JP2019082697A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can reduce the number of control signals for controlling LDs as the entire apparatus even when the image forming apparatus includes a plurality of LDs corresponding to a plurality of photoreceptors.SOLUTION: A color printer 1 includes: light sources LD 101b and 101a; a polygon mirror 105 that deflects laser beams emitted from these light sources, respectively, so as to scan photoreceptors 2b and 2a; a housing that has components each of which is arranged therein such that the laser beams emitted from the LD 101b and 101a to the polygon mirror 105 become parallel to a virtual surface, and the laser beam emitted from the LD 101a is made incident on a reflection surface on an upstream side in a direction of rotation of the polygon mirror 105 with respect to a reflection surface on which the laser beam emitted from the LD 101b is made incident; laser drivers 304b and 304a that drive each light source; and a laser control unit 303 that outputs the same operation mode signals to the respective laser drivers 304b and 304a at the same timing so that each light source can be operated in the same operation mode.SELECTED DRAWING: Figure 8

Description

  According to the present invention, a plurality of light beams deflected in different directions with respect to a rotating polygon mirror scan each of a plurality of photosensitive members, and an electrostatic latent image formed on each of a plurality of photosensitive members by the plurality of light beams is The present invention relates to an electrophotographic image forming apparatus that forms an image by developing.

  In an electrophotographic image forming apparatus, a photosensitive member is exposed by a laser beam (light beam), and an electrostatic latent image formed on the photosensitive member is developed to form an image. A laser beam emitted from a light emitting element (Laser Diode: LD) is deflected by the rotating polygon mirror so that the laser beam scans on the photosensitive member. The laser beam deflected by the rotating polygon mirror is guided onto the photosensitive member by an optical member such as a lens or a mirror. Patent Document 1 describes a color image forming apparatus provided with a photosensitive member, an LD, and a rotary polygon mirror corresponding to each color. Patent Document 1 discloses an image forming apparatus that corrects the deviation between toner images formed on each photosensitive member by controlling the rotational phase of a plurality of rotating polygon mirrors.

  In an electrophotographic image forming apparatus, the timing at which the light amount control of the laser beam is performed and the emission timing of the laser beam according to the image signal are controlled by the laser driver. The laser driver is provided for each of the light emitting elements of each color. When controlling the light amount of the laser beam to a predetermined amount, the laser driver adjusts the current flowing to the LD such that the output of the light receiving element (Photodiode: PD) attached to the LD to be controlled becomes a predetermined value. This is called automatic light amount adjustment (Auto Power Control: APC), and the operation mode when this APC operation is performed is called "APC mode". The APC mode can not be performed during a period in which the laser beam scans the electrostatic latent image forming region on the photosensitive member, and therefore, is performed at a timing other than the period in which the electrostatic latent image forming region is scanned.

  Further, at the time of image formation, the laser driver supplies drive current to the LD based on the image data transmitted from the laser control unit. The operation mode of the laser driver at this time is referred to as "image mode". On the other hand, the laser driver does not supply a drive current to the LD in a period in which the laser beam is not irradiated. The operation mode of the laser driver at this time is "OFF mode". When the laser beam emitted from the light emitting element is perpendicularly incident on the reflecting surface of the rotating polygon mirror, the laser beam is emitted from the light emitting element by the structure of the LD, the optical member, and the housing to which the rotating polygon mirror is attached The laser driver is controlled to the OFF mode at the timing when the ghost image is formed. The OFF mode is a state in which the LD is not caused to emit light while storing the light quantity value in the APC mode. On the other hand, the state in which the light amount value in the APC mode is returned to "0" is referred to as "discharge mode" or "disenable mode". Also at this time, the LD does not emit light.

  Conventionally, the phase control described in Patent Document 1 controls the rotational phases of the plurality of rotary polygon mirrors in a state in which a predetermined phase difference occurs. Therefore, the image forming apparatus as disclosed in Patent Document 1 controls the laser driver such that the timing of performing the light amount control of the laser beam and the emission timing of the laser beam according to the image signal are different for each LD.

JP, 2006-297755, A

  However, the light path of a light beam emitted from a light source (LD) to the rotary polygon mirror and the light path of a light beam emitted from the other light source (LD) to the rotary polygon mirror are the rotation axes of the rotary polygon mirror. Of the four reflecting surfaces, which is substantially parallel to the imaginary plane parallel to the surface of the reflecting surface on which the light beam emitted from the light source is incident, and which is adjacent on the upstream side of the rotating polygon mirror in the rotational direction In an image forming apparatus having a configuration in which a light beam emitted from the other light source is incident, a timing at which the light amount control of the laser beam is performed and an emission timing of the laser beam according to the image signal Can not be easily controlled.

  An object of the present invention is to provide an image forming apparatus in which control of LDs is simplified in an image forming apparatus in which laser beams emitted from a plurality of LDs corresponding to a plurality of photosensitive members are deflected by a single rotating polygon mirror. With the goal.

  In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention is a rotary polygon mirror that is rotationally driven and provided with a first light source, a second light source, and four reflecting surfaces, The light beam emitted from the first light source is deflected by the reflecting surface so that the light beam scans the first photosensitive member, and the light beam emitted from the second light source is the second photosensitive member. A polygon mirror for deflecting the light beam so as to scan the light beam, an optical path of a light beam emitted from the first light source to the polygon mirror, and a light source from the second light source to the polygon mirror The light path of the light beam to be emitted is parallel to each other, and the light reflecting surface of the four light reflecting surfaces to which the light beam emitted from the first light source is incident is the upstream side of the rotating polygon mirror in the rotation direction. Emitted from the second light source to a reflective surface adjacent to The first light source is driven by an operation mode of one of a plurality of operation modes and a housing in which the first light source, the second light source, and the rotating polygon mirror are disposed such that a beam is incident. A second driving means for driving the second light source according to any one of the plurality of operation modes, an operation mode of the first light source, and the second light source And control means for outputting the same operation mode signal to the first drive means and the second drive means at the same timing so as to be the same as the operation mode.

  According to the present invention, control of the first light source and the second light source can be easily performed.

FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment. It is a figure which shows typically the structure of the laser scanning unit in FIG. 1, (a) is a top view, (b) is a front view. It is a block diagram which shows schematic structure of the control system which controls each LD contained in the conventional laser scanning unit. It is a figure for demonstrating a mode that the laser control part of FIG. 3 transmits a signal to the laser driver of each station of Y, M, C, K. FIG. It is a time chart which shows an example of the timing which the laser driver of FIG.3 (b) switches each operation mode. It is a figure which shows the control table which shows the signal pattern of the control signal (3 bit) in FIG. 4, and switching timing. It is a time chart which shows an example of the change timing of each operation mode in the case of controlling two laser drivers by one control table. It is a figure which shows an example of a structure of the control system which controls two laser drivers by one control table. It is a figure which shows typically the structure of the laser scanning unit with which the color printer concerning 2nd Embodiment was equipped, (a) shows a top view, (b) shows a front view, (c) is 4 It is a figure which shows the arrangement | positioning state of one LD. It is a time chart which shows an example of the change timing of each operation mode in the case of controlling four laser drivers. It is a figure which shows an example of a structure of the control system which controls four laser drivers by one control table. It is a figure which shows the modification of FIG. It is a figure which shows the outline of the image formation operation | movement which the color printer which concerns on the 3rd Embodiment of this invention performs. It is a time chart which shows lighting timing of each LD from the start of image formation to the end. It is a time chart which shows an example of laser luminescence control which a laser control part of a color printer concerning a 3rd embodiment of the present invention performs.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

First Embodiment
FIG. 1 is a cross-sectional view showing a schematic configuration of the image forming apparatus according to the first embodiment.

  In FIG. 1, this image forming apparatus is an electrophotographic full-color printer (hereinafter simply referred to as "color printer"). The color printer 1 has an image forming unit 200 that forms an image of a plurality of colors, that is, four colors of yellow (Y), magenta (M), cyan (C) and black (K). The image forming unit 200 includes, for each color, photosensitive drums 2a to 2d, chargers 3a to 3d, cleaners 4a to 4d, developing units 7a to 7d, and transfer blades 6a to 6d.

  The color printer 1 includes a laser scanning unit 100, an intermediate transfer belt 8, rollers 10, 11 and 21 for supporting the intermediate transfer belt 8, and a cleaner 12.

  The color printer 1 has a manual feed tray 13 containing sheets S. The sheet S on the manual feed tray 13 is fed into the apparatus by the pickup rollers 14 and 15, and registration deviation in the conveyance direction (displacement between the sheet in the sheet conveyance direction and the image on the intermediate transfer belt 8) It is corrected during conveyance of S. The color printer 1 further incorporates a sheet feeding cassette 17 in which the sheet S is stored. The sheet S in the sheet feeding cassette 17 is supplied into the conveyance path by the pickup rollers 18 and 19 and conveyed by the vertical pass roller 20, and the registration deviation in the conveyance direction is corrected by the registration roller 16 while the sheet S is conveyed. Be done.

  The color printer 1 has a secondary transfer roller 22, a fixing unit 26, a sheet discharge roller 24, and a sheet discharge tray 25.

  Next, an image forming operation performed by the color printer 1 having such a configuration will be described.

  When an image is formed by the color printer 1, first, the surfaces of the photosensitive drums 2a to 2d corresponding to the respective colors are uniformly charged to predetermined potentials by the charging devices 3a to 3d, respectively. The laser scanning unit 100 emits a laser beam (light beam) from an LD corresponding to each color based on an image signal obtained by decomposing image data input from the outside into color (Y, M, C, K). The laser beam corresponding to each color is converted into scanning light by being deflected by a polygon mirror that functions as deflection means. The laser beams deflected by the polygon mirror are guided to the respective photosensitive drums 2a to 2d by a lens, a reflection mirror, etc., and the laser beams guided to the respective photosensitive drums 2a to 2d are the surfaces of the respective photosensitive drums 2a to 2d. Expose. As a result, electrostatic latent images corresponding to the image signals of the respective colors are formed on the respective photosensitive drums 2a to 2d.

  The electrostatic latent images respectively formed on the photosensitive drums 2a to 2d are developed by the corresponding developing devices 7a to 7d. Specifically, the developing devices 7a to 7d form toner images of the respective colors by attaching toners of the respective colors to the electrostatic latent images on the corresponding photosensitive drums 2a to 2d. Then, the toner images of the respective colors on the photosensitive drums 2 a to 2 d are transferred onto the intermediate transfer belt 8, whereby a color image (toner image) is formed on the intermediate transfer belt 8. The toner and the like remaining on the photosensitive drums 2a to 2d are collected and removed from the photosensitive drums by the cleaners 4a to 4d.

  Next, the sheet S is conveyed to the secondary transfer portion at the timing when the leading end of the toner image on the intermediate transfer belt 8 rushes into the secondary transfer portion between the rotating roller 21 and the secondary transfer roller 22. Ru. The toner image on the intermediate transfer belt 8 is secondarily transferred collectively on the sheet S conveyed to the secondary transfer portion by the secondary transfer roller 22.

  The sheet S on which the toner image has been transferred is conveyed to the fixing unit 26, and the fixing unit 26 heats and presses the toner image to thermally fix the surface of the sheet S. The sheet S on which the toner image is thermally fixed is discharged onto the sheet discharge tray 25 by the sheet discharge roller 24, and a series of image forming operations are completed. The toner and the like remaining on the intermediate transfer belt 8 are collected and removed from the intermediate transfer belt 8 by the cleaner 12.

  When an image is to be formed on both sides of the sheet S, the sheet S discharged from the fixing unit 26 is once carried into the reversing conveyance path, turned upside down, and passed through the vertical pass roller 20 again. The sheet is conveyed to the secondary transfer unit, and an image is formed on the other side in the same manner as described above.

  FIG. 2 is a view schematically showing the configuration of the laser scanning unit 100 in FIG. 1, (a) is a plan view, and (b) is a front view.

  The laser scanning unit 100 includes a housing in which each component is disposed, and includes two LDs 101a and 101b. The LD 101 b functions as a first light source in the present embodiment, and the LD 101 a functions as a second light source in the present embodiment. The laser scanning is performed so that the optical path of the laser beam emitted from the LD 101a and directed to the polygon mirror 105 described later and the optical path of the laser beam emitted from the LD 101b and directed to the same polygon mirror 105 become parallel to each other. It is disposed in the unit 100. That is, in the laser scanning unit of the present embodiment, the optical path of the laser beam 120a and the optical path of the laser beam 120b emitted toward the polygon mirror 105 respectively from the LD 101a as the first light source and the LD 101b as the second light source It is configured to be parallel to the rotation axis of the polygon mirror 105 and parallel to a virtual plane (dotted lines shown in FIGS. 2A and 2B) including the rotation axis. Here, parallel is not a mathematical exact parallel but is a concept including parallel that can be regarded as parallel in practical use, that is, substantially parallel. The polygon mirror which functions as a rotating polygon mirror will be described in detail later.

  The LD 101 a is a light source for Y image, and the LD 101 b is a light source for M image. Then, another laser scanning unit having the same configuration as that of the laser scanning unit 100 is provided to print C and K images, thereby enabling printing of all the images for Y, M, C, and K. ing.

  The laser scanning unit 100 includes LDs 101a and 101b for Y and M images, collimator lenses 102a and 102b, aperture stops 103a and 103b, and cylindrical lenses 104a and 104b. The laser scanning unit 100 also has toric lenses 107a and 107b for Y and M images, diffractive optical elements 108a and 108b, and folding mirrors 109a and 109b. The laser scanning unit 100 further includes a polygon mirror 105 which is rotationally driven and a scanner motor 106 which drives the polygon mirror 105.

  The collimator lenses 102a and 102b convert the laser beams 120a and 120b respectively emitted from the LDs 101a and 101b into parallel light beams. The aperture stops 103a and 103b limit the luminous flux of the passing laser beams 120a and 120b. The cylindrical lenses 104a and 104b have a predetermined refracting power (degree of refraction) only in the sub-scanning direction (direction corresponding to the rotation direction of the photosensitive drum), and the luminous flux of the laser beams 120a and 120b The light is imaged as an elliptical image long in the main scanning direction on the reflective surface.

  The polygon mirror 105 is rotated at a constant speed in the direction of the arrow in FIG. 2A by the scanner motor 106, and deflects the laser beam so that the laser beam incident on the reflecting surface scans the respective photosensitive drums.

  As described above, in the light source 101a and the light source 101b, the optical path of the laser beam emitted from the light source 101a and the optical path of the laser beam emitted from the light source 101b are parallel to the rotation axis of the polygon mirror 105 and the rotation The laser scanning unit 100 is disposed parallel to an imaginary plane passing through the axis. The polygon mirror 105 is square as shown in FIG. 2A and has four reflecting surfaces. The diagonal length of the polygon mirror 105 is longer than the distance between the optical path of the laser beam 120a emitted from the light source 101a and the optical path of the laser beam 120b emitted from the light source 101b. Therefore, the reflecting surface on which the laser beam 102a emitted from the light source 101a is incident is a reflecting surface adjacent to the reflecting surface on which the laser beam 120b emitted from the light source 101b is incident. Since the polygon mirror 105 is rotated clockwise as shown in FIG. 2A, the reflecting surface on which the laser beam 120a emitted from the light source 101a is incident is incident on the laser beam 120b emitted from the light source 101b. The reflection surface is located on the upstream side in the rotational direction of the polygon mirror 105 with respect to the reflection surface.

  The four reflective surfaces deflect the laser beam 120b so that the laser beam 120a emitted from the LD 101a scans the first photosensitive drum 2a, and the laser beam 120a emitted from the LD 101b passes the second photosensitive drum 2b. The laser beam 120b is deflected to scan.

  In FIG. 2A, the laser beam 120a for Y image is deflected to the left by the polygon mirror 105, and the laser beam 120b for M image is deflected to the right by the polygon mirror 105. The laser beam 121a deflected by the polygon mirror 105 is guided to the photosensitive drum 2a by the toric lens 107a, the diffractive optical element 108a, and the reflection mirror 109a. The laser beam 121b deflected by the polygon mirror is guided to the photosensitive drum 2b by the toric lens 107b, the diffractive optical element 108b, and the reflection mirror 109b.

  The toric lenses 107a and 107b are optical elements having fθ characteristics, and have different refractive indexes in the main scanning direction and the sub scanning direction. The lens surfaces of the toric lenses 107a and 107b located on the front and back sides with respect to the main scanning direction have an aspherical shape. The diffractive optical elements 108a and 108b are optical elements having fθ characteristics, and have different magnifications in the main scanning direction and the sub scanning direction.

  The laser beam 120 a moves (scans) from top to bottom in FIG. 2 by being deflected by the polygon mirror 105. On the other hand, the laser beam 120 b moves (scans) from the bottom to the top in FIG. 2 by being deflected by the polygon mirror 105.

  The laser scanning unit 100 of the present embodiment includes four polygon mirrors 105, and the laser beams 120a and 120b take parallel optical paths to be incident on the adjacent reflecting surfaces of the polygon mirror 105, so that the laser is scanned in one scanning cycle. The scanning position of the beam 102a and the scanning position of the laser beam 102b are point symmetric with respect to a predetermined point included in the imaginary plane.

  The laser beam for the M image deflected by the polygon mirror 105 is incident on a beam detector (BD) 114 disposed on the scanning path of the laser beam. The BD 114, which is a signal generation unit, outputs a signal (hereinafter referred to as "BD signal") indicating a scan timing (reference timing) based on the incident laser beam 122b. That is, the BD 114 receives the laser beam emitted from the second light source 101 b and deflected by the polygon mirror 105, and outputs a synchronization signal in response to the reception of the laser beam. A laser control unit 303 (see FIG. 4) described later switches the operation mode signal to be transmitted to the laser drivers 304 a and 304 b based on the generation timing of the synchronization signal generated by the BD 114. Therefore, in one scanning cycle of the laser beam, the emission timing of the laser beam of the light source 101b based on the image data is started a predetermined time after the timing when the BD signal is output from the BD 114. The control of the emission timing of the laser beam of the light source 101 a and the operation mode are also controlled based on the BD signal output from the BD 114.

  Hereinafter, the control system of the image forming apparatus according to the present embodiment will be described in detail in comparison with the control system of the prior art.

  FIG. 3 is a block diagram showing a schematic configuration of a control system that controls each LD included in the laser scanning unit. FIG. 3 (a) shows a configuration in the case of emitting a single laser beam using one LD for each color, and FIG. 3 (b) shows a plurality (two) using two LDs for each color The configuration in the case of emitting a laser beam of 3A and 3B are block diagrams showing schematic configurations for forming an image of one predetermined color among Y, M, C, and K, respectively. Therefore, in the apparatus for forming a color image as in the color printer 1 according to the present embodiment, four configurations of (a) or (b) of FIG. 3 are provided.

  In FIG. 3B in which two LDs are applied to each color, the laser control unit 303 transmits a control signal for switching the control mode to the laser driver 304a. Since the laser driver 304a drives the light source 101a composed of the LD1 and the LD2, the control signal is composed of 3 bits of CTL0 to CTL2. The number of control signals is determined by the number of operation modes of the laser driver 304a. The operation mode includes the APC mode of the LD1, the APC mode of the LD2, the OFF mode, the image mode, and the like. When the number of laser beams increases according to the number of LDs, the number of APC modes also increases, so the number of control signals also increases.

  The laser control unit 303 also transmits a light amount control signal for setting the light amount of the laser beam and image data 1 and 2 for drawing an image to the laser driver 304 a.

  FIG. 4 is a diagram for explaining how the laser control unit 303 in FIG. 3 transmits a signal to the laser drivers 304a to 304d of each of the Y, M, C, and K stations. In FIG. 4, only the laser control signal is described, and the light amount control signal and the image data 1 and 2 are omitted. This is because the laser control signal is subject to reduction, but the light quantity control signal and the image data 1 and 2 must be transmitted independently at each station, and this is a type of signal that can not be targeted for reduction. is there. The laser driver 304a functions as a first driving unit in the present embodiment, and the laser driver 304b functions as a second driving unit in the present embodiment.

  In FIG. 4, the laser driver 304 a and the laser control unit 303 are connected by a wire (first wire), and the laser control unit 303 transmits an operation mode signal to the laser driver 304 a through the first wire. The laser driver 304 b and the laser control unit 303 are connected by a wire (second wire), and the laser control unit 303 transmits an operation mode signal to the laser driver 304 b through the second wire. The laser driver 304 c and the laser control unit 303 are connected by a wire (third wire), and the laser control unit 303 transmits an operation mode signal to the laser driver 304 c through the third wire. The laser driver 304 d and the laser control unit 303 are connected by a wire (fourth wire), and the laser control unit 303 transmits an operation mode signal to the laser driver 304 d through the fourth wire.

  The laser drivers 304a, 304b, 304c, and 304d drive the corresponding LDs 101a, 101b, 101c, and 101d in one of a plurality of operation modes. The laser scanning unit 100 of the present embodiment includes four polygon mirrors 105, and the laser beams 120a and 120b take parallel optical paths to be incident on the adjacent reflecting surfaces of the polygon mirror 105, so that the laser is scanned in one scanning cycle. The scanning position of the beam 102a and the scanning position of the laser beam 102b are point symmetric with respect to a predetermined point included in the imaginary plane. Therefore, the periods for scanning the photosensitive drums respectively corresponding to the LD 101a, the LD 101b, the LD 101c, and the LD 101d substantially coincide with each other. Therefore, at least the period of the image mode in which the photosensitive drum is scanned in one scanning cycle can be made the same timing among the LD 101a, the LD 101b, the LD 101c, and the LD 101d. Therefore, the laser control unit 303 provided in the image forming apparatus according to the present embodiment controls the laser drivers 304a and 304b so that the operation modes of the LDs 101a, 101b, 101c and 101d at an arbitrary timing become the same based on the BD signal. , 304c and 304d, and output the same operation mode signal at the same timing.

  Since the control signals are transmitted by three signal lines in parallel per color, each control signal is described as a control signal (3 bits).

  FIG. 5 is a time chart showing an example of timing when the laser driver 304a of FIG. 3B switches each operation mode.

  In FIG. 5, first, the laser driver 304b of FIG. 4 drives the LD 101b, and immediately before the laser beam is incident on the BD 114 (timing t0), the laser driver 304a switches the LD1 to the APC mode and the BD 114 transmits the laser beam. At the detection timing (timing t1), the light amount of the LD 1 is adjusted. Here, the light amount adjustment of the LD 1 is performed based on the output of a PD (light receiving element) attached (built in) to the LD 1.

  Next, after setting the LD 1 and LD 2 to the OFF mode (timing t 2), the laser driver 304 a sets the LD 2 to the APC mode (timing t 3) and adjusts the light amount of the LD 2. The light amount adjustment of the LD 2 is performed in the same manner as the light amount adjustment of the LD 1. At the subsequent timing t4, the laser driver 304a puts the LD1 and LD2 in the OFF mode until the image formation timing t5.

  Then, the laser driver 304a sets the LD1 and LD2 to the image mode from the image formation timing t5, receives the image data 1 and 2 from the laser control unit 303, and turns on the laser of each LD1 and LD2 according to the image data 1 and 2. I do.

The switching of each mode is performed as follows based on the control signals CTL0 to CTL2 from the laser control unit 303. That is,
LD1 APC mode: CTL0 = “L”: CTL1 = “H”: CTL2 = “L”; OFF mode: CTL0 = “H”: CTL1 = “H”: CTL2 = “L”; LD2 APC mode: CTL0 = "H": CTL1 = "L": CTL2 = "L"; Image mode: CTL0 = "H": CTL1 = "H": CTL2 = "H"; Discharge mode: CTL0 = "L": CTL1 = " L ": CTL2 =" L "; Here, CTL0 to CTL2 indicate each bit of the control signal (3 bits), "L" indicates "low level", and "H" indicates "high level". Moreover, the timing which controls each mode is every predetermined time from the time (timing t1) when BD (114) detected the laser beam.

  FIG. 6 is a view showing a control table showing signal patterns of control signals (3 bits) in FIG. 4 and switching timings. The control table is determined in advance and stored, for example, in a non-volatile memory (not shown) provided in the laser control unit 303. In FIG. 6, "0" means "L" and "1" means "H".

  In FIG. 6, at 10 μs (timing t2) after the BD 114 detects the laser beam (timing t1 in FIG. 5), the APC mode (“010”) of the LD 1 is switched to the OFF mode (“011”). After 20 μs (timing t3), the laser beam is switched to the APC mode (“001”) of the LD 2 and switched to the OFF mode (“011”) 40 μs (timing t4) after the detection timing t1 of the laser beam. Then, after 80 μs (timing t5), the mode is switched to the image mode (“111”), and after 280 μs (timing t6), the mode is switched to the OFF mode (“011”). Furthermore, the laser beam is switched to the APC mode (“010”) of the LD 1 350 μs (timing t 7) after the detection timing t 1 of the laser beam. During the APC mode of the LD 1, not only the Y station but also the LD 1 of the M station emits light, the BD 114 detects the laser beam in the next image formation.

  Here, although the optical system of the laser scanning unit 100 adopts a configuration divided into two groups of left and right as shown in FIG. 2 described above, in the case of adopting this configuration, it is possible to use one control table of FIG. The laser drivers 304a and 304b for Y image and M image can be controlled in common. Therefore, in the present embodiment, the laser control unit 303 has one control table shown in FIG. 6 corresponding to both the Y and M stations and one corresponding to both the C and K stations.

  FIG. 7 is a time chart showing an example of the switching timing of each operation mode in the case where two laser drivers are controlled by one control table, corresponding to the time chart of the prior art shown in FIG. It is.

  In FIG. 7, similarly to FIG. 5, each laser driver 304 switches the LD 1 to the APC mode immediately before the laser beam is incident on the BD 114 (timing t0) and causes the BD 114 to detect the laser beam (timing t1). Adjust the light intensity. Here, the light amount adjustment of the LD 1 is performed based on the output of a PD (light receiving element) attached (built in) to the LD 1. That is, the PD receives a laser beam emitted from the LD 1 as a light source, and the laser driver 304 executes light amount control (APC) to control the light amount of the laser beam emitted by the LD 1 based on the light reception result of the PD. Do.

  Next, after setting the LD 1 and the LD 2 to the OFF mode (timing t 2), the laser driver 304 sets the LD 2 to the APC mode (timing t 3) and adjusts the light amount of the LD 2. The light amount adjustment of the LD 2 is performed in the same manner as the light amount adjustment of the LD 1. The LD1_APC mode and the LD2_APC mode are referred to as an enable mode. The enable mode is a mode in which emission of a laser beam is permitted. At the subsequent timing t4, the laser driver 304 puts the LD1 and LD2 in the OFF mode until the image formation timing t5. The OFF mode is called disable mode. The disable mode is a mode in which the emission of the laser beam is not permitted. The laser control unit 303 transmits, to the laser driver 304, either an enable signal for driving the LD1 and LD2 in the enable mode or a disable signal for driving in the disable mode as an operation mode signal.

  Then, the laser driver 304 sets the LD 1 and LD 2 to the image mode from the image formation timing t 5, receives the image data 1 and 2 from the laser control unit 303, and turns on the laser of each LD 1 and LD 2 according to the image data 1 and 2. I do. The image mode is a period in which laser beams emitted from the LD 1 and the LD 2 scan an area on the corresponding photosensitive member on which an electrostatic latent image is formed. In the image mode, the laser control unit 303 outputs an enable signal to the corresponding laser driver 304 at a timing based on the synchronization signal in order to allow each LD to emit a laser beam.

  In addition, the laser control unit 303 outputs an enable signal to the laser driver 304 at timing based on the synchronization signal even during an image mode period. Thus, the above-described light amount control is performed during a period other than the image mode. Further, the laser control unit 303 outputs a disable signal to the laser driver 304 at the timing when the light amount control ends. Each of the LD 1 and the LD 2 has the same number of light emitting points. The laser control unit 303 outputs the enable signal a plurality of times so that the light amount control is performed to each of the plurality of light emitting points in a period other than the image mode, and outputs the disable signal after each enable signal is output.

  Further, in FIG. 7, the switching timings of CTL0 to CTL2 at both the Y and M stations are the same. This is the same as switching of each operation mode performed by the laser driver 304b on the M side based on the BD signal detected on the M side, which is performed by the laser driver 304a on the Y side (see FIG. 4). It is because it can be performed at the timing. Strictly speaking, the reflecting surfaces of the polygon mirror 105 scanning each of the Y side and the M side are different at the same time, so the scanning speeds of Y and M differ due to manufacturing errors of each reflecting surface of the polygon mirror 105 . Therefore, when the Y-side write timing at the time of image formation is determined based on the BD signal detected on the M side, the image position in the main scanning direction matches on the M side but shifts on the Y side. It is displaced by one rotation cycle of the polygon mirror 105. However, slight deviation of the switching timing of each operation mode in the laser drivers 304a and 304b does not matter. This is because it is generally designed to allow some allowance for the time for the laser drivers 304a and 304b to cause the respective LDs 101a and 10b to perform the APC operation. Further, even if there is a slight error in the mode for receiving image data, that is, the switching timing to the image mode, there is no problem because the image writing timing depends on the image data. As described above, if the deviation between the timings at which the laser drivers 304a and 304b switch the respective operation modes is due to a manufacturing error of the polygon mirror 105, the deviation is not particularly problematic.

  FIG. 8 is a diagram showing an example of a configuration in which two laser drivers are controlled by one control table, and corresponds to the prior art shown in FIG.

  In FIG. 8, a laser control unit 303a and a laser driver 304a are connected by a wire for transmitting an operation mode signal, and a wire obtained by branching this wire on the way similarly serves as a wire for transmitting an operation mode signal to the laser driver 304b. It is connected.

  In the configuration of FIG. 4, the laser control unit 303 transmits a control signal (3 bits) to each of the laser drivers 304 a to 304 d. On the other hand, in the control system of FIG. 8 showing the present embodiment, the control signal (3 bits) is shared by both the Y and M stations, and is similarly shared by both the C and K stations. As a result, the total of 12 control signals required at each station of Y, M, C, and K can be reduced to six of that half.

  As described above, according to the present embodiment, the control tables of two optical systems having the same switching timing are integrated into one, and two laser drivers are controlled by one control table. To reduce the number of control signals.

Second Embodiment
In the first embodiment, one laser scanning unit 100 having the configuration shown in FIG. 2 is provided for Y and M, and for C and K, and control signals (3 bits) are provided for Y and M. Shared by both stations of C and stations of C and K respectively.

  On the other hand, in the present embodiment, as a laser scanning unit, one having a configuration in which Y, M, C, and K are combined into one optical system is employed. The configuration other than the laser scanning unit is the same as that of the color printer 1 of the first embodiment. Therefore, the hardware of the color printer according to the present embodiment is the same as the hardware of the color printer 1 of the first embodiment, and the hardware shown in FIG. 1 is adopted as it is.

  Hereinafter, the second embodiment will be described in detail focusing on differences from the first embodiment.

  FIG. 9 is a view schematically showing the configuration of a laser scanning unit 100 'provided in the color printer according to the second embodiment, wherein (a) shows a plan view and (b) shows a front view, (C) shows the arrangement of four LDs 101a to 101d. 9 (a) to 9 (c), the same components as those in FIGS. 2 (a) and 2 (b) are denoted by the same reference numerals, and the description thereof will be appropriately omitted.

  In FIG. 9A, a laser scanning unit 100 'includes a housing in which each component is disposed, and includes four LDs 101a and 101b and LDs 101c and 101d. Similar to FIG. 2 (a), two LDs are drawn in the drawing of FIG. 9 (a) as in FIG. 2 (a). However, as shown in FIG. 9C, another LD 101b is disposed immediately below the LD 101a, and similarly, the LD 101c is disposed immediately below the LD 101d. Therefore, the laser scanning unit 100 'forms electrostatic latent images corresponding to four colors of Y, M, C, and K on the photosensitive drums 2a to 2d, respectively, using a total of four LDs 101a to 101d. The LD 101 d functions as a first light source in the second embodiment, and the LD 101 a functions as a second light source in the second embodiment. The LD 101 c functions as a third light source in the second embodiment, and the LD 101 b functions as a fourth light source in the second embodiment.

  The laser beams emitted from the LDs 101a and 101b at the Y and M stations pass through the collimator lenses 102a and 102b and are converted into parallel light beams. Then, the light passes through the aperture stops 103a and 103b and is restricted. Further, the light beam passes through the cylindrical lenses 104a and 104b, and is imaged on the reflection surface of the polygon mirror 105 as an elliptical image long in the main scanning direction. The LDs 101a and 101b are installed at different positions in the height direction for Y image and M image. In the present embodiment, the laser beams 120 a and 120 b are incident on the polygon mirror 105 by taking an optical path that is oblique to the axial direction of the rotation axis of the polygon mirror 105. Therefore, the polygon mirror 105 is irradiated at substantially the same position for the Y image and the image M. The embodiment may be a laser scanning unit configured to be incident on the polygon mirror 105 by taking an optical path substantially perpendicular to the axial direction of the rotation axis of the polygon mirror 105. The polygon mirror 105 is rotated at a constant speed in the direction of the arrow in FIG. 9A by the scanner motor 106, and deflects the laser beam so that the laser beam incident on the reflecting surface scans the respective photosensitive drums. In FIG. 9A, laser beams for Y image and M image are scanned on the left side, and laser beams for C image and K image are scanned on the right side.

  First, optical systems for Y image and M image will be described.

  When the laser beams 120a and 120b from the LDs 101a and 101b enter the reflecting surface of the polygon mirror 105 at an angle of 45 °, they are reflected at 90 ° to the incident beam. The laser beams 121a and 121b reflected at 90 ° pass through the same toric lens 107a and the same diffractive optical element 108a. Then, as shown in FIG. 9B, the laser beam 121a for Y image is reflected by the folding mirror 109a, and is finally irradiated onto the photosensitive drum 2a. On the other hand, the laser beam 121b for the M image is reflected by the first turning mirror 130a, and then reflected by the second turning mirror 131a, and then irradiated onto the photosensitive drum 2b. The respective laser beams for Y image and M image scan the photosensitive drums to be irradiated as different from photosensitive drum 2a and photosensitive drum 2b, but scan approximately the same position in the main scanning direction.

  The laser beam deflected by the polygon mirror 105 also enters the BD 114. However, the laser beam 122b incident on the BD 114 is not a laser beam for Y image or M image, but one of laser beams 120c and 120d for C image or K image is deflected by the polygon mirror 105 It is. The BD 114 serving as a signal generation unit has the same configuration as the BD 114 in FIG. 2 and functions in the same manner, and outputs a BD signal based on the incident laser beam 122 b. As described later, the imaging for the Y image and the M image is generated by the BD 114 detecting the laser beams 120c and 120d for the C image or the K image (in the present embodiment, for the K image). It starts after a predetermined time from the output timing of the BD signal.

  In the present embodiment, switching of the APC mode in each of the laser drivers 304a and 304b is also performed every predetermined time within one scan based on the BD signal. When the polygon mirror 105 of four faces is adopted, as in the relationship between the laser beam for Y image and the laser beam for M image in the above-mentioned first embodiment, the scanning becomes symmetrical on the left and right. The image writing timing may be affected by the variation in the accuracy of the reflecting surface of the polygon mirror 105, so that correction is performed for each polygon mirror 105 with respect to the detection timing of the BD signal, and then drawing is started. On the other hand, the switching timing of each operation mode of each of the laser drivers 304a and 304b can be set to the same timing for the Y image and for the M image, because some errors can be tolerated.

  Next, optical systems for C image and K image will be described.

  The laser beams 120c and 120d emitted from the LDs 101c and 101d for C and K images pass through the collimator lenses 102c and 102d and are converted into parallel light beams. Then, the light passes through the aperture stops 103c and 103d and is restricted. Further, the light beam passes through the cylindrical lenses 104 c and 104 d and is imaged on the reflection surface of the polygon mirror 105 as an elliptical image long in the main scanning direction. The LDs 101 c and 101 d are installed at different positions in the height direction for the C image and the K image. The laser beams 120 c and 120 d take an optical path that is oblique to the axial direction of the rotation axis of the polygon mirror 105 and enter the polygon mirror 105. Therefore, the polygon mirror 105 is irradiated at substantially the same position for the C image and the K image. The embodiment may be a laser scanning unit configured to be incident on the polygon mirror 105 by taking an optical path substantially perpendicular to the axial direction of the rotation axis of the polygon mirror 105. The polygon mirror 105 is rotated at a constant speed in the direction of the arrow in FIG. 9A by the scanner motor 106, and deflects the laser beam so that the laser beam incident on the reflecting surface scans the respective photosensitive drums. In FIG. 9A, laser beams for Y image and M image are scanned on the left side, and laser beams for C image and K image are scanned on the right side. At this time, the position reflected by 90 ° as viewed from the LDs 101c and 101d is the center of the photosensitive drum 2d in the main scanning direction and the image center. That is, when the laser beams 120c and 120d from the LDs 101c and 101d enter the polygon mirror 105 at an angle of 45 °, they are reflected at 90 ° to the incident beam. The laser beams 121c and 121d reflected at 90 ° pass through the same toric lens 107b and the same diffractive optical element 108b. Then, as shown in FIG. 9B, the laser beam 121d for the K image is reflected by the folding mirror 109b and is finally irradiated onto the photosensitive drum 2d. On the other hand, the laser beam 121c for the C image is reflected by the first turning mirror 130b, and then reflected by the second turning mirror 131b, and then irradiated to the photosensitive drum 2c. The laser beams for the C image and the K image are scanned at substantially the same position in the main scanning direction although the photosensitive drums to be irradiated are different such as the photosensitive drum 2c and the photosensitive drum 2d.

  Since the scanning timing of the laser beam at each of the Y, M, C, and K stations is the same, the switching timing to the APC mode may be common to Y, M, C, and K.

  In the present embodiment, the optical path of the laser beam 120d and the optical path of the laser beam 120a are parallel to the rotation axis of the polygon mirror 105 and substantially parallel to a virtual plane including the rotation axis. The laser beam 120a is incident on the reflecting surface adjacent to the upstream side of the polygon mirror 105 in the rotational direction with respect to the reflecting surface of the polygon mirror 105 on which the laser beam 120d is incident. The laser beam 120c is incident on the same reflection surface as the incident reflection surface of the laser beam 120d, and the laser beam 120b is incident on the same reflection surface as the incident reflection surface of the laser beam 120a. A mirror 105 is arranged.

  FIG. 10 is a time chart showing an example of switching timing of each operation mode in the case of controlling four laser drivers.

  The switching timing of each operation mode of the time chart of FIG. 10 and the time chart of FIG. 7 described above is the same. Therefore, the description of the time chart of FIG. 10 is omitted.

  Further, in FIG. 10, since the switching timing of each operation mode is the same for all the laser drivers, the control table used for the switching control is Y, M, C, K for one control table of FIG. Shared for each laser driver. That is, four laser drivers corresponding to four LDs are controlled using one control table.

  FIG. 11 is a diagram showing an example of a configuration in which four laser drivers are controlled by one control table, and corresponds to FIG. 8 in the first embodiment described above.

  In FIG. 11, a laser control unit 303 and a laser driver 304a are connected by a wire for transmitting an operation mode signal. Further, the wiring for transmitting the operation mode signal is branched midway, and the wiring for transmitting the branched operation mode signal and the laser drivers 304 b to 304 d are connected respectively. The laser control unit 303 outputs a common control signal (3 bits) for Y, M, C, and K, and this control signal (3 bits) is distributed to the Y, M, C, and K laser driver substrates. .

  According to the present embodiment, the control tables of the four optical systems whose switching timings are the same are one, and the laser drivers corresponding to the four LDs are controlled by one control table. Can further reduce the number of control signals.

  FIG. 12 is a view showing a modification of FIG.

  In FIG. 12, Y, M, C, and K laser drivers 304a to 304d are provided on one substrate, and wiring inside the substrate distributes control signals (3 bits) in parallel to the respective laser drivers 304a to 304d. It is configured.

  Generally, an LD is mounted on a laser driver substrate, and the laser driver substrate is attached to a laser scanning unit. The laser control unit is installed together with the drive control unit of the color printer main body and the like, and is separated from the laser driver substrate. Therefore, when the laser control unit transmits a control signal, an image signal or the like to the laser driver substrate, it is necessary to connect the two with an electric wire and transmit the electric signal through the electric wire.

  However, as shown in FIG. 12, by arranging the Y, M, C, and K laser drivers 304a to 304d on a single laser driver substrate, the number of wires transmitting the control signal (3 bits) is one. It can be reduced to / 4.

Third Embodiment
Next, a third embodiment will be described.

  The color printer of the present embodiment is different from the color printer of the second embodiment described above in part of control processing executed by the laser control unit 303. The hardware configuration of the color printer according to the present embodiment is the same as the hardware configuration of the color printer according to the second embodiment.

  As in the first or second embodiment described above, when control signals (3 bits) are shared for all stations of Y and M and C and K, or Y, M, C, K, image formation At the start, each LD corresponding to the color sharing the control signal is simultaneously switched to the APC mode. Therefore, in the APC mode in the non-image area, the LD of the color sharing the control signal is simultaneously turned on. This point will be described using FIG. 10 described above. When the image is not printed, the LDs 101a to 101d do not emit light in the image mode but emit light in the APC mode of the LD1 and LD2. Therefore, to turn off the LDs 101a to 101d, the APC operation has to be stopped. The same is true for the case where the APC operation is started after the end of the image formation.

  Thus, when control signals (3 bits) are shared for all Y, M, C, and K, Y, M, C, and K are immediately after the start of image formation (timing Ts) as shown in FIG. Since each APC operation is simultaneously started, each of the LDs 101a to 101d simultaneously starts to emit light. Then, also at the end of image formation (timing Te), the timing for stopping the APC operation is the same for all of Y, M, C, and K.

  FIG. 13 is a view showing an outline of an image forming operation performed by the color printer of the present embodiment.

  In FIG. 13, when the image formation is started, the photosensitive drum 2a for Y image first starts printing, and when the printing is finished, the photosensitive drum 2d for K image is finally printed. Therefore, from the viewpoint of the lifetime of the LD, as shown in FIG. 14B, the lighting timings of the LDs 101a to 101d are delayed in the order of Y, M, C, and K at the start of image formation (sequential lighting). Similarly, at the end of the image formation, the APC operation for the Y image is stopped as soon as possible, and the APC operation for the K image is stopped immediately after the printing of the K image (the light is turned off sequentially).

  In this case, the timing for starting / terminating the APC mode is the same as the timing shown in FIG. 10, and the value of the light quantity control signal (see FIG. 3) transmitted to the respective laser drivers 304a to 304d is changed. The laser emission control as shown in 14 (b) is performed. Specifically, the laser control unit 303 sets the value of the light amount control signal to 0% before the start of image formation, and after the start of image formation, the value of the light amount control signal to a predetermined value (for example, 80% of light amount) Make it When the value of the light amount control signal is 0%, the laser drivers 304a to 304d do not cause the LDs 101a to 101d to emit light. The amount of light necessary for printing varies according to the environmental temperature and humidity, and the amount of use of the photosensitive drums 2a to 2d.

  FIG. 15 is a time chart showing an example of laser emission control performed by the laser control unit 303 of the color printer of the present embodiment.

  In FIG. 15, when image formation is started, the laser control unit 303 first changes the value of the light amount control signal for K image from 0% of light amount to 80% of light amount. Thus, the reason why the LD 101d for K image is made to emit light first is that the BD signal is detected based on the laser beam emitted from the LD 101d of K in the laser scanning unit 100 'of the color printer of this embodiment. It is.

  Thereafter, the value of the light quantity control signal for Y image is changed from the light quantity of 0% to the light quantity of 80% at a delay amount (timing Ts) equivalent to the printing delay determined by the interval between the photosensitive drums 2a to 2d in FIG. Similarly, for the M and C images, the print delay is sent (timing T2, T3) to change the value of the light control signal from 0% to 80%. At the end of the image formation, the laser control unit 303 changes the value of the light amount control signal from the light amount 80% to the light amount 0% when the printing for the Y image ends (timing T4). Similarly, immediately after the printing for each of M and C is completed (timing T5 and T6), the value of the light quantity control signal is changed from the light quantity of 80% to the light quantity of 0%. Then, finally (timing Te), the laser control unit 303 changes the value of the light quantity control signal for K from 80% of light quantity to 0% of light quantity.

  According to the present embodiment, the light emission time of the LDs 101a to 101c of Y, M, and C can be shortened by the above control, and the lifetime of each of the LDs 101a to 101c can be extended.

DESCRIPTION OF SYMBOLS 1 color printer 2a-2d Photosensitive drum 3a-3d Charger 6a-6d Transfer blade 7a-7d Development unit 8 Intermediate transfer belt 100, 100 'Laser scanning unit 101a-101d LD
102a to 102d Collimator lenses 103a to 103d Aperture stop 104a to 104d Cylindrical lens 105 Polygon mirror 106 Scanner motor 107a, 107b Toric lens 108a, 108b Diffractive optical element 109a, 109b Folding mirror 114 BD
130a, 130b First folding mirror 131a, 131b Second folding mirror 200 Image forming unit 303 Laser control unit 304a to 304d Laser driver

In order to achieve the above object, an image forming apparatus according to a first aspect of the present invention is a rotary polygon mirror that is rotationally driven and provided with two different light sources for emitting a laser beam and four reflecting surfaces , and the four reflections Depending on the surface, the laser beam emitted from one light source deflects the laser beam so as to scan the first photosensitive member, and the laser beam emitted from the other light source scans the second photosensitive member. and a rotary polygon mirror for deflecting the laser beam, incident on the reflecting surface of the laser beam and is parallel to the rotating polygon mirror with each other emitted from the laser beam and the other light source emitted from the one light source and whether the other light source to the reflective surface adjacent to the upstream side in the rotational direction of said rotary polygonal mirror with respect to the reflecting surface of the laser beam emitted is incident from the one light source of said four reflecting surfaces In the image forming apparatus into which the laser beam emitted from the light source is incident , a plurality of laser drivers separately provided for the one light source and the other light source and driving the respective light sources, and the plurality of laser drivers are provided. And a control unit that transmits to the substrate a control signal for switching the operation mode of the plurality of laser drivers, the signal line of the control signal being not mounted on the substrate. A branch wiring for inputting the control signal transmitted from the control unit to the substrate from the control unit via a common electric wire by the common electric wire is formed on the substrate. And the plurality of laser drivers are operated in respective operation modes based on the control signal input through the common wire and the branch wiring. And switches.
In order to achieve the above object, an image forming apparatus according to claim 6 comprises a first light source, a second light source, a third light source, a fourth light source, and four reflecting surfaces. A rotating polygon mirror that is rotationally driven, and deflects the laser beam so that the laser beam emitted from the first light source scans the first photosensitive member by the four reflecting surfaces; The laser beam emitted from the light source scans the second photosensitive member, and the laser beam emitted from the third light source scans the third photosensitive member And a polygon mirror that deflects the light beam so that the laser beam emitted from the fourth light source scans the fourth photosensitive member, and the fourth reflecting surface A laser beam emitted from the light source 1 and The laser beam emitted from the second light source is incident on the same reflection surface, and the light beam emitted from the third light source to the reflection surface adjacent to the reflection surface on the upstream side in the rotational direction of the rotary polygon mirror The laser beam emitted from the fourth light source is incident, and the laser beam emitted from the first light source and the laser beam emitted from the second light source are parallel to the rotary polygon mirror with a fixed interval. In the image forming apparatus, the laser beam which is incident and which is emitted from the third light source and the laser beam which is emitted from the fourth light source is incident on the rotating polygon mirror in parallel with the predetermined interval, A plurality of laser drivers individually provided to the light source, the second light source, the third light source, and the fourth light source and driving the respective light sources; A control unit for transmitting a control signal for switching the operation mode of the plurality of laser drivers to the substrate, the control signal being not mounted on the substrate; A signal line is transmitted from the control unit to the substrate by a common electric wire, and a branch for inputting the control signal transmitted from the control unit to the plurality of laser drivers via the common electric wire to the substrate A wiring is formed, and the plurality of laser drivers switch the respective operation modes based on the common electric wire and the control signal input through the branch wiring.

Claims (4)

A first light source,
A second light source,
A rotary polygon mirror having four reflective surfaces and being rotationally driven, wherein the four reflective surfaces allow the light beam emitted from the first light source to scan the first photosensitive member. A polygon mirror that deflects the light beam so that the light beam emitted from the second light source scans the second photosensitive member;
The light path of the light beam emitted from the first light source toward the rotary polygon mirror and the light path of the light beam emitted from the second light source toward the rotary polygon mirror become parallel to each other. The light emitted from the second light source to the reflecting surface adjacent to the upstream side of the rotating polygon mirror in the rotational direction with respect to the reflecting surface on which the light beam emitted from the first light source is incident among the four reflecting surfaces. A housing in which the first light source, the second light source, and the rotating polygon mirror are disposed such that the beam is incident;
First driving means for driving the first light source according to any one of a plurality of operation modes;
Second driving means for driving the second light source according to any one of the plurality of operation modes;
The same timing of the same operation mode signal to the first drive means and the second drive means so that the operation mode of the first light source and the operation mode of the second light source become the same. And control means for outputting the image data.   And a wire connected to the control means and the first drive means to transmit the operation mode signal from the control means to the first drive means, and the control means to the second drive means In order to transmit the operation mode signal, the wiring is branched between the first control unit and the first driving unit, and the branched wiring is connected to the second driving unit. The image forming apparatus according to claim 1, wherein A first wire connected to the control means and the first drive means; and a second wire connected to the control means and the second drive means.
The control means transmits the operation mode signal to the first drive means through the first wiring, and transmits the operation mode signal to the second drive means through the second wiring. The image forming apparatus according to claim 1. And a signal generation unit that receives the light beam emitted from the second light source and outputs a synchronization signal in response to the light beam being received.
The control means switches the operation mode signal to be transmitted to the first drive means and the second drive means based on the generation timing of the synchronization signal generated by the signal generation means. 4. An image forming apparatus according to any one of items 1 to 3.

Images