JP4170029B2 - Focus adjustment apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus that adjusts the focus of an optical writing apparatus that forms an electrostatic latent image on the surface of an image carrier by irradiating light modulated based on image data. The present invention also relates to an image forming apparatus provided with the focus adjusting device.
[0002]
[Prior art]
In an electrophotographic image forming apparatus such as a copying machine or a laser printer, an electrostatic latent image is formed on the surface of an image carrier by irradiating light modulated based on digitized image data from a light emitting element of an optical writing device. After forming the electrostatic latent image with a developer, the image is transferred to a recording medium such as paper to form an image. There are two types of optical writing apparatuses used in this image forming apparatus, a laser system and a solid scanning system.
[0003]
Since the laser type optical writing device deflects the laser beam emitted from one laser light emitting element at a wide angle by a rotary polygon mirror or the like, an optical system having a long optical path length is required, and the image forming apparatus can be downsized. Realization of cost reduction becomes difficult.
[0004]
On the other hand, the solid-state optical writing device has a number of light emitting elements such as LEDs and ELs arranged in an array corresponding to one line (about 7000 when supporting an A3 size image with a resolution of 600 dpi). The light from each element is condensed by a lens array composed of a SELFOC lens or the like and irradiated onto the surface of the image carrier. That is, in the solid scanning optical writing device, each light-emitting element writes one pixel on the image carrier, so that the optical path length of the optical system can be shortened, and the image forming apparatus can be easily reduced in size and cost. . For this reason, in recent years, a solid scanning type optical writing apparatus has been dominant.
[0005]
If the optical path length is too short in a solid scanning optical writing device, the focal depth becomes shallow and defocusing (focal defocus) is likely to occur. This defocusing is the distance between the optical writing device and the image carrier. It can be solved by adjusting. Therefore, when assembling the image forming apparatus, an operator manually adjusts the distance between the optical writing device and the image carrier while observing the image obtained by the image formation with the naked eye.
[0006]
However, in the conventional adjustment work of the distance between the optical writing device and the image carrier, all of the very complicated and difficult work is relied on manually, so that the adjustment work requires skill and the work time is prolonged. There is a problem to do.
[0007]
As a technique relating to such focus adjustment, for example, (1) Japanese Patent Application Laid-Open No. 62-166372 discloses that an optical writing device is mounted on an image carrier so that the focal length is non-uniform in the arrangement direction of light emitting elements. After the image is formed in an inclined state, the optical writing device is moved in parallel while maintaining the inclination angle, and the image is formed again. A configuration is disclosed in which the deviation amount of the tilt angle and focal length of the image carrier relative to the optical writing device is calculated based on the information.
[0008]
Further, (2) Japanese Patent Application Laid-Open No. 7-270673 discloses that an optical pattern is formed by repeatedly turning on and off the optical writing device while changing the focal length, and the optical writing device is formed at the position where the image density is lowest. A configuration in which is arranged is disclosed.
[0009]
[Problems to be solved by the invention]
However, in the configuration disclosed in (1) above, it is necessary to perform complicated calculations for focus adjustment. The configuration disclosed in the above item (2) relates to an image carrier for binary images, and does not describe any focus adjustment technique for an image carrier for multi-value images.
[0010]
An object of the present invention is to provide a focus adjusting apparatus and an image forming apparatus capable of easily and accurately performing focus adjustment of an optical writing device with respect to an image carrier regardless of whether it is for a binary image or a multi-value image. Is to provide.
[0011]
[Means for Solving the Problems]
(1) A focal point that matches the focal position of light emitted from an optical writing device provided with a plurality of light emitting elements along the main scanning direction so as to face the image forming area of the image carrier on the surface of the image carrier. An adjustment device,
  A displacement mechanism for displacing the optical writing device from a predicted in-focus position in a direction approaching or separating from the image carrier before focus adjustment;
  RespectivelyCorrespond to different adjustment amounts and have different densitiesStorage means for storing a pattern image composed of a plurality of patterns;
  AboveBy developing the surface of the image carrier irradiated with light from the optical writing device based on the pattern image stored in the storage means, the respective densities are different.MultipleImage forming means for performing image forming processing for forming a pattern on a recording medium;
  AboveFormed on the recording medium by image forming meansCorresponds to one of multiple patternsAn input unit for receiving an input of an adjustment amount,
  The displacement mechanism isAboveBased on the adjustment amount input to the input unit, the surface of the image carrierAboveDisplace the position of the optical writing device,AboveThe focus position of the light irradiated from the optical writing device is made to coincide with the surface of the image carrier.
[0012]
  In this configuration, eachCorrespond to different adjustment amounts and have different densitiesImage formation processing based on a pattern image composed of multiple patterns is performed. And paintingImage formation processingFormed on the recording medium byPatterneitherWhen an adjustment amount corresponding to the above is input at the input unit, the position of the optical writing device is displaced based on the adjustment amount so that the light focus of the light emitting element coincides with the surface of the image carrier. If the focal point of the light emitting element of the optical writing device does not coincide with the surface of the image carrier, the focal point is blurred, so that the density of each pattern decreases, and the error of the focal point of the optical writing device with respect to the surface of the image carrier increases. Accordingly, an image is not formed on the recording medium in order from the pattern having the lower density. Therefore, the optical writing device is automatically displaced so that the optical writing device is positioned at an appropriate position with respect to the surface of the image carrier, based on the adjustment amount corresponding to the pattern not formed on the recording medium. Is done.
  Further, in this configuration, the optical writing device is mounted in a position displaced in advance in a direction approaching or separating from the image carrier from a position where the light focus of the light emitting element is expected to coincide with the surface of the image carrier. In this state, the pattern image is formed. Therefore, a direction in which the optical writing device should be moved in order to adjust the position of the optical writing device to an appropriate position is specified in advance, and from an image on a single recording medium as a result of image formation processing based on the pattern image, An adjustment method for making the position of the optical writing device appropriate is recognized accurately.
[0013]
(2) The displacement mechanism is
  AboveA holding member for holding the optical writing device;
  The holding member is holding the holding memberThe position of the optical writing deviceAboveDirection in which the optical writing device and the surface of the image carrier are close to or separated from each otherDisplace toMoving memberWhen,
  AboveA driving source for supplying a driving force for displacing the position of the optical writing device to the moving member;
  According to the adjustment amount input to the input unitAboveDrive control means for controlling the operation of the drive source;
It is characterized by including.
[0014]
  In this configuration, the optical writing device,The movable member is held by the holding member in a state in which the position of the light emitting element with respect to the light irradiation direction relative to the surface of the image carrier is freely displaceable.The AndFrom the drive source controlled by the drive control means,Driving force for displacing the position of the optical writing device relative to the moving member isEntered in the input sectionSupplied according to the adjustment amount. Therefore, the optical writing device is displaced by the driving force supplied from the drive control means to the moving member according to the adjustment amount so that the light focus of the light emitting element coincides with the surface of the image carrier.Is done. And the optical writing deviceThe holding member is securely held in the displaced state.
[0021]
(3)The image forming unit includes:In the image forming process,Each pixel diameter is changed according to the density of each pattern composing the pattern imageAnd
Each pattern constituting the pattern image continues substantially throughout the main scanning direction in the image forming area of the image carrier.It is characterized by that.
[0022]
  In this configuration, during the focus adjustment operation of the optical writing device, a pattern image composed of a plurality of patterns having a density difference by changing each pixel diameter is formed. Therefore, a plurality of patterns used for determining the adjustment amount at the time of the focus adjustment operation of the optical writing device in the image forming apparatus using the image carrier formed of the multi-value image photosensitive material are appropriately formed at different densities from each other, The difference in density of each pattern is clearly expressed on the recording medium.
Further, in this configuration, the focus adjustment operation of the optical writing device is performed based on the result of the image forming process based on the pattern image including a plurality of patterns that are continuous over substantially the entire area in the main scanning direction in the optical writing device. Therefore, an error from the appropriate position of the optical writing device in the substantially entire area in the main scanning direction is recognized from the density of the image on the recording medium, and the optical writing apparatus is biased to one side with respect to the appropriate position in the entire area in the main scanning direction. In the main scanning direction of the optical writing device is in a proper position, and the adjustment direction of the optical writing device is accurately identified. The
[0023]
(4) BeforeThe image forming meansIn the image forming process,Binary patterns with different number of pixels are formed according to the density of each pattern composing the pattern imageAnd
Each pattern constituting the pattern image continues substantially throughout the main scanning direction in the image forming area of the image carrier.It is characterized by that.
[0024]
  In this configuration, during the focus adjustment operation of the optical writing device, a pattern image composed of a plurality of patterns having a density difference by changing the number of pixels in the predetermined area is formed. Accordingly, a plurality of patterns used for determining the adjustment amount at the time of the focus adjustment operation of the optical writing apparatus in the image forming apparatus using the image carrier formed of the binary image photosensitive material are appropriately formed with different densities, The difference in density of each pattern is clearly expressed on the recording medium.
Further, in this configuration, the focus adjustment operation of the optical writing device is performed based on the result of the image forming process based on the pattern image including a plurality of patterns that are continuous over substantially the entire area in the main scanning direction in the optical writing device. Therefore, an error from the appropriate position of the optical writing device in the substantially entire area in the main scanning direction is recognized from the density of the image on the recording medium, and the optical writing apparatus is biased to one side with respect to the appropriate position in the entire area in the main scanning direction. In the main scanning direction of the optical writing device is in a proper position, and the adjustment direction of the optical writing device is accurately identified. The
[0025]
(5)The image forming unit includes:In the image forming process,Controls the light emission time of the light emitting element according to the density of each pattern composing the pattern imageAnd
Each pattern constituting the pattern image continues substantially throughout the main scanning direction in the image forming area of the image carrier.It is characterized by that.
[0026]
  In this configuration, during the focus adjustment operation of the optical writing device, each light emitting element of the optical writing device is formed to form a pattern image composed of a plurality of patterns with different pixel diameters to give density differences. The light emission time is controlled. Therefore, the pattern image used for determining the adjustment amount during the focus adjustment operation of the optical writing device in the image forming apparatus using the image carrier formed of the multi-value image photosensitive material can be easily controlled by controlling the light emission time of the light emitting element. Formed.
Further, in this configuration, the focus adjustment operation of the optical writing device is performed based on the result of the image forming process based on the pattern image including a plurality of patterns that are continuous over substantially the entire area in the main scanning direction in the optical writing device. Therefore, an error from the appropriate position of the optical writing device in the substantially entire area in the main scanning direction is recognized from the density of the image on the recording medium, and the optical writing apparatus is biased to one side with respect to the appropriate position in the entire area in the main scanning direction. In the main scanning direction of the optical writing device is in a proper position, and the adjustment direction of the optical writing device is accurately identified. The
[0027]
(6)The image forming unit includes:In the image forming process,Controls the light emission output of the light emitting element according to the density of each pattern constituting the pattern imageAnd
Each pattern constituting the pattern image continues substantially throughout the main scanning direction in the image forming area of the image carrier.It is characterized by that.
[0028]
  In this configuration, during the focus adjustment operation of the optical writing device, each light emitting element of the optical writing device is formed to form a pattern image composed of a plurality of patterns with different pixel diameters to give density differences. The light emission output is controlled. Therefore, the pattern image used for determining the adjustment amount during the focus adjustment operation of the optical writing apparatus in the image forming apparatus using the image carrier formed of the multi-value image photosensitive material can be easily controlled by controlling the light emission output of the light emitting element. Formed.
Further, in this configuration, the focus adjustment operation of the optical writing device is performed based on the result of the image forming process based on the pattern image including a plurality of patterns that are continuous over substantially the entire area in the main scanning direction in the optical writing device. Therefore, an error from the appropriate position of the optical writing device in the substantially entire area in the main scanning direction is recognized from the density of the image on the recording medium, and the optical writing apparatus is biased to one side with respect to the appropriate position in the entire area in the main scanning direction. In the main scanning direction of the optical writing device is in a proper position, and the adjustment direction of the optical writing device is accurately identified. The
[0033]
(7)An optical writing device provided with a plurality of light emitting elements facing the image forming area of the image carrier along the main scanning direction;
  The focus adjusting apparatus according to any one of (1) to (6)When,With
  The image forming means includes theThe position relative to the image carrier was adjusted by the focus adjustment device.AboveFrom optical writing device,Based on image dataTheLightBy developing the image carrier surface,An image forming apparatus for performing electrophotographic image formation.
[0034]
  In this configuration,Entered in the input sectionBased on the adjustment amount, the position of the optical writing device is displaced so that the light focus of the light emitting element coincides with the surface of the image carrier.,Image formIt depends on the image forming deviceDone. Therefore, an accurate image is formed in a state where the light emitted from the light emitting element of the optical writing device forms an image on the surface of the image carrier.
[0035]
(8)Formed on the recording mediumImage reading device for reading imagesWhen,
  AboveBy image forming meansAboverecoding mediaUpFormed inMultiple patternsTheAboveScanned with an image readerCorresponds to the pattern with the lowest density among multiple patternsControl means for determining the adjustment amountAnd comprising
The displacement mechanism displaces the position of the optical writing device relative to the surface of the image carrier based on the adjustment amount determined by the control means, and the focal position of light emitted from the optical writing device is image-bearing. Match the body surfaceAn image forming apparatus.
[0036]
  In this configuration, image forming processingByrecoding mediaEach pattern formed onIs read by the image reader.The AndBased on the read data, the adjustment amount of the position of the optical writing device isBy control meansIt is determined. Therefore, at the time of the focus adjustment operation, the recording medium on which the image is formed by the image forming process based on the pattern image is set in the image reading apparatus and the reading process is performed. The position of the optical writing device is automatically displaced so that the light focus of the light emitting element coincides with the surface of the image carrier.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a diagram showing a configuration of a digital image forming apparatus to which a focus adjusting apparatus according to an embodiment of the present invention is applied. A document table 111 made of transparent glass is disposed on the upper surface of the digital image forming apparatus 1. The upper surface of the document table 111 is covered with an automatic document feeder (ADF) 112 so as to be freely opened and closed. The ADF 112 automatically feeds documents set on the document setting tray one by one onto the document table 111.
[0038]
In the digital image forming apparatus 1, an image reading unit 110 is disposed below the document table 111. The image reading unit 110 includes a first scanning unit 113, a second scanning unit 114, an optical lens 115, and a photoelectric conversion element (CCD line sensor) 116. The scanning unit 113 is equipped with an exposure lamp unit that exposes the document image surface and a first mirror that reflects the reflected light on the document image surface in a predetermined direction. The scanning unit 114 is equipped with a second mirror and a third mirror that guide the reflected light on the document image surface via the first mirror to the CCD line sensor 116. The optical lens 115 forms an image of the reflected light on the document image surface on the CCD line sensor 116. The image reading unit 110 is an image reading apparatus according to the present invention. By an operation associated with the ADF 112, an image of a document that is automatically fed by the ADF 112 onto the document table 111 is automatically transferred to a predetermined exposure position. Read in.
[0039]
The image of the document read by the image reading unit 110 is sent as image data to an image processing unit (not shown), and is stored in a memory after being subjected to predetermined image processing. The image data in the memory is transferred by the control unit 200 to the LED head 227 which is a solid scanning optical writing device of the image forming unit 210 in accordance with an output instruction.
[0040]
The LED head 227 is supplied with image data stored in a memory or image data transferred from an external device by the control unit 200. The LED head 227 is a light-emitting element array that is turned on according to supplied image data, and a lens such as a SELFOC lens that forms an image of light emitted from the light-emitting element array on a photosensitive drum 222 that is an image carrier. The surface of the photosensitive drum 222 that is provided with an array and is uniformly charged to a predetermined potential by a charger 223 described later is exposed with light modulated based on image data, and an electrostatic latent image is formed on the surface of the photosensitive drum 222. Form.
[0041]
The image forming unit 210, which is an image forming unit according to the present invention, supplies a toner to the surface of the photosensitive drum 222 and a charger 223 for charging the surface of the photosensitive drum 222 to a predetermined potential around the photosensitive drum 222. Then, a developing device 224 that visualizes the electrostatic latent image into a toner image, a roller method that transfers the toner image formed on the surface of the photosensitive drum 222 to a sheet as a recording medium, a brush method, and a charger method shown in the figure A transfer unit 225, a charge remover 229 that discharges paper from the surface of the photoconductive drum 222 easily, a cleaning unit 226 that collects toner remaining on the surface of the photoconductive drum 222, and the like.
[0042]
The sheet on which the toner image is transferred in the image forming unit 210 is conveyed to the fixing unit 217 and is heated and pressurized. As a result, the toner image transferred onto the paper is once melted and then firmly fixed on the paper to form an image.
[0043]
In addition to the fixing unit 217, on the downstream side of the image forming unit 210 in the paper conveyance direction inside the digital image forming apparatus 1, both sides of the paper are reversed after the front and rear edges of the paper are reversed to form an image again on the back surface of the paper. A switchback conveyance path 221 leading to the unit 255, a post-processing mechanism for performing stapling processing on the paper on which the image is formed, and a post-processing device 260 having an elevating tray 261 that moves up and down according to the number of sheets stored. ing. The sheet on which the toner image has been fixed by passing through the fixing unit 217 selectively passes through the image forming unit 210 and the fixing unit 217 from the switchback conveying path 221 via the duplex unit 255 as needed, The paper is guided into the post-processing device 260 by the paper discharge roller 219, and after being subjected to predetermined post-processing, it is discharged onto the lifting tray 261.
[0044]
In the digital image forming apparatus 1, a paper feeding unit 250 is disposed below the image forming unit 210. The paper feed unit 250 includes a manual feed tray 254, a duplex unit 255, sheet trays 251 to 253, and a sheet conveyance path 256 that conveys the sheet fed from the trays 251 to 254 or the duplex unit 255 to the image forming unit 210. I have. The duplex unit 255 temporarily stores a sheet whose front and rear ends are reversed in the switchback conveyance path 221. The duplex unit 255 can be replaced with a normal paper tray similar to the paper trays 251 to 253.
[0045]
FIG. 2 is a block diagram showing the configuration of the control unit of the digital image forming apparatus. The control unit 200 of the digital image forming apparatus 1 is configured by connecting a pattern data storage unit 204, an image data storage unit 205, and an image data input unit 206 to a CPU 201 having a ROM 202 and a RAM 203. The CPU 200 includes input / output devices such as an operation unit 301, a fixing unit 302, a paper feeding unit 303, a charging unit 304, a developing unit 305, a transfer unit 306, an LED head 227, an ADF 112, an image reading device 110, and adjustment motors 22a and 22b. Is connected. The CPU 201 is a drive control unit and control unit of the present invention, and controls each input / output device in an integrated manner based on a program written in the ROM 202 in advance. Data input / output during this time is temporarily stored in the RAM 203.
[0046]
The pattern data storage unit 204 is a storage unit of the present invention that stores image data of a pattern image to be described later. The image data storage unit 205 stores image data after image processing. The image data input unit 206 receives input of image data from an external device such as a scanner. The operation unit 301 drives a display in an operation panel (not shown) based on display data supplied from the CPU 201 and inputs the contents of key operations in the operation panel by the operator to the CPU 201. The fixing unit 302 drives the heater of the fixing unit 217 based on control data supplied from the CPU 201.
[0047]
The paper feed unit 303 is a motor that supplies rotational force to the paper feed rollers disposed in the trays 251 to 254 or the duplex unit 255 based on the control data supplied from the CPU 201, the transport rollers in the paper transport path 256, and the like. Drive the clutch. The charging unit 304 drives the power supply unit of the charger 223 based on the control data supplied from the CPU 201. The developing unit 305 drives a developing bias power source and a motor of the developing device 224 based on control data supplied from the CPU 201. The transfer unit 306 drives the power supply unit of the transfer unit 225 based on the control data supplied from the CPU 201. The CPU 201 drives the front side adjustment motor 22a and the back side adjustment motor 22b via a driver circuit (not shown). The adjusting motors 22a and 22b will be described later.
[0048]
FIG. 3 is a diagram showing the positional relationship between the LED head and the photosensitive drum in the digital image forming apparatus. The LED head 227 includes an LED array substrate 12 and a lens array 13. On the LED array substrate 12, a plurality of LEDs (light emitting elements) 11 are arranged in an array over substantially the entire area of the surface of the photosensitive drum 222 in the rotation axis direction (main scanning direction). Each LED 11 corresponds to each pixel in the main scanning direction of an image to be formed on the paper P via the surface of the photosensitive drum 222. The lens array 13 is composed of a plurality of lenses facing each LED 11 on the LED array substrate 12.
[0049]
With the LED head 227 positioned at an appropriate distance from the surface of the photosensitive drum 222, the light emitted from each LED 11 based on the image data is coupled to the surface of the photosensitive drum 222 by the lens array 13. Image. Therefore, in order to form an image in which the content of the image data is faithfully reproduced on the paper P, the digital image is set so that the distance of the LED head 227 to the photosensitive drum 222 becomes an appropriate value over the entire region in the main scanning direction. It is necessary to attach the LED head 227 in the forming apparatus 1.
[0050]
FIG. 4 is an external view of the LED head including the adjusting mechanism. The LED head 227 is attached to a predetermined position in the digital image forming apparatus 1 via the adjustment mechanism 2. The adjustment mechanism 2 is provided in the front frame 31 and the rear frame 32 of the digital image forming apparatus 1 and the frame 30 that supports the LED head 227. Both ends of the LED head 227 in the longitudinal direction (main scanning direction) are supported by the front frame 31 and the back frame 32 by support shafts 21 protruding from both ends of the frame 30.
[0051]
The front-side frame 31 and the back-side frame 32 are provided with a front-rear-side adjustment motor 22a and a back-side adjustment motor 22b, respectively. The distance between the LED head 227 and the photosensitive drum 222 is changed by the rotation of the adjusting motors 22a and 22b. After the LED head 227 is mounted at a predetermined position in the digital image forming apparatus 1, the adjustment motors 22 a and 22 b are rotated by a predetermined amount to change the distance between both ends of the LED head 227 and the photosensitive drum 222. The focus of the head 227 is adjusted.
[0052]
FIG. 5 is a diagram showing a configuration of the adjustment mechanism. FIG. 6 is a diagram showing an adjusting operation in the adjusting mechanism. Head support portions 227a are extended and formed at both ends of the LED head 227. The head support portion 227a includes a contact pin 23 and a support pin protruding in a vertical direction (direction indicated by an arrow Y in the drawing) perpendicular to the longitudinal direction of the LED head 227 (main scanning direction indicated by the arrow X in the drawing). 24 is provided.
[0053]
The upper end of the contact pin 23 protruding upward from the head support portion 227a contacts the inclined surface 25a of the moving body 25 slidably fitted to a part of the support shaft 21 from below. The lower end of the support pin 23 protruding downward from the head support portion 227 a is locked to a U-shaped long hole 30 a formed in the frame 30. One end of the LED head 227 is locked to the other end of the spring 26 locked to the frame 30, and is always urged upward by the elastic force of the spring 26.
[0054]
Above the LED head 227, the support shaft 21 is located between the front side frame 31 and the back side frame 32. Spring 27 is fitted on both ends of the support shaft 21. One end of the spring 27 is in contact with the flange portion 21 a protruding from the peripheral surface of the support shaft 21, and the other end of the spring 27 is in contact with the inner surface of the moving body 25 that is externally fitted to the support shaft 21. Therefore, the moving body 25 is urged toward the end of the support shaft 21 by the elastic force of the spring 27.
[0055]
Screw holes 31 a and 32 a into which the adjusting screws 28 a and 28 b are screwed are formed in the front side frame 31 and the back side frame 32 of the digital image forming apparatus 1. The tips of the adjusting screws 28 a and 28 b screwed into the screw holes 31 a and 32 a from the outside of the front side frame 31 and the rear side frame 32 abut on the side surface of the moving body 25. Further, the outer end portions of the front side frame 31 and the rear side frame 32 of the adjustment screws 28a and 28b are respectively connected to the front side adjustment motor 22a and the rear side adjustment motor 22b fixed to the outside of the front side frame 31 and the rear side frame 32. It is fixed to the rotation axis. Therefore, by driving the front-side adjustment motor 22a and the rear-side adjustment motor 22b, the adjustment screws 22a and 22b are rotated, and the moving body 25 is supported by the elastic force of the spring 27 or against the elastic force. 21 is displaced in the direction of arrow X, which is the axial direction of 21 (main scanning direction).
[0056]
When the moving body 25 is displaced in the arrow X direction, the contact position of the upper end of the contact pin 23 on the inclined surface 25a of the moving body 25 changes in the arrow X direction and the arrow Y direction. When the contact position of the upper end of the contact pin 23 on the inclined surface 25a of the moving body 25 changes in the Y direction, the LED head 227 biased upward by the spring 26 is caused by the elastic force of the spring 26, or Displaces in the vertical direction against this elastic force.
[0057]
That is, as shown in FIG. 6, when the front adjustment motor 22a is driven forward to rotate the adjustment screw 28a, and the movable body 25 is retracted in the arrow X1 direction by the elastic force in the arrow Fo direction acting from the spring 27. The position where the upper end of the abutting pin 23 abuts on the inclined surface 25a of the moving body 25 is displaced upward, and the LED head 227 is displaced in the arrow Y1 direction by the elastic force in the arrow Fu direction acting from the spring 26 (not shown). Further, when the adjustment screw 22 is rotated in the opposite direction against the elastic force in the direction of the arrow Fo acting from the spring 27 by driving the front side adjustment motor 22a in the reverse direction, the moving body 25 moves forward in the direction of the arrow X2. The position where the upper end of the contact pin 23 abuts on the inclined surface 25a of the body 25 is displaced downward, and the LED head 227 is displaced in the arrow Y2 direction against the elastic force in the arrow Fu direction acting from the spring 26 (not shown). . The same operation is performed on the back side by the rotational drive of the back side adjustment motor 22b.
[0058]
In this way, the LED head 227 is displaced in the direction of the arrow Y1 or Y2 by the rotation of the adjusting screws 28a and 28b by the rotational drive of the front side adjustment motor 22a and the rear side adjustment motor 22b, and the LED head 227 and the photosensitive drum 222 are moved. The distance H from the surface can be adjusted. As shown in FIG. 5, the adjustment mechanism 2 has the same configuration at both ends of the LED head 227 in the main scanning direction (X direction), and therefore the distance H between the LED head 227 and the surface of the photosensitive drum 222 is set. The adjustment can be made individually at both ends of the LED head 227 in the main scanning direction. Further, the moving amount of the moving body 25 in the arrow X direction is proportional to the rotation amount of the adjusting motors 22a and 22b and the adjusting screws 28a and 28b in a linear function, and the moving body 25 of which the upper end of the contact pin 23 comes into contact. Since the inclined surface is formed by a straight line in a plane including the displacement direction of the moving body 25 and the LED head 227, the displacement amount of the LED head 227 is proportional to the rotation amount of the adjustment motors 22a and 22b in a linear function. That is, the distance H between the LED head 227 and the surface of the photosensitive drum 222 changes at a constant rate according to the rotation amount of the adjustment motors 22a and 22b.
[0059]
In the above configuration, the contact pin 23, the moving body 25, and the adjusting screws 22a and 22b correspond to the moving member of the present invention, the frame 30 also corresponds to the holding member, and the adjusting motors 22a and 22b also correspond to the driving source. To do. Further, the contact pin 23, the moving body 25, the adjusting screws 22a and 22b, the frame 30, and the adjusting motors 22a and 22b constitute the displacement mechanism of the present invention.
[0060]
FIG. 7 is a plan view showing a pattern image used when adjusting the focus of the LED head in the digital image forming apparatus. In the focus adjustment work performed in the digital image forming apparatus 1 in order to accurately reproduce the content of the image data on the paper P by making the distance between the LED head 227 and the surface of the photosensitive drum 222 appropriate, the pattern shown in FIG. An image is formed on the paper P for the image G, and the adjustment screw 22 is operated based on the image formation result.
[0061]
The pattern image G includes nine patterns G1 to G9 having different densities from each other, “F” and “R” characters indicating the front side and the back side, and adjustments according to the densities of the patterns G1 to G9. It is constituted by a numerical value representing the amount (adjustment amount information of the present invention). Each of the patterns G1 to G9 has a strip shape with a length comparable to substantially the entire region in the main scanning direction. The density of each of the patterns G1 to G9 is determined by adjusting the adjustment screw 22 in a predetermined direction from the state in which the LED head 227 is positioned at a focusing position where the light emitted from the LED head 227 forms an image on the surface of the photosensitive drum 222 ( For example, the LED head 227 is rotated in a fixed amount (for example, one rotation) eight times in the direction in which the LED head 227 is separated from the photosensitive drum 222, whereby the LED head 227 is focused on the surface of the photosensitive drum 222. The respective densities at the time of image formation in each of 9 stages gradually separated from.
[0062]
The numerical value given to the right side of each pattern G1 to G9 represents the adjustment amount according to the density, and represents the number of rotations of the adjustment screw 22. For example, the numerical value “1” given to the lightest pattern G1 indicates that the adjustment screw 22 is used when the lightest pattern G1 is not formed on the paper P in the image formation during the focus adjustment operation. It shows that the LED head 227 can be moved to the in-focus position with respect to the surface of the photosensitive drum 222 by making one rotation. This numerical value does not need to be in increments of 1 rotation, and is in increments of 2 rotations, increments of 0.5 rotations, increments of 0.25 rotations, etc., depending on the relationship between the density of the turn and the pitch of the adjusting screw 22, etc. The rotation speed can be operated.
[0063]
The pattern image G is based on the results of image formation in each of nine stages in which the LED head 227 is gradually separated from the focus position with respect to the surface of the photosensitive drum 222 in many digital image forming apparatuses 1. Thus, it is possible to suppress the occurrence of poor adjustment due to individual differences of the LED heads 227.
[0064]
FIG. 8 is a diagram showing a pattern image forming method used for a focus adjustment operation in a digital image forming apparatus using a multi-value image photosensitive material. When the photosensitive drum 222 is formed of a multi-value image photosensitive material, the patterns G1 to G9 are formed by point images having an n-dot interval (n = 5 in the drawing) in both the main scanning direction and the sub-scanning direction. n may be set according to the image forming characteristics, and the positions of the point images are not the same both vertically and horizontally, but may be staggered. The light emission time or light emission output of the LED 11 of the LED array 227 corresponding to each pixel is changed according to the image data to reproduce the densities of the patterns G1 to G9. When the density is high, the light emission time of each LED 11 is lengthened or the light emission output is increased to increase the dot diameter as shown in FIG. 8A, and when the density is low, the light emission time of each LED 11 is shortened or The light emission output is reduced, and each dot diameter is reduced as shown in FIG.
[0065]
FIG. 9 is a diagram showing a pattern image forming method used for a focus adjustment operation in a digital image forming apparatus using a binary image photosensitive material. When the photosensitive drum 222 is composed of a binary image photosensitive material, each dot diameter cannot be changed. Therefore, the density of each of the patterns G1 to G9 is reproduced by changing the number of LEDs 11 that emit light among the LEDs 11 of the LED array 227. When the density is high, the number of LEDs 11 that emit light is increased to increase the number of black pixels as shown in FIG. 9A, and when the density is low, the number of LEDs 11 that emit light is reduced to reduce the number of LEDs 11 shown in FIG. As shown in FIG.
[0066]
FIG. 11 is a flowchart showing a first processing procedure of the focus adjusting apparatus. First, the LED head 227 which is an optical writing device is assembled (s1), and the assembled LED head 227 is mounted on the adjustment mechanism 2 (s2). Here, the CPU 201 of the control unit 200 rotationally drives the adjustment motors 22a and 22b, and sets the LED head 227 at a position shifted from the in-focus position H in a predetermined direction (s3). The LED head 227 set in the adjustment mechanism 2 in this way is attached to the digital image forming apparatus 1 (s4), and image forming processing based on the pattern image G is executed (s5).
[0067]
At the time of focus adjustment work, a focus adjustment screen 310 shown in FIG. 12 is displayed on the display 301 a of the operation unit 301 of the digital image forming apparatus 1. In the focus adjustment screen 310, a front side density state input unit 311 and a back side density state input unit 312 are configured. The front side density state input unit 311 and the back side density state input unit 312 displayed in the display of the operation unit 301 are input units of the present invention, and are formed on the paper P by image forming processing based on the pattern image G in s5. On the front side and back side of the formed image G ′, an input operation of a numerical value added to the reproduced lightest pattern is accepted.
[0068]
When the operator inputs the image forming state on the paper P to the front side density state input unit 311 and the back side density state input unit 312 in accordance with the display of the focus adjustment screen 310 displayed on the display 301a (s6), control is performed. The CPU 201 of the unit 200 rotates the adjustment motors 22a and 22b according to a program stored in the ROM 202 in advance (s7). The ROM 202 stores the relationship between the numerical values input to the front side density state input unit 311 and the back side density state input unit 312 and the rotation amounts of the adjustment motors 22a and 22b. The front side adjustment motor 22a and the back side adjustment motor 22b rotate by the number of times corresponding to the numerical values input to the front side density state input unit 311 and the back side density state input unit 312.
[0069]
As a result, the adjustment screws 28a and 28b rotate by a necessary amount, and the LED head 227 is positioned at the in-focus position H. In this state, the image forming process is performed again, and it is confirmed that the LED head 227 is located at the in-focus position (s8). Note that the process of s8 can be omitted. In this way, the operator reads the formation state of the image G ′ on the paper P obtained by the image formation process based on the pattern image G during the focus adjustment work, and inputs the result to the operation unit 301 as 1. By performing only once, the LED head 227 can be automatically positioned at the in-focus position with respect to the surface of the image carrier 222.
[0070]
As described above, the operator performs the image forming process based on the pattern image G shown in FIG. 7 during the focus adjustment work, and the adjustment motor included in the adjustment mechanism 2 according to the image formation state on the paper P. By rotating and driving 22a and 22b, the distance of the LED head 227 to the surface of the photosensitive drum 222 can be made appropriate. For example, if the image G ′ shown in FIG. 10 is formed on the paper P as a result of the image forming process based on the pattern image G in FIG. 7, the patterns G1 ′ and G2 ′ are not formed on the front side, and the back side Since the patterns G1 ′ to G4 ′ are not formed on the side, the operator inputs the numerical value “3” added to the pattern G3 ′ to the front side density state input unit 311 and is added to the pattern G5 ′. The numerical value “5” is input to the back side density state input unit 312. In response to this, the CPU 201 rotates the front side adjustment motor 22a and the rear side adjustment motor 22b, for example, by rotating and rotating the front side adjustment motor 22a, thereby rotating the photosensitive drum 222 at both ends on the front side and the rear side in the main scanning direction. The distance of the LED head 227 with respect to the surface can be made appropriate.
[0071]
  FIG. 13 shows the first of the focus adjusting apparatus.2It is a flowchart which shows the process sequence of. First, the LED head 227 which is an optical writing device is assembled (s11), and the assembled LED head 227 is mounted on the adjustment mechanism 2 (s12). Here, the CPU 201 of the control unit 200 rotationally drives the adjustment motors 22a and 22b, and sets the LED head 227 at a position shifted from the in-focus position H in a predetermined direction (s13). The LED head 227 set in the adjustment mechanism 2 in this way is attached to the digital image forming apparatus 1 (s14), and an image forming process based on the pattern image G is executed (s15).
[0072]
When the operator operates the start key in the operation unit 301 after placing the paper P on which the image is formed by the image forming process based on the pattern image G in s15 on the document table 111, the CPU 201 of the control unit 200 operates the image. The paper PK on which is formed is read (s16). The CPU 201 reads the numerical value added to the lightest density pattern reproduced on the front side and the back side from the read data of the image formed on the paper P (s17), and corresponds to the read numerical value. The front side adjustment motor 22a and the back side adjustment motor 22b are rotationally driven by the number of times (s18).
[0073]
As a result, the adjustment screws 28a and 28b rotate by a necessary amount, and the LED head 227 is positioned at the in-focus position H. In this state, the image forming process is performed again to confirm that the LED head 227 is positioned at the in-focus position (s19). Note that the process of s19 can be omitted. In this way, the operator reads the formation state of the image G ′ on the paper P obtained by the image formation process based on the pattern image G during the focus adjustment work, and inputs the result to the operation unit 301 as 1. By performing only once, the LED head 227 can be automatically positioned at the in-focus position with respect to the surface of the image carrier 222.
[0074]
By the above processing, the input operation of the amount of deviation of the current position from the appropriate position (focusing position) with respect to the surface of the photosensitive drum 222 of the LED array 227 on the front side and the back side in the main scanning direction or reading processing is performed. The adjustment heads 22a and 22b can be rotationally driven by the number of times corresponding to the amount of deviation to position the LED head 227 at the in-focus position of the photosensitive drum 222.
[0075]
However, it cannot be recognized whether the both ends of the LED head 227 are too close to the photosensitive drum 222 with reference to the proper position. For example, when the image G ′ shown in FIG. 10 is formed on the paper P as a result of the image forming process based on the pattern image G of FIG. 7, the current positional relationship between the LED head 227 and the photosensitive drum 222 is shown in FIG. The state shown in (A) or (B) can be considered.
[0076]
In order to position the entire LED head 227 at the in-focus position H, in the state shown in FIG. 14A, on the front side of the LED head 227, the adjustment screw 28a is rotated twice in the clockwise direction to turn the LED head 227. The position of the LED head 227 needs to be lowered by rotating the adjusting screw 28b four times in the clockwise direction on the back side. 14B, on the front side of the LED head 227, the adjustment screw 28a is rotated twice counterclockwise to raise the position of the LED head 227, and on the back side, the adjustment screw 28b is counterclockwise. It is necessary to raise the position of the LED head 227 by making four rotations in the direction.
[0077]
As described above, since the rotation direction of the adjusting screws 28a and 28b cannot be specified from only one image formation processing result based on the pattern image G, the adjusting screws 28a and 28b are rotated in a predetermined direction as they are. After that, the image forming process based on the pattern image G is performed again, and it is necessary to determine the rotation direction of the adjusting screws 28a and 28b from the results of the two image forming processes.
[0078]
Therefore, when attaching to the digital image forming apparatus 1, the LED head 227 is previously positioned on either the side closer to the photosensitive drum 222 than the in-focus position H or the side separated from the photosensitive drum 222. In this state, an image forming process based on the pattern image G is performed. As a result, the current positional relationship of the LED 227 with respect to the surface of the photosensitive drum 222 is limited to either the state of FIG. 14A or the state of FIG. 14B, and the adjustment screw 22 should be rotated. The direction can be easily recognized.
[0079]
However, for example, when the LED head 227 is attached to the digital image forming apparatus 1 in a state where the LED head 227 is inclined with the front side facing upward, not only the state of FIG. 14B but also the state of FIG. There is sex. In this case, on the front side of the LED head 227, the adjustment screw 28a is rotated twice in the clockwise direction to lower the position of the LED head 227, and on the rear side, the adjustment screw 28b is rotated four times in the counterclockwise direction to adjust the position of the LED head 227. It is necessary to raise.
[0080]
Here, it is also conceivable to save the developer (toner) consumed during the focus adjustment work by forming the pattern image G with a pattern of only both end portions excluding the central portion in the main scanning direction. However, if the pattern image G is formed by omitting the central portion in the main scanning direction, it cannot be determined whether the state is the state of FIG. 14B or the state of FIG. For this reason, it is preferable to form a pattern image continuous in as wide a range as possible in the main scanning direction. In this case, each of the patterns G1 to Gn can be configured by arranging a plurality of patterns having a short length in the main scanning direction in the main scanning direction.
[0081]
In the above embodiment, the monochrome digital image forming apparatus 1 having a single LED head 227 has been described as an example. However, a multicolor digital image forming apparatus in which a plurality of LED heads 227 are arranged is described. The present invention can be carried out in the same way, and a particularly great effect can be obtained.
[0082]
【The invention's effect】
According to the present invention, the following effects can be obtained.
[0083]
(1) Based on an adjustment amount corresponding to the density of each pattern in an image formation processing result based on a pattern image while performing image formation processing based on a pattern image composed of a plurality of patterns having densities corresponding to different adjustment amounts By shifting the position of the optical writing device so that the light focus of the light emitting element coincides with the surface of the image carrier, based on the adjustment amount according to the density of the pattern image not formed on the recording medium, The optical writing device can be automatically displaced so that the optical writing device is located at the in-focus position with respect to the surface of the image carrier, and the focus adjustment operation can be simplified.
[0084]
(2) The optical writing device is held by the holding member in a state where the position of the light emitting element in the light irradiation direction relative to the surface of the image carrier can be displaced by the moving member, and the moving member is moved from the driving source controlled by the drive control means. By supplying a driving force for displacing the position of the optical writing device according to the adjustment amount, the focus of the light of the light emitting element is supplied by the driving force supplied from the drive control means to the moving member according to the adjustment amount. The optical writing device can be securely held by the holding member in a state in which is coincident with the surface of the image carrier.
[0085]
(3) By inputting the adjustment amount determined with reference to the image formation processing result based on the pattern image or the adjustment amount detected from the image formation processing result based on the pattern image to the displacement mechanism via the input unit, The position of the light writing device in the light irradiation direction with respect to the image carrier of the optical writing device is detected from the adjustment amount determined with reference to the image formation processing result based on the pattern image or the image formation processing result based on the pattern image In accordance with the adjusted amount, the light focus of the light emitting element can be accurately displaced so as to coincide with the surface of the image carrier.
[0086]
(4) The light of the light emitting element is adjusted so that the light focus of the light emitting element coincides with the surface of the image carrier based on the adjustment amount according to the read data of the image on the recording medium, which is the image formation processing result based on the pattern image By displacing the position of the optical writing device with respect to the image carrier in the irradiation direction, the recording medium on which the image is formed by the image forming process based on the pattern image is read by the image reading device, and the light focus of the light emitting element is adjusted. The position of the optical writing device with respect to the image carrier in the light irradiation direction of the light emitting element can be automatically displaced so as to coincide with the surface of the image carrier.
[0087]
(5) By performing the focus adjustment operation of the optical writing device based on the image forming processing result based on the pattern image composed of a plurality of patterns that are continuous over substantially the entire region in the main scanning direction in the optical writing device, The error from the appropriate position of the optical writing device in almost the entire area can be recognized or detected from the density of the image on the recording medium, and the optical writing device is biased to one side with respect to the appropriate position over the entire area in the main scanning direction. To determine the direction in which the optical writing device should be adjusted accurately by checking whether the intermediate portion of the optical writing device is in the proper position. Can do.
[0088]
(6) During the focus adjustment operation of the optical writing device, an image formed of a multi-value image photosensitive material is formed by forming a pattern image formed of a plurality of patterns with different pixel diameters to give density differences. A plurality of patterns used for determining an adjustment amount at the time of a focus adjustment operation of an optical writing device in an image forming apparatus using a carrier can be appropriately formed with different densities, and the density difference of each pattern can be recorded as a recording medium. It can be expressed clearly above.
[0089]
(7) At the time of focus adjustment work of the optical writing device, a pattern image constituted by a plurality of patterns having a density difference by changing the number of pixels in a predetermined region is formed, thereby forming a binary image photosensitive material. A plurality of patterns used for determining the adjustment amount at the time of the focus adjustment operation of the optical writing apparatus in the image forming apparatus using the formed image carrier can be appropriately formed with different densities, and the difference in density of each pattern Can be clearly expressed on the recording medium.
[0090]
(8) The light emission time of each light emitting element of the optical writing device in order to form a pattern image composed of a plurality of patterns with different pixel diameters and giving density differences during the focus adjustment operation of the optical writing device The pattern image used for determining the adjustment amount during the focus adjustment operation of the optical writing device in the image forming apparatus using the image carrier composed of the multi-value image photosensitive material is controlled by controlling the light emission time of the light emitting element. It can be easily formed by controlling.
[0091]
(9) Light emission output of each light emitting element of the optical writing device in order to form a pattern image composed of a plurality of patterns with different pixel diameters and giving density differences during the focus adjustment operation of the optical writing device The pattern image used for determining the adjustment amount during the focus adjustment operation of the optical writing device in the image forming apparatus using the image carrier composed of the multi-value image photosensitive material is controlled by the light emission output of the light emitting element. It can be easily formed by controlling.
[0092]
(10) By forming each pattern constituting a pattern image formed on the recording medium during the focus adjustment operation of the optical writing device by adding adjustment amount information indicating an adjustment amount corresponding to the density of the pattern. The adjustment amount of the focal position of the optical writing device according to the pattern image formation state on the recording medium can be easily recognized or detected with reference to the adjustment amount information.
[0093]
(11) A pattern image in a state where the optical writing device is shifted and mounted at a position displaced in advance in a direction approaching or separating from the image carrier from a position where the light focus of the light emitting element is expected to coincide with the surface of the image carrier. In order to adjust the position of the optical writing apparatus to an appropriate position, the direction in which the optical writing apparatus should be moved is specified in advance, and a single image forming process result based on the pattern image is formed. It is possible to accurately recognize or detect the adjustment direction for making the position of the optical writing device appropriate from the image on the recording medium.
[0094]
(12) The focus of light of the light emitting element is based on the adjustment amount according to the density of each pattern in the image formation processing result based on the pattern image formed by a plurality of patterns having densities corresponding to different adjustment amounts. By performing image forming processing with the position of the optical writing device displaced so as to coincide with the body surface, the light emitted from the light emitting element of the optical writing device forms an image on the surface of the image carrier. An image can be formed accurately.
[0095]
(13) An image reading apparatus reads an image on a recording medium as a result of an image forming process based on a pattern image formed by a plurality of patterns having densities corresponding to different adjustment amounts, and optical writing is performed based on the read data. By determining the amount of adjustment of the position of the device, the light irradiation direction of the light emitting element can be obtained simply by setting the recording medium on which the image is formed by the image forming processing based on the pattern image to the image reading device and performing the reading processing. The position of the optical writing device with respect to the image carrier can be automatically displaced so that the light focus of the light emitting element coincides with the surface of the image carrier, and the focus adjustment operation can be performed.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a digital image forming apparatus including a solid scanning optical writing apparatus in which a focus adjustment method according to an embodiment of the present invention is used.
FIG. 2 is a block diagram illustrating a configuration of a control unit of the digital image forming apparatus.
FIG. 3 is a diagram showing a positional relationship between an LED head and a photosensitive drum in the digital image forming apparatus.
FIG. 4 is an external view of the LED head including an adjustment mechanism.
FIG. 5 is a diagram showing a configuration of the adjustment mechanism.
FIG. 6 is a view showing an adjusting operation in the adjusting mechanism.
FIG. 7 is a plan view showing a pattern image used when adjusting the focus of the LED head in the digital image forming apparatus.
FIG. 8 is a diagram showing a pattern image forming method used for a focus adjustment operation in a digital image forming apparatus using a multi-value image photosensitive material.
FIG. 9 is a diagram showing a pattern image forming method used for a focus adjustment operation in a digital image forming apparatus using a binary image photosensitive material.
FIG. 10 is a plan view illustrating an example of a pattern image formation state on the paper during the focus adjustment operation.
FIG. 11 is a flowchart illustrating a first processing procedure in the focus adjustment apparatus.
FIG. 12 is a diagram illustrating an example of a focus adjustment screen in the operation unit of the image forming apparatus that is sufficient for the time i.
FIG. 13 is a flowchart showing a second processing procedure in the focus adjustment apparatus.
FIG. 14 is a diagram illustrating a state in which the LED head is attached to the photosensitive drum before adjustment during the focus adjustment operation.
[Explanation of symbols]
1-Digital image forming apparatus (image forming apparatus)
2-Adjustment mechanism
22a-front adjustment motor (drive source)
22b—Back adjustment motor (drive source)
23-Contact pin (moving member)
25-Moving object (moving member)
28a, 28b-adjusting screw (moving member)
30-frame (holding member)
201-CPU (drive control means, control means)
222—Photosensitive drum (image carrier)
227-LED head (optical writing device)
G-pattern image
H-Proper position (focus position)
P-paper (recording medium)

Claims (8)

A focus adjustment device that matches a focal position of light emitted from an optical writing device provided with a plurality of light emitting elements along a main scanning direction so as to face an image forming region of an image carrier on the surface of the image carrier. There,
A displacement mechanism for displacing the optical writing device from a predicted in-focus position in a direction approaching or separating from the image carrier before focus adjustment;
Storage means for storing a pattern image composed of a plurality of patterns each corresponding to a different adjustment amount and having different densities ;
Light based on the pattern image stored in said storage means for developing the irradiated surface of the image bearing member from the optical writing device, an image, each image forming processing is performed to form a plurality of patterns different in density in a recording medium Forming means;
An input unit that receives an input of an adjustment amount corresponding to any of a plurality of patterns formed on the recording medium by the image forming unit,
The displacement mechanism, on the basis of the adjustment amount input to the input unit by displacing the position of the optical writing device with respect to the surface of the image bearing member, an image bearing the focal position of the light emitted from the optical writing device A focus adjusting device characterized by matching with a body surface. The displacement mechanism is
A holding member for holding the optical writing device,
A moving member for displacing the position of the optical writing device which is held by the holding member, in a direction with the optical writing device and the image bearing member surface approaches or leaves,
A drive source for supplying a driving force for displacing a position of the optical writing device to the mobile member,
Drive control means for controlling the operation of the driving source according to the adjustment amount input to the input unit,
The focus adjusting apparatus according to claim 1, comprising: The image forming unit changes each pixel diameter according to the density of each pattern constituting the pattern image in the image forming process,
3. The focus adjustment apparatus according to claim 1, wherein the patterns constituting the pattern image are continuous over substantially the entire region in the main scanning direction in the image forming region of the image carrier. In the image forming process, the image forming unit forms a binary pattern having a different number of pixels according to the density of each pattern constituting the pattern image.
3. The focus adjustment apparatus according to claim 1, wherein the patterns constituting the pattern image are continuous over substantially the entire region in the main scanning direction in the image forming region of the image carrier. The image forming means controls the light emission time of the light emitting element according to the density of each pattern constituting the pattern image in the image forming process,
3. The focus adjustment apparatus according to claim 1, wherein the patterns constituting the pattern image are continuous over substantially the entire region in the main scanning direction in the image forming region of the image carrier. The image forming means controls the light emission output of the light emitting element in accordance with the density of each pattern constituting the pattern image in the image forming process,
3. The focus adjustment apparatus according to claim 1, wherein the patterns constituting the pattern image are continuous over substantially the entire region in the main scanning direction in the image forming region of the image carrier. An optical writing device provided with a plurality of light emitting elements facing the image forming area of the image carrier along the main scanning direction;
A focus adjustment device according to any one of claims 1 to 6,
Said image forming means, from the optical writing device with an adjusted position relative to the image bearing member by said focusing apparatus, by light rather based on the image data to develop the irradiated surface of the image bearing member, an electrophotographic system An image forming apparatus that performs image formation. An image reading apparatus for reading an image formed on the recording medium,
Reading a plurality of patterns formed on the recording medium by said image forming means by the image reading apparatus, comprising among the plurality of patterns read, and control means for determining an adjustment amount corresponding to the pattern with the thinnest concentration, ,
The displacement mechanism displaces the position of the optical writing device relative to the surface of the image carrier based on the adjustment amount determined by the control means, and the focal position of light emitted from the optical writing device is image-bearing. The image forming apparatus according to claim 7, wherein the image forming apparatus matches the body surface .

Images