JPS6159373A - Forming device for polychromatic image - Google Patents

Abstract

PURPOSE:To eliminate the need for an expensive memory and a delay circuit by splitting luminous flux to be image-formed at an eraser irradiation position from an optical path of exposure, and arranging a color image sensor so that the image formation position of this luminous flux is an incident position. CONSTITUTION:An eraser 4 is so arranged that its irradiation is in an image slit on a photosensitive drum 1 and a position 20 off the center 18 of the slit 18; and a light beam which forms an image at this position is emitted from a position 22 off the center 21 of an irradiation slit on an original in a scanning direction and the optical axis of the lumnous flux reaches a photosensitive body 1 through a path shown by a broken line. The eraser 4 cuts off the corre sponding part of the luminous flux and the color image sensor 9 is so arranged that the image formation position of part of transmitted luminous flux split by a half-mirror 7 which has its optical axis as shown by the broken line in a figure is the incidence position. The image at the position 22 on the original is read by a sensor 9, whose output is processed; when the eraser 4 is operated immediately, erasure is performed to process the image at the position 22 on the original.

Description

[Detailed description of the invention] Technical field The present invention relates to a multicolor image forming apparatus.

Conventional multicolor image forming apparatuses have conventionally exposed and scanned a document three times, each time inserting color filters of blue, green, and red, which are the six primary colors of light, in multiple exposure paths, and capturing the reflected light beam of the document. The electrostatic latent images obtained by color separation and exposure of the photoreceptor are developed with yellow, magenta, and cyan toners, which are the three primary colors of the subtractive color method, to form three-color toner images. It is known that the images are superimposed and transferred onto a single sheet of transfer paper to obtain a full-color copy.

Theoretically, it should be possible to reproduce all colors, including black, by appropriately mixing the three colors yellow, magenta, and cyan, but in reality, the spectral transmittance characteristics of color separation filters and the color toner's Because the spectral reflectance characteristics differ from ideal characteristics, it is not always possible to reproduce the color tone, gradation, and sharpness of the original. There are also cases where it is desired to change the color tone of the document itself. In addition, office documents often have black characters, and in order to make black and white copies, they must be passed through a color separation filter.
The system in which six-color toner images are superimposed and transferred through multiple exposures not only does not produce a desirable black color, but also has the disadvantage that color shift is noticeable in thin characters, resulting in a large loss of light meter and time.

As a multicolor image forming apparatus that solves these intercondylar points, as illustrated in FIG. The yellow, magenta, and cyan colors are developed tTi on the downstream side in the rotational direction of the exposure position 18 of the drum 1.
10.11.12 followed by developer 1 with black toner
At the same time, a half mirror 7 is provided between the exposure optical system lens 6 and the filter 8 to divide the slit exposure beam and extend in the width direction of the photoreceptor drum 1 at the imaging position of the half mirror transmitted beam. A color image sensor 9 is provided, and a light emitting element (LED) extends in the axial direction of the photoreceptor drum 1 between the exposure position 18 of the photoreceptor drum and the yellow developer 10.
A multicolor copying apparatus has been proposed which is provided with an eraser 4 consisting of an array.

The above color image sensor 9 has a filter array in which blue, green, and red filters are arranged repeatedly in front of the light receiving elements of the CCD array, and one set of blue, green, and red filters is arranged in correspondence with each light receiving element. Five components of the color of light emitted from the pixel corresponding to the red filter are detected by the outputs of six light receiving elements. One light-emitting element of the eraser 4 is provided corresponding to each filter of the color image sensor 901 set, and the color detected from the output of one set of light-receiving elements of the color image sensor is processed by an arithmetic processing circuit to produce a blue color. Image processing is performed by controlling each light emitting element of the eraser 4 to blink during four exposures through four color filters 8, green, red, and colorless, respectively.
By developing with cyan and black developing devices and superimposing and transferring the obtained four-color toner images onto transfer paper wound on the transfer drum 14, an image with desired color tone, gradation, and sharpness is created. is obtained. For example, in the process of developing yellow, magenta, and cyan, an image portion determined to be black by the color image sensor 9 is neutralized by an eraser and is not developed with color toner, and in the process of developing with black toner, other parts are erased. The charge is removed by the process, and only the black image area is developed with black toner, resulting in a pure black image with no sharp color shift. In addition, various color corrections can be performed according to preset processing programs.

In FIG. 6, 2 is a static eliminator, 6 is a charger, 15 is a pre-transfer static eliminator, 16 is a pre-cleaning static eliminator, and 17 is a cleaning unit.

Now, in the conventionally proposed apparatus having the configuration illustrated in FIG. The output from the color image sensor 9 is instantaneously processed, so it is input directly to the eraser 4, causing the eraser's light emitting element to blink, and at position 19 in Figure 3. When the photoconductor is erased, it is exposed to light rays emitted from the same position on the document =
4- This will erase a position that is a length between 18 and 19 ahead of the specified position. Therefore, a memory is installed between the output side of the processing circuit for the output from the color image sensor 9 and the eraser 4.
It is necessary to input the data to the eraser 4 with a delay of the time required for the data to rotate between the exposure position 18 and the erase position 19. Since memory is expensive, it has the disadvantage of increasing the cost of the device.

Purpose The present invention eliminates the above-mentioned drawbacks of conventionally proposed multicolor copying devices that process images by reading a document using the color image sensor, processing the output, and inputting the output to an eraser, thereby eliminating the need for expensive memory. An object of the present invention is to provide a multicolor image forming apparatus.

Structure In order to achieve the above-mentioned object, the present invention arranges the eraser so that its irradiation position is off the center of the slit within the image exposure slit on the photoreceptor, and forms an image at the above-mentioned eraser irradiation position. The present invention is characterized in that the color image sensor is arranged so that the light beam is separated from the path of the dew tip and the image formation position of the light beam is the incident position.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment in which the present invention is applied to the conventionally proposed device shown in FIG. Therefore, the same members will be described with the same reference numerals.

In this embodiment, the eraser 4 is arranged so that its irradiation position is at a position 20 within the image exposure slit on the photosensitive drum 1, which is off from the slit center 1B. The light beam that forms an image at this position is emitted from a position 22 that is shifted in the scanning direction from the center 21 of the illumination slit on the original, and the optical axis of the light beam follows the path shown by the broken line in the figure and reaches the photoreceptor. Reach 1.

However, a considerable portion of the light beam is blocked by the eraser 4. The color image sensor 9 is arranged so that the imaging position of the transmitted light beam divided by the half mirror 7, the optical axis of which is the above-mentioned broken line, is the incident position.

This exposure optical system is a 1-magnification imaging optical system, so the photoreceptor
- Image exposure slit center 18 and eraser irradiation position 20
and the distance between the irradiation center 21 on the document and the starting point 22 of the light beam reaching the eraser irradiation position 20 are equal. Therefore, if the image at position 22 on the original is read by the color image sensor 9, the output is processed, and the eraser 4 is activated immediately, the image at position 22 on the original will be erased. become. At this point, the exposure slit center 18 is exposed to the image at the irradiation center 21 of the document, but the image at the irradiation center 21 of the original is exposed to light, and the time required for points 1 to 8 on the photoreceptor drum to rotate to position 20 on the photoreceptor is Since 22 images on the document were previously exposed at the center of the exposure slit, image processing is performed appropriately.

Therefore, there is no need to provide a memory and a delay circuit between the output processing circuit of the color image sensor 9 and the eraser 4.

The means for separating the light flux reaching the irradiation position 20 of the eraser 4 from the exposure paths is not limited to the half mirror 7 of the embodiment 1, but as shown in the embodiment of FIG. -7 may be a mirror 7a, a mirror 7b may be inserted in a part of the optical path between the mirror 7a and the filter 8, and the color image sensor 9 may be provided at the imaging position of the reflected light indicated by the broken line. Other configurations are the same as the embodiment shown in FIG. Since the operation of this device is obvious from the explanation of the operation of the embodiment shown in FIG. 1, the explanation will be omitted.

Effects As described above, according to the present invention, the expensive memo 'J- and delay circuit are not required, so that the cost of the apparatus can be reduced.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are sectional views showing embodiments of the present invention, respectively;
FIG. 3 is a sectional view showing the structure of an example of a conventionally proposed multicolor copying apparatus. 1... Photosensitive drum 4... Eraser 5...
Exposure lamp 7b... Mirror in optical path 8... Color separation filter 9... Color image sensor 10
~13...Developer 1B...Image exposure slit center 20...Eraser irradiation position Fig. 1 Fig. 2

Claims (1)

[Claims] The original placed on the contact glass is irradiated with an exposure lamp, an image is formed on the photoreceptor through the exposure optical system, and slit exposure is performed. The image forming area of the photoreceptor is selected for each erase unit by reading and processing the output and selectively blinking each element of the eraser, which is made up of a light emitting element array that extends in the width direction along the photoreceptor. In a multicolor image forming apparatus that performs image processing by erasing images, the eraser is arranged so that its irradiation position is off the center of the image exposure slit on the photoconductor, and the eraser is A multicolor image forming apparatus characterized in that the above-mentioned image sensor is arranged such that a light beam to be imaged at an irradiation position is separated from the exposure paths and the image formation position of this light beam is an incident position.