JP2008036850A - Image forming apparatus and image forming method - Google Patents

Abstract

Provided are an image forming apparatus and an image forming method for preventing image quality deterioration when a light emitter array is mounted at an angle and performing smooth image formation.
In a light emitter array, a light emitting element array in which a plurality of light emitting elements are arranged in a main scanning direction is made to correspond to a single lens having a negative optical magnification, and a set of the lens and the light emitting element array is arranged in the main scanning direction. Are provided in the sub-scanning direction. The inclination of the light emitter array 1 is detected, and the skew correction control module 21 creates skew correction image data. This skew-corrected image data is written into the MLA line buffer memory 38, and the read address is determined by the MLA control memory read address 34 with reference to the main scanning direction inversion LUT 35, the intra-group timing LUT 36, and the inter-group timing LUT 37, and the image data is Transmit to the light emitter array 1.
[Selection] Figure 1

Description

  The present invention provides an image forming apparatus and an image forming method for preventing deterioration of image quality when a light emitter array is attached to a main body in a tilted manner when a lens having a negative optical magnification is used, and performing smooth image formation It is about.

  In general, an electrophotographic toner image forming unit includes a photosensitive member as an image bearing member having a photosensitive layer on an outer peripheral surface, a charging unit that uniformly charges the outer peripheral surface of the photosensitive member, and a uniform charging unit using the charging unit. An exposure unit that selectively exposes the outer peripheral surface charged to form an electrostatic latent image, and a toner as a developer is applied to the electrostatic latent image formed by the exposure unit to form a visible image ( Developing means for forming a toner image).

  As a tandem type image forming apparatus for forming a color image, a plurality (for example, four) of toner image forming means as described above are arranged on the intermediate transfer belt. The toner image on the photosensitive member by the single color toner image forming unit is sequentially transferred to the intermediate transfer belt, and the toner images of a plurality of colors (for example, yellow, cyan, magenta, and black (black)) are superimposed on the intermediate transfer belt. There is an intermediate transfer belt type that obtains a color image on an intermediate transfer belt.

  In a tandem color image forming apparatus (printer), a technique using a light emitter array as the exposure means (line head) is known. For example, Patent Document 1 describes an example in which a latent image is formed by magnifying output light of a light emitting element arranged two-dimensionally in a light emitter array with a single lens and irradiating the photosensitive drum. .

JP 2001-63139 A

  When a light emitter array as described in Patent Document 1 is used as a line head, the light emitter array may be attached to the main body while being mechanically inclined. As described above, when the light emitter array is mechanically inclined and attached to the main body, the image forming position on the image carrier is not accurately irradiated with the output light of the light emitting element, and the image quality is deteriorated. Patent Document 1 has a problem in that no means for preventing such image quality deterioration is described.

  Further, in the light emitter array described in Patent Document 1, the single lens 14 reverses the output light of the light emitting member 1 in the main scanning direction as shown in FIG. The drum 15 is irradiated. That is, the single lens 14 has a negative optical magnification. Therefore, unlike SLA (Selfoc lens array), the optical magnification is positive and the output light of the light emitting element is different from the case where the image carrier is irradiated in the optical axis direction. When a light emitter array as described in Patent Document 1 is used as a line head, in order to perform image formation smoothly, how to read out image data stored in a memory and perform predetermined printing. Alternatively, a specific memory configuration and image data reading sequence are required. However, Patent Document 1 has a problem that it does not describe this.

  The present invention has been made in view of the above-described problems of the prior art, and its purpose is that when a lens having a negative optical magnification is used, the light emitter array is attached to the main body at an angle. An object of the present invention is to provide an image forming apparatus and an image forming method capable of preventing image quality deterioration and performing smooth image formation.

An image forming apparatus of the present invention that achieves the above object is an image forming apparatus that simultaneously forms images of a plurality of colors on an image carrier using a plurality of line heads corresponding to the respective colors,
A plurality of light emitting element rows arranged in the main scanning direction are arranged in the sub scanning direction to form a light emitter block, and a plurality of the light emitting blocks are arranged in the main scanning direction and the sub scanning direction, and each light emission A light emitter array (line head) in which a single lens having a negative optical magnification is associated with a body block;
Means for detecting an inclination with respect to a normal attachment position when the light emitter array is attached to the main body, means for creating skew correction image data according to the detected inclination of the light emitter array, and supplying to each light emitting element Storage means for storing image data to be performed, and control means for reading the image data from the storage means and transmitting the image data to the light emitting elements,
The position of the imaging spot formed on the image carrier by each light emitting element in the skew corrected image data is reversed in the main scanning direction by each light emitter block, and the control means stores the skew in the storage means. Stores corrected image data, controls reading of the skew-corrected image data stored in the storage means so as to be inverted in the sub-scanning direction within each of the light emitter blocks, and arranges a plurality of arrays in the sub-scanning direction The readout is controlled so that the imaged spots formed by the respective light emitter blocks are arranged in a line in the main scanning direction of the image carrier. According to such a configuration, it is possible to prevent image quality degradation caused by the inclination of the light emitter array body attachment. In addition, when a single lens having a negative optical magnification is used, and when a plurality of issue element rows are arranged in the sub-scanning direction, image formation can be performed smoothly.

  The image forming apparatus according to the present invention is characterized in that the lenses are arranged in a plurality of rows in the sub-scanning direction with the leading position in the main scanning direction being shifted, and the light emitter block is associated with each lens. According to such a configuration, in an image forming apparatus in which lenses, for example, microlens arrays are arranged in a staggered manner, image quality deterioration can be prevented and image formation can be performed smoothly.

  The image forming apparatus of the present invention further includes a memory table for storing the skew-corrected image data, and the memory table stores image data for each light emitting element arranged in the main scanning direction of the light emitter array. A plurality of horizontal columns and a plurality of vertical columns for storing image data for each light emitting element are formed in a matrix so as to form a plurality of lines of imaging spots in the sub-scanning direction of the image carrier. When the direction of the inclination and the magnitude of the inclination are detected by the means for detecting the inclination of the light emitter array, the control means controls the write address of the skew correction image data to the memory table. Features. According to such a configuration, it is possible to smoothly store the skew-corrected image data when a lens having a negative optical magnification is used.

  In the image forming apparatus according to the aspect of the invention, the storage unit includes a second memory table having the same shape as the memory table storing the skew-corrected image data, and the control unit stores the second memory table in the second memory table. The skew-corrected image data is sequentially stored, and the reading of the skew-corrected image data from the second memory table is controlled so as to be reversed in the sub-scanning direction within each light emitter block. . According to such a configuration, it is possible to rationally form an image on the image carrier when a lens having a negative optical magnification is used.

The control means is configured for the light emitter blocks arranged in the sub-scanning direction based on the distance in the sub-scanning direction of the light emitting elements in the light emitter blocks and the moving speed of the image carrier. The timing of reading the skew-corrected image data from the second memory table is controlled. According to such a configuration, image formation can be smoothly performed using existing parameters.

  In the image forming apparatus of the present invention, the light emitting element is an organic EL element. Since the organic EL element does not need to reduce the diameter of the light emitting part, the light power of the light emitting part can be increased. For this reason, it is possible to use an organic EL material having a low luminous efficiency.

  Further, the image forming apparatus of the present invention includes at least an image forming station in which image forming units each including a charging unit, the line head described in any of the above, a developing unit, and a transfer unit are arranged around a carrier. Two or more are provided, and an image is formed by a tandem method by passing a transfer medium through each station. According to such a configuration, in the tandem color image forming apparatus, image quality deterioration caused by the inclination of the body of the light emitter array is prevented, and an image when a lens with a negative optical magnification is used is used. It is possible to rationally form an image on the carrier.

  In addition, the image forming apparatus of the present invention includes an intermediate transfer medium. According to this configuration, in an image forming apparatus having an intermediate transfer medium, it is possible to rationally prevent image quality deterioration and form an image on an image carrier when a lens having a negative optical magnification is used.

The image forming method of the present invention is an image forming method in which a plurality of color heads are simultaneously formed using a plurality of line heads corresponding to respective colors. A plurality of rows of light emitter blocks are formed in the scanning direction, a plurality of the light emitter blocks are arranged in the main scanning direction and the sub-scanning direction, and a single lens having a negative optical magnification is associated with each light emitter block. A light emitter array (line head) is provided,
A step of detecting an inclination with respect to a normal attachment position when the light emitter array is attached to a main body, a step of generating skew correction image data according to the detected inclination of the light emitter array, and a supply to each light emitting element Storing the skew-corrected image data as image data to be stored in a storage means so that the position of the imaging spot formed on the image carrier is inverted in the main scanning direction by each of the light emitter blocks; Controlling the reading of the skew-corrected image data stored in the means so as to be inverted in the sub-scanning direction within each light-emitting body block, and forming an image by each of the light-emitting body blocks arranged in the sub-scanning direction And controlling the reading so that the spots are arranged in a line in the main scanning direction of the image carrier. According to this configuration, it is possible to prevent image quality deterioration due to the inclination of the attachment of the light emitter array to the main body quickly and accurately without correcting the attachment position of the light emitter array. In addition, when a single lens having a negative optical magnification is used, image formation can be performed quickly and accurately by using the memory table having the above configuration.

  FIG. 16 is a schematic explanatory view showing an example of a light emitter array used as a line head in the embodiment of the present invention. In FIG. 16, the light emitter array 1 is provided with a plurality of light emitting element rows 3 in which a plurality of light emitting elements 2 are arranged in the main scanning direction in the sub scanning direction to form a light emitter block 4. In the example of FIG. 16, the light emitter block 4 forms two light emitting element rows 3 in which four light emitting elements 2 are arranged in the main scanning direction in the sub scanning direction. A large number of the light emitter blocks 4 are arranged in the light emitter array 1, and each light emitter block 4 arranged in the main scanning direction and the sub-scanning direction is arranged corresponding to the microlens 5. As the light emitting element 2, for example, an organic EL element is used. Since the organic EL element does not need to reduce the diameter of the light emitting part, the light power of the light emitting part can be increased. For this reason, it is possible to use an organic EL material having a low luminous efficiency.

  A plurality of microlenses 5 are provided in the main scanning direction and the sub-scanning direction of the light emitter array 1 to form a microlens array (MLA) 6. The MLA 6 is arranged with the leading position in the main scanning direction shifted in the sub-scanning direction. Such an arrangement of MLA can correspond to the case where the light emitting elements 1 are provided in a staggered manner in the light emitter array 1. In the example of FIG. 16, three rows of MLA 6 are arranged in the sub-scanning direction. And group C.

  FIG. 17 is an explanatory diagram showing an imaging position when the exposure surface of the image carrier is irradiated through the microlens 5 with the output light of each light emitting element 2 in the configuration of FIG. In FIG. 17, as described with reference to FIG. 16, the light emitter array 4 is arranged with the light emitter blocks 4 divided into the group A, the group B, and the group C. The light emitting element row of each light emitter block 4 of group A, group B, and group C is divided into 1 line and 2 lines, even numbered light emitting elements are assigned to 1 line, and odd numbered light emitting elements are assigned to 2 lines.

  The microlens 5 has a negative optical magnification, and when the output light of the light emitting element is irradiated, the imaging position 7 on the image carrier is a position reversed from the position of the light emitting element in the main scanning direction. In the example of FIG. 17, for the group A, the light emitting elements 1, 3, 5, 7 of 2 lines (odd number) are operated first. At this time, in the image carrier, imaging spots are generated at imaging positions 1, 3, 5, and 7 that are reversed from the position of the light emitting element in the main scanning direction. After moving the image carrier in the sub-scanning direction for a predetermined time, each light emitting element 2, 4, 6, 8 of one line (even number) is operated. Also in this case, in the image carrier, an imaging spot is generated at imaging positions 2, 4, 6, and 8 that are reversed from the position of the light emitting element in the main scanning direction.

  Since the optical magnification of the microlens 5 is negative, when the output light of the light emitting element is irradiated, the imaging position 7 on the image carrier is a position reversed from the position of the light emitting element in the sub-scanning direction. Therefore, the position of the imaging spot by each light emitting element 2, 4, 6, 8 on one line (even number) is the position of the imaging spot by each light emitting element 1, 3, 5, 7 on 2 line (odd number). In order to form in the same column in the main scanning direction, the image carrier as described above is moved in the sub-scanning direction, and then each light emitting element 2, 4, 6, 8 of one line (even number) emits light. It is necessary to let

  In this way, imaging spots are formed on the image carrier in the order of 1 to 8 in the same row in the main scanning direction. Thereafter, the image carrier is moved in the sub-scanning direction for a predetermined time, and the processing of group B is executed in the same manner. Further, by moving the image carrier in the sub-scanning direction for a predetermined time and executing the process of group C, the result is based on the input image data in the order of 1 to 28... In the same column in the main scanning direction. An image spot is formed on the image carrier.

  As shown in FIG. 16, in the light emitter array 1 in which the light emitting element array 3 and the MLA 6 are associated with each other, in order to form an imaging spot in one line in the main scanning direction on the image carrier as shown in FIG. The following image data processing is required. (1) Inversion correction of the light emitting element position and the imaging position in the sub-scanning direction in the light emitter block and control of the light emission timing by a single lens having a negative optical magnification, and (2) the optical magnification is negative. Inversion correction of the light emitting element position and the imaging position in the main scanning direction by a single lens, and (3) a plurality of grouped light emitting elements are arranged in the sub-scanning direction in a plurality of lens units having a negative optical magnification. So, control of the light emission timing between these groups. In the embodiment of the present invention, in order to solve the problems (1) to (3), the image data is stored in a line buffer memory formed by a memory table as described later, and the image data is read out. The address is controlled.

  By the way, when the line head using the light emitter array having a certain length in the main scanning direction is attached to the main body, the line head may be attached to be inclined with respect to the reference position. FIG. 3 is a perspective view showing an example in which the line head 101 using the light emitter array 1 shown in FIG. 16 is mechanically inclined and attached to a support member of the main body, for example, a frame (case). In this case, with respect to the image carrier (photosensitive drum) 41 rotating in the direction of arrow R, the line head 101 is shifted from the normal mounting position indicated by the broken line by arrows La and Lb at both ends. It is attached at a position 101a indicated by a solid line. The illuminant array 1 is also moved from the normal position and is indicated by the illuminant array 1a.

  FIG. 4 is an explanatory diagram showing only the line head, and the direction of positional deviation is different from FIG. That is, position shift (tilt) occurs in the counterclockwise directions Lp and Lr at both ends of the line head 101. FIG. 5 is an explanatory diagram showing the positions of the light emitting elements when the line head, and thus the light emitter array 1 is attached to the main body as shown in FIG. In FIG. 5, the light emitting element is located at a position indicated by a solid line with respect to a regular light emitting element position indicated by a broken line. In this example, as described above, the light emitter array 1 is tilted Lp and Lr counterclockwise at both ends, and the light emitting element is tilted counterclockwise by one pixel. That is, there is a skew. If image formation is performed in this state, a difference in density occurs in the print density, or image quality deterioration such as generation of streaks occurs. For this reason, some measures for preventing image deterioration are required.

  Conventionally, when the line head is attached to the main body at an inclination, various measures are taken as skew correction. However, in the embodiment of the present invention, since MLA is used in the optical system, as described above, it is necessary to control the timing of reading image data in the main scanning direction and the sub-scanning direction. For this reason, if image data control corresponding to MLA is executed after performing normal skew correction, there is a problem that the control algorithm becomes very complicated. Therefore, in the embodiment of the present invention, the image data written after the skew correction is stored in the memory table, and the read timing of the image data is controlled to perform MLA-compliant image formation.

  FIG. 2 is a flowchart showing a skew correction processing procedure. In FIG. 2, the process is started (S1), and the tilt amount and direction of the light emitter array are calculated (S2). Next, a write address to the memory is determined based on the calculated tilt amount and direction of the light emitter array (S3). Subsequently, the image data of the first line is written into the memory according to the write address (S4). Next, the image data of the second line is written into the memory according to the write address (S5). Image data stored in the bank 1 in the memory is read (S6). Thereafter, the same processing is repeated to write and read image data for one page (S7), and the processing is terminated (S8). An example of a memory table into which skew correction image data is written will be described with reference to FIGS.

  When the light emitter array is not normally attached to the main body and image quality deterioration occurs, it is necessary to perform alignment and fix the light emitter array at a normal position. However, there is a problem that the processing becomes complicated because time and labor are required to accurately adjust the position of the light emitter array. As described above, in the embodiment of the present invention, the electrical control can prevent the image quality deterioration caused by the inclination in the attachment of the light emitter array to the main body, so that complicated processing is required. There are advantages to not.

  6 to 10 are explanatory diagrams illustrating examples of the memory table 10 according to the embodiment of the present invention. 6 to 10, as described with reference to FIG. 5, the light emitter array includes the light emitting elements from the 1st to 24th pixels, the skew direction is counterclockwise, and one pixel is in the sub-scanning direction. It shows the state of writing and reading image data when it is tilted. In the example of FIG. 5, the light emitting elements 1 to 24 are centered on the light emitting elements 12 and 13 at the center, and the light emitting elements 1 to 12 are one pixel downstream in the sub-scanning direction with respect to the normal position. Is arranged. In addition, the light emitting elements 13 to 24 are arranged on the upstream side by one pixel in the sub-scanning direction with respect to the normal position.

  Therefore, the image data of the pixel position corresponding to each light emitting element is stored in the bank 1 of the memory table 10 in FIG. 6A and FIG. 6B, and the image data 1-13 to 1-24 corresponding to the pixels 13 to 24. Write. Further, image data 1-1 to 1-12 corresponding to the pixels 1 to 12 are written into the bank 2. Here, the bank 2 corresponds to an area in which image data is written at a position shifted from the bank 1 by one pixel in the sub-scanning direction. As described above, the image data for one line in the main scanning direction is formed by being divided into the memory table 10 according to the inclination direction of the light emitter array and the inclination amount converted by the pixel size. It is distributed and written to the banks that are.

  FIGS. 7A and 7B show processing at the timing next to FIGS. 6A and 6B. Here, the image data of the second line in the main scanning direction is stored in the memory table, and at the same time, the processing of reading out the image data stored in the bank 1 by the processing of FIGS. 6A and 6B is performed. That is, the image data 2-1 to 2-12 corresponding to the pixels 1 to 12 are written in the bank 3. In addition, image data 2-13 to 2-24 corresponding to the pixels 13 to 24 are written in the bank 2. At the same time, the image data 1-13 to 1-24 corresponding to the pixels 13 to 24 stored in the bank 1 are read and written to a second memory table provided separately for performing MLA-compliant control described later. .

  FIGS. 8A and 8B show processing at the timing next to FIGS. 7A and 7B. Image data 3-1 to 3-12 corresponding to the pixels 1 to 12 are written in the bank 4. In addition, image data 3-13 to 3-24 corresponding to the pixels 13 to 24 are written in the bank 3. At the same time, the image data 1-1 to 1-12 corresponding to the pixels 1 to 12 and the image data 2-13 to 2-24 corresponding to the pixels 13 to 24 stored in the bank 2 are read out, and Write to memory table for control.

  FIGS. 9 and 10 show image data stored in a memory table for performing control corresponding to MLA when the process described in FIGS. 6 to 8 is performed for one page. As shown in FIGS. 9 and 10, in this example, image data corresponding to each line in the main scanning direction is divided and stored in different banks in the pixels 1 to 12 and the pixels 13 to 24. . That is, the image data is divided into two and written in different banks with reference to the pixels 12 and 13 in the center.

  In the embodiment of the present invention, image data read-out control for an MLA-compatible light emitting element is performed using a memory table storing image data for skew correction as described with reference to FIGS. The general control for forming one row of imaging spots in the main scanning direction of the image carrier has been described with reference to FIG. 17, but the groups A, B, and C arranged at different positions in the sub-scanning direction are described. The control for forming one row of imaging spots in the main scanning direction of the image carrier by using the light emitting elements will be specifically described.

  FIG. 18 is an explanatory diagram showing an example of a memory table when one row of imaging spots is formed in the main scanning direction of the image carrier by the light emitting elements of groups A, B, and C. In FIG. 18, a plurality of horizontal columns of the memory table 10 assign pixel numbers 1 to 4 to group A, pixel numbers 5 to 8 to group B, and pixel numbers 9 to 12 to image data of group C light emitting elements. In the plurality of vertical columns, line 2 to line 4 are assigned to group C, line 12 to line 14 are assigned to group B, and line 22 to line 24 are assigned to image data of light emitting elements of group A.

  For example, when the time of the image data reading timings T1 and T2 is equivalent to 10 lines in the memory table of the line buffer, the image forming procedure is as follows. The image data Aa corresponding to the group A on the 22nd line of the memory table 10 is read, and the image data Ba corresponding to the group B on the 12th line is read after T1 time. Further, after (T1 + T2) time, the image data Ca corresponding to the group C of the second line is read and transmitted to the line head.

Here, the reading timings T1 and T2 are determined based on the distance d in the sub-scanning direction of the light emitting elements in the light emitter block and the moving speed s of the image carrier. For example, T1 can be obtained as follows.
T1 = | (d × β) / S |
Here, each parameter is as follows.
d: Distance in the sub-scanning direction of the light emitting element
S: Moving speed of image plane (image carrier) β: Lens magnification

  Next, the image data Ab, Bb, and Cb for the next line of the address read last time are read and transmitted to the line head. Next, the next image data Ac, Bc, Cc is read out by one line and transmitted to the line head. By repeating such a process 20 times, 2 to 22 lines of imaging spots are formed in a line on the image carrier (photoconductor). The above image forming process is performed for one page.

  Here, the image data Aa corresponds to pixel numbers 1 to 4, the image data Ba corresponds to pixel numbers 5 to 8, and the image data Ca corresponds to pixel numbers 9 to 12, respectively. The image data Ab and Ac correspond to pixel numbers 1 to 4, the image data Bb and Bc correspond to pixel numbers 5 to 8, and the image data Cb and Cc correspond to pixel numbers 9 to 12, respectively. That is, as shown in FIG. 16, when the light emitting element rows of groups A to C are arranged in the light emitter array 1, image data for the light emitting elements of group A are stored in the pixel numbers 1 to 4 in the memory table 10. Store in multiple lines.

  Similarly, image data for group B light-emitting elements are stored in a plurality of lines of the memory table 10 for pixel numbers 5 to 8, and image data for group C light-emitting elements are stored in the memory table 10 for pixel numbers 9 to 12. Stored in line. As described above, the memory table 10 of FIG. 18 stores image data by dividing one line of memory addresses into groups A to C.

  FIG. 1 is a block diagram illustrating an example of an embodiment of the present invention. In FIG. 1, the control device 20 includes a skew correction control module 21 and an MLA control module 31. Image data is transmitted from the controller 30 and stored in the skew correction memory 22. From the detection value by the inclination detecting means 23, the inclination calculating circuit 24 calculates the amount of inclination of the light emitter array 1 and the direction of the inclination. The skew memory write address control circuit 26 controls an address for writing the skew correction data to the skew memory (the memory table 10 shown in FIGS. 9 and 10) based on Hreq (horizontal direction request signal). The skew memory read address control circuit 26 controls an address for reading the skew correction data from the skew memory based on Hreq.

  The base pointer generator 32 of the MLA control module 31 generates a base point (base stage) based on the Hreq and Vreq (vertical) direction request signals, and the base data is transferred to the MLA control memory write address generator 33 and the MLA control memory. Transmit to read address generator 34. The base point (base stage) will be described with reference to FIGS. The MLA control memory write address generator 33 generates a write address and sends it to the MLA control line buffer memory 38 (second memory table shown in FIGS. 12 to 15). Further, the skew-corrected image data is transmitted from the skew correction memory 22 to the MLA control line buffer memory 38.

  The MLA control memory read address generator 34 receives the base data of the base pointer generator, determines the read address with reference to the inversion LUT 35, the intra-group timing LUT 36, and the inter-group timing LUT 37, and the MLA control line buffer memory 38. Send to. The MLA control line buffer memory 38 transmits the image data to the light emitter array 1.

  FIG. 11 is a flowchart showing a processing procedure when forming an image corresponding to MLA. In FIG. 11, processing is started (S11), and image data for skew correction is written in the base stage of the line buffer (S12). Here, the “base stage” is any one of the banks 1 to 49... In the memory table of FIGS. 12 and 13, and the bank 47 is displayed as the base stage in FIGS. Therefore, skew correction image data is written in the bank 47. Next, the base pointer counter is incremented. The base stage shifts to the bank 48 (S13).

  Image data for skew correction is written in the base stage 48 (S14). Based on the base position, the read address in the main scanning direction is determined with reference to the inversion LUT (S15). Subsequently, the read address in the sub-scanning direction is determined by referring to the timing LUT based on the base position (S16). Here, the readout address in the sub-scanning direction is determined for both the intra-group timing LUT 36 and the inter-group LUT 37 shown in FIG. Image data is read according to the determined address (S17). It is determined whether or not Read / Write for one page has been completed (S18). If the determination result is YES, the line buffer memory is cleared (S19), and the process is terminated (S20). If a determination result is No, it will return to the process of S13 and will repeat the loop process of S13-S18.

  Reading of image data from the MLA-controlled line buffer memory (memory table) will be described with reference to FIGS. 12 and 13 show pixels 1 to 24 and banks 1 to 47, and image data for skew correction is written in the banks 1 to 46 while being inverted in the main scanning direction. The bank 47 is set as a base stage, and image data for skew correction is newly written. Pixels 1 to 8 correspond to group A, pixels 9 to 16 correspond to group B, and pixels 17 to 24 correspond to group C in FIG.

  As described with reference to FIG. 17, each of the groups A to C includes a plurality of light emitting element rows formed by a single microlens with light emitting elements in the first row (even number) and the second row (odd number). The light emitter block 4 is made to correspond. The memory tables of FIGS. 12 and 13 have both the effects of reversing the image data in the sub-scanning direction of the light emitting element rows in each of the groups A to C and reversing the image data between the groups A to C. To do. In this example, the group A corresponds to the pixels 1 to 8, but the even-numbered image data (44-2 to 44-8) of the bank 45 and the odd-numbered image data (45-1 to 45-8) of the bank 46. 45-7) is read out.

  As described with reference to FIG. 17, image data for skew correction that has been inverted in the main scanning direction in advance is written in the memory tables of FIGS. 12 and 13. Therefore, when the odd-numbered image data (45-1 to 45-7) of the bank 46 is first read and transmitted to the light emitter array 1, the image carrier has 45-7 at the head position in the main scanning direction. An imaging spot based on the image data is formed. Next, when an even numbered image data (44-2 to 44-8) in the bank 45 is read out and transmitted to the light emitter array 1 after an appropriate timing, the image carrier has 45-1 to 44-8. Imaging spots based on the image data are formed in a line in the main scanning direction.

  Group B corresponds to pixels 9 to 16, and even numbered image data (24-10 to 24-16) in bank 25 and odd numbered image data (25-9 to 25-15) in bank 26 are included. Read out. Group C corresponds to pixels 17 to 24, and even-numbered image data (5-18 to 5-24) in bank 5 and odd-numbered image data (6-17 to 6-23) in bank 6. ) Is read out. Since the readout timing in the sub-scanning direction in the groups B and C is the same as that in the group A, detailed description thereof is omitted.

  Next, timing control in the sub-scanning direction between the groups A to C will be described. As described with reference to FIG. 18, the timing control between the groups is performed by first reading out the image data of the banks 45 and 46 corresponding to the group A and transmitting them to the light emitter array 1. Image forming spots arranged in a line are formed. Next, after a predetermined timing when the image carrier is moved in the sub-scanning direction, the image data of the banks 25 and 26 corresponding to the group B is read out and transmitted to the light emitter array 1, and the group A image is sent to the image carrier. The imaging spots are formed in the same row as the imaging spots arranged in a line according to the data. Further, after a predetermined timing, the image data of the banks 5 and 6 corresponding to the group C are read and transmitted to the light emitter array 1. In this manner, the image spots of group C are formed on the image carrier in the same row as the image spots of groups A and B in the main scanning direction.

  FIGS. 14 and 15 show memory tables at the next timing of the control corresponding to the MLA shown in FIGS. The bank 47 stores image data for skew correction. Group A corresponds to pixels 1 to 8, and even numbered image data (45-2 to 45-8) in bank 46 and odd numbered image data (46-1 to 46-7) in bank 47 are included. Read out. Group B corresponds to pixels 9 to 16, and even numbered image data (25-10 to 25-16) in bank 26 and odd numbered image data (27-9 to 27-15) in bank 27 are included. Read out. Group C corresponds to pixels 17 to 24, and even numbered image data (6-18 to 6-24) in bank 7 and odd numbered image data (7-17 to 7-23) in bank 8. ) Is read out.

  In the embodiment of the present invention, a tandem color printer that exposes four photoconductors with four line heads, simultaneously forms four color images, and transfers them onto one endless intermediate transfer belt (intermediate transfer medium). The target is a line head used in (image forming apparatus). FIG. 19 is a longitudinal side view showing an example of a tandem image forming apparatus using an organic EL element as a light emitting element. This image forming apparatus includes four light emitter arrays (line heads) 101K, 101C, 101M, and 101Y having the same configuration and four corresponding photosensitive drums (image carriers) 41K and 41C having the same configuration. , 41M and 41Y, respectively, and is configured as a tandem image forming apparatus.

  As shown in FIG. 19, this image forming apparatus is provided with a driving roller 51, a driven roller 52, and a tension roller 53. The tension roller 53 applies tension to the image forming apparatus and stretches it in the direction indicated by the arrow (counterclockwise). ) Is circulated to the intermediate transfer belt (intermediate transfer medium) 50. Photosensitive members 41K, 41C, 41M, and 41Y having photosensitive layers are arranged on the outer peripheral surface as four image carriers arranged at predetermined intervals with respect to the intermediate transfer belt 50.

  K, C, M, and Y added after the reference sign mean black, cyan, magenta, and yellow, respectively, and indicate that the photoconductors are black, cyan, magenta, and yellow, respectively. The same applies to other members. The photoreceptors 41K, 41C, 41M, and 41Y are rotationally driven in the direction indicated by the arrow (clockwise) in synchronization with the driving of the intermediate transfer belt 50. Around each photoconductor 41 (K, C, M, Y), charging means (corona charger) 42 (K) for uniformly charging the outer peripheral surface of the photoconductor 41 (K, C, M, Y), respectively. , C, M, Y) and the outer peripheral surface uniformly charged by the charging means 42 (K, C, M, Y) are synchronized with the rotation of the photoconductor 41 (K, C, M, Y). Thus, the above-described light emitter array (line head) 101 (K, C, M, Y) of the present invention for sequentially scanning the line is provided.

  Further, a developing device 44 that applies toner as a developer to the electrostatic latent image formed by the light emitter array (line head) 101 (K, C, M, Y) to form a visible image (toner image). (K, C, M, Y) and primary transfer as transfer means for sequentially transferring the toner image developed by the developing device 44 (K, C, M, Y) to the intermediate transfer belt 50 as a primary transfer target. A roller 45 (K, C, M, Y) and a cleaning device 46 (K, C) as a cleaning means for removing toner remaining on the surface of the photoconductor 41 (K, C, M, Y) after being transferred. C, M, Y).

  Here, in each light emitter array (line head) 101 (K, C, M, Y), the array direction of the light emitter array exposure head 101 (K, C, M, Y) is the photosensitive drum 41 (K, C). , M, Y) along the bus. Then, the emission energy peak wavelength of each light emitter array (line head) 101 (K, C, M, Y) and the sensitivity peak wavelength of the photoconductor 41 (K, C, M, Y) are substantially matched. Is set.

  The developing device 44 (K, C, M, Y) uses, for example, a non-magnetic one-component toner as a developer, and the one-component developer is conveyed to the developing roller by a supply roller, for example, and adhered to the developing roller surface. The film thickness of the developed developer is regulated by a regulating blade, and the developing roller is brought into contact with or increased in thickness by the photosensitive body 41 (K, C, M, Y), whereby the photosensitive body 41 (K, C, M, Y). The toner is developed as a toner image by attaching a developer according to the potential level.

  The black, cyan, magenta, and yellow toner images formed by the four-color single-color toner image forming station are intermediated by the primary transfer bias applied to the primary transfer roller 45 (K, C, M, Y). The toner image, which is sequentially primary transferred onto the transfer belt 50 and sequentially superposed on the intermediate transfer belt 50 to become a full color, is secondarily transferred to a recording medium P such as paper by a secondary transfer roller 66, and serves as a fixing unit. The toner is fixed on the recording medium P by passing through the fixing roller pair 61, and is discharged onto a paper discharge tray 68 formed in the upper part of the apparatus by a paper discharge roller pair 62.

  In FIG. 19, reference numeral 63 denotes a paper feed cassette in which a large number of recording media P are stacked and held, 64 denotes a pickup roller for feeding the recording media P one by one from the paper feed cassette 63, and 65 denotes a secondary transfer roller. A pair of gate rollers for defining the supply timing of the recording medium P to the secondary transfer portion 66, a secondary transfer roller 66 as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 50, 67 Is a cleaning blade as a cleaning means for removing the toner remaining on the surface of the intermediate transfer belt 50 after the secondary transfer.

  As described above, the image forming apparatus and the image forming method of the present invention have been described based on the principle and the embodiments, but the present invention is not limited to these embodiments and can be variously modified.

It is a block diagram which shows embodiment of this invention. It is a flowchart which shows the process sequence of this invention. It is a perspective view which shows the state in which the light-emitting body array was inclined and attached. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is a flowchart which shows the process sequence of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. It is explanatory drawing which shows embodiment of this invention. 1 is a schematic cross-sectional view showing an overall configuration of an embodiment of an image forming apparatus using an electrophotographic process of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Light emitter array, 2 ... Light emitting element, 3 ... Light emitting element row, 4 ... Light emitter block, 5 ... Micro lens, 6 ... Micro lens array (MLA), 10 ... Memory table, 20 ... Control device, 21 ... Skew correction control module, 22 ... MLA control module, 41 (K, C, M, Y) ... Photosensitive drum (image carrier) ), 42 (K, C, M, Y) ... Charging means (corona charger), 44 (K, C, M, Y) ... Developing device, 45 (K, C, M, Y). .... Primary transfer roller, 50 ... Intermediate transfer belt, 66 ... Secondary transfer roller, 101K, 101C, 101M, 101Y ... Light emitter array (line head)

Claims (9)

An image forming apparatus that simultaneously performs image formation of a plurality of colors on an image carrier using a plurality of line heads corresponding to each color,
A plurality of light emitting element rows arranged in the main scanning direction are arranged in the sub scanning direction to form a light emitter block, and a plurality of the light emitting blocks are arranged in the main scanning direction and the sub scanning direction, and each light emission A light emitter array (line head) in which a single lens having a negative optical magnification is associated with a body block;
Means for detecting an inclination with respect to a normal attachment position when the light emitter array is attached to the main body, means for creating skew correction image data according to the detected inclination of the light emitter array, and supplying to each light emitting element Storage means for storing image data to be performed, and control means for reading the image data from the storage means and transmitting the image data to the light emitting elements,
The position of the imaging spot formed on the image carrier by each light emitting element in the skew corrected image data is reversed in the main scanning direction by each light emitter block, and the control means stores the skew in the storage means. Stores corrected image data, controls reading of the skew-corrected image data stored in the storage means so as to be inverted in the sub-scanning direction within each of the light emitter blocks, and arranges a plurality of arrays in the sub-scanning direction The image forming apparatus is characterized in that reading is controlled so that the imaging spots formed by the respective light emitter blocks are arranged in a line in the main scanning direction of the image carrier. 2. The image forming apparatus according to claim 1, wherein the lenses are arranged in a plurality of rows in the sub-scanning direction while shifting the head position in the main scanning direction, and the light emitter block is associated with each lens. A memory table for storing the skew-corrected image data, wherein the memory table stores a plurality of horizontal columns for storing image data for each light emitting element arranged in a main scanning direction of the light emitter array; A plurality of vertical columns for storing image data for each light emitting element are formed in a matrix so as to form a plurality of imaging spots in the sub-scanning direction of the body, and the inclination of the light emitter array is detected. The control unit controls a write address of the skew-corrected image data to the memory table when the direction of the tilt and the magnitude of the tilt are detected by the unit. The image forming apparatus according to 2. The storage means has a second memory table having the same shape as the memory table storing the skew-corrected image data, and the control means sequentially stores the skew-corrected image data in the second memory table. 4. The readout of the skew-corrected image data from the second memory table is controlled so as to be inverted in the sub-scanning direction within each of the light emitter blocks. An image forming apparatus according to claim 1. The control means is configured for the light emitter blocks arranged in the sub-scanning direction based on the distance in the sub-scanning direction of the light emitting elements in the light emitter blocks and the moving speed of the image carrier. 5. The image forming apparatus according to claim 1, wherein timing for reading the skew-corrected image data from the second memory table is controlled. 6. The image forming apparatus according to claim 1, wherein the light emitting element is an organic EL element. 7. At least two image forming stations in which image forming units including a charging unit, a line head according to any one of claims 1 to 6, a developing unit, and a transfer unit are arranged around an image carrier. An image forming apparatus provided as described above, wherein the transfer medium passes through each station and forms an image by a tandem method. The image forming apparatus according to claim 7, further comprising an intermediate transfer member. An image forming method for simultaneously forming images of a plurality of colors using a plurality of line heads corresponding to each color,
A plurality of light emitting element rows arranged in the main scanning direction are arranged in the sub scanning direction to form a light emitter block, and a plurality of the light emitting blocks are arranged in the main scanning direction and the sub scanning direction, and each light emission Providing a light emitter array (line head) corresponding to a single lens having a negative optical magnification on the body block, detecting a tilt with respect to a normal attachment position when the light emitter array is attached to the main body, and the detection A step of creating skew-corrected image data according to the inclination of the light-emitting element array, and a position of an imaging spot formed on the image carrier, the skew-corrected image data as image data to be supplied to each light-emitting element Storing in the storage means so as to be inverted in the main scanning direction in each of the light emitter blocks, and the skew correction image data stored in the storage means The stage of controlling the reading so as to be reversed in the sub-scanning direction within the light block, and the imaging spots formed by each of the light emitter blocks arranged in the sub-scanning direction in one row in the main scanning direction of the image carrier And a step of controlling the reading so as to line up with the image forming method.

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