JPH0752468A - Multiple picture size-correcting device - Google Patents

Abstract

PURPOSE:To effectively correct a picture slipping of a multiple picture by arranging a picture size adjusting means which independently changes the line direction size of a recording image of a multiple picture means at each recording means. CONSTITUTION:A copier has three line sensors 101 on which filters of red, green and blue are applied, and one sheet of color draft is read by scanning the sensor 101, and electric image signals with three colors are generated. After performing a white correction and black correction of the image for respective color signals by a shading correction circuit 103, the brightness data (R, G, B) of the three colors is converted to density data (C, M, Y) by a LOG conversion circuit 104. Then, at a UCR (under color remove) circuit 105, minimum data of the density data is made black data, and C', M', Y' are made new density data. After correcting the signal 106 of C' by a picture slipping correction circuit 110, a laser 117 which is input in a laser driver 113 and performs a picture forming is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to laser scanning and LE.
The present invention relates to a multiple image size correction device for a multicolor printer that forms an image using a D array.

[0002]

2. Description of the Related Art In conventional multiplex printing, image magnification correction is performed only by mechanical manual adjustment, and subsequent processing such as automatic correction is not performed.

[0003]

Therefore, in the case of image formation by laser scanning, the formed image magnification changes due to temporal distortion due to heat of the mirrors related to the laser optical path and the parts supporting them. .

Further, in the image formation by the contact type LED array, since the LED array itself is manufactured by joining a plurality of small LED arrays, there is an inherent difference in size. Therefore, when a plurality of these are used to form a multiple image, a size difference occurs in each writing unit, and an image shift (color shift) occurs in the formed image.

The present invention is directed to image misregistration (color misregistration) of multiple images.
It is an object of the present invention to provide a multiplex image size correction device capable of effectively correcting the above.

[0006]

According to the present invention, in order to detect the amount of image shift (color shift) and automatically correct the image size of each image writing system, one image recording system is used as a reference. An image scaling unit is provided for each image writing system to perform correction so that each image size has a single value.

[0007]

1 is a block diagram showing the construction of a copying machine according to a first embodiment of the present invention. The details will be described below with reference to FIG.

First, the form of the copying machine will be described. The copying machine of this embodiment has three line sensors 101 coated with red, green and blue filters, respectively.
Scanning 1 scans one color original and scans 3
Generates a color electrical image signal. The image signal obtained at that time is A / D converted by the A / D converter 102 to be a digital image signal.

Further, the shading correction circuit 103 performs white correction and black correction of the image for each color signal. Next, the LOG conversion circuit 104 converts the luminance data (R, G, B) of the three colors into density data (C, M, Y). Next, UCR (under color re)
move) circuit 105, density data (C, M, Y)
The minimum data of the above is used as black data (Bk), and C ′ = C−Bk M ′ = M = Bk Y ′ = Y−Bk is used as new density data.

First, the C'signal 106 is corrected by the image shift correction circuit 110 and then input to the laser driver 113 to generate a laser 117 for forming an image.

The image signals of these four colors (C, M, Y, Bk) are formed by the device configuration shown in FIG.

In FIG. 2, the laser generated from the laser driver 113 is scanned by the polygon mirror 202 and a latent image is formed on the photosensitive drum 205 by the raster scan method. After that, cyan toner is placed on the latent image by the developing sleeve 206, and the paper fed from the arrow 210 is transported at a constant speed by the transport belt 211 to form a cyan image on the paper.

Similarly, a magenta image is formed by the laser 118, a yellow image is formed by the laser 119, and a black image is formed by the laser 120. The paper on which the four-color images are overlapped is fused and fixed by the fixing device 212, and the discharge unit 213
Is discharged to.

At this time, there is a distance D between each color drum,
The image must be delayed according to that distance. The magenta image signal is delayed by the delay circuit 110 to delay one drum (D) from the cyan image signal.
Similarly, the yellow image is delayed by the delay circuit 108 for two drums (2D), and the black image is delayed by the delay circuit 109 for three drums (3D) to align the images.

Next, when the cyan, magenta, and yellow images are multiplexed on the basis of the black image, the main scanning direction, the sub scanning direction, and the magnification correction 110 for eliminating the deviation are performed.
111 and 112.

Next, this correction method will be specifically described.
As shown in FIG.
As indicated by 308, cross patterns are printed with four colors at a predetermined interval (d). Black patterns 301 and 302 are paired on the left and right. Similarly, a pair of patterns is formed for yellow, magenta, and cyan.

This pattern is read by illuminating it with the lamp 214 of FIG. 2, and the line sensor 215 reads the infrared diffused reflected light of the cross pattern. The reading area is indicated by 309 and 310 shown in FIG. 3, and the cross pattern of each color is read at intervals d.

Further, the read cross patterns are shown in FIG.
As shown in, the addition operation of the data is performed in each of the main scanning direction and the sub scanning direction to obtain the center coordinates thereof. Then, a method of measuring and correcting the deviation from each of the obtained center coordinates will be described with reference to FIG.

First, 501 and 502 are black cross patterns serving as a reference, and 503 to 505 are color patterns for performing other corrections. Also, Ymarg
In indicates a sub-scan shift, which is adjusted by selecting how much the line memory 902 is delayed by the selector 903 in the correction circuit shown in FIG.

Further, a difference in image size due to a difference in size of each LED array can be obtained from the values of A and B in FIG. This shift is corrected by (A / B) times the line memory 904. According to the method, when (A / B) is smaller than 1 (reduction) by the write enable 905 and the read enable 906 of the line memory 903, the write enable 905 is thinned out as shown in FIG. A / B) reduction.
Similarly, when (A / B) is greater than 1, the value in FIG.
As shown in (b), by thinning out the read enable 906, it is enlarged by (A / B) times.

After that, in order to correct the deviation in the main scanning direction, with respect to the main scanning direction image reference position 505 shown in FIG.
It is necessary to shift the image by the pixel represented by D × A ÷ BC. The line memory 907 in FIG. 9 does this. In order to shift the image by the correction amount, correction is performed by the write enable 908 and the read enable 909. This correction shifts the image to the reference position side in (a) and to the opposite side in (b), as shown in FIG. By performing these image position correction controls, it is possible to create a multicolor image with no image shift or color shift.

Next, a second embodiment of the present invention will be described in detail with reference to FIG. First, the form of the copying machine will be described. The copying machine of this embodiment has three line sensors 601 coated with red, green, and blue filters, respectively, and scans the sensors 601 to read one color original document and generate electric image signals of three colors. . The image signal obtained at that time is A / D converted by the A / D converter 602 to be a digital image signal.

Further, the shading correction circuit 603 performs white correction and black correction of the image for each color signal. Next, the LOG conversion circuit 604 converts the three-color luminance data (R, G, B) into density data (C, M, Y). Next, a multi-separation circuit 605 for performing color separation separates a black image and a red image. After that, the red image signal is corrected by the image shift correction circuit 606, and then the LED array 6
The light 610 is input to the light source 08 and emits light 610 for forming an image.

Image signals of these two colors (red and black) are formed by a device configuration as shown in FIG. The image forming light from the LED array 608 is transferred to the lens array 70.
The image is formed on the photoconductor drum 703 by 2 to form a latent image. After that, red toner is applied to the latent image by the developing device 704, and the paper fed from the arrow 708 is conveyed at a constant speed by the conveyor belt 707 to form a red image on the paper. Similarly, the black image is the LED array 609.
Formed by. The paper on which the two-color images are superimposed is fused and fixed by the fixing device 709, and is ejected to the ejection portion 710.

At this time, there is a distance D between each color drum,
The image must be delayed according to that distance. The black image signal is delayed by the delay circuit 607 to delay one drum (D) from the red image signal.

Next, when the red image is multiplexed with the black image as a reference, the misalignment correction circuit 606 corrects the main scanning direction, the subscanning direction, and the magnification to eliminate the misalignment. This correction method will be specifically described. As shown in FIG. 8, cross patterns are printed on the sheet conveying belt 707 such as 801 to 804 with four colors at a predetermined interval (d).

The black pattern is composed of a pair of left and right like 801, 802, and similarly for the red pattern 803,
A pair of patterns is formed like 804. This pattern is read by illuminating it with the lamp 711 of FIG. 7, and the diffused infrared reflected light in the cross pattern is read by the line sensor 712.
Read with.

The reading area is 809 shown in FIG.
819, the cross pattern of each color is read at intervals d. Furthermore, for each cross pattern read, FIG.
As shown in, the addition operation of the data in each of the main scanning direction and the sub scanning direction is performed, and the center coordinates thereof are obtained.

Next, a method of measuring and correcting the deviation from each of the obtained center coordinates will be described with reference to FIG. 5
Reference numerals 01 and 502 are black cross patterns serving as a reference, and reference numerals 502 and 503 are color patterns for performing other corrections. Further, Ymargin indicates a sub-scan shift, which is adjusted by selecting how much the line memory 902 is delayed by the selector 903 in the correction circuit shown in FIG.

Further, depending on the values of A and B in FIG.
Deviation of color magnification is required. This shift is corrected by (A / B) times the line memory 904. The method is the write enable 905 of the line memory 903.
When (A / B) is smaller than 1 (reduction) by the read enable 906, the write enable 905 is reduced by (A / B) times by thinning out the write enable 905 as shown in FIG. Similarly, when (A / B) is larger than 1, as shown in FIG.
By thinning out, it is expanded to (A / B) times.

After that, it is necessary to shift the image by the pixel represented by D × A ÷ BC with respect to the image reference position 505 in the main scanning direction. The line memory 90 of FIG. 9 does this.
7 and to shift the image by the correction amount,
This is corrected by the write enable 908 and the read enable 909. This correction shifts the image to the reference position side in (a) and to the opposite side in (b) as shown in FIG.

By performing these image position correction controls,
It is possible to create a two-color image with no image shift or color shift.

[0033]

As described above, according to the present invention,
When creating a multi-color multiple image, it is possible to greatly simplify the device adjustment by automatically adjusting the individual image sizes with an electric circuit.
This is effective in multiple printing by a printer.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a device configuration of the first embodiment.

FIG. 3 is a plan view showing a cross pattern for position correction on the sheet conveying belt in the first embodiment.

FIG. 4 is an explanatory diagram showing a method of obtaining center coordinates of the cross pattern in the first embodiment.

FIG. 5 is an explanatory diagram illustrating a method of measuring and correcting a shift from the center coordinates of the cross pattern in the first embodiment.

FIG. 6 is a block diagram showing a second embodiment of the present invention.

FIG. 7 is a configuration diagram showing a device configuration of the second embodiment.

FIG. 8 is a plan view showing a cross pattern for position correction on the paper transport belt in the second embodiment.

FIG. 9 is a block diagram showing a configuration of a correction circuit used in each of the embodiments.

FIG. 10 is a waveform diagram illustrating the principle of reduction and enlargement for correcting the image size in each of the above embodiments.

FIG. 11 is a waveform diagram illustrating the principle of shift for correcting the position in the image main scanning direction in each of the above-described embodiments.

[Explanation of symbols]

 101 ... Line sensor, 102 ... A / D converter, 103 ... Shading correction circuit, 104 ... LOG conversion circuit, 105 ... UCR circuit, 107-109 ... Delay circuit, 110-112 ... Image shift correction circuit, 113-116 ... Laser driver.

Claims (3)

[Claims] 1. A plurality of recording means for recording images line-sequentially, and a multiplexing means for superimposing the recorded images by the plurality of recording means to form a multiplexed image, A multiple image size correction apparatus, characterized in that each of the recording means has an image size adjusting means that can be changed independently. 2. The image size adjusting means according to claim 1, wherein one of the recording means is used as a reference image size, the image size adjustment is not performed for the recording means, and the image size is adjusted by another recording means. A multiple image size correction device characterized by matching the reference image size by doing so. 3. The multiplex image size correction device according to claim 2, wherein the multiplex image includes a black image and a color image other than the black image, and the reference image size is based on the black image.