U.S. patent application number 11/422021 was filed with the patent office on 2006-09-14 for method for adjusting mechanical error of optical disc reading device.
This patent application is currently assigned to BENQ CORPORATION. Invention is credited to Jung-Tsung Cheng, Cheng-Chieh CHUANG.
Application Number | 20060203632 11/422021 |
Document ID | / |
Family ID | 29708460 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060203632 |
Kind Code |
A1 |
Cheng; Jung-Tsung ; et
al. |
September 14, 2006 |
METHOD FOR ADJUSTING MECHANICAL ERROR OF OPTICAL DISC READING
DEVICE
Abstract
The present invention provides a method for adjusting the
mechanical error of an optical disc reading device. The optical
disc reading device consists of a driving device and an optical
pickup. The driving device has a base plate for supporting and
rotating an optical disc. The method consists of moving the optical
pickup to surface of optical disc, the optical pickup emitting two
tracking light spots onto the surface, and the optical pickup
reciprocally moving relative to the surface. Next, the optical
pickup reads reflected signal of two tracking light spots for
generating a track crossing signal. By using the track crossing
signal, the method adjusts position of optical pickup relative to
the base plate.
Inventors: |
Cheng; Jung-Tsung;
(Kaohsiung City, TW) ; CHUANG; Cheng-Chieh;
(Sanchung City, Taipei, TW) |
Correspondence
Address: |
SNELL & WILMER;ONE ARIZONA CENTER
400 EAST VAN BUREN
PHOENIX
AZ
85004-2202
US
|
Assignee: |
BENQ CORPORATION
No. 157, Shan-Ying Rd., Kweishan
Taoyuan
TW
|
Family ID: |
29708460 |
Appl. No.: |
11/422021 |
Filed: |
June 2, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10457640 |
Jun 9, 2003 |
7065011 |
|
|
11422021 |
Jun 2, 2006 |
|
|
|
Current U.S.
Class: |
369/44.28 ;
G9B/7.061; G9B/7.138 |
Current CPC
Class: |
G11B 7/0903 20130101;
G11B 7/082 20130101; G11B 7/22 20130101 |
Class at
Publication: |
369/044.28 |
International
Class: |
G11B 7/00 20060101
G11B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 11, 2002 |
TW |
091112660 |
Claims
1. A method for adjusting mechanical error of optical disc reading
device, said optical disc reading device comprising a driving
device, an optical pickup, said driving device comprising a base
plate for supporting and rotating an optical disc having a surface,
said surface having at least one track, said method comprising:
moving said optical pickup to said surface along said moving trace,
said optical pickup emitting tracking light spots onto said
surface; performing relative movement between said tracking light
spots and said track along said moving trace; generating a track
crossing signal by reading reflected signals from said surface
corresponding to said tracking light spots; and adjusting said
moving trace of said optical pickup relative to said base plate
according to said track crossing signal.
2. The method according to claim 1, wherein said track crossing
signal comprises a sine wave.
3. The method according to claim 2, wherein said adjusting step is
performed to have a maximum value of peak-to-peak of said sine
wave.
4. The method according to claim 2, wherein said sine wave
comprises a plurality of peaks together defining a wave envelope,
said wave envelope comprises a plurality of envelope troughs, and
said adjusting step causes values of said envelope troughs to be
substantially equal to one another.
5. The method according to claim 2, wherein said sine wave
comprises a plurality of troughs together defining a wave envelope,
said wave envelope comprises a plurality of envelope peaks, and
said adjusting step causes values of said envelope peaks to be
substantially equal to one another.
6. The method according to claim 1, wherein said track crossing
signal comprises a cosine wave.
7. The method according to claim 6, wherein said adjusting step is
performed to have a maximum value of peak-to-peak of said cosine
wave.
8. The method according to claim 6, wherein said cosine wave
comprises a plurality of peaks together defining a wave envelope,
said wave envelope comprises a plurality of envelope troughs, and
said adjusting step causes values of said envelope troughs to be
substantially equal to one another.
9. The method according to claim 6, wherein said cosine wave
comprises a plurality of troughs together defining a wave envelope,
said wave envelope comprises a plurality of envelope peaks, and
said adjusting step causes values of said envelope peaks to be
substantially equal to one another.
10. A method for examining a moving trace of an optical pickup of
an optical disc reading device, said optical reading device
comprising a driving device, said driving device including a base
plate for supporting and rotating a disc, said disc having a
surface, said surface having at least one track, said method
comprising: moving said optical pickup along said moving trace to
said surface, for emitting tracking light spots on said surface;
performing relative movement between said track light spots and
said track along said moving trace; reading the reflected signals
of said tracking light spots; calculating said reflected signals to
generate a track crossing signal; and examining if said track
crossing signal is optimized.
11. The method according to claim 10, wherein said track crossing
signal comprises a sine wave.
12. The method according to claim 11, wherein said examining step
examines if a maximum value of peak-to-peak of said sine wave is
obtained.
13. The method according to claim 11, wherein said sine wave
comprises a plurality of troughs together defining a wave envelope,
said wave envelope comprises a plurality of envelope peaks, and
said examining step examines if values of said plurality of
envelope peaks are substantially equal to one another.
14. The method according to claim 11, wherein said sine wave
comprises a plurality of peaks together defining a wave envelope,
said wave envelope comprises a plurality of envelope troughs, and
said examining step examines if values of said plurality of
envelope troughs are substantially equal to one another.
15. The method according to claim 10, wherein said track crossing
signal comprises a cosine wave.
16. The method according to claim 15, wherein said examination step
examines if a maximum value of peak-to-peak of said cosine wave is
obtained.
17. The method according to claim 15, wherein said cosine wave
comprises a plurality of troughs together defining a wave envelope,
said wave envelope comprises a plurality of envelope peaks, and
said examining step examines if values of said plurality of
envelope peaks are substantially equal to one another.
18. The method according to claim 15, wherein said cosine wave
comprises a plurality of peaks together defining a wave envelope,
said wave envelope comprises a plurality of envelope troughs, and
said examining step examines if values of said plurality of
envelope troughs are substantially equal to one another.
19. An optical disc reading apparatus for operating an optical
disc, said optical disc having a surface with at least one track,
comprising: a base plate for supporting and rotating said optical
disc; an optical pickup for emitting tracking light spots on said
surface so that a track crossing signal is generated by reading
reflected signals from said surface corresponding to said tracking
light spots; a guiding unit for providing a moving trace to guide
said optical pickup to said surface; a driving device for moving
said optical pickup along said moving trace; and adjustment unit
for adjusting said moving trace of said optical pickup relative to
said base plate.
20. The optical disc reading apparatus according to claim 19,
wherein said adjustment unit adjusts said moving trace of said
optical pickup relative to said base plate according to said track
crossing signal.
21. The optical disc reading apparatus according to claim 20,
wherein said track crossing signal comprises a sine wave, and said
moving trace is adjusted to obtain a maximum value of peak-to-peak
of said sine wave.
22. The optical disc reading apparatus according to claim 19,
wherein said adjustment unit is configured to horizontally move
said guiding unit relative to said optical disc so as to adjust
said moving trace of said optical pickup relative to said base
plate.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This Application is a continuation of U.S. Utility patent
application Ser. No. 10/457,640 filed on Jun. 9, 2003 and claims
priority to Taiwan Patent Application No. 091112660 filed on Jun.
11, 2002.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for adjusting the
mechanical error. In particular, the present invention relates to a
method for examining and adjusting the mechanical error of an
optical disc reading device.
BACKGROUND OF THE INVENTION
[0003] An optical disc device typically includes tracking servo
control. The optical disc device emits a beam of light to a
particular position of a track on the disc when the optical disc
device records, replays or erases the data of the optical disc. The
optical disc device obtains the tracking error by detecting the
reflected beam from the spot on the optical disc. The tracking
servo control corrects the tracking error to zero, hence the light
spot falls on the accurate position of the track of the optical
disc. There is a detailed description about the technology
correcting tracking error in the U.S. Pat. No. 5,828,634.
[0004] FIG. 1A and FIG. 1B are schematic diagrams for explaining
how to obtain a traditional track crossing signal. As shown in FIG.
1A, the pit track 112 and the land track 114 are disposed
alternatively on the surface of the optical disc 110. Generally,
the data are recorded in the pit track 112. The radial direction of
the optical disc 110 is the track crossing direction which is
presented as arrow "X". The tangential direction of the optical
disc 110 is the rotating direction which is presented as arrow
"Y".
[0005] The traditional three-beam method for obtaining the track
crossing signal is to use a laser to impinge on the surface of the
optical disc 110 and generate three spots on the surface of the
optical disc 110. The main spot 117, the subordinate spot 116 and
the other subordinate spot 118 are substantially located in a line.
The difference in brightness of the reflected light corresponding
to the subordinate spots 116 and 118 approaches to zero when the
main spot 117 falls on a pit track 112.
[0006] As shown in FIG. 1B, when the main spot 117 falls on the
track crossing position, the half part of the main spot 117 falls
on the pit track 112 and the other half part falls on the land
track 114. There is a maximum value of the absolute value of the
difference in brightness of the reflected lights corresponding to
the subordinate spots 116 and 118. By utilizing the difference in
brightness, the track crossing signal can be obtained.
[0007] FIG. 1C is a schematic diagram of a traditional track
crossing signal observed on the oscilloscope. When the optical disc
110 is rotating and the optical pickup is fixed, the reflected
lights corresponding to the subordinate spots 116 and 118 are read,
transformed, and operated to generate a track crossing signal 120.
The track crossing signal 120 shown on the oscilloscope includes a
continuous sine wave and cosine wave and the wave number and the
amplitude relate to the parameters which are set in the
oscilloscope. A wave envelope of wave peak 122 can be obtained by
connecting several wave peaks of the track crossing signal 120.
Also, a wave envelope of wave troughs 124 can be obtained by
connecting several wave troughs of the track crossing signal
120.
[0008] Point "A" is on the wave envelope 122 of wave peaks, point
"B" corresponds to point "A" and is on the wave envelope 124 of
wave troughs. The difference of amplitude of these two points is a
maximum "Am1", and the maximum "Am1" corresponds to the maximum
absolute value of the difference in brightness of reflected lights
corresponding to the subordinate spots 116 and 118 as shown in FIG.
1B.
[0009] However, the defect of the optical disc 110, such as an
eccentric optical disc, makes the resulting track crossing signal
different from the track crossing signal 120 shown in FIG. 1C. The
mechanism and quality of the components of the optical disc device
also cause the track crossing signal to be different from the track
crossing signal 120 shown in FIG. 1C. Thus, it is desired to
improve the disc-reading capability of the optical disc device.
SUMMARY OF THE INVENTION
[0010] One aspect of the present invention provides a method for
adjusting the mechanical error of the optical disc reading device.
The reading efficiency of the optical disc reading device is
improved by the method.
[0011] Another aspect of the present invention provides a method
for examining the mechanical error of the optical disc reading
device. The mechanical error of the optical disc reading device can
be examined by analyzing the track crossing signal.
[0012] Another aspect of the present invention provides an optical
disc reading device for adjusting the mechanical error of the
optical pickup. The optical pickup of the optical disc reading
device is adjusted by the screws according to the fluctuation of
the track crossing signal. The adjustment minimizes the mechanical
error and improves the reading efficiency of the optical disc
reading device.
[0013] The present invention provides a method for adjusting the
mechanical error of the optical disc reading device. The optical
disc reading device includes an optical pickup and a driving device
including a base plate for supporting and rotating an optical disc.
In the first step of the method, the optical pickup is moved to the
surface of the optical disc. In the second step, the optical pickup
emits two tracking light spots onto the surface and the base plate
performs a relative movement between the tracking light spots and
the track on the surface. Next, the optical pickup reads the
reflected light to generate a track crossing signal. The mechanical
error is examined using the track crossing signal and the relative
position between the optical pickup and the base plate is adjusted
according to the track crossing signal.
[0014] The present invention provides an optical disc reading
device for adjusting the mechanical error of the optical pickup.
The optical disc reading device includes an optical pickup, a base
plate and guide bars. The base plate has a center and supports an
optical disc. The guide bars include an end terminal and define a
moving trace. The guide bars guide a relative movement between the
optical pickup and the optical disc. The feature of the optical
disc reading device resides in having at least a screw on the end
terminal. The screw adjusts the guide bars making the moving trace
to pass through the center of the base plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1A and FIG. 1B are schematic diagrams for explaining
how to obtain a traditional track crossing signal;
[0016] FIG. 1C is a schematic diagram showing a traditional track
crossing signal;
[0017] FIG. 2 is a flow chart of the present invention;
[0018] FIG. 3A is a top view of an optical disc reading device for
explaining how the present invention uses an optical disc to
examine the mechanical error of the optical disc reading
device;
[0019] FIG. 3B is a schematic diagram of the track crossing signal
obtained using the device of FIG. 3A;
[0020] FIG. 3C is a side view of an optical disc reading device for
explaining how the present invention uses an optical disc to
examine and adjust the mechanical error of the optical disc reading
device; and
[0021] FIG. 4A and FIG. 4B are schematic diagrams of the track
crossing signal when an eccentric disc is used to examine the
mechanical error of the optical disc reading device.
DETAILED DESCRIPTION
[0022] When illustrating an exemplary embodiment of the present
invention with the provided two-dimensional diagram, persons
skilled in the art can understand the actual configuration of an
optical disc reading device or a disc includes a three-dimensional
construction and these two-dimensional diagrams are not intended to
be construed in a limiting sense. Furthermore, to better illustrate
the present invention, the provided schematic diagrams of optical
disc reading device and track crossing signal are intentionally not
enlarged in the same scale. In addition, to focus on the problem to
be solved by the present invention, the schematic diagrams provided
to illustrate the present invention do not include other irrelevant
components or structures of the optical disc device. The optical
disc device includes other components or structures in actual
operation which are not shown in diagrams presented.
[0023] The present invention is a method for adjusting mechanical
error of an optical disc reading device. The optical disc reading
device includes a driving device and an optical pickup including a
base plate. FIG. 2 is a flow diagram of the present invention. In
step 30, the base plate supports and rotates an optical disc. In
step 32, the optical pickup is moved to the optical disc. In step
34, the optical pickup emits two tracking beams onto the optical
disc. In the step 36, the driving device performs a relative
movement between the optical pickup and the track on the optical
disc. In the present invention, step 34 and step 36 can be
exchanged reversely. In step 38, the optical pickup reads the
reflected light from the surface of optical disc corresponding to
two tracking beams. Same as the prior art, a track crossing signal
is acquired by transforming and calculating the brightness of the
reflected light. The track crossing signal can also be read and
shown on a typical oscilloscope. In step 39, the present invention
utilizes the track crossing signal to determine mechanical error of
the optical disc reading device and adjusts the relative structures
of components of the optical disc reading device by observing
fluctuation of the track crossing signal. For example, a maximum
value of peak-to-peak of track crossing signal is resulted by
changing the relative position between the optical pickup and the
base plate.
[0024] FIG. 3A is a top-view diagram of the major portion of the
optical disc reading device and is used to explain an exemplary
embodiment of the present invention. An optical disc reading device
10 includes a driving device 11 and an optical pickup 12. The
driving device 11 includes a base plate 13 for supporting and
rotating an optical disc (not show in the diagram). The driving
device 11 drives the optical disc to pass through the center 14 of
the base plate 13 and rotates the optical disc around an axle
perpendicular to the surface of the optical disc. The driving
device 11 also includes a device, e.g., a gear wheel (not shown in
the diagram) for performing a relative movement between the optical
pickup 12 and the base plate 13. The base plate 13 includes guide
bars 15 on both sides. The guide bars 15 provide a moving trace and
guide the optical pickup 12 to move along the moving trace. The
guide bars 15 have a support 16 on the ends for connecting the
guide bars 15.
[0025] The embodiment of the invention uses a non-eccentric optical
disc which is placed on the base plate 13. The center of optical
disc coincides with the center 14 of the base plate 13. When the
driving device 11 rotates the optical disc, the pit track and the
land track also rotate along the axle as described above. Then, the
driving device 11 drives the optical pickup 12 to move along to the
guide bars 15. It means that the optical pickup 12 moves relatively
to the base plate 13. When the optical pickup 12 moves to the
surface of the optical disc, the optical pickup 12 emits two
tracking beams and forms two tracking light spots on the surface of
the optical disc. The optical pickup 12 reads the light which is
reflected from the surface corresponding to the two tracking light
spots. The optical disc reading device 10 transforms the brightness
of the reflected light and generates a track crossing signal shown
on the oscilloscope.
[0026] Nevertheless, in the embodiment of the present invention,
the mechanical error of the optical disc reading device 10 causes
the moving trace to not pass through the center 14 of the base
plate 13. Consequently, after transformation and calculation, the
absolute value of the difference of the brightness of the reflected
light is smaller than the maximum value "Am1" depicted in FIG.
1C.
[0027] FIG. 3B is a diagram of the track crossing signal based on
the embodiment. As FIG. 3B shows, a plurality of wave peaks of a
track crossing signal 20 forms a wave envelope 22 and a plurality
of wave troughs of the track crossing signal 20 forms a wave
envelope 24. A point "C" of the wave envelope 22 and a point "D" of
the wave envelope 24 are selected as datum points. The point "C"
corresponds to point "D" and the difference of amplitude is "Am2".
"Am2" is smaller than the maximum value "Am1" in FIG. 1C. The track
crossing signal 20 of this type is easily observed when the optical
pickup 12 moves closer to the center 14.
[0028] The present invention utilizes the track crossing signal 20
obtained to examine mechanical error of the optical disc reading
device 10. The mechanical error causes the moving trace to not pass
through the center 14 of the base plate 13. Furthermore, the
present invention uses the track crossing signal 20 obtained and an
extra adjustment mechanism for reducing the mechanical error of the
optical disc reading device 10. FIG. 3C is a schematic diagram of
an optical disc reading device to illustrate the adjustment
mechanism of the present invention. The screws 17 are provided on
the support 16 to adjust the position of the guide bars 15. Then,
the screws 17 adjust the moving trace to pass through the center 14
of the base plate 13.
[0029] In the process of adjustment, a corresponding variation of
the difference of amplitude is obtained by observing the track
crossing signal 20. When the moving trace is adjusted to approach
or pass through the center 14 of the base plate 13, the difference
of amplitude, "Am2", increases gradually to approach or equal to
the maximum value, "Am1". When the moving trace is moved away from
the center 14, the difference of amplitude, "Am2", decreases
gradually. Consequently, in the process of the adjustment, when the
maximum difference of amplitude, "Am2", appears, it means the
mechanical error of optical disc reading device is reduced to a
minimum. In the exemplary embodiment, the mechanical error is
adjusted for maximizing the difference of amplitude, "Am2", to a
maximum value, "Am1", or a maximum value of peak-to-peak without
mechanical error.
[0030] FIG. 4A and FIG. 4B are two schematic diagrams of track
crossing signal according to the present invention utilizing an
eccentric optical disc to examine the mechanical error of optical
disc reading device. As shown in FIG. 4A, there are two points "E"
and "F" of adjacent wave troughs on the wave envelope 22 defined by
wave peaks of the track crossing signal 20. And the two points
respectively correspond to two points of adjacent wave peaks on the
wave envelope 24 defined by wave troughs of the track crossing
signal 20. The difference of amplitude, "Am3" and "Am4", are
obviously different. That is to say, the eccentric error of the
optical disc and the mechanical error of optical disc reading
device make the adjacent difference of amplitude, "Am3" and "Am4",
very different. The track crossing signal 20 of this type is
observed more easily when the optical pickup 12 approaches to the
center 14.
[0031] As shown in FIG. 3C, the screws 17 adjust the position of
the guide bars 15 and make the moving trace to pass through the
center 14 of the base plate 13. During the process, since the
optical disc reading device 10 is examined using the eccentric
optical disc, from the track crossing signal 20, shown in FIG. 4B,
it is observed the difference of amplitude "Am3" and "Am4" are
almost equal. It means that the mechanical error of optical disc
reading device 10 is very small.
[0032] As described above, the present invention provides an
optical reading device capable of adjusting the mechanical error of
optical pickup. The optical reading device at least includes an
optical pickup, a base plate and guide bars. The base plate
includes a center and supports an optical disc. The guide bars
include an end terminal which defines a moving trace and guide the
optical pickup and optical disc to perform a relative movement on
the moving trace. The feature of the optical reading device
includes at least a screw which is disposed on the end terminal.
The guide bars are adjusted to make the moving trace passing
through the center by the screws.
[0033] In the foregoing specification the invention has been
described with reference to specific exemplar aspects thereof. It
will, however, be evident that various modification and changes may
be made thereto without departing from the broader spirit and scope
of the invention. The specification and drawings are, accordingly,
to be regarded in an illustrative rather than restrictive
sense.
* * * * *