# US 5,349,374 A · Color image forming device to prevent color shifting

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- Number: US 5,349,374 A
- Document ID: US5349374A
- Status: Granted
- Kind: A
- Application number: 07/996,639
- Filed: 1992-12-24
- Granted: 1994-09-20
- Earliest claimed: 1991-12-30
- Assignees: Fuji Xerox Co., Ltd.
- Inventors: Kazuhiko Arai; Toru Teshigawara; Toshiaki Sagara
- Web page: https://patentgrep.com/patent/US5349374A

## CPC

- H04N 1/508: {using the same reproducing head for two or more colour components}
- H04N 1/0473: {in subscanning direction, e.g. picture start or line-to-line synchronisation}
- H04N 1/1135: {for the main-scan only}
- H04N 1/12: using the sheet-feed movement {or the medium-advance or the drum-rotation movement} as the slow scanning component, {e.g. arrangements for the main-scanning}({sheet-feed movement by translatory movement of a flat picture-bearing surface H04N1/1008; main-scanning using oscillating or rotating mirrors H04N1/113; } using multi-element arrays H04N1/19)
- H04N 2201/0471: using dedicated detectors
- H04N 2201/04722: on a photoconductive drum or belt
- H04N 2201/04732: Detecting at infrequent intervals, e.g. once or twice per line for main-scan control
- H04N 2201/04744: by detecting the scanned beam or a reference beam
- H04N 2201/04786: Controlling a start time, e.g. for output of a line of data (H04N2201/04784 takes precedence)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

Disclosed is a color image forming device in which latent images are formed by radiating a light beam onto a photoreceptor for each of colors, the latent images are developed to provide visible images, and a recording medium is transported to the visible images a plurality of times to form on the recording medium a color image consisting of a plurality of colors. The color image forming device includes a unit for detecting a reference transporting position of the recording medium to be moved to the photoreceptor, a unit for detecting a scan start signal of the light beam, a unit for measuring an error time from detection of the reference transporting position to detection of the scan start signal, and a unit for correcting a radiation timing of the light beam in accordance with the error time.

## Claims

### Claim 1

A color image forming device in which latent images are formed by radiating a light beam onto a photoreceptor for each of a plurality of colors, the latent images are developed to provide visible images, and a recording medium is transported to the visible images a plurality of times to thereby form a color image consisting of a plurality of colors on the recording medium, said color image forming device comprising:
means for detecting a reference transporting position of the recording medium to be moved to the photoreceptor;
means for detecting a scan start signal of the light beam;
means for measuring an error time from detection of the reference transporting position to detection of the scan start signal; and
means for correcting a radiation timing of the light beam in accordance with the error time.

### Claim 2 (depends on 1)

The color image forming device as set forth in claim 1, wherein said correcting means delays and corrects a detection timing of said reference transporting position in accordance with said error time.

### Claim 3 (depends on 1)

The color image forming device as set forth in claim 1, wherein said correcting means corrects a time from detection of said scan start signal to radiation of said light beam.

### Claim 4 (depends on 1)

The color image forming device as set forth in claim 1, wherein said correcting means corrects said radiation timing for at least one of said colors for latent images.

### Claim 5 (depends on 1)

The color image forming device as set forth in claim 1, wherein said recording medium includes an intermediate transfer member.