JP2001063133A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent positional shift in the θdirection when a print head has an angular error without increasing the processing amount of a print head controller or the transmission amount of data. SOLUTION: Two strobe signals (STROBE1, STROBE2) and a plurality of strobe select circuits 50 are provided. The two strobe signals have a phase difference 1/2t equal to one half of head line period t. The strobe select circuit 50 (50a, 50b) is provided for every four NAND gates 47 and selects any one of two strobe signals. Since print results by STROBE1, STROBE2 are shifted by one half of head line pitch d, level difference is suppressed in the print results.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-color (color) image recording apparatus using a so-called tandem system, and more particularly to an image recording apparatus for correcting an angle error of a print head.

[0002]

2. Description of the Related Art As a multicolor image recording apparatus for performing color printing, for example, an image forming unit for performing printing of yellow (Y), magenta (M), cyan (C), and black (BK) is provided. 2. Description of the Related Art A so-called tandem-type multicolor image recording apparatus that performs printing on paper by sequentially performing printing is known. In this type of multicolor image recording apparatus, yellow (Y), magenta (M), cyan (C), black (B
Since the toner of K) is sequentially transferred to a sheet to form a color image, the arrangement accuracy of the image forming units of each color is important. That is, if the arrangement accuracy of the image forming units for each color is poor, the formed image will be misaligned, resulting in an image with poor print quality.

[0003] For this reason, various methods have conventionally been used to prevent image displacement for each color. For example, Japanese Patent Application No. 08-34 filed earlier by the same applicant.
In the invention of 3974, the rotation direction of the photoconductor drum (hereinafter, referred to as a sub-scanning direction), the direction orthogonal to the rotation direction of the photoconductor drum (hereinafter, referred to as a main scanning direction), and the print head have an angular error. In this case, each positional deviation with respect to the θ direction is prevented.

[0004] To prevent displacement in the sub-scanning direction, the output timing of a vertical synchronizing signal for controlling synchronization in the sub-scanning direction is changed, thereby changing the exposure timing of the photosensitive drum to change each color image on paper. (Yellow (Y), magenta (M), cyan (C), black (BK)) in the sub-scanning direction.

In order to prevent the displacement in the main scanning direction, when the LED elements of the print head emit light, when one line of video data is n dots and the number of dots of the print head is m dots, printing is performed on paper. The respective centers of the heads are aligned, and (mn) /
By inserting non-emission data of 2 dots at the beginning and end of n-dot data, which is video data for one line, the printing dots are shifted to the left and right with respect to the center of the paper. , By adjusting the printing position in the main scanning direction.

Further, when the print head has an angle error, prevention of displacement in the θ direction is as follows. FIG. 14 is a diagram showing the displacement of the print head. In the figure, the actual position of the print head 100 shown by the solid line is shifted from the regular head position of the print head 100 'shown by the broken line. In such a case, by correcting the data output to the print head by rearranging the data vertically, θ
Direction misalignment is prevented.

FIG. 15 shows a print result of one line after correction. As shown in the figure, when the print result of one line is viewed, the displacement in the θ direction is prevented. In this case, since the mechanical position of the print head is kept fixed and the misalignment is prevented by rearranging the data, a discontinuous portion occurs at the position indicated by the reference symbol D in FIG. Since a level difference occurs, it is necessary to reduce the level difference to such an extent that it cannot be visually identified.

Therefore, in order to make the level difference inconspicuous, one original line in the main scanning direction is divided into a plurality of main scanning lines, and these angles are corrected. here,
As an example, a description will be given of the prevention of displacement in the θ direction when the light emission size of the light emitting portion of the print head is reduced to 1/3 in the sub-scanning direction.

FIG. 16 is a diagram showing the light emission size of the light emitting section. FIG. 3A shows a normal light emission size. On the other hand, FIG. 6B shows the light emission size reduced to one third of the normal size in the sub-scanning direction. However, in the light emission size shown in FIG. 3A, an electrostatic latent image for one dot was formed on the photosensitive drum by one exposure, but it was reduced to 1/3 of the normal size shown in FIG. In the case of a small light emission size, three exposures are required because an electrostatic latent image for one dot cannot be formed by one exposure.

FIG. 17 is a view of a normal print state viewed from a print head having an angle error. As shown in the figure,
By dividing one line of data into a plurality of parts and changing the timing of outputting the data to the print head, an image close to a normal print state is obtained even with a print head having an angle error. As described above, by outputting data of a plurality of lines as shown in FIG. 18 to the print head at a certain exposure timing with respect to the print head having an angle error rising to the right, the angle error can be reduced. Corrections can be made.

[0011]

However, as described above, when the positional deviation in the θ direction is prevented when the print head has an angular error, the step indicated by reference symbol D in FIG. 15 is made small and inconspicuous. In addition, it is necessary to reduce the light emission size of the light emitting unit as much as possible. For example, when one original line in the main scanning direction is divided into four main scanning lines, one original line in the main scanning direction is 600 [dp].
i], the divided main scanning line is 2400 [dp
i], and reducing the emission size increases the amount of data sent to the print head.
Therefore, there arises a problem that the processing amount and the data transmission amount of the head control device increase.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to increase the processing amount and the data transmission amount of the print head controller without increasing the angle in the θ direction when the print head has an angular error. It is an object of the present invention to provide an image recording apparatus which can prevent the positional deviation of the image recording apparatus.

The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus that corrects an image position.

[0014]

According to an aspect of the present invention, there is provided an image forming apparatus for correcting an angle error of a print head by rearranging print data to be output to the print head. Provided is an image forming apparatus having a plurality of strobe signals for instructing light emission timing of an element and a plurality of strobe selecting means for selecting one of the plurality of strobe signals for each of one or a plurality of storage elements. Can be achieved by:

With this configuration, the printing position is different for each of one or a plurality of storage elements during one period of the main scanning line pitch by the emission timing of the plurality of strobe signals. It is possible to reduce the step due to the correction.

According to a second aspect of the present invention, there is provided an image forming apparatus for correcting an angle error of a print head by rearranging print data output to a print head which is a dynamic head. A strobe signal for instructing a plurality of light emission timings during one period of the pitch, a storage unit for storing the rearranged print data, and selectively storing the print data from the storage unit in accordance with the plurality of light emission timings. The present invention can be attained by providing an image forming apparatus having input means for inputting data to the print head, and indicating means for indicating a light emitting element position of print data input by the input means.

With this configuration, it is possible to instruct a plurality of light emission timings during one cycle of the main scanning line pitch, and to selectively print corresponding print data in accordance with the light emission timing. By inputting to the light emitting element position, it is possible to reduce the step due to the correction of the angle error, and it is applicable to a print head which is a dynamic head having only a small capacity data buffer.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is an overall configuration diagram of a multicolor image recording apparatus of the present embodiment. Note that the multicolor image recording apparatus used in the description of the present embodiment is a so-called tandem type color printer. In FIG. 1, a color printer 1 includes a paper supply / transport mechanism 2, a plurality of image forming units 3, and a fixing device 4. Paper supply / transport mechanism 2
Is composed of a paper feed cassette 5 loaded with paper P and a paper transport system 6. Further, the paper transport system 6 sets a paper feed roller 8 for transporting the paper P from the paper feed cassette 5, a paper transport path 7 for transporting the paper P transported by the paper feed roller 8, and a paper position matching the toner image. A standby roll 9 for feeding the paper, a driving roll 10, 11 driven by a motor (not shown), and a transport belt 12 rotated by the driving rolls 10, 11.

The sheet P conveyed from the sheet cassette 5 to the sheet transport path 7 by the rotation of the sheet feeding roller 8 is sent to the standby roll 9 by the rotation of the sheet feeding roller 8, and is formed on a photosensitive drum described later. It moves on the conveyor belt 12 at a timing coincident with the toner image to be formed. Note that the charge removing device 13 is a device that removes electric charges remaining on the transport belt 12.

While the paper P moves on the transport belt 12, each of the image forming units 15,
The toner of each color is transferred by 16, 17, and 18, and color transfer is performed on the paper P. Thereafter, a heat fixing process is performed by the fixing device 4, and the sheet P is carried out of the apparatus.

The fixing device 4 comprises a heat roll 4a and a pressure roll 4b. While the paper P is nipped and conveyed between the heat roll 4a and the pressure roll 4b, for example, a plurality of colors transferred to the paper P are transferred. The toner is melted and printed on the paper P.

On the other hand, as described above, the image forming unit 3 includes yellow (Y), magenta (M), cyan (C),
Four black (BK) image forming units 15 to 18
And are arranged in this order. Yellow (Y), magenta (M), and cyan (C) are image forming units 15 to 17 that perform color printing by subtractive color mixing, and a black (BK) image forming unit 18 is an image forming unit that is used for monochrome printing. It is.

Each of the image forming units 15 to 18 has exactly the same configuration except for the color of the developer contained in the developing container.
In this configuration, a developing device and a transfer device are sequentially arranged. Where 4
The configuration will be described by taking the image forming unit 15 for yellow as an example of the image forming units 15 to 18 as a representative. The peripheral surface of the photoconductor drum 20 is made of, for example, an organic photoconductive material. In the vicinity of the peripheral surface of the photoconductor drum 20, a charger 21, a print head 22, and a developing roll 23 '(developing device 2)
3), transfer devices 24 are sequentially arranged. The photoreceptor drum 20 rotates in the direction of the arrow, and first charges the peripheral surface of the photoreceptor drum 20 uniformly by applying a charge from the charger 21.
Next, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 20 by optical writing based on print information from the print head 22,
A toner image is formed by a developing process using the developing roller 23 '. At this time, the toner image formed on the peripheral surface of the photosensitive drum 20 is based on yellow (Y) toner stored in the developing container 23. The toner image thus formed on the peripheral surface of the photosensitive drum 20 reaches the position of the transfer unit 24 with the rotation of the photosensitive drum 20 in the direction of the arrow, and is transported on the transport belt 12 by the transfer unit 24. Is transferred to the paper P to be printed.

The toner image transferred onto the upper surface of the sheet P is conveyed in the direction of the arrow along with the movement of the conveyor belt 12, and is yellow (Y) by another image forming unit 16, 17 having the same configuration as described above. Magenta (M) and cyan (C) toners are sequentially transferred together with the toner,
Color printing by subtractive color mixture is performed. For example, if the print image is blue, the magenta (M) toner is transferred from the image forming unit 16 to the paper P based on the principle of subtractive color mixing, and then the cyan (C) toner is transferred from the image forming unit 17 to the paper P. Transfer to P to realize a blue image. Also,
For example, if the print image is red, the yellow (Y) toner is transferred from the developing unit 15 to the paper P, and then the magenta (M) toner is transferred from the image forming unit 16 to the paper P. To achieve.

FIG. 2 is a system configuration diagram of the color printer 1 having the above configuration. The color printer 1 includes a print control unit 26, an engine control unit 27, a PP
It comprises a C color engine unit 28. The print control unit 26 analyzes the print data output from the host computer 29, and
(Note that the print head 22Y is for yellow (Y), the print head 22M is for magenta (M),
Create dot pattern data (video data) to be output to C (for cyan (C) and print head 22BK for black).

The engine control section 27 comprises a CPU and the like, and a specific system diagram is shown in FIG. The engine control unit 27 includes a CPU 30, a ROM 31,
RAM 32, EEPROM 33, video I / F control unit 3
4, a head control unit 35, a correction control unit 36, and an input / output control unit 37. The CPU 30 performs system control of the entire color printer 1 of the present embodiment, and performs control according to a program stored in the ROM 31. Also, RA
M32 stores data generated during the control processing of the CPU 30. An operation panel 38 is connected to the CPU 30, and a key operation signal is output from the operation panel 38 to the CPU 30.

The EEPROM 33 stores data necessary for various processes. The video data output from the print control unit 26 is input to the video I / F control unit 34, and the input video data is output to the video I / F.
The data is output to the head control unit 35 under the control of the control unit 34. The video I / F control unit 34 transmits and receives various signals to and from the print control unit 26 in addition to the above-described video data.

The head control unit 35 is a video I / F control unit 3
4 is input to the image forming units 15 to
18 is a circuit for controlling the output to the print head 22 provided in the printer 18; yellow (Y) video data is output to the print head 22Y; magenta (M) video data is output to the print head 22M; The video data of (C) is output to the print head 22C, and the video data of black (BK) is output to the print head 22BK. These print heads 22 (22Y and the like) are disposed in the image forming units 15 to 18 as described above, and constitute a part of the PPC color engine unit 28 in FIGS.

FIG. 4 shows a drive circuit 2 in the print head 22.
FIG. 2C is a circuit diagram of the print heads 22Y, 22M, and 22 '.
Both C and 22BK have the same configuration. As shown in FIG.
5. Latch circuit 46, NAND gate (NAND gate)
47, a driving transistor 48, and a strobe signal selection circuit 50, and drives the LED element 49 according to a signal output from the driving transistor 48. The shift register 45 is capable of serially inputting video data for one line, and inputs print data (HDATA) for one line in synchronization with a clock signal (CLK). The latch circuit 46 is a circuit that latches video data input to the shift register 45 in synchronization with a latch signal (LATCH). One strobe selection circuit 50 is provided for each of the four light emitting elements 49, and based on a strobe control signal input from the head control unit 35, as a strobe signal for instructing light emission timing, is STROBE1 or STROBE1.
The print data latched by the latch circuit 46 is a circuit for selecting the ROBE2.
Is output to the NAND gate 47 in synchronization with the selected strobe signal. The strobe control signal is control data generated by the head control unit 35 in accordance with the correction angle, and is stored in a memory in the strobe selection circuit 50.

The print data output to the NAND gate 47 is, for example, a high (H) signal only for dots to be printed, and outputs a high (H) or low (L) signal to the drive transistor 48 from the output of the corresponding NAND gate 47. Then, the corresponding LED element 49 is driven.

The above configuration is the same for each of the print heads 22Y to 22C for yellow (Y), magenta (M), cyan (C), and black (BK), and prints based on each video data. Head 22 (LED
Optical writing is performed from the element 49) to the photosensitive drum 20.

It should be noted that the PPC color engine unit 28 and the CP other than the video data and signals related to head control described above are used.
The transmission and reception of signals between U30 is performed via the input / output control unit 37 described above.

On the other hand, the correction control section 36 connected to the CPU 30 is a circuit used when correcting video data. FIG. 5 shows a circuit of the correction control unit 36. As shown in the drawing, the correction control unit 36 includes an input control unit 51, a plurality of line buffers 52 to 58, an output control unit 59, and an address control unit 60, and specific operations will be described later. .

Next, the adjustment of the print position when the print head has an angle error, which is a feature of the present invention, will be described. FIG. 6 is a diagram of the normal print state viewed from the print head 22 having an angle error. Now, the print head has an angular error as shown in FIG.

FIG. 7 is a diagram showing line data for performing angle correction on the print head 22 having an angle error rising to the right as shown in FIG. Here, as an example, the line data of the sixth line shown in FIG.
2 will be described based on the correction control unit shown in FIG.

First, the respective line data of the first to sixth lines are already stored at the addresses specified by the address control unit 60 of the line buffers 52 to 58 selected by the input control unit 51. When the line data of the first to sixth lines is stored, the seventh line buffer 58 stores
At the same time as the start of the storage of the line data of the line, the line data and the address specified by the output control unit 59 and the address control unit 60 are divided into six sections of the sections 1 to 6 shown in FIG. The data is output to the print head 22. First, the original data of the sixth line corresponding to the section 1 is output, and then the original data of the fifth line corresponding to the section 2 is output. Thus, 6
The data of the line is output to the print head 22, and the other lines are output in the same manner.

FIG. 8 shows a print result when the line data output to the print head is printed by the conventional angle correction method. This figure shows the printing result of the data of the sections 1 to 3 in the line data of the fifth to seventh lines shown in FIG. 7, and the other parts are omitted. As shown in the figure, the step of each line depends on the pitch d of the main scanning line. In the figure, the width of each section in the main scanning direction is indicated by 8 dots.

Therefore, in the present embodiment, the print head 22 has two strobe signals and a plurality of strobe selection circuits 50 as shown in FIG. The strobe selection circuit 50 outputs the two strobe signals (STROBE1 and STROBE2) output from the head control unit 35 to 4
A configuration is provided for selecting each dot unit.

FIG. 9 shows two strobe signals (STOR).
FIG. 3 is a diagram showing exposure timings of OBE1 and STROBE2). As shown in the figure, each strobe signal is
It becomes active (H) for a predetermined time in a cycle t (corresponding to the exposure time) corresponding to the main scanning head line pitch. However, STROBE2 is shifted in phase by a half cycle (１ ／ t) of the cycle t of STROBE1.

Next, a process until the line data is exposed will be described with reference to FIG. The data latched by the latch 46 is taken as an example of the line data of the fifth line shown in FIG. 7, and a description will be given of the process up to exposure of the original fifth line data corresponding to the section 1.

Now, based on the strobe control signal output from the head controller 35, the strobe selection circuit 50a
Selects STROBE1, and selects the strobe selection circuit 50.
b selects STROBE2. NAND Gate 4
The original line data of the fifth line (having a width of 8 dots in the main scanning direction) corresponding to the section 1 is output to 7a and 47b, and the left gate 4a of the line data in the main scanning direction is output to the NAND gate 47a. Dot data (hereinafter, 5
a), and data of four dots on the right side of the line data in the main scanning direction (hereinafter, referred to as 5b) are output to the NAND gate 47b.

According to the timing of each strobe signal, when STROBE1 is turned on (H), the NAND gate 47a is turned on and the data of 5a is exposed.
When ROBE2 is turned ON (H), the NAND gate 47b
Is turned on to expose the data of 5b. At this time, since the photosensitive drum to be exposed is rotating, the STROBE
1 and STROBE2 exposure timing deviation (1/2
Due to t), the printing results of 5a and 5b have a positional shift of 1/2 interval (1 / 2d) of the main scanning head line pitch d.

The printing result obtained in this way is shown in FIG.
Shown in As shown in the figure, the original line data of the fifth line, which corresponds to the section 1 of the line data of the fifth line, is divided into two parts, 5a and 5b, and has an interval of 1/2 of the main scanning head line pitch d. The image is printed with a positional deviation of (分 d). Similarly, the data is divided into two in the other sections of the line data of the fifth line. Data of section 2 is 4a and 4b, data of section 3 is 3a and 3b ... data of section 5 is 1a and 1b
Respectively. And 4a, 3a, 2a, 1
The data of a is exposed by STROBE1 and 4b, 3
The data b, 2b, and 1b are exposed by STROBE2, and each section is printed with a positional shift of 1/2 the main scanning head line pitch (1 / 2d) in each section.

By repeating this printing process, an image can be obtained in which the rightward downward angle correction with a small step is performed. As described above, in the present embodiment, the strobe signal is set to 2
The line data corresponding to one section of one line data is divided into two, and one of the data is divided in the sub-scanning direction by の of the line pitch. Can be shifted by the distance of, so that the step is half that of the conventional print result shown in FIG. 8, and the step can be made small and inconspicuous.

Further, since finer and smoother angle correction can be realized without reducing the light emission size of the print head as in the related art, the print data amount does not increase.
Also, the processing of the head control device is not complicated,
This makes it possible to prevent displacement in the θ direction when the print head has an angular error.

In this embodiment, the strobe signal is selectively controlled in units of four dots. However, the present invention is not limited to this. Any structure may be used as long as the strobe signal is selectively controlled in units of one or more dots. . Further, the number of strobe signals may be any number.

Further, in the present embodiment, when performing the left-downward angle correction, the positional relationship between the signal waveforms of STROBE1 and STORBE2 may be reversed. Further, although the data corresponding to one section of the line data is divided into two using two types of strobe signals, a configuration in which the data is divided into n using n types of strobes may be used.

The control data, which is a strobe control signal relating to the selection of the strobe signal, is stored in the memory of the strobe selection circuit. The control data may be input together with the print data from the head control unit every time. . By doing so, the size of the processing circuit can be reduced.

The memory for storing the control data may be volatile or non-volatile. In the case of a volatile memory, for example, the control data may be sent at the time of initialization.

It is desirable that the control unit of the strobe signal matches the control unit of the line buffer. <Second Embodiment> The first embodiment is applied to a so-called static head in which line data for one main scan is input to and held in a print head, and the photosensitive drum is exposed based on a strobe signal. It is an aspect.

On the other hand, a so-called dynamic head, which sequentially inputs and updates print data while exposing it, does not have a data buffer having a capacity to store one-line data, but has only a small data buffer.

For this reason, in the dynamic head, each section of line data for one main scan is divided into two by selecting one of two strobe signals, and the exposure is performed by shifting the phase of one of the divided data. Cannot be applied to the first embodiment. Since the data buffer of the dynamic head does not have the capacity to store one-line data, if the first embodiment is applied, the data in the data buffer is updated while waiting for the strobe signal, and correct printing is not performed. .

Therefore, in the second embodiment, print data corresponding to a plurality of strobe signals in the first embodiment is selectively transmitted from a line buffer, and exposure,
It is to be printed.

STROBE1 shown in the first embodiment
At a timing corresponding to the above, the corresponding print data in the line buffer is selectively input to the print head and exposed,
At a timing corresponding to ROBE2, corresponding print data in the line buffer is selectively input to and exposed to the print head. Other configurations are the same as those of the first embodiment.

Hereinafter, in order to make the description easy to understand, the line data to be printed is assumed to be the line data of the fifth line shown in FIG. I do.

FIG. 11 is a diagram showing exposure timing in this embodiment. As shown in the figure, STROBE1
Are input to the print head and exposed. Next, after 1/2 cycle (1 / 2t) of the main scanning line pitch cycle t, STROBE
5b and 4b, which are print data corresponding to 2 (2 group in FIG. 2)
Is input to the print head and exposed. Note that the exposure timing in the present embodiment is shown as L active.

The exposure result obtained in this manner is shown in FIG.
Shown in FIG. 5A shows the exposure result by the conventional method.
Input and exposure were performed in the order of a and b.

On the other hand, in this embodiment, the exposure results shown in FIGS. First, as shown in FIG. 5B, a group of print data 5a and 5b is input to and exposed to the print head, and then 1/1 of the main scanning line pitch period t.
After two cycles (1 / 2t), as shown in FIG.
The group print data 4a and 4b are input to the print head.
Expose.

As a result of the exposure shown in FIGS.
The printing result shown in FIG. 13 is obtained. As shown in the figure, the first group of data 5a and 4a, and the second group of data 5b and 4b are 1/1/2 of the main scanning line pitch d in the sub-scanning direction. It is printed with a shift of 2d.

As described above, according to the second embodiment, the first
At timings corresponding to a plurality of strobe signals in the embodiment, the corresponding print data is selectively transmitted from the line buffer, and is exposed and printed.
The same effect as that of the first embodiment can be obtained in the dynamic head.

In the second embodiment, since the print data is selectively inputted and exposed to the print head, the dot of the inputted print data is indicated by a signal line or the like. Here, the instruction may be a parallel signal indicating the dot position, a serial signal or an incremental pulse count.

Although the dot position is indicated by a signal line or the like, data indicating the dot exposure order may be stored in the print head. Further, in the present embodiment, the first group and the second group are shown in two divisions, but the present invention is not limited to this, and any division may be made.

In the first and second embodiments, print data may be binary or multi-level gradation control.

[0064]

As described above, according to the present invention,
Since finer and smoother angle correction can be realized without reducing the light emission size of the print head as in the past,
It is possible to prevent the displacement in the θ direction when the print head has an angular error without increasing the print data amount and without complicating the processing of the head control device.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a multicolor image recording apparatus.

FIG. 2 is a system configuration diagram of a color printer.

FIG. 3 is a system diagram of an engine control unit.

FIG. 4 is a circuit diagram of a drive circuit in the print head.

FIG. 5 is a circuit diagram of a correction control unit.

FIG. 6 is a diagram illustrating a normal print state viewed from a print head having an angle error.

FIG. 7 is a diagram showing line data for angle correction.

FIG. 8 is a diagram showing a printing result when printing is performed by a conventional angle correction method.

FIG. 9 is a diagram showing exposure timings of two strobe signals.

FIG. 10 is a diagram illustrating a print result according to the first embodiment.

FIG. 11 is a diagram showing exposure timing in the second embodiment.

12A and 12B are diagrams illustrating exposure results according to the second embodiment, FIG. 12A is a diagram illustrating exposure results by a conventional method, and FIG. 12B is a diagram illustrating exposure results of a group of print data; (C) is a diagram showing the exposure results of two groups of print data.

FIG. 13 is a diagram illustrating a print result according to the second embodiment.

FIG. 14 is a diagram illustrating a displacement of a print head.

FIG. 15 is a diagram showing a print result of one line after correction.

FIG. 16 is a diagram illustrating a light emitting size of a light emitting unit.

FIG. 17 is a view of a normal print state viewed from a print head having an angle error.

FIG. 18 is a diagram showing data of a plurality of lines.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color printer 2 Paper supply / transport mechanism 3 Image forming unit 4 Fixing device 5 Paper feed cassette 6 Paper transport system 7 Paper transport path 8 Paper feed roller 9 Standby roll 10, 11 Drive roll 12 Transport belt 13 Static eliminator 15-18 Images Forming unit 20 Photoreceptor drum 21 Charger 22 Print head 23 Developing unit 23 'Developing roll 24 Transfer unit 26 Print control unit 27 Engine control unit 28 PPC color engine unit 29 Host computer 30 CPU 31 ROM 32 RAM 33 EEPROM 33 Video I / F control unit 35 head control unit 36 correction control unit 37 input / output control unit 38 operation panel 45 shift register 46 latch 47 NAND gate 48 driving transistor 49 light emitting element 50 strobe selection circuit 51 input Head position D step of the control unit 52 to 58 line buffer 59 output controller 60 the address controller 100 the actual printhead position 100 'normal

Claims (2)

[Claims] An image forming apparatus for correcting an angle error of a print head by rearranging print data to be output to a print head, a plurality of strobe signals indicating light emission timing of a light emitting element, and one or more storage signals And a plurality of strobe selection means for selecting one of the plurality of strobe signals for each element. 2. An image forming apparatus which corrects an angle error of a print head by rearranging print data output to a print head which is a dynamic head, wherein a plurality of light emission timings are designated during one cycle of a main scanning line pitch. A strobe signal, a storage unit that stores the rearranged print data, and the print data in accordance with the plurality of light emission timings.
An image forming apparatus, comprising: input means for selectively inputting from the storage unit to the print head; and instruction means for specifying a light emitting element position of print data input by the input means.