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Patent US4849980A successfully refreshed from Google Patents.
US4849980A
Expired / Lapsed
US
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Laser beam recording method and apparatus
Assignee: Fujifilm Holdings Corp
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Filing: 1987-12-23
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Granted: 1989-07-18
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Expires: 2007-12-23
Abstract
Abstract A laser beam recording method and apparatus are constituted for recording an image by obtaining a laser beam whose optical intensity is modulated by controlling a drive current for a semiconductor laser on the basis of a light emission level instructing signal corresponding to an image signal, and scanning the laser beam on a photosensitive material. The optical output is stabilized by detecting the optical intensity of the laser beam and feeding back a feedback signal corresponding to the detected optical intensity to the light emission level instructing signal. A filter circuit formed so that the gain gradually increases from near to a cutoff frequency of a circuit for the optical output stabilization toward a higher frequency side is disposed in a stage prior to the circuit for the optical output stabilization. Or, a bias current of a value smaller than the value of the drive current that produces the laser beam of the minimum optical intensity capable of exciting the photosensitive material is always fed to the semiconductor laser.
Inventors
- 👤 Takashi Shoji
- 👤 Takenori Tomita
- 👤 Hideo Watanabe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:29
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40025; H04N1/40037; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683; H01S5/06832; H04N1/4005; H01S5/0617; H01S5/06812
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
135 words
A laser beam recording method which comprises the following steps, in the course of obtaining a laser beam whose optical intensity is modulated by controlling a drive current for a semiconductor laser on the basis of a light emission level instructing signal corresponding to an image signal, and recording an image on a photosensitive material by scanning the laser beam on the photosensitive material: (i) stabilizing an optical output of said semiconductor laser by detecting the optical intensity of said laser beam and feeding back a feedback signal corresponding to the detected optical intensity to said light emission level instructing signal, and (ii) gradually increasing a gain in a stage prior to the stage for said optical output stabilization from near to a cutoff frequency in said optical output stabilization toward a higher frequency side.
Claim 2
Dependent Claim
135 words
A laser beam recording method which comprises the following steps, in the course of obtaining a laser beam whose optical intensity is modulated by controlling a drive current for a semiconductor laser on the basis of a light emission level instructing signal corresponding to an image signal, and recording an image on a photosensitive material by scanning the laser beam on the photosensitive material: (i) stabilizing an optical output of said semiconductor laser by detecting the optical intensity of said laser beam and feeding back a feedback signal corresponding to the detected optical intensity to said light emission level instructing signal, and (ii) gradually increasing a gain in a stage prior to the stage for said optical output stabilization from near to a cutoff frequency in said optical output stabilization toward a higher frequency side.
Claim 3
Dependent Claim
22 words
A method as defined in claim 1 wherein said gradual increase of said gain is effected by use of a filter circuit.
Claim 4
Dependent Claim
15 words
A method as defined in claim 2 wherein said filter circuit is a lead-lag filter.
Claim 5
Dependent Claim
174 words
A laser beam recording apparatus provided with a semiconductor laser for emitting a laser beam, a beam scanning system for scanning the laser beam on a photosensitive material, and a laser operation control circuit for producing a light emission level instructing signal corresponding to an image signal, and controlling a drive current for the semiconductor laser on the basis of the light emission level instructing signal, thereby to modulate the optical intensity of the laser beam, wherein the improvement comprises providing said laser operation control circuit with: (i) an optical output stabilizing circuit for detecting the optical intensity of said laser beam, and feeding back a feedback signal corresponding to the detected optical intensity to said light emission level instructing signal, and (ii) a filter circuit disposed to allow the passage of said light emission level instructing signal therethrough in a stage prior to said optical output stabilizing circuit, and formed so that the gain gradually increases from near to a cutoff frequency of said optical output stabilizing circuit toward a higher frequency side.
Claim 6
Dependent Claim
174 words
A laser beam recording apparatus provided with a semiconductor laser for emitting a laser beam, a beam scanning system for scanning the laser beam on a photosensitive material, and a laser operation control circuit for producing a light emission level instructing signal corresponding to an image signal, and controlling a drive current for the semiconductor laser on the basis of the light emission level instructing signal, thereby to modulate the optical intensity of the laser beam, wherein the improvement comprises providing said laser operation control circuit with: (i) an optical output stabilizing circuit for detecting the optical intensity of said laser beam, and feeding back a feedback signal corresponding to the detected optical intensity to said light emission level instructing signal, and (ii) a filter circuit disposed to allow the passage of said light emission level instructing signal therethrough in a stage prior to said optical output stabilizing circuit, and formed so that the gain gradually increases from near to a cutoff frequency of said optical output stabilizing circuit toward a higher frequency side.
Claim 7
Dependent Claim
15 words
An apparatus as defined in claim 4 wherein said filter circuit is a lead-lag filter.
Claim 8
Dependent Claim
193 words
A lser beam recording method which comprises the following steps, in the course of obtaining a laser beam whose optical intensity is modulated by controlling a drive current for a semiconductor laser on the basis of a light emission level instructing signal corresponding to an image signal, and recording an image on a photosensitive material by scanning the laser beam on the photosensitive material: (i) stabilizing an optical output of said semiconductor laser by detecting the optical intensity of said laser beam and feeding back a feedback signal corresponding to the detected optical intensity to said light emission level instructing signal, and (ii) always feeding a bias current of a value smaller than the value of said drive current, that produces said laser beam of the minimum optical intensity capable of exciting said photosensitive material, to said semiconductor laser, wherein said feeding of said bias current to said semiconductor laser is effected by adjustment of a correction table which provides predetermined density value for image density values of said image on said photosensitive material for correcting said image signal wherein said adjustment is carried out based on the optical density of said image.
Claim 9
Dependent Claim
193 words
A lser beam recording method which comprises the following steps, in the course of obtaining a laser beam whose optical intensity is modulated by controlling a drive current for a semiconductor laser on the basis of a light emission level instructing signal corresponding to an image signal, and recording an image on a photosensitive material by scanning the laser beam on the photosensitive material: (i) stabilizing an optical output of said semiconductor laser by detecting the optical intensity of said laser beam and feeding back a feedback signal corresponding to the detected optical intensity to said light emission level instructing signal, and (ii) always feeding a bias current of a value smaller than the value of said drive current, that produces said laser beam of the minimum optical intensity capable of exciting said photosensitive material, to said semiconductor laser, wherein said feeding of said bias current to said semiconductor laser is effected by adjustment of a correction table which provides predetermined density value for image density values of said image on said photosensitive material for correcting said image signal wherein said adjustment is carried out based on the optical density of said image.
Claim 10
Dependent Claim
35 words
A method as defined in claim 6 wherein said feeding of said bias current to said semiconductor laser is effected by a bias current feed circuit connected to a stage prior to said semiconductor laser.
Claim 11
Dependent Claim
182 words
A laser beam recording apparatus provided with a semiconductor laser for emitting a laser beam, a beam scanning system for scanning the laser beam on a photosensitive material, and a laser operation control circuit for producing a light emission level instructing signal corresponding to an image signal, and controlling a drive current for the semiconductor laser on the basis of a light emission level instructing signal thereby to modulate the optical intensity of the laser beam, wherein the improvement comprises providing said laser operation control circuit with: (i) an optical output stabilizing circuit for detecting the optical intensity of said laser beam, and feeding back a feedback signal corresponding to the detected optical intensity to said light emission level instructing signal, and (ii) a bias current feed means for always feeding a bias current of a value smaller than the value of said drive current, that produces said laser beam of the minimum optical intensity capable of exciting said photosensitive material, to said semiconductor laser, wherein said bias current feed means is constituted by a correction table for correcting said image signal.
Claim 12
Dependent Claim
182 words
A laser beam recording apparatus provided with a semiconductor laser for emitting a laser beam, a beam scanning system for scanning the laser beam on a photosensitive material, and a laser operation control circuit for producing a light emission level instructing signal corresponding to an image signal, and controlling a drive current for the semiconductor laser on the basis of a light emission level instructing signal thereby to modulate the optical intensity of the laser beam, wherein the improvement comprises providing said laser operation control circuit with: (i) an optical output stabilizing circuit for detecting the optical intensity of said laser beam, and feeding back a feedback signal corresponding to the detected optical intensity to said light emission level instructing signal, and (ii) a bias current feed means for always feeding a bias current of a value smaller than the value of said drive current, that produces said laser beam of the minimum optical intensity capable of exciting said photosensitive material, to said semiconductor laser, wherein said bias current feed means is constituted by a correction table for correcting said image signal.
Claim 13
Dependent Claim
28 words
An apparatus as defined in claim 8 wherein said bias current feed means is a bias current feed circuit connected to a stage prior to said semiconductor laser.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-07-17 | 1993-01-16 | 1993-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-07-17 | 1997-01-16 | 1997-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-07-17 | 2001-01-16 | 2001-07-18 | $7700.00 | Window Closed / Lapsed |