JP2009056612A - Control method for line head and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control method for a line head, whereby exposure displacement is corrected to improve image quality. <P>SOLUTION: The image processing section 27 of a print controller 21 image-processes image data corresponding to an amount of one page and transmits the image-processed data to a page memory control section (C plane)23. In the page memory control section 23, the image-processed data are separated according to each line of light emitting elements, and stored in page memories 24 to 26 corresponding to light emitting element group lines A to C. A request signal generating section 29 receives Vsync signal, generates a video data request signal (Vreq signal) to each plane and a line data request signal (HreqA-1) for each line of light emitting elements, and transmits them to the page memory control section. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for controlling a line head in which exposure position deviation is corrected and image quality deterioration is suppressed, and an image forming apparatus using the same.

  As an exposure light source for an image forming apparatus, a configuration in which a line head using LEDs is installed is known. Patent Document 1 describes an invention for correcting an exposure position shift of an LED line head in which light emitting elements are arranged in a staggered manner. In the present invention, the odd / even data is separated, and when writing data to the odd frame memory and the even frame memory, respectively, the write address is shifted and stored for the shifted row of the odd light emitting element row and the even light emitting element row. Then, in synchronization with one strobe signal (synchronized with the line data cycle), the exposure position shift between the odd dots and the even dots is corrected by sequentially reading and printing the data from the respective frame memories. Thus, the image quality is improved by correcting the exposure position deviation.

Japanese Patent No. 3233431

  In the example described in Patent Document 1, there is a problem that the line head driving circuit unit requires a frame memory control circuit for delaying data and a large-capacity frame memory, which increases the cost.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to control a line head that improves the image quality by correcting exposure misalignment while suppressing cost, and uses the same. Another object of the present invention is to provide an image forming apparatus.

  The line head control method of the present invention that achieves the above object includes a substrate and a plurality of light emitting elements arranged along the axial direction of the photosensitive member on the substrate, and a plurality of rows in a direction orthogonal to the axial direction of the photosensitive member. And a line head for forming a latent image at a different position for each light emitting element row with respect to the photoconductor, and a line data synchronization signal for each light emitting element row. Then, one linear latent image is formed in the axial direction of the photosensitive member.

  In the line head control method of the present invention, the line data synchronization signal is supplied to the driving circuit of the light emitting element row through a plurality of signal lines, and the pulse generation timing for driving the light emitting element row for each signal line is provided. Are different.

  In the line head control method of the present invention, the plurality of line data synchronization signals are supplied to the light emitting element row driving circuit through one signal line, and the light emitting element rows are controlled at a common pulse generation timing. It is characterized by doing.

  In the line head control method of the present invention, an imaging lens is provided corresponding to a plurality of light emitting element rows arranged in a direction orthogonal to the axial direction of the photoconductor, and the imaging lens is provided on the photoconductor. A light emitting element group row is formed by the plurality of light emitting element rows when a plurality of light emitting element rows are arranged in the axial direction, and a plurality of the light emitting element group rows are provided in a direction perpendicular to the axial direction of the photosensitive member. The image data memory corresponding to each of the above is provided.

  The line head control method of the present invention is characterized in that the image data memory is divided into memory areas for each of the light emitting element rows.

  In the line head control method according to the present invention, the image data memory is used in combination with a page memory for storing data after image processing.

The line head control method according to the present invention is characterized in that the CPU performs the memory area division for each light emitting element row.
It is characterized by that.

  The image forming apparatus according to the present invention includes an image forming station in which image forming units including a charging unit, a line head controlled by any of the above methods, a developing unit, and a transfer unit are arranged around an image carrier. At least two or more are provided, and the transfer medium passes through each of the image forming stations so that image formation is performed by a tandem method.

  The present invention will be described below with reference to the drawings. FIG. 6 is an explanatory diagram showing an embodiment of the present invention. 6A is a plan view partially showing the line head in a state in which the light emitting element group 6 is viewed through the imaging lens 4, and FIG. 6B is a relationship between the single imaging lens 4 and the light emitting element group 6. FIG. As shown in FIG. 6A, a plurality of light emitting element groups are arranged in correspondence with each imaging lens in the axial direction (main scanning direction) of the photosensitive member. The light emitting element group 6 is formed on a substrate.

  In the embodiment of the present invention, such a state in which a plurality of light emitting element groups are arranged in the axial direction of the photosensitive member is defined as a “light emitting element group row”. In FIG. 6A, a plurality of light emitting element group rows A, B, and C are arranged in a direction orthogonal to the axial direction of the photosensitive member. Each light emitting element group row AC forms a light emitter array. In the light emitting element groups adjacent to each other in the axial direction of the photosensitive member in each of the light emitting element group rows A to C, the lengths R, S, and T between the center positions are set equal. In addition, in the light emitting element groups of the respective light emitting element group rows A to C adjacent in the direction orthogonal to the axial direction of the photosensitive member, the lengths r, s, and t between the center positions are also set equal.

  In FIG. 6B, the light emitting element group 6 is provided with a light emitting element row 7a in which a plurality of light emitting elements are arranged in the axial direction of the photoreceptor. A plurality of the light emitting element rows are arranged in a direction orthogonal to the axial direction of the photosensitive member, and in the example of FIG. 6B, light emitting element rows 7a, 7b, and 7c are provided. As described above, FIGS. 6A and 6B describe that, for example, in the light emitting element group row A, three light emitting element rows 7a, 7b, and 7c are provided. The imaging lenses are also arranged in three rows in a direction orthogonal to the axial direction of the photosensitive member.

  FIG. 7 and FIG. 8 are explanatory diagrams of an example in which an exposure position shift occurs in the line head in which the imaging lens and the light emitting element group as shown in FIG. 6 correspond to each other. In FIG. 7, single coupled lenses 4, 5, and 8 are arranged at the head positions of the light emitting element group rows A to C, respectively. The pitch between coupled lens rows is Da and Db.

  As the coupling lens, a micro lens (ML) having a negative optical magnification is used, and a group of each ML forms a micro lens array (MLA). In such an MLA, an exposure position shift occurs due to individual differences in the pitch between MLA lens rows and the diameter of the photoconductor. When such an exposure position shift occurs, a latent image as shown in FIG. 8A is formed on the photoreceptor.

  In FIG. 8, reference numerals 6a, 6b and 6c denote patterns of latent images formed on the photoconductor when the MLA exposure position deviation is not corrected. Ta represents the MLA inter-lens exposure position shift, and Tb represents the MLA in-lens exposure position shift. Here, the distance between the lens rows represents a relationship between the lenses when a plurality of imaging lenses are arranged in a direction orthogonal to the axial direction of the photosensitive member. The latent image pattern 6a includes latent image rows k to n. The latent image pattern 6b includes latent image rows p to r, and the latent image pattern 6c includes latent image rows s to u.

  FIG. 8B is an explanatory diagram showing a latent image when the exposure position deviation of the MLA is corrected. At this time, the latent image 16 is formed on the photosensitive member like 17a to 17f by the output light transmitted through each ML. That is, the latent image is formed in one linear shape in the axial direction (main scanning direction) of the photosensitive member. For this reason, deterioration of image quality can be suppressed. In this correction, for example, the following processing is performed if the moving direction of the photosensitive member is Y. In the example of the latent image pattern 6a in FIG. 8A, the in-lens exposure position deviation correction is performed with the latent image row k as a reference. That is, the latent image sequence m is formed at a timing delayed by one row from the latent image sequence k. Further, the latent image row n is formed at a timing delayed by two rows from the latent image row k.

  Similarly, the latent image patterns 6b and 6c are also subjected to exposure position shift correction by delaying the latent image row by row. In the lens row exposure position correction, the latent image pattern 6b is delayed by one timing in the Y direction with reference to the latent image pattern 6a, and the latent image pattern 6c is delayed by two timings in the Y direction. Therefore, the actual exposure position deviation correction is formed by delaying the timing in the Y direction sequentially for each line image row m to u with reference to the latent image row k of the latent image pattern 6a.

  In the embodiment of the present invention, the in-lens exposure position shift and the inter-lens exposure position shift are thus corrected by controlling the operation timing of the light emitting element rows. Hereinafter, this embodiment will be described.

  FIG. 1 is a block diagram of a control unit in the embodiment of the present invention. In FIG. 1, a head controller 20, a print controller 21, and a mechanical controller 22 are provided as control means for the line head 10. The print controller 21 has an image processing unit 27, and the head controller 20 is provided with a line head control signal generation unit 28 and a request signal generation unit 29.

In FIG. 1, the configuration of the MLA and the light emitting elements is the same as described with reference to FIG. 6. The light emitting element group rows (lens rows) are three rows (A row, B row, C row), There are 3 rows (1 row, 2 rows, 3 rows). In the light emitting element group row A, the light emitting element rows 7a to 7c correspond to 1 to 3, respectively. Although only the C plane is shown in the print controller 21 in FIG. 1, the M, Y, and K planes have the same configuration.
In the embodiment of the present invention, a plurality of line data synchronization signals are transmitted to the line head and the print controller (Hreq signal to the print controller and ST signal to the line head).

  Next, the control procedure of FIG. 1 will be described. For conversion reasons, the circled numbers are written as ◯ 1. When printing is started, the image processing unit 27 of the print controller 21 performs image processing on image data for one page and transmits the image data to the page memory control unit (C plane) 23 (◯ 1). In the page memory control unit 23, the image processed data is separated for each light emitting element row and stored in the page memories 24 to 26 corresponding to the respective light emitting element group rows A to C.

  As described above, the page memories 24 to 26 store image processed data such as screen processing and color conversion. In addition, each of the page memories 24 to 26 is divided as an image data memory for each of the light emitting element rows 1 to 3. Thus, each page memory 24-26 is used together as an image data memory. When the image processed data is separated for each light emitting element row, it is desirable to process it by a separation circuit or a CPU.

  The mechanical controller 22 detects the edge of the printing paper with an optical sensor or the like, and transmits a video data synchronization signal (Vsync signal) to the request signal generation unit 29 of the head controller 20 (（2).

  The request signal generation unit 29 of the head controller 20 receives the Vsync signal, and receives a video data request signal (Vreq signal) for each plane and line data request signals (HreqA-1, HreqA-2) for each light emitting element row. HreqA-3,...) Is generated and transmitted to the page memory control unit of the print controller (◯ 3). The line data request signal functions as a line data synchronization signal that is synchronized with the line data cycle. In FIG. 1, the line data request signal (HreqA-1...) Is denoted as “3A-1,.

  At the same time, the request signal generation unit 29 transmits a line data request signal (◯ 3A-1,...) For each light emitting element row to the line head control signal generation unit 28, and each light emitting element group A of the line head 10. The driving circuit for each light emitting element row in .about.C is synchronized. The drive circuit for each light emitting element row will be described later with reference to FIG.

  The page memory control unit 23 transmits video data (VideoDataA-1...) For each light emitting element row to the line head in synchronization with each line data request signal (◯ 3A-1,...) ( ○ 4). In order to avoid complications, video data is also expressed as (◯ 4-1,...).

  The video data is formed for each light emitting element row in each light emitting element group A to C, and is transmitted to the corresponding light emitting element of the line head 10. Here, each line data request signal has a different pulse generation timing according to the exposure position deviation amount of the corresponding light emitting element row. Due to the difference in pulse generation timing, the exposure position deviation of each light emitting element row is corrected. Such timing control will be described with reference to the timing chart of FIG.

  The line head control signal generation unit 28 generates various signals (clock clk, strobe signal) for controlling the line head and transmits them to the line head (（5). Here, each strobe signal (ST_A-1, ST_A-2, ST_A-3,...) Is synchronized with each line data request signal (HreqA-1, HreqA-2, HreqA-3,...). ing.

  FIG. 2 is a circuit diagram showing an embodiment of the present invention. In FIG. 2, each light emitting element of the light emitting element rows 7a, 7b and 7c of the light emitting element group row A is controlled by the drive circuits 11a to 13b. Here, the drive circuits 11a and 11b control the light emitting elements in the light emitting element row 7a. The drive circuits 12a and 12b control the light emitting elements in the light emitting element row 7b, and the drive circuits 13a and 13b control the light emitting elements in the light emitting element row 7c. Reference numeral 14 denotes a power line.

  The clock signal is supplied to all the drive circuits 11a to 13b. Data signals A1 to A3 correspond to the video data (VideoData A-1 to A-3) in FIG. The data signal A1 is supplied to the drive circuits 11a and 11b, and the data signal A2 is supplied to the drive circuits 12a and 12b. The data signal A3 is supplied to the drive circuits 13a and 13b. Next, the strobe signal A1 is supplied to the drive circuits 11a and 11b, and the strobe signal A2 is supplied to the drive circuits 12a and 12b. The strobe signal A3 is supplied to the drive circuits 13a and 13b.

  Here, the strobe signals A1 to A3 are signals defining the time during which the light emitting elements are lit. In FIG. 2, different strobe signals are used for the respective light emitting element rows 7a to 7c. By performing such control, the exposure timing for each light emitting element row can be adjusted in units of clock frequency, and the exposure position deviation can be corrected with high accuracy. Although FIG. 2 shows only the driving circuit for the light emitting element group row A, the light emitting element group rows B and C have the same configuration.

  FIG. 3 shows a timing chart in the embodiment of the present invention. In FIG. 3, the notations such as signals ◯ 3A-1, ◯ 4A-1 correspond to the notations in FIG. That is, the signal ◯ 3A-1 represents HreqA-1, and the signal ◯ 4A-1 represents VideoDataA-1.

  As described in FIG. 1, the video data synchronization signal Vreq is output from the request signal generation unit 29. After the predetermined time, although not shown in FIG. 1, a line data synchronization signal Hsync signal is transmitted from the request signal generation unit 29 to the line head control signal generation unit 28 to synchronize the line head drive circuit with the line data cycle. Let The timing at which the Hsync signal is output is set as a reference time.

  The time Ta is delayed by two timings (two rows in the direction orthogonal to the axial direction of the photoconductor) from the operation of the light emitting element row 1 (7a in FIG. 7) of the light emitting element group row A (supply of VideoDataA-1). The time until the light emitting element row 2 is operated (supply of VideoData A-2). This time Ta corresponds to a time to delay the in-lens exposure position shift of the light emitting element row 2.

  The time Tb is delayed from the operation of the light emitting element row 1 of the light emitting element group row A by four timings (four lines in the direction orthogonal to the axial direction of the photosensitive member) to operate the light emitting element row 3 (VideoDataA-3 Supply time). This time Tb corresponds to a time to delay the in-lens exposure position shift of the light emitting element row 3.

  The time Tc is a delay time from the operation of the light emitting element row 1 of the light emitting element group row A to the operation of the light emitting element row 1 of the light emitting element group row B. This time is a time for delaying the exposure position by one lens in a direction orthogonal to the axial direction of the photosensitive member. In this example, it is delayed by 160 Hreq signals, and the inter-lens exposure position shift between the lens corresponding to the light emitting element group row A and the lens corresponding to the light emitting element group row B is corrected.

  The time Td is the time from the operation of the light emitting element row 1 of the light emitting element group row B to the operation of the light emitting element row 2 delayed by two timings (two lines in the direction orthogonal to the axial direction of the photosensitive member). . This time Td corresponds to a time for delaying the in-lens exposure position shift of the light emitting element row 2. The time Te is the time from the operation of the light emitting element row 1 of the light emitting element group row B to the operation of the light emitting element row 3 delayed by 4 timings (4 lines in the direction orthogonal to the axial direction of the photosensitive member). is there. This time Te corresponds to a time for delaying the in-lens exposure position shift of the light emitting element row 3.

  The time Tf is a delay time from the operation of the light emitting element row 1 of the light emitting element group row A to the operation of the light emitting element row 1 of the light emitting element group row C. This time is a time for delaying the exposure position by two lenses in a direction orthogonal to the axial direction of the photosensitive member. In this example, it is delayed by 320 Hreq signals, and the exposure position deviation between the lens corresponding to the light emitting element group row A and the lens corresponding to the light emitting element group row C is corrected.

  The time Tg is the time from the operation of the light emitting element row 1 of the light emitting element group row C to the operation of the light emitting element row 2 delayed by two timings (two lines in the direction orthogonal to the axial direction of the photosensitive member). . This time Tg corresponds to a time for delaying the in-lens exposure position shift of the light emitting element row 2. The time Th is the time from the operation of the light emitting element row 1 of the light emitting element group row C to the operation of the light emitting element row 3 delayed by 4 timings (4 lines in the direction orthogonal to the axial direction of the photosensitive member). is there. This time Th corresponds to a time for delaying the in-lens exposure position shift of the light emitting element row 3.

  As described with reference to FIG. 3, in the embodiment of the present invention, the operation position of each light emitting element row in the light emitting element group rows A, B, and C is controlled to correct the exposure position deviation in the lens. . Further, the operation timing of each light emitting element row between the light emitting element group rows A, B, and C is controlled to correct the exposure position deviation between the lenses. As described above, the exposure position deviation can be corrected with high accuracy by controlling the operation timing of the light emitting element. Here, the operation timing of each light emitting element row has the same cycle of the Hreq signal and different phases as shown in FIG.

  FIG. 4 is a block diagram illustrating a different embodiment of the present invention. The configuration of the MLA and the light emitting elements is that three light emitting element group rows (lens rows) (A row, B row, C row) and three light emitting element rows for each light emitting element group row (1 row, 2 rows, 3 rows). Line). In FIG. 4, only the C plane is shown, but the same configuration is applied to the M, Y, and K planes.

  When printing is started, the print controller 21 performs image processing on image data for one page and transmits it to the page memory control unit 23. The page memory control unit 23 separates the image processed data for each light emitting element row and stores them in the page memories 24 to 26 (◯ 1). When the image processed data is separated for each light emitting element row, it is desirable to process it by a separation circuit or a CPU.

  The mechanical controller 22 detects the edge of the printing paper with an optical sensor or the like, and transmits a video data synchronization signal (Vsync signal) to the request signal generation unit 29 of the head controller 20 (（2).

  The request signal generation unit 29 of the head controller 20 receives the Vsync signal, and receives a video data request signal (Vreq signal) for each plane and line data request signals (HreqA-1, HreqA-2) for each light emitting element row. HreqA-3,...) Is generated and transmitted to the page memory control unit 23 of the print controller 21 (◯ 3). At the same time, a line data synchronization signal (Hsync signal) is also transmitted to the line head control signal generator 38 to synchronize the line head drive circuit with the line data cycle (（3).

  The page memory control unit 23 transmits video data for each light emitting element row to the two line buffers 31 and 32 of the head controller in synchronization with each line data request signal. Here, each line data request signal has a different pulse transmission timing in accordance with the exposure position deviation amount of the corresponding light emitting element row. Due to the difference in the pulse transmission timing, the exposure position deviation of each light emitting element row is corrected.

  In the two-line buffers 31 and 32, the corrected video data for each light emitting element row is combined to generate one line data and transmit it to the line head 10 (◯ 5). Here, when the line buffer 31 is a write process, the line buffer 32 performs a read process. Conversely, when the line buffer 32 is a write process, the line buffer 31 performs a read process. By performing such processing, the difference in processing speed between the head controller 20 and the line head 10 is absorbed.

  The line head control signal generator 28 generates various signals (clock, strobe signal, start signal, etc.) for controlling the line head 10 and transmits them to the line head (（6).

  FIG. 5 is a circuit diagram corresponding to the embodiment of FIG. Here, the strobe signal is a signal that defines the time during which the light emitting elements are illuminated. In FIG. 5, since all the light emitting element rows use the same strobe signal, the adjustment of the exposure timing for each light emitting element row is performed in units of line data cycles. It becomes. For this reason, the exposure position deviation correction accuracy is inferior to that of the example of FIG. 1, but the wiring amount of the line head drive circuit can be reduced. In FIG. 5, the number of line data synchronization signals (strobe signals) transmitted to the head is one. In FIG. 5, 15a to 15f... Are drive circuits, and 14a to 14c are power supply lines. Each drive circuit 15a-15f is provided corresponding to each light emitting element group row A, B, C. The light emitting element rows (for example, 7a to 7c) in each light emitting element group row are configured to operate simultaneously as described above.

  In an embodiment of the present invention, a frame memory control circuit for delaying data to a line head drive circuit unit and a large-capacity frame when correcting an exposure position shift of an LED line head in which light emitting elements are arranged in a staggered manner Memory becomes unnecessary. Therefore, an inexpensive and high-quality image forming apparatus can be provided to the user.

  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. 9 is a longitudinal side view illustrating an example of a tandem image forming apparatus using an organic EL element as a light emitting element. In this image forming apparatus, four line heads 101K, 101C, 101M, and 101Y having the same configuration are exposed to four corresponding photosensitive members (image carriers) 41K, 41C, 41M, and 41Y having the same configuration. They are arranged at each position.

As shown in FIG. 9, this image forming apparatus is provided with a driving roller 51, a driven roller 52, and a tension roller 53. The intermediate transfer belt is circulated and driven by the tension roller 53 in the direction indicated by the arrow (counterclockwise). (Intermediate transfer medium) 50 is provided. Photosensitive members 41K, 41C, 41M, and 41Y are 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. The photoconductors 41 </ b> K to 41 </ b> Y are driven to rotate 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 42 (K, C, M, Y) and a line head 101 (K, C, M, Y) are provided.

  Further, a developing device 44 (K, C, M, Y) that applies a toner as a developer to the electrostatic latent image formed by the line head 101 (K, C, M, Y) to form a visible image; The primary transfer roller 45 (K, C, M, Y) and the cleaning device 46 (K, C, M, Y) are included. The emission energy peak wavelength of each line head 101 (K, C, M, Y) and the sensitivity peak wavelength of the photoconductor 41 (K, C, M, Y) are set to substantially coincide.

  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.

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

  In the embodiment of the present invention, an LED, an organic EL, a VCSEL (Vertical Cavity Surface Emitting Laser (Vertical Cavity Surface Emitting Laser)), or the like can be used as a light emitting element of the light emitter array. Moreover, as a lens array, SLA (Selfoc Lens Array), MLA (Micro Lens Array), etc. can be used.

  The line head control method and the image forming apparatus using the line head control method that corrects the exposure position deviation and suppresses the image quality deterioration of the present invention have been described based on the embodiments. However, the present invention is not limited to these embodiments. Various modifications are possible.

It is a block diagram which shows embodiment of this invention. It is a circuit diagram showing an embodiment of the present invention. It is a timing chart which shows embodiment of this invention. It is a block diagram which shows embodiment of this invention. It is a circuit diagram showing an embodiment of the present 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 the premise technique of this invention. 1 is a longitudinal side view of an image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

  4, 5, 8 ... imaging lens, 6 ... light emitting element group, 7a-7b ... light emitting element rows, 11-13 ... driving circuit, 14 ... power supply line, 20 ... Head controller, 21 ... print controller, 22 ... mechanical controller, 23 ... page memory controller, 28 ... line head control signal generator, 29 ... request signal generator, 41 (Y , M, C, K) ... photosensitive member, 101 (Y, M, C, K) ... line head, P ... recording medium, Y, M, C, K ... image forming station, A to C: Light emitting element group rows

Claims (8)

A plurality of light emitting elements arranged on the substrate along the axial direction of the photoconductor, and a light emitter array in which a plurality of light emitting element rows are arranged in a direction orthogonal to the axial direction of the photoconductor; A line head for forming a latent image at a different position for each light emitting element row with respect to the body, supplying a line data synchronization signal for each light emitting element row, and one linear latent signal in the axial direction of the photosensitive member. A method for controlling a line head, comprising forming an image. The line data synchronization signal is supplied to the driving circuit of the light emitting element row by a plurality of signal lines, and the pulse generation timing for driving the light emitting element row is different for each signal line. The control method of the line head as described. The plurality of line data synchronization signals are supplied to the drive circuit of the light emitting element row through one signal line, and the light emitting element row is controlled at a common pulse generation timing. Line head control method. An imaging lens is provided corresponding to a plurality of light emitting element rows arranged in a direction orthogonal to the axial direction of the photoconductor, and the plurality of rows when the plurality of imaging lenses are arranged in the axial direction of the photoconductor A light emitting element group row is formed by the light emitting element rows, a plurality of the light emitting element group rows are provided in a direction orthogonal to the axial direction of the photoconductor, and an image data memory corresponding to each of the light emitting element group rows is provided. A method for controlling a line head according to any one of claims 1 to 3. The in-head control method according to claim 4, wherein the image data memory is divided into memory areas for each of the light emitting element rows. 6. The in-head control method according to claim 4, wherein the image data memory is used in combination with a page memory for storing data after image processing. 7. The line head control method according to claim 5, wherein the memory area is divided for each light emitting element row by a CPU. An image forming unit including a charging unit, a line head controlled by the method according to any one of claims 1 to 7, a developing unit, and a transfer unit is disposed around the image carrier. An image forming apparatus, wherein at least two image forming stations are provided, and a transfer medium passes through each of the image forming stations to form an image in a tandem manner.

Images