JP2006035553A5 - - Google Patents

Description

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

In the present invention, a latent image is formed on a latent image carrier by irradiating a light beam in the main scanning direction, and then a toner image formed by developing the latent image is transferred to a recording medium to execute printing. The present invention relates to an image forming apparatus and method. The present invention also relates to a data control apparatus suitable for the image forming apparatus and method.

  This type of image forming apparatus is configured to be able to print in various modes in order to enhance the versatility of the apparatus and to increase the functionality. For example, the apparatus described in Patent Document 1 is configured to be able to print at two different resolutions. In this apparatus, a polygon mirror is provided for scanning the light beam, and the polygon mirror is rotationally driven by a mirror drive motor. Further, a mirror drive control circuit is electrically connected to the mirror drive motor, and the drive signal applied to the mirror drive motor is switched between low resolution and high resolution. For this reason, when printing at low resolution, a low resolution drive signal is applied to the mirror drive motor, and the polygon mirror rotates at a relatively low speed. On the other hand, when printing at high resolution, a high resolution drive signal is applied to the mirror drive motor, and the polygon mirror rotates at a relatively high speed. In this way, it is possible to print in two types of printing modes, high resolution printing and low resolution printing, by switching the rotation speed of the polygon mirror.

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

  By the way, in the above-described conventional apparatus, the printing mode (resolution) is switched by changing the rotational speed of the polygon mirror. For this reason, when printing on one or more recording media in a predetermined printing mode and then printing on the next recording medium in another printing mode, the rotational speed of the polygon mirror is stabilized. The next printing cannot be performed. Therefore, it is difficult to switch the printing mode quickly.

  The present invention has been made in view of the above problems, and after a latent image is formed by scanning a light beam on a latent image carrier, a toner image formed by developing the latent image is transferred to a recording medium. The first object of the present invention is to provide a technique capable of quickly switching the printing mode in an image forming apparatus that executes printing.

  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. A reciprocating scanning mode in which a light beam is reciprocated in the main scanning direction based on information relating to a latent image forming unit to be formed and a printing mode, and a light beam in a first direction in the main scanning direction or a direction opposite to the first direction. And a direction controller that selectively sets a one-way scanning mode in which one-way scanning is performed in any one of the second directions .

Further, in order to achieve the first object , the image forming method according to the present invention obtains the light beam based on an information acquisition step for acquiring information related to a printing mode, and information obtained by the information acquisition step. A reciprocating scanning mode in which reciprocating scanning is performed in the main scanning direction, and a unidirectional scanning mode in which the light beam is unidirectionally scanned in either the first direction of the main scanning direction or the second direction opposite to the first direction. And a scanning mode determining step that is selectively set, and a latent image is formed in the scanning direction determined in the scanning mode determining step by the light beam by the vibrating deflecting surface, and the latent image is developed to form a toner image. And an image forming process .

In the invention (image forming apparatus and method) thus configured, the light beam from the light source is deflected by the vibrating deflection surface, and the light beam can be reciprocated in the main scanning direction. For example, as shown in FIG. 6, the line latent image LI (+ X) is formed by the light beam scanned in the first direction of the main scanning direction, while being scanned in the second direction opposite to the first direction. A line latent image LI (-X) is formed by the light beam. Therefore, in the mode in which the light beam used for forming the latent image is reciprocated in the first direction and the second direction (reciprocating scan mode), the line latent images LI (+ X) and LI (−X) are alternately arranged in the sub-scanning direction. It is formed. On the other hand, in the mode (one-way scanning mode) in which the scanning direction of the light beam used for forming the latent image is narrowed down to the first direction or the second direction while vibrating the deflection mirror surface (one-way scanning mode), the line latent image LI ( Only one of + X) and LI (-X) is formed in the sub-scanning direction. Therefore, the printing results in these two scanning modes are different from each other. Therefore, in the present invention, the printing mode is switched by selectively setting the reciprocating scanning mode and the unidirectional scanning mode based on the information related to the printing mode. Thus, the printing mode can be changed by simply switching the scanning mode of the latent image forming light beam without changing the vibration operation of the deflecting surface . Therefore, the printing mode can be switched quickly.

  Further, in order to switch the scanning mode without changing the vibration operation of the deflecting mirror surface, for example, the direction control unit can control the light emission timing of the light source of the latent image forming unit to set the scanning mode. .

Here, “information related to printing mode” is used to select a specific printing mode from a plurality of printing modes prepared in advance in order to satisfy the versatility and high functionality of the apparatus as described above. Means necessary information. Combinations of printing modes prepared in advance include (1) high resolution printing and low resolution printing, (2) normal toner amount printing and toner save printing in which printing is performed using a normal toner amount, and (3) a predetermined value. Thin paper printing on a recording medium with the following thickness and thick paper printing on a recording medium with a thickness exceeding a predetermined value. (4) Normal quality printing and main printing that allow density difference in the main scanning direction. For example, high-quality printing is performed while printing while suppressing a density difference in the scanning direction. Therefore, in order to cope with these, the following configuration may be adopted.

(1) High-resolution printing and low-resolution printing Based on the information, the direction control unit sets the reciprocating scanning mode when executing high-resolution printing, while setting the unidirectional scanning mode when executing low-resolution printing. Can be configured to set. Here, “information” is resolution information indicating whether an image to be printed has a high resolution or a low resolution.

(2) Normal toner amount printing and toner save printing Based on the information, the direction control unit sets the reciprocating scanning mode when executing normal printing, while switching to the unidirectional scanning mode when executing toner saving printing. Can be configured to set. Here, “information” is toner amount information used when printing is performed.

(3) Thin paper printing and thick paper printing Based on the information, the direction control unit should set the reciprocating scanning mode when executing thin paper printing, and set the unidirectional scanning mode when executing thick paper printing. Can be configured. Here, “information” is thickness information indicating the thickness of the recording medium to be printed.

(4) Normal quality printing and high quality printing
When the light beam is scanned on the latent image carrier in the reciprocating scanning mode, as will be described in detail later, depending on the type of image, there are cases in which light and shade of the image occurs on the forward path side and the backward path side in the main scanning direction. That is, since a density difference is generated in the main scanning direction, it is difficult to execute high-quality printing. On the other hand, when the light beam is scanned on the latent image carrier in the unidirectional scanning mode, an image can be formed with a uniform density regardless of the type of image, and high-quality printing is possible . Therefore, the direction control unit may be configured to set the reciprocating scanning mode when executing normal quality printing based on the information, and set the unidirectional scanning mode when executing high quality printing. Good. Note that the “information” here is an image of a quality that can allow a density difference in the main scanning direction of the image to be printed, or a high quality image that cannot allow such a density difference. This is image quality information indicating whether the image is an image.

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 light beam is shifted in the main scanning direction in the second scanning region wider than the first scanning region which is the latent image forming region. While being scanned and provided with a synchronization detection unit for detecting the scanning light beam, 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 related to the printing mode .

In the invention configured as described above, the image information stored in the storage unit is read, and the order of controlling the light source based on the image information is set based on the information related to the printing mode. That is, the light emission timing of the light source of the latent image forming unit is controlled by the data control device, and the scanning mode is selectively set to the reciprocating scanning mode or the unidirectional scanning mode. For this reason, it is possible to change the printing mode simply by switching the scanning mode of the latent image forming light beam without changing the vibration operation of the deflection surface, and as a result, the printing mode can be switched quickly. .

<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 print an image corresponding to the print command on a sheet (recording medium) 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. In addition, 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 gradation characteristic that detects a gradation 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 why the two types of line buffers 116A and 116B are provided in this manner is to cope with the difference in the scanning mode of the latent image forming light beam depending on the printing mode, 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. As a result, a line-shaped latent image extending in the main scanning direction X is formed on the effective image area IR of the photosensitive member 2 by scanning the light beam in parallel with the main scanning direction X. In this embodiment, the scanning region (the “second scanning region” of the present invention) SR2 that can be scanned by the deflector 65 is used for scanning the light beam on the effective image region IR as shown in FIG. The scanning area (the “first scanning area” of the present invention) 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. For this reason, the light beam for forming a latent image (latent image forming light beam) can be made different for each printing mode or for each line as follows. More specifically, in this embodiment, information about the resolution (resolution information) included in the print command is temporarily stored in the RAM 107 as “information related to the printing mode” of the present invention. When the high resolution printing is instructed, the light beam SL1 that scans the first scanning region SR1 in the (+ X) direction is guided to the effective image region IR as a latent image forming light beam, and is transferred to the effective image region IR. An operation for forming a latent image and a light beam SL2 for scanning the first scanning region SR1 in the (−X) direction as a latent image forming light beam are guided to the effective image region IR to form a latent image in the effective image region IR. A latent image is formed by executing a so-called reciprocating scanning mode that alternately repeats the above operation. On the other hand, when low resolution printing is instructed, a latent image is formed by executing a so-called unidirectional scanning mode in which only the latent image forming light beam SL1 is repeated. Thus, in this embodiment, the scanning mode of the latent image forming light beam is switched between high resolution printing and low resolution printing based on the resolution information. 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 view showing a latent image formed by the latent image forming operation of the present embodiment. In FIG. 8 (and FIGS. 10 , 12 , 15 and 17 described later), the alternate long and short dash line indicates a virtual line indicating the trajectory of the scanning line, and the thick arrow indicates the scanning light beam for forming the latent image. Yes.

  When a print command 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, the resolution information included in the print command is acquired as “information related to the printing mode” of the present invention (information acquisition step). Based on the resolution information, it is determined whether the print command requests high resolution printing or low resolution printing (step S12).

  If “YES” is determined in step S12, that is, if it is determined that high resolution printing is performed, steps S13 to S15 are executed to form an image with high resolution, and the image is transferred to the sheet S which is the “recording medium” of the present invention. To end the printing process. First, in step S13, a reciprocating scanning mode is set (scanning mode determination step). Next, a direction switching signal corresponding to the scanning mode determined as described above is given to the direction switching unit 116C of the main controller 11 (step S14). On the other hand, upon receiving these instructions, the direction switching unit 116C alternately switches the timing and order of reading out the gradation data from the line buffer for each line. Thereby, a high-resolution latent image is formed as follows. That is, as shown in the upper part of FIG. 8, the light beam SL1 that scans the first scanning region SR1 in the (+ X) direction is guided to the effective image region IR as a latent image forming light beam, and is latent in the effective image region IR. The operation of forming an image and the light beam SL2 that scans the first scanning region SR1 in the (−X) direction as a latent image forming light beam is guided to the effective image region IR to form a latent image in the effective image region IR. The operation is repeated alternately (step S15). Thus, a so-called reciprocating scanning mode is executed, and a latent image is formed with high resolution. The latent image formed in this way 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. Is transferred to the sheet S, and high-resolution printing ends.

  On the other hand, if “NO” is determined in step S12, that is, if it is determined that low resolution printing is performed, steps S16 to S18 are executed to form an image with low resolution, and then transferred to the sheet S to finish the printing process. To do. First, in step S16, a unidirectional scanning mode is set (scanning mode determination step). Next, a direction switching signal corresponding to the scanning mode determined as described above is given to the direction switching unit 116C of the main controller 11 (step S17). On the other hand, the direction switching unit 116C that has received these instructions forms a latent image line by line by fixing the read timing and order of the gradation data from the line buffer. That is, data is read out from the forward line buffer 116A at an appropriate timing and forward direction (that is, the order of the gradation data DT1, DT2,... DTn) and scanned in the first direction (+ X) while being optically modulated based on each gradation data. Only the latent image forming light beam SL1 is scanned on the photosensitive member 2 to form a latent image (step S18). In this way, a so-called unidirectional scanning mode is executed, and a latent image is formed at a lower resolution than that of high-resolution printing. The latent image formed in this way is developed with toner to form a four-color toner image as in high-resolution printing, and is superimposed on the intermediate transfer belt 71 to form a color image. The color image is transferred to the sheet S, and the low resolution printing ends.

  As described above, according to the first embodiment, the print resolution is switched by selectively switching between the reciprocating scan mode (steps S13 to S15) and the unidirectional scan mode (steps S16 to S18) based on the resolution information. Running. As described above, high resolution printing or low resolution printing can be selectively executed by simply switching the scanning mode of the latent image forming light beam without changing the vibration operation of the deflecting mirror surface 651. Therefore, it is possible to quickly change the resolution.

Second Embodiment
Incidentally, toner save printing may be set in order to reduce toner consumption. This toner save printing omits the formation of some dots of a normal print image printed during normal printing. For example, dot formation may be omitted in units of one line. For example, the latent image formation for normal printing is executed in the reciprocating scanning mode, whereas the latent image formation for toner saving printing is executed in the one-way scanning mode, thereby switching between normal printing and toner saving printing. It becomes possible. Hereinafter, the operation of the apparatus for switching between normal printing and toner save printing will be described in detail with reference to FIGS. 9 and 10. Incidentally, omitted for basic configuration of the device according to the second embodiment (Embodiment shaped condition after and) is the same as the first embodiment, the description of those same and the corresponding reference numerals.

  FIG. 9 is a flowchart showing the operation of the image forming apparatus in the second embodiment. FIG. 10 is a view showing a latent image formed by the latent image forming operation of the present embodiment. In the second embodiment, when a print command 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. 9, and a color image is generated based on each latent image. It is formed. That is, in step S21, the used toner amount information included in the print command is acquired as “information related to the printing mode” of the present invention (information acquisition step). Whether the print command is a normal print that prints an image using a predetermined toner amount based on the used toner amount information or a toner save print that prints with a toner amount smaller than the toner amount at the time of normal printing Is determined (step S22).

  If “normal printing” is determined in step S22, steps S23 to S25 are executed to form an image by normal printing, and the image is transferred to the sheet S as the “recording medium” of the present invention, and the printing process is terminated. Note that these steps S23 to S25 are the same as the high-resolution printing of the first embodiment, and thus description thereof is omitted.

  On the other hand, if “toner save printing” is determined in step S22, steps S26 to S28 are executed to form an image in which dot formation is omitted at intervals of one line from the image formed by normal printing, and then the sheet S is formed. Transfer and finish the printing process. First, in step S26, a unidirectional scanning mode is set (scanning mode determination step). Next, when the first direction (+ X) is set as the scanning direction of the latent image forming light beam, the direction switching unit 116C receives an appropriate timing and forward direction (ie, gradation data) from the forward line buffer 116A. DT1, DT2,... DTn), and the latent image forming light beam SL1 scanned in the first direction (+ X) while being optically modulated based on each gradation data is scanned on the photosensitive member 2 to form a line latent image. LI (+ X) is formed (step S28). On the other hand, when the second direction (−X) is set as the scanning direction of the latent image forming light beam, the direction switching unit 116C does not read out the gradation data from the backward line buffer 116B, and does not read the gradation data. Scanning of the body 2 with the latent image forming light beam SL2 is prohibited, and no latent image is formed. That is, a latent image consisting only of the line latent image LI (+ X) is formed by irradiating the photosensitive member 2 in the first direction (+ X). The latent image formed in this manner is developed with toner to form a four-color toner image, and is superimposed on the intermediate transfer belt 71 to form a color image, as in normal printing. The color image is transferred to the sheet S. The image thus obtained becomes a toner save image in which dot formation is omitted in units of one line.

  As described above, according to the second embodiment, normal printing is performed by selectively switching between the reciprocating scanning mode (steps S23 to S25) and the unidirectional scanning mode (steps S26 to S28) based on the used toner amount information. Toner save printing is being switched. In this manner, normal printing or toner save printing can be selectively executed by simply switching the scanning mode of the latent image forming light beam without changing the vibration operation of the deflecting mirror surface 651. Therefore, it is possible to quickly switch from normal printing to toner save printing and vice versa.

<Third Embodiment>
Conventionally, in an image forming apparatus, there are cases where two printing modes (thin paper printing and thick paper printing) are switched according to the thickness of a recording medium (sheet S). This thin paper printing is for printing on a recording medium such as plain paper having a thickness of a predetermined value or less. On the other hand, the cardboard printing is for printing on a recording medium such as cardboard thicker than a predetermined value. The reason for switching the printing mode in this way is that the heat capacity of the sheet S (thick paper), which is a recording medium, is larger than that of plain paper in cardboard printing. The toner is sufficiently fused by passing through the fixing unit 9. Therefore, both the thin paper printing and the thick paper printing can be appropriately performed by executing the scanning mode suitable for each of the thin paper printing and the thick paper printing. Hereinafter, the operation of the apparatus for switching between thin paper printing and thick paper printing will be described in detail with reference to FIGS. 11 and 12.

  FIG. 11 is a flowchart showing the operation of the image forming apparatus according to the third embodiment. FIG. 12 is a view showing a latent image formed by the latent image forming operation of the present embodiment. In the third embodiment, when a print command 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. 11, and a color image is generated based on each latent image. It is formed. That is, in step S31, the sheet thickness information included in the print command is acquired as “information related to the printing mode” of the present invention (information acquisition step). Based on the sheet thickness information, it is determined whether the print command is thin paper printing or thick paper printing (step S32).

  If “thin paper printing” is determined in step S 32, steps S 33 to S 35 are executed to form a latent image in the reciprocating scanning mode, and the toner image formed by developing the latent image is transferred to the intermediate transfer belt 71. After forming a color image by superimposing, it is transferred to a sheet S which is a “recording medium” of the present invention, and further fixed, and the printing process is completed. Note that these steps S33 to S35 are the same as the high-resolution printing of the first embodiment, and a description thereof will be omitted.

  On the other hand, if “thick paper printing” is determined in step S32, steps S36 to S38 are executed to set the sheet conveyance speed to half the speed V during thin paper printing, and an image is formed in the unidirectional scanning mode. Thereafter, the image is transferred to the sheet S, further fixed, and the printing process is completed. First, in step S36, a unidirectional scanning mode is set (scanning mode determination step). Next, when the first direction (+ X) is set as the scanning direction of the latent image forming light beam, the direction switching unit 116C receives an appropriate timing and forward direction (ie, gradation data) from the forward line buffer 116A. DT1, DT2,... DTn), and the latent image forming light beam SL1 scanned in the first direction (+ X) while being optically modulated based on each gradation data is scanned on the photosensitive member 2 to form a line latent image. LI (+ X) is formed (step S38). On the other hand, when the second direction (−X) is set as the scanning direction of the latent image forming light beam, the direction switching unit 116C does not read out the gradation data from the backward line buffer 116B, and does not read the gradation data. Scanning of the body 2 with the latent image forming light beam SL2 is prohibited, and no latent image is formed. That is, a latent image consisting only of the line latent image LI (+ X) is formed by irradiating the photosensitive member 2 in the first direction (+ X). The latent image formed in this manner is developed with toner to form a four-color toner image, and is superimposed on the intermediate transfer belt 71 to form a color image, as in normal printing. The color image is transferred to the sheet S.

  As described above, according to the third embodiment, thin paper printing and cardboard are selectively performed by selectively switching between the reciprocating scanning mode (steps S23 to S25) and the unidirectional scanning mode (steps S26 to S28) based on the sheet thickness information. Printing switching is being executed. In this way, thin paper printing or thick paper printing can be selectively executed by simply switching the scanning mode of the latent image forming light beam without changing the vibration operation of the deflecting mirror surface 651. Accordingly, it is possible to quickly switch from thin paper printing to thick paper printing or vice versa.

<Fourth embodiment>
By the way, in the reciprocating scanning mode of the image forming apparatus, a two-dimensional latent image is formed by reciprocating the light beam in the main scanning direction X while rotating the photosensitive member 2 in the sub-scanning direction Y. For this reason, depending on the type of image, light and shade of the image may occur on the forward side and the backward side in the main scanning direction X. For example, as shown in FIG. 13, consider the case of forming a repeating pattern of 2 lines ON and 2 lines OFF.

In this apparatus, the forward path and backward path, after forming a latent image of the two lines by scanning the scanning light beam, only two lines keep off the laser source 62. As a result, a latent image of 2 lines ON and 2 lines OFF is formed. Then, a desired repetitive pattern (two-dimensional latent image) is formed by repeating this latent image forming operation. Here, the problem is the density difference in the main scanning direction X. That is, the two-dimensional latent image is formed by reciprocally scanning the scanning light beam SL in the main scanning direction X while rotating the photosensitive member 2 in the sub-scanning direction Y substantially orthogonal to the main scanning direction X. The latent image areas are different between the (+ X) direction side and the (−X) direction side, and a difference in image density occurs in the main scanning direction X. In the case of printing a normal text image, the density difference is not a special problem and is usually printed as it is (normal quality printing). Therefore, when priority is given to the resolution and speed of printing, it is desirable to adopt the reciprocating scanning mode in normal quality printing.

  On the other hand, depending on the type of image, even such a density difference may cause a problem (high quality printing). A typical example of this high-quality printing is a photographic image. That is, the demand for a photographic image is relatively high, and even a slight density difference generated on both sides (+ X) and (−X) of the image results in different impressions and colors of the entire photo. In order to solve this problem, an image may be formed in the unidirectional scanning mode, and the unidirectional scanning mode can be said to be a scanning mode suitable for high-quality printing. Therefore, in the fourth embodiment, both normal quality printing and high quality printing are appropriately performed by executing scan modes suitable for normal quality printing and high quality printing. The operation of the apparatus for switching between thin paper printing and thick paper printing will be described in detail below with reference to FIGS.

FIG. 13 is a diagram showing a latent image when a specific pattern is formed in the reciprocating scanning mode. FIG. 14 is a flowchart showing the operation of the image forming apparatus according to the fourth embodiment. FIG. 15 is a diagram showing a latent image formed by the latent image forming operation of the present embodiment. In the fourth embodiment, when a print command 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. 14, and a color image is generated based on each latent image. It is formed. That is, in step S41, the image quality information included in the print command is acquired as “information related to the printing mode” of the present invention (information acquisition step). Then, based on the image quality information, it is determined whether the print command is normal quality printing or high quality printing (step S42). Here, for the determination in step S42, information indicating whether the image to be printed is normal quality or high quality may be included in the print command. The determination in step S42 may be performed according to the type of image. For example, normal quality printing may be selected for text images and graphic images, while high quality printing may be selected for photographic images.

  If “normal quality” is determined in step S42, steps S43 to S45 are executed to form a latent image in the reciprocating scanning mode, and the toner image formed by developing the latent image is transferred to the intermediate transfer belt 71. After forming a color image by superimposing, it is transferred to a sheet S which is a “recording medium” of the present invention, and further fixed, and the printing process is completed. Since these steps S43 to S45 are the same operation as the high resolution printing of the first embodiment, the description thereof is omitted.

  On the other hand, if “high quality” is determined in step S42, steps S46 to S48 are executed to form an image in the unidirectional scanning mode, and then transferred to the sheet S, further fixed, and the printing process is terminated. First, in step S46, a unidirectional scanning mode is set (scanning mode determination step). Next, when the first direction (+ X) is set as the scanning direction of the latent image forming light beam, the direction switching unit 116C receives an appropriate timing and forward direction (ie, gradation data) from the forward line buffer 116A. DT1, DT2,... DTn), and the latent image forming light beam SL1 scanned in the first direction (+ X) while being optically modulated based on each gradation data is scanned on the photosensitive member 2 to form a line latent image. LI (+ X) is formed (step S48). On the other hand, when the second direction (−X) is set as the scanning direction of the latent image forming light beam, the direction switching unit 116C does not read out the gradation data from the backward line buffer 116B, and does not read the gradation data. Scanning of the body 2 with the latent image forming light beam SL2 is prohibited, and no latent image is formed. That is, a latent image consisting only of the line latent image LI (+ X) is formed by irradiating the photosensitive member 2 in the first direction (+ X). The latent image formed in this manner is developed with toner to form a four-color toner image, and is superimposed on the intermediate transfer belt 71 to form a color image, as in normal printing. The color image is transferred to the sheet S.

  As described above, according to the fourth embodiment, normal quality printing is performed by selectively switching between the reciprocating scanning mode (steps S23 to S25) and the unidirectional scanning mode (steps S26 to S28) based on the image quality information. High quality printing is being switched. As described above, normal quality printing or high quality printing can be selectively executed by simply switching the scanning mode of the latent image forming light beam without changing the vibration operation of the deflecting mirror surface 651. Therefore, it is possible to quickly switch from normal quality printing to high quality printing and vice versa.

  In the fourth embodiment, as in the case of thick paper printing in the third embodiment, the sheet conveyance speed may be set to half of the speed V during normal quality printing. The resolution can be increased and a higher quality image can be obtained.

<Fifth Embodiment>
FIG. 16 is a view for explaining a fifth embodiment of the image forming apparatus according to the present invention. FIG. 17 is a diagram showing a line latent image formed by the image forming apparatus according to the fifth embodiment. For example, as shown in FIG. 16, an image to be printed by the image forming apparatus may include a plurality of types such as a line drawing, a graphic image, and a photographic image. A graphic image GI, a line drawing LM such as text, and photographs PT1 and PT2 are mixed and printed on the sheet S shown in FIG. Here, when the graphic image GI and the line drawing LM are compared with the photographs PT1 and PT2, the required image quality may differ as described above. Therefore, it is desirable to perform printing in a scanning mode corresponding to each image quality even during execution of printing for one sheet S. Therefore, in the fifth embodiment, the scanning mode is switched during printing of one sheet.

  FIG. 16 shows a graphic area AR1 where the graphic image GI is formed, a line drawing area AR2 where a line drawing LM such as text is formed, and two photographic areas AR3 and AR4. Therefore, in the latent image forming operation corresponding to the areas AR1 and AR2, latent image formation is performed in the reciprocating scanning mode as shown in FIGS. 17A and 17B, while when entering the area AR3, the scanning mode is changed to halfway. The unidirectional scanning mode is continued until the latent image forming operation corresponding to the final area AR4 is completed. Thereby, a latent image can be formed in a scanning mode suitable for each region.

  In this embodiment, the photograph PT1 is arranged on the right side (−X direction side) in the photograph area AR3. Therefore, in order to obtain a higher quality image, the latent image forming light beam SL1 scanned in the (+ X) direction can be used to form the photograph PT1 using the light beam in the initial scanning stage. . In addition, it is possible to form the photo PT1 more satisfactorily by arranging the writing positions. On the other hand, in the photo area AR4, the photo PT2 is arranged on the left side (+ X direction side). Therefore, it is desirable to perform the reverse operation to that of the photographic area AR3.

  As described above, according to the fifth embodiment, normal-quality printing or high-quality printing is selected simply by switching the scanning mode of the light beam for forming a latent image without changing the vibration operation of the deflecting mirror surface 651. Therefore, the scanning mode can be switched even during printing on one sheet S. It is possible to respond flexibly and with high quality to a special printing request of printing different quality images on one sheet S. In the fifth embodiment, the case where images having different print qualities are printed on one sheet S has been described. However, when images having different resolutions and used toner amounts are printed on one sheet S, Needless to say, the present invention can also be applied.

  <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. 18, 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. 19, the scanning light beam may be detected by one horizontal synchronization sensor 60C and folding mirrors 69c to 69e.

  In the first to fourth embodiments, only the light beam SL1 scanned in the (+ X) direction is used as the latent image forming light beam in the unidirectional scanning mode. However, the light beam SL2 scanned in the (−X) direction is used. May be used. In short, the latent image forming light beam may be configured to be unidirectionally scanned in the first direction (+ X) or the second direction (−X) of the main scanning direction X.

  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 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 so-called image forming apparatuses in which a light beam is deflected to scan the 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 figure which shows the latent image formed by the latent image formation operation | movement of 1st Embodiment. 10 is a flowchart illustrating an operation of the image forming apparatus according to the second embodiment. The figure which shows the latent image formed by the latent image formation operation | movement of 2nd Embodiment. 10 is a flowchart illustrating an operation of an image forming apparatus according to a third embodiment. The figure which shows the latent image formed by the latent image formation operation | movement of 3rd Embodiment. The figure which shows the latent image at the time of forming a specific pattern in reciprocating scanning mode. 10 is a flowchart illustrating an operation of an image forming apparatus according to a fourth embodiment. The figure which shows the latent image formed by the latent image formation operation | movement of 4th Embodiment. FIG. 10 is a view for explaining a fifth embodiment of the image forming apparatus according to the invention. The figure which shows the line latent image formed with the apparatus concerning 5th 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), 651 ... deflection mirror surface, DT1, DT2, DT (n-1), DTn ... gradation data (image information) ), IR ... Effective image area, Ly, Lm, Lc, Lk ... Scanning light beam, 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 (12)

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 information related to the printing mode, a reciprocating scanning mode in which the light beam is reciprocated in the main scanning direction, and a second direction that is the first direction of the main scanning direction or the direction opposite to the first direction. An image forming apparatus comprising: a direction control unit that selectively sets a unidirectional scanning mode in which unidirectional scanning is performed in any one of the directions . The image forming apparatus according to claim 1, wherein the direction control unit controls the light emission timing of a light source of the latent image forming unit to set the scanning mode.   The image forming apparatus according to claim 1, wherein the information related to the printing mode is resolution information of a printed image.   Based on the resolution information, the direction control unit sets the reciprocating scanning mode when performing high-resolution printing for printing at a predetermined first resolution, and performs printing at a second resolution lower than the first resolution. 4. The image forming apparatus according to claim 3, wherein the image forming apparatus is set to the one-way scanning mode when executed.   The image forming apparatus according to claim 1, wherein the information relating to the printing mode is information relating to a toner amount at the time of printing.   The direction control unit sets the reciprocating scanning mode when executing printing with the first toner amount based on the information about the toner amount at the time of printing, and sets the second toner amount smaller than the first toner amount. The image forming apparatus according to claim 5, wherein when performing printing, the unidirectional scanning mode is set.   The image forming apparatus according to claim 1, wherein the information related to the printing mode is recording medium information.   The direction control unit sets the reciprocating scanning mode when printing on a recording medium having a thickness equal to or less than a predetermined value based on the recording medium information, and executes printing on a recording medium thicker than the predetermined value. 8. The image forming apparatus according to claim 7, wherein the image forming apparatus is set to the one-way scanning mode. Drive means for driving the latent image carrier at one end of the latent image carrier in the main scanning direction is provided, and the latent image forming unit emits a light beam more than the first scanning region which is a latent image forming region. It is configured to be able to scan in the main scanning direction in a wide second scanning region,
A synchronization detector that detects the light beam that moves within the second scanning region of the other end of the latent image carrier in the main scanning direction and out of the first scanning region and outputs a signal. The image forming apparatus according to claim 1, wherein a line latent image forming operation is executed based on a detection signal output from the synchronization detection unit.   The latent image forming unit is configured to scan the light beam in the main scanning direction in a second scanning region wider than the first scanning region which is a latent image forming region,
  A synchronization detection unit that detects the light beam that moves within the second scanning region on both sides in the main scanning direction and out of the first scanning region and outputs a signal; 9. The image forming apparatus according to claim 1, wherein a line latent image forming operation is executed based on the output detection signal.   An information acquisition step of acquiring information related to the printing mode;
  Based on the information obtained by the information acquisition step, a reciprocating scanning mode in which the light beam is reciprocated in the main scanning direction, and the light beam is in the first direction of the main scanning direction or in the direction opposite to the first direction. A scanning mode determination step for selectively setting the unidirectional scanning mode in which the unidirectional scanning is performed in any one of the second directions;
  An image forming step of forming a latent image in the scanning direction determined in the scanning mode determination step by the vibrating deflection surface and developing the latent image to form a toner image;
An image forming method comprising:   Storage means for storing image information constituting one line image data;
  Direction setting means for setting the order of reading the image information stored in the storage means and controlling the light source based on the image information based on information related to the printing mode;
A data control device comprising: