of taking in a peak to
peak value TEpp of the tracking error signal TE (Step S904) as
shown in FIG. 28B is continued until a value of the timer T13
reaches a predetermined value t13 (Step S905; NO). If the value of
the timer T13 reaches the predetermined value t13 (Step S905; YES),
the timer T13 is stopped (Step S906). The tracking gain in the
first layer is adjusted (Step S907) on the basis of the value of
the peak to peak value TEpp of the tracking error signal TE taken
in the above manner. The tracking servo is made close (Step S908).
The tracking gain value in the first layer is stored in the RAM 135
(Step S909).
[0271] Next, in order to perform the above similar process for the
second layer, the lens is jumped to a position relative to the
second layer (Step S910), on the basis of the pulse width, the peak
value, the brake time, the gain up time and the like for the
previously stored kick pulse. The focus servo of the second layer
is made close (Step S911) on the basis of the above calculated
focus gain value for the second layer. Next, an operation of a
timer T14 is started (Step S912) in order to adjust the tracking
balance for the second layer. A process of taking in a center level
of the tracking error signal TE (Step S913) as shown in FIG. 28C is
continued until a value of the timer T14 reaches a predetermined
value t14 (Step S914; NO). If the value of the timer T14 reaches
the predetermined value t14 (Step S914; YES), the operation of the
timer T14 is finished (Step S915). The tracking balance in the
second layer is adjusted (Step S916) on the basis of a value of the
center level of the tracking error signal TE taken in the above
manner.
[0272] An operation of a timer T15 is started (Step S917) in order
to adjust the tracking gain for the second layer. A process of
taking in a peak to peak value TEpp of the tracking error signal TE
(Step S918) as shown in FIG. 28C is continued until a value of the
timer T15 reaches a predetermined value t15 (Step S919; NO). If the
value of the timer T15 reaches the predetermined value t15 (Step
S919; YES), the operation of the timer T15 is finished (Step S920).
The tracking gain for the second layer is adjusted (Step S921) on
the basis of a value of the peak to peak value TEpp of the tracking
error signal TE taken in the above manner. The tracking servo is
made close (Step S922). The tracking gain value for the second
layer is stored in the RAM 135 (Step S923).
[0273] It is possible to perform the above mentioned processes to
thereby perform the focus servo control and the tracking servo that
are appropriate and accurate for each of the layers, and also
possible to measure the interval between the two layers in the
single layer to thereby set the optimally jumping condition. As a
result, it is possible to jump between the layers accurately and
quickly.
[0274] In the above mentioned examples, the present invention is
applied to the apparatus which can reproduce both the CD and the
DVD. However, the present invention is not limited to the examples.
The apparatus dedicated to the DVD reproduction is allowable. Thus,
it is not necessary that the optical pickup uses the above
mentioned bifocal lens. It is allowable to use an optical pickup
comprising a single-focus lens. Or, a type of switching between the
respective lens for the CD and the DVD can be used similarly.
[0275] As for a moving direction of the lens at a time of measuring
the interval between the layers, the example in which it is started
from the up direction is explained. However, the present invention
is not limited to the example. It is allowable to be started from
the down direction.
[0276] In this embodiment, the pulse width, the peak value, the
brake time and the gain up time for the focus jump are all
selected, and all stored in the RAM. However, the present invention
is not limited to it. It is allowable to select and store any one
value or several values of them.
[0277] In this embodiment, the focus error signal resulting from
the 0 order light is used to determine the interval between the
layers in each of the record layers. However, it is possible to use
the focus error signal resulting from the +1 order light or the
pseudo light. At that time, an interval between the focus error
signals is determined by properly changing a threshold.
[0278] In a case of a disk in which both surfaces of two layers are
bonded together, it is possible to perform the various adjustments
similar to this embodiment for two layers on an upper side and two
layers on a lower side at a time of a first setup, to thereby
record with layer information in the respective layers. Moreover,
it is naturally possible to store and use a plurality of respective
adjustment values with the information peculiar to the disk.
[0279] The invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The present embodiments are therefore to be considered in
all respects as illustrative and not restrictive, the scope of the
invention being indicated by the appended claims rather than by the
foregoing description and all changes which come within the meaning
and range of equivalency of the claims are therefore intended to be
embraced therein.
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