EP0089021A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Overlay recording prevention device for optical disc apparatus
Assignee: Toshiba Corp
•
Filing: 1983-03-10
•
Granted: —
•
Expires: 2003-03-10
Abstract
Abstract An overlay recording prevention device for an optical disc apparatus detects a signal corresponding to a recording pit of a recorded track. This signal is detected from a photoelectric signal of an optical head (13) when a tracking error occurs in the recording mode and a beam spot is shifted onto an already-recorded track. A high-level recording laser beam is stopped in response to this detection signal.
Inventors
- 👤 Tsuneshi Yokota
- 👤 Akira Nakagawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 12:13
CPC Classifications
G; G11; G11B; G11B19/00; G11B19/02; G11B19/04; G11B27/00; G11B27/36; G11B7/00; G11B7/004; G11B7/0045
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
148 words
An overlay recording prevention device for an optical disc apparatus having an optical head (13) which has means (14) for selectively radiating an optical disc (11) with a low-level reproducing light beam and a high-level recording light beam for forming pits corresponding to recording data on said optical disc (11) and means (20) for converting reflected light from the optical disc into a photoelectric signal, comprising: tracking signal component detecting means (22, 23, 25) for detecting a tracking signal component in the photoelectric signal obtained by said optical head (13) in a recording mode; level variation detecting means (24) for detecting a variation in level of the tracking signal component due to the reflected light from the pits already formed on the optical disc; and stopping means (26) for stopping generation of the high-level recording beam in response to a detection signal from said level variation detecting means.
Claim 2
Dependent Claim
148 words
An overlay recording prevention device for an optical disc apparatus having an optical head (13) which has means (14) for selectively radiating an optical disc (11) with a low-level reproducing light beam and a high-level recording light beam for forming pits corresponding to recording data on said optical disc (11) and means (20) for converting reflected light from the optical disc into a photoelectric signal, comprising: tracking signal component detecting means (22, 23, 25) for detecting a tracking signal component in the photoelectric signal obtained by said optical head (13) in a recording mode; level variation detecting means (24) for detecting a variation in level of the tracking signal component due to the reflected light from the pits already formed on the optical disc; and stopping means (26) for stopping generation of the high-level recording beam in response to a detection signal from said level variation detecting means.
Claim 3
Dependent Claim
53 words
A device according to claim 1, wherein said tracking signal component detecting means includes: mask signal generating means (25) for generating a mask signal in synchronism with recording data; and a sample-and-hold circuit (22) for sampling and holding the photoelectric signal in synchronism with the mask signal from said mask signal generating means.
Claim 4
Dependent Claim
64 words
A device according to claim 1, wherein said level variation detecting means includes: an envelope detector (23) for enveloping an output signal from said tracking signal component detecting means and for producing an enveloped signal; and comparing means (24) for comparing the enveloped signal from said envelope detector (23) and a signal having a predetermined level and for producing an overlay recording prevention signal.
Claim 5
Dependent Claim
32 words
A device according to claim 1, wherein said stopping means comprises means (26) for interrupting transfer of the recording data in response to the detection signal from said level variation detecting means.
Claim 6
Dependent Claim
14 words
A device according to claim 1, wherein the light beam comprises a laser beam.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.