JP2006035552A5 - - Google Patents

Description

Image forming apparatus, image forming method, and data control apparatus

The present invention relates to an image forming apparatus and method for forming a latent image by irradiating a latent image carrier with a light beam for forming a latent image. The present invention also relates to a data control apparatus suitable for the image forming apparatus and method.

This type of image forming apparatus includes a so-called tandem in which an image forming unit having a photoreceptor, an exposure unit, and a developing unit is provided for each of four different colors, for example, yellow, magenta, cyan, and black. Conventional image forming apparatuses are known. In this tandem apparatus, for example, as described in Patent Document 1 , toner images of respective color components are formed on a photoreceptor as follows. That is, for each color component, the light source of the exposure unit is controlled based on the image data indicating the toner image of the color component, and the light beam from the light source is scanned in the main scanning direction by the polygon mirror of the exposure unit. A latent image corresponding to the component image data is formed on the photoreceptor. The latent images are developed with corresponding color toners to form a plurality of color toner images, and the plurality of color toner images are superimposed on a transfer medium to form a color image.

Japanese Patent Laid-Open No. 1-170958 (page 4, FIG. 2)

  Incidentally, in the image forming apparatus, in order to obtain a high quality image, it is very important to adjust the position of the latent image formed on the photoconductor. For example, in an apparatus for forming a color image as described above, it is important to suppress a phenomenon in which toner images of respective color components are displaced from each other, that is, so-called color shift. Here, one of the main causes of color misregistration is that the scanning line is inclined with respect to a preset reference line, that is, the occurrence of skew. That is, ideally, the scanning line of the light beam scanned in the main scanning direction by the polygon mirror coincides with the reference line, and as a result, a line latent image is formed along the reference line on the photosensitive member. . However, the scanning line in each exposure unit is inclined with respect to the reference line, and color misregistration may occur. In view of this, the apparatus described in Patent Document 1 is provided with an adjustment mechanism for moving the optical path of the light beam by slightly moving some of the constituent elements of the exposure unit in two different axial directions. The movement can be adjusted. Then, by adjusting the movement of the scanning line at an appropriate timing, for example, after replacement of the photosensitive member, the position of the line latent image formed on the photosensitive member is moved to correct the color misregistration.

  However, in the conventional apparatus, some of the constituent elements of the exposure unit, for example, an optical box that accommodates a polygon mirror is mechanically moved and adjusted. Therefore, there is a certain limit in adjustment accuracy, and adjustment is performed with an accuracy of 1 pixel or less. It is virtually impossible to do. Therefore, there is a demand for a technique for further improving color misregistration and forming a high-quality image.

  As an image forming apparatus that forms a color image, there is a so-called four-cycle image forming apparatus in addition to the above-described tandem image forming apparatus. In this image forming apparatus, a process of transferring a toner image obtained by scanning a light beam onto a photosensitive member to form a latent image and developing the latent image with a toner onto a transfer medium such as an intermediate transfer belt is performed. The color (yellow, magenta, cyan and black) is repeated, and these four color toner images are superimposed on the transfer medium to form a color image. Even in such an apparatus, color misregistration is corrected by adjusting the latent image forming position of each color component with high accuracy, that is, resist correction is very important in forming a high-quality image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in a device equipped with a latent image forming unit that forms a latent image by scanning a light beam on the latent image carrier, a latent image formed on the latent image carrier. It is a first object of the present invention to provide a technique for forming a high-quality image by easily adjusting the formation position of the image with high accuracy.

  A second object of the present invention is to provide a data control apparatus suitable for achieving the first object.

In order to achieve the first object, an image forming apparatus according to the present invention irradiates a latent image carrier with a light beam from a light source through a vibrating deflection surface and forms a latent image on the latent image carrier. The second direction in which the scanning direction of the light beam is the first direction of the main scanning direction or the direction opposite to the first direction based on the latent image forming portion to be formed and information related to the position of the latent image formed on the latent image carrier A latent image forming unit that adjusts a latent image forming position on the latent image carrier in a scanning direction set by the direction control unit. It is characterized by.

According to another aspect of the present invention, there is provided an image forming method for forming a latent image by irradiating a latent image carrier with a light beam, and for achieving the first object , An information acquisition step for acquiring information related to the formation position of the latent image, and the scanning direction of the light beam based on the information obtained by the information acquisition step is the first direction of the main scanning direction or the reverse direction to the first direction. The latent image is developed while adjusting the formation position of the latent image in the direction setting step for selectively setting the second direction and the scanning direction set by the light beam by the vibrating deflection surface in the direction setting step. And an image forming process for forming a toner image .

In the invention (image forming apparatus and method) configured as described above, the light beam from the light source can be reciprocally scanned in the main scanning direction via the vibrating deflection surface. Here, the line latent image LI (+ X) is formed by the light beam scanned in the first direction of the main scanning direction, and the line latent image is formed by the light beam scanned in the second direction opposite to the first direction. Comparing with the case of forming LI (-X), the following can be understood. That is, as shown in FIG. 6, the two line latent images LI (+ X) and LI (−X) do not coincide with each other and are inclined in opposite directions. Therefore, by selectively setting the scanning direction of the light beam used for forming the latent image, the formation position of the line latent image on the latent image carrier can be adjusted by one pixel or less. Therefore, in the present invention, the line latent image is selectively set by setting the scanning direction of the light beam to the first direction or the second direction of the main scanning direction based on information relating to the position where the latent image is formed on the latent image carrier. The image forming position is adjusted with high accuracy, and as a result, a high-quality image can be formed.

In addition, according to the present invention, the light beam can be reciprocated and the scanning direction of the light beam is set by the direction control unit, so that the position where the line latent image is formed can be adjusted easily and quickly. can do. For example, the direction control unit may control the light emission timing of the light source of the latent image forming unit to set the scanning direction.

Here, “information relating to the position where the latent image is formed on the latent image carrier” refers to the position where the line latent image is formed when the line latent image is formed on the latent image carrier as described above. Means the information required to correct Examples of cases where correction is required in this way include, for example, a positional relationship between the latent image carrier and the latent image forming unit, a case where positional deviation due to temperature, vibration, etc. occurs, deterioration over time, and the like, and the latent image depends on the type of image. There are cases where it is desirable to correct the image forming position. Therefore, in order to cope with these, the following configuration may be adopted.

First, it further includes a storage unit that stores data indicating the positional relationship between the latent image carrier and the latent image forming unit as information, and the direction control unit sets the scanning direction of the light beam based on the data stored in the storage unit. You may comprise so that it may do. Here, when the line latent image formed on the latent image carrier when the relative positional relationship between the latent image carrier and the latent image forming unit is a preset reference positional relationship is used as a reference line, The data includes data indicating the shift amount of the line latent image with respect to the reference line.

The direction control unit further includes an information detection unit that detects an adjustment toner image formed to adjust the formation position of the latent image and obtains the amount of deviation of the line latent image with respect to a preset reference line as information. May be configured to set the scanning direction of the light beam based on the shift amount obtained by the information detection unit.

The information processing apparatus further includes an input unit that receives input of information and a storage unit that stores information input via the input unit, and the direction control unit is configured to transmit the latent image forming light beam based on the data stored in the storage unit. You may comprise so that a scanning direction may be set. Here, an adjustment image for adjusting the formation position of the latent image is formed, and the adjustment image is transferred to a recording medium so that the information can be visually judged, thereby facilitating grasping of the information, Accurate information input is possible.

Furthermore, when comparing a line drawing and a graphic image, the former is strongly influenced by color shift and jitter. Therefore, when an image including a line drawing is formed, it is desired to adjust the formation position of the line latent image according to the formation position of the line drawing to suppress the influence. Therefore, when an image including a line drawing area or a graphic area is formed, the position where the line drawing area is formed is used as information, and the direction control unit sets the scanning direction of the light beam for each line latent image based on the information. You may comprise.

By the way, in this type of image forming apparatus, in order to control the latent image forming operation, in the latent image forming unit, the second scanning is wider than the first scanning region corresponding to the effective image region on the latent image carrier. The area is scanned in the main scanning direction, and each image forming unit is provided with a synchronization detection unit for detecting the scanning light beam. However, it is desirable to arrange as follows. That is, in the image forming apparatus, a driving unit is provided to drive the surface of the latent image carrier in the sub scanning direction. In particular, in order to reduce the size of the apparatus, a driving means is mechanically connected to one end of the latent image carrier in the main scanning direction, and the driving means drives to one end of the latent image carrier. In many cases, the latent image carrier is driven by the transmission of force. For this reason, one end of the latent image carrier is more susceptible to mechanical vibration than the other end. Therefore, the following conditions:-The opposite side of the driving means in the main scanning direction (the other end side of the latent image carrier),
In the second scanning area and outside the first scanning area,
It is also possible to improve the image quality by suppressing the influence of mechanical vibration by disposing the synchronization detector at a position that satisfies these two conditions.

Further, in the above, the latent image forming operation is controlled by a signal detected on one end side in the main scanning direction, but in the second scanning region on each of both sides in the main scanning direction, and A synchronization detector that detects a scanning light beam that moves outside the first scanning region and outputs a signal is provided, and the latent image forming operation is controlled based on the detection signal output from the synchronization detector. Good. In this case, it is desirable to control the latent image forming operation based on the detection signal output from the synchronization detection unit arranged on the upstream side in the scanning direction of the light beam. Thereby, a detection signal is output on the light beam start point side, and the latent image forming operation is controlled using the detection signal.

  Further, in order to achieve the second object, the data control apparatus according to the present invention reads out the image information stored in the storage means for storing the image information constituting the one-line image data, and reads out the image information. It is characterized by comprising direction setting means for setting the order of controlling the light source based on the information based on the information relating to the position where the latent image is formed on the latent image carrier.

In the invention configured as described above, the order in which the image information stored in the storage means is read and the light source is controlled based on the image information is based on the information related to the formation position of the latent image on the latent image carrier. Is set . That is, the light emission timing of the light source of the latent image forming unit is controlled by the data control device to set the scanning direction of the latent image forming light beam. Therefore, facilitating the formation position of the line latent image, yet can you to quickly adjust.

<First Embodiment>
FIG. 1 is a diagram showing a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus of FIG. This image forming apparatus is a so-called tandem type color printer, and yellow (Y), magenta (M), cyan (C), and black (K) four-color photoconductors 2Y, 2M, and 2C as latent image carriers. 2K are arranged in the apparatus main body 5 side by side. The apparatus forms a full-color image by superimposing the toner images on the photoreceptors 2Y, 2M, 2C, and 2K, or forms a monochrome image using only the black (K) toner image. That is, in this image forming apparatus, when a print command is given to the main controller 11 from an external device such as a host computer in response to an image formation request from the user, an engine controller is responded to the print command from the CPU 111 of the main controller 11. 10 controls each part of the engine unit EG to form an image corresponding to a print command on a sheet S such as copy paper, transfer paper, paper, and an OHP transparent sheet.

  In the engine unit EG, a charging unit, a developing unit, an exposure unit, and a cleaning unit are provided for each of the four photoconductors 2Y, 2M, 2C, and 2K. As described above, for each toner color, an image forming unit is provided that includes a photoreceptor, a charging unit, a developing unit, an exposure unit, and a cleaning unit, and forms a toner image of the toner color. The configuration of these image forming means (photosensitive member, charging unit, developing unit, exposure unit, and cleaning unit) is the same for all color components. Therefore, the configuration relating to yellow will be described here, and the other color components will be described. Are denoted by corresponding reference numerals, and description thereof is omitted.

  The photoreceptor 2Y is rotatably provided in the arrow direction (sub-scanning direction) in FIG. More specifically, a drive motor MT is mechanically connected to one end of the photoreceptor 2Y. When a drive command is given from the CPU 101 to the motor control unit 105 electrically connected to the drive motor MT, the motor control unit 105 controls the drive motor MT. As a result, the photoreceptor 2Y rotates. Thus, in this embodiment, the photoconductor 2Y is driven by transmitting the driving force from the drive motor MT only to one end side of the photoconductor 2Y. In this embodiment, the arrangement position of the drive motor MT, the horizontal synchronization sensor 60 described later, and the scanning direction of the light beam are set to satisfy a predetermined relationship. This point will be described in detail later.

  A charging unit 3Y, a developing unit 4Y, and a cleaning unit (not shown) are arranged around the photosensitive member 2Y driven in this way along the rotation direction. The charging unit 3Y is composed of, for example, a scorotron charger, and uniformly charges the outer peripheral surface of the photoreceptor 2Y to a predetermined surface potential by applying a charging bias from the charging control unit 103. Then, a scanning light beam Ly is emitted from the exposure unit 6Y toward the outer peripheral surface of the photoreceptor 2Y charged by the charging unit 3Y. As a result, an electrostatic latent image corresponding to the yellow image data included in the print command is formed on the photoreceptor 2Y. Thus, the exposure unit 6Y corresponds to the “latent image forming unit” of the present invention, and operates in accordance with a control command from the exposure control unit 102Y (FIG. 4). The configuration and operation of the exposure unit 6 (6Y, 6M, 6C, 6K) and the exposure control unit 102 (102Y, 102M, 102C.102K) will be described in detail later.

  The electrostatic latent image formed in this way is developed with toner by the developing unit 4Y. The developing unit 4Y contains yellow toner. When a developing bias is applied from the developing device controller 104 to the developing roller 41Y, the toner carried on the developing roller 41Y partially adheres to each surface portion of the photoreceptor 2Y according to the surface potential. As a result, the electrostatic latent image on the photoreceptor 2Y is visualized as a yellow toner image. As the developing bias applied to the developing roller 41Y, a DC voltage or a voltage obtained by superimposing an AC voltage on the DC voltage can be used. In particular, the photosensitive member 2Y and the developing roller 41Y are spaced apart from each other. In a non-contact development type image forming apparatus that develops toner by flying toner with a voltage waveform in which an alternating voltage such as a sine wave, a triangular wave, or a rectangular wave is superimposed on a direct current voltage in order to efficiently fly the toner It is preferable that

  The yellow toner image developed by the developing unit 4Y is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer region TRy1. The color components other than yellow are also configured in exactly the same way as yellow, and a magenta toner image, a cyan toner image, and a black toner image are formed on the photoreceptors 2M, 2C, and 2K, respectively, and a primary transfer region. Primary transfer is performed on the intermediate transfer belt 71 by TRm1, TRc1, and TRk1, respectively.

  The transfer unit 7 includes an intermediate transfer belt 71 stretched between two rollers 72 and 73, and a belt driving unit (not shown) that rotates the intermediate transfer belt 71 in a predetermined rotation direction R2 by driving the roller 72 to rotate. ). Further, a secondary transfer roller 74 is provided at a position facing the roller 73 with the intermediate transfer belt 71 interposed therebetween, and is configured to be able to contact and separate with respect to the surface of the belt 71 by an electromagnetic clutch (not shown). Yes. When transferring a color image to the sheet S, the primary transfer timing is controlled to superimpose the toner images to form a color image on the intermediate transfer belt 71, and the color image is taken out from the cassette 8 and transferred to the intermediate transfer belt 71. The color image is secondarily transferred onto the sheet S conveyed to the secondary transfer region TR2 between the belt 71 and the secondary transfer roller 74. On the other hand, when a monochrome image is transferred to the sheet S, only the black toner image is formed on the photoreceptor 2K, and the monochrome image is secondarily transferred onto the sheet S conveyed to the secondary transfer region TR2. Further, the sheet S that has received the secondary transfer of the image in this way is conveyed toward the discharge tray portion provided on the upper surface portion of the apparatus main body via the fixing unit 9.

  The surface potential of each of the photoreceptors 2Y, 2M, 2C, and 2K after the toner image is primarily transferred to the intermediate transfer belt 71 is reset by a neutralizing unit (not shown), and the toner remaining on the surface is cleaned. Then, the next charging is performed by the charging units 3Y, 3M, 3C, and 3K.

  In the vicinity of the roller 72, a transfer belt cleaner 75, a density sensor 76 (FIG. 2), and a vertical synchronization sensor 77 (FIG. 2) are arranged. Among these, the cleaner 75 can be moved toward and away from the roller 72 by an electromagnetic clutch (not shown). Then, the blade of the cleaner 75 abuts on the surface of the intermediate transfer belt 71 that is stretched over the roller 72 while moving to the roller 72 side, and the toner that remains on the outer peripheral surface of the intermediate transfer belt 71 after the secondary transfer. Remove. The density sensor 76 is provided to face the surface of the intermediate transfer belt 71 and measures the optical density of the patch image formed on the outer peripheral surface of the intermediate transfer belt 71. Further, the vertical synchronization sensor 77 is a sensor for detecting the reference position of the intermediate transfer belt 71, and is a synchronization signal output in association with the rotational drive of the intermediate transfer belt 71 in the sub-scanning direction, that is, a vertical synchronization signal. It functions as a vertical sync sensor for obtaining Vsync. In this apparatus, the operation of each part of the apparatus is controlled based on the vertical synchronization signal Vsync in order to align the operation timing of each part and to superimpose toner images of each color accurately. Further, a color misregistration sensor 78 is disposed between the rollers 72 and 73, and detects the color misregistration amount of each color toner image.

  In FIG. 2, reference numeral 113 denotes an image memory provided in the main controller 11 for storing image data given from an external device such as a host computer via the interface 112, and reference numeral 106 is executed by the CPU 101. A ROM for storing calculation data, control data for controlling the engine unit EG, and the like, and a reference numeral 107 are RAMs for temporarily storing calculation results in the CPU 101 and other data. Reference numeral 108 denotes an FRAM (ferroelectric memory) for storing information on the usage status of each part of the engine.

  3 is a main scanning sectional view showing the structure of the exposure unit equipped in the image forming apparatus of FIG. 1, FIG. 4 is a view showing the scanning region of the light beam in the exposure unit of FIG. 3, and FIG. FIG. 3 is a diagram illustrating a signal processing block in one image forming apparatus. Hereinafter, the configurations and operations of the exposure unit 6 and the exposure control unit 102 will be described in detail with reference to these drawings. The configuration of the exposure unit 6 and the exposure control unit 102 is the same for all color components, so the configuration relating to yellow will be described here, and the other color components will be denoted by corresponding reference numerals and description thereof will be omitted.

  The exposure unit 6Y (6M, 6C, 6K) has an exposure housing 61. A single laser light source 62Y is fixed to the exposure housing 61, and a light beam can be emitted from the laser light source 62Y. The laser light source 62Y is electrically connected to a light source driving unit (not shown) of the exposure control unit 102Y shown in FIG. Then, the light source driving unit controls ON / OFF of the laser light source 62Y according to the image signal as follows, and a light beam modulated in accordance with the image data is emitted from the laser light source 62Y. Hereinafter, a description will be given with reference to FIG.

  In this image forming apparatus, when an image signal is input from an external device such as the host computer 100, the main controller 11 performs predetermined signal processing on the image signal. The main controller 11 includes functional blocks such as a color conversion unit 114, an image processing unit 115, two types of line buffers 116A and 116B, a direction switching unit 116C, a pulse modulation unit 117, a gradation correction table 118, and a correction table calculation unit 119. I have.

  In addition to the CPU 101, the ROM 106, the RAM 107, and the exposure control unit 102 shown in FIG. 2, the engine controller 10 detects a tone characteristic that detects a tone characteristic indicating the gamma characteristic of the engine unit EG based on the detection result of the density sensor 76. Part 123 is provided. In the main controller 11 and the engine controller 10, these functional blocks may be configured by hardware, or may be realized by software executed by the CPUs 111 and 101.

  In the main controller 11 to which the image signal is given from the host computer 100, the color conversion unit 114 converts the RGB gradation data indicating the gradation level of the RGB component of each pixel in the image corresponding to the image signal into the corresponding CMYK. Conversion into CMYK gradation data indicating the gradation level of the component. In this color conversion unit 114, the input RGB gradation data is, for example, 8 bits per pixel per color component (that is, representing 256 gradations), and the output CMYK gradation data is similarly 8 bits per pixel per color component ( That is, it represents 256 gradations). The CMYK gradation data output from the color conversion unit 114 is input to the image processing unit 115.

The image processing unit 115 executes the following processing for each color component. That is, gradation correction and halftoning processing are performed on the gradation data of each pixel input from the color conversion unit 114. That is, the image processing unit 115 refers to the gradation correction table 118 registered in advance in the non-volatile memory, and in accordance with the gradation correction table 118, the input gradation data of each pixel from the color conversion unit 114 is Conversion to corrected gradation data indicating the corrected gradation level is performed. The purpose of the gradation correction is to compensate for the change in the gamma characteristic of the engine unit EG configured as described above, and to keep the overall gamma characteristic of the image forming apparatus always ideal. In other words, in this type of image forming apparatus, the gamma characteristic of the apparatus varies from apparatus to apparatus, and even in the same apparatus, depending on the usage status. Therefore, in order to remove the influence of such gamma characteristic variations on the image quality, a gradation control process is executed to update the contents of the gradation correction table 118 based on the actual measurement result of the image density at a predetermined timing.

  In this gradation control process, for each toner color, a gradation patch gradation image prepared in advance for measuring the gamma characteristic is formed on the intermediate transfer belt 71 by the engine unit EG, and each gradation patch is obtained. The image density of the image is read by the density sensor 76, and based on a signal from the density sensor 76, the gradation characteristic detection unit 123 associates the gradation level of each gradation patch image with the detected image density ( The gamma characteristics of the engine unit EG are created and output to the correction table calculation unit 119 of the main controller 11. Then, the correction table calculation unit 119 compensates the actually measured gradation characteristic of the engine unit EG based on the gradation characteristic given from the gradation characteristic detection unit 123 to obtain an ideal gradation characteristic. The tone correction table data is calculated, and the content of the tone correction table 118 is updated to the calculation result. Thus, the gradation correction table 118 is changed and set. By doing so, this image forming apparatus can form an image with stable quality regardless of variations in gamma characteristics of the apparatus and changes over time.

The image processing unit 115 performs halftoning processing such as an error diffusion method, a dither method, and a screen method on the corrected gradation data thus corrected, and generates two types of halftone gradation data of 8 bits per pixel. Are input to the line buffers 116A and 116B. The content of the halftoning process varies depending on the type of image to be formed. That is, based on a determination criterion such as whether the image is a monochrome image, a color image, a line drawing, or a graphic image, the optimum processing content for the image is selected and executed.

These line buffers 116A and 116B are common in that they store halftone gradation data (image information) constituting one line image data output from the image processing unit 115. Is different. That is, the forward line buffer 116A outputs halftone gradation data constituting one line image data in the forward direction from the head, whereas the reverse line buffer 116B outputs in the reverse direction from the end. is there.

  The halftone gradation data output in this way is input to the direction switching unit 116C, and only the halftone gradation data output from one line buffer based on the direction switching signal is pulsed from the direction switching unit 116C at an appropriate timing. It is output to the modulation unit 117. The main reason for providing the two types of line buffers 116A and 116B in this way is to cope with the difference in the scanning direction of the latent image forming light beam for each color component, as will be described later. Also, the gradation data is input to the pulse modulation unit 117 at a timing and order corresponding to each color component by the direction switching unit 116C. Thus, in this embodiment, the line buffers 116A and 116B and the direction switching unit 116C correspond to the “direction control unit” and the “data control device” of the present invention.

  The gradation data after halftoning input to the pulse modulation unit 117 is a multilevel signal indicating the size and arrangement of toner dots of each color to be attached to each pixel, and the pulse modulation unit 117 that has received such data. Uses the halftone gradation data to create a video signal for pulse width modulating the exposure laser pulse of each color image of the engine unit EG, and outputs it to the engine controller 10 via a video interface (not shown). . Upon receiving this video signal, the light source driving unit (not shown) of the exposure control unit 102Y performs ON / OFF control of the laser light source 62Y of the exposure unit 6. The same applies to the other color components.

  Next, returning to FIGS. 3 and 4, the description will be continued. In the exposure housing 61, a collimator lens 631, a cylindrical lens 632, a deflector 65, and a scanning lens 66 are provided to scan and expose the light beam from the laser light source 62Y onto the surface (not shown) of the photoreceptor 2Y. It has been. That is, the light beam from the laser light source 62Y is shaped into collimated light of an appropriate size by the collimator lens 631, and then incident on the cylindrical lens 632 having power only in the sub-scanning direction Y. Then, by adjusting the cylindrical lens 632, the collimated light is imaged in the vicinity of the deflection mirror surface 651 of the deflector 65 in the sub-scanning direction Y. Thus, in this embodiment, the collimator lens 631 and the cylindrical lens 632 function as the beam shaping system 63 that shapes the light beam from the laser light source 62Y.

  The deflector 65 is formed by using a micromachining technique in which a micromachine is integrally formed on a semiconductor substrate by applying a semiconductor manufacturing technique, and includes a vibrating mirror that resonates and oscillates. That is, in the deflector 65, the light beam can be deflected in the main scanning direction X by the deflecting mirror surface 651 that resonates and vibrates. More specifically, the deflecting mirror surface 651 is pivotally supported around a swing shaft (torsion spring) that is substantially orthogonal to the main scanning direction X, and responds to an external force applied from an operating portion (not shown). Swings sine around the swing axis. This actuating unit applies an electrostatic, electromagnetic or mechanical external force to the deflection mirror surface 651 based on a mirror drive signal from a mirror drive unit (not shown) of the exposure control unit 102 to mirror the deflection mirror surface 651. Swing at the frequency of the drive signal. Note that any driving method such as electrostatic adsorption, electromagnetic force, or mechanical force may be adopted as the driving method by the operating unit, and since these driving methods are well known, description thereof is omitted here.

The light beam deflected by the deflecting mirror surface 651 of the deflector 65 is deflected toward the scanning lens 66 at the maximum amplitude angle θmax as shown in FIG. In this embodiment, the scanning lens 66 is configured so that the F values are substantially the same in the entire effective image region IR of the photoreceptor 2. Accordingly, the light beam deflected toward the scanning lens 66 is focused on the effective image area IR on the surface of the photosensitive member 2 through the scanning lens 66 with substantially the same spot diameter. Thereby, a line-shaped latent image extending in the main scanning direction X is formed on the effective image region IR of the photosensitive member 2 by scanning the light beam in parallel with the main scanning direction X. In this embodiment, the scanning area (second scanning area) SR2 that can be scanned by the deflector 65 is a scanning area (first area) for scanning a light beam on the effective image area IR as shown in FIG. Scanning area) is set wider than SR1. Further, the first scanning region SR1 is located at a substantially central portion of the second scanning region SR2, and is substantially symmetric with respect to the optical axis. Further, the symbol θir in the figure indicates the amplitude angle of the deflection mirror surface 651 corresponding to the end of the effective image region IR, and the symbol θs indicates the amplitude angle of the deflection mirror surface 651 corresponding to the horizontal synchronization sensor described below. Show.

  Further, in the apparatus configured as described above, the light beam can be reciprocated in the main scanning direction, that is, the light beam can be scanned in both the (+ X) direction and the (−X) direction. . As described above, the gradation data constituting one line image data is temporarily stored in the storage unit (line buffers 116A and 116B), and the direction switching unit 116C receives the gradation data at an appropriate timing and order. The pulse modulation unit 117 is provided. For example, when the direction is changed to the (+ X) direction, as shown in FIG. 6A, the beam spot is read out from the line buffer 116A in the order of gradation data DT1, DT2,. Is irradiated onto the photoconductor 2 in the first direction (+ X) to form a line latent image LI (+ X). On the other hand, when the direction is switched to the (−X) direction, as shown in FIG. 6B, the grayscale data DTn, DT (n−1),. A beam spot is irradiated onto the photoconductor 2 in the second direction (−X) based on each gradation data, and a line latent image LI (−X) is formed. Therefore, the light beam for forming a latent image (corresponding to the “latent image forming light beam” of the present invention) can be made different for each color component or for each line as follows. More specifically, in this embodiment, the skew information resulting from the relative positional relationship between the photosensitive member and the exposure unit deviating from the reference positional relationship for each color component is the “latent image on the latent image carrier” of the present invention. The information is stored in advance in the FRAM 108 as “information relating to the image forming position”. Based on the skew information, in magenta and black, the light beam SL1 that scans the first scanning region SR1 in the (+ X) direction is guided to the effective image region IR to form a latent image in the effective image region IR (FIG. 4 and FIG. 8). On the other hand, for yellow and cyan, the light beam SL2 that scans the first scanning region SR1 in the (−X) direction is guided to the effective image region IR to form a latent image in the effective image region IR (see FIGS. 4 and 4). 9). This point will be described in detail later.

  In this embodiment, the scanning direction and the arrangement position of the drive motor MT are set in advance so as to satisfy the following relationship. That is, the drive motor MT is disposed on the downstream side in the scanning direction (+ X). Also, as shown in FIG. 3, the end of the scanning path of the scanning light beam is guided to the horizontal synchronization sensor 60 by the folding mirror 69 on the upstream side in the scanning direction (+ X). The folding mirror 69 is disposed at the end of the second scanning region SR2 on the upstream side in the scanning direction (+ X). The folding mirror 69 is located in the second scanning region SR2 and on the first scanning region SR1 on the upstream side in the scanning direction (+ X). The scanning light beam that moves outside the position is guided to the horizontal synchronization sensor 60. A signal is output from the horizontal synchronization sensor 60 at a timing when the scanning light beam is received by the horizontal synchronization sensor 60 and passes through the sensor position (amplitude angle θs). Thus, in this embodiment, the horizontal synchronization sensor 60 is used as a horizontal synchronization reading sensor for obtaining a synchronization signal when the light beam scans the effective image area IR in the main scanning direction X, that is, the horizontal synchronization signal Hsync. The latent image forming operation is controlled based on the horizontal synchronization signal Hsync. Hereinafter, a latent image forming operation in the apparatus according to the present embodiment will be described.

FIG. 7 is a flowchart showing the operation of the image forming apparatus in the first embodiment. FIG. 8 is a schematic diagram for explaining skew information stored in the FRAM. Further, FIG. 9 is a diagram showing a latent image formed by the latent image forming operation of the present embodiment. 8 and 9 is an imaginary line indicating the trajectory of the scanning line, and a thick arrow indicates a scanning light beam for forming a latent image. Here, the relative positional relationship is not the same between the photosensitive member and the exposure unit for each color component, as shown in FIG. 8, skew condition on each color component is different. That is, when the latent image is formed by the latent image forming light beam SL1 scanned in the same direction (+ X) for all the color components, the yellow and cyan line latent images LIy and LIc on the paper surface of FIG. The magenta and black line latent images LIm and LIk are inclined clockwise with respect to the reference line RL, while being inclined counterclockwise with respect to the reference line RL indicating the positional relationship. Therefore, the skew information for yellow and cyan is set to (−1), while the skew information for magenta and black is set to (+1) and is stored in the FRAM 108 in advance. Such skew information can be stored in the FRAM 108 after being verified in advance at the factory shipment stage, for example. Note that the content of the skew information is not limited to this embodiment, and is arbitrary as long as the information indicates the skew state.

  When an image signal is input from an external device such as the host computer 100, a latent image is formed on each photoconductor according to the flowchart shown in FIG. 7, and a color image is formed based on each latent image. That is, in step S11, skew information is read from the FRAM 108 (information acquisition step). Then, the scanning direction of the latent image forming light beam is determined corresponding to each skew information (step S12). In this embodiment, when the skew information is “+1”, the first direction (+ X) is set as the scanning direction, while when the skew information is “−1”, the second direction (−X) is set as the scanning direction (direction). Decision process).

  Next, a direction switching signal corresponding to the scanning direction determined as described above is given to the direction switching unit 116C of the main controller 11 (step S13). Thus, the scanning direction of the latent image forming light beam is instructed for each color component and one line image data. On the other hand, upon receiving these instructions, the direction switching unit 116C applies gradation data from the line buffer corresponding to the skew information to the pulse modulation unit 117 at an appropriate timing and order, and scans the photosensitive member with the latent image forming light beam. (Step S14). In this embodiment, since the magenta and black skew information is set to (+1) as described above, the line latent images LIm and LIk are formed using the light beam SL1 scanned in the (+ X) direction. . Conversely, since the skew information for yellow and cyan is set to (-1), the line latent images LIy and LIc are formed using the light beam SL2 scanned in the (-X) direction. As a result, as shown in FIG. 9, each line latent image LIy, LIm, LIc, LIk coincides with or is inclined in the same direction with respect to the reference line RL common to the image forming means, thereby correcting the color misregistration. Can do. The latent image formed in this manner is developed in each image forming unit to form a four-color toner image, and is superimposed on the intermediate transfer belt 71 to form a color image.

  As described above, according to this embodiment, by selectively switching the scanning direction of the light beam (latent image forming light beam) used for latent image formation based on the skew information, the line latent image on the photosensitive member is changed. The formation position can be adjusted with high accuracy at 1 pixel or less. As a result, it is possible to form a high-quality color image. Further, the gradation data constituting one line image data is temporarily stored in the storage unit (line buffers 116A and 116B), and the gradation data is read at the timing and order corresponding to the skew information by the direction switching unit 116C. Thus, the scanning direction of the latent image forming light beam is switched. Therefore, the formation position of the line latent image can be switched easily and quickly.

In this embodiment, the drive motor MT is mechanically connected to the end of the photoconductor 2 on the downstream side in the first direction (+ X) as shown in FIG. Therefore, one end portion of the photosensitive member 2 is more susceptible to mechanical vibration than the other end portion. Therefore, in the present embodiment, the following two conditions, that is,
The opposite side of the drive motor MT in the main scanning direction X (the other end side of the photoreceptor 2),
In the second scanning region SR2 and out of the first scanning region SR1,
The horizontal synchronization sensor 60 is disposed at a position satisfying these two conditions. As described above, since the sensor 60 corresponding to the “ synchronization detection unit” is disposed at a position that is not easily affected by the mechanical vibration, the horizontal synchronization signal can be obtained in a state where the influence of the mechanical vibration is suppressed. As a result, the latent image can be formed satisfactorily and the image quality can be improved.

Second Embodiment
In the first embodiment, the scanning direction of the latent image forming light beam is selectively switched based on preset skew information. However, an adjustment toner image (registration mark) for adjusting the latent image forming position is selected. ) And the amount of shift of the line latent image (color shift amount) with respect to a preset reference line by detecting the adjustment toner image by the color shift sensor 78 is set to “a latent image on the latent image carrier” of the present invention. You may make it obtain | require as "information relevant to the formation position of an image." Thus, in the second embodiment, the color misregistration sensor 78 functions as an “ information detection unit”. Since the basic configuration of the apparatus is the same as that of the first embodiment, the switching method will be mainly described here. In this regard, the same applies to third and fourth embodiments described later.

  FIG. 10 is a flowchart showing a second embodiment of the present invention. In the second embodiment, first, predetermined registration marks are formed by the respective image forming units in step S 21, and these registration marks are transferred to the intermediate transfer belt 71. Then, each registration mark is detected by the color misregistration sensor 78 (step S22). Thereby, the shift amount of the line latent image with respect to the reference line is obtained (information acquisition step). Here, a reference line virtually determined in advance may be adopted for the reference line, or a specific color of four colors may be set in advance and the scanning line of the specific color may be used as the reference line. Good. In any case, the relative color shift amount of the line latent image in each color component can be accurately obtained. Since the technical content for obtaining the color misregistration amount using the registration mark is already well known, detailed description is omitted here.

  When the color misregistration amount is thus obtained for each color component, the scanning direction of the latent image forming light beam is determined based on the color misregistration amount (step S23). For example, when the color misregistration state is the state shown in the lower part of FIG. 8, the first direction (+ X) is set for magenta and black, while the second direction (−X) is set for yellow and cyan. It is set (direction determining step).

  When an image signal is input from an external device such as the host computer 100, a direction switching signal corresponding to the scanning direction determined as described above is provided to the direction switching unit 116C of the main controller 11 (step S24). Thus, the scanning direction of the latent image forming light beam is instructed for each color component and one line image data. On the other hand, upon receiving these instructions, the direction switching unit 116C applies gradation data from the line buffer corresponding to the skew information to the pulse modulation unit 117 at an appropriate timing and order, and scans the photosensitive member with the latent image forming light beam. (Step S25). As a result, for example, as shown in FIG. 9, each line latent image LIy, LIm, LIc, LIk coincides with or is inclined in the same direction with respect to a reference line RL common to the image forming means, and color misregistration is corrected. be able to. The latent image formed in this manner is developed in each image forming unit to form a four-color toner image, and is superimposed on the intermediate transfer belt 71 to form a color image.

  As described above, also in the second embodiment, as in the first embodiment, by selectively switching the scanning direction of the latent image forming light beam based on the color misregistration amount, the line latent image on the photoconductor is changed. The formation position can be adjusted with high accuracy at 1 pixel or less, and as a result, a high-quality color image can be formed. Further, since the registration mark is formed, and the registration direction is detected and the amount of color misregistration is obtained to perform the switching setting of the scanning direction, the scanning direction can always be optimized. Accordingly, even when the color misregistration state changes with time, a high-quality color image can be stably formed.

<Third Embodiment>
Further, as a method for detecting the color misregistration amount, an adjustment chart described in, for example, Japanese Patent Application Laid-Open No. 9-304992 may be used in addition to the method using a registration mark. Hereinafter, the third embodiment of the present invention will be described in detail with reference to FIG.

  FIG. 11 is a flowchart showing the third embodiment of the present invention. In the third embodiment, first, an adjustment chart is printed in step S31. Here, three patterns suitable for detecting the color misregistration amount are printed on the adjustment chart. Then, using the adjustment chart, the service engineer or the user obtains the color misregistration amount by visual judgment. If it is determined that color misregistration correction is necessary, an adjustment value for correcting color misregistration is input from an input device of a host computer connected to the image forming apparatus. As described above, in this embodiment, the adjustment value is input as “information related to the position where the latent image is formed on the latent image carrier” via the I / F 112. Therefore, in this embodiment, the I / F 112 corresponds to the “input unit” of the present invention. Of course, it goes without saying that the adjustment value may be input via an input panel (not shown) provided in the apparatus.

  When the adjustment value is thus input (step S32; information acquisition step), the adjustment value is already rewritten and updated (step S33). On the other hand, if no adjustment value is input, the process proceeds to step S34. In step S34, the scanning direction of the latent image forming light beam is determined based on the adjustment value (direction determining step). For example, the service engineer sets (+1) as an adjustment value for magenta and black and (-1 as an adjustment value for yellow and cyan) in response to the color misregistration state shown in the lower part of FIG. ) May be set. In this case, the first direction (+ X) is set for magenta and black, while the second direction (−X) is set for yellow and cyan. Note that the content of the adjustment value is not limited to this, and is arbitrary as long as it is information indicating the adjustment value.

  When an image signal is input from an external device such as the host computer 100, a direction switching signal corresponding to the scanning direction determined as described above is provided to the direction switching unit 116C of the main controller 11 (step S35). Thus, the scanning direction of the latent image forming light beam is instructed for each color component and one line image data. On the other hand, upon receiving these instructions, the direction switching unit 116C applies gradation data from the line buffer corresponding to the skew information to the pulse modulation unit 117 at an appropriate timing and order, and scans the photosensitive member with the latent image forming light beam. (Step S36). As a result, for example, as shown in FIG. 9, each line latent image LIy, LIm, LIc, LIk coincides with or is inclined in the same direction with respect to a reference line RL common to the image forming means, and color misregistration is corrected. be able to.

  The latent image formed in this manner is developed in each image forming unit to form a four-color toner image, and is superimposed on the intermediate transfer belt 71 to form a color image.

  As described above, also in the third embodiment, as in the first and second embodiments, the line latent image on the photosensitive member is selectively switched by selectively switching the scanning direction of the latent image forming light beam based on the adjustment value. The image formation position can be adjusted with high accuracy with one pixel or less, and as a result, a high-quality color image can be formed. In addition, since the scanning direction switching setting is performed based on the adjustment value input based on the adjustment chart reflecting the color misregistration state, the scanning direction can be optimized every time the adjustment chart is created. Accordingly, even when the color misregistration state changes with time, a high-quality color image can be stably formed.

<Fourth embodiment>
Incidentally, in the first and second embodiments, the image quality is improved by adjusting the scanning direction of the latent image forming light beam based on the skew information. However, a color image is formed by superimposing a plurality of color toner images. In the image forming apparatus for forming the image, the registration error also has an important influence on the image quality. For example, when a speed fluctuation occurs in the photosensitive member or the intermediate transfer belt, a registration shift occurs between the toner image transferred at that time and the toner image already transferred to the intermediate transfer belt. Even if there is no speed fluctuation in the photoconductor, etc., if the rotation cycle of the photoconductor rotating and moving in the sub-scanning direction is not an integral multiple of the scanning cycle of the light beam scanned in the main scanning direction, each color This toner image has a disadvantage that registration deviation of one scanning at maximum occurs in the sub-scanning direction. Therefore, it is very important to correct the registration shift by adjusting the latent image forming position of each color component with high accuracy in forming a high quality image. In addition, in a tandem image forming apparatus, skew and resist misalignment may occur in combination. For this reason, it is desired to comprehensively judge these to suppress color misregistration. Hereinafter, the fourth embodiment will be described in detail with reference to FIG.

  FIG. 12 is a flowchart showing the fourth embodiment of the present invention. In the fourth embodiment, first, skew information is obtained in step S41. In other words, the skew information may be read from the FRAM 108 as in the first embodiment, or the skew information may be obtained by forming and detecting a registration mark as in the second embodiment.

  Further, as is already known in the color image forming apparatus, correction information necessary for correcting the registration deviation is stored in advance in a memory such as the ROM 106 or the FRAM 108 as a registration control amount. Therefore, in this embodiment, in addition to the skew information, the registration control amount is read from the memory as “information relating to the position where the latent image is formed on the latent image carrier” of the present invention (step S42). Thus, in the present embodiment, steps S41 and S42 correspond to the “information acquisition process” of the present invention.

  In the next step S43, the scanning direction of the latent image forming light beam is determined based on the skew information and the resist control amount. That is, when skew and registration error occur, color misregistration appears as a total result of both. In this embodiment, since the scanning direction of the light beam is not determined based on one information, but is comprehensively determined based on both, a scanning direction corresponding to the color shift appearing as a comprehensive result is obtained ( Direction determination step).

  When an image signal is input from an external device such as the host computer 100, a direction switching signal corresponding to the scanning direction determined in step S43 is provided to the direction switching unit 116C of the main controller 11 as in the above embodiment. (Step S44). Thus, the scanning direction of the latent image forming light beam is instructed for each color component and one line image data. On the other hand, upon receiving these instructions, the direction switching unit 116C applies gradation data from the line buffer corresponding to the skew information to the pulse modulation unit 117 at an appropriate timing and order, and scans the photosensitive member with the latent image forming light beam. (Step S45). As a result, it is possible to correct the color misregistration that appears as an overall result of skew and registration error. The latent image formed in this manner is developed in each image forming unit to form a four-color toner image, and is superimposed on the intermediate transfer belt 71 to form a color image.

  As described above, also in the fourth embodiment, similarly to the above embodiment, the skew information and the resist control amount are obtained as “information related to the formation position of the latent image on the latent image carrier” of the present invention. By selectively switching the scanning direction of the light beam for forming the latent image based on the information of the image, the formation position of the line latent image on the photosensitive member can be adjusted with high accuracy with one pixel or less, resulting in high quality. It is possible to form a simple color image.

<Fifth Embodiment>
As an image forming apparatus for forming a color image, there is, for example, a four-cycle image forming apparatus shown in FIG. 13 in addition to the above-described tandem image forming apparatus. Also in this image forming apparatus, by applying the present invention, it is possible to correct the registration error and improve the image quality. Hereinafter, this will be described in detail with reference to FIGS. 13 and 14.

  FIG. 13 is a diagram showing an image forming apparatus according to a fifth embodiment of the invention. This apparatus is basically the same as the apparatus shown in FIG. 1 except that it is a so-called four-cycle image forming apparatus. That is, in this apparatus, a rotary developing unit 4 having four developing devices 4Y, 4M, 4C, and 4K is provided for one photoconductor 2. Then, one of the developing devices 4Y, 4M, 4C, and 4K is selectively positioned at a developing position facing the photoconductor 2 in accordance with the latent image formed on the photoconductor 2 and developed by the selective developing device. The process of transferring the toner image to the transfer medium is repeated for four colors of yellow, magenta, cyan, and black, and the four color toner images are superimposed on the intermediate transfer belt 71 to form a color image. Since the other basic configurations are the same, the same or corresponding reference numerals are given and description thereof is omitted.

  By the way, in the image forming apparatus of FIG. 13, since the toner image of each color is formed using the single photoconductor 2 and the single exposure unit 6, the color misregistration caused by the skew is not basically a problem. . However, the above-described resist misalignment may occur. Therefore, in the fifth embodiment, the image quality is improved by correcting the registration error by executing the operation shown in FIG. In this embodiment, correction information necessary for correcting the registration error is stored in advance in a memory such as the ROM 106 or the FRAM 108 as a registration control amount. Further, since methods for obtaining correction information, registration control amount, and the like are already known, detailed description thereof is omitted here.

  FIG. 14 is a flowchart showing a fifth embodiment of the present invention. In the fifth embodiment, steps S51 to S54 are repeated for each color. That is, the registration control amount is read from the memory as “information relating to the position where the latent image is formed on the latent image carrier” of the present invention (step S51; information acquisition step). In the next step S52, the scanning direction of the latent image forming light beam is determined based on the registration control amount (direction determining step). Then, a latent image corresponding to an image signal given from an external device such as the host computer 100 is formed on the photoreceptor 2. At this time, as in the above embodiment, a direction switching signal corresponding to the scanning direction determined in step S52 is provided to the direction switching unit 116C of the main controller 11 (step S53). Thus, the scanning direction of the latent image forming light beam is instructed for each color component and one line image data. On the other hand, upon receiving these instructions, the direction switching unit 116C applies gradation data from the line buffer corresponding to the skew information to the pulse modulation unit 117 at an appropriate timing and order, and scans the photosensitive member with the latent image forming light beam. (Step S54). As a result, a first color latent image is formed. The latent image formed in this way is developed with toner, and then the toner image is transferred to the intermediate transfer belt 71.

  Further, while a series of processing (steps S51 to S54) is not executed for all the color components in step S55, the process returns to step S51 and a series of processing is executed for the next color component, and each color is transferred onto the intermediate transfer belt 71. The toner images are superimposed to form a color image.

  As described above, according to the fifth embodiment, the resist control amount is obtained as “information related to the position of forming the latent image on the latent image carrier” of the present invention, and the latent image forming light beam is based on the information. By selectively switching the scanning direction, the formation position of the line latent image on the photosensitive member 2 can be adjusted with high accuracy with one pixel or less. As a result, the registration error is corrected and a high-quality color image is corrected. Can be formed.

<Sixth Embodiment>
FIG. 15 is a view for explaining a sixth embodiment of the image forming apparatus according to the present invention. FIG. 16 is a view showing a line latent image formed by the image forming apparatus according to the sixth embodiment. For example, as shown in FIG. 15, an image to be printed by the image forming apparatus may include a plurality of types such as line drawings and graphic images. On the sheet S shown in FIG. 15, line drawings LM1 to LM3 such as text and graphic images GI1 to GI3 are mixed and printed. Here, when the line drawing and the graphic image are compared, the former is strongly influenced by color shift and jitter. Further, the line drawing and the graphic image may be arranged in parallel in the sub-scanning direction Y. In this case, it is desirable to adjust the line latent image formation position in accordance with the line drawing formation position to suppress the influence of color misregistration and the like.

  FIG. 15 shows a graphic area AR1 in which only the graphic image GI1 is formed, a line drawing area AR2 in which only a line drawing LM1 such as text is formed, and two mixed areas AR3 and AR4. Among these, in the mixed area AR3, the graphic image GI2 is arranged in the direction (+ X), and the line drawing LM2 is arranged in the direction (-X). Accordingly, in consideration of the color shift of the line image LM2, the line image LM2 can be formed using the light beam in the initial scanning stage by using the latent image forming light beam SL1 scanned in the (+ X) direction. Further, the line drawing LM2 can be formed more satisfactorily by aligning the writing positions. On the other hand, in the mixed area AR4, the graphic image GI3 is arranged in the direction (-X), and the line drawing LM3 is arranged in the direction (+ X). Therefore, it is desirable to use the latent image forming light beam SL2 scanned in the (-X) direction, contrary to the above.

  In this way, when an image including a line drawing area or a graphic area is formed, for example, as shown in FIG. 16, the scanning direction of the latent image forming light beam is changed according to the position where the line drawing area is formed. It is desirable to switch every time.

  <Others>

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above embodiment, the latent image forming operation is controlled based on the horizontal synchronization signal detected on the opposite side of the drive motor MT in the main scanning direction X, but the number and arrangement of sensors are limited to this. It is not a thing. For example, as shown in FIG. 17, both ends of the scanning path of the scanning light beam may be guided to the horizontal synchronization sensors 60A and 60B by the folding mirrors 69a and 69b. In this apparatus, signals are output from the horizontal synchronization sensors 60A and 60B at the timing when the scanning light beams are received by the horizontal synchronization sensors 60A and 60B and pass the sensor position (amplitude angle θs). Therefore, the latent image forming operation may be controlled based on the output signals of the sensors 60A and 60B. In addition, since detection signals can be obtained on both sides in the main scanning direction X, latent image formation is performed based on detection signals output from a sensor (detection unit) disposed upstream in the scanning direction of the latent image forming light beam. The operation may be controlled. Further, as shown in FIG. 18, the scanning light beam may be detected by one horizontal synchronization sensor 60C and folding mirrors 69c to 69e.

  In the above embodiment, the present invention is applied to an image forming apparatus that temporarily forms a color image on an intermediate transfer medium such as an intermediate transfer belt and then transfers the color image to the sheet S. The present invention is also applicable to an apparatus that forms a color image by directly superimposing toner images on a sheet. In this case, the sheet corresponds to the “transfer medium” of the present invention.

  In the above embodiment, the vibrating deflection mirror surface 651 is formed by using a micromachining technique. However, the method of manufacturing the deflection mirror surface is not limited to this, and the vibrating deflection mirror surface is used. The present invention can be applied to all image forming apparatuses that deflect a light beam and scan the light beam on a latent image carrier.

1 is a diagram showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus in FIG. 1. FIG. 2 is a main scanning sectional view showing a configuration of an exposure unit in the image forming apparatus of FIG. The figure which shows the scanning area | region of the light beam in the exposure unit of FIG. FIG. 2 is a diagram showing a signal processing block in the image forming apparatus of FIG. 1. FIG. 2 is a diagram showing a line latent image formed by the image forming apparatus of FIG. 1. 6 is a flowchart illustrating an operation of the image forming apparatus according to the first embodiment. The schematic diagram for demonstrating the skew information memorize | stored in FRAM. The figure which shows the latent image formed by the latent image formation operation | movement of 1st Embodiment. The flowchart which shows 2nd Embodiment of this invention. The flowchart which shows 3rd Embodiment of this invention. The flowchart which shows 4th Embodiment of this invention. FIG. 9 is a diagram illustrating an image forming apparatus according to a fifth embodiment of the invention. The flowchart which shows 5th Embodiment of this invention. The figure for demonstrating 6th Embodiment of the image forming apparatus concerning this invention. The figure which shows the line latent image formed with the apparatus concerning 6th Embodiment. FIG. 6 is a diagram showing another embodiment of the image forming apparatus according to the present invention. FIG. 5 is a diagram showing another embodiment of the image forming apparatus according to the present invention.

Explanation of symbols

  2, 2Y, 2M, 2C, 2K ... photosensitive member (latent image carrier), 6, 6Y, 6M, 6C, 6K ... exposure unit (latent image forming unit), 60, 60A to 60C ... horizontal synchronization sensor (detector) 62, 62Y, 62M, 62C, 62K ... laser light source, 71 ... intermediate transfer belt (transfer medium), 78 ... color shift sensor (information detection unit), 106 ... ROM (storage unit), 108 ... FRAM (storage unit) 112 ... I / F (input section), 651 ... deflection mirror surface, DT1, DT2, DT (n-1), DTn ... tone data (image information), IR ... effective image area, Ly, Lm, Lc , Lk ... scanning light beam, LIy, LIm, LIc, LIk, LI (+ X), LI (-X) ... line latent image, MT ... drive motor (drive means), SL1, SL2 ... scanning light beam, X ... Main scanning direction Y: Sub scanning direction

Claims (8)

A latent image carrier;
A latent image forming unit that forms a latent image on the latent image carrier by irradiating a light beam from a light source through a vibrating deflection surface;
Based on the information related to the position where the latent image is formed on the latent image carrier, the scanning direction of the light beam is either the first direction of the main scanning direction or the second direction which is opposite to the first direction. A direction control unit that is selectively set to
The latent image forming unit adjusts a latent image forming position on the latent image carrier in a scanning direction set by the direction control unit . The image forming apparatus according to claim 1, wherein the setting in the direction control unit is performed by controlling a light emission timing of a light source of the latent image forming unit. Information related to the forming position of the latent image to the latent image bearing member, an image forming apparatus according to claim 1, wherein the data indicating the position relationship between the latent image bearing member and the latent image forming unit. An input unit for receiving input of information related to a position where a latent image is formed on the latent image carrier;
A storage unit that stores information related to a latent image formation position on the latent image carrier input via the input unit;
The image forming apparatus according to claim 1, wherein the setting in the direction control unit is performed based on the information stored in the storage unit. The image forming apparatus according to claim 4, wherein an adjustment image for adjusting a formation position of the latent image is formed, and the information can be visually determined by transferring the adjustment image to a recording medium . A plurality of image forming means including the latent image carrier and the latent image forming unit, and a color image is formed using an image formed by the image forming means;
Information related to the formation position of the latent image on the latent image carrier is set in the plurality of image forming units, and the setting in the direction control unit is set to the latent image carrier of the plurality of image forming units. The image forming apparatus according to claim 1 , wherein the image forming apparatus is performed based on information relating to a formation position of the latent image . An image forming method for forming a latent image by irradiating a latent image carrier with a light beam,
An information acquisition step of acquiring information related to the formation position of the latent image on the latent image carrier;
A direction setting step of selectively setting the scanning direction of the light beam based on the information obtained by the information acquisition step to a first direction of a main scanning direction or a second direction opposite to the first direction;
An image forming step of developing the latent image and forming a toner image while adjusting the formation position of the latent image in the scanning direction set in the direction setting step by the vibrating deflection surface;
An image forming method comprising:   Storage means for storing image information constituting one line image data;
  Direction setting means for setting the order in which the image information stored in the storage means is read and the light source is controlled based on the image information based on information relating to the formation position of the latent image on the latent image carrier;
A data control device comprising: