Image forming apparatus which changes clock frequencies in accordance with recording sheet shrinkage
First Claim
1. An apparatus for forming a duplex image on a recording sheet, said duplex image including an obverse-side image formed on an obverse surface of said recording sheet and a reverse-side image formed on a reverse surface of said recording sheet, said apparatus comprising:
- an image-forming section to form said obverse-side image and said reverse-side image on a photoreceptor element by scanning a light beam onto said photoreceptor element, wherein the light beam is modulated with image signals based on pixel-clock signals and reflected from a polygon mirror rotating at an operating velocity based on polygon-clock signals;
a transferring section to transfer said obverse-side image and said reverse-side image formed on said photoreceptor element onto said obverse surface and said reverse surface of said recording sheet, respectively;
a fixing section to fix said obverse-side image and said reverse-side image onto said obverse surface and said reverse surface of said recording sheet, respectively; and
a clock-frequency changing section to automatically change (i) a pixel-clock frequency which is a frequency of said pixel-clock signals, and (ii) a polygon-clock frequency which is a frequency of said polygon-clock signals, in accordance with a degree of shrinkage of said recording sheet caused by a fixing operation performed in said fixing section, wherein the clock-frequency changing section changes the pixel-clock frequency and the polygon-clock frequency at a transition time which occurs at least one of;
(i) after said image-forming section completes an image-forming operation for said obverse-side image and before said image-forming section commences an image-forming operation for said reverse-side image, and (ii) after said image-forming section completes an image-forming operation for said reverse side image and before said image forming section commences an image-forming operation for said obverse-side image.
1 Assignment
0 Petitions
Accused Products
Abstract
There is described a duplex image-forming apparatus having a function of forming images onto both sides of a transfer material. The apparatus includes an image-forming section to respectively form an obverse-side image and a reverse-side image on a photoreceptor element by scanning a light beam, modulated with image signals based on pixel-clock signals and reflected from a polygon mirror rotating at an operating velocity based on polygon-clock signals; a transferring section to transfer said obverse-side image and said reverse-side image onto both surfaces of said recording sheet; a fixing section to fix the images onto both surfaces of said recording sheet; and a clock-frequency changing section to change a pixel-clock frequency, and a polygon-clock frequency, corresponding to a degree of shrinkage of said recording sheet caused by a fixing operation performed in said fixing section, at a transition time of an image-forming operation from one side to another side.
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Citations
13 Claims
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1. An apparatus for forming a duplex image on a recording sheet, said duplex image including an obverse-side image formed on an obverse surface of said recording sheet and a reverse-side image formed on a reverse surface of said recording sheet, said apparatus comprising:
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an image-forming section to form said obverse-side image and said reverse-side image on a photoreceptor element by scanning a light beam onto said photoreceptor element, wherein the light beam is modulated with image signals based on pixel-clock signals and reflected from a polygon mirror rotating at an operating velocity based on polygon-clock signals;
a transferring section to transfer said obverse-side image and said reverse-side image formed on said photoreceptor element onto said obverse surface and said reverse surface of said recording sheet, respectively;
a fixing section to fix said obverse-side image and said reverse-side image onto said obverse surface and said reverse surface of said recording sheet, respectively; and
a clock-frequency changing section to automatically change (i) a pixel-clock frequency which is a frequency of said pixel-clock signals, and (ii) a polygon-clock frequency which is a frequency of said polygon-clock signals, in accordance with a degree of shrinkage of said recording sheet caused by a fixing operation performed in said fixing section, wherein the clock-frequency changing section changes the pixel-clock frequency and the polygon-clock frequency at a transition time which occurs at least one of;
(i) after said image-forming section completes an image-forming operation for said obverse-side image and before said image-forming section commences an image-forming operation for said reverse-side image, and (ii) after said image-forming section completes an image-forming operation for said reverse side image and before said image forming section commences an image-forming operation for said obverse-side image. - View Dependent Claims (2, 3)
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4. An apparatus for forming a duplex color image on a recording sheet, said duplex color image including an obverse-side color image formed on an obverse surface of said recording sheet and a reverse-side color image formed on a reverse surface of said recording sheet, said apparatus comprising:
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a plurality of image-creating units, each of which corresponds to one of a plurality of colors and each of which forms a unicolor image by scanning a light beam to form said obverse-side color image and said reverse-side color image on a photoreceptor element, wherein the light beam is modulated with image signals based on pixel-clock signals and reflected from a polygon mirror rotating at an operating velocity based on polygon-clock signals;
a transferring section to transfer said obverse-side color image and said reverse-side color image formed on said photoreceptor element onto said obverse surface and said reverse surface of said recording sheet, respectively;
a fixing section to fix said obverse-side color image and said reverse-side color image onto said obverse surface and said reverse surface of said recording sheet, respectively; and
a clock-frequency changing section to automatically change (i) a pixel-clock frequency for each of said plurality of image-creating units which is a frequency of said pixel-clock signals, and (ii) a polygon-clock frequency for each of said plurality of image-creating units which is a frequency of said polygon-clock signals, in accordance with a degree of shrinkage of said recording sheet caused by a fixing operation performed in said fixing section, wherein the clock-frequency changing section changes the pixel-clock frequency and the polygon-clock frequency at a transition time which occurs at least one of;
(i) after said plurality of image-creating units complete image-forming operations for said obverse-side color image before said plurality of image-creating units commence image-forming operations for said reverse-side color image, and (ii) after said image-forming section completes image-forming operations for said reverse-side color image and before said image forming section commences image-forming operations for said obverse-side color image. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification