JPH07221952A - Image processor - Google Patents

Abstract

PURPOSE:To process an image even when the image is formed by using plural lasers without causing deviation of images by detecting an optical path of a laser beam and correcting image data depending on the optical path. CONSTITUTION:An output signal from an image processing section 102 is given to a laser driver 201. The driver 201 controls a stimulated beam from lasers 202, 203 to emit the laser beam. Data for a black/white image are emitted from the laser unit 203 and the image is formed on a photoreceptor drum 214 via a decahedron mirror 205, an image forming lens 207 and a mirror 8. Furthermore, data for a red image are formed on the drum 214 from the laser unit 202 via a decahedron mirror 204, an image forming lens 206, and a mirror 209. In this case, the laser beam is given also to light receiving sections 210-213 and its output signal is given to the image processing section 102. The processing section 102 calculates the emission time from an input signal and calculates the optical path based thereon and corrects the image data depending on the optical path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus such as a digital copying machine or a facsimile.

[0002]

2. Description of the Related Art Conventionally, in an image processing apparatus, for example, an electrophotographic digital copying machine, an original is irradiated with a halogen lamp or the like, and the reflected light is photoelectrically converted by using a charge coupled device such as a CCD, and then digitally converted. After converting to a signal and performing a predetermined process, an image is formed using a laser.

Further, by using a plurality of lasers,
It has realized colorization and speedup of recording devices.

[0004]

However, when forming an image using a plurality of lasers, the parallelism of the respective lasers is important, and the recording accuracy of the image may be deteriorated due to a slight difference in the irradiation direction of the laser light. There was a problem of deterioration.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an image processing apparatus capable of correcting the inclination between the respective beams when a plurality of lasers are used.

[0006]

According to the present invention, in an image processing apparatus for forming image information by a plurality of lasers, a detecting means for detecting an optical path of laser light from the lasers and a detecting result by the detecting means are provided. And a correction means for correcting the image signal.

[0007]

According to the present invention, the optical path of the laser beam from the laser is detected by the detecting means, and the image signal is corrected by the correcting means according to the detection result.

[0008]

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

<First Embodiment> (Outline of Processing) FIG. 1 is a block diagram showing the arrangement of a copying machine.

The full-color original 100 is exposed by an exposure lamp (not shown), the reflected color image is picked up by the CCD image sensor 101b, the picked-up image signal is processed, processed, and output to the printer 103. ing.

The color information of the original 100 is obtained by the image reading unit 1.
CCD image sensor 1 through lens 101a of 01
The image is formed at 01b. CCD image sensor 101b
Reads each line at 400 dpi for R (red), G (green), and B (blue). The read signal is output as an analog signal and input to the A / D converter 101c that converts the analog signal into a digital signal. The digital signal from the A / D converter 101c is input to the image processing unit 102.

In the image processing unit 102, shading correction is performed by a shading correction circuit 102a, and R,
Image data of 8 bits for each of G and B is generated. In the data processing unit 102b, various image processing is performed from the R, G, and B image data read by the CCD image sensor 101b, and image data of 8-bit black and red luminance is created. This is because the image of the color original is printed in red and black.

Next, the output signal of the data processing unit 102b is input to the image correction units 102c and 102d, and the data in the recording direction of the laser is calculated by interpolation calculation.

Further, the output of the image correction units 102c and 102d is converted into the density data by the brightness density conversion unit 102e, and the print data for the printer 103 is generated. The printer 103 includes a control circuit such as a motor that conveys a sheet, a laser recording unit that writes input image data on a photosensitive drum, and a development control circuit that performs development. In addition, the CPU circuit unit 104 includes the CPU 1
04a, ROM 104b, RAM 104c,
The image reading unit 101, the image processing unit 102, the printer 103, and the like are controlled to collectively control the sequence control of the copying machine.

(Exposure Control Section) FIG. 2 is a block diagram of the exposure control section. The output signal of the image processing unit 102 shown in FIG. 1 is input to the laser driver 201. The laser driver 201 controls the emission of laser light, and emits laser light from a laser unit including a laser, a collimator lens, and a cylindrical lens.

The laser light is incident on the decahedral mirror which is rotating at a constant speed. The laser light reflected from the decahedral mirror is focused on the photosensitive drum by the imaging lens arranged in front of the decahedral mirror. At this time, the optical path of the light emitted from the imaging lens is bent by the laser mirror.

The data for the black and white image is the laser unit 20.
An image is formed on the photosensitive drum 214 by the decahedron mirror 205, the imaging lens 207, and the mirror 208.

The data for the red image includes the laser unit 202, the decahedron mirror 204, and the imaging lens 206.
Then, an image is formed on the photosensitive drum 214 by the mirror 209.

At this time, the laser light is input to the light receiving portions 210 to 213 in addition to the photoconductor 214. The light receiving unit is composed of a slit and a light receiving element, and the slit has two right-angled isosceles triangle parts missing as shown in FIG.
In FIG. 3, 210 to 214 indicate the same parts as in FIG.

The light receiving element outputs an analog electric signal to the image processing section 102 when the laser beam is irradiated. The image processing unit 102 calculates the irradiation time from the analog signal.

The irradiation time of the light receiving element varies depending on the laser scanning position as shown in FIG. When the laser scanning direction is ideal, as shown in FIG. 4 (a), the time t1, t2, and time when the light receiving element is irradiated through the slit.
This is the case where t3 and t4 are all equal. On the other hand, when the scanning direction is not ideal, the times t1, t2, t3, and t4 do not have the same value as shown in FIG. 4B.

Therefore, a method of detecting the laser scanning direction will be described with reference to FIG.

The ideal laser scanning direction is the x-axis, and the side of the slit 1 that intersects the x-axis at a right angle is the y-axis. A parallel line passing through the midpoint between the hypotenuse of slit 1 and the hypotenuse of slit 2 is y
= X-a. If a> 0, the intersection with the x-axis is A
(A, 0). A line passing through the midpoints of the hypotenuses of the slit 3 and the slit 4 is represented by y = x-b (b> 0). x
The intersection with the axis is B (b, 0).

Here, assuming that the laser irradiation direction is the direction shown in FIG. 5, the slit 1 causes the light receiving element to t.
The waveform for 1 hour is output, and the output waveforms for time t2, t3, t4 are similarly obtained from the slits 2, 3, 4.

The intersections of the laser and the line of y = x-A, y = x-B are C and D. Here, the distance traveled by the waveform at the times t1, t2, t3, t4 obtained from the light receiving element can be easily calculated from the rotation speed of the polygon mirror.
Here, the distances that have passed during the times of t1, t2, t3, and t4 are defined as T1, T2, T3, and T4. Then, the coordinates of points C and D are

[0026]

## EQU1 ## C ((T1-T2) / 2 + a, (T1-T2) / 2) D ((T3-T4) / 2 + b, (T3-T4) / 2).

From this, the formula of the straight line passing through the points C and D is

[0028]

## EQU00002 ## If h = ba, .DELTA.T1 = T1-T2, .DELTA.T2 = T3-T4,

[0029]

[Equation 3]

It becomes h indicates a distance between slits arranged on both sides of the photosensitive drum.

Next, the concept of image data correction will be described with reference to FIG.

It is assumed that the data generated by the data processing unit 102b are j-1 line, j line, and j + 1 line in order, and the laser irradiation direction is the direction of the straight line shown in FIG. Now, when the pixel of interest is the coordinate E (i pixel on the j-th line), if it is along the j-th line in the laser irradiation direction, it may be output as it is, but the laser irradiation direction is the direction of the straight line in FIG. When, the data of the coordinate F must be output. If the data of coordinate F is subjected to linear interpolation from the data of coordinates E and G,

[0033]

## EQU4 ## (d1E + d2G) / (d1 + d2). Here, in d1 and d2, x is i
It is calculated from the value of y at the time.

FIG. 8 shows the image correction section 102c, 1 shown in FIG.
It is a block diagram which shows the structure of 02d. In FIG.
Data is set in the register 302 by the CPU 104a, and the inclination of the laser is set in the register 300. In the adder 301, the slope is added for each synchronization signal. The offset level set in the register 302 is added by the adder 303.

In the register 308, the CPU 104a calculates which line of the image data is between the 0th pixel in the main scanning direction, and the FIFOs 313 to 31.
Selector 31 for selecting which line between 6
A value for selecting 7, 318 is loaded, and whether the counter is an up counter or a down counter is controlled by the inclination. The offset value at the 0th pixel is set in the register 302, the slope is set to 300, and is set by the CPU. In the adder 301, it is added as the pixel progresses,
The adder 303 adds the offset value. Adder 30
When the bit carry is 1 or 303, it indicates that the line to be referred to when the image data is interpolated has moved.

The carry signal is input to the up / down counter via the OR gate 321 to count up / down. In addition, the counters are selectors 317 and 3
Although it is input to 18, the line of the output image data is changed by one line.

The output of the adder 303 is the subtractors 305 and 30.
7. Input to selectors 311 and 312. If the inclination is +, for example, as shown in FIG. 6, the register 3
"0" is set to 11,312 by the CPU 104a, and the A input of the selectors 311 and 312 is selected and output. The distances (d1 + d2) between the lines are set in the registers 304 and 306, and the subtractor 305 outputs d2. When the inclination is −, for example, FIG.
In the case as shown in FIG.
Is set, and the selectors 311 and 312 output the B input. Selector 3 in multipliers 319 and 320
The output of 17, 318 and the calculation are performed, and the registers 322, 3
The output of the multiplier is multiplied by the distance between the lines set to 23 and output.

Further, the image correction units 102c and 102d have the same configuration, and C is set in accordance with the inclination of each laser beam.
The value set in the register differs depending on the PU 104a.

In this way, the respective optical paths of the black laser light and the red laser light are detected, and the respective image data are controlled according to the optical path of the laser light, so that the scanning of the laser light is performed. Even if the directions are not parallel, it is possible to perform processing without causing a deviation between an image output in black and an image output in red.

<Second Embodiment> FIG. 9 shows a second embodiment of the present invention.

In the first embodiment, the data for the black image and the data for the red image are obtained by interpolating from the data of the lines before and after, respectively, but in the present embodiment, only the data for the red image is obtained. Image correction was performed. That is, FIG.
Is different from the output data of the data processing unit 102b. The data for the black image is directly input to the brightness / density conversion unit 102e without performing the interpolation calculation, and the data for the red image is input to the image correction unit 102c. Interpolation calculation is performed and the result is input to the brightness density conversion unit 102e.

A method of interpolating red image data will be described with reference to FIG.

Now, laser light for black image (laser light 1)
Is the direction of the solid line in FIG. 10A, and the laser light for red image (laser light 2) is the solid line in FIG. 10B. Further, it is assumed that the laser light 1 passes through the point A and the inclination is a, and the laser light 2 passes through the point B and the inclination is b.

Then, the black image laser light is generated on the i line at the point A at which the data of the kth pixel is separated by the distance d1. At this time, the laser beam for the red image also passes through the point distant from the j line by d1, and if the inclination b is b = a, the position of the image is not displaced.

However, if the directions of both laser beams are deviated, an image deviates between black and red. Point B of laser beam 2 is j
It is assumed that the k pixel on the line deviates from the original position by d2. At this time, since the laser beam 1 is deviated by d1, the data at the point B must emit the data at the point C deviated from the pixel D by d2-d1. Considering in the same way, the image formed by the laser beam 2 must be the data of the data line 1. That is, it is data on a straight line that passes through the point C of k pixels and has a slope of ba.

Since the subsequent setting is the same as that described in the first embodiment, the description will be omitted.

[0047]

As described above, according to the present invention,
Since the optical path of the laser light is detected and the image data is corrected according to the optical path, even if an image is formed by a plurality of lasers, the processing can be performed without causing the image shift.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of a copying machine.

FIG. 2 is a block diagram showing a configuration of a laser processing unit.

FIG. 3 is a diagram showing a positional relationship between a photosensitive drum, a slit, and a detector.

FIG. 4 is a diagram showing a laser scanning direction and a waveform detected by a detector.

FIG. 5 is a diagram showing a coordinate system for detecting a laser scanning direction.

FIG. 6 is a conceptual diagram for detecting a laser scanning direction.

FIG. 7 is a conceptual diagram for detecting a laser scanning direction.

FIG. 8 is a detailed block diagram of an image correction unit.

FIG. 9 is a block diagram showing an overall configuration of a copying machine according to a second embodiment.

FIG. 10 is a conceptual diagram showing a method of correcting image data.

[Explanation of symbols]

 100 original document 101 image reading unit 101a lens 101b CCD 101c A / D converter 102 image processing unit 102a shading correction circuit 102b data processing unit 102c, 102d image correction unit 102e luminance density conversion unit 103 printer 104a CPU 104b ROM 104c RAM

Claims (1)

[Claims] 1. An image processing apparatus for forming image information by a plurality of lasers, a detecting means for detecting an optical path of a laser beam from the lasers, and a correcting means for correcting an image signal according to a detection result by the detecting means. An image processing apparatus comprising: