JP2007021896A - Image writing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image writing apparatus which can improve a one-dot printing ratio by enabling an increase/decrease in printing density for the width of a one-line section. <P>SOLUTION: This image writing apparatus comprises: a plurality of light-emitting element array units; and an image data transfer control means which divides image data, equivalent to one line, for each of the light-emitting element array units, so as to transfer them, and which performs main scanning by driving each light-emitting element of the light-emitting element array unit. In the image writing apparatus, the light-emitting element array units are displaced by a predetermined amount in a sub-scanning direction in such a manner that the axial direction of a photoreceptor is set as a main-scanning direction, and arranged in a staggered pattern in the state of overlapping one another by a predetermined amount in the main-scanning direction. The image data transfer control means drives a light-emitting element array by transferring the image data, equivalent to one line, to a main-scanning-direction one-line section in several batches, while processing the image data through the use of each of the light-emitting element array units. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image writing apparatus using a light emitting element array such as an LED array, and an image forming apparatus such as a printer, a digital copying machine, and a multifunction machine equipped with the image writing apparatus. The present invention relates to an image writing apparatus that can be increased or decreased and can significantly improve the 1-dot printing rate.

In general, image writing apparatuses for irradiating a photosensitive member with light to write a latent image include an LD scanning method using a laser beam and a method using a light emitting element array in which LED light emitting elements are arranged in an array.
In the above light emitting element array method, when a binary image is output from the image forming apparatus, one dot is printed in a horizontally thick elliptic system depending on the process conditions. Image), the vertical lines appear thicker than the horizontal lines, and the aspect ratio becomes a problem.
In order to solve this problem of aspect ratio, there is a method in which control is performed using balance correction data of LEDs, and as multi-value data, gradation data for each LED and a block composed of a plurality of LEDs The data for correcting the output variation and the data for correcting the output variation with respect to the average value of the blocks are added, and the LED variation is suppressed by the added data.
As a prior art, as Patent Document 1, a plurality of writing devices are arranged in a zigzag pattern along the axial direction of the photosensitive member, and the imaging positions are shifted in the rotational direction of the photosensitive member. An LED head (light emitting element array unit) is configured, and the image data to be transferred to each LED head is divided by the LED writing control circuit for each LED head based on an instruction from the printer control circuit. A technique for transferring image data to each LED head by shifting the image data in the rotational direction (feeding direction) of the photosensitive member in time, and effectively using the divided exposure data transfer method as Patent Document 2. The LED elements arranged in a line form a dot latent image on the photosensitive member while appropriately lighting a plurality of times in the sub-scanning direction for each scanning line, and the light between the LED elements. A technique for controlling the number of times of lighting in the sub-scanning direction based on a correction value corresponding to the variation in the above-mentioned difference is disclosed in Patent Document 3, in which the beam diameter in the sub-scanning direction is different from the original beam diameter (reference beam diameter). The light-emitting element is turned on multiple times by changing the position in the sub-scanning direction with a different intensity (light intensity) for a single lighting signal, and the combined profile matches the original beam diameter profile Thus, a technique for suppressing density unevenness caused by variations in the beam diameter in the sub-scanning direction for each light emitting element is disclosed.
JP 2002-283609 A JP-A-6-270471 JP 2001-121745 A

However, in the binary method, there is a control to faithfully reproduce the gradation by adding the binary image data and the correction data of each LED, but the dot printing power (printing drive current control) is adjusted. Therefore, although the line drawing was improved, the vertical and horizontal line widths were not improved.
The present invention has been made to solve the above-described conventional problems, and the object thereof is to increase or decrease the printing density with respect to the width between one line, and to significantly improve the one-dot printing rate. An image writing apparatus is provided.

In order to achieve the above-mentioned object, the invention according to claim 1 is a light-emitting element array in which light-emitting elements whose light emission is controlled according to binary image data are arranged in one direction, and light emission of the light-emitting element array. A plurality of light emitting element array units provided with image forming means for forming an image of light on the photosensitive member, and image data for one line are divided for each light emitting element array unit and transferred to each light emitting element array unit. An image writing apparatus comprising image data transfer control means for driving the respective light emitting elements of the light emitting element array unit to perform main scanning, wherein the image data transfer control means includes 1 between one line in the main scanning direction. The image data for lines is transferred in several times while data processing is performed by each light emitting element array unit, and the light emitting element array is driven.
According to a second aspect of the present invention, the image data transfer control means processes one line of image data by one of the light emitting element array units between one line in the main scanning direction. The light emitting element array is driven by transferring data twice.
The invention according to claim 3 is characterized in that the image data transfer control means performs pattern recognition by one line control of the main scanning in the data processing of the image data.

According to a fourth aspect of the present invention, when the image data transfer control means recognizes a 1 dot isolated point that is a binary image in the image data, the first transfer transfers one of the binary data, The second transfer is characterized in that transfer control of the other binary data is performed.
According to a fifth aspect of the present invention, when the image data transfer control unit recognizes a 1-dot isolated point that is a binary image in the image data, the first transfer transfers data “1” that is black. The second transfer is characterized in that transfer control is performed on data “0” which is white.
According to a sixth aspect of the present invention, the light emitting element array units are arranged in a staggered manner with a predetermined amount shifted in the sub-scanning direction with the axial direction of the photoconductor as the main scanning direction and a predetermined amount overlapping in the main scanning direction. It is characterized by being.
According to a seventh aspect of the present invention, the image data transfer control means switches the image data processing depending on the output mode in the data processing of the image data, and the data transfer is converted only once in the first mode. In the second mode, data processing is controlled by performing data transfer twice in the second mode.
Further, in the invention according to claim 8, the image data transfer control means switches the processing of the image data according to the output mode including the copier mode and the printer mode in the data processing of the image data, and the data transfer is performed in the copier mode. Conversion control is not performed only once, and data processing is controlled by performing data transfer twice in the printer mode.

  According to the present invention, the image data transfer control means performs transfer control several times (in this embodiment, two data transfers per line) while processing image data for one line during one main scanning line. By driving the light emitting element array, the print density can be increased or decreased with respect to the width between one line, and the one-dot printing rate can be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(Example)
FIG. 1 is a block diagram of an image forming apparatus (digital copying machine) to which an embodiment of an image writing apparatus according to the present invention is applied.
As shown in FIG. 1, the digital copying machine includes a document reading unit 100 as a reading unit that reads a document, an image information storage unit 300 as a storage unit that stores read document information, and transfers the stored information to a transfer sheet. The system includes a writing unit 500 for copying data, a system control device 302 for executing and controlling a series of processes, an operation unit 400 as an operation means for performing key input to the system control device, and the like.
Next, the configuration of the document reading unit 100 will be described with reference to FIGS. 2 and 1. FIG. 2 is a block diagram of the digital copying machine shown in FIG.
First, when the operator inserts a document from the insertion slot, the document is conveyed between the contact sensor 2 and the white roller 3 according to the rotation of the roller 1 (FIG. 2). The document being conveyed is irradiated by the LED attached to the contact sensor 2, and the reflected light is imaged on the contact sensor 2, and the document image information is read. The document image formed on the sensor 2 in FIG. 1 is converted into an electrical signal, and this analog signal is amplified by the image amplification circuit 102. The A / D conversion circuit 103 converts the analog image signal amplified by the image amplification circuit 102 into a multi-value digital image signal for each pixel. The converted digital image signal is output in synchronization with the clock output from the synchronization control circuit 106, and the shading correction circuit 104 corrects distortion due to light amount unevenness, contact glass contamination, sensor sensitivity unevenness, and the like. The corrected digital image information is converted into digital recording image information by the image processing circuit 105 and then written in the image memory unit 301.
Next, configurations of the system control device 302 and the writing unit (image writing device) 500 that control a series of processes for forming an image signal written in the image memory unit 301 on a transfer sheet will be described.
The system control circuit 302 has a function of performing overall control. The image data transfer in the reading control circuit 107, the synchronization control circuit 106, the image memory unit 301, and the LED writing control circuit 502 and the drive control circuit 504, the scanner driving device 108, A motor or the like is driven via the printer driving device 505 to smoothly control the reading document and transfer paper.
In the writing unit 500, the image signal transferred from the image memory unit 301 by the synchronization signal clock is converted into bits by one pixel by the LED writing control circuit 502, and converted into infrared light by the LPH 503.

Hereinafter, a process until an image is formed on a recording sheet will be described with reference to FIG.
Around the photosensitive drum 5, a charging device (scorotron charger with grid) 4 for uniformly charging the photosensitive drum 5 to -1200 V, and LEDs are arranged in an array, and an SLA (selfoc lens array) is arranged. A light emitting element array unit (LED head) 6 that irradiates the photosensitive drum 5 via the photosensitive drum 5 and a developing unit 7 are disposed. The LED head 6 corresponds to the LPH in FIG.
When the photoconductor drum 5 is irradiated with LED light based on digital image information, the charge on the surface of the photoconductor flows to the ground of the photoconductor drum 5 due to a photoconductive phenomenon and disappears. Here, the portion where the document density is low does not emit the LED, and the portion where the document density is high emits the LED. As a result, an electrostatic latent image corresponding to the density of the image is formed on the LED light non-irradiated portion of the photosensitive drum 5.
Next, the electrostatic latent image is developed by the developing unit 7. The toner in the developing unit is negatively charged by stirring and a bias of −700 V is applied, so that the toner adheres only to the LED light irradiated portion.
On the other hand, the transfer paper is selected from three paper feed stands and manual feed, and passes through the lower part of the photosensitive drum 5 at a predetermined timing by the registration roller 8, and at this time, the toner image is transferred onto the recording paper by the transfer charger 9. The recording paper is then separated from the photosensitive drum 5 by the separation charger 10 and is transported by the transport tank 11 and sent to the fixing unit 12 where the toner is fixed on the recording paper. The recording paper on which the toner is fixed is sent to the front and back of the apparatus by a paper discharge tray 14 or 13 and discharged.
Next, the flow of image signals from the image memory unit 301 to the writing unit 500 will be described.
Regarding the flow of the image signal, binary image data of even pixels (EVEN) and odd pixels (ODD) is simultaneously sent from the image memory unit 301 to the LED writing control circuit 502 at a transfer rate of 16 MHz. The image signal sent in parallel by two pixels is temporarily combined into one line in the LED writing control circuit 502, then assigned to three divisions, and four pixels are sent to the LED heads 6-1, 6-2 and 6-3. It is transferred at the same time.

Next, each block of the LED write control circuit 502 will be described with reference to FIG. FIG. 3 is a block diagram of each block of the LED write control circuit 502 shown in FIG.
First, the image data input unit 512 will be described.
The binary image signal, even pixel (EVEN), odd pixel (ODD), and timing signal are converted from parallel to serial from the image data memory unit 301 using the low voltage operation signal element LVDS driver, and the LED write control circuit 502 Is sent at 16MHz. The LED write control circuit 502 also uses the LVDS receiver 512 to convert from a serial signal to a parallel signal, and inputs it to the IC 510 as PKDE, PKDO, CLKA, LSYNC_N, LGATE_N, and FGATE_N.

Next, the image data RAM units 514A_1 to 514A_3 and 514B_1 to 514B_3 will be described.
The even-numbered pixel (EVEN) and odd-numbered pixel (ODD) image signals input to the IC 510 are set in units of four pixels, and are SRAMDI [3: 0] by the SRAM address signals ADRA [10: 0] and ADRB [10: 0]. , 3 group A SRAMs (514A_1 to 514A_3) and 3 group B SRAMs (514B_1 to 514B_3) are stored at a transfer rate of 8 MHz. Since 501_1 to 503_3 have a total number of dots 23040 dots (A3 width 7680 dots × 3) and image signal transfer is divided into three, the image signals for one main scanning line are transferred to the SRAM 514A_1 of the A group and the image signals of the LED head 6-1. The image signal of the LED head 6-2 is stored in the SRAM 514A_2, and the image signal of the LED head 6-3 is stored in the SRAM 514A_3. The image signals sequentially stored in the three A group SRAMs 514A_1 to 514A_3 at 8 MHz are simultaneously read out from the three A group SRAMs (514A_1 to 514A_3) at 4 MHz on the next second line, and are input to the IC 510 again. The image data is converted from 4 pixels to 8 pixels and sent to the field memories 515_1 to 515_3 of the image delay memory unit at a transfer rate of 2 MHz. At this time, the LED head 6-1 does not perform a delay operation. The image signal of the LED head 6-2 is transferred to the field memory 515-1, and the LED head 6-3 is transferred to the field memory 515-3. While the readout control from the SRAM of the first line is being performed, the image signal is stored in the three lines of the B group SRAMs 514B_1 to 514B_3 in the same manner as in the A group.
This read / write operation is performed by toggling the three A group SRAMs 514A_1 to 514A_3 and the three B group SRAMs 514B_1 to 514B_3, thereby connecting the lines.

Next, the image data delay units 515_1 to 515_3 will be described.
1) About the image signal delay units 515_1 and 515_2 of the LED head 6-2 The three A3 width LED heads 6-1 to 6-3 which are the light emitting element array units are arranged in a staggered manner. As a reference, the LED head 6-2 is mounted with a shift of 17.5 mm in the sub-scanning direction in the mechanical layout. That is, the LED heads (light emitting element array units) 6-1 to 6-3 are staggered in a state where they are shifted by a predetermined amount in the sub-scanning direction with the axial direction of the photosensitive drum 5 as the main scanning direction and overlapped by a predetermined amount in the main scanning direction. Are arranged in a shape.
For this reason, when the image signals output from the three A group SRAMs 514A_1 to 514A_3 and the three B group SRAMs 514B_1 to 514B_3 are simultaneously processed and transferred to the LED head 6-2, the LED head 6-2 is connected to the LED head 6-2. Is printed with a shift of 17.5 mm (17.5 mm / 42.3 μm (600 dpi 1 dot) = 416 lines) in the sub-scanning direction. In order to correct this mechanical shift, the image signal of the LED head 6-2 output from the A group SRAM 514A_2 and the B group SRAM 514B_2 at 4 MHz is set to 8 pixels, and is transferred to the field memory 515_1 in 180 MHz at 2 MHz in the order of transfer lines (fixed). Write.
Next, image signals are read from the field memory 515_1 at 2 MHz in the order of writing, and at the same time, 236 lines (variable) are written to the cascade-connected field memory 515_2.
Next, an image signal is read from the field memory 515_2 at 2 MHz in the order of writing, and is input to the IC 510 again as L2DFMO [7: 0]. As a result, the image signal of the LED head 6-2 is delayed by 416 lines. Since the number of lines to be delayed varies depending on the part system of the LED head 6-2 and the variation in assembly, it can be controlled in units of one line (42.3 um).

2) About the image data delay part of the LED head 6-3 Since the three A3 width LED heads 6-1 to 6-3 are arranged in a staggered manner, the LED head 6-3 is based on the LED head 6-1. In the mechanical layout, it is attached with a shift of 0.5 mm in the sub-scanning direction. Therefore, when the image signals output from the three A group SRAMs 514A_1 to 514A_3 and the three B group SRAMs 514B_1 to 514B_3 are simultaneously processed and transferred to the LED head 6-3, the LED head 6-3 is connected to the LED head 6-1. Prints with a shift of 0.5 mm (0.5 mm / 42.3 μm (1 dot at 600 dpi) = 12 lines) in the sub-scanning direction. In order to correct this mechanical shift, the image signals of the LED head 6-3 output from the A group SRAM 514A_3 and the B group SRAM 514B_3 at 4 MHz are written in units of 8 pixels into the field memory 515_3 in 12 lines at 2 MHz in the order of transfer lines.
Next, an image signal is read from the field memory 515_3 at 2 MHz in the order of writing, and is input again to the IC 510 as L3DFMO [7: 0]. As a result, the image signal of the LED head 6-3 is delayed by 12 lines.
Since the number of lines to be delayed varies depending on the part system of the LED head 6-3 and the variation in assembly, it can be controlled in units of one line (42.3um).
Next, the image data RAM units 550A_1 to 550B_1 to 550B_1 to 3 will be described.
The image data L1DI [7: 0] of the LED head 1 from the image data RAM unit 1 and the image data L2DFNO [7: 0] and L3DFMO [7: 0] of the LED heads 2 and 3 from the image data delay unit are IC510. Are stored in the SRAM groups 550A_1 to 550A_1 to 3 of the image data RAM unit 2 respectively at a transfer rate of 2 MHz. The stored image data is read out four times at the transfer rate of 8 MHz between the next lines. Since the address is the LED head 7680 dots and the unit is 8 pixels, it corresponds to 960 addresses. This 960 address is repeated four times. Image data read in units of 8 pixels is converted into units of 4 pixels in the IC 510 and transferred to the image data output unit 519.
While the SRAM groups 550A_1 to 550A_3 are being read, the SRAM groups 550B_1 to 550_3 write next line data, and alternately write and read lines.

Next, the image data output unit 519 will be described.
The 4-bit unit image data of the LED heads 6-1 to 3 processed by the image RAM unit 2 is output together with the LPH control signal and transferred to each LED head 6-1 to 3 at a speed of 8 MHz through the driver 519. (L1 to L3CLK are determined at the rising and falling edges of 4 MHZ).
Next, the light amount correction RAM 516 will be described.
The LED heads 6-1 to 3 have a light amount correction ROM in each LED head in order to store correction data for each LED element and correction data for each LED array chip in order to correct the light amount variation of each LED element. It is installed. When the power is turned on, the light amount correction data of the LED head 6-1 is first read out by CPLD control of the IC 510, serial / parallel converted, and stored in the light amount correction SRAM 516 by the address as 8-bit correction data HOSEID [7: 0]. After storing all the correction data, this time, it is read from the light quantity correction SRAM 516 and transferred to the LED head 6-1 again. This operation is sequentially performed with the LED heads 6-2 and 3.
The transferred light amount correction data is configured such that the correction data is held inside the LED heads 6-1 to 3 unless the LED heads 6-1 to 3 are turned off.
Next, the system driving device 302 will be described.
Write condition setting to the LED head write control circuit 502 is performed by the control signal input data bus LDATA [7: 0], the address bus LADR [5: 0] from the system controller 302, the latch signal VDBCS, and the P sensor pattern signal SGATE_N. Is input to the IC 510.
The following describes the overall control of the machine, the transfer control of image data to the LED head of the present embodiment configured by the LED write control circuit 502, the print dot diameter, and the image. The system driving device 302 and the LED writing control circuit 502 constitute image data transfer control means.
First, the basic transfer method to the LED head will be described.

4A and 4B are explanatory diagrams of a transfer method to the LED head, FIG. 4A is a timing diagram of data transfer to the LED head, and FIG. 4B is a description of data conversion processing in units of 8 pixels of image data. FIG.
As shown in FIG. 4A, RLSYNC is an interval of one main scanning line, and a series of processing is performed during this interval. Image data is transferred at the rising and falling edges of the clock. DATA is image data in units of 4 pixels.
As the transfer image data, first, (1) even pixel data: EVENDATA for 7680 pixels of the LED head is transferred. After the transfer, the data is latched by the LOAD signal. Next, (2) odd pixel data: ODDDATA is transferred and latched again by the LOAD signal. While the odd pixel data: ODDDATA is being transferred, the LED is turned on by the lighting signal: STRB of the latched even pixel data (STRB signal: LOW active). Again, (3) even data, (4) odd data transfer, latch, print, and data transfer are repeated twice for printing. That is, data transfer is performed twice between one line.
Next, an example of data conversion processing in units of 8 pixels of image data output from the image data RAM unit 2 (550A_1 to 550B_1 to 3) in FIG. 3 will be described with reference to FIG. In FIG. 4B, the address 0 is represented by ● ○○ ● ○ ●● ○ → 10010110 when the 8-pixel data is rearranged by setting the black circle to “1” and the white circle to “0”.
As an example, image data 8 pixels (10010110) read from address 0 of SRAM 550A_1 pay attention to even data in the first transfer, select only even data from 8 pixels, and transfer it to the LED head in 4-bit units. To do. This operation is repeatedly transferred to addresses 0 to 959. Accordingly, only the EVEN data is selected in the first transfer, and 1001 is transferred out of ● ○○ ● ○ ●● ○.

Next, the second data transfer is started, and the image data 8 pixels (10010110) read from the address 0 of the SRAM 550A_1 are now focused on the odd data, and only the odd data is selected from the 8 pixels, in units of 4 bits. To transfer to the LED head. This operation is repeatedly transferred to addresses 0 to 959. Therefore, in the second transfer, only ODD data is selected, and 0110 out of ● ○○ ● ○ ●● ○ is transferred.
In the first and second 8-bit to 4-bit conversion, the data value is set to 4 bits without processing the data value.
Next, the third data transfer is started, and even data is focused on 8 pixels of image data read from the address 0 of the SRAM 550A_1. If the data is “0”, “0” is transferred as it is. When the data is “1”, if the previous pixel (odd pixel) data is “1”, “1” is transferred as it is. However, if the previous pixel data is “0”, the data is transferred with “0”.
Since data processing is performed by pattern recognition at the third image transmission, 10010110 → 00000110. That is, in the third image transmission, only the EVEN data is transferred again, but here, it is recognized as a one-dot vertical line and data conversion is performed. In other words, looking at the left and right pixels, if it is 0 data, it is determined to be a vertical line. As a result, when the input data is data-converted, it becomes: ● ○○ ● ○ ●● ○ → ○○○○○ ●● ○. EVEN data is selected from this pattern, and 0001 is transferred accordingly.
From here, 0001 for four pixels of even data is selected and transferred to the LED head.
The same is true for the fourth time, and this time, odd-numbered data corresponding to four pixels 0010 is selected and transferred to the LED head. That is, since only the ODD data is transferred for the fourth time, 0010 is transferred according to OOXXX.

In the above-described embodiment, in the image data processing, the image data processing is switched according to the output mode consisting of the copier mode and the printer mode. In the copier mode, the data transfer is performed only once, and the conversion control is not performed. In the mode, data transfer is performed twice to control data processing.
By processing the data by performing such pattern recognition, there is the following effect of the vertical line width.
That is, the image data transfer control means controls the transfer several times (in this embodiment, two data transfers between one line) while processing the image data for one line during one main scanning line, and the light emitting element array is controlled. Since it is driven, the print density can be increased or decreased with respect to the width between lines, and the 1-dot printing rate can be improved.
Further, since the image data processing is such that pattern recognition is performed by main scanning one line control, the circuit configuration is easy and the line drawing between one line can be faithfully reproduced.
In addition, when a 1-dot isolated point that is a binary image is recognized, the first transfer transfers black, that is, “1”, and the second transfer controls white, that is, “0”, so that the dot diameter is reduced. It is possible to improve the vertical / horizontal ratio of one dot.
In addition, the output mode, that is, the copier mode and the printer mode can be separated, so that the gradation in the image processing in the copier mode and the gradation and line drawing in the data processing in the printer mode can be faithfully reproduced. became.

FIG. 5 is an explanatory diagram of the relationship between the printed dot diameter of a 1-dot cross of 7 dots per line in the main scanning direction and 7 lines in the sub-scanning direction, and the apparent image. (A) Prints data transfer once It shows the case. (B) shows the case where the data transfer is printed twice, and (c) shows the two data transfers of data “1” and data “0” in the case of 1 dot isolated point. ing.
As shown in FIG. 5A, when the data transfer of data “1” is printed at a time as in the conventional case, the vertical line width shown in (6) is considerably thicker than the horizontal line width of (7). The ratio will increase.
As shown in FIG. 5B, when data “1” is transferred twice and data “1” is printed twice (that is, when data “1” is transferred twice), (9 ) Is slightly thicker, and the aspect ratio with the vertical line shown in (8) is improved. However, the ratio between the vertical line width shown in (8) and the horizontal line width shown in (9) is thicker at 1 dot line width. It was different.
Next, in this embodiment, as shown in FIG. 5C, the data transfer is performed twice. However, in the case of 1 dot isolated point, that is, in the 1 dot vertical line, the data “1” is transferred for the first time and 2 In the second time, transfer control is performed to transfer data “0”.
Therefore, as shown by (5) (1 dot isolated point) in FIG. 5C, data “1” is printed for the first time, and data “0” is not printed for the second time. As a result, the vertical line in (10) becomes thinner and the horizontal line in (11) becomes slightly thicker, and the ratio between the vertical line width shown in (10) and the horizontal line width in (11) becomes equal.
As shown in FIG. 5C, since (1) to (4) are horizontal lines and not 1-dot isolated points, data transfer of data “1” is printed twice.
In this way, the vertical line can be thinned by pattern recognition of the 1 dot isolated point in the order of even pixel data → odd pixel data → even pixel data → odd pixel data in the order of image data twice per line. , Improve the aspect ratio.

Here, the reason why the dot diameter of the vertical line can be reduced will be described in detail below.
If the data “1” is transferred for the first time, the data “0” is transferred for the second time, and the printing time is assumed to be 100, normally, it is 100 for one transfer of the data “1”. However, in this embodiment, the number of transfers is 100.
Therefore, since the data is “1” for the first time and the data is “0” for the second time, the printing time is halved. In the fourth line, there is a horizontal line with one dot and there is a dot next to it, so it is not an isolated point. “1” is transferred and the printing time becomes 100 ((1) to (4) in FIG. 5C).
In this way, in the case of a 1-dot vertical line, the amount of data is reduced and the line is made thinner by reducing the printing time.

1 is a block diagram of an image forming apparatus (digital copying machine) to which an embodiment of an image writing apparatus according to the present invention is applied. It is a block diagram of the digital copying machine shown in FIG. FIG. 2 is a configuration diagram of each block of an LED write control circuit 502 shown in FIG. 1. It is explanatory drawing about the transfer system to an LED head, (a) is a timing diagram about the data transfer to an LED head, (b) is explanatory drawing of the data conversion process of 8 units of image data. It is explanatory drawing of the relationship between the printing dot diameter of a 1 dot cross and an appearance image, (a) is a figure which shows the case where data transfer is printed once, (b) is printed by performing data transfer twice. (C) is a diagram showing a case where the data transfer according to the present invention is performed twice and a 1-dot isolated point is associated with the second data.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Roller, 2 ... Contact | adherence sensor, 3 ... SRAM, 5 ... Photosensitive drum, 6 ... LED head, 7 ... Development unit, 8 ... Registration roller, 9 ... Transfer charger, 10 ... Separation charger, 11 ... Conveyance tank, 12 DESCRIPTION OF SYMBOLS ... Fixing unit 14, 13 ... Paper discharge tray, 100 ... Document reading unit, 102 ... Image amplification circuit, 103 ... Conversion circuit, 104 ... Shading correction circuit, 105 ... Image processing circuit, 106 ... Synchronization control circuit, 107 ... Reading Control circuit 108... Scanner drive device 300... Image information storage unit 301... Image memory unit 302... System control device 400 ... operation unit 500. Control circuit, 505... Printer driving device, 510... IC, 512... LVDS receiver, 514 A. SRAM, 514 B. SRAM, 51 ... field memory, 516 ... SRAM, 519 ... image data output unit, 550A ... SRAM, 550B ... SRAM

Claims (8)

A plurality of light-emitting elements including a light-emitting element array in which light-emitting elements whose light emission is controlled in accordance with binary image data are arranged in one direction, and an imaging unit that forms an image of light emitted from the light-emitting element array on a photosensitive member Image data for main scanning by dividing the element array unit and image data for one line into each light emitting element array unit and transferring them to each light emitting element array unit and driving each light emitting element of the light emitting element array unit An image writing apparatus comprising transfer control means,
The image data transfer control means transfers the image data for one line between the lines in the main scanning direction in several times while performing data processing on each light emitting element array unit, and the light emitting elements An image writing apparatus for driving an array.   The image data transfer control means performs data transfer twice between one line while processing the image data for one line in each light emitting element array unit between one line in the main scanning direction, The image writing apparatus according to claim 1, wherein the light emitting element array is driven.   2. The image writing apparatus according to claim 1, wherein the image data transfer control means performs pattern recognition by one line control of the main scanning in data processing of the image data.   When the image data transfer control unit recognizes a 1 dot isolated point that is a binary image in the image data, the first transfer transfers one binary data, and the second transfer transfers the other binary data. The image writing apparatus according to claim 2, wherein data transfer is controlled.   When the image data transfer control unit recognizes a 1-dot isolated point that is a binary image in the image data, the first transfer transfers black data “1”, and the second transfer data becomes white. The image writing apparatus according to claim 2, wherein transfer control of “0” is performed.   The light-emitting element array units are arranged in a staggered manner with a predetermined amount shifted in the sub-scanning direction with the axial direction of the photoconductor as the main scanning direction and overlapping by a predetermined amount in the main scanning direction. 2. The image writing apparatus according to 1.   In the data processing of the image data, the image data transfer control means switches the processing of the image data depending on the output mode. In the first mode, the data transfer is not controlled once, and in the second mode, the data is not controlled. 7. The image writing apparatus according to claim 1, wherein the data processing is controlled by performing transfer twice.   The image data transfer control means switches image data processing according to an output mode consisting of a copier mode and a printer mode in the data processing of the image data. In the copier mode, the data transfer is not converted and controlled only once. 8. The image writing apparatus according to claim 7, wherein in the mode, data processing is controlled by performing data transfer twice.

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