JPH04148948A - Electrophotographic printer - Google Patents

Abstract

PURPOSE:To eliminate the positional shift of an exposure means by automatically adjusting the position of said means by calculating the positional shift of the exposure means on the basis of a measured measuring pattern position to adjust the positional shift of the exposure means. CONSTITUTION:In the position adjusting mode of an exposure means 3 such as an LED array, a measuring pattern generating part 21 generates a predetermined measuring pattern image, for example, a reticule pattern image to record a reticule pattern CRP on recording paper. After the reticule pattern is recorded, a position measuring part 22 measures the position of the pattern CRP recorded on the recording paper 12 and a positional shift operation part 23 calculates the inclination of the exposure means 3 with respect to a drum rotary shaft direction (longitudinal direction) or the positional shift of recording in main scanning and sub-scanning directions on the basis of the measured pattern position and an exposure means position adjusting part 24 adjusts the inclination or position of the exposure means 3 on the basis of the calculated inclination or positional shift to perform recording at an accurate position.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Conventional technology (Figures 15 to 17) Problems to be solved by the invention Means for solving the problems (Figure 1) Effect (Figure 1) Figure 1) Embodiment (a) An embodiment of the present invention (Figures 2 to 11) Arrangement of the position measuring section (Figure 2) Configuration and operation of the position measuring unit (Figures 3 to 6) Cross Relationship between line pattern storage position, inclination, and positional deviation (Fig. 7) Positional deviation measurement processing of microcomputer and position = 3-control processing (Figs. 8 and 9) - First embodiment of exposure means position adjustment section (Fig. 10) - Second embodiment of the exposure means position adjustment section (Fig. 11) (b) Positional deviation adjustment operation - Overall operation (Fig. 12) - Positional deviation measurement processing (Fig. 13) - Position Adjustment processing (Fig. 14) (c) Other embodiments of the invention Effects of the invention [Summary] Positional deviation of the exposure means that exposes the photosensitive drum to form an electrostatic latent image based on image data to be recorded is corrected. Regarding electrophotographic printers that automatically adjust, the position of the exposure means can be adjusted automatically even if the exposure means such as an LED array is not mounted on the printer body with high accuracy or even if the position of the recording is misaligned. !
! The purpose of the present invention is to provide an electrophotographic printer that can record images without any positional deviation, and in the case of a color printer, can eliminate color deviation. an open-side pattern generation unit that records the measurement pattern on the storage medium, a position measurement unit that measures the position of the measurement pattern recorded on the recording medium, and a position deviation that calculates the position deviation of the exposure means based on the measured measurement pattern position. It is configured to include a calculation section and an exposure means position adjustment section that adjusts the positional deviation of the exposure means.

[Industrial Application Field] The present invention relates to an electrophotographic printer, and more particularly to an electrophotographic printer that automatically adjusts the positional deviation of an exposure means that exposes a photosensitive drum to form an electrostatic latent image based on image data to be recorded. Regarding.

Electrophotographic printers include laser printers and LED
Printers, liquid crystal printers, and various other products have been developed. These electrophotographic printers each use a laser optical system, an LED array optical system, and a liquid crystal shutter array optical system in the exposure section, and are characterized by high speed, high resolution, and high image quality, and are expected to develop significantly in the future. It is expected that.

Further, as printers become more sophisticated, the need for color printers will increase, and it is expected that electrophotographic color printers with features of high image quality and high speed will be increasingly used.

[Prior Art] FIG. 15 is a block diagram of a conventional high-speed LED color printer, which uses an LED array in the exposure section. This color printer has four sets of recording units RUI to RU4 for recording four colors including the three primary colors yellow, magenta, and cyan, plus black. Each recording unit includes a photosensitive drum (photoconductor drum) 1, a charger 2, an exposure means 3 such as an LED array, a developer 4, a cleaner 5, and a transfer device 6. Each recording unit l-R, U
1 to RU4, well-known electrophotographic recording is performed, and color image quality 1 is recorded on the photosensitive drums 1 and 2 by a color 1-ner.
It is formed. The recording sheets of the paper rollers 1 to 7 are picked up by a pickup roller 8 and conveyed under each recording unit by a recording sheet conveyance system 9. When the recording paper reaches the position of each photosensitive drum 1-, the color 1 to color images formed on the photosensitive drum 2 are transferred onto the recording paper by a transfer device 6. The recording paper on which the four colors have been transferred is fixed on the recording paper by melting l/ner by heat in the fixing device 10, and is output to the stacker 11. A color printer with this configuration is capable of high-speed printing because each printing unit performs printing operations in parallel in a pipeline manner.

FIG. 16 is an outline drawing of the LED array, in which a large number of LED array chips 3b and a driver IC chip 3 for causing the LED elements to emit light are mounted on a ceramic printed board 3a.
A SELFOC lens (Nippon Sheet Glass type) 3d for guiding light generated from each 17EI element to the photosensitive drum is held at a constant interval d. A plurality of LED elements are mounted on each L E I) array chip 3b, and the number of LED elements required to record -'/- one line in the main scanning direction (direction perpendicular to the paper feeding direction) is The elements are arranged in a straight line. The driver IC chip 3c has T and the same number of films as the ED array chip 3b on both sides of the LED array chip 3b.
A drive circuit is provided for driving the element. Since the ceramic printed circuit board 3a has high thermal conductivity, L
The heat generated by the ED array chip is efficiently transferred to the entire board to cool the chip.

FIG. 17 is a configuration diagram of the driver IC chip, in which a shift register 3cm1, a latch circuit 3C-2, an LED driver 3cb-3, etc. are provided. One line of image data (image data) IMD is transferred and serially shifted in the shift register 3C-1 in synchronization with the lock CL.

As a result, when one line of image data IMD is aligned in the shift register 3cm1 of all driver IC chips, it is latched by the latch circuit 3cm2 by the latch signal Ts, and then the light emission enable signal Es is generated.
The LED element corresponding to the image data of `` is driven to emit light, and the photosensitive drum is exposed to light through the SELFOC lens 3d (Fig. 15), and a one-line electrostatic latent image is formed on it. By inputting image data serially, the number of signal lines can be reduced.

This simplifies the control of the LED array.

[Problems to be Solved by the Invention] In such a conventional color printer, the recording units 1 to 4 are
Since the arrays are arranged side by side, if the positions of the exposure dots in each array are different, there is a problem in that color shift occurs and the output image deteriorates. For this reason, four sets of T,
It is necessary to maintain the position of the ED array with high precision. However, there is a problem in that the recording position may shift due to changes in the environment in which the printer is used, changes over time, or the like.

In addition, when maintaining the printer device and replacing the exposure unit or photosensitive drum, it is necessary to adjust the recording position, but this position adjustment takes a long time and the printer cannot be used during this time. As a result, service deterioration has become a problem.

Furthermore, in order to mount the four sets of LED arrays on the printer body with high precision, the precision of the entire printer must be improved, and there is a problem in that high component precision is required.

In addition, alignment adjustment is complicated and requires skill, and the number of adjustment steps increases, which is reflected in the cost of the printer and increases the cost.

From the above, the first object of the present invention is to automatically determine the position of the exposure means, even if the exposure means such as an LED array is not mounted on the printer body with high accuracy, or even if the recording position is changed. To provide an electrophotographic printer capable of recording without positional deviation through adjustment and eliminating color deviation in the case of a color printer.

A second object of the present invention is to provide an electrophotographic printer in which the inclination of the exposure means and the deviation of the recording position in the main scanning direction and the sub-scanning direction can all be adjusted.

A third object of the present invention is to provide an electrophotographic printer in which positional deviation and tilt can be easily measured.

A fourth object of the present invention is to provide an electrophotographic printer in which the inclination of the exposure means can be adjusted with a simple configuration.

A fifth object of the present invention is to provide an electrophotographic printer that can automatically adjust the recording position at an appropriate time.

A sixth object of the present invention is to provide an electrophotographic printer that can issue a warning if the recording position is incorrect even after performing position adjustment a predetermined number of times.

[Means to solve the problem] FIG. 1 is a diagram explaining the principle of the present invention.

1 is a cylindrical photosensitive drum, 3 is an exposure means such as an LED array arranged in the longitudinal direction of the photosensitive drum, and 21 is a predetermined measurement pattern (
A measurement pattern generator 22 generates a crosshair pattern) and records the pattern on the recording paper 12, and 22 is a position measurement unit that measures the position of the measurement bats (crosshair patterns) CR and P recorded on the recording paper 12. 23 is a positional deviation calculation unit that calculates the positional deviation of the fogging means based on the measured pattern position; 24 is an exposure means position adjustment unit that adjusts the positional deviation of the exposure means; 24. a is a motor driver, 24b
24-c is a motor, 24-c is an exposure means support, and 24C is a ball screw threadedly engaged with the support.

[Function] When the exposure means 3 such as the LED array enters the position adjustment mode, the measurement pattern generating section 2 generates a predetermined measurement pattern, for example, a crosshair pattern image, and the crosshair pattern C
Record the RP on recording paper 2.

After recording the crosshair pattern, the position measurement unit 22 measures the position of the pattern CRI recorded on the recording paper 12, and the position deviation calculation unit 23 determines the direction of the drum rotation axis of the exposure means 3 based on the measured pattern position. The exposure means position adjustment unit 24 adjusts the inclination and position of the exposure means 3 based on the calculated inclination and positional deviation. , record it in the correct position.

As shown in the following, the position of the exposure means is adjusted so that the inclination and positional deviation of the exposure means are zero, so recording can be made without positional deviation, and in the case of a color printer, color deviation can be eliminated. . In addition, since the inclination and positional shift of the exposure means can be automatically adjusted, the adjustment can be made in a short time, preventing service degradation and failure, and does not require any skill.

Incidentally, if the exposure means position adjustment section is configured by a motor 24b attached to the printer body, a ball screw 24d or a cam that is rotated by the motor, and an exposure means support 24c that is rotated by the rotation of the ball screw or cam, The inclination of the exposure means can be adjusted with a simple configuration.

In addition, even if the position adjustment and recording operation after position adjustment are performed a predetermined number of times, an error message will be displayed if the positional deviation claw does not fall below the allowable value, thereby preventing erroneous recording with poor recording conditions. We are able to respond promptly and
Furthermore, by performing the position adjustment mode every time a predetermined number of sheets are recorded, it is possible to always record without positional shift or color shift.

[Example] (a) Example 1I of the present invention! l;tjgPa1- FIG. 2 is an explanatory diagram of the arrangement of the position measuring section when the present invention is applied to an electrophotographic color printer, and 22 is the position measuring section.

In FIG. 2, the difference from the conventional example (see FIG. 15) is that a position measuring section 22 is provided after the fixing device "-0", and the position measuring section 22 uses the measurement pattern recorded on the recording paper, e.g. The position of the crosshair pattern consisting of lines and horizontal lines is detected, and based on the detection result, an exposure means 3 such as an LED array is used.
The point is that the position of is adjusted. Note that ]-4 is a paper guide.

As shown in FIG.
Types of light emitting diodes (light sources) 22r, 22g, 22b
, a lens 22Q, and a CCD line sensor 22s, and as shown in FIG. 4, two sets of the recording paper 12 are set slightly inward from both left and right ends of the recording paper 12.

When the exposure means 3 enters the position adjustment mode, each recording unit 1
to RUB,,RU2. RU3. R1J4. (Fig. 2) is a measurement pattern consisting of vertical lines and horizontal lines in sequence on both sides of the recording paper 12. Tombow marks (cross line patterns) CRPc, CRPm, CRPy, (, RPb) are recorded. After the pattern is recorded, record paper 1
2 is sent, and the red light emitting diode 22r emits light at the timing when the cyan crosshair pattern CRPc comes under the position measuring unit 22, and the magenta crosshair pattern CRPm is sent.
The green light emitting diode 22 emits light at the timing when
? At the timing when y comes under the position measuring unit 22, the blue light emitting diode 22b emits light, and the black crosshair pattern C
RI) The red (or green or blue) light emitting diode 22r emits light at the timing when b comes under the position measuring unit 22, and while each light emitting diode emits light, the recording paper 12
Cyan, magenta, yellow, and black recorded images (crosshair patterns) on both sides are read by the CCD line sensor 22s. i.e. cyan toner image (crosshair pattern)
is lit while the red LED is lit, the magenta toner image is lit while the green LED is lit, and the yellow toner image is lit while the blue LED is lit.
The black toner image is read during the second flash of the red light emitting diode. Note that each light emitting diode emits light until the recording paper is fed in the sub-scanning direction and a crosshair pattern of N dot lines is read.

The pattern image signal read by the CCD line sensor 22s of the position measurement unit 22 is sequentially read out pixel by pixel by the CCD control circuit (continuation circuit) 31- in FIG. amplified (
(see signal S1 in FIG. 6) is converted into a binary digital signal by an AD converter or comparator 32 (see signal S2).

After that, the binary digital image is divided into cyan, magenta,
Microcomputer 3 as a positional deviation calculation unit for each yellow and black color
3 are sequentially stored in the built-in memories 33c, 33m, 33y, and 33b (see patterns M and P), and are used to calculate the tilt and positional deviation in the main scanning and sub-scanning directions in the position adjustment process of the exposure means, which will be described later. .

The relationship between the cross line pattern position and positional deviation in Figure 7 is read from the recording paper and stored in the memory 33C233m, 33y.
, 33b, cyan, magenta, yellow, and black crosshair patterns CRP c, CRPm + C
This is an example of RPy' and CRPb', with 2 left and right for each color.
Seven character line patterns are stored, but in FIG. 7, left and right cross line patterns are shown only in cyan.

(1) Horizontal line Lcm of left and right seven-character line pattern for each color
, L The difference a between the storage positions of Cz in the sub-scanning direction (paper feeding direction) corresponds to the inclination of the exposure means 3 of each color with respect to the photosensitive 1 column 1, and (2) the horizontal line L of the left cross line pattern.
The difference between the storage position in the sub-scanning direction of c1 and the reference position (for example, the cyan horizontal line storage position) corresponds to the positional deviation of the exposure means in the sub-scanning direction, and (3) the main scanning of the vertical line Lr1 of the left cross-hair pattern The difference C between the storage position in the direction and the reference position (for example, the cyan vertical line storage position) corresponds to the positional deviation of the exposure means in the main scanning direction.

Microcomputer Positional Displacement Calculation Process The microcomputer 33 in FIG. 5 uses the method explained in FIG. In addition to obtaining the tilt, the positional deviation c of the exposure means in the sub-scanning direction and the main scanning direction is calculated.

Adjustment of the inclination of the exposure means in each recording unit RUI to U4 is performed in advance using a correspondence table (α-
N table) 33d is prepared and the number of pulses Nc is determined according to the slope calculated for each color.

Find Nm, Ny, and Nb. Next, the obtained number of pulses is transmitted to the pulse motor drivers 24ac, 24cm, and 24a.
y.

Input to 24ab, pulse motor 24bc, 24b+
a.

Rotate 24, by, 24bb. This rotation causes the exposure means support to rotate, and the inclination of the exposure means is adjusted to zero. As a result, the exposure means of each recording unit is tilted, and the recording state is changed to C, M, Y, B in FIG. 8(a).
Even if it is tilted as shown in FIG. 8(b), the tilt is adjusted to zero as shown in FIG. 8(b).

The positional deviation in the sub-scanning direction of the exposure means in each recording unit RUI to U4 is determined by the positional deviation b and the exposure timing (
Recording timing) T correspondence table (b-T table)
33e is prepared, and the exposure timings Tc, Tm, Ty,
Determine Tb and set the exposure timing adjustment register 34c,
34 m, 34 y.

34. Store in b. Next, the positional shift in the sub-scanning direction is adjusted by advancing or delaying the exposure time L during actual recording by the exposure timing.

As a result, even if there is a positional shift in the sub-scanning direction as shown in FIG. 8(b), the recording positions will match as shown in FIG. 8(c).

The positional deviation C of the exposure means in each recording unit l-RU 1 to U4 in the main scanning direction is determined by the main scanning position adjustment registers 35 c , 35 m , 35 y , 35 , respectively.
b. Then, when recording, it is 1 by 1 position deviation.
Adjustment is made by shifting the correspondence between the line image dot positions and the exposure elements constituting the exposure means.

FIG. 9 is an explanatory diagram of the positional deviation correction method in the main scanning direction, in which 3a is an exposure element for one line constituting the exposure means;
b is a line buffer that stores image data for one line, and the number of bits of the line buffer and the number of exposure elements match, and there are MQ, Mr. are placed one by one. If there is no positional shift in the main scanning direction, one line of image data is stored in the regular line buffer positions b□ to bn indicated by diagonal lines in FIG. 9(b), and the Dr. -1
If a positional shift occurs, one line of image data is stored in the line buffer position indicated by diagonal lines in FIG. 9(c), and if a positional shift occurs by DQ to the left in the main scanning direction, , one line of image data is stored in the line buffer position indicated by diagonal lines in FIG. 9(d). As a result, during recording, the exposure element corresponding to black ('I'') of the image data in the line buffer 3b emits light to perform recording, and the positional deviation in the main scanning direction is corrected.

FIG. 10 of 1 of the hand position adjustment section shows a first embodiment of the exposure means position adjustment section,
This is an example in which the exposure means support is rotated by screw rotation.
1 is a photosensitive drum, 3 is an exposure means such as ED array, 2
4-b is a pulse motor fixed to the printer body, 2
4c is an exposure means support that supports the exposure means 3 in opposition along the direction of the rotation axis of the photosensitive tram 1; 24. d is a ball screw threadably engaged with the tip of the exposure means support, and 24e is a support metal fitting that supports the exposure means support 24c, or in other words, the exposure means 3, rotatably around the fixing pin 24f. The number of pulses N corresponding to the inclination angle of the exposure means 3 is determined, and the pulse motor 24. When b rotates, the ball screw rotates, and the exposure means support 24 engages with the ball screw.
c rotates in accordance with the motor rotation direction, and is adjusted so that the inclination angle becomes zero.

2. Example of Exposure Means Position Adjustment Section FIG. 11 shows a second embodiment of the exposure means position adjustment section.
This is an example in which the exposure means support is rotated by the rotation of a cam, where 1 is a photosensitive drum, 3 is an exposure means such as an LED array, and 2
4b is a pulse motor fixed to the printer body, 24c
24d' is a cam that engages with the tip of the exposure means support, and 24'' supports the exposure means 3 in the direction of arrow A. The spring 24e biasing the exposure means 24c is a support metal fitting that supports the exposure means 3 rotatably around the fixing pin 24.f.

When the number N of pulses corresponding to the inclination angle of the exposure means 3 is determined and the pulse motor 24b is rotated by the number of pulses, the cam 24d
' is rotated, and the exposure means support 24c engaged with the cam is rotated in accordance with the rotational direction of the motor, so that the inclination angle of the exposure means is adjusted to zero.

(b) Positional deviation adjustment operation Next, the positional deviation adjustment process of the exposure means will be explained for an electrophotographic color printer.

Fig. 12 is a flowchart for explaining the overall operation of positional deviation adjustment. When the position adjustment mode switch provided on the operation panel 36 (see Fig. 5) of the printer is operated, or when the number of recorded sheets N exceeds the set number Ns, the recording control section 37 (see Fig. 5) activates the exposure means. The position adjustment mode is entered (steps 101 and 102).

When the position adjustment mode is entered, the recording control unit 37 inputs the measurement pattern (crosshair pattern) image to the recording units RU1 to RU4 of each color, and as shown in FIG.
Cyan, magenta, yellow, and black cross-hair patterns CRPc, CRPm, CRPy, and CRPb are recorded on both sides of 2 (step 103).

Thereafter, the microcomputer 33 executes a positional deviation measurement routine to be described later, measures the crosshair pattern position of each color, and determines the inclination a of the exposure means in each recording unit 1, the positional deviation b in the sub-scanning direction, and the positional deviation b in the main scanning direction. Positional deviation C
is measured (step 104).

When the measurement routine is completed, a tilt and positional deviation adjustment routine to be described later is executed to adjust the tilt of the exposure means in each recording unit, positional deviation in the sub-scanning direction, and positional deviation in the main scanning direction.Step 105), Adjustment. After that, the recording units R, U1 to RTJ 4 record the crosshair pattern on the recording paper 12 again (step 106), and the positional deviation is measured by the positional deviation measurement routine (step 107).

Next, it is checked whether the inclination and positional deviation are below the set tolerance values (step 1.08), and if they are below the tolerance values, the position adjustment mode is terminated and the normal recordable state is entered thereafter.

However, if it is not below the allowable value, check whether the number of adjustments has exceeded the set number (step 109).
If the set number of times has not been reached, the adjustment processing from step 105 onwards is repeated.

If the positional deviation and inclination do not fall below the allowable values even after the adjustment is performed more than the set number of times, it is determined that some kind of failure has occurred in the printer. Step 10) Display an error message and notify the −1− device such as the host to that effect.
, exit the position adjustment mode and stop recording.

position (dtu) FIG. 13 is a flowchart of the positional deviation measurement routine.

A crosshair pattern of each color is recorded on the recording paper 12 by each of the recording units l-RU1 to RU4, and at the timing when the cyan seven-character line pattern comes under the position measuring section 22, the microcomputer 33 controls the driver 22d. Make the red light emitting diode 22r (see Figure 3) emit light (step 20])
.

Then, while the red light emitting diode is emitting light, the CC
The D line sensor 22s reads the cyan cross line pattern images recorded on both sides of the recording paper 12 and sends the data to the microcomputer 33.
After storing, the memory address is incremented (steps 202 to 204).

Next, it is checked whether the crosshair pattern has been read for the required length (a predetermined number of lines) in the sub-scanning direction (step 205), and if it has not been read, the light emitting diode continues to be lit until it is read.

Upon completion of reading a predetermined number of lines, the crosshair patterns on both sides of the recording paper are stored in the cyan memory 33c, as shown in FIG.

When the storage process is completed, the microcomputer 33 detects the main scanning direction storage position (referred to as coordinates) of the vertical line Lr in the left crosshair pattern and saves it to a specific memory address (save area) (steps 206, 207).

Next, the microcomputer 33 detects the sub-scanning direction coordinates of the horizontal line LCI in the left-hand cross-hair pattern and the horizontal line Lc2 in the right-hand cross-hair pattern, and calculates the difference as a slope (steps 208 to 210), and calculates the calculation result (tilt data). Save the left horizontal line position in the save area (step 21
1).

Thereafter, the microcomputer 33 similarly measures the position of the magenta cross-hair pattern by emitting light from the green light-emitting diode 22g at the timing when the magenta cross-hair pattern comes under the position measuring section 22 (step 212.21.3). Next, at the timing when the yellow cross-hair pattern comes under the position measuring unit 22, the blue light emitting diode 22b emits light to open the yellow cross-hair pattern position in step 214.2.
15) At the end, the black crosshair pattern is the position measurement unit 22.
When the red light emitting diode 22 comes to the bottom, the red light emitting diode 22
r is emitted to measure the position of the black crosshair pattern (steps 216 and 217), and the measurement process ends.

Place-” Breast treatment- FIG. 14 is a flowchart of the position adjustment routine.

When adjusting the position, the microcomputer 33 takes out the tilt data a of the cyan exposure means from the save area (step 3).
01), the number of pulses corresponding to the inclination is determined from the a-N table 33d (step 3o2), and the position adjustment pulse motor 24. bc is rotated by the number of pulses to adjust the inclination of the cyan exposure means (step 303). ...After the above tilt adjustment, the microcomputer 33 reads out the cyan horizontal line coordinates from the save area (step 304), calculates the difference between the horizontal line coordinates and the reference coordinates (recording designated coordinates), and uses the exposure means in the sub-scanning direction. Find the positional deviation b (step 305)
, the exposure timing data corresponding to the positional deviation is obtained from the b-T table 33e, and the exposure timing adjustment register 3
4c (step 306). As a result, the n-light timing is advanced or delayed in accordance with the positional deviation in the sub-scanning direction during recording, and the positional deviation in the sub-scanning direction is adjusted.

Thereafter, the microcomputer 33 reads the cyan ordinate from the save area (step 307), calculates the difference between the vertical coordinate and the reference coordinate (recording designated coordinate), and calculates the positional deviation C of the exposure means in the main scanning direction. is calculated (step 308) and stored in the main scanning position adjustment register 35c (step 30).
9). As a result, the position in the line buffer where one line of images is stored is shifted by the positional deviation, and the recording position in the main scanning direction is adjusted.

Thereafter, similar position adjustment processing is performed for magenta, yellow, and black (step 310).

(c) Other Embodiments of the Present Invention Although the present invention has been described above in the case where it is applied to a color printer, the present invention can also be applied to the position adjustment of the exposure means when recording in one color.

Further, in the above description, the position adjustment is performed by operating a switch or when the number of recorded sheets reaches a predetermined number, but it can also be configured to be performed every predetermined operation time.

Furthermore, although the case where an LED array is used in the exposure section has been described below, the present invention is not limited to such a case, but can be similarly applied to a case where a laser optical system is used in the exposure section. However, in this case, the entire laser optical system unit is placed on a support whose one end is movable, and the position of the support is adjusted by moving the ends of the support with a motor.
Position adjustment similar to that for arrays is possible.

In addition, the exposure means is not limited to the T=ED array.
Any device that can control the lighting of the dots is fine, for example, E.
Similar positional control is possible using an I' array.

Hereinafter, the present invention has been described with reference to examples, but the present invention can be modified in various ways according to the gist of the present invention as described in the claims, and the present invention does not exclude these modifications.

[Effects of the Invention] According to the present invention, since the inclination and positional deviation of the exposure means are measured and the position is automatically adjusted so that these become zero, positional deviations due to aging of the printer or environmental changes are avoided. It is possible to provide an electrophotographic printer that is free from color shift and color shift.

In addition, since adjustments can be made automatically after replacing the exposure section or replacing the drum, the down time of the apparatus can be shortened and maintenance services can be improved.

Further, since there is no need to make adjustments during assembly, and adjustments can be made easily and in a short time after the printer body is assembled, it is possible to reduce the number of assembly and adjustment steps.

In addition, the motor is rotated according to the inclination of the exposure means, and the rotation of the motor rotates the ball screw or cam to rotate the exposure means support, thereby reducing the inclination to zero. can be easily configured.

Furthermore, since it is configured to allow periodic position adjustment,
Records can always be recorded without positional or color shifts. Further, if the positional deviation does not become less than the allowable value no matter how many times the error is displayed, the operator can be immediately warned.

[Brief explanation of the drawing]

Fig. 11 is an explanatory diagram of the principle of the present invention; Fig. 2 is an explanatory diagram of the arrangement of the position measuring unit in one embodiment; =32 Fig. 3 is a configuration diagram of the position measuring unit; Fig. 4 is a crosshair pattern and position. Figure 5 is a configuration diagram of the exposure means position control unit in one embodiment configuration, Figure 6 is a signal waveform diagram of each part for explaining operation, and Figure 7 is a diagram showing the storage position of the crosshair pattern. Diagram 1 to explain the relationship between tilt and positional deviation. 1) Figure 6 is an explanatory diagram of tilt and positional deviation adjustment, No. 91 is an explanatory diagram of a method of adjusting positional deviation in the main scanning direction, Figure 10 is a first embodiment of the exposure means position adjustment section, and Figure 1 is an illustration of the exposure means Embodiment 2 of the position adjustment section, FIG. 12 is a flowchart explaining the overall operation of positional deviation adjustment, and FIG. 3 is a flowchart of a positional deviation measurement routine. Fig. 14 is a flowchart of the position adjustment routine, Fig. 15 is a configuration diagram of a conventional high-speed LED color printer, Fig. 16 is an external view of the LED head (LED array) that is the exposure means, and Fig. 17 is the LED array. It is a block diagram of a chip and a driver IC chip. ] ・ 3 ・ 2" ・Photosensitive 1 column・Exposure means・・Pattern generation section・・Position measurement section・・Position deviation calculation section・・Exposure means position adjustment section 2゛9 people

Claims (9)

[Claims] (1) In an electrophotographic printer that uses an exposure device to expose a photosensitive drum based on image data to be recorded to form an electrostatic latent image and performs recording using an electrophotographic process, in a position adjustment mode of the exposure device, a predetermined A measurement pattern generation section that generates a measurement pattern and records it on a storage medium, a position measurement section that measures the position of the measurement pattern recorded on the storage medium, and a position measurement section that measures the positional deviation of the exposure means based on the measured measurement pattern position. 1. An electrophotographic printer comprising: a positional deviation calculation section that calculates a positional deviation; and an exposure means position adjustment section that adjusts a positional deviation of an exposure means. (2) The measurement pattern is formed of horizontal lines and vertical lines, the position measurement section measures the left and right end positions of the horizontal lines in the sub-scanning direction, which is the paper feeding direction, and the positional deviation calculation section measures the positions of the left and right ends of the horizontal lines in the sub-scanning direction, which is the paper feeding direction. The electrophotographic printer according to claim 1, wherein the inclination of the exposure means is calculated based on the difference between the left end position and the right end position of the horizontal line, and the exposure means position adjustment section adjusts the inclination of the exposure means so that the inclination becomes zero. . (3) An exposure timing control section that controls the exposure timing of the exposure means for a time corresponding to the amount of positional deviation in the sub-scanning direction, and the positional deviation calculation section is configured to calculate the left end position or right end position of the horizontal line of the crosshair pattern and the reference position. 3. The electrophotographic printer according to claim 2, wherein the positional deviation in the sub-scanning direction is calculated based on the difference between the two positions. (4) A main-scanning direction positional deviation adjustment section that changes the exposure position of the exposure means by an amount corresponding to the amount of positional deviation in the main-scanning direction is provided, the position measurement section measures a vertical line position, and the positional deviation calculation section 3. The electrophotographic printer according to claim 2, wherein the positional deviation in the main scanning direction is calculated based on the difference between the vertical line position of the crosshair pattern and the reference position. (5) The electrophotographic printer according to claim 1, wherein a recording unit is provided for each of a plurality of color reference colors, and the positional deviation adjustment is performed in each recording unit. (6) The exposure means position adjustment section has a motor attached to the printer body, a screw rotationally driven by the motor, and an exposure means support section movable by rotation of the screw. 2. The electrophotographic printer according to 2. (7) The exposure means position adjustment section has a motor attached to the printer main body, a cam rotationally driven by the motor, and an exposure means support section movable by rotation of the cam. 2. The electrophotographic printer according to 2. (8) The electrophotographic printer according to claim 1, wherein an error is displayed if the amount of positional deviation does not fall below a tolerance value even after performing the position adjustment and the recording operation after the position adjustment a predetermined number of times or more. (9) The electrophotographic printer according to claim 1, wherein the position adjustment is performed every time a predetermined number of sheets are recorded.