Claims
- 1. A tracking system for an optical memory disc having a plurality of recording tracks thereon including track address regions and track information regions, comprising:
- an optical head assembly including light beam producing means for producing a main light beam and two auxiliary light beams, said main and auxiliary light beams being scanned over said plurality of tracks;
- detector means for detecting light beams reflected from said tracks as a result of the scanning and producing a first tracking error signal in response to the light reflected from said main beam and a second tracking error signal in response to the light reflected from said two auxiliary beams; and
- tracking control means for performing tracking control of said main beam on one of said tracks in response to a first difference signal equal to a difference between said first tracking error signal and a second difference signal, said second difference signal representative of a difference between said first and second tracking error signal.
- 2. The tracking system defined in claim 1, wherein said tracking control means comprises:
- a first differential circuit providing said second difference signal;
- a low pass filter for obtaining a low frequency component of said second difference signal; and
- a second differential circuit having inputs coupled to receive said first tracking error signal and said low frequency component and an output providing said first difference signal.
Priority Claims (2)
Number |
Date |
Country |
Kind |
60-215695 |
Sep 1985 |
JPX |
|
60-245095 |
Oct 1985 |
JPX |
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Parent Case Info
This application is a divisional of application Ser. No. 08/074,147, filed on Jun. 9 1993 which ms a Continuation of application Ser. No. 07/804,639 filed on Dec. 11, 1991, abandoned, which is a Continuation of application Ser. No. 07/569,748 filed on Aug. 21, 1990, abandoned, which is a Continuation of application Ser. No. 07/232,850 filed on Aug. 16, 1988, abandoned, which is a Divisional application of application Ser. No. 06/911,410 filed on Sep. 25, 1986, now U.S. Pat. No. 4,787,076, the entire contents of which are hereby incorporated by reference.
US Referenced Citations (14)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2062901 |
May 1981 |
GBX |
Non-Patent Literature Citations (4)
Entry |
Patent Abstracts of Japan, vol. 8, No. 237, (p-310), Oct. 30, 1984, & JP59-112442. |
Patent Abstracts of Japan, vol. 8, No. 144, (p-284), Jul. 05, 1984, & JP59-42673. |
Patent Abstracts of Japan, vol. 9, No. 243, (p-392), Sep. 30, 1985, & JP60-95736. |
Patent Abstracts of Japan, vol. 9, No. 327, (p-415), Dec. 21, 1985, & JP60-151846. |
Divisions (2)
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Number |
Date |
Country |
Parent |
74147 |
Jun 1993 |
|
Parent |
911410 |
Sep 1986 |
|
Continuations (3)
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Number |
Date |
Country |
Parent |
804639 |
Dec 1991 |
|
Parent |
569748 |
Aug 1990 |
|
Parent |
232850 |
Aug 1988 |
|