JP2007128040A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that failure such as the wasteful consumption of toner and the back surface staining of recording paper occurs when a light emitting element such as an organic electro-luminescent element constituting an exposure device emits light so that the exposure of the light emitting element may be measured between paper and paper in the midst of image forming operation. <P>SOLUTION: The image forming apparatus includes: a controller 41 setting exposure of an organic electro-luminescent element 63 used as a light emitting element; and an exposure sensor unit 57 measuring the exposure of the organic electro-luminescent element 63. The controller 41 sets exposure so that the exposure of the organic electro-luminescent element 63 when the exposure of the organic electro-luminescent element 63 is measured is smaller than the exposure when images are formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus equipped with an exposure apparatus having a light emitting element array configured by arranging light emitting elements in a line, and more particularly to an image forming apparatus configured to be able to correct an exposure amount of a light emitting element in the exposure apparatus.

  A photosensitive body charged in advance at a predetermined potential is exposed according to image information to form an electrostatic latent image, the electrostatic latent image is developed with toner, and the visualized toner image is transferred to a recording paper. As an exposure device used in an image forming apparatus applying the so-called electrophotographic process to obtain an image by heating and fixing, a light beam using a laser diode as a light source passes through a rotating polygonal mirror called a polygon mirror on the photoreceptor. Each light emitting unit is formed using a method of forming an electrostatic latent image by scanning, and a light emitting element array in which light emitting elements (hereinafter referred to as LEDs) and organic electroluminescent materials are arranged in a line. There is known a system in which an electrostatic latent image is formed on a photoreceptor by individually controlling lighting (ON / OFF).

  In general, an exposure apparatus including a light-emitting element array using LEDs or organic electroluminescent materials as a constituent element selectively illuminates each light-emitting element in the very vicinity of the photoconductor to irradiate the photoconductor with exposure light. The image forming apparatus equipped with a laser diode has no moving parts like a rotating polygon mirror in an image forming apparatus using a laser diode, and has high reliability and quietness. A large optical space serving as a path for the image forming apparatus is unnecessary, and the image forming apparatus can be downsized.

  In particular, an exposure apparatus equipped with an organic electroluminescence element as a light emitting element integrates a driving circuit composed of a switching element composed of a thin film transistor (hereinafter referred to as TFT) on a substrate such as glass and the organic electroluminescence element. Therefore, the structure and manufacturing process are simple, and there is a possibility that further downsizing and cost reduction can be realized as compared with an exposure apparatus in which an LED is mounted as a light emitting element.

However, on the other hand, it is known that the organic electroluminescence element undergoes so-called light quantity deterioration in which the light emission luminance gradually decreases with the driving thereof. An organic electroluminescence element applied to a general display device or the like has a light emission luminance of about 1000 [cd / m ² ] at most, but is applied to an exposure device mounted on an image forming apparatus such as an electrophotographic apparatus. For example, assuming that the specifications of an image forming apparatus are 600 dpi (dot / inch) and 20 ppm (pages / minute), the organic electroluminescence element is required to have a luminance of 10000 [cd / m ² ] or more. The driving conditions are very severe with high voltage and large current. For this reason, the organic electroluminescence element applied to the exposure apparatus is more susceptible to the deterioration of the amount of light than that applied to the display apparatus, so that the exposure amount of each organic electroluminescence element is equal to the initial state. In order to maintain it, some exposure correction is required.

  It is also known that the light emission luminance of an organic electroluminescence element has temperature dependence. This temperature dependency is determined by the organic material constituting the organic electroluminescence element, and can have both positive characteristics and negative characteristics. The above-described image forming process of the electrophotographic apparatus includes a step of fixing the toner image on the recording paper by heat and pressure. Since the apparatus has a heat source capable of generating a large amount of heat, the temperature change inside the apparatus is prevented. Along with this, the emission luminance of the organic electroluminescence element changes. Also in this case, exposure amount correction for correcting the exposure amount of each organic electroluminescence element is required.

  Now, with regard to exposure amount correction, an image forming apparatus equipped with an exposure apparatus to which a conventional organic electroluminescence element is applied has a configuration disclosed in, for example, (Patent Document 1).

  The exposure apparatus in (Patent Document 1) has a configuration in which a light receiving sensor is arranged on a glass substrate on which an organic electroluminescence element is formed, and the exposure amount of each organic electroluminescence element is detected by this light receiving sensor.

  Further, according to (Patent Document 1), the exposure amount Pgn of the n-th organic electroluminescence element in the exposure apparatus is measured in advance with an inspection jig, and at this time, the exposure amount Phn is also measured with the above-described light receiving sensor, Based on these, a correction coefficient Pgn / Phn is calculated, and this correction coefficient is stored in a storage unit mounted on the exposure apparatus or the image forming apparatus. Then, after incorporating the exposure apparatus into the image forming apparatus, by appropriately determining the new drive current of the organic electroluminescence element based on the light amount detection result by the light receiving sensor described above and the correction coefficient stored in the storage means, The initial exposure amount of the organic electroluminescence device can always be maintained.

Further, according to (Patent Document 1), the exposure amount correction operation can be performed based on an instruction from the printer controller at any time between the initialization operation immediately after the start of the image forming apparatus, the start of printing, and the interval between sheets. Yes.
Japanese Patent Laid-Open No. 2004-082330

  FIG. 16 is a block diagram showing a peripheral configuration of a developing station in a conventional image forming apparatus.

  Hereinafter, the problem to be solved by the invention will be described in detail with reference to FIG.

  In FIG. 16, reference numeral 152 denotes a developing station for developing the latent image recorded on the photosensitive member 158. The developing station 152 is filled with a developer 156 that is a mixture of carrier and toner. Reference numerals 157a and 157b denote stirring paddles for stirring the developer 156. The toner in the developer 156 is charged to a predetermined potential by friction with the carrier by the rotation of the stirring paddles 157a and 157b. By circulating, the toner and the carrier are sufficiently stirred and mixed.

  Reference numeral 158 denotes a photoconductor as an image carrier, and the photoconductor 158 is rotationally driven in a direction D13 by a drive source (not shown). Reference numeral 159 denotes a charger, which charges the surface of the photoreceptor 158 to a predetermined potential. Reference numeral 160 denotes a developing sleeve, and 161 denotes a thinning blade. The developing sleeve 160 has a magnet roll 162 in which a plurality of magnetic poles are formed. The layer thickness of the developer 156 supplied to the surface of the developing sleeve 160 is regulated by the thinning blade 161, and the developing sleeve 160 is rotated in the direction D14 by a driving source (not shown), and this rotation and the magnetic pole of the magnet roll 162 are rotated. The developer 156 is supplied to the surface of the developing sleeve 160 by the action of the above, and an electrostatic latent image formed on the photoconductor 158 is developed by an exposure device 163 described later, and the developer 156 that has not been transferred to the photoconductor 158 is developed. Collected in the developing station 152.

  An exposure apparatus 163 has a light source in which light emitting elements such as LEDs and organic electroluminescence elements are arranged in a row, and forms an electrostatic latent image having a maximum A4 size on the photoconductor 158 according to image data. To do. When a predetermined potential (development bias) is applied to the developing sleeve 160, a potential gradient is generated between the electrostatic latent image portion and the developing sleeve 160, and the Coulomb force is applied to the toner in the developer 156 charged to the predetermined potential. As a result, only the toner of the developer 156 adheres to the photoconductor 158, and the electrostatic latent image is visualized.

  Reference numeral 166 denotes a transfer roller. The transfer roller 166 is provided at a position facing the recording sheet conveyance path 155 with respect to the photoconductor 158, and is rotated in the direction D15 by a driving source (not shown). A predetermined transfer bias is applied to the transfer roller 166, and the toner image formed on the photoconductor 158 is transferred to the recording paper 153 conveyed along the recording paper conveyance path 155.

  In the image forming apparatus having such a configuration, when the light emitting element is turned on in order to detect the light amount of the light emitting element so as to correct the exposure amount, the photosensitive member 158 is exposed as a result.

  The configuration related to the image formation of the image forming apparatus, for example, to perform an error check on the system of the image forming apparatus even at the time of the initialization operation immediately after the start, before the start of printing, etc. Since the elements operate in the same manner as in image formation, the photosensitive member 158 is exposed, and a latent image is formed on the photosensitive member 158 regardless of image formation based on regular image data. This latent image is developed through the above-described process, and as a result, toner adheres to the photoreceptor 158. This phenomenon is caused even when the developing bias applied to the developing sleeve 160 is turned off (that is, even if the Coulomb force for moving the toner to the photosensitive member 158 is not actively applied), a latent image is formed on the photosensitive member 158. If there is a part and a part that is not formed, a potential difference exists between them (that is, a Coulomb force acts in the plane direction between the latent image forming region and the non-latent image forming region of the photoconductor 158). It is a phenomenon that occurs to some extent. For this reason, the toner is unnecessarily consumed regardless of the original image formation.

  When the toner adhering to the photoconductor 158 reaches the transfer roller 166 in this way, even if no transfer bias is applied to the transfer roller 166, the transfer is performed by a force such as a mirror image force or a frictional stress received upon contact with the transfer roller 166. The surface of the roller 166 will be contaminated.

  Once the transfer roller 166 is contaminated with toner, the next time the recording paper 153 is transported to the recording paper transport path 155, no matter how the transfer bias is applied to the transfer roller 166 (the transfer bias transfers the toner). The toner is transferred to the back surface of the recording paper 153 by an action such as a rubbing stress based on a small difference in driving speed between the recording paper 153 conveyed on the recording paper conveyance path 155 and the transfer roller 166. As a result, the back of the recording paper 153 becomes dirty.

  In such a case, it is possible to arrange a cleaning member in the vicinity of the transfer roller 166 to always clean the surface of the transfer roller 166, but this solution stores the cleaning member and the toner after cleaning. This is not a sensible measure because it requires a member to be disposed, which directly leads to an increase in cost and size of the apparatus, and in any case, wasteful consumption of toner cannot be prevented.

  The present invention eliminates waste of toner even when a light emitting element such as an organic electroluminescence element constituting an exposure apparatus is caused to emit light in order to measure the exposure amount of the light emitting element during non-image formation such as a sheet interval in an image forming operation. An object of the present invention is to provide an image forming apparatus that does not cause inconveniences such as unnecessary consumption and dirt on the back side of recording paper.

  An image forming apparatus of the present invention is made in view of the above problems, and has an exposure unit provided with a light emitting element, and is an image forming apparatus that performs image formation by exposing an image carrier by this exposure unit, An exposure amount setting unit that sets an exposure amount of the light emitting element, and an exposure amount measurement unit that measures the exposure amount of the light emitting element, and the exposure amount setting unit is used for measuring the exposure amount of the light emitting element. The exposure amount is set to be lower than the exposure amount at the time of image formation.

  According to the image forming apparatus of the present invention, the exposure amount of the light emitting element is adjusted by the exposure amount setting unit even when the light emitting element constituting the exposure apparatus is turned on to measure the exposure amount of the light emitting element. Since the latent image contributing to development is not substantially formed on the photosensitive member, toner is not developed on the photosensitive member even when the exposure amount of the light emitting element is measured. . Therefore, wasteful consumption of toner can be suppressed, and problems such as recording paper back contamination can be solved.

  The image forming apparatus of the present invention is an image forming apparatus that has an exposure unit provided with a light emitting element and performs image formation by exposing the image carrier with the exposure unit, and sets the exposure amount of the light emitting element. An exposure amount measuring unit that measures the exposure amount of the light emitting element, and the exposure amount setting unit determines the exposure amount of the light emitting element when measuring the exposure amount of the light emitting element. It is configured to be set lower. As a result, even when the light emitting element constituting the exposure unit is turned on to measure the exposure amount of the light emitting element, the exposure amount of the light emitting element is set lower than that at the time of image formation by the exposure amount setting unit. The image (latent image and toner image) is not substantially formed on the image carrier. Therefore, wasteful consumption of toner can be suppressed, and problems such as recording paper back contamination can be solved.

  The present invention also provides an image forming apparatus having a photoconductor as an image carrier on which a latent image is formed by exposure of an exposure unit, and a developing unit that develops and visualizes the latent image formed on the photoconductor. An exposure amount setting unit that sets the exposure amount of the light emitting element and an exposure amount measurement unit that measures the exposure amount of the light emitting element. The exposure amount setting unit is configured to measure the exposure amount of the light emitting element. In addition, the exposure amount of the light emitting element is set to be lower than the exposure amount at which the latent image formed on the photoreceptor is developed. Thus, even when the light emitting element constituting the exposure unit is turned on to measure the exposure amount of the light emitting element, a latent image contributing to development is not substantially formed on the photosensitive member. Even when the exposure amount is measured, the toner is not developed on the photoreceptor. Therefore, wasteful consumption of toner can be suppressed, and problems such as recording paper back contamination can be solved.

  According to the present invention, the application of the bias potential to the developing unit is set to OFF for the region of the photoconductor exposed during the measurement period for measuring the exposure amount of the light emitting element. As a result, wasteful consumption of toner can be suppressed more reliably, and problems such as dirt on the back of the recording paper can be solved.

    In the present invention, the exposure portion is composed of a light emitting element array in which a plurality of light emitting elements are formed in a line. As a result, the space required for exposure is reduced as compared with, for example, a laser printer, and the image forming apparatus can be made compact.

  Further, the present invention has an exposure amount correction unit that corrects the exposure amount of each light emitting element substantially equally based on the measurement result by the exposure amount measurement unit, and the exposure amount setting unit based on the output of the exposure amount correction unit Is to set the exposure amount of each light emitting element when performing image formation. As a result, the amount of light emitted from each light-emitting element constituting the exposure unit can be made uniform to obtain a high-quality image.

  In addition, in the present invention, in image formation over a plurality of pages, when the exposure amount of the light emitting elements is measured in a period corresponding to each page, the exposure amount of some of the light emitting elements provided in the exposure unit. Is to measure. As a result, a sufficient period for measurement can be secured and the exposure amount of the light emitting element can be accurately detected even for a short time such as the interval between pages. At this time, the latent image can be isolated by causing the light emitting elements to emit light discretely, thereby making it more difficult to develop.

  Moreover, this invention comprises a light emitting element by the organic electroluminescent element. Organic electroluminescence elements can be formed on the substrate together with the drive circuit by a relatively simple process, and can be manufactured at low cost, thereby reducing the cost of the exposed area and providing the image forming apparatus at low cost. it can.

  In the present invention, the exposure amount of the light emitting element is measured by the exposure amount measurement unit during non-image formation. Non-image formation refers to the time when an image is not formed on the photosensitive member, for example, when the image forming apparatus is initialized, or between recording sheets (between sheets) when image formation is performed over a plurality of pages. As a result, even when the exposure amount is measured, a high-speed printing operation can be performed without reducing the productivity of image formation.

  According to the present invention, when an image is formed over a plurality of pages, the exposure amount of the light emitting element is measured for a period corresponding to each page, that is, between papers. Thereby, even when the light amount of the light emitting element changes within a short time due to the temperature rise of the light emitting element or the temperature rise of the image forming apparatus, the exposure amount can be corrected in real time.

  The present invention further includes an instruction input unit for inputting a user instruction, and measures the exposure amount of the light emitting element based on the input to the instruction input unit. This makes it possible to maintain high image quality even if there is a sudden environmental change that cannot be followed by exposure amount correction.

  The present invention also provides an image forming apparatus having an exposure unit provided with a light emitting element array in which a plurality of organic electroluminescence elements are formed in a line, and performing image formation by exposing the image carrier with the exposure unit. An exposure amount measuring unit that measures the amount of light emitted from the organic electroluminescence element, and when the amount of light emitted from the organic electroluminescence element is measured by the exposure amount measurement unit, an image is formed on the image carrier. An image formation suppressing portion for suppressing is provided. As a result, even when the organic electroluminescence element constituting the exposure unit is turned on to measure the amount of light emitted from the organic electroluminescence element, the image formation suppression unit suppresses the formation of an image on the image carrier. Therefore, wasteful consumption of toner can be suppressed, and problems such as dirt on the back of the recording paper can be solved.

  According to the present invention, the image carrier is a photoconductor, and the image formation suppression unit is configured to suppress the formation of a latent image on the photoconductor by the exposure unit. Thus, even when the organic electroluminescence element constituting the exposure unit is turned on to measure the amount of light emitted from the organic electroluminescence element, the formation of a latent image on the photoreceptor is suppressed by the image formation suppression unit. Therefore, a toner image is not formed on the photosensitive member, wasteful consumption of toner can be suppressed, and problems such as the backside of recording paper can be solved.

  According to the present invention, the image formation suppressing unit is configured by a light blocking member that is displaceably disposed between the exposure unit and the photosensitive member and blocks light emitted from the exposure unit. As a result, even when the organic electroluminescence element constituting the exposure unit is turned on to measure the amount of light emitted from the organic electroluminescence element, the light blocking member suppresses the formation of a latent image on the photoreceptor. In addition, a toner image is not formed on the photosensitive member, wasteful consumption of toner can be suppressed, and problems such as the backside of recording paper can be eliminated.

  In the present invention, the light blocking member is constituted by a shutter that mechanically displaces. Accordingly, it is possible to prevent the photosensitive member from being exposed to light emitted from the exposure unit with a simple configuration.

  In the present invention, the light blocking member is constituted by a shutter that electrically controls light transmittance. Accordingly, it is possible to prevent the photosensitive member from being exposed to light emitted from the exposure unit with a simple configuration. In addition, since the mechanism is simplified by this, it is possible to prevent the configuration around the exposure unit from becoming complicated.

  In the present invention, the image shape suppressing portion is constituted by an optical path length adjusting member that changes an optical path length between the exposure portion and the photosensitive member. As a result, the light emitted from the exposure unit does not form an image on the photoconductor, so that it is possible to suppress the formation of a latent image on the photoconductor.

  In the present invention, the optical path length adjusting member is configured to change the distance between the exposure unit and the photosensitive member in the optical axis direction of the light emitted from the exposure unit. Thus, with a simple configuration, light emitted from the exposure unit does not form an image on the photoconductor, so that it is possible to suppress the formation of a latent image on the photoconductor.

  In the present invention, the exposure length adjusting member is configured to change the angle formed by the optical axis of the light emitted from the exposure unit and the photosensitive member. As a result, for example, the light emitted from the exposure unit does not form an image on the photoconductor by a simple mechanism such as changing the arrangement angle of the exposure unit, so that it is possible to suppress the formation of a latent image on the photoconductor. it can.

  The present invention also includes an exposure amount setting unit for setting the light emission amount of light emitted from the organic electroluminescence element, and this exposure amount setting unit is used for measuring the light emission amount of light emitted from the organic electroluminescence element. The light emission amount of the organic electroluminescence element is set lower than the light emission amount at the time of image formation to suppress the formation of a latent image on the photoconductor. Thus, even when the organic electroluminescence element constituting the exposure unit is turned on to measure the amount of light emitted from the organic electroluminescence element, the exposure amount of the light emitting element is formed by the exposure amount setting unit. Since it is set lower than the time, an image is not substantially formed on the photoreceptor. Therefore, wasteful consumption of toner can be suppressed, and problems such as recording paper back contamination can be solved.

Example 1
Embodiment 1 of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

  In FIG. 1, an image forming apparatus 1 has four color development stations, a yellow development station 2Y, a magenta development station 2M, a cyan development station 2C, and a black development station 2K, arranged in a stepwise manner in the vertical direction. Is provided with a paper feed tray 4 in which the recording paper 3 is accommodated, and a recording paper transport serving as a transport path for the recording paper 3 supplied from the paper feed tray 4 at locations corresponding to the developing stations 2Y to 2K. The path 5 is configured from the upper side to the lower side in the vertical direction.

  The developing stations 2Y to 2K form toner images of yellow, magenta, cyan, and black sequentially from the upstream side of the recording paper conveyance path 5, and the yellow developing station 2Y is photosensitive to the photoreceptor 8Y and the magenta developing station 2M. 8M, cyan developing station 2C includes a photosensitive member 8C, black developing station 2K includes a photosensitive member 8K, and each developing station 2Y to 2K includes a series of electrophotographic systems such as a developing sleeve and a charger described later. The member which implement | achieves the image development process is included.

  Further, exposure devices 13Y, 13M, 13C, and 13K for exposing the surfaces of the photoreceptors 8Y to 8K to form electrostatic latent images are disposed below the developing stations 2Y to 2K.

  The developing stations 2Y to 2K are different in the color of the filled developer, but the configuration is the same regardless of the development color. Therefore, the development is performed except when it is particularly necessary to clarify the following explanation. A description will be given without specifying specific colors such as the station 2, the photoconductor 8, and the exposure device 13.

  FIG. 2 is a configuration diagram illustrating the periphery of the developing station 2 in the image forming apparatus 1 according to the first exemplary embodiment of the present invention. In FIG. 2, the developing station 2 is filled with a developer 6 which is a mixture of carrier and toner. 7a and 7b are stirring paddles for stirring the developer 6. The toner in the developer 6 is charged to a predetermined potential by friction with the carrier by the rotation of the stirring paddles 7a and 7b. The inside of 2 is sufficiently stirred and mixed. The photoreceptor 8 is rotated in the direction D3 by a driving source (not shown). A charger 9 charges the surface of the photoconductor 8 to a predetermined potential. Reference numeral 10 denotes a developing sleeve, and 11 denotes a thinning blade. The developing sleeve 10 has a magnet roll 12 having a plurality of magnetic poles formed therein. The layer thickness of the developer 6 supplied to the surface of the developing sleeve 10 is regulated by the thinning blade 11 and the developing sleeve 10 is rotated in the direction D4 by a driving source (not shown). The developer 6 is supplied to the surface of the developing sleeve 10 by the action of the above, and an electrostatic latent image formed on the photoconductor 8 is developed by an exposure device 13 described later, and the developer 6 not transferred to the photoconductor 8 is developed. Collected in the developing station 2.

  Reference numeral 13 denotes an exposure apparatus. The exposure apparatus 13 in Example 1 has a light emitting element array in which organic electroluminescence elements as exposure light sources are arranged in a line at a resolution of 600 dpi (dot per inch), and is charged to a predetermined potential by a charger 9. An electrostatic latent image of a maximum A4 size is formed on the photoconductor 8 by selectively turning on / off the organic electroluminescence element according to the image data. Only the toner of the developer 6 supplied to the surface of the developing sleeve 10 adheres to the electrostatic latent image portion, and the electrostatic latent image is visualized.

  As will be described in detail later, the exposure apparatus 13 is provided with an exposure amount sensor unit as an exposure amount measurement unit that measures the exposure amount of the organic electroluminescence element.

  Reference numeral 16 denotes a transfer roller. The transfer roller 16 is provided at a position facing the recording paper conveyance path 5 with respect to the photoconductor 8, and is rotated in the direction D5 by a driving source (not shown). A predetermined transfer bias is applied to the transfer roller 16, and the toner image formed on the photoconductor 8 is transferred to the recording paper 3 conveyed through the recording paper conveyance path 5.

  Hereinafter, returning to FIG.

  A toner bottle 17 stores yellow, magenta, cyan, and black toners. A toner transport pipe (not shown) is provided from the toner bottle 17 to each of the developing stations 2Y to 2K, and supplies toner to each of the developing stations 2Y to 2K.

  Reference numeral 18 denotes a paper feed roller, which rotates in a direction D1 by controlling an electromagnetic clutch (not shown), and feeds the recording paper 3 loaded in the paper feeding tray 4 to the recording paper transport path 5.

  A registration paper 19 and a pinch roller 20 pair are provided in the recording paper conveyance path 5 positioned between the paper supply roller 18 and the transfer portion of the most upstream yellow developing station 2Y as a nip conveyance part on the inlet side. The registration roller 19 and the pinch roller 20 pair temporarily stop the recording paper 3 conveyed by the paper supply roller 18 and convey it in the direction of the yellow developing station 2Y at a predetermined timing. This temporary stop restricts the leading edge of the recording paper 3 in parallel with the axial direction of the registration roller 19 and pinch roller 20 pair, thereby preventing the recording paper 3 from skewing.

  Reference numeral 21 denotes a recording paper passage detection sensor. The recording paper passage detection sensor 21 is constituted by a reflective sensor (photo reflector), and detects the leading edge and the trailing edge of the recording paper 3 based on the presence or absence of reflected light.

  When the power transmission is controlled by an electromagnetic clutch (not shown) and the rotation of the registration roller 19 is started, the recording paper 3 is conveyed in the direction of the yellow developing station 2Y along the recording paper conveyance path 5, but the rotation of the registration roller 19 is started. Starting from the timing, the electrostatic latent image writing timing by the exposure devices 13Y to 13K arranged in the vicinity of the developing stations 2Y to 2K, development bias ON / OFF, transfer bias ON / OFF, etc. Be controlled.

  Hereinafter, the description will be continued with reference to FIG.

  Since the distance from the exposure device 13 shown in FIG. 2 to the development region (near the portion where the distance between the photoconductor 8 and the development sleeve 10 is the narrowest) is a design matter, for example, exposure by the exposure device 13 is started and the photoconductor 8 is started. The time for the latent image formed above to reach the development area is also a design matter.

  In the first embodiment, starting from the rotation start timing of the registration roller 19, as described later, when printing a plurality of pages continuously, between the recording paper and the recording paper conveyed through the recording paper conveyance path 5 (that is, Control is performed so that the exposure amount of the organic electroluminescence element constituting the exposure device 13 is set and turned on and the developing bias is turned off with respect to the latent image position formed on the photosensitive member 8. ing.

  Hereinafter, returning to FIG.

  A fixing device 23 is provided as a nip conveyance section on the exit side in the recording paper conveyance path 5 located further downstream of the black development station 2K on the most downstream side. The fixing device 23 includes a heating roller 24 and a pressure roller 25.

  Reference numeral 27 denotes a temperature sensor for detecting the temperature of the heating roller 24. The temperature sensor 27 is a ceramic semiconductor obtained by sintering at a high temperature using a metal oxide as a main raw material, and can measure the temperature of a contacted object by applying a change in load resistance depending on the temperature. it can. The output of the temperature sensor 27 is input to an engine control unit 42 which will be described later, and the engine control unit 42 controls the power supplied to a heat source (not shown) built in the heating roller 24 based on the output of the temperature sensor 27, The surface temperature of the heating roller 24 is controlled to be about 170 ° C.

  When the recording paper 3 on which the toner image is formed is passed through the nip portion formed by the heating roller 24 and the pressure roller 25 that have been controlled in temperature, the toner image on the recording paper 3 is added to the heating roller 24. The toner image is fixed on the recording paper 3 by being heated and pressurized by the pressure roller 25.

  Reference numeral 28 denotes a recording paper trailing edge detection sensor that monitors the discharge state of the recording paper 3. Reference numeral 32 denotes a toner image detection sensor. The toner image detection sensor 32 is a reflective sensor unit that uses a plurality of light emitting elements (both visible light) having different emission spectra and a single light receiving element, and changes the image color between the background of the recording paper 3 and the image forming portion. Accordingly, the image density is detected by utilizing the fact that the absorption spectrum is different. Further, since the toner image detection sensor 32 can detect not only the image density but also the image forming position, in the image forming apparatus 1 in the first embodiment, two toner image detection sensors 32 are provided in the width direction of the image forming apparatus 1 and the recording paper 3 The image formation timing is controlled based on the detection position of the image position deviation amount detection pattern formed above.

  Reference numeral 33 denotes a recording paper transport drum. The recording paper transport drum 33 is a metal roller whose surface is covered with rubber having a thickness of about 200 μm, and the fixed recording paper 3 is transported along the recording paper transport drum 33 in the direction D2. At this time, the recording sheet 3 is cooled by the recording sheet conveying drum 33 and is bent and conveyed in the direction opposite to the image forming surface. As a result, curling that occurs when a high density image is formed on the entire surface of the recording paper can be greatly reduced. Thereafter, the recording paper 3 is conveyed in the direction D6 by the kicking roller 35 and discharged to the paper discharge tray 39.

  Reference numeral 34 denotes a face-down paper discharge unit. The face-down paper discharge unit 34 is configured to be rotatable about the support member 36. When the face-down paper discharge unit 34 is opened, the recording paper 3 is discharged in the direction D7. In the closed state, the face-down paper discharge unit 34 is formed with ribs 37 along the conveyance path on the back so as to guide the conveyance of the recording sheet 3 together with the recording sheet conveyance drum 33.

  Reference numeral 38 denotes a drive source. In the first embodiment, a stepping motor is employed. A peripheral portion of each developing station 2Y to 2K including a paper feed roller 18, a registration roller 19, a pinch roller 20, photoconductors 8Y to 8K, and a transfer roller 16 (see FIG. 2), a fixing device 23, and a recording paper. The conveying drum 33 and the kicking roller 35 are driven.

  A controller 41 receives image data from a computer (not shown) via an external network, and develops and generates printable image data. As will be described in detail later, a controller CPU (not shown) mounted on the controller 41 receives exposure amount measurement data of an organic electroluminescence element as a light emitting element from the exposure apparatuses 13Y to 13K, and generates exposure amount correction data. And an exposure amount setting unit that sets the exposure amount of the organic electroluminescence element based on the exposure amount correction data.

  Reference numeral 42 denotes an engine control unit. The engine control unit 42 controls the hardware and mechanism of the image forming apparatus 1, forms a color image on the recording paper 3 based on the image data and exposure amount correction data transferred from the controller 41, and the above-described fixing device 23. The overall control of the image forming apparatus 1 including the temperature control of the heating roller 24 is performed.

  Reference numeral 43 denotes a power supply unit. The power supply unit 43 supplies power of a predetermined voltage to the exposure devices 13Y to 13K, the drive source 38, the controller 41, and the engine control unit 42, and supplies power to the heating roller 24 of the fixing device 23. The power supply unit also includes a so-called high-voltage power supply system such as a charging potential for charging the surface of the photoconductor 8, a developing bias applied to the developing sleeve (see FIG. 2), and a transfer bias applied to the transfer roller 16. . The engine control unit 42 controls the power supply unit 43 to adjust not only the ON / OFF of the high-voltage power supply but also the output voltage value and the output current value.

  The power supply unit 43 includes a power supply monitoring unit 44 so that at least the power supply voltage supplied to the engine control unit 42 and the output voltage of the power supply unit 43 can be monitored. This monitor signal is detected by the engine control unit 42 to detect a drop in power supply voltage that occurs when the power switch is turned off or a power failure occurs, and particularly an output abnormality of the high-voltage power supply.

  The operation of the image forming apparatus 1 configured as described above will be described with reference to FIGS.

  In the following description, FIG. 1 is mainly used for the description relating to the overall configuration and operation of the image forming apparatus 1, and the colors are divided into the developing stations 2Y to 2K, the photoconductors 8Y to 8K, and the exposure devices 13Y to 13K. Although described separately, the description relating to a single color, such as exposure and development processes, will be mainly described with reference to FIG. 2, and for the sake of simplicity, description will be made without distinguishing colors such as the developing station 2, the photoconductor 8, and the exposure device 13.

<Initialization operation>
First, an initialization operation when the image forming apparatus 1 is turned on will be described.

  When the power is turned on, an engine control CPU (not shown) mounted in the engine control unit 42 performs an error check on the electrical resources constituting the image forming apparatus 1, that is, a register / memory capable of writing / reading. To do. When this error check is completed, the engine control CPU (not shown) starts to rotate the drive source 38. As described above, the peripheral portion of each developing station 2Y to 2K including the paper feed roller 18, the registration roller 19, the pinch roller 20, the photoconductors 8Y to 8K, and the transfer roller 16 by the driving source 38, the fixing device 23, and the recording paper conveyance The drum 33 and the kicking roller 35 are driven. However, immediately after the power is turned on, the feeding roller 18 and the registration roller 19 involved in the conveyance of the recording paper 3 are immediately turned off by the electromagnetic clutch (not shown) for transmitting the driving force to the recording roller 3 and the recording paper 3 is conveyed. There is no control.

  Hereinafter, the description will be continued with reference to FIG.

  As the driving source 38 (see FIG. 1) rotates, the stirring paddles 7a and 7b and the developing sleeve 10 of the developing station 2 also start to rotate, whereby the developer 6 composed of toner and carrier filled in the developing station 2 is developed. While rotating around the station 2, the toner is given a negative charge by the friction between the toner and the carrier.

  The engine control CPU (not shown) starts the rotation of the drive source 38 (see FIG. 1) and controls the power supply unit 43 (see FIG. 1) to turn on the charger 9 after a predetermined time has elapsed. The surface of the photoconductor 8 is charged to a potential of, for example, −700 V by the charger 9. The photosensitive member 8 is rotated in the direction D3, and the engine control CPU (not shown) determines the power supply unit 43 (FIG. 1) after the charged region reaches the developing region, that is, the closest position between the photosensitive member 8 and the developing sleeve 10. For example, a developing bias of −400 V is applied to the developing sleeve 10. At this time, the surface potential of the photosensitive member 8 is −700 V, and the developing bias applied to the developing sleeve 10 is −400 V. Therefore, the electric lines of force are directed from the developing sleeve 10 to the photosensitive member 8 and have a negative charge. The Coulomb force acting on the toner is in the direction from the photoconductor 8 to the developing sleeve 10. Therefore, the toner does not adhere to the photoreceptor 8.

  As described above, the power supply unit 43 (see FIG. 1) has a function of monitoring an output abnormality (for example, leakage) of the high-voltage power supply, and an engine control CPU (not shown) is connected to the charger 9 and the developing sleeve 10 with high power. It is possible to check for abnormalities when a voltage is applied.

  At the end of the series of initialization operations, an engine control CPU (not shown) executes exposure amount correction of the exposure apparatus 13. An engine control CPU (not shown) mounted on the engine control unit 42 (see FIG. 1) outputs a request to create dummy image information for exposure amount correction to the controller 41 (see FIG. 1). Based on this creation request, the controller 41 (see FIG. 1) generates dummy image information for exposure amount correction, and based on this, the organic electroluminescence elements constituting the exposure apparatus 13 are actually controlled to be turned on at the time of initialization. The In the first embodiment, in synchronism with this lighting control (specifically, based on management by an engine control CPU (not shown)), the exposure amount sensor unit (not shown) provided in the exposure apparatus 13 described above performs organic electroluminescence. The exposure amount of the element is measured, and the exposure amount is corrected so that the exposure amounts of the individual organic electroluminescence elements are substantially equal based on the detection result of the exposure amount. As described above, the exposure amount is measured in a state in which the units relating to image formation such as the photosensitive member 8 and the developing stations 2Y to 2K of the image forming apparatus 1 are driven. This is because when the exposure amount is measured in a state where the rotation of the photosensitive member 8 is stopped, the same portion of the photosensitive member 8 is continuously exposed, and a so-called light exposure state is caused, and the characteristics of the photosensitive member 8 are locally deteriorated. It is. Therefore, it is necessary to measure the exposure amount while at least rotating the photosensitive member 8 and charging the photosensitive member 8 with the charger 9 in order to prevent toner adhesion to the photosensitive member 8.

  As will be described in detail later, the image forming apparatus 1 according to the present invention has an exposure device 13 as an exposure unit provided with a light emitting element (organic electroluminescence element). An image forming apparatus that exposes the body 8 to form an image, and an exposure amount setting unit (a controller CPU mounted on the controller 41) that sets an exposure amount of a light emitting element (organic electroluminescence element); An exposure amount measuring unit (exposure amount sensor unit provided in the above-described exposure apparatus 13) that measures the exposure amount of the element (organic electroluminescence element), and an exposure amount setting unit (controller CPU mounted on the controller 41) Is a light emitting device (organic electroluminescence device) for measuring the exposure amount of a light emitting device (organic electroluminescence device). The exposure of sensing elements) is set lower than the exposure amount when performing image formation.

  That is, the image forming apparatus 1 according to the present invention includes an exposure amount setting unit (controller CPU) that sets the amount of light emitted from the organic electroluminescence element, and the exposure amount setting unit emits the organic electroluminescence element. The amount of light emitted from the organic electroluminescence element when measuring the amount of light emitted is set lower than the amount of light emitted during image formation to suppress the formation of a latent image on the photoconductor.

  Further, the image forming apparatus 1 according to the present invention includes an exposure device 13 as an exposure unit provided with a light emitting element (organic electroluminescence element), a photoreceptor 8 on which a latent image is formed by the exposure device 13, and the photoreceptor 8. A developing unit (developing sleeve 10 constituting the developing station 2) that develops and visualizes the latent image formed on the light-emitting element (organic electroluminescence element), as will be described in detail later. ) For setting the exposure amount (controller CPU mounted on the controller 41), and an exposure amount measuring unit for measuring the exposure amount of the light emitting element (organic electroluminescence element) (provided in the above-described exposure apparatus 13). The exposure amount setting unit (controller CPU mounted on the controller 41) includes a light emitting element (organic elect The exposure amount of the light emitting element (organic electroluminescence element) when measuring the exposure amount of the luminescence element) is set lower than the exposure amount at which the latent image formed on the photoreceptor 8 is developed, and as a result, the photoreceptor 8 is set to an exposure amount at which the latent image formed in 8 is not developed by the developing unit (the developing sleeve 10 constituting the developing station 2).

  Furthermore, in the image forming apparatus 1 according to the present invention, as will be described in detail later, the exposure device 13 as an exposure unit is formed with a plurality of minute light emitting elements (organic electroluminescence elements) arranged in a line. The light emitting element array is used. That is, the exposure apparatus 13 according to the first embodiment includes a so-called solid exposure element.

  As a result, during the initialization operation of the image forming apparatus 1, the organic electroluminescence element as the exposure light source constituting the exposure device 13 emits light, and even if the exposure amount is corrected by measuring the exposure amount, The toner does not adhere and does not waste the toner. Further, toner adheres to the transfer roller 16 that rotates in contact with the photoreceptor 8, and in image formation performed following the initialization operation, the toner attached to the transfer roller 16 adheres to the back surface of the recording paper 3 and the recording paper 3. No pollution.

  In this exposure amount correction, by turning on the organic electroluminescence element, the region where the photosensitive member 8 is exposed is close to the developing sleeve 10 and passes through the so-called development region, that is, measurement for measuring the exposure amount of the organic electroluminescence element. It is desirable to turn off the developing bias applied to the developing sleeve 10 for the region of the photoconductor 8 exposed during the period. This makes it possible to more effectively prevent the toner from adhering to the photoreceptor 8.

<Image forming operation>
Next, the operation of the image forming apparatus 1 during image formation will be described with reference to FIG. 1 and FIG.

  When the image information is transferred from the outside to the controller 41, the controller 41 develops the image information in an image memory (not shown) as binary image data that can be printed. When the development of the image information is completed, a controller CPU (not shown) mounted on the controller 41 issues a startup request to the engine control unit 42. The activation request is received by an engine control CPU (not shown) mounted on the engine control unit 42, and the engine control CPU (not shown) receiving the activation request immediately rotates the drive source 38 to prepare for image formation. To start.

  This process is the same as the above-described <Initialization operation> except for the error check regarding electrical resources, and the engine control CPU (not shown) can measure the above-described exposure amount at this point. However, as will be described later, it takes about 10 seconds to measure the exposure amount, which affects the first print time (time required to print the first first sheet). Accordingly, the exposure amount correction at the time of activation is selected by the user according to an instruction from an operation panel (not shown) or the outside of the image forming apparatus 1 (for example, a computer), that is, an instruction from an instruction input unit for inputting a user instruction. It is possible.

  When the preparation for image formation is completed through the above-described process, an engine control CPU (not shown) mounted on the engine control unit 42 controls an electromagnetic clutch (not shown) to rotate the paper feed roller 18 to perform recording. The conveyance of the paper 3 is started. The paper supply roller 18 is, for example, a half-moon roller that lacks a part of the entire circumference. When the leading edge of the conveyed recording paper 3 is detected by the recording paper passing sensor 21, an engine control CPU (not shown) controls an electromagnetic clutch (not shown) after providing a predetermined delay period to register rollers. 19 is rotated. As the registration roller rotates, the recording paper 3 is supplied to the recording paper conveyance path 5.

  An engine control CPU (not shown) independently controls the electrostatic latent image writing timing by each of the exposure devices 13Y to 13K, starting from the rotation start timing of the registration roller 19. Since the electrostatic latent image writing timing directly affects color misregistration and the like in the image forming apparatus 1, the writing timing is not directly generated by an engine control CPU (not shown). Specifically, an engine control CPU (not shown) presets the electrostatic latent image writing timing by each exposure device 13 in a timer (not shown) such as hardware, and rotates the registration roller 19 described above. As a starting point, timer operations corresponding to the exposure apparatuses 13Y to 13K are simultaneously started. Each timer outputs an image data transfer request to the controller 41 when a preset time has elapsed.

  The controller CPU (not shown) of the controller 41 that has received the image data transfer request is synchronized with the timing signal (clock signal, line synchronization signal, etc.) generated by the timing generation unit (not shown) of the controller 41. The value image data is transferred independently to each of the exposure devices 13Y to 13K. In this way, binary image data is sent to the exposure devices 13Y to 13K, and on / off of the organic electroluminescence elements constituting the exposure devices 13Y to 13K is controlled based on the binary image data, and a photoconductor corresponding to each color. 8Y to 8K are exposed.

  The latent image formed by the exposure is visualized by toner contained in the developer 6 supplied onto the developing sleeve 10 as shown in FIG. The visualized toner images of the respective colors are sequentially transferred to the recording paper 3 conveyed through the recording paper conveyance path 5. The recording paper 3 on which the transfer of the four color toner images has been completed is conveyed to the fixing device 23, and is nipped and conveyed by the overheating roller 24 and the pressure roller 25 constituting the fixing device 23. The toner image is recorded on the recording paper by this heat and pressure. 3 is fixed.

  When the image to be formed is a plurality of pages, the engine control CPU (not shown) detects the trailing edge of the recording paper 3 of the first page by the recording paper passage detection sensor 21 and then temporarily rotates the registration roller 19. Then, after a predetermined time has elapsed, the paper feed roller 18 is rotated to start the conveyance of the next recording paper 3, and after the predetermined time has elapsed, the registration roller 19 is again rotated to start the recording paper 3 of the next page. Is supplied to the recording paper conveyance path 5. Thus, by controlling the rotation ON / OFF timing of the registration roller 19, it is possible to set the sheet interval between the recording sheets 3 when an image is formed over a plurality of pages. The time between the sheets (hereinafter referred to as the sheet interval) varies depending on the specifications of the image forming apparatus 1, but is generally set to about 500 ms. Of course, the normal image forming operation (that is, the exposure operation for the photosensitive member 8 by the exposure device 13) is not performed during the period between the sheets.

  When the image forming apparatus 1 according to the present invention forms a plurality of pages as described above, the light emitting element that constitutes the exposure device 13 during the non-image forming period (ie, the time between sheets) corresponding to each page. (Organic electroluminescence device) is caused to emit light, and the amount of exposure is measured in synchronization therewith. As described in <Initialization Operation>, the exposure amount at this time is controlled to be lower than that during normal image formation, and an exposure amount that does not contribute to development is set.

  As described above, the paper interval in the first embodiment is about 500 ms. As will be described later in detail, as described in the description of <Initialization Operation>, in Example 1, the time required to measure the exposure amount for all the organic electroluminescence elements is about 10 seconds, It is not possible to measure the exposure amount of all organic electroluminescence elements within one paper interval. Therefore, in Example 1, when measuring the exposure amount of an organic electroluminescent element in the period corresponded between each page, the exposure amount of some organic electroluminescent elements is measured among the organic electroluminescent elements which comprise the exposure apparatus 13. FIG. I am doing so.

  Since the paper interval is 500 ms and the exposure measurement period is about 10 seconds, according to a simple calculation, if the paper interval occurs about 20 times, all the organic electroluminescent elements constituting the exposure apparatus 13 The exposure amount can be measured. Of course, the number of pages in a series of print jobs is often less than that, but in such a case, after the print job is completed (when the image forming apparatus 1 shifts to a standby state waiting for a print command), the exposure amount is set. You may make it measure.

  FIG. 3 is a block diagram of the exposure device 13 in the image forming apparatus 1 according to the first embodiment of the present invention.

Hereinafter, the structure of the exposure apparatus 13 will be described in detail with reference to FIG. In FIG. 3, 50 is a colorless and transparent glass substrate. In the first embodiment, borosilicate glass, which is advantageous in terms of cost, is used as the glass substrate 50. However, heat generated from a light emitting element or a control circuit or a drive circuit formed by a thin film transistor on the glass substrate 50 is more efficiently radiated. If necessary, glass containing a thermal conductivity additive factor such as MgO, Al ₂ O ₃ , CaO, ZnO, or quartz may be used.

  On the surface A of the glass substrate 50, an organic electroluminescence element as a light emitting element is formed with a resolution of 600 dpi (dot per inch) in a direction (main scanning direction) perpendicular to the drawing. Reference numeral 51 denotes a lens array in which rod lenses (not shown) made of plastic or glass are arranged in a line, and the light emitted from the organic electroluminescence element formed on the surface A of the glass substrate 50 is erecting at an equal magnification. An image is guided to the surface of the photoconductor 8. The positional relationship among the glass substrate 50, the lens array 51, and the photoconductor 8 is adjusted so that one focal point of the lens array 51 is the surface A of the glass substrate 50 and the other focal point is the surface of the photoconductor 8. . That is, when the distance L1 from the surface A to the surface closer to the lens array 51 and the distance L2 from the other surface of the lens array 51 to the surface of the photosensitive member 8, L1 = L2.

For example, 52 is a relay substrate in which an electronic circuit is formed on a glass epoxy substrate. 53a is a connector A, 53b is a connector B, and the relay board 52 has at least a connector A53.
a and connector B53b are mounted. The relay board 52 temporarily relays image data, exposure amount correction data, and other control signals supplied from the outside to the exposure apparatus 13 via a cable 56 such as a flexible flat cable, etc., via a connector B53b. Passed to the substrate 50.

  Since it is difficult to directly mount the connector on the surface of the glass substrate 50 in consideration of bonding strength and reliability in various environments, FPC is used as a connection means between the connector A53a of the relay substrate 52 and the glass substrate 50 in the first embodiment. (Flexible printed circuit) is employed (not shown), and the glass substrate 50 and FPC are joined using, for example, ACF (anisotropic conductive film), for example, ITO (tin-doped oxide) formed on the glass substrate 50 in advance. Indium) electrode is connected directly.

On the other hand, the connector B53b is a connector for connecting the exposure apparatus 13 to the outside. In general, connection by ACF or the like often has a problem of bonding strength. However, by providing the connector B53b for connecting the exposure apparatus 13 on the relay substrate 52 in this way, the interface directly accessed by the user is provided. Sufficient strength can be ensured.

Reference numeral 54a denotes a casing A which is formed by bending a metal plate, for example. An L-shaped portion 55 is formed on the side of the housing A 54 a facing the photoconductor 8, and the L-shaped portion 55 is formed.
A glass substrate 50 and a lens array 51 are arranged along the line. The end face of the housing A54a on the side of the photoconductor 8 and the end face of the lens array 51 are aligned with each other, and further, one end of the glass substrate 50 is supported by the housing A54a. Is ensured, the positional relationship between the glass substrate 50 and the lens array 51 can be accurately adjusted. As described above, since the casing A 54a is required to have dimensional accuracy, it is preferable that the casing A 54a be made of metal. Further, by making the casing A54a made of metal, it is possible to suppress the influence of noise on electronic components such as a control circuit formed on the glass substrate 50 and an IC chip surface-mounted on the glass substrate 50. is there.

  A housing B is obtained by molding a resin. A notch (not shown) is provided in the vicinity of the connector B53b of the housing B54b, and the user can access the connector B53b from this notch. From the controller 41 (see FIG. 1) already described via the cable 56 connected to the connector B53b to the exposure apparatus 13, image data, exposure amount correction data, control signals such as clock signals and line synchronization signals, and drive power for the control circuit A driving power source for the organic electroluminescence element which is a light emitting element is supplied.

  FIG. 4A is a top view of the glass substrate 50 according to the exposure apparatus 13 in the image forming apparatus 1 of Embodiment 1 of the present invention, and FIG. 4B is an enlarged view of the main part.

  Hereinafter, the configuration of the glass substrate 50 in Example 1 will be described in detail with reference to FIG.

In FIG. 4, a glass substrate 50 is a rectangular substrate having a thickness of about 0.7 mm and at least a long side and a short side, and a plurality of organic electroluminescences that are light emitting elements in the long side direction (main scanning direction). Elements 63 are formed in a row. In the first embodiment, the organic electroluminescence element 63 necessary for at least A4 size (210 mm) exposure is disposed in the long side direction of the glass substrate 50, and the long side direction of the glass substrate 50 is the arrangement space of the drive control unit 58 described later. And 250 mm. In the first embodiment, the glass substrate 50 is described as a rectangle for the sake of simplicity. However, a notch is provided in a part of the glass substrate 50 for positioning when the glass substrate 50 is attached to the housing A 54a. It may be accompanied by deformation.

  58 receives binary image data, exposure correction data, and control signals such as a clock signal and a line synchronization signal supplied from the outside of the glass substrate 50, and controls driving of the organic electroluminescence element 63 based on these signals. The drive control unit includes an interface unit that receives these signals from the outside of the glass substrate 50 and an IC chip (source driver 61) that controls the driving of the organic electroluminescence element 63 based on the control signal received through the interface unit. It is out.

Reference numeral 60 denotes an FPC (flexible printed circuit) as an interface unit for connecting the connector A53a of the relay substrate 52 and the glass substrate 50, and is directly connected to a circuit pattern (not shown) provided on the glass substrate 50 without using a connector or the like. Yes. As already described, binary image data, exposure amount correction data and control signals such as clock signals and line synchronization signals supplied from the outside to the exposure apparatus 13, drive power for the control circuit, and organic electroluminescence elements as light emitting elements The drive power 63 is supplied to the glass substrate 50 through the FPC 60 after passing through the relay substrate 52 shown in FIG.

  Reference numeral 63 denotes an organic electroluminescence element, which is an exposure light source in the exposure apparatus 13. In the first embodiment, 5120 organic electroluminescent elements 63 are formed in a row at a resolution of 600 dpi in the main scanning direction, and each organic electroluminescent element 63 is independently controlled to be turned on / off by a TFT circuit described later. Is done.

  A source driver 61 is supplied as an IC chip for controlling the driving of the organic electroluminescence element 63 and is flip-chip mounted on the glass substrate 50. Considering surface mounting on the glass surface, the source driver 61 adopts a bare chip product. The source driver 61 is supplied with power-related signals such as a power supply, a clock signal, and a line synchronization signal, and 8-bit exposure correction data from the outside of the exposure apparatus 13 via the FPC 60. The source driver 61 is a drive current for the organic electroluminescence element 63, that is, a drive parameter setting unit. More specifically, the exposure amount correction generated by the controller CPU (not shown) mounted on the controller 41 (see FIG. 1), which is the exposure amount correction unit and exposure amount setting unit of the organic electroluminescence element 63. Based on the data, the source driver 61 sets a drive current for driving the individual organic electroluminescence elements 63. The operation of the source driver 61 based on the exposure correction data will be described in detail later.

  In the glass substrate 50, the junction part of the FPC 60 and the source driver 61 are connected via, for example, an ITO circuit pattern (not shown) having a metal formed on the surface thereof, and the source driver 61 as a drive current, that is, a drive parameter setting part. Control signals such as exposure correction data, a clock signal, and a line synchronization signal are input to the FPC 60 via the FPC 60. Thus, the FPC 60 as the interface unit and the source driver 61 as the drive parameter setting unit constitute the drive control unit 58.

  Reference numeral 62 denotes a TFT (Thin Film Transistor) circuit formed on the glass substrate 50. The TFT circuit 62 includes a shift register, a data latch unit, and the like, a gate controller (not shown) that controls the timing of turning on / off the organic electroluminescence element 63, and a drive circuit that supplies a drive current to each organic electroluminescence element 63 (Not shown, hereinafter referred to as a pixel circuit). One pixel circuit is provided for each organic electroluminescence element 63, and is provided in parallel with the light emitting element row formed by the organic electroluminescence element 63. A drive current value for driving each organic electroluminescence element 63 is set in the pixel circuit by a source driver 61 which is a drive parameter setting unit.

  A gate controller (not shown) constituting the TFT circuit 62 is supplied with a control signal such as a power supply, a clock signal, and a line synchronization signal and binary image data from the outside of the exposure apparatus 13 via the FPC 60, and the gate controller (FIG. (Not shown) controls the lighting / extinguishing timing of each light emitting element based on these power sources and signals. The operations of the gate controller and the pixel circuit (both not shown) will be described in detail later with reference to the drawings.

  Reference numeral 64 denotes sealing glass. When the organic electroluminescence element 63 is affected by moisture, the light emission characteristics are extremely deteriorated due to shrinkage of the light emitting region over time (shrinking) and non-light emitting portions (dark spots) in the light emitting region. Sealing is necessary to block moisture. In the first embodiment, a solid sealing method in which the sealing glass 64 is attached to the glass substrate 50 via an adhesive is employed. However, the sealing region is generally sub-scanned from the light emitting element array formed by the organic electroluminescence element 63. About 2000 μm is required in the direction, and even in Example 1, 2000 μm is secured as a sealing margin.

  57 is an exposure amount sensor unit as an exposure amount detection unit in which a plurality of film-like exposure amount sensors made of amorphous silicon or the like are arranged in the main scanning direction along the end face of the glass substrate 50, and 59 is at least an amplification circuit And a processing circuit including an analog-digital conversion circuit. The exposure amount of each organic electroluminescence element 63 is measured by the exposure amount sensor unit 57. In principle, it is necessary to measure the exposure amount by individually lighting the organic electroluminescence elements 63 one by one, but the exposure amount sensor is sufficiently separated from the organic electroluminescence element 63 to be measured. In the first embodiment, the exposure amount sensor unit 57 is composed of a plurality of exposure amount sensors, since there is almost no influence of the light emission (the emitted light from the organic electroluminescence element 63 is attenuated). It is possible to simultaneously measure the exposure amount of the organic electroluminescence element 63.

  The outputs of the plurality of exposure amount sensors are input to the processing circuit 59 through wiring not shown. The processing circuit 59 is an analog / digital mixed IC chip. The output of each exposure amount sensor constituting the exposure amount sensor unit 57 is subjected to voltage conversion by the charge accumulation method in the processing circuit 59, further amplified by a predetermined amplification factor, and then converted from analog to digital. The later digital data (hereinafter referred to as exposure amount measurement data) is output to the outside of the exposure apparatus 33 via the FPC 60, the relay board 52, and the cable 56 (both see FIG. 3). As will be described in detail later, the exposure amount measurement data is received and processed by a controller CPU (not shown) mounted on the controller 41 (see FIG. 1) to generate 8-bit exposure amount correction data.

  FIG. 5 is a block diagram showing the configuration of the controller 41 in the image forming apparatus 1 according to the first embodiment of the present invention.

  Hereinafter, the operation of the controller 41 will be described with reference to FIG. 5, and the exposure amount correction will be described in more detail.

  In FIG. 5, reference numeral 80 denotes a computer. The computer 80 is connected to a network 81, and transfers image information, the number of prints, and print job information such as a print mode (for example, color / monochrome) to the controller 41 via the network 81. 82 is a network interface. The controller 41 receives the image information and print job information transferred from the computer 80 via the network interface 82, develops the image information into printable binary image data, and conversely detected by the image forming apparatus side. Error information or the like is transmitted as so-called status information to the computer 80 via the network 81.

  A controller CPU 83 controls the operation of the controller 80 based on a program stored in the ROM 84. A RAM 85 is used as a work area for the controller CPU 83, and temporarily stores image information, print job information, and the like received via the network interface 82.

  Reference numeral 86 denotes an image processing unit. The image processing unit 86 can perform printing by performing image processing (for example, image development processing based on printer language, color correction, edge correction, screen generation, etc.) on a page basis based on image information and print job information transferred from the computer 80. Binary image data is generated and stored in the image memory 65 in units of pages.

  Reference numeral 66 denotes an exposure correction data memory composed of a rewritable nonvolatile memory such as an EEPROM.

  FIG. 6 is an explanatory diagram showing the contents of the exposure correction data memory in the image forming apparatus 1 according to the first embodiment of the present invention.

  Hereinafter, the data structure and data contents in the exposure correction data memory will be described with reference to FIG.

  As shown in FIG. 6, the exposure correction data memory 66 has three areas from the first area to the third area. Each area includes 5120 8-bit data equal to the number of organic electroluminescence elements 63 (see FIG. 4) constituting the exposure apparatus 13 (see FIG. 3), and occupies a total of 15360 bytes.

  First, data DD [0] to DD [5119] stored in the first area will be described with reference to FIGS. 3 and 4 in FIG.

  The exposure apparatus 13 (see FIG. 3) already described includes a step of adjusting the exposure amount of each organic electroluminescence element 63 (see FIG. 4) constituting the exposure apparatus 13 in the manufacturing process. In this step, the exposure apparatus 13 is attached to a predetermined jig (not shown), and the organic electroluminescence element 63 is individually controlled to be turned on based on a control signal supplied from the outside of the exposure apparatus 13.

  Further, a CCD camera provided on a jig (not shown) measures the two-dimensional exposure amount distribution of each organic electroluminescence element 63 at the image plane position of the photoreceptor 8 (see FIG. 3). A jig (not shown) calculates the potential distribution of the latent image formed on the photoconductor 8 based on the exposure amount distribution, and further correlates with the toner adhesion amount based on the actual development condition (development bias value). Calculate the latent image cross section. In a jig (not shown), the driving current value for driving the organic electroluminescence element 63 is changed {as described above, the TFT circuit 62 (see FIG. 4) is connected via the source driver 61 (see FIG. 4). A current value for driving the organic electroluminescence element 63 can be set by programming an analog value in the pixel circuit to be configured. } A driving current value at which all of the latent image cross-sectional areas formed by the individual organic electroluminescence elements 63 become substantially equal, that is, a setting value for the pixel circuit (setting data for the source driver 61 from the viewpoint of control) To extract.

  Now, assuming that the light emission area of the organic electroluminescence element 63 and the light emission quantity distribution in the light emission surface are equal and normal development conditions are assumed, the above-described latent image cross-sectional area is substantially proportional to the exposure amount. Furthermore, “the amount of light emitted when the exposure time is constant” and “the amount of exposure” are synonymous, and generally the amount of light emitted from the organic electroluminescence element 63 and the drive current value (that is, the set value for the pixel circuit) are proportional. Therefore, by setting the drive current setting to all the pixel circuits to be the same and measuring the light emission amount of each organic electroluminescence element 63 once, the latent image cross-sectional area by each organic electroluminescence element 63 is made constant. It is also possible to obtain a setting value for the pixel circuit (setting data for the source driver 61 as described above) by calculation.

  In the first area of the exposure correction data memory 66, the setting data for the source driver 61 obtained in this way is stored. The number thereof is 5120 equal to the number of organic electroluminescence elements 63 constituting the exposure apparatus 13 as described above (that is, equal to the number of pixel circuits). As described above, the first area of the exposure amount correction data memory 66 stores “the set value of the source driver 61 for equalizing the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 63 in the initial state”. Yes.

  Next, data ID [0] to ID [5119] stored in the second area will be described with reference to FIGS.

  The jig acquires the data stored in the first area, and at the same time, the 8-bit exposure amount based on the output of the exposure amount sensor unit 57 (see FIG. 4) via the processing circuit 59 (see FIG. 4) of the exposure apparatus 13. Get measurement data. Thereby, “exposure amount measurement data when the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 63 in the initial state are equal” can be acquired. The 8-bit exposure amount measurement data ID [n] is stored in the second area.

  Now, the driving condition of the organic electroluminescence element 63 when acquiring ID [n] by the jig needs to be the same as that at the time of exposure amount measurement. In the first embodiment, as described later, 1 of the image forming apparatus 1 is used. A lighting period of about 30 ms in total is given by applying 350 μs, which is a line period (raster period), a plurality of times.

  In this way, data stored in the first area and the second area in the manufacturing process of the exposure apparatus 13 is acquired, and these data are written from the jig to the exposure correction data memory 66 by electrical communication means (not shown). It is.

  Next, data ND [0] to ND [5119] stored in the third area will be described with reference to FIG. 6, FIG. 4, and FIG.

  The image forming apparatus 1 according to the first embodiment of the present invention includes an exposure amount correction unit that corrects the exposure amounts of the organic electroluminescence elements 63 approximately equally based on the measurement result by the exposure amount sensor unit 57 as the exposure amount measurement unit. {Controller CPU 83 (see FIG. 5)}, and based on the output of the exposure amount correction unit, the exposure amount setting unit (also controller CPU 83) determines the exposure amount of each organic electroluminescence element 63 when performing image formation. Set. In the third area, a setting value of the exposure amount of each organic electroluminescence element 63 when performing image formation by the controller CPU 83 which is a light amount correction unit, that is, exposure amount correction data is written.

  In the image forming apparatus 1 according to the first exemplary embodiment, the organic electroluminescence element 63 included in the exposure device 13 is initialized at the time of initializing the image forming apparatus 1, starting up the image forming operation, gap between sheets, and completing the image forming operation. Measuring the exposure amount is as described above. The controller CPU 83 calculates the exposure amount measurement data measured at these points in time and the latent image sectional area formed by each organic electroluminescence element 63 in the initial state stored in the first area in the manufacturing process of the exposure apparatus 13. The set value of the source driver 61 for equalization is equal to the cross-sectional area of the latent image formed by each organic electroluminescence element 63 in the initial state stored in the second area in the manufacturing process of the exposure apparatus 13. The exposure amount correction data is generated based on the “exposure amount measurement data”.

  Hereinafter, the calculation contents of the exposure correction data by the controller CPU 83 will be described. In order to clarify the point of the present invention, first, the description will be made assuming that the exposure at the time of measuring the exposure is equal to that at the time of image formation.

  DD [n] (n is the value in the main scanning direction) stored in the first area is “the set value of the source driver 61 for equalizing the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 63 in the initial state”. ID of each organic electroluminescence element number, the same shall apply hereinafter), and “exposure amount measurement data when equalizing the cross-sectional area of the latent image formed by each organic electroluminescence element 63 in the initial state” stored in the second area [N] When the exposure amount measurement data newly measured in the initialization operation or the like is PD [n], the new exposure amount correction data ND [n] written in the third area is expressed by (Equation 1). Based on the controller CPU83.

  The calculation formula shown in (Equation 1) is a basic calculation formula for calculating exposure correction data, and should be applied when the exposure during image formation and exposure measurement is equal as described above. . In the first embodiment, the exposure amount of the organic electroluminescence element 63 at the time of light amount measurement for exposure amount correction is set smaller than the exposure amount at the time of image formation. In order to realize this, when measuring the exposure amount, DD [n] is multiplied by a constant k smaller than 1 as exposure amount correction data to be sent to the exposure device 13, and the organic electroluminescence element 63 is set based on this. Light up. For example, by multiplying k by 0.5 and multiplying the exposure amount correction data DD [n] by the pixel driver (not shown) via the source driver 61 (see FIG. 4) as described above, the organic electroluminescence element 63 can emit light with a light amount (unit: cd / m 2) that is 0.5 times that in image formation. The new exposure correction data ND [n] at this time may be generated based on (Equation 2).

  The exposure correction data ND [n] generated in this way is once written in the area 3 of the exposure correction data memory 66 (see FIG. 5). Thereafter, prior to image formation, the exposure correction data ND [n] is copied from the exposure correction data memory 66 to a predetermined area of the image memory 65 (see FIG. 5). The exposure amount correction data ND [n] copied to the image memory 65 when forming an image is temporarily stored in a buffer memory 88 (see FIG. 5), which will be described later, together with the binary image data, and is printed in the printer interface 87 (FIG. 5). The engine exposure amount measurement data is subjected to voltage conversion by the charge accumulation method in the processing circuit 59 (see FIG. 4). The charge accumulation method is effective for improving the SN ratio. However, since the output (current value) of the exposure amount sensor constituting the exposure amount sensor unit 57 (see FIG. 4) is very small, a certain amount of charge accumulation is required. Requires accumulation time. In the first embodiment, the SN ratio in the exposure measurement = 48 dB is ensured by setting the accumulation time to about 30 ms. However, if the accumulation time is 30 ms, it takes a long time to measure the exposure amount. When the exposure amount is measured one by one for 5120 organic electroluminescence elements 63 (see FIG. 4), it becomes 5120 × 30 ms = 154 seconds, which is not practical. Therefore, in the first embodiment, the exposure amount sensor constituting the exposure amount sensor unit 57 is made up of 32 film-like amorphous sensors, which are divided into two even and odd groups, and charge is accumulated simultaneously in units of groups (that is, 16 exposure amount sensors). By measuring the terminal voltage of the exposure amount sensor after charge accumulation, crosstalk between adjacent exposure amount sensors is suppressed, and the processing speed is increased. As a result, the exposure amount can be measured in 154/16 = 9.6 seconds. The configuration of the exposure amount sensor unit 57 will be described in detail later.

  Hereinafter, the description will be continued returning to FIG.

  Reference numeral 88 denotes a buffer memory. The binary image data and the exposure amount correction data stored in the image memory 65 are temporarily stored in the buffer memory 88 when transferred to the engine control unit 42. The buffer memory 88 is constituted by a so-called dual port RAM in order to absorb the difference between the transfer speed from the image memory 65 to the buffer memory 88 and the data transfer speed from the buffer memory 88 to the engine control unit 42.

  Reference numeral 87 denotes a printer interface. The binary image data and the exposure amount correction data in page units stored in the image memory 65 are transferred to the engine control unit 42 via the printer interface 87 in synchronization with the clock signal and line synchronization signal generated by the timing generation unit 67. Is done.

  FIG. 7 is a block diagram showing the configuration of the engine control unit 42 in the image forming apparatus 1 according to the first embodiment of the present invention.

  Hereinafter, the operation of the engine control unit 42 will be described in detail with reference to FIG.

  In FIG. 7, reference numeral 90 denotes a controller interface. The controller interface 90 receives exposure correction data transferred from the controller 41, binary image data in units of pages, and the like.

  An engine control CPU 91 controls an image forming operation in the image forming apparatus 1 based on a program stored in the ROM 92. A RAM 93 is used as a work area when the engine control CPU 91 operates. 94 is a so-called rewritable nonvolatile memory such as an EEPROM. The nonvolatile memory 94 stores information on the lifetime of the constituent elements such as the rotation time of the photoconductor 8 of the image forming apparatus 1 and the operation time of the fixing device 23 (see FIG. 1).

  Reference numeral 95 denotes a serial interface. Information from sensor groups such as the recording paper passage detection sensor 21 (see FIG. 1) and the recording paper trailing edge detection sensor 28 (see FIG. 1) and the output of the power supply monitoring unit 44 (see FIG. 1) are not shown. Is converted into a serial signal having a predetermined cycle and received by the serial interface 95. The serial signal received by the serial interface 95 is converted into a parallel signal and then read by the engine control CPU 91 via the bus 99.

  On the other hand, control for an actuator group 96 such as an electromagnetic clutch (not shown) for controlling the starting and stopping of the paper feed roller 18 and the drive source 38 (both see FIG. 1) and the driving force transmission to the paper feed roller 18 (see FIG. 1). Signals and control signals for the high voltage power supply control unit 97 that manages potential settings such as development bias, transfer bias, and charging potential are sent to the serial interface 95 as parallel signals. The serial interface 95 converts the parallel signal into a serial signal and outputs it to the actuator group 96 and the high voltage power supply control unit 97. As described above, in the first embodiment, sensor inputs and actuator control signals that do not need to be detected at high speed are all output via the serial interface 95. On the other hand, for example, a control signal for driving / stopping the registration roller 19 that requires a certain high speed is directly connected to the output terminal of the engine control CPU 42.

  An operation panel 98 is connected to the serial interface 95. The instruction given to the operation panel 98 by the user is recognized by the engine control CPU 91 via the serial interface 95. In the first embodiment, an operation panel is provided as an instruction input unit for inputting a user instruction. Based on the input to the operation panel, the exposure amount of the organic electroluminescence element 63 constituting the exposure apparatus 13 is measured, and exposure is performed. The amount is corrected. This instruction can of course be given from an external computer or the like via the controller 41. As a specific usage mode, for example, when the user discovers density unevenness on the printing surface when a large amount of printing is performed, the user forcibly corrects the exposure amount to ensure image quality. A case is assumed. If the image forming apparatus 1 is on standby, the user can instruct execution of forced exposure amount correction at any time, and even during image formation, the image forming apparatus 1 is shifted to offline to perform image formation. By temporarily holding it, the user can instruct execution of exposure amount correction. For such a situation where the user compulsorily corrects the amount of exposure, an immediate response is desired. For example, during non-image formation such as in the off-line state described above, all the organic electroluminescence elements 63 emit light. The amount of light is measured.

  In any case, when an exposure correction request is input from the operation panel 98 or the like as an instruction unit, the engine control CPU 91 starts driving the components of the image forming apparatus 1 as described in <Initialization Operation>. Then, a request for creating dummy image information for correcting the exposure amount is output to the controller 41. Based on this request, the controller CPU 83 mounted on the controller 41 generates dummy image information for exposure amount correction, and based on this, the organic electroluminescence element 63 constituting the exposure device 13 is controlled to be lit. At this time, the exposure amount sensor unit 57 provided in the exposure apparatus 13 described above detects the exposure amount of each organic electroluminescence element 63, and based on the detection result of the exposure amount, the individual organic electroluminescence element 63. The exposure amount is corrected so that the exposure amounts are substantially equal.

  Next, the operation for measuring the exposure amount of the organic electroluminescence element 63 will be described in detail with reference to FIGS. 1, 5 and 6 in FIG.

  As described above, the correction of the exposure amount is performed at the timing specified by the user using the operation panel 98 after the initialization operation immediately after the start of the image forming apparatus 1, before the start of printing, between sheets, after the start of printing. Therefore, a case where the exposure amount is measured at the time of initialization operation of the image forming apparatus 1 will be described. Further, the image forming apparatus 1 according to the first embodiment is configured to be capable of forming a full-color image and includes the exposure apparatuses 13Y to 13K (see FIG. 1) corresponding to four colors as described above. For the sake of simplicity, only the operation for one color will be described and described as an exposure apparatus 13. In the situation shown below, for example, it is assumed that the drive source 38 (see FIG. 1), the developing station 2 (see FIG. 2), and the like have already been activated as described in detail in <Initialization Operation>.

  In the image forming apparatus 1, the engine control unit 42 manages the image forming operation, and the exposure amount correction sequence including the exposure amount measurement is started by the engine control CPU 91 of the engine control unit 42. First, the engine control CPU 91 outputs to the controller 41 a request for creating dummy image information that is different from the regular binary image data related to image formation.

  The engine control unit 42 and the controller 41 are connected by a bidirectional serial interface (not shown), and can exchange a request command (request) and an acknowledgment (response information) with respect to each other. The dummy image information creation request issued by the engine control CPU 91 is output from the controller interface 90 to the controller 41 via the bus 99 using this bidirectional serial interface (not shown).

  Based on this request, the controller CPU 83 mounted on the controller 41 directly creates dummy image information, that is, binary image data used for exposure amount measurement in the image memory 65. Further, the controller CPU 83 stores “the source driver 61 for equalizing the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 63 in the initial state” stored in the first area (see FIG. 6) of the exposure correction data memory 66. Set value DD [n] (n: 0 to 5119) is read and multiplied by a constant k (for example, 0.5) smaller than 1 to set the exposure amount of the organic electroluminescence element 63 from that during normal image formation. Also set it low. This value is written in a predetermined area of the image memory 65. When these processes are completed, the controller CPU 83 outputs response information to the engine control unit 42 via the printer interface 87.

  The value of the constant k for setting the exposure amount of the organic electroluminescence element 63 when measuring the exposure amount is 0.5 (that is, the exposure amount when measuring the exposure amount is halved at the time of image formation). It is not limited to. The object of the present invention is to solve the problem caused by exposing the photosensitive member 8 by light emission of the organic electroluminescence element 63 when measuring the amount of exposure and making it appear, so that this object is achieved. In this case, the constant k may be set to any value. As the constant k is decreased, the amount of light emitted from the organic electroluminescence element 63 is decreased, and accordingly, the potential potential of the latent image formed on the photoconductor 8 is also decreased. Therefore, it becomes difficult to develop. However, since the value detected by the exposure amount detection sensor unit 57 is also small, it is disadvantageous in terms of the SN ratio when measuring the exposure amount. In actual application, the value of the constant k needs to be determined in consideration of “difficult to develop” and “S / N ratio when measuring exposure amount”.

  The value of the constant k is preferably changed according to the environment and situation where the image forming apparatus 1 is placed. In particular, the image forming apparatus 1 to which the electrophotographic system is applied changes the development characteristics depending on the environment (temperature, humidity), deterioration with time of the photoconductor 8, and the like, and therefore, for example, a temperature / humidity sensor (not shown) or the nonvolatile memory already described. It is desirable to change the value of k based on the information about the lifetime stored in 94. Further, since the SN ratio at the time of measurement can be substantially improved by extending the charge accumulation time by the processing circuit 59 (see FIG. 4) already described, for example, the temperature inside the image forming apparatus 1 is increased. When the number of organic electroluminescence elements 63 whose exposure is to be measured can be reduced between the sheets, the constant k can be set smaller, and the range of selection of the constant k is expanded.

  The engine control CPU 91 of the engine control unit 42 that has received the response information immediately sets a write timing for the exposure apparatus 13. That is, the engine control CPU 91 sets the timing for writing the electrostatic latent image by the exposure device 13 to a timer, which is hardware (not shown), and starts the operation of the timer as soon as response information is received (this function is originally provided with a plurality of exposure devices). This is for determining the activation timing for each color of 13. Such a precise timing setting is not necessary in the measurement of the exposure amount, and for example, 0 may be set in the timer). Each timer outputs an image data transfer request to the controller 41 when a preset time has elapsed. The controller 41 that has received the image data transfer request transfers the binary image data to the exposure device 13 in synchronization with the timing signal (clock signal, line synchronization signal, etc.) generated by the timing generator 67 via the controller interface 90. . At the same time, the “exposure amount setting value set lower than that during normal image formation” already written in the image memory 65 is also transferred to the exposure apparatus 13 in synchronization with the timing signal. Note that the exposure correction data (ND [n] already described) is the same instead of the “exposure value set lower than that during normal image formation” in normal image formation, not during exposure measurement. The light is supplied to the exposure device 13 through the transfer path.

  The binary image data transferred in synchronization with the timing signal in this manner is input to the TFT circuit 62 of the exposure apparatus 13, and at the same time, the exposure amount setting value is input to the source driver 61 of the exposure apparatus 13. The exposure device 13 controls the lighting and extinguishing of the corresponding organic electroluminescence element 63 based on the input binary image data, that is, ON / OFF information. The exposure amount of the organic electroluminescence element 63 at this time is based on the set value of the exposure amount, and emits light with a light amount lower than the exposure amount for normal image formation. At this time, the exposure amount of each organic electroluminescence element 63 is measured by an exposure amount sensor constituting the exposure amount sensor unit 57.

  FIG. 8 is an explanatory diagram showing the positional relationship between the organic electroluminescence element 63 and the exposure amount sensor constituting the exposure amount sensor unit 57 in the image forming apparatus 1 according to the first embodiment of the present invention.

  In FIG. 8, reference numerals 100a to 100e denote exposure amount sensors. Hereinafter, the process of measuring the exposure amount by the exposure amount sensor unit 57 will be described. When the exposure amount sensor is collectively shown, it is expressed as the exposure amount sensor 100.

  The organic electroluminescence elements 63 in Example 1 have a polygonal or substantially circular shape with a side of about 40 μm, and these are arranged in a line on the glass substrate 50 at a resolution of 600 dpi, that is, a 42.3 μm pitch. Is configured. The exposure amount sensor unit 57 includes 32 exposure amount sensors 100 each having a width of about 6.5 mm. The exposure amount sensor unit 57 is bonded to the end surface of the glass substrate 50 in parallel with the row formed by the organic electroluminescence elements 63. Have been placed. The distance between the light emitting element array and the exposure amount sensor unit 57 is set to 2 mm because of the necessity of sealing as described with reference to FIG.

  As shown in FIG. 8, the exposure amount sensor unit 57 is composed of a group A composed of exposure amount sensors 100a, 100b, 100c,... And a group B composed of 100d, 100e,. At the time when the exposure amount of the organic electroluminescence element 63 is measured by the exposure amount sensors 100a, 100b, and 100c of the A group, the exposure amount sensors 100d and 100e of the B group are processed by a switching circuit (not shown) constituted by TFTs. (See FIG. 7) The connection with the device is disconnected, and the exposure amount is not measured. This control is also performed based on the above-described timing signal (see FIG. 7), and is indirectly managed by the engine control CPU 91 of the engine control unit 42 that activates the process.

  The A group and the B group are alternately measured, and when the exposure amount is measured by one group, all the exposure amount sensors 100 of the corresponding group simultaneously measure the exposure amount. At this time, for example, the exposure amount of the organic electroluminescence element 63 formed at the position P1 is the exposure amount sensor 100a, and the exposure amount of the organic electroluminescence element 63 formed at the position P2 is the exposure amount sensor 100b, and the position of P3. The exposure amount of the organic electroluminescence element 63 formed in the above is measured by the exposure amount sensor 100c. In order to cause the organic electroluminescence element 63 at a specific position such as P1, P2, P3... To emit light, dummy image information corresponding to the organic electroluminescence element 63 at the position is generated by the controller 41 (see FIG. 5). The

  Now, since the exposure amount sensor 100 which comprises B group is arrange | positioned among these among P1, P2, and P3, a sufficiently big space | interval can be provided between P1 and P2 and P2 and P3. By doing so, it is possible to sufficiently reduce so-called optical crosstalk, in which the emitted light of the organic electroluminescence element 63 at the position P1 reaches the exposure amount sensors 100b and 100c and is detected.

  Thus, in measuring the exposure amount, the positions of the organic electroluminescence elements 63 that emit light are discrete. In the electrophotographic method, a latent image area that is continuous in area (especially in the main scanning direction) is easy to be developed, but when a small latent image exists in isolation, the action of electric lines of force is small and development is difficult. Have. In the first embodiment, the arrangement of the latent image is devised in this way to prevent the toner from adhering to the photoconductor 8 when measuring the exposure amount.

  Hereinafter, the description will be continued returning to FIG.

  As described above, the lighting of the organic electroluminescence element 63 is controlled, and the exposure amount is measured by the exposure amount sensor unit 57. The output (analog current value) of the exposure amount sensor unit 57 is converted into a voltage by the charge accumulation method in the processing circuit 59, amplified with a predetermined amplification factor, and then subjected to analog-digital conversion to obtain 8-bit exposure amount measurement data. It is output from the processing circuit 59 as (digital data).

  The exposure measurement data output from the processing circuit 59 is transferred from the engine control unit 42 to the controller 41 via the controller interface 90 and received by the controller CPU 83 of the controller 41. As described with reference to FIGS. 5 and 6, the controller CPU 83 generates light amount correction data ND [n] using PD [n] in (Equation 2) as described above.

  FIG. 9 is a circuit diagram of the exposure device 13 in the image forming apparatus 1 according to the first embodiment of the present invention.

  Hereinafter, the lighting control by the TFT circuit 62 and the source driver 61 will be described in more detail with reference to FIG.

  The TFT circuit 62 is roughly divided into a pixel circuit 69 and a gate controller 68. One pixel circuit 69 is provided for each organic electroluminescence element 63, and N groups are provided on the glass substrate 50 with the M pixels of the organic electroluminescence element 63 as one group.

  In the first embodiment, one group is 8 pixels (that is, M = 8), and this group is 640. Therefore, the total number of pixels is 8 × 640 = 5120 pixels. Each pixel circuit 69 supplies a current to the organic electroluminescence element 63 and drives it, and a current value supplied by the driver when controlling the lighting of the organic electroluminescence element 63 (that is, a drive current value of the organic electroluminescence element 63). ) Is stored in a capacitor included therein, and the organic electroluminescence element 63 can be driven at a constant current according to a drive current value programmed in advance at a predetermined timing.

  The gate controller 68 includes a shift register that sequentially shifts input binary image data, a latch unit that is provided in parallel with the shift register and collectively holds the input after a predetermined number of pixels have been input to the shift register, It consists of a control part which controls these operation timings (both not shown). The gate controller 68 is supplied with binary image data from the controller 41 (image information converted by the controller 41 when forming an image, and dummy image information converted by the controller 41 when measuring an exposure amount). Based on the ON / OFF information, SCAN_A and SCAN_B signals are output, thereby controlling the timing of turning on / off the organic electroluminescence element 63 connected to the pixel circuit 69 and the timing of the current program period for setting the drive current. To do.

  On the other hand, the source driver 61 has a number of D / A converters 72 (640 in the first embodiment) corresponding to the number N of groups of the organic electroluminescence elements 63 inside. The source driver 61 supplies 8-bit exposure correction data (ND [n] shown in FIG. 6 at the time of image formation, and DD [n] shown in FIG. 6 at the time of image formation to a constant k smaller than 1 supplied via the FPC 60. The drive current for each organic electroluminescence element 63 is set based on the value obtained by multiplying With this configuration, the exposure amount of each organic electroluminescence element 63 is uniformly controlled by the light quantity correction data ND [n] already described at the time of image formation, and at the time of exposure amount measurement, the exposure amount at the time of normal image formation. The exposure amount of the organic electroluminescence element 63 is controlled with a low exposure amount.

  FIG. 10 is an explanatory diagram showing a current program period and a lighting period of the organic electroluminescence element 63 according to the exposure device 13 in the image forming apparatus 1 of Embodiment 1 of the present invention.

  Hereinafter, the lighting control of the first embodiment will be described in more detail with reference to FIG. In order to simplify the description, one pixel group (for example, “pixel number in the main scanning direction” = 1 to 8 in FIG. 10) will be described.

  In the first embodiment, one line period (raster period) of the exposure apparatus 13 is set to 350 μs, and 1/8 (43.77 μs) of the one line period is driven to the capacitor formed in the current program unit 71. It is used as the program period for setting the current value.

  First, the gate controller 68 (see FIG. 9) sets the program period by turning on the SCAN_A signal and turning off the SCAN_B signal for the pixel of pixel number = 1. During the program period, 8-bit exposure correction data is supplied to the D / A converter 72 built in the source driver 61 (see FIG. 9), and the supplied digital data is converted into an analog level signal obtained by D / A conversion. The capacitor of the current program unit 71 (see FIG. 9) is charged. This program period is executed regardless of ON / OFF of the binary image data input to the gate controller 68. As a result, the capacitor formed in the current program unit 71 has 8-bit exposure correction data (ND [n] shown in FIG. 6 at the time of image formation, and DD [n] shown in FIG. An analog value based on a value obtained by multiplying a small constant k) is written every time one line period. That is, the accumulated charge of the capacitor formed in the current program unit 71 is always refreshed, and the driving current of the organic electroluminescence element 63 determined based on this is always kept constant.

  When the program period is completed, the gate controller 68 (see FIG. 9) immediately sets the lighting period by switching the SCAN_A signal to OFF and the SCAN_B signal to ON. As already described, binary image data is supplied to the gate controller 68 (see FIG. 9) according to the time of image formation and exposure amount measurement. If the image data is OFF even during the lighting period, the organic electro The luminescence element 63 is not lit. On the other hand, when the image data is ON, the organic electroluminescence element 63 continues to be lit for the remaining 306.25 μs (350 μs−43.75 μs) (actually there is a switching time of the control signal, so the light emission time is slightly shortened). ). As already described, in Example 1, when the exposure amount of the organic electroluminescence element 63 is measured, a measurement period of 30 ms is assumed. Therefore, the number of times of lighting at the time of exposure amount measurement is, for example, 100 times (that is, 100 lines). As described above, the controller 41 generates dummy image information.

  On the other hand, when the program period for the pixel circuit 69 (see FIG. 9) with the pixel number = 1 shown in FIG. 10 ends, the gate controller 68 (see FIG. 9) immediately applies to the pixel circuit 69 with pixel number = 8 (see FIG. 9). Sets the current program period. Thereafter, similar to the procedure for the pixel circuit of pixel number 1, as soon as the program period for the pixel circuit of pixel number 8 is completed, the process proceeds to the lighting period of the organic electroluminescence element 63 (see FIG. 9) of the pixel number.

  In this way, the gate controller 68 (see FIG. 9) sets the pixel number in the main scanning direction = “1 → 8 → 2 → 7 → 3 → 6 → 4 → 5 → 1... Will be set. By adopting such a lighting order, the lighting timing of the nearest pixel is adjacent in time between adjacent pixel groups, so that the image step at the time of forming one line can be made inconspicuous.

  Here, the value set in the pixel circuit 69 (see FIG. 9) in the current program period is, for example, 8-bit exposure correction data as described above. Since the organic electroluminescence element 63 (see FIG. 9) is formed by a coating process such as spin coating, the adjacent pixel correlation is extremely high. Due to this effect, the emission luminance of the organic electroluminescence element 63 (see FIG. 9) in the vicinity of the specific organic electroluminescence element 63 (see FIG. 9) becomes almost the same. Accordingly, since the correlation between the exposure amount correction data for the adjacent organic electroluminescence elements 63 (see FIG. 9) is very high, for example, the exposure amount correction data for pixel number = 1 and the exposure amount correction data for pixel number = 8 are greatly different. There is no.

  In the current program period controlled by the gate controller 68 (see FIG. 9), a current value according to the exposure amount correction data is supplied to the pixel circuit 69 (see FIG. 9), and the pixel circuit 69 (see FIG. 9) The capacitor is charged with a so-called constant current source, and the time required for charging is (Equation 3).

  According to (Equation 3), the charging time is proportional to the capacitance, and if the capacitance C increases due to the increase in the wiring capacitance accompanying wiring routing, the charging time increases. In Example 1, in order to dispose the source driver on the extended line of the light emitting element array and at the end in the long side direction of the glass substrate 50, in the pixel group farthest from the source driver 61 (see FIG. 9), Normally, there is a concern about charging delay due to wiring capacity.

  However, in the first embodiment, the exposure amount correction data is supplied by the source driver 61 (see FIG. 9), and the value of the exposure amount correction data is high in one pixel group as described above. Within the same pixel group, V in (Equation 3) hardly changes. After all, in the current programming process, the difference in V between sequentially selected pixel numbers dominates the charging time, but the difference in V between originally selected pixel numbers is very small, so the charging time is very short. It becomes. Therefore, the shortage of the current program period due to the increase in the wiring length from the source driver 61 (see FIG. 9) has almost no problem in the first embodiment, and the source driver 61 has been described so far. The distance between the pixel circuit 69 (see FIG. 9) and the pixel circuit 69 (see FIG. 9) can be greatly separated.

  This situation is greatly different from a display that uses a current programming method to set a drive current for each pixel unit and reproduces multiple gradations such as 64 gradations and 256 gradations for each pixel unit. It can be said that this is a merit unique to the exposure apparatus 13 that can control lighting / extinction based on image data and set a drive current by a current programming method based on multi-value exposure amount correction data.

  In the first embodiment, the description has been made on the assumption that the exposure time of the organic electroluminescence element 63 is controlled by changing the current value while keeping the lighting time of the organic electroluminescence element 63 constituting the exposure apparatus 13 constant. However, the present invention can be easily applied to a so-called PWM method in which the driving current value of a light emitting element such as the organic electroluminescence element 63 is fixedly set and the exposure time of the light emitting element is controlled by changing the lighting time. In this case, the contents of the first area described with reference to FIG. 6 may be replaced with “setting value of driving time for equalizing latent image cross-sectional areas”.

(Example 2)
Hereinafter, the second embodiment of the present invention will be described. The overall configuration of the image forming apparatus 1 according to the second embodiment is almost the same as that of the first embodiment except for the peripheral portion of the developing station 2. Is omitted.

  FIG. 11 is a configuration diagram illustrating the periphery of the developing station 2 of the image forming apparatus according to the second exemplary embodiment of the present invention.

  FIG. 12A is an explanatory diagram showing the state of the exposure device 13 during image formation in the image forming apparatus 1 according to the second embodiment of the present invention, and FIG. 12B shows the image forming apparatus 1 according to the second embodiment of the present invention. It is explanatory drawing which shows the state of the exposure apparatus 13 at the time of light quantity measurement.

  Hereinafter, the configuration of the image forming apparatus 1 according to the second embodiment of the present invention will be described with reference to FIGS. 11, 12 (a), and 12 (b) together with FIG. 1.

  11, 12 (a), and 12 (b), 45 is an image formation suppression unit, and light emitted from the organic electroluminescence element formed on the surface A of the substrate 50 constituting the exposure apparatus 13 is Irradiation to the photoreceptor 8 is suppressed. The image formation suppression unit 45 includes a light blocking member 46 and a displacement member 47 that displaces the light blocking member 46.

  As described above, in the second embodiment, the image formation suppressing unit 45 is disposed so as to be displaceable between the exposure unit (exposure device 13) and the photosensitive member 8, and light that blocks light emitted from the exposure unit (exposure device 13). The blocking member 46 is used.

  The light blocking member 46 is a plate-shaped member made of, for example, resin, and a black film is attached to one end portion thereof, and the film blocks light emitted from the exposure device 13. In the second embodiment, the light blocking member 46 is composed of a plate-like member and a black film, but it may be integrally formed. The film for blocking light is not necessarily limited to black, and any film can be used as long as it can physically block light in the emission wavelength region of the organic electroluminescence element 63.

  The displacement member 47 is, for example, a metal shaft, and its rotation axis is configured to be shifted from the center of the metal shaft. The displacement member 47 is supported in a housing (not shown) of the image forming apparatus 1 (see FIG. 1) in parallel with the exposure device 13, the photosensitive member 8, and the like, and its end is from the drive source 38 (see FIG. 1). The motive power is transmitted, and the member is rotated in the direction D8 in units of half a circle by a member such as an electromagnetic clutch (not shown). By rotating the displacement member 47 in the direction D8, the light blocking member 46 is displaced in the direction D9 or the direction D10.

  As shown in FIG. 12A, the displacement member 47 supports the light blocking member 46 below (direction D9 side) during image formation, and is emitted from the organic electroluminescence element 63 formed on the substrate 50. The light guided by the lens array 51 reaches the photoconductor 8 without being blocked by the light blocking member 46 and forms a latent image on the photoconductor 8.

  On the other hand, as shown in FIG. 12B, at the time of light quantity measurement, the light blocking member 46 is moved upward (direction D10) by rotating the displacement member 47 halfway in the direction D8 from the state shown in FIG. ) And guided by the lens array 51 is blocked by the light blocking member 46 and does not reach the photosensitive member 8. As will be described later, the rotation of the displacement member 47 is controlled by the engine control CPU 91.

  FIG. 13 is a block diagram showing the configuration of the engine control unit 42 in the image forming apparatus 1 according to the second embodiment of the present invention.

  Hereinafter, the description will be continued using FIG.

  In the image forming apparatus 1, the engine control unit 42 manages the image forming operation, and the exposure amount correction sequence including the exposure amount measurement is started by the engine control CPU 91 of the engine control unit 42. First, the engine control CPU 91 outputs to the controller 41 a request for creating dummy image information that is different from the regular binary image data related to image formation.

  The engine control unit 42 and the controller 41 are connected by a bidirectional serial interface (not shown), and can exchange a request command (request) and an acknowledgment (response information) with respect to each other. The dummy image information creation request issued by the engine control CPU 91 is output from the controller interface 90 to the controller 41 via the bus 99 using this bidirectional serial interface (not shown).

  Based on this request, the controller CPU 83 mounted on the controller 41 directly creates dummy image information, that is, binary image data used for exposure amount measurement in the image memory 65. Further, the controller CPU 83 stores “the source driver 61 for equalizing the cross-sectional areas of the latent images formed by the individual organic electroluminescence elements 63 in the initial state” stored in the first area (see FIG. 6) of the exposure correction data memory 66. ”DD [n] (n: 0 to 5119) is read, and the exposure amount of the organic electroluminescence element 63 is set to the same value as in normal image formation. This value is written in a predetermined area of the image memory 65. When these processes are completed, the controller CPU 83 outputs response information to the engine control unit 42 via the printer interface 87.

  In Example 1, at the time of measuring the exposure amount, the light emission amount of the organic electroluminescence element 63 is set lower than that at the time of image formation (the value of the constant k is set smaller than 1 as shown in (Expression 2)). However, since the light blocking member 46 described above is provided in the second embodiment, it is not necessary to intentionally reduce the amount of light emitted from the organic electroluminescent element 63. The setting of the organic electroluminescent element 63 is as shown in (Equation 1). What is necessary is just to determine the emitted light quantity.

  Further, since the light emitted from the exposure device 13 is blocked between the lens array 51 and the photoconductor 8, the value of the constant k is set to be larger than 1, and the organic electroluminescence element 63 is measured when measuring the amount of emitted light. The amount of emitted light may be set larger than that of the first embodiment and may be set larger than the amount of emitted light during image formation. By doing so, the amount of light incident on the light amount sensor unit 57 (see FIG. 4) increases, which is advantageous in terms of light receiving sensitivity, and it is possible to improve the S / N ratio in light amount detection. .

  When the preparation for causing the organic electroluminescence element 63 to emit light is completed, the CPU 91 rotates the displacement member 47 forming one of the actuator groups 96 in the direction D8 via the serial interface 95, and displaces the light blocking member 46 in the direction D10. The black film attached to the light quantity blocking member 46 is disposed between the lens array 51 and the photoconductor 8. As a result, the optical path of the light emitted from the exposure device 13 is blocked, and a latent image resulting from the light amount measurement is not formed on the photosensitive member 8.

  That is, in the second embodiment, the light blocking member 46 is configured by a mechanically displaced shutter.

  In this state, the organic electroluminescence element 63 is caused to emit light according to the procedure described in the first embodiment, and the light emission quantity of each organic electroluminescence element 63 is measured by the light quantity sensor unit 57 (see FIG. 4). At this time, since no latent image is formed on the photoconductor 8, a toner image is not formed on the photoconductor 8 in the subsequent development process. The situation of being polluted by is prevented.

  When the measurement of the amount of emitted light is completed, the engine control CPU 91 rotates the displacement member 47 once again in the direction D8 through the serial interface 95, displaces the light blocking member 46 in the direction D9, and the light emitted from the exposure device 13 is emitted. The photosensitive member 8 is exposed to return to a state where a latent image can be formed, that is, the state shown in FIG.

  This operation can be performed during the above-described period, such as when the image forming apparatus 1 is initialized, an inter-paper period when an image forming operation is performed over a plurality of pages, or a period based on a user instruction. Needless to say.

  Thus, Example 2 has an exposure unit (exposure device 13) provided with a light-emitting element array in which a plurality of organic electroluminescence elements 63 are formed in a row, and the image carrier (photoconductor 8) is provided by this exposure unit. Is an image forming apparatus that forms an image by exposing the light, and an exposure amount measuring unit (exposure amount sensor unit shown in FIG. 4) that measures the amount of light emitted from the organic electroluminescence element 63, and an exposure amount measuring unit When the amount of light emitted from the organic electroluminescence element 63 is measured, the image forming suppression unit 45 is configured to suppress the formation of an image on the image carrier (photosensitive member 8).

  The image forming apparatus 1 according to the second embodiment includes the photoconductor 8 and the image formation suppressing unit 45 is configured to suppress the formation of a latent image on the photoconductor 8 by the exposure unit (exposure device 13). ing.

  As described above, in the second embodiment, the image formation suppression unit 45 is configured as a displaceable shutter, but the image formation suppression unit 45 may be fixedly disposed between the lens array 51 and the photoconductor 8. . In this case, the configuration of the image formation suppression unit 45 is obtained by removing, for example, the displacement member 47 from that shown in FIG. In this case, it is desirable to employ a shutter capable of electrically controlling light transmittance, such as a liquid crystal shutter (not shown), for example, as the black film for blocking the optical path described above.

  When the image formation suppression unit 45 is configured by a liquid crystal shutter, a liquid crystal shutter (not shown) may be built in the exposure apparatus 13 and disposed in a space between the lens array 51 and the substrate 50, for example. The substrate 50 is made of a material having high smoothness, such as glass, and the surface state of the surface opposite to the surface A is also extremely smooth. Therefore, the liquid crystal shutter or the like is placed along the substrate 50 with high positional accuracy. Can be arranged. Further, when such a configuration is adopted, it is not necessary to arrange a structure outside the light emitting surface of the lens array 51, and therefore the size of the exposure device 13 can be made smaller.

(Example 3)
Hereinafter, the third embodiment of the present invention will be described. The overall configuration of the image forming apparatus 1 according to the third embodiment is almost the same as that of the first embodiment except for the peripheral portion of the developing station. Omitted. Further, the control of the image formation suppression unit 45 is not substantially different from that described with reference to FIG.

  FIG. 14A is an explanatory diagram showing the state of the exposure device 13 during image formation in the image forming apparatus according to the third embodiment of the present invention, and FIG. 14B shows light amount measurement in the image forming apparatus according to the third embodiment of the present invention. It is explanatory drawing which shows the state of the exposure apparatus 13 at the time.

  Hereinafter, the configuration and operation of the image formation suppressing unit 45 in the image forming apparatus 1 according to the third embodiment of the present invention will be described with reference to FIGS. 14 (a) and 14 (b).

  14A and 14B, reference numeral 48 denotes an optical path length adjusting member that changes the optical path length between the exposure unit (exposure device 13) and the photosensitive member 8. In the third embodiment, the optical path length adjusting member 48 includes The image formation suppressing unit 45 is configured as it is.

  In the third embodiment, the exposure apparatus 13 is supported so as to be rotatable within a predetermined range with the support shaft 49 as a rotation center. The optical path length adjusting member 48 is made of, for example, a metal shaft. The rotation axis is configured to be shifted from the center of the metal shaft. The optical path length adjusting member 48 is supported in a housing (not shown) of the image forming apparatus 1 (see FIG. 1) in parallel with the exposure device 13, the photosensitive member 8, and the like. The power is transmitted from (see), and is rotated in the direction D8 in units of half a circle by a member such as an electromagnetic clutch (not shown). The exposure apparatus 13 is always pressed against the optical path length adjustment member 48 by a biasing means such as a spring (not shown). By rotating the optical path length adjustment member 48 in the direction D8, the exposure apparatus 13 on the lens array 51 side is exposed. The end portion is displaced in the direction D11 or the direction D12.

  As shown in FIG. 14A, the optical path length adjusting member 48 supports the exposure device 13 upward (direction D11 side) during image formation, and is emitted from the organic electroluminescence element 63 formed on the substrate 50. The light guided by the lens array 51 reaches the photoconductor 8 arranged in a predetermined positional relationship, and forms a latent image on the photoconductor 8.

  On the other hand, as shown in FIG. 14B, the optical path length adjusting member 48 rotates halfway in the direction D8 from the state shown in FIG. 14A during the light quantity measurement, and the exposure device 13 moves downward (direction D12). Displace. That is, in the third embodiment, the optical path length is adjusted by changing the angle formed by the optical axis of the light emitted from the exposure device 13 and the photoconductor 8 to suppress the formation of a latent image on the photoconductor 8.

  As described above, in the third embodiment, the light guided by the lens array 51 reaches the photosensitive member 8, but the distance between the lens array 51 and the photosensitive member 8 at the time of measuring the amount of light is compared with that in FIG. Adjusted longer.

  As already described, the lens array 51 is formed by arranging rod lenses (not shown) made of plastic or glass in a row, but one organic electroluminescence element 63 formed on the substrate 50 is formed. Since the emitted light is emitted in all directions, as a result, it passes through a plurality of rod lenses and forms an image on the photosensitive member 8. Therefore, at a regular focal length, the light emitted from each organic electroluminescence element 63 forms an image on the photoconductor 8 as a single light spot. However, when the focal length is longer (or shorter) than the regular distance, The light emitted from the organic electroluminescence element 63 does not form a single light spot. That is, the image transmitted by each of the plurality of rod lenses is separated into a plurality of light spots without focusing on one point.

  As already described, since the light amounts of the adjacent organic electroluminescence elements 63 are not measured simultaneously in the light amount measurement, the integrated effect is not generated by overlapping the plurality of separated light spots. The exposure amount for exposing the body 8 can be greatly reduced.

  In the second embodiment, the rotation shaft 49 of the exposure apparatus 13 is set in the vicinity of the end of the exposure apparatus 13, but it may be arranged at the center of the exposure apparatus 13 as indicated by 49a. . In this way, the position of the central axis 49 may be set to an appropriate place within a range that does not break the consistency of unit arrangement in the image forming apparatus 1.

Example 4
Hereinafter, the fourth embodiment of the present invention will be described. The overall configuration of the image forming apparatus 1 according to the fourth embodiment is almost the same as that of the first embodiment except for the peripheral portion of the developing station. Omitted. Further, the control of the image formation suppression unit 45 is not substantially different from that described with reference to FIG.

  FIG. 15A is an explanatory diagram showing the state of the exposure device 13 during image formation in the image forming apparatus according to the fourth embodiment of the present invention, and FIG. 15B is a light amount measurement in the image forming apparatus according to the fourth embodiment of the present invention. It is explanatory drawing which shows the state of the exposure apparatus 13 at the time.

  Hereinafter, the configuration and operation of the image formation suppressing unit 45 in the image forming apparatus 1 according to the fourth embodiment of the present invention will be described with reference to FIGS. 15A and 15B.

  In FIGS. 15A and 15B, reference numeral 48 denotes an optical path length adjusting member that changes the optical path length between the exposure unit (exposure device 13) and the photosensitive member 8. In the fourth embodiment, the optical path length adjusting member 48 includes The image formation suppressing unit 45 is configured as it is. Reference numeral 110 denotes a protrusion member provided in the exposure apparatus 13, and reference numeral 111 denotes an urging member composed of, for example, a spring. The optical path length adjusting member 48 and the biasing member 111 are disposed at positions facing each other with the protruding member 110 interposed therebetween.

  The optical path length adjusting member 48 is made of, for example, a metal shaft. The rotation axis is configured to be shifted from the center of the metal shaft. The optical path length adjusting member 48 is supported in a housing (not shown) of the image forming apparatus 1 (see FIG. 1) in parallel with the exposure device 13, the photosensitive member 8, and the like. The power is transmitted from (see), and is rotated in the direction D8 in units of half a circle by a member such as an electromagnetic clutch (not shown). Further, the projection member 110 fixed to the exposure apparatus 13 is always pressed against the optical path length adjusting member 48 by the biasing member 111, and the exposure apparatus 13 is rotated in the direction D13 by rotating the optical path length adjusting member 48 in the direction D8. Or, it is displaced in the direction D14.

  As shown in FIG. 15A, the optical path length adjusting member 48 supports the exposure device 13 on the left side (direction D13 side) during image formation, and from the organic electroluminescence element 63 formed on the substrate 50. The light emitted and guided by the lens array 51 reaches the photoconductor 8 arranged in a predetermined positional relationship, and forms a latent image on the photoconductor 8.

  On the other hand, as shown in FIG. 15B, the optical path length adjusting member 48 rotates halfway in the direction D8 from the state shown in FIG. 15A during the light quantity measurement, and the exposure apparatus 13 moves to the right (direction D14). It is displaced to. That is, in the fourth embodiment, the optical path length adjusting member 48 is configured to change the distance between the exposure device 13 and the photoconductor 8 in the optical axis direction of the light emitted from the exposure unit (exposure device 13). . As a result, light emitted from the exposure device 13 does not form an image on the photoconductor 8 with a simple configuration, and thus it is possible to suppress the formation of a latent image on the photoconductor 8.

  As described above, in the fourth embodiment, the light guided by the lens array 51 reaches the photoconductor 8, but the distance between the lens array 51 and the photoconductor 8 at the time of measuring the amount of light is compared with that in FIG. Adjusted longer.

  Thus, by increasing the distance between the lens array 51 and the photoconductor during light quantity measurement, the light emitted from one organic electroluminescence element 63 is a single light for the same reason as described in the third embodiment. No light spot is formed. That is, the image transmitted by each of the plurality of rod lenses is separated into a plurality of light spots without focusing on one point.

  As already described, since the light amounts of the adjacent organic electroluminescence elements 63 are not measured simultaneously in the light amount measurement, the integrated effect is not generated by overlapping the plurality of separated light spots. The exposure amount for exposing the body 8 can be greatly reduced.

  As described above, the configuration and operation according to the present invention have been described using the first to fourth embodiments. In these embodiments, a so-called tandem color image in which an image is formed using a plurality of developing stations. Although the description has focused on the forming apparatus, it is needless to say that the present invention can be easily applied to a monochrome image forming apparatus having a single photoconductor.

  Further, the present invention can be easily applied to an image forming apparatus in which a single color image is formed on a single photoconductor a plurality of times and a color image is synthesized using an intermediate medium such as an intermediate transfer member. .

  Also, depending on the exposure apparatus, there are a plurality of light emitting element arrays composed of organic electroluminescence elements, etc., and a latent image is formed by performing multiple exposures at substantially the same position with respect to the rotation direction of the photosensitive member. Is also known. Even in such an exposure apparatus, it is possible to apply the technical idea of the present invention by setting the exposure amount and the PWM time so that a latent image formed by multiple exposures does not contribute to development. Become. In such an exposure apparatus, a single light emitting element array does not form a latent image that contributes to development. Therefore, for example, a sequence in which the exposure amount is measured in units of columns between sheets can be considered.

  In Example 1 described above, the exposure amount of the organic electroluminescence element 63 is measured using the exposure amount sensor unit disposed on the end surface of the glass substrate 50 of the exposure apparatus 13, but the technical idea of the present invention is based on this. It is not limited. Since the light transmittance of, for example, low-temperature polysilicon that can constitute the TFT circuit 62 is relatively high, individual organic electroluminescence can be obtained even in the so-called bottom emission configuration in which exposure light is extracted from the glass substrate 50 side described in the first embodiment. An exposure amount sensor corresponding to each organic electroluminescence element 63 can be embedded in the element 63. In this case, the exposure amount sensor may be formed, for example, on the entire surface directly below the light emitting surface of each organic electroluminescence element 63 or may be formed corresponding to a part thereof.

  As described above, the image forming apparatus to which the electrophotographic method is applied has been described in the first embodiment, but the present invention is not limited to the electrophotographic method. Since an RGB light source can be easily realized by an organic electroluminescence element, for example, a plurality of exposure apparatuses each having an R light source, a G light source, and a B light source are arranged as exposure light sources, and photographic paper is directly applied based on image data of each RGB color. Needless to say, the present invention can also be easily applied to an image forming apparatus that exposes the light.

  As described above, the image forming apparatus according to the present invention can prevent waste of toner, particularly in an electrophotographic apparatus, and can effectively prevent contamination by toner on the back surface of recording paper. It can be used for facsimile machines, photo printers, and the like.

1 is a configuration diagram of an image forming apparatus according to a first exemplary embodiment of the present invention. 1 is a configuration diagram showing the periphery of a developing station in an image forming apparatus according to Embodiment 1 of the present invention. 1 is a configuration diagram of an exposure apparatus in an image forming apparatus according to Embodiment 1 of the present invention. (A) Top view of the glass substrate which concerns on the exposure apparatus in the image forming apparatus of Example 1 of this invention, (b) The principal part enlarged view. 1 is a block configuration diagram showing a configuration of a controller in an image forming apparatus according to Embodiment 1 of the present invention. Explanatory drawing which shows the content of the exposure amount correction data memory in the image forming apparatus of Example 1 of this invention. 1 is a block configuration diagram showing a configuration of an engine control unit in an image forming apparatus according to Embodiment 1 of the present invention. Explanatory drawing which shows the positional relationship of the exposure sensor which comprises the organic electroluminescent element and exposure dose sensor unit in the image forming apparatus of Example 1 of this invention. 1 is a circuit diagram of an exposure apparatus in an image forming apparatus according to Embodiment 1 of the present invention. Explanatory drawing which shows the electric current program period concerning the exposure apparatus in the image forming apparatus of Example 1 of this invention, and the lighting period of an organic electroluminescent element. FIG. 6 is a configuration diagram illustrating the periphery of a developing station of an image forming apparatus according to a second exemplary embodiment of the present invention. (A) Explanatory drawing showing the state of the exposure apparatus at the time of image formation in the image forming apparatus of Example 2 of the present invention, (b) State of the exposure apparatus at the time of light quantity measurement in the image forming apparatus of Example 2 of the present invention. Illustration showing FIG. 5 is a block configuration diagram illustrating a configuration of an engine control unit in an image forming apparatus according to a second exemplary embodiment of the present invention. (A) Explanatory drawing which shows the state of the exposure apparatus at the time of image formation in the image forming apparatus of Example 3 of this invention, (b) The state of the exposure apparatus at the time of light quantity measurement in the image forming apparatus of Example 3 of this invention. Illustration showing (A) Explanatory drawing which shows the state of the exposure apparatus at the time of image formation in the image forming apparatus of Example 4 of this invention, (b) The state of the exposure apparatus at the time of light quantity measurement in the image forming apparatus of Example 4 of this invention. Illustration showing Configuration diagram showing peripheral configuration of developing station in conventional image forming apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2, 2Y, 2M, 2C, 2K Developing station 3 Recording paper 4 Paper feed tray 5 Recording paper conveyance path 6 Developer 8, 8Y, 8M, 8C, 8K Photoconductor 10 Developing sleeve 13, 13Y, 13M, 13C, 13K Exposure device 19 Registration roller 20 Pinch roller 21 Recording paper passage detection sensor 41 Controller 42 Engine control unit 43 Power supply unit 45 Image formation suppression unit 46 Light blocking member 47 Displacement member 48 Optical path length adjustment member 49, 49a Support shaft 50 Glass Substrate 51 Lens array 57 Exposure amount sensor unit 59 Processing circuit 61 Source driver 62 TFT circuit 63 Organic electroluminescence element 64 Sealing glass 65 Image memory 66 Exposure amount correction data memory 67 Timing generation unit 68 Gate controller 69 Pixel circuit 7 Driver unit 71 the current program portion 72 D / A converter 80 computer 83 controller CPU
87 Printer interface 90 Controller interface 91 Engine control CPU
98 Operation panel 100, 100a, 100b, 100c, 100d, 100e Exposure amount sensor 110 Protruding member 111 Energizing member 152 Developing station 153 Recording paper 155 Recording paper conveyance path 156 Developer 158 Photoconductor 160 Developing sleeve 163 Exposure device 166 Transfer roller

Claims (19)

An image forming apparatus having an exposure unit provided with a light emitting element, and performing image formation by exposing the image carrier by the exposure unit, the exposure amount setting unit for setting an exposure amount of the light emitting element, and a light emitting element An exposure amount measuring unit for measuring an exposure amount, wherein the exposure amount setting unit sets the exposure amount of the light emitting element when measuring the exposure amount of the light emitting element to be lower than the exposure amount at the time of image formation. An image forming apparatus. An image forming apparatus comprising: a photoconductor as an image carrier on which a latent image is formed by exposure of the exposure unit; and a developing unit that develops and visualizes the latent image formed on the photoconductor. An exposure amount setting unit that sets an exposure amount of the light emitting element; and an exposure amount measurement unit that measures the exposure amount of the light emitting element. The exposure amount setting unit emits light when measuring the exposure amount of the light emitting element. 2. The image forming apparatus according to claim 1, wherein an exposure amount of the element is set lower than an exposure amount at which a latent image formed on the photosensitive member is developed. 3. The bias potential applied to the developing unit is set to OFF with respect to the area of the photoreceptor exposed during a measurement period for measuring the exposure amount of the light emitting element. Image forming apparatus. The image forming apparatus according to claim 1, wherein the exposure unit includes a light emitting element array in which a plurality of light emitting elements are formed in a row. Based on the measurement result by the exposure amount measurement unit, the exposure amount correction unit corrects each exposure amount of the light emitting elements substantially equally. Based on the output of the exposure amount correction unit, the exposure amount setting unit The image forming apparatus according to claim 4, wherein an exposure amount of each light emitting element when forming is set. In the image formation over a plurality of pages, when the exposure amount of the light emitting element is measured in a period corresponding to each page, the exposure amount of some of the light emitting elements provided in the exposure unit is measured. The image forming apparatus according to claim 4, wherein the image forming apparatus is configured as described above. The image forming apparatus according to claim 4, wherein the light emitting element is an organic electroluminescence element. The image forming apparatus according to claim 1, wherein the exposure amount of the light emitting element is measured by the exposure amount measurement unit during non-image formation. The image forming apparatus according to claim 8, wherein when performing image formation over a plurality of pages, an exposure amount of the light emitting element is measured in a period corresponding to each page. 9. The image forming apparatus according to claim 8, further comprising an instruction input unit for inputting a user instruction, and measuring an exposure amount of the light emitting element based on an input to the instruction input unit. An image forming apparatus having an exposure portion provided with a light emitting element row in which a plurality of organic electroluminescence elements are formed in a row, and performing image formation by exposing an image carrier by the exposure portion, wherein the organic electroluminescence An exposure amount measurement unit that measures the light emission amount of light emitted from the element, and suppresses the formation of an image on the image carrier when the light emission amount of the organic electroluminescence element is measured by the exposure amount measurement unit. An image forming apparatus comprising: an image formation suppressing unit that performs the operation. 12. The image according to claim 11, wherein the image carrier is a photoconductor, and the image formation suppression unit is configured to suppress a latent image from being formed on the photoconductor by the exposure unit. Forming equipment. 13. The image forming suppression unit is configured by a light blocking member that is displaceably disposed between the exposure unit and the photosensitive member and blocks light emitted from the exposure unit. Image forming apparatus. The image forming apparatus according to claim 13, wherein the light blocking member includes a mechanically displaced shutter. The image forming apparatus according to claim 13, wherein the light blocking member includes a shutter that electrically controls light transmittance. 13. The image forming apparatus according to claim 12, wherein the image formation suppressing unit is configured by an optical path length adjusting member that changes an optical path length between the exposure unit and the photosensitive member. The image forming apparatus according to claim 16, wherein the optical path length adjusting member is configured to change a distance between the exposure unit and the photoconductor in an optical axis direction of light emitted from the exposure unit. apparatus. The image forming apparatus according to claim 16, wherein the exposure length adjusting member is configured to change an angle formed by an optical axis of light emitted from the exposure unit and the photoconductor. An exposure amount setting unit for setting a light emission amount of light emitted from the organic electroluminescence element. The exposure amount setting unit is used for measuring the light emission amount of light emitted from the organic electroluminescence element. 13. The image forming apparatus according to claim 12, wherein a light emission amount of the element is set lower than a light emission amount at the time of image formation to suppress a latent image from being formed on the photoconductor.

Images