US4772919A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrophotographic copying machine
Assignee: Minolta Co Ltd
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Filing: 1986-09-05
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Granted: 1988-09-20
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Expires: 2006-09-05
Abstract
Abstract An electrophotographic copying machine adapted to provide a copied image for preparing a master plate for a thermal type stencil printing machine as well as a copied image for other, ordinary use. The copying machine includes an image forming device including a photosensitive member defining a photoconductive layer on a surface thereof, a charging device for charging the surface of the photosensitive member, an exposure device for illuminating an original image and forming on the photosensitive member an electrostatic latent image corresponding to the original image, and a developing device for causing a charged toner to electrostatically and selectively adhere to the electrostatic latent image on the photosensitive member. The copying machine further includes a transfer device for transferring the charged toner from the photosensitive member to copying paper, and an image density dropping device for selectively controlling the image forming device to cause a sharp drop in an image density on the copying paper with respect to a density of the original.
Inventors
- 👤 Tsugihito Yoshiyama
- 👤 Masataka Oda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:39
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/50; G03G15/02; G03G15/0266; G03G15/04; G03G15/043; G03G15/06; G03G15/065
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
88 words
An electrophotographic copying machine comprising: image forming means for forming on a photosensitive member an electrostatic latent image corresponding to an original to be copied and developing said electrostatic latent image into a toner image, transfer means for transferring said toner image corresponding to said electrostatic latent image onto copying paper, and image density dropping means for selectively controlling said image forming means to drop an image density on the copying paper to a density suitable for forming a master plate for a thermal type stencil printing machine.
Claim 2
Dependent Claim
88 words
An electrophotographic copying machine comprising: image forming means for forming on a photosensitive member an electrostatic latent image corresponding to an original to be copied and developing said electrostatic latent image into a toner image, transfer means for transferring said toner image corresponding to said electrostatic latent image onto copying paper, and image density dropping means for selectively controlling said image forming means to drop an image density on the copying paper to a density suitable for forming a master plate for a thermal type stencil printing machine.
Claim 3
Dependent Claim
133 words
An electrophotographic copying machine comprising: image forming means including a photosensitive member defining a photoconductive layer on a surface thereof, a charging device for charging the surface of said photosensitive member, an exposure device having an exposure lamp for illuminating an original image and forming on said photosensitive member an electrostatic latent image corresponding to said original image, and a developing device for causing a charged toner to electrostatically and selectively adhere to said electrostatic latent image on said photosensitive member, transfer means for transferring said charged toner adhering to said photosensitive member to copying paper, and image density dropping means for selectively controlling said image forming means to drop an image density on the copying paper to a density suitable for forming a master plate for a thermal type stencil printing machine.
Claim 4
Dependent Claim
133 words
An electrophotographic copying machine comprising: image forming means including a photosensitive member defining a photoconductive layer on a surface thereof, a charging device for charging the surface of said photosensitive member, an exposure device having an exposure lamp for illuminating an original image and forming on said photosensitive member an electrostatic latent image corresponding to said original image, and a developing device for causing a charged toner to electrostatically and selectively adhere to said electrostatic latent image on said photosensitive member, transfer means for transferring said charged toner adhering to said photosensitive member to copying paper, and image density dropping means for selectively controlling said image forming means to drop an image density on the copying paper to a density suitable for forming a master plate for a thermal type stencil printing machine.
Claim 5
Dependent Claim
38 words
An electrophotographic copying machine as claimed in claim 2 wherein said image density dropping means is operable to control said charging device to drop an amount of electric charge applied to said photosensitive member by said charging device.
Claim 6
Dependent Claim
45 words
An electrophotographic copying machine as claimed in claim 3 wherein said charging device comprises the scorotron type including a grid electrode grounded through two varistors connected thereto in series, and said image density dropping means comprises a bypass line for short-circuiting one of said varistors.
Claim 7
Dependent Claim
23 words
An electrophotographic copying machine as claimed in claim 4 wherein said image density dropping means includes switching means mounted on said bypass line.
Claim 8
Dependent Claim
31 words
An electrophotographic copying machine as claimed in claim 5 wherein said switching means comprises a relay, and said image density dropping means further includes an ON/OFF switch for actuating said relay.
Claim 9
Dependent Claim
30 words
An electrophotographic copying machine as claimed in claim 3 wherein said image density dropping means is operable to control said exposure device to weaken the illumination by said exposure lamp.
Claim 10
Dependent Claim
28 words
An electrophotographic copying machine as claimed in claim 7 wherein said image density dropping means is operable to control said developing device to shift a developing bias voltage.
Claim 11
Dependent Claim
42 words
An electrophotographic copying machine as claimed in claim 2 wherein said image density dropping means is operable to control said exposure device to shift the illumination by said exposure lamp thereby to drop an amount of electric charge for the photosensitive member.
Claim 12
Dependent Claim
28 words
An electrophotographic copying machine as claimed in claim 9 wherein said image density dropping means is operable to control said developing device to shift a developing bias voltage.
Claim 13
Dependent Claim
54 words
An electrophotographic copying machine as claimed in claim 9 wherein said exposure device includes a triac disposed between said exposure lamp and an AC source, and a phase angle control circuit for controlling said triac, and said image density dropping means comprises a circuit for shifting a voltage of said phase angle control circuit.
Claim 14
Dependent Claim
24 words
An electrophotographic copying machine as claimed in claim 11 wherein said image density dropping means includes switching means mounted on said voltage shifting circuit.
Claim 15
Dependent Claim
28 words
An electrophotographic copying machine as claimed in claim 2 wherein said image density dropping means is operable to control said developing device to shift a developing bias voltage.
Claim 16
Dependent Claim
117 words
An electrophotographic copying machine comprising: image forming means for forming an electrostatic latent image on a photosensitive member and developing said electrostatic latent image into a toner image, and image density dropping means for controlling said image forming means to drop an image density on copying paper to a density suitable for forming a master plate for a thermal type stencil printing machine, wherein said image forming means is adjusted to provide a density of a copied image of at least 1.1, and said image density dropping means is selectively operable to control said image forming means to drop the density of the copied image to be in a range of from about 0.4 to about 0.9.
Claim 17
Dependent Claim
117 words
An electrophotographic copying machine comprising: image forming means for forming an electrostatic latent image on a photosensitive member and developing said electrostatic latent image into a toner image, and image density dropping means for controlling said image forming means to drop an image density on copying paper to a density suitable for forming a master plate for a thermal type stencil printing machine, wherein said image forming means is adjusted to provide a density of a copied image of at least 1.1, and said image density dropping means is selectively operable to control said image forming means to drop the density of the copied image to be in a range of from about 0.4 to about 0.9.
Claim 18
Dependent Claim
185 words
An electrophotographic copying machine comprising: image forming means including a photosensitive member defining a photoconductive layer on a surface thereof, a charging device for charging the surface of said photosensitive member, an exposure device having an exposure lamp for illuminating an original image and forming on said photosensitive member an electrostatic latent image corresponding to said original image, and a developing device for causing charged toner to electrostatically and selectively adhere to said electrostatic latent image on said photosensitive member, transfer means for transferring said charged toner adhering to said photosensitive member to copying paper, and image density dropping means for controlling said image forming means to drop an image density on the copying paper to a density suitable for forming a master plate for a thermal type stencil printing machine, wherein said image forming means is adjusted to provide a density of a copied image of at least 1.1, and said image density dropping means is selectively operable to control said image forming means to drop the density of the copied image to be in a range of from about 0.4 to about 0.9.
Claim 19
Dependent Claim
185 words
An electrophotographic copying machine comprising: image forming means including a photosensitive member defining a photoconductive layer on a surface thereof, a charging device for charging the surface of said photosensitive member, an exposure device having an exposure lamp for illuminating an original image and forming on said photosensitive member an electrostatic latent image corresponding to said original image, and a developing device for causing charged toner to electrostatically and selectively adhere to said electrostatic latent image on said photosensitive member, transfer means for transferring said charged toner adhering to said photosensitive member to copying paper, and image density dropping means for controlling said image forming means to drop an image density on the copying paper to a density suitable for forming a master plate for a thermal type stencil printing machine, wherein said image forming means is adjusted to provide a density of a copied image of at least 1.1, and said image density dropping means is selectively operable to control said image forming means to drop the density of the copied image to be in a range of from about 0.4 to about 0.9.
Claim 20
Dependent Claim
38 words
An electrophotographic copying machine as claimed in claim 15 wherein said image density dropping means is operable to control said charging device to drop an amount of electric charge applied to said photosensitive member by said charging device.
Claim 21
Dependent Claim
68 words
An electrophotographic copying machine as claimed in claim 16 wherein said charging device comprises the scorotron type including a grid electrode grounded through two varistors connected thereto in series, and said image density dropping means comprises a bypass line for short-circuiting one of said varistors, and wherein said image density dropping means includes a relay mounted on said bypass line and an ON/OFF switch for actuating said relay.
Claim 22
Dependent Claim
30 words
An electrophotographic copying machine as claimed in claim 16 wherein said image density dropping means is operable to control said exposure device to weaken the illumination by said exposure lamp.
Claim 23
Dependent Claim
28 words
An electrophotographic copying machine as claimed in claim 18 wherein said image density dropping means is operable to control said developing device to shift a developing bias voltage.
Claim 24
Dependent Claim
42 words
An electrophotographic copying machine as claimed in claim 15 wherein said image density dropping means is operable to control said exposure device to shift the illumination by said exposure lamp thereby to drop an amount of electric charge for the photosensitive member.
Claim 25
Dependent Claim
54 words
An electrophotographic copying machine as claimed in claim 20 wherein said exposure device includes a triac disposed between said exposure lamp and an AC source, and a phase angle control circuit for controlling said triac, and said image density dropping means comprises a circuit for shifting a voltage of said phase angle control circuit.
Claim 26
Dependent Claim
28 words
An electrophotographic copying machine as claimed in claim 15 wherein said image density dropping means is operable to control said developing device to shift a developing bias voltage.
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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) | 1991-09-20 | 1992-03-21 | 1992-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-20 | 1996-03-21 | 1996-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-20 | 2000-03-21 | 2000-09-20 | $7700.00 | Window Closed / Lapsed |