US5235584A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for detecting a position of a light spot on an optical disc
Assignee: Pioneer Corp
•
Filing: 1991-10-18
•
Granted: 1993-08-10
•
Expires: 2011-10-18
Abstract
Abstract An apparatus detects a position of a light spot necessary for the tracking control and the track jumping control at the time of reproducing an optical disk. Three light beams are used to provide three push-pull outputs from the respective light beams, thus making it possible to discriminate whether or not the light spot is in the on-track state on the basis of a value obtained as the result of a predetermined calculation of the respective push-pull outputs. In this apparatus, there is employed an arrangement such that in the case where the central light spot of the three light spots exists on the axis of one recording track, other two preceding and succeeding light spots are not projected onto the adjacent tracks.
Inventors
- 👤 Junichi Yoshio
- 👤 Sinichi Nagahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:23
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0901; G11B7/0903; G11B7/0943
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
426 words
An apparatus for detecting a position of a light spot on an optical disk, in which a reflected light beam from a signal recording surface of the optical disk is used to detect whether or not the light spot exists on a center line of a recording track axis of the optical disk, said apparatus comprising: light emitting means for emitting, onto said signal recording surface, a first light spot, a second light spot located at a position preceding to the first light spot with a first predetermined spacing in a direction of the recording track axis and with a second predetermined spacing in a direction perpendicular to the center line of the recording track, and a third light spot located at a position succeeding to the first light spot with the same spacing as the first predetermined spacing in a direction of the center line of the recording track and with the same spacing as the second predetermined spacing on the opposite side to the second light spot in a direction perpendicular to the center line of the recording track axis; first photodetection means including bisected detector surfaces, and for applying photoelectric conversion to a reflected light beam from the first light spot to output two electric signals; second photodetection means including bisected detector surfaces, and for applying photoelectric conversion to a reflected light beam from the second light spot to output two electric signals; third photodetection means including bisected detector surfaces and for applying photoelectric conversion to a reflected light beam from the third spot to output two electric signals; and operation means for calculating a first difference output indicative of a difference between the two electric signals from respective detector surfaces of said first photodetection means, a second difference output indicative of a difference between the two electric signals from respective detector surfaces of said second photodetection means, a third difference output indicative of a difference between the two electric signals from respective detector surfaces of the third photodetection means, and a fourth difference output including a low frequency band component of the third difference output obtained by eliminating any radio frequency signal component of the third difference output, said operation means calculating a sum of the second and the fourth difference outputs, calculating a product of said sum and a predetermined real number, calculating a difference between the product and the first difference output to output a first light spot position signal, and calculating a difference between the second and the fourth difference outputs to output a second light spot position signal.
Claim 2
Independent Claim
426 words
An apparatus for detecting a position of a light spot on an optical disk, in which a reflected light beam from a signal recording surface of the optical disk is used to detect whether or not the light spot exists on a center line of a recording track axis of the optical disk, said apparatus comprising: light emitting means for emitting, onto said signal recording surface, a first light spot, a second light spot located at a position preceding to the first light spot with a first predetermined spacing in a direction of the recording track axis and with a second predetermined spacing in a direction perpendicular to the center line of the recording track, and a third light spot located at a position succeeding to the first light spot with the same spacing as the first predetermined spacing in a direction of the center line of the recording track and with the same spacing as the second predetermined spacing on the opposite side to the second light spot in a direction perpendicular to the center line of the recording track axis; first photodetection means including bisected detector surfaces, and for applying photoelectric conversion to a reflected light beam from the first light spot to output two electric signals; second photodetection means including bisected detector surfaces, and for applying photoelectric conversion to a reflected light beam from the second light spot to output two electric signals; third photodetection means including bisected detector surfaces and for applying photoelectric conversion to a reflected light beam from the third spot to output two electric signals; and operation means for calculating a first difference output indicative of a difference between the two electric signals from respective detector surfaces of said first photodetection means, a second difference output indicative of a difference between the two electric signals from respective detector surfaces of said second photodetection means, a third difference output indicative of a difference between the two electric signals from respective detector surfaces of the third photodetection means, and a fourth difference output including a low frequency band component of the third difference output obtained by eliminating any radio frequency signal component of the third difference output, said operation means calculating a sum of the second and the fourth difference outputs, calculating a product of said sum and a predetermined real number, calculating a difference between the product and the first difference output to output a first light spot position signal, and calculating a difference between the second and the fourth difference outputs to output a second light spot position signal.
Claim 3
Dependent Claim
116 words
An apparatus for detecting a position of a light spot on an optical disk as set forth in claim 1, wherein in the case where a position of said first light spot on the recording track is in a non-recording state, after the time required until the light spot moves by a distance between the center of the first light spot and that of the third light spot has passed from the above time point when the position of the light spot is placed in the non-recording state, said operation means samples and holds the third difference output to generate the fourth difference output, thus to calculate the first and the second light spot position signals.
Claim 4
Dependent Claim
51 words
An apparatus for detecting a position of a light spot on an optical disk as set forth in claim 1, wherein said operation means holds a peak level of the third difference output to generate the fourth difference output, thus to calculate the first and the second light spot position signals.
Claim 5
Dependent Claim
58 words
An apparatus for detecting a position of a light spot on an optical disk as set forth in claim 1, wherein said operation means amplifies the low frequency band component of the third difference output at a predetermined amplification factor to generate the fourth difference output, thus to calculate the first and the second light spot position signals.
Claim 6
Dependent Claim
48 words
An apparatus for detecting a position of a light spot on an optical disk as set forth in claim 1, wherein said operation means comprises a low pass filter means for eliminating the radio frequency signal component of the third difference output to generate the fourth difference output.
References Cited (Backward Citations)
US5148424A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-08-09 | 1997-02-08 | 1997-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-09 | 2001-02-08 | 2001-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-09 | 2005-02-08 | 2005-08-10 | $7700.00 | Window Closed / Lapsed |