US4914459A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Image forming apparatus
Assignee: Ricoh Co Ltd
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Filing: 1989-04-14
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Granted: 1990-04-03
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Expires: 2009-04-14
Abstract
Abstract An electrophotographic copier, facsimile machine, laser printer or similar image forming apparatus for reproducing an image on a paper sheet by transforming an image signal representative of the image into an image forming signal by pulse width modulation, causing a spot beam in the form of a laser beam which is modulated by the image forming signal to scan a photoconductive element to form an electrostatic latent image thereon, developing the latent image to render it visible, and transferring the visible image to a paper sheet. The laser beam output, the set pulse widths of the image forming signal (beam turn-on times) and the bias voltage for development are changed in association with the deterioration of the laser beam power and the sensitivity of the photoconductive element.
Inventors
- 👤 Takashi Mama
- 👤 Kenichirou Asada
- 👤 Takanobu Fujioka
- 👤 Yoshio Kaneko
- 👤 Masaaki Kogure
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:34
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/407; H04N1/4076; H04N1/4078; G; G03; G03G; G03G15/00; G03G15/06; G03G15/065; G03G15/50; G03G15/5033; G03G15/5037; G06; G06K; G06K15/00; G06K15/02; G06K15/12; G06K15/1204; G06K15/1209; G06K15/1214; H04N1/23; H04N1/29; H04N1/40025; H04N1/40037; H04N1/4005; G03G2215/00; G03G2215/00025; G03G2215/00029; G03G2215/00033; G03G2215/00037; G03G2215/00042; G03G2215/00054
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
98 words
An apparatus for forming an electrostatic latent image representative of image information and a visible image of said latent image on an image carrier by illuminating said image carrier by a spot beam which is manipulated by an image forming signal associated with said image information, said apparatus comprising: sensor means for sensing a condition of said image carrier and producing an output signal representative of the sensed condition; and illumination time changing means for changing a duration of illumination of said image carrier by the spot beam in response to the output signal of said sensor means.
Claim 2
Independent Claim
98 words
An apparatus for forming an electrostatic latent image representative of image information and a visible image of said latent image on an image carrier by illuminating said image carrier by a spot beam which is manipulated by an image forming signal associated with said image information, said apparatus comprising: sensor means for sensing a condition of said image carrier and producing an output signal representative of the sensed condition; and illumination time changing means for changing a duration of illumination of said image carrier by the spot beam in response to the output signal of said sensor means.
Claim 3
Dependent Claim
26 words
An apparatus as claimed in claim 1, wherein the spot beam comprises a laser beam issuing from a laser and modulated by the image forming signal.
Claim 4
Dependent Claim
38 words
An apparatus as claimed in claim 2, wherein said illumination time changing means comprises pulse width changing means for changing set pulse widths of the image forming signal in response to the output signal of said sensor means.
Claim 5
Dependent Claim
42 words
An apparatus as claimed in claim 3, wherein said sensor means comprises a surface potential sensor for sensing a surface potential of the latent image which is formed on said image carrier by causing the laser beam to scan said image carrier.
Claim 6
Dependent Claim
42 words
An apparatus as claimed in claim 3, wherein said sensor means comprises a reflection density sensor for sensing a reflection density of the visible image which is formed on said image carrier by causing the laser beam to scan said image carrier.
Claim 7
Dependent Claim
35 words
An apparatus as claimed in claim 3, further comprising laser beam output changing means for changing an output of the laser beam from said laser in response to the output signal of said sensor means.
Claim 8
Dependent Claim
25 words
An apparatus as claimed in claim 6, wherein said sensor means comprises a charge potential sensor for sensing a charge potential on said image carrier.
Claim 9
Dependent Claim
34 words
An apparatus as claimed in claim 6, wherein said sensor means comprises a reflection density sensor for detecting a density of a background area of the image which is formed on said image carrier.
Claim 10
Dependent Claim
52 words
An apparatus as claimed in claim 3, further comprising bias voltage applying means for applying a bias voltage for development to developing means which forms the visible image on said image carrier, and bias voltage changing means for changing the bias voltage in response to the output signal of said sensor means.
Claim 11
Dependent Claim
25 words
An apparatus as claimed in claim 9, wherein said sensor means comprises a charge potential sensor for sensing a charge potential on said image carrier.
Claim 12
Dependent Claim
33 words
An apparatus as claimed in claim 8, wherein said sensor means comprises a reflection density sensor for detecting a density of background area of the image which is formed on said image carrier.
References Cited (Backward Citations)
US4283785A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-02 | 1993-10-02 | 1994-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-02 | 1997-10-02 | 1998-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-02 | 2001-10-02 | 2002-04-03 | $7700.00 | Window Closed / Lapsed |