US4728989A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic latent image forming apparatus using semiconductor laser
Assignee: Minolta Co Ltd
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Filing: 1987-02-11
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Granted: 1988-03-01
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Expires: 2007-02-11
Abstract
Abstract An electrostatic latent image forming apparatus using a semiconductor laser 11 forms an image on a surface of a photoreceptor drum 15 by a laser beam modulated by an image signal while intensity of the laser beam is lowered by a reflection mirror 16 having a reflectance as low as 30%. The semiconductor laser 11 is driven by current obtained by adding bias current Iba to switching current Isw and a bias component out of an optical output level thereof is decreased by the reflection mirror 16 having the low reflectance. Therefore, an off-level optical output correponding to the bias current becomes lower than that in the case in which lowering of the intensity of the beam is not caused, and as a result, a "fogging" phenomenon or the like can be effectively prevented.
Inventors
- 👤 Naoto Ohmori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 03:37
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/024; H04N1/032; H04N1/036; H04N1/40; H04N1/40025; H04N1/40037
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
143 words
An electrostatic latent image forming apparatus comprising: a semiconductor laser, drive means for adding bias current to switching current modulated by an image signal and applying the current obtained of the addition to said semiconductor laser, thereby to excite said semiconductor laser to emit a laser beam, a photoreceptor having a surface on which an electrostatic latent image is to be formed by said laser beam, a scanning optical system for scanning said surface of said photoreceptor by said laser beam emitted from said semiconductor laser and forming an image by said laser beam on said surface of said photoreceptor, and optical means disposed in a path of transmission of said laser beam extending from said semiconductor laser to said photoreceptor for lowering intensity of said laser beam, thereby to decrease a component corresponding to said bias current out of said laser beam.
Claim 2
Dependent Claim
143 words
An electrostatic latent image forming apparatus comprising: a semiconductor laser, drive means for adding bias current to switching current modulated by an image signal and applying the current obtained of the addition to said semiconductor laser, thereby to excite said semiconductor laser to emit a laser beam, a photoreceptor having a surface on which an electrostatic latent image is to be formed by said laser beam, a scanning optical system for scanning said surface of said photoreceptor by said laser beam emitted from said semiconductor laser and forming an image by said laser beam on said surface of said photoreceptor, and optical means disposed in a path of transmission of said laser beam extending from said semiconductor laser to said photoreceptor for lowering intensity of said laser beam, thereby to decrease a component corresponding to said bias current out of said laser beam.
Claim 3
Dependent Claim
22 words
An electrostatic latent image forming apparatus in accordance with claim 1, wherein said optical means is a mirror having a low reflectance.
Claim 4
Dependent Claim
30 words
An electrostatic latent image forming apparatus in accordance with claim 2, wherein said mirror having the low reflectance is disposed to bend said path of transmission of said laser beam.
Claim 5
Dependent Claim
25 words
An electrostatic latent image forming apparatus in accordance with claim 3, wherein the reflectance of said mirror is in a range from 20 to 60%.
Claim 6
Dependent Claim
24 words
An electrostatic latent image forming apparatus in accordance with claim 1, wherein said optical means is a neutral density filter having a low transmittance.
Claim 7
Dependent Claim
25 words
An electrostatic latent image forming apparatus in accordance with claim 5, wherein the transmittance of said filter is in a range from 20 to 60%.
Claim 8
Dependent Claim
44 words
An electrostatic latent image forming apparatus in accordance with claim 1, wherein said drive means comprises: a switching portion for generating switching current in response to said image signal, and a bias portion for generating bias current to be added to said switching current.
Claim 9
Dependent Claim
51 words
An electrostatic latent image forming apparatus in accordance with claim 7, wherein said bias portion comprises: a light receiving element for receiving the laser beam emitted from said semiconductor laser, and an automatic power control circuit for controlling said bias current according to the beam received by said light receiving element.
Claim 10
Dependent Claim
104 words
An improved electrostatic latent image forming apparatus comprising: laser means for providing a laser beam; drive means for exciting the laser means to emit a laser beam capable of forming a latent image; means for compensating for the effect of any temperature variations on the output of the laser beam; a photoreceptor for forming the latent image from the impact of the laser beam, and means for lowering the intensity of the laser beam to decrese at least that portion of the laser beam intensity output that was emitted relative to any increase in the laser output resulting from the means for temperature compensation.
Claim 11
Dependent Claim
104 words
An improved electrostatic latent image forming apparatus comprising: laser means for providing a laser beam; drive means for exciting the laser means to emit a laser beam capable of forming a latent image; means for compensating for the effect of any temperature variations on the output of the laser beam; a photoreceptor for forming the latent image from the impact of the laser beam, and means for lowering the intensity of the laser beam to decrese at least that portion of the laser beam intensity output that was emitted relative to any increase in the laser output resulting from the means for temperature compensation.
Claim 12
Dependent Claim
26 words
The apparatus of claim 9 wherein the means for compensating for temperature variations increases a driving current to the laser means for providing a laser beam.
Claim 13
Dependent Claim
35 words
The apparatus of claim 9 wherein the means for lowering the intensity of the laser beam includes an optical member having a transmission range of 60 to 20 percent of the incident laser beam intensity.
Claim 14
Dependent Claim
24 words
The appartus of claim 11 wherein the optical member is a mirror with low reflectance in the path of transmission of the laser beam.
Claim 15
Dependent Claim
14 words
The apparatus of claim 11 wherein the optical member is a neutral density filter.
Claim 16
Dependent Claim
156 words
An improved electrostatic latent image forming apparatus comprising: means for providing a laser beam; means for providing an image signal; drive means for adding bias current to a switching current modulated by the image signal and applying the current obtained by the addition to the laser means, thereby to excite the laser to emit the laser beam; a photoreceptor having a surface on which an electrostatic latent image is to be formed by the laser beam; an optical system for impacting the surface of the photoreceptor by the laser beam emitted from the laser means and forming an image by the laser beam on the surface of the photoreceptor, and optical means disposed in a path of transmission of the laser beam extending from the laser means to the photoreceptor for lowering the intensity of the laser beam, thereby to decrease a component of laser energy corresponding to the laser energy produced by the bias current.
Claim 17
Dependent Claim
156 words
An improved electrostatic latent image forming apparatus comprising: means for providing a laser beam; means for providing an image signal; drive means for adding bias current to a switching current modulated by the image signal and applying the current obtained by the addition to the laser means, thereby to excite the laser to emit the laser beam; a photoreceptor having a surface on which an electrostatic latent image is to be formed by the laser beam; an optical system for impacting the surface of the photoreceptor by the laser beam emitted from the laser means and forming an image by the laser beam on the surface of the photoreceptor, and optical means disposed in a path of transmission of the laser beam extending from the laser means to the photoreceptor for lowering the intensity of the laser beam, thereby to decrease a component of laser energy corresponding to the laser energy produced by the bias current.
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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) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |