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US4718068A
Expired / Lapsed
US
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Stabilized laser device of optical information recording/reproduction apparatus
Assignee: Olympus Corp
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Filing: 1985-12-30
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Granted: 1988-01-05
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Expires: 2005-12-30
Abstract
Abstract In a stabilized laser device of an optical recording/reproduction apparatus, in the reproduction mode, a laser beam of reproduction level is radiated on an optical disk, and data is read from the disk in the form of the light reflected from the disk. In the recording mode, a laser beam of the recording level (several times higher than the reproduction level) is radiated on the disk to form pits in the disk surface. The device has a semiconductor laser, a reference voltage generation source for generating reference values of the reproduction and recording levels, and a photodiode for photoelectrically converting laser light from the semiconductor laser so as to generate a detection signal a source of drive signals is provided for generating a first drive signal corresponding to the difference between the reference value of the recording level and the detection signal from the photodiode, and a second drive signal corresponding to the difference between the sum of reference values of the recording and reproduction levels and the detection signal from the photodiode. A switch supplies, in the reproduction mode, the first drive signal to the semiconductor laser and, in the recording mode, supplies one of the first drive signal and the sum of first and second drive signals in accordance with recording data.
Inventors
- 👤 Shozi Yoshikawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:41
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/125; G11B7/126; G11B19/00; G11B19/02
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
187 words
A stabilized laser device of an optical information recording/reproduction apparatus, comprising: laser means; setting means for setting first and second reference signals; photodetecting means for photoelectrically converting laser light emitted from said laser means and for generating a detection signal; first signal generating means for generating, during a reproduction mode, a first signal corresponding to a difference between the first reference signal and the detection signal from said photodetecting means; memory means for storing the first signal during a recording mode; second signal generating means for generating, during a recording mode, a second signal corresponding to a difference between the detection signal from said photodetecting means and a sum of the first and second reference signals; and switching means for supplying to said laser means, in a reproduction mode, a first drive signal corresponding to the first signal generated from said first signal generating means and for supplying, in a recording mode, to said laser means selectively varied in accordance with recording data a second drive signal corresponding to the first signal stored in said means and the second signal generated from said second signal generating means.
Claim 2
Dependent Claim
187 words
A stabilized laser device of an optical information recording/reproduction apparatus, comprising: laser means; setting means for setting first and second reference signals; photodetecting means for photoelectrically converting laser light emitted from said laser means and for generating a detection signal; first signal generating means for generating, during a reproduction mode, a first signal corresponding to a difference between the first reference signal and the detection signal from said photodetecting means; memory means for storing the first signal during a recording mode; second signal generating means for generating, during a recording mode, a second signal corresponding to a difference between the detection signal from said photodetecting means and a sum of the first and second reference signals; and switching means for supplying to said laser means, in a reproduction mode, a first drive signal corresponding to the first signal generated from said first signal generating means and for supplying, in a recording mode, to said laser means selectively varied in accordance with recording data a second drive signal corresponding to the first signal stored in said means and the second signal generated from said second signal generating means.
Claim 3
Dependent Claim
26 words
A stabilized laser device according to claim 1, in which said setting means comprises multiplier means for multiplying said second reference signal and the recording data.
Claim 4
Dependent Claim
33 words
A stabilized laser device according to claim 2, in which said setting means comprises a low-pass filter having its input coupled to said recording data and its output coupled to said multiplier means.
Claim 5
Dependent Claim
27 words
A stabilized laser device according to claim 2, in which said multiplier means comprises an analog switch to the gate of which said recording data is supplied.
Claim 6
Dependent Claim
28 words
A stabilized laser device according to claim 2, in which said multiplier means comprises an open collector transistor to the base of which said recording data is supplied.
Claim 7
Dependent Claim
27 words
A stabilized laser device according to claim 2, in which said multiplier means comprises a CMOS gate to the gate of which said recording data is supplied.
Claim 8
Dependent Claim
38 words
A stabilized laser device according to claim 1, wherein said switching means, in the recording mode, supplies said second drive signal to the laser means to be always at least equal in magnitude to the first drive signal.
Claim 9
Dependent Claim
40 words
A stabilized laser device according to claim 1, wherein said switching means varies the second drive signal by selectively supplying, in response to the recording data, a component corresponding to the second signal generated by the second signal generating means.
Claim 10
Dependent Claim
128 words
A stabilized laser device according to claim 1, wherein said first signal generating means comprises: a differential amplifier having one input terminal coupled to the photodetecting means to receive the detection signal and another input terminal coupled to the setting means to receive the first reference signal, a window comparator means for comparing the output from said diffrential amplifier with positive and negative threshold values to alternately generate first and second control signals when the positive and negative thresholds, respectively, are exceeded; a first up/down counter means for, in the production mode, alternately counting up and down in accordance with the first and second control signals, respectively; and a first D/A converter means for generating said first signal in accordance with the output from said first up/down counter.
Claim 11
Dependent Claim
83 words
A stabilized laser device according to claim 9, wherein said second signal generating means comprises: said differential amplifier; a third input terminal in said differential amplifier coupled to the setting means to receive the second reference signal; a second up/down counter means for, in the recording mode, alternately counting up and down in accordance with the first and second control signals, respectively; and a second D/A converter means for generating said second signal in acordance with the output from said second up/down counter.
References Cited (Backward Citations)
US3898583A
Cited
US4525822A
Cited
JPS58158051A
Cited
US4580044A
Cited
DE3404441A1
Cited
US4577320A
Cited
DE3541002A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-01-04 | 1991-07-06 | 1992-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-04 | 1995-07-06 | 1996-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-04 | 1999-07-06 | 2000-01-05 | $7700.00 | Window Closed / Lapsed |