JP2003341137A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To expose at a desired exposure line by correcting an exposure deviation resulting from the setting accuracy of an exposure head when plotting exposure is carried out by a dynamic lighting control. <P>SOLUTION: An imaging apparatus has the exposure head 15 with a plurality of light emitting arrays arranged in a main scanning direction, and images by dynamically controlling to turn on the emitting element arrays in accordance with image data and exposing an image carrier which moves at a predetermined scanning velocity in a sub scanning direction. An exposure head position detector 17 detects a deviation from a setting reference position preliminarily specified for the exposure head, and sends a deviation position detecting signal. A memory control circuit 14 selectively makes image data from image data of a line precedent by (K-1) lines (K is an integer not smaller than 2) to image data of the present line exposure data on the basis of a correction amount set corresponding to the deviation indicated by the position detecting signal. Light emitting arrays are dynamically controlled to be turned on in accordance with the exposure data. The exposure head position detector detects the deviation from the setting reference position in accordance with a light receiving amount distribution from a light emitting element set separately at the exposure head. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an exposure head having a plurality of light emitting arrays arranged in the main scanning direction, and dynamically controls the lighting of the plurality of light emitting arrays according to image data so that the light emitting arrays are arranged in the sub scanning direction. The present invention relates to an image forming apparatus that forms an image by drawing and exposing a moving image carrier (for example, a photosensitive drum).

[0002]

2. Description of the Related Art Generally, as an image forming apparatus, a plurality of light emitting arrays are arranged along a main scanning direction, and the light emitting arrays are controlled to be turned on in units of n (n is an integer) bit in accordance with image information (image data). It is known that the exposure image is formed on the generatrix of the photosensitive drum, which is an image carrier, to form an electrostatic latent image corresponding to the exposure image (so-called dynamic lighting control).

For example, the light emitting array is an LED array having a plurality of LED elements, and an image forming apparatus using such an LED array is called an LED printer, and an exposure head (LED print head) is formed by the plurality of LED arrays. ) Is configured. A plurality of LED arrays are arranged along the main scanning direction of the photoconductor drum, and the photoconductor drum is moved in the sub-scanning direction at a predetermined linear velocity (printing speed: mm / s).
The dynamic lighting control for sequentially lighting the LED array is performed while being driven by, and an electrostatic latent image corresponding to the image data is formed on the photosensitive drum.

In the dynamic lighting control as described above,
Since the photosensitive drum rotating at a predetermined printing speed is time-divisionally exposed by the LED array, the drawing exposure is performed obliquely in the LED array unit with respect to the arrangement direction of the LED array. There is. On the other hand, Japanese Patent Examination 6-14
In the pulse width control circuit described in Japanese Patent No. 610, in an LED printer using a plurality of LED arrays as a light source, variations in the central position of print pixels caused by rotation of a photoconductor drum are corrected to obtain print quality. It is described that it improves.

[0005]

As described above, Japanese Patent Publication No. 6-14610 corrects the variation in the center position of the print pixel caused by the rotation of the photosensitive drum, but the LED print head. When the LED is mounted on the LED printer (printer housing), if the mounting accuracy is not good (that is, it is not mounted accurately at the predetermined mounting position), the mounting accuracy will be improved even if the diagonal exposure can be corrected. As a result, a deviation occurs between the ideal exposure line and the actual exposure line. That is,
If the mounting accuracy is poor, the problem that the exposure is performed diagonally for each LED array cannot be solved. Therefore, when the LED print head is attached to the LED printer (printer housing), it is necessary to attach the LED print head at a predetermined attachment position with high accuracy.

Further, in a tandem type LED printer having a plurality of exposure heads (LED print heads) used as an exposure device, when mounting the LED print heads, the mounting accuracy between the LED print heads (each LED print head If the parallelism) is not good, even if the oblique exposure is corrected, the exposure line is shifted between the LED print heads, and a good image cannot be formed when a color image is formed. . Therefore, when mounting the LED print head, it is necessary to maintain good mounting accuracy. However, in order to improve the mounting accuracy, the work for mounting the LED print head must be performed extremely accurately, and the work amount increases, resulting in an increase in cost.

As described above, in the conventional LED printer,
Depending on the mounting accuracy of the LED print head, the actual exposure line may deviate from the ideal exposure line
There is a problem that the exposure is performed obliquely with respect to the array direction of the array.

An LED using the tandem system described above
In the printer, if the mounting accuracy of each LED print head is not good, the parallelism of the exposure line is shifted between the LED print heads, and it is difficult to obtain a desired image.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of performing exposure at a desired exposure line by correcting an exposure deviation caused by mounting accuracy of an exposure head when performing drawing exposure by dynamic lighting control. It is in.

[0010]

According to the present invention, an exposure head having a plurality of light emitting arrays arranged in the main scanning direction is provided, and the light emitting arrays are dynamically turned on and off according to image data, In an image forming apparatus for forming an image by exposing an image carrier moving in a scanning direction at a predetermined scanning speed, a deviation position detection signal is sent out by detecting a deviation from a mounting reference position defined in advance for the exposure head. Based on the position detection means and the correction amount set according to the deviation indicated by the position detection signal, from (K-1) line (K is an integer of 2 or more) previous image data to the image data of the current line. An image forming apparatus is provided, which comprises: lighting control means for selectively turning on image data as exposure data and dynamically controlling lighting of the light emitting array according to the exposure data. That.

In this way, the deviation between the mounting position of the exposure head and the predetermined mounting reference position is detected, and the image data is selectively used as the exposure data on the basis of the correction amount according to this deviation to form the light emitting array. Since the dynamic lighting control is performed, it is possible to correct the exposure deviation caused by the mounting accuracy and perform the exposure with a desired exposure line.

For example, the exposure head has first to mth
(M is an integer greater than or equal to 2) A light emitting array is provided and a light emitting element is provided, and when performing the dynamic lighting control in the order of the first to the mth light emitting arrays, the position detecting means outputs the light emitting element from the light emitting element. The deviation from the mounting reference position is detected according to the distribution of the amount of received light, and the lighting control means is calculated based on the position detection signal.
(M is any integer from 1 to m) Based on the amount of deviation between the exposure line and the ideal exposure line by the light emitting array, the Mth light emitting array is converted from the image data before the (K-1) th line to the above. Dynamic lighting control is performed according to any one of the image data up to the image data of the current line. By doing so, it is possible to correct the exposure deviation due to the mounting accuracy with a simple configuration.

Further, the position detecting means includes a plurality of light receiving elements arranged in the sub-scanning direction, and one of the light receiving elements is used as a reference light receiving element to receive the light receiving amount distribution and a predetermined light receiving amount distribution. The deviation from the attachment reference position is detected according to the deviation. By detecting the deviation from the mounting reference position in this way, the mounting position deviation of the print head can be easily detected.

The lighting control means selectively writes the first to Kth line buffer memories and the first to Kth line buffer memories in which image data is written for one line, respectively. While controlling the writing of the image data for one line to the write line buffer memory, one of the remaining line buffer memories is used as the read line buffer memory based on the position detection signal. And a memory control circuit for controlling read-out of image data for a line, and the lighting control means further outputs the image data read from the read line buffer memory between adjacent light emitting arrays. Sort and rearrange so that the sequence is reversed It has a data rearrangement circuit providing as an image data to the exposure head, and a light emitting array control circuit for dynamic lighting control said exposure head in accordance with the reordering image data. Then, the light emitting array control circuit dynamically controls lighting of the light emitting array according to the deviation from the mounting reference position. With this configuration, when the diagonal correction is performed using the dynamic lighting control, the driving circuit such as the LED driver can be integrated.

Further, according to the present invention, a plurality of exposure heads having a plurality of light emitting arrays arranged in the main scanning direction are provided,
In the image forming apparatus, which dynamically controls the light-emitting array for each of the exposure heads according to image data to expose an image carrier moving at a predetermined scanning speed in the sub-scanning direction to form an image, each of the exposure heads. Position detection means for detecting a deviation from a predetermined mounting reference position and sending out a position detection signal indicating the deviation for each of the exposure heads, and a correction set in accordance with the deviation indicated by the position detection signal. Based on the amount, image data from (K-1) line (K is an integer of 2 or more) previous image data to image data of the current line is selectively used as exposure data for each exposure head according to the exposure data. An image forming apparatus is provided which has a lighting control means for dynamically controlling the lighting of the light emitting array. By doing so, even if the mounting accuracy of the exposure heads is not precisely defined, the exposure lines can be corrected in parallel in the plurality of exposure heads.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. Incidentally, the dimensions of the components in the illustrated example,
Unless otherwise specified, the material, the shape, the relative arrangement, etc., are not intended to limit the scope of the present invention thereto, but are merely illustrative examples.

Referring to FIG. 1, an LED printer using the above-mentioned LED print head as an exposure head will be described here as an image forming apparatus. LE shown
The D printer is an image memory (Video Memory).
y) 11, buffer memory circuit 12, data rearrangement circuit 13, memory control circuit 14, exposure head (L
An ED print head) 15, an LED control circuit 16, and an exposure head position detection device (print head position detection device) 17 are provided.
As will be described later, the position shift of the LED print head 15 with respect to the mounting reference position at which the LED print head 15 should be mounted (hereinafter referred to as the amount of tilt) is detected by 7, and the memory control circuit 14
In accordance with the detection result (K-1: K is an integer of 2 or more), one of the image data from the image data of the previous line to the image data of the current line is selectively read out and controlled to perform drawing exposure. I do.

Image data (VDAT) is stored in the image memory 11.
A) is accumulated, and this image data is temporarily stored in the buffer memory circuit 12. Buffer memory circuit 12
Is the first to Kth line buffer memories 12-1 to 12
-K, and these line buffer memories 12-
1 to 12-K are controlled by the memory control circuit 14 to write image data for K lines, and read image data for one line as described later.

The image data (image data for one line) read out from the buffer memory circuit 12 is given to the data rearrangement circuit 13, where the data rearrangement is performed and the rearrangement is performed as described later. The image data is supplied to the LED print head 15 as replacement image data, and the LED print head 15 is driven and controlled by the LED control circuit 16. That is, dynamic lighting control is performed.

Referring to FIG. 2, the LED print head 15 includes an anode driver 21, a cathode driver 22, an LED exposure device 23, and an LED element 24. In the illustrated example, the LED exposure device 23. Is first to
The m-th (m is an integer of 2 or more) LED array 23-1 to 2
Have 3-m. Each LED array 23-1 to 23-
m is n (n is an integer of 2 or more) LED elements 25-1 to 25-1.
25-n, and the first to m-th LED arrays 23
-1 to 23-m are arranged along the main scanning direction.

The anode driver 21 has first to nth output terminals, and in the LED arrays 23-1 to 23-m, the first to nth output terminals are LED elements 25, respectively.
It is connected to the anode of -1 to 25-n. On the other hand, the cathode driver 22 has first to mth output terminals, and the first to mth output terminals are respectively the first to mth LEDs.
It is connected to the arrays 23-1 to 23-m. That is,
The first to mth output terminals of the cathode driver 22 are connected to the cathodes of the LED elements in the LED arrays 23-1 to 23-m, respectively.

N provided on the LED print head 15
A bit shift register (not shown) is provided with rearranged image data (VDATA), and an n-bit shift register shifts the rearranged image data bit by bit according to a clock signal provided from the LED control circuit 16. Meanwhile, rearranged image data is stored (this clock signal has a speed (frequency) that is an integral multiple of the linear speed of the photosensitive drum). The clock signal is also given to a clock counter (not shown), and the clock counter counts according to the clock signal, and when counting n bits, that is, at the falling edge of the n-th bit of the clock signal, the clock counter Outputs the count-up signal as a latch signal.

N provided in the LED print head 15
A bit data latch (not shown) latches the rearranged image data stored in the n-bit shift register when receiving the latch signal, that is, at the rising edge of the latch signal (hereinafter referred to as latch image data). When the rearranged image data is latched in the n-bit data latch, the anode driver 21 determines, for example, that the r-th bit (r is any integer from 1 to n) of the latched image data according to the latched image data. When it is at the high level (“1”), the built-in constant current switch is turned on, and the anode of the LED element 25-r in each of the LED arrays 23-1 to 23-m is passed through the r-th output terminal. Energize.

M provided on the LED print head 15
A horizontal write synchronizing signal is given to the bit shift register (not shown) from the LED control circuit 16, and m
The bit shift register is cleared by this horizontal write synchronization signal. Then, when the m-bit shift register is cleared, the cathode driver 22 goes into the disable state (inoperative state). On the other hand, the above-mentioned latch signal is given to the m-bit shift register, and the m-bit shift register enables the first output end of the cathode driver 22 at the first rising edge of the latch signal.

The latch signal is also given to the LED control circuit 16, and the LED control circuit 16 gives a strobe signal to the cathode driver 22 in synchronization with the latch signal.
Then, the cassette driver 22 is turned on when receiving the strobe signal. For example, the strobe signal is turned on while the strobe signal is at a low level, and the cathode side is energized. Here, first, since the first output end of the cathode driver 22 is enabled, the first LED array 23-1
The cathodes of the LED elements 25-1 to 25-n therein are energized, and at this time, the LED elements whose anodes are energized by the anode driver 21 emit light.

As described above, the first LED array 2
3-1 performs exposure, and the m-bit shift register receives the second signal from the cathode driver 22 at the second rising edge of the latch signal.
The output end of is enabled. The latch signal is also given to the LED control circuit 16,
Applies a strobe signal to the cathode driver 22 in synchronization with the latch signal. Then, the cassette driver 22 is turned on when receiving the strobe signal. Since the second output end of the cathode driver 22 is enabled, the LED elements 25-1 to 25-2 in the second LED array 23-1
The cathode of 5-n is energized, and at this time, the LED element whose anode is energized by the anode driver 21 emits light. Similarly, in synchronization with the 3rd to mth rising edges of the latch signal, the 3rd to mth LED arrays 23-3 to 23-m emit light to perform exposure.

In this way, the first to mth LED arrays 23-1 to 23- are synchronized with the rising edge of the latch signal.
By sequentially selecting m, an exposure line is formed on the photosensitive drum (not shown) according to the image data for one line.

Referring also to FIG. 3, the LED element 24 is LE
The LED element 24 is arranged on the opposite side of the fixed reference 15a of the D print head 15, and the LED element 24 indicates the mounting position of the LED print head 15. The print head position detection device 17 has a position detection C corresponding to the LED element 24.
A CD (not shown in Figure 2) is provided. Then, in consideration of the mounting accuracy of the LED print head 15, an odd number of CCD elements of 3 or more are arranged in the position detection CCD along the sub-scanning direction.

The position detection CCD receives the light (light emission) from the LED element 24. When the LED print head 15 is mounted at the mounting reference position, the position detecting CCD is
For example, the CCD element located in the middle of the plurality of CCD elements (hereinafter referred to as the central CCD element (reference CCD element)) is arranged so that the amount of received light is the largest. Now, assuming that the LED print head 15 is arranged at the mounting reference position, the light receiving amount of the central CCD element becomes the highest, so that the print head position detecting device 17 indicates that the print head position detecting signal indicates no tilt amount. A detection signal will be transmitted (hereinafter, this printhead detection signal is referred to as a first printhead detection signal). This first print head detection signal is applied to the memory control circuit 14. When the memory control circuit 14 receives the first print head detection signal, the memory control circuit 14 judges that there is no tilt amount, and performs buffer memory write / read control.

On the other hand, when the LED print head 15 is tilted (shifted) from the mounting reference position (that is, when there is a tilt amount), the LED element 24 also shifts from the mounting reference position according to the tilt amount. , Position detection C
In the CD, the CCD element that maximizes the amount of received light is determined according to the amount of tilt of the LED print head 15. That is, LE
The CCD element having the maximum received light amount deviates from the central CCD element in accordance with the tilt amount of the D print head 15 (in other words, as shown in FIG. 3B, the actual exposure line and the ideal exposure line are different from each other). Will be shifted).

As shown in FIG. 3B, in the print head position detecting device 17, the central CCD element is used as a reference point (origin) in advance, the sub-scanning direction is the x axis, and the received light amount is the y axis. A coordinate axis is defined as a coordinate point on the x-axis, and as described above, when the amount of received light at the origin becomes maximum, the print head position detection device 17 sends out a first print head detection signal. On the other hand, when the amount of received light at the coordinate point (x, 0) on the x-axis other than the origin becomes maximum, the print head position detection device 17 causes the print point position detecting device 17 to detect the coordinate point (x, 0).
The tilt direction and the tilt amount are obtained from the mounting reference position based on the above, and a print head detection signal indicating the tilt direction and the tilt amount is transmitted (hereinafter, this print head detection signal is referred to as the second
Of the print head detection signal). In this way
The print position detection device 17 detects the deviation from the mounting reference position according to the distribution of the amount of light received from the LED element 24. That is, one of the CCD elements is a reference CCD
As an element, the deviation from the mounting reference position is detected according to the deviation between the received light amount distribution and a predetermined received light amount distribution.

This second print head detection signal is given to the memory control circuit 14, and when the memory control circuit 14 receives the second print head detection signal, the above-mentioned buffer is considered in consideration of the tilt direction and the tilt amount. Memory write / read control is performed. That is, image data for K lines is written in the buffer memory circuit 12, and the tilt direction (plus or minus side with respect to the sub-scanning direction) and the tilt amount (hereinafter, tilt direction and tilt amount are generically referred to. The memory control circuit 14 selects one of the first to Kth line buffer memories 12-1 to 12-K according to the correction amount set in advance in the memory control circuit 14 based on The image data is read from and is supplied to the data rearrangement circuit 13. That is, in the memory control circuit 14, the LED element 24
Depending on the deviation between the mounting position and the mounting reference position indicated by, any one of the image data from the image data of (K-1) line before to the image data of the current line is selectively read out and controlled.

For example, with reference to a line buffer memory from which image data is read when the amount of tilt is zero (hereinafter referred to as a reference line buffer memory), a line from which image data should be read from the reference line buffer memory according to the correction amount. It will change the buffer memory. The reference line buffer memory is always the current line data. The correction amount is the fixed reference 15a described above.
From the side, the memory control circuit 14 determines the image data from any one of the first to Kth line buffer memories 12-1 to 12-K for each LED array. The image data from the image data before the (K-1) th line to the image data of the current line is selectively read out. In other words, the image data (different from each other) is written line by line in the first to Kth line buffer memories 12-1 to 12-K, and the memory control circuit 14 sets the first to Kth line buffers. The memories 12-1 to 12-K are selectively used as write line buffer memories to control writing of one line of image data to the write line buffer memories, and whichever of the remaining line buffer memories is to be used based on the position detection signal. One of them serves as the read line buffer memory, and the image data for one line is read out from the read line buffer memory and controlled.

As described above, the buffer memory circuit 1
The image data read from No. 2 is given to the data rearrangement circuit 13, where the data rearrangement is performed.
As described above, in the dynamic lighting control, since a plurality of LED arrays are caused to emit light in a time-division manner, one L
A plurality of LED arrays are driven by the ED driver (that is, the anode driver and the cathode driver). Therefore, a plurality of LED arrays (LED chips) 23-1 to
23-m and anode driver (anode driver IC)
21 and cathode driver (cathode driver IC) 2
When connecting the two, it is necessary to rearrange the image data so that the data arrangement is reversed between the LED arrays adjacent to each other because the wiring pattern is a so-called one-stroke writing wiring pattern.

Therefore, in the data rearrangement circuit 13, L
The image data is rearranged alternately in units of ED arrays (that is, in units of n bits). That is, for the odd-numbered LED arrays, the image data is "1, 2, 3, 4, ...
If the order is n ″, the image data for the even-numbered LED array is in the order of “n, ..., 4,3,2,1”. Sort the data and sort it as image data,
It is given to the LED print head 15. Then, as described above, the exposure is performed according to the rearranged image data.

In this way, the LED print head 1
In consideration of the amount of tilt from the mounting reference position of 5, the buffer memory writing / reading control is performed and the dynamic lighting control is performed. Therefore, when mounting the LED print head, it is not necessary to perform the mounting work carefully, As a result, it is possible to reduce the amount of work for mounting.

Here, referring to FIG. 4, in the LED printer using the tandem system, the above-mentioned position detecting CCD is provided for each LED print head. That is, the LED
Assuming that the printer has first to pth LED print heads 15-1 to 15-p (p is an integer of 2 or more), each LED print head 15-1 to 15-p is
The LED print heads 15-1 to 15-p are configured as described with reference to FIG. 2, and the LED elements 24-1 to 24-p are arranged on the opposite side of the fixed reference 15a. In addition, the print head position detection device 17 has an L
Position detecting CCDs 31-1 to 31-p are provided respectively corresponding to the ED elements 24-1 to 24-p. The position detection CCDs 31-1 to 31-p are provided with LEDs.
Considering the mounting accuracy of the print heads 15-1 to 15-p, q (q is an odd number of 3 or more) CCD elements 32-
1-32 to q are arranged in the sub-scanning direction.

As described above, each position detection CCD 31-
1 to 31-p are LED elements 24-1 to 24-p, respectively.
Receives light from. Then, the print head position detection device 17 obtains the received light amount distribution for each of the position detection CCDs 31-1 to 31-p and obtains each position detection CCD 31-1 to 31-p.
Each LED print head 1 is calculated by obtaining the tilt value for each 1-p.
The first or second print head position detection signal for 5-1 to 15-p is supplied to the memory control circuit 14. As described above, the memory control circuit 14 obtains the correction amount for each of the LED print heads 15-1 to 15-p, and controls the reading of the buffer memory circuit 12 according to the correction amount.

In the example shown in FIG. 4, the second LED print head 15-2 is tilted to the minus side (direction opposite to the sub-scanning direction), and the third LED print head 15-
3 is tilted to the plus side (sub scanning direction). Then, as described above, if the above-mentioned read-out control is performed on the second and third LED print heads 15-2 and 15-3, the exposure is performed along the ideal exposure line, and a color image is formed. A good image can be obtained without causing print misalignment.

In this way, in an LED printer having a plurality of LED print heads, a good image can be formed even if the mounting accuracy (parallelism) between the LED print heads is not strict, and the LED print heads can be formed. As a result, it is possible to reduce the amount of work required for mounting, so that the cost can be reduced. Then, by providing the line buffer memory for K lines and performing the read control as described above, the tilt correction is performed in the range of K lines between the LED print heads in units of 1 / n (dot / line). It can be performed, and the correction in the main scanning direction can be performed for each LED array.

[0041]

As described above, according to the present invention, in an exposure head having a plurality of light emitting arrays arranged in the main scanning direction, the light emitting array is dynamically turned on in accordance with image data, and the light emitting array is moved in the sub scanning direction. When an image is formed by exposing an image carrier that moves at a predetermined scanning speed, a deviation from an attachment reference position defined in advance for an exposure head is detected, and based on a correction amount set according to the deviation. (K-1) The image data from the image data before the line to the image data of the current line is selectively used as the exposure data, and the light-emitting array is dynamically lighted according to the exposure data. There is an effect that the exposure deviation can be corrected and the desired exposure line can be exposed.

In the present invention, when the dynamic lighting control is performed in the order of the first to mth light emitting arrays, the deviation from the mounting reference position is detected according to the distribution of the amount of light received from the light emitting elements separately provided in the exposure head. Then, the M-th light emitting array is calculated as (K-) based on the amount of deviation between the exposure line and the ideal exposure line by the M-th (M is an integer from 1 to m) light-emission array obtained according to the deviation. 1) Since the dynamic lighting control is performed according to any one of the image data from the image data before the line to the image data of the current line, it is possible to correct the exposure deviation due to the mounting accuracy with a simple configuration. The effect is that you can do it.

In the present invention, a plurality of light receiving elements arranged in the sub-scanning direction are used, and one of the light receiving elements is used as a reference light receiving element, and the light receiving amount distribution is attached according to the deviation between the predetermined light receiving amount distribution. Since the deviation from the reference position is detected, there is an effect that the deviation of the mounting position of the print head can be easily detected.

According to the present invention, the first to Kth line buffer memories in which the image data is written for one line are provided, and the image data is written in these line buffer memories and the read control is performed based on the position detection signal. Therefore, there is an effect that the exposure deviation caused by the mounting accuracy can be easily corrected.

In the present invention, the image data read from the read line buffer memory is rearranged so that the data array is reversed between the light emitting arrays adjacent to each other to form rearranged image data. There is an effect that a driving circuit such as a driver can be integrated.

Further, according to the present invention, in the image forming apparatus in which a plurality of exposure heads are arranged, a deviation from the mounting reference position defined for each exposure head is detected for each exposure head. Accordingly, since the dynamic lighting control is performed for each exposure head, there is an effect that the exposure lines can be corrected in parallel in a plurality of exposure heads even if the mounting accuracy of the exposure heads is not accurately specified. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a control system used in an image forming apparatus according to the present invention together with an exposure head (LED print head).

FIG. 2 is a diagram showing in detail the exposure head (LED print head) shown in FIG.

FIG. 3 is a diagram for explaining tilt amount correction with respect to a fixed reference.

FIG. 4 is a diagram for explaining tilt amount detection in an LED printer including a plurality of exposure heads (LED print heads).

[Explanation of symbols]

11 Image Memory (Video Memory) 12 Buffer Memory Circuit 13 Data Sorting Circuit 14 Memory Control Circuit 15 Exposure Head (LED Print Head) 16 LED Control Circuit 17 Exposure Head Position Detecting Device (Print Head Position Detecting Device) 21 Anode Driver 22 Cathode Driver 23 LED exposure device 24 LED element (mounting position display element)

Claims (6)

[Claims] 1. An exposure head having a plurality of light emitting arrays arranged in a main scanning direction, wherein the light emitting array is dynamically turned on and off according to image data to move at a predetermined scanning speed in a sub scanning direction. In an image forming apparatus that exposes an image bearing member to form an image, a position detection unit that detects a deviation of an exposure head from a predetermined mounting reference position and sends a deviation position detection signal, and the position detection signal. Based on the correction amount set according to the indicated shift, image data from (K-1) line (K is an integer of 2 or more) previous image data to the image data of the current line is selectively used as exposure data. An image forming apparatus comprising: a lighting control unit that dynamically controls lighting of the light emitting array according to exposure data. 2. The exposure head has first to mth m (m is 2)
An integer equal to or more than the light emitting array is provided, and a light emitting element is provided. When performing the dynamic lighting control in the order of the first to m-th light emitting arrays, the position detection unit determines the distribution of the amount of light received from the light emitting element. Accordingly, the deviation from the attachment reference position is detected, and the lighting control means is determined in accordance with the position detection signal, and the M-th (M is 1).
Based on the amount of deviation between the exposure line and the ideal exposure line by the light-emitting array (any integer from 1 to m).
2. The dynamic lighting control of the light-emitting array according to any one of the image data from the image data before the (K-1) line to the image data of the current line is performed. The image forming apparatus described. 3. The position detecting means includes a plurality of light receiving elements arranged in the sub-scanning direction, and one of the light receiving elements is used as a reference light receiving element to receive the light receiving amount distribution and a predetermined light receiving amount distribution. The image forming apparatus according to claim 2, wherein the deviation from the attachment reference position is detected according to the deviation from the mounting reference position. 4. The lighting control means selectively writes the first to Kth line buffer memories in which image data is written for one line and the first to Kth line buffer memories, respectively. While controlling the writing of the image data for one line to the write line buffer memory, one of the remaining line buffer memories is used as the read line buffer memory based on the position detection signal. The image forming apparatus according to claim 1, further comprising a memory control circuit that controls reading of the image data of lines. 5. The lighting control means further rearranges the image data read from the read line buffer memory so that the data arrangement is reversed between adjacent light emitting arrays, and the exposure is performed as rearranged image data. The image forming apparatus according to claim 4, further comprising: a data rearrangement circuit provided to the head, and a light emitting array control circuit that dynamically controls lighting of the exposure head according to the rearranged image data. 6. A plurality of exposure heads having a plurality of light emitting arrays arranged in the main scanning direction are provided, and the light emitting arrays are dynamically turned on and off for each of the exposure heads in accordance with image data, and a predetermined light emitting array is provided in the sub scanning direction. In an image forming apparatus that exposes an image carrier moving at a scanning speed to form an image, a deviation from a mounting reference position defined in advance for each exposure head is detected, and a position detection indicating the deviation for each exposure head is detected. Based on the position detection means for transmitting a signal and the correction amount set according to the shift indicated by the position detection signal, (K-1) lines (K is an integer of 2 or more) from the previous image data to the current line. The image data up to the image data is selectively used as exposure data, and lighting control means for dynamically controlling lighting of the light-emitting array is provided for each of the exposure heads according to the exposure data. And an image forming apparatus.