JPH04230774A - Color image forming device - Google Patents

Abstract

PURPOSE:To provide the color image forming device carrying out a bright color recording of high definition without color slippage. CONSTITUTION:The device is provided with a multiple number of photosensitive drums 101, 102, and 103, a polygon mirror 5 scanning with a multiple number of laser beams, and optical systems 6, 107, and 108. When an image of three primary colors formed by the photosensitive drum 101 to 103 are transferred to the recording paper 20, a reference mark is recorded on the recording paper in the transferring of the first color or before it, and by transferring the remaining colors based on the positional detection of this reference mark, the color image without color slippage can be formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording a plurality of images on recording paper in a superimposed manner.

0002

[Prior Art] Conventionally, such an image recording method includes a multicolor image recording method, particularly a method in which an electrostatic recording process for each color of an original is sequentially performed on recording paper while aligning each color (registration). Are known.

0003

[Problem to be Solved by the Invention] As a device for recording such multicolor images, a laser for full color (referring to a device that handles all kinds of natural colors as opposed to a limited type of color, that is, false color) is used. Color electrophotographic copying machines are known. Such a copying machine is shown in Figure 1.
A photosensitive drum 1 is provided as shown in FIG. is irradiated through the lens 6. After the photosensitive drum 1 is cleaned with a cleaner blade 15, the entire surface of the photosensitive drum 1 is charged by a primary charger 14, and then the charge is removed according to the above-mentioned image light beam, and an electrostatic latent image corresponding to the image is formed. This electrostatic latent image is created by the three primary colors of the input light: red (R), green (G), and blue (
Cyan (C), magenta (
Each color is developed by a development station that performs toner development for M) and yellow (Y). Numerals 8, 9, and 10 are developing rollers for developing yellow, magenta, and cyan colors, respectively, and 18 is a developing cover.

On the other hand, recording paper 20 stored in a recording paper storage box 11 is wound around a transfer drum 7 via a paper feed roller 12 and a guide 19, and the image developed for each color is transferred to a transfer charger 13. After being transferred to the recording paper 20 via the recording paper 20, the image is discharged onto the tray 17 via the paper discharge roller 16. In this case, the recording paper 20 is held by a holder (not shown) on the transfer drum 7, and the image is transferred to the same image position three times for each color. These three transfers must be accurately aligned to avoid misalignment, but registration may occur due to uneven rotation of the transfer drum and photosensitive drum, as well as expansion and contraction of the recording paper held on the transfer drum or poor retention. defects occur. This defect can be improved mechanically to some extent, but in order to record digital images with high precision with a dot configuration of 100 lines/inch (4 lines/mm) or more, it is necessary to diameter to 5
Taking into consideration the fact that the size must be reduced to about 0 μm or less and the pitch between each dot must be recorded in units of several μm, the mechanical improvement described above would result in a positional deviation of at most about 0.1 mm. can only be corrected.

Therefore, the object of the present invention is to eliminate the above-mentioned conventional drawbacks, eliminate color shift on recording paper in the multicolor recording process, and create a multicolor image that can record a clear, high-quality multicolor image that is faithful to the original. An object of the present invention is to provide a recording alignment method.

[0006]

[Means for Solving the Problems] The present invention is characterized in that a reference mark is added to the recording paper when recording the first color, and the recording position for the next color is controlled in accordance with this reference mark. It is.

[0007]

[Operation] By recording reference marks and aligning multicolor recording, a high-quality color image without color shift can be formed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows a laser beam printer suitable for using the method of the present invention, and this printer uses a yellow photosensitive drum 101, a magenta photosensitive drum 102, and a cyan photosensitive drum 103. An array laser 22 that generates three laser beams is used, and the laser beams generated by this laser are modulated via a laser modulator 3 for each of the three primary colors of the original.
It passes through an expander 4, is deflected by a polygon mirror 5, and is directed toward the photosensitive drum via a lens 6. The modulated light beam corresponding to the blue image is reflected by the mirror 107 and formed into an image on the yellow photosensitive drum 101, the modulated light beam corresponding to the green image is directly focused on the magenta photosensitive drum 102, and the modulated light beam corresponding to the red image is reflected by the mirror 108. , and are respectively imaged on the photosensitive drum 103 for cyan.

Each photosensitive drum 101, 102, 103 is provided with cleaner plates 110, 112, 114 and primary chargers 109, 111, 113, respectively, for cleaning the previous charging record and removing toner, and for cleaning the photosensitive drum. Charge the entire surface uniformly. Further, each drum is provided with a developing roller 104, 105, 106 corresponding to the color, and each roller is protected by a developing cover 130, 129, 128. Further, transfer chargers 127, 126, and 125 are arranged below each drum, and the recording paper storage box 11
The recording paper 20 stored in the is conveyed via the paper feed roller 12 and between each photosensitive drum and the charger via the paper conveyance rollers 120 and 121, passes through the static eliminator 122, and is transferred to the fixing roller 123.
, 124, and then discharged in the direction of the arrow.

In the above configuration, the laser beam modulated by the laser modulator 3 for the blue color of the original is deflected by the polygon mirror 5 and then sent to the lens 6 and the mirror 1.
07, an image is formed on the yellow photosensitive drum 101 charged by the primary charger 109, and an electrostatic latent image corresponding to the blue color of the original is formed. The image thus formed is developed by the developing roller 104, transferred to the recording paper 20 via the transfer charger 127, and recorded. In this case, reference marks (referred to as registration marks in printing terminology) 201 are added at two locations at the leading edge in the running direction of the margin W of the recorded image P by appropriate means as shown in FIG. 3(a). This can be added, for example, by forming it on the photosensitive drum 101 during electrostatic latent image formation, or by recording it on the recording paper 20 from outside during transfer.

The reference mark added in this way is detected by a detection device (not shown) such as a photocoupler before recording the next color, that is, magenta color, and the reference mark is detected by a detection device (not shown) such as a photocoupler, and the reference line or reference line width X shown in FIG. 3(a) is detected. is calculated. The recording positions of the next colors, magenta and cyan, are aligned according to this width. That is, laser modulation for green and red is synchronized according to the calculated reference line width. By doing this, the registration of each color can be made to match the image P for the first color on the recording paper. The reference mark mentioned above is shown in FIG. 3(b),
Marks 202 each having a shape as shown in FIG.
203. The example illustrated in FIG. 3(d) is that the tape 20 is used instead of the fiducial mark when recording the first color.
4 on the recording paper 20 after transferring or fixing the final color.
It is something that can be removed.

Furthermore, as shown in FIG. 4, a hole 401 is provided at the reference position of the recording paper 20, or a hole 5 for conveying the recording paper is provided.
It is also possible to use 01 as a reference mark.

It goes without saying that the present invention can also be applied to a color copying machine as shown in FIG.

As explained above, according to this embodiment, a reference mark is added to the recording paper when recording the first color, and the recording position for the next color is controlled according to this reference mark, so that the color laser beam It is possible to correct poor mechanical registration of each color in printers, etc., and enables high-quality, high-resolution, and highly accurate color recording. In addition, the reference mark is detected during the recording process for each color and corrected using electronic software, so it is easy to cope with changes in the quality of the recording paper due to changes in the equipment environment or changes in the recording paper at the user's request. This enables more stable and wide-ranging color image recording.

[0016]

As described above, according to the present invention, there are provided a plurality of photosensitive drums on which images of different colors are formed, a single other-face rotating mirror that deflects a plurality of laser beams, and An optical system that guides a plurality of laser beams deflected by a rotating mirror on the other side to the plurality of photosensitive drums to expose and scan each of the plurality of photosensitive drums, and a latent image obtained by the exposure scanning on the plurality of photosensitive drums. Since the structure includes an image forming means for forming images of different colors corresponding to the respective primary colors, and a multiplexing means for forming images of the respective different colors on the same transfer material by superimposing them on the same transfer material, Accurate recording positioning allows high-quality color image formation without color shift.

[Brief explanation of the drawing]

FIG. 1 is a layout diagram showing the configuration of a color copying machine.

FIG. 2 is a perspective view showing the configuration of a color copying machine used in the present invention.

FIG. 3 is an explanatory diagram showing the arrangement of reference marks.

FIG. 4 is an explanatory diagram showing an example of another reference mark used in the present invention.

[Explanation of symbols]

2,22 Laser oscillator 3 Laser modulator 4 Expander 5 Polygon mirror 20 Recording paper 101 Photosensitive drum for yellow 102 Photosensitive drum for magenta 103 Photosensitive drum for cyan

Claims (1)

[Claims] 1. A plurality of photosensitive drums on which images of different colors are formed, a single other-face rotating mirror that deflects a plurality of laser beams, and a plurality of laser beams deflected by the other-face rotating mirror. an optical system that guides a laser beam to the plurality of photosensitive drums to expose and scan each of the plurality of photosensitive drums, and forms images of different colors on the plurality of photosensitive drums corresponding to the latent images obtained by the exposure scanning. A color image forming apparatus comprising an image forming means and a multiplexing means for forming images of different colors on the same transfer material by superimposing them.