JP2008070476A - Exposure unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exposure unit capable of achieving the miniaturization by reducing the number of components, and to provide an image forming apparatus. <P>SOLUTION: In the exposure unit 240 for the image forming apparatus 1, a light emitting element for exposure 244 for forming an electrostatic latent image on an image carrier and a light emitting element for static elimination 244a for eliminating the charge of the image carrier are disposed on a substrate 245. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an exposure unit and an image forming apparatus.

  An image bearing member (photosensitive member) charged in advance at a predetermined potential is exposed according to image information to form an electrostatic latent image, and the electrostatic latent image is developed with toner. A light beam that uses a laser diode as a light source is called a polygon mirror as an exposure device used in an image forming device that applies the so-called electrophotographic process. A system in which an electrostatic latent image is formed by scanning an image carrier through a polygon mirror, and light emitting elements configured using light emitting diodes (LEDs) or organic electroluminescence (organic EL) materials are arranged in a line. There is known a method of forming an electrostatic latent image on an image carrier by individually lighting (ON / OFF) each light emitting unit using a light emitting element array.

  In the method of forming an electrostatic latent image on such an image carrier, after forming an electrostatic latent image on the image carrier, a process of attaching toner particles to the image carrier and a process of fixing a transfer toner pattern are performed. Have. Further, in preparation for the next image formation, photostatic discharge is performed to remove the residual toner on the photoconductor and remove the residual charge on the photoconductor.

In an image forming apparatus having a plurality of image carriers, such as a tandem full-color copying machine, an image forming apparatus that splits light from a single light source and performs light neutralization on the plurality of image carriers is proposed. (For example, refer to Patent Document 1).
Japanese Patent Application Laid-Open No. 2000-221853

  However, in the above-described image forming apparatus, it is necessary to install an LED serving as a single light source for light neutralization separately from a configuration such as an exposure apparatus and a developing apparatus, so the number of parts increases by the amount of the LED. At the same time, it is necessary to provide an installation space for the LED and a light guide that guides the light emitted from the LED to the vicinity of the image carrier, and as a result, the size of the apparatus is increased.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exposure unit and an image forming apparatus capable of reducing the number of parts of the image forming apparatus and reducing the size.

  A first aspect of the present invention is an exposure unit provided in an image forming apparatus having an image carrier and capable of irradiating the image carrier with light, provided on a substrate, and having an electrostatic latent image on the image carrier. An exposure unit is provided that includes an exposure light-emitting element that forms an image, and a charge-removing light-emitting element that is provided on the substrate and charges the image carrier.

  With this configuration, since the light-emitting element for charge removal is provided together with the light-emitting element for exposure on the same substrate, the number of parts and the cost attached to the image forming apparatus can be reduced, and the image forming apparatus can be downsized.

  The present invention secondly provides the exposure unit according to the first aspect, wherein the exposure light-emitting element and the charge-removing light-emitting element are organic electroluminescence elements.

  With this configuration, since the drive circuit and the organic electroluminescence element can be integrally formed on the substrate, the structure and the manufacturing process are simple, and downsizing and cost reduction can be achieved.

  A third aspect of the present invention is the exposure unit according to the first or second aspect, wherein the light-emitting element for charge removal is disposed on an extension line in the arrangement direction of the light-emitting elements for exposure. Is.

  With this configuration, the light-emitting element for exposure and the light-emitting element for charge removal are formed in the same arrangement direction on the substrate, so that the exposure unit can be easily manufactured and the cost can be reduced.

  Fourthly, the exposure unit according to any one of the first to third aspects, wherein the display light-emitting element is provided on the substrate and serves as a light source of a display unit provided in the image forming apparatus. An exposure unit is further provided.

  With this configuration, since the display light emitting element is provided on the same substrate as the exposure light emitting element, the image forming apparatus can be downsized.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising: the exposure unit according to any one of the first to fourth aspects; and a light guide that guides the light emitted from the charge-removing light emitting element to the image carrier. It is provided.

  With this configuration, since the exposure unit in which the light emitting element for exposure and the light emitting element for charge removal are provided on the same substrate is used in the image forming apparatus, the number of parts attached to the image forming apparatus and the cost can be reduced. Miniaturization can be achieved.

  Sixthly, in the image forming apparatus according to the fifth aspect, the light guide body guides light emitted from the charge-removing light emitting element to a plurality of different portions of the image carrier. A forming apparatus is provided.

  With this configuration, the image carrier is neutralized at a plurality of different portions, so that the image quality can be improved.

  Seventhly, in the image forming apparatus according to the fifth or sixth aspect, the image forming apparatus further includes a display unit, and the exposure unit is provided on the substrate, and the display unit provided in the image forming apparatus. And a light emitting element for display, and the light guide is provided with an image forming apparatus that guides light emitted from the light emitting element for display to the display unit.

  With this configuration, since the exposure unit in which the light emitting element for exposure and the light emitting element for charge removal are provided on the same substrate is used in the image forming apparatus, the number of parts attached to the image forming apparatus and the cost can be reduced. Miniaturization can be achieved.

  Eighthly, the present invention provides the image forming apparatus according to any one of the fifth to seventh aspects, wherein the image forming apparatus includes a plurality of the image carriers, and the light-emitting element emits light from the light guide. An image forming apparatus that guides light to each of the plurality of image carriers is provided.

  With this configuration, even in a tandem type image forming apparatus that has a plurality of image carriers and forms a color image, the number of parts and cost attached to the image forming apparatus can be reduced, and the image forming apparatus can be downsized. Can do.

  The ninth aspect of the present invention is the image forming apparatus according to the eighth aspect, further comprising a charger, an exposure unit, a developing unit, and a transfer unit provided around each of the plurality of image carriers. The light guide emits light emitted from the charge-removing light emitting element between the developing unit and the transfer unit and between the transfer unit and the charger for the plurality of image carriers. A leading image forming apparatus is provided.

  With this configuration, the image carrier is neutralized before and after transfer, so that the image quality can be improved.

  The tenth aspect of the present invention is the image forming apparatus according to the eighth or ninth aspect, wherein the light guide is integrally formed, and the light emitted from the light-emitting element for discharging is used as the plurality of images. An image forming apparatus that leads to each of the carriers is provided.

  With this configuration, the light guide that emits the light from the light-emitting element for static elimination is realized with a single component for a plurality of image carriers, so the number of components and cost attached to the image forming apparatus can be reduced, and the image can be reduced. The forming apparatus can be downsized.

  Eleventhly, the present invention provides the exposure unit according to the first or second aspect, wherein the light-emitting element for charge removal is disposed along an arrangement direction of the light-emitting elements for exposure. Is.

  With this configuration, the light-emitting element for exposure and the light-emitting element for charge removal are formed in the same arrangement direction on the substrate, so that the exposure unit can be easily manufactured and the cost can be reduced.

  The twelfth aspect of the present invention is the exposure unit according to the eleventh aspect, wherein an exposure unit in which the light-emitting element for charge removal is composed of a single organic EL element is provided.

  With this configuration, it is possible to easily manufacture a light-emitting element for static elimination, and it is possible to reduce the cost.

  12thly this invention is an exposure unit as described in said 11th, Comprising: The exposure unit which comprised the said light emission element for static elimination with the some organic EL element is provided.

  With this configuration, even if any one of the light-emitting elements for charge removal stops emitting light, the charge removal function can be maintained.

  According to a fourteenth aspect of the present invention, there is provided an exposure unit according to any one of the first to fourth aspects, a developing roller for developing a latent image on the image carrier exposed by the exposure unit, and one of the developing rollers. And an image forming apparatus configured to discharge the image carrier by guiding the light emitted from the discharging light emitting element by the developing roller case. .

  With this configuration, it is possible to reduce the number of parts and reduce the cost.

  According to the present invention, it is possible to provide an exposure unit and an image forming apparatus capable of downsizing the image forming apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Overview of the operation of the image forming apparatus)
First, an outline of an image forming process of an image forming apparatus to which an electrophotographic process is applied will be briefly described with reference to FIG. FIG. 1 is a conceptual diagram of main parts related to an image forming process of an image forming apparatus, and forms a predetermined image on a recording sheet as a transfer material. The transfer material on which an image is formed includes recording media such as plain paper, OHP sheet, coated paper, and recycled paper.

In the example of FIG. 1, the surface potential of the image carrier (photoconductor) is set to −650 V (charge potential V _O ) using a charger, and further transmitted from a host device (not shown) using an exposure unit. Based on the printed data, a part of the image carrier corresponding to the image forming portion is exposed to generate an electrostatic latent image corresponding to the printed portion on the image carrier. The potential of this part (exposure potential V _L ) is set to −50 V, for example. Further, in the developing unit, a developing bias potential for developing the latent image (a developing roller provided in the developing unit when the electrostatic latent image is visualized using a developer (see reference numeral 266 in FIG. 18). ) voltage is applied to) setting V _B for example, -250 V, on the basis of a potential difference between the exposure potential V _L development bias potential V _B, the toner from the developing roller moves, develops the electrostatic latent image, the image bearing member A toner image is generated on the top. By the transfer unit, the toner image on the image carrier is transferred to the recording paper conveyed from the paper cassette, and the transferred image is fixed on the recording paper by the fixing roller and the heating roller to form an image.

  In FIG. 1, as a charger, a so-called scorotron charger is used in which corona discharge is performed by applying a high voltage to a tungsten wire or the like, and the surface potential of the image carrier is controlled by the potential of a grid provided on the image carrier. However, a roller charger may be used as will be described later.

  In FIG. 1, neutralizers 1 to 3 are shown in order to eliminate unnecessary charging on the image carrier. The static eliminator 1 is disposed between the developing unit and the transfer unit, and is mainly used in a tandem type image forming apparatus having a plurality of image carriers as shown in FIG. The static eliminator 1 mainly serves to prevent a so-called reverse transfer phenomenon in which the toner adhered on the transfer material in the upstream image carrier is transferred to the image carrier in reverse. The static eliminator 2 is disposed between the transfer unit and the cleaning unit, and has a main role of improving toner cleaning performance by the cleaning unit. The static eliminator 3 is disposed in front of the charger and serves to initialize the surface potential uniformly, for example, to −50 V by exposing the photoconductor as an image carrier to light, and is generally provided in an image forming apparatus. It is what.

(Description of overall configuration)
FIG. 2 is a cross-sectional view of the image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 includes a housing 10, a main body frame 30, a paper cassette 20, a print engine 100, a paper discharge tray 40, a controller 50, a display unit 60, and a cartridge 70.

  The casing 10 is formed of resin or the like, constitutes an outer frame of the image forming apparatus 1, and stores each member. The main body frame 30 is composed of a metal frame, a resin frame (for example, polycarbonate formed by mixing approximately 20% glass flakes, ABS (acrylonitrile butadiene styrene) as a material), and the like from the inside of the case 10 itself. As well as supporting the print engine main unit 200 of the print engine 100 and other members inside the housing 10 as will be described later. The paper cassette 20 and the paper discharge tray 40 are used in a normal image forming apparatus, and can be attached to and detached from the housing by a user. At the time of printing, the recording paper R as a transfer material is transported along the transport direction D indicated by the arrow in the order of the paper cassette 20, the print engine 100, and the discharge tray 40.

  The controller 50 includes hardware and software for receiving various data (character code, drawing command, etc.) from the outside, creating drawing data, and controlling the print engine 100. The display unit 60 is composed of a liquid crystal display device or the like, and is exposed to a user from a part of the housing 10 so as to display various statuses.

  The cartridge 70 is a container that stores toner (coloring material) to be used for the development described above. The cartridge 70 includes yellow cartridge 70Y for yellow (Y) toner, magenta cartridge 70M for magenta (M) toner, cyan cartridge 70C for cyan (C) toner, and black cartridge 70K for black (K) toner. One included. Each cartridge 70 can be individually replaced according to the shortage of toner, and the user can remove the cartridge 70 short of toner from the housing 10 and attach a new cartridge to the housing 10. The cartridge 70 supplies toner to the stirring unit 262 (stirring unit 261) of the developing unit 260 (FIG. 18) via a tube (not shown) (see arrows in FIGS. 21 and 23).

  Next, the print engine 100 related to the main part of the present invention will be described. The printing engine 100 is a mechanism portion that actually performs printing. Starting from the feeding of the recording paper R, as will be described later, charging and exposure to the image carrier, development, toner transfer to the recording paper, fixing, etc. It is the part in charge of the physical printing process itself.

  The print engine 100 includes a paper feed roller 110, a print engine main unit 200, a fixing device 130, and a discharge roller 140. The paper feed roller 110 is a roller that carries the recording paper R from the paper cassette 20 toward the print engine main unit 200. The print engine main unit 200 performs an image forming process (a so-called Carlson process) other than fixing of an image onto the recording paper R. The print engine main unit 200 corresponds to the image forming unit in this specification. The fixing device 130 includes a pressure roller 131 and a heating roller 132 that is driven by the pressure roller 131 and heats the recording paper R. The image is fixed and formed on the recording paper R by this heating action and the pressure by the pressure roller 131. The discharge roller 140 discharges the recording sheet R on which the image is formed to the discharge tray 40.

  The print engine main unit 200 is a main part of the print engine 100, and is directly attached to the main body frame 30 of the image forming apparatus 1 configured inside the housing 10 as an integral unit. You may attach indirectly through the member. The print engine main unit 200 can be mounted in the housing 10 after being assembled in advance. The print engine main unit 200 corresponds to a part mainly responsible for exposure to the transfer material, development, and image transfer in the image forming process.

  As shown in FIGS. 3 to 7, the print engine main unit 200 includes an image carrier (photoconductor) 201 (201Y, 201M, 201C, 201K), a registration roller 202, a charging roller (charger) 203, a brush cleaner ( Cleaning unit) 204, light guide 205, conveyance guide (transfer material guide member) 206, frame 220, exposure unit 240, development unit 260, and transfer unit 280. In the manufacturing process, the print engine main unit 200 can be manufactured as a single unit by assembling other members as the members for defining the assembly reference position of the frame 220 forming the outer frame.

  As shown in FIG. 3, the print engine main unit 200 is very compact with a sub-scanning direction size = 165 mm, a main scanning direction size = 385 mm, and a height = 70 mm. As will be described in detail later, the print engine main unit 200 includes all the components except for the fixing step for forming a color image by electrophotography. It is possible to significantly improve the rigidity by constructing all elements that require substantially accuracy in image formation integrally (and compactly). Furthermore, by attaching such a highly rigid unit to the main body frame 30 (FIG. 2), it becomes possible to correct distortion on the image forming apparatus main body side (including the housing), and not only the image quality improvement but also the outer shape, for example, There are also secondary effects, such as better aligning with what the designer intended.

  In this embodiment, an image forming unit (print engine main unit 200) is attached to the main body (main body frame 30) of the image forming apparatus, and another unit (exposure unit 240 (FIG. 8) involved in image formation is attached to this image forming unit. Etc.), a development unit 260 (see FIG. 18 etc.), and a transfer unit 280 (see FIG. 30 etc.)) are attached (these units will be described in detail later), and are configured as so-called nested structures. It is a big feature.

  As shown in FIG. 7, the frame 220 has a first sub-frame 221, a second sub-frame 222, each formed of a metal member or the like, and a front of the fixing unit that connects the two sub-frames arranged in parallel and facing each other. The guide 223 is configured. Further, in each of the first sub-frame 221 and the second sub-frame 222, photosensitive member shafts 221a and 222a (only 222a is shown in FIG. 7) for positioning the image carrier 201, and development by a developing unit 260 described later. Developing roller positioning holes 221b and 222b for positioning the roller 266 are formed. Furthermore, transfer material pressing roller positioning holes 221c and 222c for positioning a transfer material pressing roller (transfer material regulating member) 224 (see FIG. 14) described later are formed in each of the first subframe 221 and the second subframe 222. Has been. That is, the first subframe 221 and the second subframe 222 function as positioning members that position the image carrier 201, the developing roller 266, and the transfer material pressing roller 224 at predetermined positions.

  The registration roller 202 is a first driving roller in the print engine main unit 200 and is a member that conveys the recording paper R to the transfer position on the image carrier 201 along the conveyance path P (FIG. 5). The registration roller 202 temporarily stops the recording sheet R that has been transported at that position, prevents skewing of the recording sheet R, and starts driving at a predetermined timing controlled by the controller 50. R is transported along the transport path P. The registration roller 202 is preferably formed of a metal shaft in order to increase the accuracy of the conveyance position and the conveyance speed, and substantially restricts the position of the recording paper R in the conveyance direction of the recording paper R. In this embodiment, a counter roller 202a driven by the registration roller 202 is provided below the registration roller 202, and the recording paper R is sandwiched and conveyed by the registration roller 202 and the counter roller 202a. As described above, the registration roller 202 and the counter roller 202 a function as an entrance side nip unit of the print engine main unit 200 in the transport path P.

As described with reference to FIG. 1, the charging roller 203 applies a predetermined potential (charging potential V _O ) to the image carrier 201 under the control of the controller 50 to charge the image carrier 201. Then, the exposure unit 240 exposes the image carrier 201 based on the print data from the controller 50, and sets the potential of this portion to a predetermined potential (exposure potential V _L ), whereby a print portion (toner adhesion portion). An electrostatic latent image corresponding to is generated on the image carrier 201.

In the developing unit 260, a developing bias potential for developing the latent image (voltage applied to the developing roller 266 (see FIG. 18) when visualizing the electrostatic latent image using a developer) V _B is set. Then, a Coulomb force based on the potential difference between the exposure potential V _L and the development bias potential V _B acts, and only the toner moves out of the developer (mixture of toner and carrier) supplied to the surface of the development roller 266, and electrostatic The latent image is developed to generate a toner image. The transfer unit 280 transfers the toner image on the image carrier 201 onto the recording paper R conveyed from the paper cassette 20.

  The image carrier 201 includes an image carrier 201Y for yellow (Y) toner, an image carrier 201M for magenta (M) toner, an image carrier 201C for cyan (C) toner, and a black (K) toner. The four image carriers 201K are included, and the toner images of the respective colors formed on the image carriers 201 are transferred to the recording paper R. The above-described processes from charging to transfer are performed on each image carrier 201, and yellow (Y), magenta (M), cyan (C), and black (K) color toner images are formed on the recording paper R. Superimposed and transferred.

  The toner images transferred from all the image carriers 201 to the recording paper R are fixed to the recording paper R by the fixing device 130, and as a result, a color image is formed on the recording paper R.

  The brush cleaner (cleaning unit) 204 serves as the cleaning unit shown in FIG. 1, and removes unnecessary toner remaining on the image carrier 201 after the transfer process. The light guide 205 is constituted by an integral resin member that guides light, and plays a role of guiding light used for the charge eliminator 1 (static charge before transfer) and the charge eliminator 3 (static charge before charging) shown in FIG. The light guide 205 will be described in detail later.

An exposure unit 240 is shown in FIGS. As described in the conceptual diagram of FIG. 1, the exposure unit 240 is a member that supports a substrate provided with a light emitting element array composed of a plurality of light emitting elements as will be described later, and the light emitting element array (light emitting section). The image carrier 201 is exposed to light emitted from the image carrier to generate an electrostatic latent image having an exposure potential _VL on the image carrier 201. Details of the exposure unit 240 will be described later.

18 to 29 show the developing unit 260. As described in the conceptual diagram of FIG. 1, the developing unit 260 sets the developing bias potential V _B for developing the latent image on the developing roller 266 provided in the exposure unit 260, and sets the exposure potential _VL and the developing potential. based on the potential difference between the bias potential V _B, to move the toner onto the electrostatic latent image formed by the exposure unit 240, developing the electrostatic latent image to produce a toner image. Details of the developing unit 260 will be described later.

  30 and 31 show the transfer unit 280. FIG. As described in the conceptual diagram of FIG. 1, the transfer unit 280 transfers the toner image on the image carrier 201 to the recording paper R conveyed from the paper cassette 20, and the transferred image is transferred to the fixing roller 131 and the heating roller. An image is formed by being fixed on the recording paper R by the roller 132. A transfer guide (transfer material guide member) 206 (see FIGS. 14 and 31) made of resin or the like is disposed on the lower surface of the transfer unit 280 (the surface on the transfer path P side). Details of the transfer unit 280 will be described later.

  The print engine main unit 200 is completed by placing the transfer unit 280 on the frame 220 in FIG. 7 from the state in which the exposure unit 240 and the development unit 260 are assembled (FIG. 4). 5, FIG. 6). As shown in the sectional view of FIG. 5, the developing unit 260 is fixed in a state of penetrating the exposure unit 240. In this example, as shown in FIG. 3, a main body mounting plate (mounting portion) having a main body mounting screw hole 269a and a main body mounting positioning hole 269b at both ends in the main scanning direction of the developing unit 260 on the lower side of the print engine main unit 200. ) 269 is provided. The completed print engine main unit 200 is mounted on a main body frame 30 (FIG. 2) provided inside the housing 10 after the mounting position is restricted by the main body mounting positioning holes 269 b of the main body mounting plate 269, and then the main body mounting screws. Screws passing through the holes 269 a are screwed to the main body frame 30, whereby the main body mounting plate 269 and thus the print engine main unit 200 are fixed to the main body frame 30.

  Since the print engine main unit 200 according to the present embodiment integrally constitutes main components of the electrophotographic process, the positional deviation of each color at the time of image formation is determined inside the print engine main unit 200. It is possible to ensure accuracy. Therefore, high accuracy is not required for the mounting position of the print engine main unit 200 to the image forming apparatus 1. If each member (image carrier 201 or the like) in the print engine main unit 200 is correctly positioned in the print engine main unit 200 (as described above, the member that is mainly used as a positioning reference is the first sub-unit). When the frame 221 and the second sub-frame 222) and the print engine main unit 200 are incorporated in the housing 10, it is not necessary to perform complicated positioning adjustment, and the manufacturing of the image forming apparatus 1 can be simplified. . In FIG. 4A, the main body mounting plate 269 is not shown.

(Explanation of exposure unit)
Next, details of the exposure unit 240 will be described with reference to FIGS. As shown in FIG. 8, the exposure unit 240 basically includes a plurality of light emitting element arrays (light source arrays) 242 (242Y, 242M, 242C) as a plurality of light emitting units that expose each of the plurality of image carriers 201Y to 201K. , 242K). The support member 241 that supports the plurality of light emitting element arrays is exposed to the image carrier 201 corresponding to each of the light emitting element arrays. As shown in FIG. 6, the frame 220 can be attached to the first subframe 221 and the second subframe 222 using screws 243.

  The light emitting element rows 242Y to 242K are arranged in such a manner that the plurality of light emitting elements (light sources) 244 are arranged in the main scanning direction of the exposure unit 240 (the direction perpendicular to the direction in which the recording paper R is conveyed and the longitudinal direction of the support member). Are arranged in a row (see FIG. 32), and the corresponding image carriers 201Y to 201K are respectively exposed. As a light emitting element, solid light emitting elements, such as a light emitting diode (LED; Light Emitting Diode) and an organic electroluminescent element (organic EL; Organic Electroluminescence), are mentioned. Precisely, the light emitting element arrays 242Y to 242K are formed on a substrate 245 described later.

In the present embodiment, the support member 241 is configured by a single molded member formed by rolling, forging, injection, or the like of a predetermined material. In particular, in the present embodiment, the support member 241 is made of a plate-shaped metal sheet. The degree of temperature rise in the image forming apparatus 1 (which rises by about 20 ° C. with respect to the ambient temperature in which the image forming apparatus 1 is placed) and the effect on the human visual characteristics caused by the amount of misregistration of each color (theoretically 1 / 4 pixels), the resolution of the individual pixels to be formed (the basic resolution is about 600 to 1200 dpi, but is converted to a screen with a predetermined number of lines such as 133 lines / inch), etc. As the material, it is desirable to select a material having a thermal expansion coefficient of 11.8 × 10 ⁻⁶ / ° C. or less.

  With the configuration described above, the number of support members 241 that support the light emitting element arrays can be reduced, and the mounting accuracy between the light emitting element arrays 242Y to 242K can be made uniform and the mounting accuracy can be improved. Furthermore, it is possible to reduce the positional deviation of the light emitting element array accompanying the increase in ambient temperature, and it is possible to easily adjust the mounting position of the light emitting element array when manufacturing the exposure unit 240.

  In the example of FIG. 8, each of the plurality of light emitting element arrays 242Y to 242K is formed on a plurality of substrates 245 (245Y to 245K) independent from each other, in the TFT manufacturing process (in this embodiment, lighting / extinguishing of the light emitting element arrays 242). A circuit for controlling the amount of emitted light is composed of TFTs) and a normal organic EL manufacturing process (in this embodiment, a so-called wet process is used on the substrate 245 on which the above-described TFT circuit and anode are formed. An organic light emitting material is applied, and then a light emitting element is formed by forming a metal cathode using a dry process). A plurality of light emitting elements 244 are arranged in a row in the longitudinal direction of the substrate 245 (longitudinal direction of the support member), that is, the main scanning direction described above (see FIGS. 19 and 32). A light emitting element array 242 including a plurality of light emitting elements 244 is sealed on each substrate 245 with a sealing glass 246. A plurality of such substrates 245 are fixed on the support member 241 via an adhesive. Thus, by forming the light emitting element arrays individually for the substrates, it is possible to prevent the substrate area from being unnecessarily increased and the cost from being increased.

  It is important to accurately measure the distance between the light emitting element arrays 242, that is, the distance between the substrates 245, and fix the substrate 245 at an accurate position of the support member 241. Therefore, as shown in FIG. 9, for example, it is desirable to determine the attachment positions of the other substrates 245M to 245K on the basis of the attachment position of one substrate 245Y to the support member 241. With this configuration, the mounting positions of the plurality of substrates are clarified, and the mounting accuracy can be easily improved.

  As shown in FIG. 9, the substrate mounting position is composed of two elements, a column position P1 determined by the distance between the columns and a reference element position P2 determined by the distance between the positions of the reference light emitting elements at the end. By determining two, the position of the substrate 245 is determined. As this determination process, it is conceivable that a light emitting element is caused to emit light using a jig (not shown), P1 and P2 are determined, and the substrates 245Y to 245K are fixed on the support member 241 with an adhesive.

  The exposure unit 240 further includes imaging lenses 247Y to 247K attached to the support member 241 so as to correspond to the plurality of light emitting element arrays 242Y to 242K. As shown by the optical path OP1 (FIG. 8), the imaging lens plays a role of forming the light emitted from the light emitting element array 242 as an erecting equal-magnification image on the image carrier 201 (that is, as shown in FIG. 8). It is an optical system that performs image transmission). In this embodiment, a bent portion 241a is formed at a position corresponding to each of the light emitting element array 242 and the substrate 245 of the support member 241, and the imaging lens 247 is bonded to the bent portion. In addition, an opening 241c is formed in a corresponding portion of the main plane 241b where the original material for forming the bent portion 241a is present. The light emitted from the light emitting element array 242 passes through the opening 241c and reaches the imaging lens 247. With this configuration, the imaging lens 247 can be easily attached to the support member 241.

  Further, it is preferable that the light transmission directions by the imaging lens 247 are all the same. The support member 241 is molded by sheet metal processing using a predetermined mold, and the bending portion 241a and the main plane 241b are made to have a total angle by bending through a plurality of pressing steps in the processing step. It can be made substantially the same in all the bending parts 241a. By making the angles of all the bent portions 241a substantially the same, the distances between the paired imaging lens 247 and the image carrier 201 are the same in all the optical systems. As a result, the MTF (Modulation) of the optical system is the same. Transfer Function) can be made uniform. Examples of the imaging lens 247 include a SELFOC (registered trademark of Nippon Sheet Glass Co., Ltd.) lens, but are not particularly limited.

  The MTF is greatly affected by the separation distance between the surface of the imaging lens 247 and the image imaging position of the image carrier 201 that is paired with the surface of the imaging lens 247 (that is, an error from the focal length of the imaging lens 247). From this viewpoint, in the manufacturing process of the print engine main unit 200, as shown in FIG. 8B, on the optical axis center of each imaging lens 247 (that is, the center position of the imaging lens 247 in the sub-scanning direction). The distance Ls_o between the surface of the imaging lens 247 and each image carrier 201 may be adjusted equally.

  Based on this aspect of the present embodiment, a process of fixing the imaging lens 247 to each bent portion 241a of the support member 241 will be described. First, the support member 241 to which the plurality of substrates 245 are fixed by the steps already described is set on a jig (not shown). In this jig, an optical sensor (for example, an area sensor using a CCD) including a two-dimensional array is provided at a position where the image carrier 201 is disposed in a later process. In this state, when the light emitting element formed on the substrate 245 emits light, the light emitted from the light emitting element forms an image on the optical sensor by the imaging lens 247. The in-plane light quantity distribution is measured based on the light spot imaged on the optical sensor, and as a result, a latent image is formed (more precisely, the three-dimensional potential distribution of the latent image and the development potential Based on the relationship, the effective area of the light spot can be observed. The mounting position of the imaging lens 247 can be determined by adjusting the distance between each imaging lens 247 and the optical sensor so that the area becomes a predetermined value. The jig is provided with at least two optical sensors. For example, by measuring the light amount distribution of the light emitting elements located at or near both ends in the main scanning direction, the imaging lens 247 in the main scanning direction is measured. By determining the positions of both ends, the overall position of the imaging lens 247 is determined.

  The imaging lens 247 has a configuration in which a plurality of rod lenses having a diameter of about 0.6 mm are arranged in one or a plurality of rows in the main scanning direction shown in FIG. 8, and the light emitted from one light emitting element is a plurality of light beams. An image is formed on the optical sensor via the rod lens. Therefore, as the distance between the imaging lens 247 and the optical sensor deviates from the focal length of the imaging lens 247, the light spot imaged on the optical sensor is decomposed into a plurality. From this point of view, the imaging lens 247 is gradually brought closer to the optical sensor from a distant position, and the fixed position of the imaging lens 247 is determined when a plurality of light spots converge to one. May be. Further, the imaging lens 247 may be fixed at a position where the area of the light spot is minimized.

  The method for attaching the substrate 245 in FIG. 9 is determined based on the light emission of the light emitting element before the imaging lens 247 is attached. However, in an actual use state, the image carrier 201 is irradiated with light after passing through the imaging lens 247. Therefore, as shown in FIG. 10, the attachment position of the substrate to the support member 241 may be determined based on the imaging position of the light after passing through the imaging lens 247. As shown in the figure, with reference to the light emitting element array 242Y, (1) the distance between the light emitting element array 242Y and the light emitting element array 242M, (2) the distance between the light emitting element array 242Y and the light emitting element array 242C, and (3) the light emitting element array 242Y All the substrates can be positioned by sequentially measuring and positioning the distance of the light emitting element array 242K. With this configuration, the imaging position of the light after passing through the imaging lens 247 is used for attachment positioning, and the board can be attached more appropriately in the mounting state. Furthermore, by doing so, it is possible to perform the process of determining the mounting positions of the substrate 245 and the imaging lens 247 using a single jig, and the tact time during manufacturing can be shortened. It becomes.

  A plurality of substrates 245Y to 245K are fixed to the main plane 241b (more precisely, the back surface of 241b shown in FIG. 8) which is the same plane and the common plane on the support member 241 with an adhesive. With this configuration, it is possible to easily attach a plurality of substrates to the support member 241.

  Another embodiment of the exposure unit 240 is shown in FIG. In the present embodiment, unlike those shown in FIGS. 8 to 10, all the light emitting element arrays 242 </ b> Y to 242 </ b> K are formed on a single substrate 245. In other words, at least two light emitting element rows are formed on a single substrate 245, and the substrate is fixed on the support member 241 with an adhesive. With this configuration, it is possible to ensure the positional accuracy of the light emitting element array within the single substrate 245, and it is possible to simplify the adjustment during assembly.

  In both the example of FIG. 8 and the example of FIG. 11, the light extraction surface of the substrate 245 (245 </ b> Y to 245 </ b> K) is fixed in contact with the support member 241. In particular, when an organic EL element is used as a light-emitting element, a glass substrate is often used as the substrate 245 in order to make the surface opposite to the surface on which the organic EL element is formed as a light extraction surface (bottom emission structure). The light extraction surface is a surface of the substrate 245 that is in contact with the main plane 241b (more precisely, the back surface thereof), and is a surface perpendicular to the optical path OP1 in the illustrated example. Since the surface of the glass substrate is extremely smooth, this structure increases the degree of fixation of the substrate 245 to the support member 241, further improves the mounting accuracy, and also reduces misalignment due to an increase in ambient temperature. It becomes possible to make it.

  Further, when the substrate 245 is a glass substrate, light is transmitted. Therefore, by using a UV curable adhesive and irradiating the UV light from the glass substrate side, the bonding can be performed in a short time. Further, if priority is given to the hardness when cured, the substrate 245 may be attached to the support member 241 using a thermosetting adhesive, and at this time, a UV curable adhesive is used for temporary fixing. May be.

  In particular, in the example of FIG. 8, at least one side of the light extraction surface of the substrate 245 in the longitudinal direction (longitudinal direction of the support member 241) is fixed in contact with the support member 241 over substantially the entire length. That is, the substrate 245 is not in contact with the support member 241 in the portion corresponding to the opening 241c. However, even in this configuration, since the substrate 245 is bonded to the support member 241 over the entire length, as a result, the degree of fixation to the support member 241 is increased, the mounting accuracy is further improved, and the displacement due to a rise in ambient temperature, etc. Can be further reduced.

  In other words, in the exposure unit 240 of the present invention, a substrate 245 provided with a light emitting element array 242 is fixed substantially integrally to a support member 241 formed of a single molded member. Here, “substantially integrated” means that the substrate 245 does not cause physical deformation such as bending, warping, distortion, and twisting, which is actually harmful, separately from the support member 241. This means that the substrate 245 and the support member 241 are integrally formed, and includes both configurations of FIGS. 8 and 11. From this point of view, the imaging lens 247 described above is configured substantially integrally with the support member 241 as well.

  With the above-described configuration, the exposure unit 240 including one or more substrates 245 on which light emitting elements are formed and the imaging lens 247 as an optical system has extremely high rigidity against external stress. As a result, the exposure unit 240 can be incorporated into the print engine main unit 200 as a single member.

  8 to 11, the substrate 245 is disposed on the opposite side of the image carrier 201 as viewed from the support member 241 (for example, the back surface of the main plane 241b shown in FIG. 8). With this configuration, it is possible to secure a space for arranging other components on the same side as the image carrier 201 when viewed from the support member 241. On the other hand, in the example of FIG. 12, the substrate 245 is disposed on the same side as the image carrier 201 as viewed from the support member 241 (main plane 241b shown in FIGS. 8A and 8B). With this configuration, it is possible to secure a space for arranging other components on the opposite side of the image carrier 201 when viewed from the support member 241.

  In this case, the surface of the substrate 245 on which the light emitting element is formed (that is, the surface on which the sealing glass 246 is disposed) is bonded to the support member 241. Since the surface on which the sealing glass 246 is disposed usually includes not only a light emitting element but also a TFT circuit and the like, the bonding position Pcnt should be a position not including these components. At this time, the positional relationship may be such that the protruding portion of the substrate 245 such as the sealing glass 246 corresponds to the opening 241c.

  The configuration shown in FIG. 12 is advantageous when a so-called top emission structure is adopted in which the surface on which the organic EL element is formed is the light extraction surface. In the case of the top emission structure, no structure such as a drive circuit is provided on the back surface side of the light extraction surface (that is, the surface on which the sealing glass 246 is disposed) in the substrate 245. Therefore, there is no unevenness on this surface. It has a flat glass surface. Therefore, the flat surface may be bonded to the support member 241. In this configuration, it is not necessary to provide the opening 241 in the support member 241, but by forming the bent portion 241 a in the support member 241, the attachment position of the imaging lens 247 is secured, and the rigidity of the support member 241 as a whole is further increased. In view of this, it is desirable to actively provide the opening 241c.

  Then, as described above, the exposure unit 240 of the present invention uses the support member 241 and the main body of the image forming apparatus 1 so that each of the light emitting element arrays 242Y to 242K exposes the corresponding image carrier 201Y to 201K. In particular, in the present embodiment, as shown in FIGS. 3 to 6, the first sub-frame 221 and the second sub-frame 222 of the frame 220 are configured to be attachable using screws 243 (however, the sub-frame is not shown). The screw position on the frame 221 side is not shown). There is a slight play in the sub-scanning direction (see FIG. 3) at the tightening position of the screw 243, and when performing final adjustment using a jig or the like (not shown), The position of the support member 241 and the entire exposure unit 240 can be adjusted relative to the image carrier 201.

  In the conventional image forming apparatus disclosed in Patent Document 1 or the like, a plurality of sets of light emitting units represented by light emitting element arrays (or exposure apparatuses themselves) may be provided, and each light emitting unit corresponds to a unique image carrier. In such a case, it is necessary to perform positioning individually for each light emitting unit, and workability may be deteriorated. In addition, there is a high possibility that positional deviation will occur individually for each light emitting unit between the time of manufacture and use, and the workability may be further deteriorated.

  On the other hand, in the present invention, a plurality of sets of light emitting sections each composed of a plurality of light emitting element arrays 242Y to 242K are supported by an integral support member 241, and the support member 241 is a print engine main unit having an image carrier 201. The position adjustment of a plurality of sets of light emitting units and image carriers can be performed by a single mounting operation for mounting on 200. Therefore, workability can be greatly improved.

  Further, even after the support member 241 is attached to the print engine main unit 200 having the image carrier 201 and eventually to the main body of the image forming apparatus 1, the screw 243 is adjusted so that the light emitting portion relative to the image carrier is adjusted. The attachment position can be easily adjusted.

  The process of attaching the substrate 245 on which the light emitting element array 242 is formed on the support member 241 and the imaging lens 247 (exposure unit manufacturing process) is the manufacturing process of the print engine main unit 200 or the manufacturing of the image forming apparatus 1. It is possible to make it completely independent of the process.

  As can be easily understood from the above description, an exposure unit 240 having a multi-line configuration capable of simultaneously exposing a plurality of image carriers 201 by this exposure unit manufacturing process is provided.

(Description of transport mechanism)
Next, a transport mechanism for the recording paper R from the print engine main unit 200 to the fixing device 130 will be described with reference to FIGS.

  As shown in FIG. 5, in the print engine main unit 200, there is a gap between the image carrier 201 and the transfer unit 280 provided above the image carrier 201, particularly the conveyance guide 206 provided on the lower surface of the transfer unit 280. A conveyance path P for conveying the recording paper R is defined (delimited). Since the recording paper R is nipped and conveyed by the registration roller 202 and the counter roller 202a, the nip formed by the registration roller 202 and the counter roller 202a also forms part of the conveyance path.

  FIG. 13 conceptually shows problems that may occur when the recording paper R is conveyed in a conventional tandem type image forming apparatus. In a tandem type image forming apparatus, in particular, a configuration in which a toner image is directly transferred to a recording paper R conveyed from the image carrier 201, a plurality of image carriers 201Y to 201K are generally formed of the recording paper R. Arranged in the transport direction. However, recording is performed between the image carriers 201Y to 201K due to various factors such as friction caused by contact between the recording paper R and the image carriers 201Y to 201K being conveyed, and differences in the outer peripheral speed of the image carriers. The deflection of the paper R may occur.

  As shown in FIG. 13, when deflection occurs at a plurality of locations, the amount of deflection, that is, the length in the conveyance direction between the image carrier 201 of the bent recording paper R (the deflection amount from the conveyance guide 206 to the vertical direction). The direction deflection may be defined in many cases. In such a case, the distance between the image carrier and the recording paper R coming into contact with the transfer position to which the toner image is transferred from the image carriers 201Y to 201K (the conveyance direction of the recording paper R between the image carrier 201). ) Is relatively shifted on the recording sheet R, and a position shift (also referred to as transfer position shift, color shift, etc.) of a single color image for each color on the recording sheet R occurs. Such a phenomenon causes deterioration of a color image finally formed on the recording paper R.

  Therefore, in the embodiment of the present invention, as shown in FIG. 14, a transfer material pressing roller (transfer material regulating member) 224 is provided at an intermediate position between adjacent image carriers 201 in the conveyance path P. As described above, the transfer material pressing roller 224 is rotatably fixed to the transfer material pressing roller positioning holes 221c and 222c of the first subframe 221 and the second subframe 222 shown in FIG. (Dotted line in FIG. 7).

  Actually, the transfer material pressing roller 224 has a function of substantially defining the transport path P of the recording paper R by restricting the transport position of the recording paper R.

  The transfer material pressing roller 224 attaches the recording paper R conveyed along the conveyance path P to the side where the image carriers 201Y to 201K are disposed, in FIG. 14, the lower side (direction away from the conveyance guide 206). It is configured so that With this configuration, it is possible to prevent the recording paper R from being bent between the image carriers 201Y to 201K, and to prevent a transfer position shift of the toner image between the image carriers 201Y to 201K.

  The above configuration is also defined as follows. That is, the transfer surface is defined by two transfer positions at which the toner image formed on the adjacent image carrier 201 is transferred onto the recording paper R as a transfer material and the single color image is transferred onto the recording paper R. At this time, at least a part of the transfer material pressing roller 224 protrudes to a restriction position closer to the rotation center axis of the image carriers 201Y to 201K than the transfer surface. In the example of FIG. 14, the transfer surface PL is defined by the transfer positions PT1 and PT2 of the image carriers 201Y and 201M, respectively, and the lower end of the transfer material pressing roller 224 is the restriction position PR close to the rotation center axis of the image carriers 201Y and 201M. Protrudes up to. Further, the transfer positions PT1 and PT2 are defined at the closest part of the corresponding image carrier (in this case, the image carriers 201Y and 201M) with respect to the transfer wire 282 in the transfer unit 280. Details of the transfer unit 280 will be described later.

  The transfer position described above is actually defined by a straight line that is aligned in the depth direction of the screen and substantially in the same direction as the light emitting element array direction of the exposure unit 240 (main scanning direction, see FIG. 3).

  Here, how much the recording paper R is urged toward the side on which the image carriers 201Y to 201K are arranged, the so-called urging amount of the recording paper R (that is, the amount of protrusion of the transfer material pressing roller 224 to the conveyance path P). ) Is a problem. As one method of determining the urging amount, the amount of deflection that occurs when the recording paper R bends spontaneously (ie, by its own weight defined by the basis weight) without the action of the transfer press roller 224 during conveyance. It is conceivable to secure an energizing amount larger than that. The amount of deflection is determined by the weight of the recording paper R, the attractive force acting on the recording paper R by the image carriers 201Y to 201K, and the rigidity (roughness) of the recording paper R. The energizing amount may be set in consideration of the type of recording paper R that can be printed in step (b).

  It is known that the deflection amount of the recording paper R changes depending on the moisture contained in the recording paper R. Because of such circumstances, the biasing amount is determined based on the maximum value of the deflection amount in consideration of the environment where the image forming apparatus is placed.

  However, on the other hand, when the biasing amount of the transfer material pressing roller 224 is set based on the maximum value of the deflection as described above, for example, when the recording paper R having a large basis weight and a strong stiffness is conveyed, There is a possibility that the transfer material pressing roller 224 may become an obstruction factor when the paper is passed. As a countermeasure, in this embodiment, the recording paper R contact portion of the transfer material pressing roller 224 is configured by a curved surface as will be described later. However, in order to remove the adverse effect, for example, the transfer material pressing roller 224 is a plate. It is good also as a structure supported through elastic bodies, such as a spring.

  Further, due to the configuration of the print engine main unit 200, the transfer material pressing roller 224 is disposed on the same plane in the state where the transfer material pressing roller 224 is supported by the first subframe 221 and the second subframe 222 (see FIG. 7) and in the vicinity thereof. Since there are no other components (FIG. 14), for example, three transfer material pressing rollers 224 are configured as an integrated subunit, and this is configured as a predetermined actuator (for example, a stacked piezo element or a predetermined drive source). It may be configured to be displaceable in both directions of Dr_1 or Dr_2 by an eccentric cam or the like connected to. In this case, the amount of deflection of the transported recording paper R is estimated by a humidity sensor or the like provided in the image forming apparatus, such as input power to a drive source (not shown) when transporting the recording paper R, and then transferred. The material pressing roller 224 is displaced to either Dr_1 or Dr_2. For example, if the humidity of the recording paper R is large (when the humidity is high), and if the rigidity of the recording paper R is large (the power input to the drive source that transports the recording paper R is generally large), the above-described operation is performed so as to be displaced in the direction Dr_1. What is necessary is just to control an actuator. In determining the control amount at this time, for example, a method in which input values are divided into a plurality of ranges and a table is referred to may be used, or fuzzy inference may be used.

  By setting the urging amount as described above, as shown in FIG. 14, the recording sheet R is always on the lower side of FIG. 14, that is, on the side where the image carriers 201Y to 201K are arranged. It is conveyed while being urged by the positive action of 224. Therefore, as shown in FIG. 13, due to the spontaneous (natural) deflection of the recording paper R, the length in the transport direction between the image carriers 201 is different at each location (in the case of four image carriers 201). The length in the conveyance direction between adjacent image carriers 201 of the recording paper is based on the biasing amount given by the positive action of the transfer material pressing roller 224. Is almost the same. Therefore, it is possible to prevent a transfer position shift of the toner image between the image carriers 201.

  Further, the same effect can be obtained even if the size of the transfer material pressing roller 224 is designed so that the distance from the transfer surface PL to the regulation position PR becomes larger than the deflection amount of the recording paper R described above.

  It is preferable that at least the position where the leading edge of the conveyed recording paper R comes into contact, that is, the outer surface of the transfer material pressing roller 224 in the vicinity of the regulation position PR from the main surface of the conveyance guide 206 is formed of a curved surface. With this configuration, it is possible to smoothly convey the recording paper while preventing bending and the like. For example, the transfer material pressing roller 224 may be configured by a shaft member having a circular cross section such as a metal shaft. However, the shape and material are not particularly limited.

  In the mechanism in which the recording paper R is separated from the image carrier (photosensitive member) 201, generally, the stiffness of the recording paper R is dominant, so when the recording paper R is separated from the image carrier 201, The leading edge of the recording paper R always faces the image carrier 201 (the direction away from the conveyance guide 206). Therefore, when a metal shaft or the like is used as the transfer material pressing roller 224, the angle (the “normal line” in FIG. 14) at which the main surface of the conveyance guide 206 and the transfer material pressing roller 224 formed of the metal shaft intersect is vertical. If so, there is no particular problem.

  As described above, the transfer material pressing roller 224 is fixed to the first sub-frame 221 and the second sub-frame 222 as positioning members. With such a configuration, the image carrier 201 and the transfer material are transferred. It becomes possible to improve the relative positional accuracy between the pressing rollers 224.

  In addition, of the entire conveyance path P of the recording paper R, the conveyance guide 206 defines a substantially total length of a portion corresponding to the image carriers 201Y to 202K. The transfer material pressing roller 224 urges the recording paper R on the side facing the image carriers 201Y to 202K across the conveyance path P and closer to the image carrier 201 than the conveyance guide 206. Yes.

  What is necessary for the transfer material pressing roller 224 described in the present embodiment is a function of “equalizing the transport distance of the recording paper R that is conveyed between the image carriers 201 and between the image carriers 201”. As can be easily understood from this, the transfer material pressing roller 224 is not necessarily a roller, and for example, a member having a tapered shape at the initial contact position with the recording paper R may be used. The taper may be provided in a plane or a predetermined curved surface.

  As shown in FIGS. 7 and 14, the first subframe 221 and the second subframe 222 are connected to the downstream side of the transport path P of the transport guide 206 and upstream of the fixing device 130. A fixing unit front guide 223 is provided. FIG. 15A is an overall perspective view of the fixing unit front guide 223, and positioning bosses 223a and fixing screw holes 223c are provided at both ends. As shown in FIG. 15 (b), the positioning boss 223a is positioned relative to the first subframe 221 and the second subframe 222, and the fixing screw 223b is fixed to the fixing screw hole across the subframes. The fixing unit front guide 223 is connected and fixed to the first sub-frame 221 and the second sub-frame 222, respectively. The fixing device front guide 223 guides the recording paper R to the fixing device 130 with the recording paper R facing downward as shown in FIG.

  Further, a driving roller for conveying the rotating recording paper R such as a registration roller 202, a pressure roller 131 (a pair of rollers 131a and 131b in FIG. 14) that drives a heating roller 132 in the fixing device 130, and an image carrier 201Y. Also by adjusting the outer peripheral speed (peripheral speed) of the rotating member such as ~ 202K, it is possible to suppress the occurrence of deflection and suppress the image positional deviation. Generally, by setting the outer peripheral speed of the rotating member on the downstream side of the conveyance path P to be equal to or higher than the outer peripheral speed of the upstream rotating member or larger than the outer peripheral speed of the upstream rotating member, such an effect can be obtained. It is thought that it can be generated. This is because, if such a configuration is adopted, it is considered that a greater tension is applied to the portion of the recording paper that is on the downstream side, and bending is less likely to occur. For example, assuming that the outer peripheral speed of the registration roller 202 is Vr, the outer peripheral speeds of the image carriers 201Y, 201M, 201C, and 201K are Vy, Vm, Vc, Vk, and the outer peripheral speed of the pressure roller 131 is Vp, (1) Vr ≦ It is preferable to control each member so that a relationship of Vy = Vm = Vc = Vk ≦ Vp or (2) a relationship of Vr ≦ Vy ≦ Vm ≦ Vc ≦ Vk ≦ Vp is established. The relationship shown in (2) can also be obtained by gradually increasing the outer diameter of the image carrier 201.

  From one viewpoint of the relationship (1) and (2) above, the outer peripheral speed of the first image carrier (for example, 201Y) among the plurality of image carriers 201 is set along the conveyance path P of the recording paper R. It is derived that the second image carrier (201M to 201K) provided on the downstream side of the first image carrier is set to be equal to or smaller than the outer peripheral speed of the second image carrier. .

  From another viewpoint of the relationship (1) and (2), the recording paper R is provided on the upstream side of all the image carriers 201Y to 201K along the conveyance path P of the recording paper R, and the recording paper R is conveyed. When the roller that substantially restricts the position of the recording paper R is the first drive roller (corresponding to the registration roller in the example of FIG. 14), the outer peripheral speed of the first drive roller is such that the adjacent image carrier 201Y It is derived that the setting is equal to the outer peripheral speed or smaller than the outer peripheral speed of the image carrier 201Y.

  From still another point of view of the relationship (1) and (2) above, all the image carriers 201Y to 201K are provided on the downstream side of the recording paper R along the conveyance path P, and formed on the recording paper R. When the heating roller 132 that fixes at least one monochrome image on the recording paper R is a second driving roller that is driven with the recording paper R in between (the pressure rollers 131a and 131b in the example of FIG. 14), the second driving It is derived that the peripheral speed of the roller is set equal to the peripheral speed of the adjacent image carrier 201K or larger than the peripheral speed of the image carrier 201K.

  As described above, any one of the configuration of adopting a transfer material regulating member such as the transfer material pressing roller 224 and setting the outer peripheral speed of the drive roller (registration roller 202, pressure rollers 131a and 131b) and the image carrier 201 is used. In addition, it is possible to suppress the variation in the deflection of the recording paper R, prevent the image transfer position shift, and ensure the quality of the color image. Moreover, these structures can also be combined and it becomes possible to ensure quality more reliably by the structure of such a combination.

  Incidentally, there are other factors that cause the transfer position deviation besides the above-described deflection of the recording paper R. For example, the shape of each member, dimensional error, the shape between members, and the dimensional error may affect the conveyance speed and cause a transfer position shift.

  For example, in a member that rotates by itself such as the drive roller described above and conveys a transfer material such as the recording paper R, it is desirable that the cross section be a perfect circular shape in order to ensure a constant conveyance speed. . However, it is difficult to manufacture a roller having a perfect circular shape in actual manufacturing. This also applies to the first and second drive rollers (registration roller 202, pressure roller 131).

  When two drive rollers having such a cross section that is not completely circular are mounted, periodic (for example, sine wave) speed fluctuations occur independently on the upstream side and downstream side of the transfer material being conveyed. Become. Such a phenomenon may cause a change in the conveyance speed at both ends of the transfer material, which may cause a transfer position shift.

  Therefore, in the embodiment of the present invention, as shown in FIG. 14, a portion that transfers the image formed on the image carrier 201 onto the recording paper R conveyed along the conveyance path P is regarded as an image forming unit. (A general term for the image carriers 201Y to 201K, the exposure unit 240, the transfer unit 280, etc.), a first drive roller (in the example of FIG. 14, a registration roller) that carries the recording paper R into the image forming unit on the upstream side of the transport path P 202) and the second drive roller (pressure rollers 131a and 131b) for carrying out the recording paper R from the image forming unit on the downstream side of the conveyance path P, and the outer diameter and the second drive of the first drive roller. The outer diameter of the roller is substantially equal.

  Both rollers are members (nip means) that substantially control the conveyance of the recording paper R. By making these outer diameters substantially equal, the phase shift of the outer peripheral speed change of both rollers is maintained constant. It will be. Therefore, since the difference in the outer peripheral speed between the two rollers at a predetermined position, that is, at the transfer position is constant, stable image transfer is possible.

  It should be noted that not only the outer diameter of the first driving roller and the outer diameter of the second driving roller but also the phase of the change in the outer peripheral speed of the two driving rollers can be configured to substantially coincide. Specifically, after the drive roller is assembled to the print engine main unit 200, the drive roller is connected to an external drive source (such as a motor (not shown)) by a jig and rotated. Naturally, the transmission system for transmitting the motor and the driving force of the motor to the driving roller has the same specifications as the image forming apparatus as a finished product. Then, the rotational speed fluctuation of the driving roller at this time is measured, and for example, the positional relationship (meshing position) between the driving roller and the gear just before is adjusted so that the speed fluctuation phases of the plurality of driving rollers coincide. That's fine.

  In the present embodiment, a counter roller 202a is provided in addition to the registration roller 202 as the first driving roller, and these two rollers constitute a registration roller pair. With this configuration, the recording paper R can be reliably conveyed into the image forming unit.

  Further, in the present embodiment, the fixing device 130 for fixing the image transferred onto the recording paper by the image forming unit is provided, and the fixing device 130 is configured and driven by the pressure roller 131 as the second driving roller. It is configured. Furthermore, in this embodiment, by providing at least two pressure rollers 131a and 131b, a larger nip amount necessary for fixing an image is secured. As described above, the plurality of pressure rollers 131a and 131b are provided, and the recording paper R is sandwiched and conveyed by both of them, so that sufficient heat is applied to the toner images formed on the recording paper R and the recording paper R from the heating roller 132. Supplied and properly fixed.

  In the conventional image forming apparatus, an intermediate medium such as a transfer belt is provided between the image carrier and a transfer material such as recording paper, and the image is once transferred from the image carrier to the transfer belt, and then from the transfer belt. Many of them were transferred to a transfer material. The transfer belt in such a conventional configuration is distinguished from the transfer material in the present invention. In the transfer material such as the recording paper R of the present invention, an image (toner image) to be finally fixed is an image. Transferred directly from the carrier.

  In the configuration in which the outer diameters of the two drive rollers described above are substantially equal and the rotation period is the same, as illustrated in the present application, the image carriers 201Y to 201K are arranged along the conveyance path in the image forming unit. The image carrier 201 is not limited to a tandem type, and the image carrier 201 has a so-called monochrome image forming apparatus or an intermediate transfer medium, which is rotated a plurality of times, and a single color image is synthesized on the intermediate transfer medium to obtain a color. The present invention can also be applied to an image forming apparatus that forms an image (a so-called 4-pass color image forming apparatus). When applied to the image forming apparatus of FIG. 14 which is a tandem type and has a plurality of image carriers 201, the position of the recording paper R along the conveyance path P is upstream of all the image carriers 201 </ b> Y to 202 </ b> K. A registration roller 202 that substantially restricts the image quality is provided, and further, a recording sheet is formed by transferring a monochrome image formed on each image carrier downstream of all the image carriers 201Y to 202K along the transport path P. A heating roller 132 that heats and fixes the image formed on the recording sheet R and a pressure roller 131 that sandwiches and conveys the recording sheet R between the heating roller 132 are provided. The outer diameters of the registration roller 202 and the pressure roller 131 are set to be approximately equal.

  There are other problem factors that may occur in a tandem type image forming apparatus. FIG. 16 is a conceptual diagram for explaining such factors. As indicated by the dotted line and the solid line, when the cross section of the registration roller 202 is not a perfect circle, the outer peripheral speed fluctuates. When the outer peripheral length of the registration rollers 202 is different from the pitch between the image carriers, as indicated by the dotted line, the outer peripheral speed of each of the image carriers 201Y to 201K, and hence the conveyance speed of the recording paper R, is different. It will be. Accordingly, a transfer position shift occurs, and the image quality deteriorates.

  Therefore, in this embodiment, the outer peripheral length of the first driving roller (registration roller 202) and the outer peripheral length of the second driving roller (pressure rollers 131a and 131b) are recorded in consideration of the deflection amount as described above. It is set to be approximately equal to the length in the conveyance direction corresponding to the length during conveyance of the paper R. That is, in FIG. 14, the length of the recording paper R between the transfer positions PT1 and PT2 of the image carriers 201Y and 201M is substantially equal to the outer peripheral length of the registration roller 202 and the pressure rollers 131a and 131b.

  Note that the outer peripheral length of the first driving roller (registration roller 202) and the outer peripheral length of the second driving roller (pressure rollers 131a and 131b) are determined during the conveyance of the recording paper R in consideration of the deflection amount as described above. Even if it is configured to be an integral multiple of the length, the same effect can be obtained. Therefore, at this time, the length of the recording sheet R between the transfer positions PT1 and PT2 is substantially equal to an integral multiple of the outer peripheral lengths of the registration roller 202 and the pressure rollers 131a and 131b.

  As a result of such a configuration, as shown by the solid line in FIG. 16, even when the cross section of the registration roller 202 is not completely circular and the outer peripheral speed fluctuates, the outer peripheral length of the registration roller 202 is increased. And the length in the conveyance direction of the recording paper R between the image carriers are set substantially equal, the outer peripheral speeds of the image carriers 201Y to 201K, and consequently the conveyance speed of the recording paper R, can be made substantially the same. Become. Thereby, the shift of the transfer position can be prevented, and the deterioration of the image quality can be prevented.

  In the actual printing process, the length of the recording sheet R in the transport direction between the image carriers 201 (the length of the transfer material) in the above-described idea is equal to the arrangement pitch of the plurality of image carriers. Can be considered. This is because, in an actual printing process, the amount of downward deflection is slightly smaller than the length of the recording paper R in the transport direction. Therefore, in the actual design, the arrangement pitch of the image carrier 201 can be set so as to be substantially equal to the outer peripheral length of the registration roller 202 and the pressure rollers 131a and 131b. That is, in the example of FIG. 14, registration roller outer circumference length≈pressure roller outer circumference length≈pitch A≈pitch B≈pitch C. Here, the pitch A is the arrangement pitch of the image carriers 201Y and 201M, the pitch B is the arrangement pitch of the image carriers 201M and 201C, and the pitch C is the arrangement pitch of the image carriers 201C and 201K. It is determined by the distance between the rotation center axes of the two image carriers.

  As already described, since the same effect can be obtained even if the integral multiple of the outer peripheral length of the driving roller is substantially equal to the arrangement pitch of the image carrier, the registration roller outer peripheral length × N≈pressure roller outer peripheral length × M≈pitch A ≈Pitch B≈Pitch C (where N and M are integers of 1 or more) may be satisfied.

  Furthermore, in this embodiment, as shown in FIG. 17, the rotation shaft of the registration roller 202 as the first drive roller is configured to have a so-called outer periphery receiving structure. That is, both end portions of the registration roller 202 pass through the center portions of the bearings 221d and 222d assembled to the first subframe 221 and the second subframe 222 of the frame 220 (see FIG. 7), and the bearings The outer periphery is received. The protrusions 221e and 222e of the bearings 221d and 222d are fitted into the corresponding concave portions of the subframe to prevent the bearing itself from rotating. With this configuration, shake due to the rotation of the registration roller 202 is restricted on the bearing side, and shake due to an error in the length from the central axis to the outer peripheral surface of the registration roller 202 (in short, a radius error) is prevented. It is possible to prevent the transfer position from shifting. In addition, it is preferable to adopt the same outer periphery receiving structure for the rotation shafts of the pressure rollers 131a and 131b.

  Focusing further on the downstream side of the above configuration, a discharge roller 140 that discharges the recording paper R to the outside is provided at the end of the conveyance path P (a pair of discharge rollers in the example of FIG. 2). The discharge roller 140 feeds the recording sheet R that has been fixed to the outside of the image forming apparatus 1. It is desirable that the grip force is at least smaller than the grip force of the pressure roller 131 and the heating roller 132 so that the driving of the discharge roller 140 does not affect the upstream image forming process.

(Explanation of development unit)
Subsequently, the developing unit 260 of the present embodiment will be described with reference to FIGS. The developing unit 260 is supplied with toner from each of the cartridges 70Y to 70K in FIG. 2 via a tube (not shown), and converts the latent images (electrostatic latent images) on the image carriers 201Y to 201K to developer toner. To develop a toner image (monochromatic image).

  As shown in FIG. 18, the developing unit 260 basically includes a developing roller 266 that constitutes a developing unit that supplies developer to the image carrier 201, and a plurality of developers that stir the developer supplied to the developing roller 266. And a stirring unit 261 constituting the stirring unit 262. As will be described later, in this embodiment, the relative positions of the developing roller 266 and the stirring unit 261 (stirring unit 262) can be changed. In the present embodiment, so-called two-component development is adopted in which the developer is composed of toner and carrier, and only the toner contributes to development.

  FIG. 19 shows a developing roller 266 (266Y, 266M, 266C, 266K) constituting the upper half of the developing unit 260 and a developing roller case 267 (267Y, 267M, 267C, 267K) for housing at least a part of the developing roller. Shown (see FIG. 27). Although not explicitly shown in FIG. 19, the developing roller case 267 includes a part of a light guide 205 described later. The light guide body 205 and the developing roller case 267 are made of a light-transmitting resin, and the first light exit port 267a emits static elimination light before transferring the toner image onto the recording paper R (see FIG. 1). The charge removal light after the cleaning by the brush cleaning 204 of the image carrier 201 is emitted from the second light exit 267b (corresponding to the charge remover 1) (corresponding to the charge remover 3 in FIG. 1).

  As described above, the substrate 245 is provided with the light emitting element 244 that emits light for exposing the image carrier 201 as the light emitting element for exposure (see FIG. 8 and the like). Further, as shown in FIG. 19, on the substrate 245, the discharging light emitting elements 244 a for discharging the discharging light indicated by the optical path OP <b> 2 are arranged along the main scanning direction, that is, the arrangement direction of the light emitting elements 244 for exposure. . Unlike the light emitting element for exposure 244, the light emitting element for discharging 244a may be configured as a single light emitting element without arranging microelements. However, in consideration of the fact that the light-emitting element stops emitting light for some reason, it is desirable that the light-emitting element 244a for static elimination be composed of a plurality of light-emitting elements.

  The static elimination light emitting element 244 a is also sealed with the sealing glass 246 in the same manner as the exposure light emitting element 244. In the present embodiment, both the light-emitting element for exposure 244 and the light-emitting element for discharging 244a are sealed with a single sealing glass 246, but each light-emitting element may be sealed independently.

  Although the substrate 245 and the developing roller case 267 are in contact with each other in the drawing, they may be arranged with a slight gap if there are design restrictions or the like. Basically, the light emitted from the organic EL element constituting the light-emitting element 244a for static elimination is emitted isotropically, but since the luminance of the front surface of the light-emitting element is the highest, even if there is a gap between them, Most of the light is incident on the developing roller case 267.

  A light emitting element may be formed at a position indicated by P_lin_s of the substrate 245 (that is, the sub-scanning direction of the substrate 245), and light may be incident on the developing roller case 267 from a position indicated by P_lin_s. However, in this case, since the light propagation path becomes complicated, it is necessary to cause the light emitting element (organic EL element) to emit light with higher luminance in consideration of the influence of light attenuation. In such a case, it is desirable to drive the light emitting elements so as to be repeatedly turned ON / OFF intermittently rather than continuously lighting.

  Of course, it is desirable to perform intermittent driving also in the case where the above-described light-emitting element 244a for static elimination is arranged along the main scanning direction of the substrate 245.

  As shown in FIGS. 19 and 20, the developing roller 266 is fixed to the developing roller case 267 via eccentric cams 266a, developing roller shafts 266b, and polysliders (cam retaining members) 266c at both ends. . That is, the developing roller shaft 266b passes through unillustrated through holes at both ends of the developing roller case 267, and the polyslider 266c presses the eccentric cam 266a against both ends of the developing roller case 267 outside the case. The developing roller 266 and the developing roller case 267 are fixed integrally. In the present embodiment, the same configuration is employed in the combination of the four sets of developing rollers 266 and the developing roller case 267 (266Y, 267Y to 266K, 267K).

  Next, FIG. 23 shows a stirring unit 261 constituting a lower half of the developing unit 260 and a plurality of stirring units. As shown in FIGS. 21 to 23, the stirring unit 261 includes four sets of conveying screws 263a and 263b corresponding to the four sets of developing rollers 266 and the developing roller case 267 between the lower cover 261a and the upper cover 261b. Is housed and configured. The total number of conveying screws is eight.

  The lower cover 261a has a plurality of partition walls 261e formed in the longitudinal direction, and the conveying screws 263a and 263b are stored in a space partitioned by the partition wall 262e, and the first stirring unit 262a and the second stirring unit 262b is defined. A combination of the first stirring unit 262a and the second stirring unit 262b constitutes one stirring unit 262 corresponding to one developing roller. The stirring unit 261 is configured by integrally forming a plurality of stirring portions 262, and as a result, the number of parts of the developing unit can be reduced.

  As shown in FIG. 21, the conveying screws 263a and 263b are rotated in opposite directions by a drive gear 264 attached to the side surface of the lower cover 261a. As shown in FIG. 21, the toner supplied from outside is supplied. In the plane of the stirring unit 260 in opposite directions, the newly supplied toner and a carrier that is already in the stirring unit 261 and is made of, for example, ferrite (the toner and the carrier are combined into a developer). Are referred to as “circulate” in a plane and stirred. By this stirring, the toner and the carrier are rubbed against each other, and the toner is charged to a predetermined potential. In the present embodiment, negatively charged toner is used.

  FIG. 23 is an overall perspective view of the stirring unit 261 in which the upper cover 261b is attached to the lower cover 261a of FIG. The upper cover 261b has a toner inlet 261c for guiding the toner supplied from each of the yellow cartridge 70Y, the magenta cartridge 70M, the cyan cartridge 70C, and the black cartridge 70K shown in FIG. 1 through a tube (not shown). (261cY, 261cM, 262cC, 261cK) are formed. Further, a developer supply port 261d for guiding the stirred developer to the developing roller 266 is formed in the upper cover 261b.

  In this embodiment, as shown in FIGS. 24 and 25, the stirring unit 261 and the developing roller case 267 are connected via a foamed urethane sponge 268 as an adjustment member. The urethane foam sponge 268 serves as a seal that prevents the developer from scattering, and when the assembly of the stirring unit 261 and the developing roller case 267, that is, when the relative position needs to be changed, the both are shifted. Plays a role in absorbing. That is, the relative position between the developing roller case 267 and the agitating unit 261 and the relative position between the developing roller 266 and the agitating unit 261 can be changed via the urethane foam sponge 268.

  In this embodiment, as described above, two-component development is adopted as the development method. In the two-component development system, a magnet roller (not shown) having a predetermined magnetic pole is provided inside the developing roller 266, and a carrier (material is formed on the surface of the developing roller 266 by the magnetic force of the magnet roller. The toner is supplied to the image carrier 201 through the head of a magnetic material such as ferrite. Since the image density is determined by the amount of toner that is actually developed (that is, moved from the surface of the developing roller 266 to the image carrier 201), the position (distance) between the image carrier 201 and the developing roller 266 is high. Accuracy is required. Accordingly, it may be necessary to adjust the positional relationship between the image carrier 201 and the developing roller 266 at the final stage of manufacturing. In such a case, if the developing roller 266 and the agitating unit 261, that is, the developing roller case 267 and the agitating unit 261 are completely integrated and the relative position cannot be changed, both of them, that is, almost the entire developing unit 260 are moved. This necessitates a burden on the manufacturing process and makes it difficult to reduce the size of the image forming apparatus.

  However, in the developing unit 260 of the present embodiment, as described above, the relative position between the developing roller case 267 and the agitating unit 261, and the relative position between the developing roller 266 and the agitating unit 261, causes the foamed urethane sponge 268 that is an adjustment member to be adjusted. Therefore, after the position adjustment of the image carrier 201 and the developing roller 266 is performed with high accuracy (on the order of ± several 50 μm), the position of the stirring unit 261 is adjusted roughly (about ± 500 μm). It only has to be attached. Therefore, the burden on the manufacturing process is reduced, and the image forming apparatus can be downsized. Then, the developing roller case 267 and the stirring unit 261 whose positions have been determined are fixed with an adhesive or the like.

  Further, as described above, the developing roller 266 is fixed to the developing roller case 267 via the eccentric cams 266a, the developing roller shaft 266b, and the polyslider 266c at both ends thereof. Since the relative position between the developing roller case 267 and the stirring unit 261 can be changed, in the manufacturing process, the image carrier 201 and the stirring unit 261 are attached to predetermined portions, and then the position of the developing roller case 267 is changed. The distance (relative position) from the image carrier 201 can be set.

  The developing roller 266 is fixed by changing the positional relationship with the image carrier 201 through the action of the developing roller case 267. Such an action is achieved by the eccentric cam 266a that functions as a regulating member that regulates the positional relationship between the developing roller 266 and the image carrier 201. As shown in FIGS. 20B to 20D, the eccentric cam 266a has a slide hole 266d and a position fluctuation absorbing hole 266e. As shown in FIG. 3, protrusions 221f (see FIG. 7) formed on the first subframe 221 and the second subframe 222 are inserted into the slide holes 266d. Further, the position fluctuation absorbing hole 266e is larger in diameter than the developing roller positioning holes 221b and 222b shown in FIG. Further, the contact surface 266f is formed outside the slide hole 266d and substantially parallel to the slide hole. As shown in FIG. 4, the contact surface 266f is incorporated into the frame 220 as shown in FIG. Abutting against the metal fitting 201a. The intersection of the outer center line L1 indicates the center of the eccentric cam 266a when the contact surface 266f is used as a reference, and the intersection of the hole center line L2 indicates the center of the developing roller positioning holes 221b and 222b.

  With the above configuration, when the distance between the developing roller 262 and the image carrier 201 is adjusted in the manufacturing process, the eccentric cam 266a is rotated in the Rx direction in FIG. At this time, the eccentric cam 266a rotates in the R direction with the protrusion 221f inserted in the slide hole 266d. Then, since the intersection of the outer center line L1 and the intersection of the hole center line L2 are different, the eccentric cam 266a, the developing roller shaft 266b, and the developing roller 266 and the developing roller case 267 approach the image carrier 201 or carry the image. It is separated from the body, and the distance (relative position) from the image carrier can be adjusted.

  Assuming that one stirring unit 262 corresponding to one developing roller is configured by the combination of the first stirring unit 262a and the second stirring unit 262b, as shown in FIG. 262a and the second agitating unit 262b have a cylindrical configuration suitable for agitating the developer contained therein, and the first agitating unit 262a is opposite to the image carrier 201 with the developing roller 266 interposed therebetween. The second stirrer 262b and the first stirrer 262a are connected to each other substantially parallel to the arrangement direction of the plurality of developing rollers (horizontal direction in FIG. 18). Therefore, it is possible to reduce the size of the stirring unit in the direction perpendicular to the arrangement direction of the developing roller (up and down direction in FIG. 18).

  FIG. 28 shows another embodiment of the developing unit 260. In the present embodiment, unlike the example of FIG. 18, a part of the stirring unit (the first stirring unit 262 a in the example of FIG. 18) is adjacent to the image carrier at a position in the direction in which the plurality of image carriers 201 are arranged. Extends to the bottom of the body 201. In the example of FIG. 28, for example, the first stirring unit 262a of the image carrier 201K extends below the adjacent image carrier 201C at a position in the direction in which the plurality of image carriers are arranged. With this configuration, the stirring unit 262a extends to the lower part of the adjacent image carrier so that the region in the direction in which the plurality of image carriers 201 are arranged can be used effectively. In this configuration, when some structure is arranged on the downstream side of the transport path P (for example, in FIG. 1, when the discharge tray 40 approaches the print engine main unit 200), This is useful in cases where the overall layout of the image forming apparatus is changed.

  In the example of FIGS. 18 and 28, the first stirring unit 262a (263a) and the second stirring unit 262b (263b) are mounted substantially horizontally, and there is no inclination when the developer is stirred. The developer can be easily stirred.

  Although the present embodiment has been described based on the configuration in which the developing unit 260 is disposed below the image carrier 201, the positional relationship may be changed. For example, the top and bottom of the configuration described above may be replaced, and the developing unit 260 may be disposed above the plurality of image carriers 201. However, in this case, it is necessary to arrange a restricting means for restricting the supply of the developer from the stirring unit 262 to the developing roller 266 that is the developing unit. Further, the above-described configuration may be rotated by 90 °. In this case, since the first stirring unit 262a and the second stirring unit 262b constituting the stirring unit 262 are in a vertical relationship, the developer conveyed by one stirring unit (for example, the first stirring unit 262a) A means for ensuring the conveyance capability is required in a portion (a portion where the developer is U-turned in FIG. 21) to be passed to another stirring portion (for example, the second stirring portion 262b). For example, a magnet or the like may be disposed in the U-turn portion, and the developer to be conveyed may be conveyed to the upper stirring unit. Further, regarding the relationship between the developing unit 260 and the image carrier 201, a plurality of image carriers 201 may be arranged obliquely below the developing unit 260.

  Further, when grasping the image forming apparatus 1 of the present embodiment from another viewpoint, when attention is paid to the relationship between the developing unit 260 and the exposure unit 240 in FIGS. 8 to 12, the support member 241 of the exposure unit 260 serves as the developing roller. 266 and the stirring unit 262 (stirring unit 261). That is, as shown in FIG. 18 and FIG. 28, the developing unit 260 penetrates the support member 241 constituting the exposure unit 240 corresponding to each developing roller 266 and roller case 267 as shown by the dotted line H. A through hole is provided for this purpose. With this configuration, the support member 241 that supports the light emitting element array 242 is provided between the developing roller 266 and the stirring unit 262, and the stirring unit positions the exposure unit 240 that exposes the image carrier 201. Therefore, the image forming apparatus 1 can be downsized. This through hole is omitted in FIGS.

  Further, in the present embodiment, a developing blade 248 that adjusts the amount of developer attached to the developing roller 266 is fixed to the support member 241 (not shown in FIGS. 8 to 12). The developing blade 248 is usually formed by bending a metal plate made of SUS or the like at a predetermined angle, and is fixed to the main plane 241b of the support member 241 using an adhesive, a screw or the like. With this configuration, the developing blade 248 can be fixed using the support member 241 of the exposure unit 240 without using extra members.

  The developing blade 248 may be fixed not to the support member 241 but also to the first sub-frame 221 and the second sub-frame 222 as positioning members. That is, in FIG. 7, the developing blade 248 is inserted from the developing blade insertion port 221g formed at the lower end of the subframe 221, and the screw is inserted into the developing blade mounting screw hole 221h formed adjacent to the developing blade insertion port 221g. Then, the developing blade is fixed. Although not shown, the developing blade fixed by the screw hole is provided with a mounting hole 248a at a position corresponding to the developing blade mounting screw hole 221h (see FIG. 26), and this mounting hole 248a is formed on the developing blade 248. In order to adjust the mounting position, it is set slightly larger.

  During assembly of the above-described embodiment, the developing blade 248 is usually temporarily fixed to the first subframe 221 and the second subframe 222, and the position of the developing blade 248 is adjusted in the adjustment process, and thereafter Final fastening and final fixing with adhesive. In the case where the developing blade 248 is fixed to the support member 241, it is fixed through the same process. In FIG. 26, the subframe and the exposure unit above the stirring unit 261 are omitted for convenience of illustration.

  Note that the developing blade 248 may be provided on the upper cover 261b of the stirring unit 261. In this case, the process of attaching the developing blade 248 is provided in the manufacturing process of the developing unit 260, so that the function sharing becomes clearer from the viewpoint of subsystemization, which is advantageous in terms of quality management in the manufacturing process. .

  Further, the developing unit of this embodiment is further provided with a density detection sensor 265 (265Y to 265K) that detects the density of the developer stored in the stirring unit 262. As shown in FIGS. 18 and 27 (b), the concentration detection sensor 265 is attached to the bottom of the stirring unit, and corresponds to the B part of FIG. That is, the density detection sensor 265 is located in another path separated from the path of the developer introduction port 261c (FIG. 23) by the partition wall 261e, and the density detection sensor 265 adjusts the density in a state where the toner and the carrier are sufficiently mixed. Can be measured. Further, since it is near the developer inlet 261c even in another route, the accuracy of the amount of developer to be replenished can be improved.

  As shown in FIG. 29, the density detection sensor 265 has a protrusion-shaped developer mixture ratio detection unit 265a attached to the bottom of the stirring unit. The developer mixing ratio detection unit 265a detects the mixing ratio (concentration) of the carrier and toner in the conveyance path of the stirring unit. When the carrier amount is large, the output voltage increases. When the carrier amount is small, the output voltage increases. (See FIG. 29B).

  With this configuration, it is possible to detect the concentration of the developer accommodated in the agitation unit. For example, when the amount of toner accommodated in the agitation unit decreases, it is possible to appropriately supply the toner. High image formation can be performed. Further, the density detection sensor 265 is attached to the bottom of the agitation unit, and the enlargement of the developing unit due to the installation of the density detection sensor 265 can be suppressed.

  In the above example, the developing roller 266 is used as the developing unit. However, with such a configuration, there is a concern that a sufficient amount of developer cannot be supplied to the developing roller when the agitating unit and the developing roller are separated considerably. In such a case, the developer may be supplied to the image carrier 201 via a belt instead of the developing roller 266, and such a configuration can be applied to the developing unit. Accordingly, the configuration of the developing unit is not limited to the developing roller as long as the developer can be appropriately supplied to the image carrier 201.

(Description of transfer unit)
Next, the transfer unit 280 will be described with reference to FIGS. As described with reference to FIG. 1, the transfer unit 280 plays a role of transferring the toner image on the image carrier 201 onto the recording paper R as a transfer material. The transfer unit 280 is provided on the conveyance path P of the recording paper R as shown in FIG. A conveyance guide 206 is attached to the lower surface of the transfer unit 280 and defines a conveyance path P together with the transfer material pressing roller 224.

  The transfer unit 280 includes a transfer frame 281, a wire guide 283, and a transfer wire 282. Wire guides 283 (283a, 283b) are attached to both ends of the transfer frame 281. A single transfer wire 282 made of, for example, tungsten is wound around a wire roller 284 that is rotatably attached to the wire guide 283. However, the transfer frame 281 is stretched inside the plane. The wire roller 284 is provided with a height adjustment boss 287, and the height of the wire (distance between the wire and the image carrier) can be adjusted by operating the boss. Accordingly, it is possible to easily adjust the operation of the transfer unit 280 on the image carrier in the manufacturing process.

  Further, a high voltage terminal 286 and a tension spring 285 for connecting a transfer bias, which is a high voltage potential supplied from the controller 50, to the transfer wire 282 are attached to the end of the transfer wire 282. A predetermined tension is applied to the transfer wire 282 by the high voltage terminal 286 being stopped outside the transfer frame 281 in a state where the tension spring 285 is pulled.

  The transfer method of this embodiment is called a so-called corotron method, in which corona discharge is performed from a transfer wire 282 to transfer a toner image formed on the photosensitive member 201 onto the recording paper R. Discharge should be made individually corresponding to each of the image carriers 201Y to 201K, and it is necessary to prevent the electric field formed by the discharge from affecting the transfer on the adjacent image carriers. Therefore, a partition plate 281a is formed on the transfer frame 281 and partitions a space including the transfer position of each image carrier. In FIG. 14, the space including the wire 282 corresponding to the transfer position PT1 and the space including the wire 282 corresponding to the transfer position PT2 are partitioned by the partition plate 281a, and one wire portion is the other. The influence on the transfer position is suppressed.

  FIG. 31 shows an example in which the transfer unit 280 has a recording paper R adsorption function. An intake fan 271 is disposed directly above the transfer unit 280 via an intake duct 272. When the intake fan 271 is activated, an adsorption force is applied to the recording paper R passing through the conveyance path P through the intake hole 272a of the intake duct 272, and the recording paper R is in a state where a negative pressure is applied to the conveyance guide 206 side. Then, it passes through the conveyance path P. With such an action, when there is no transfer material pressing roller 224, the deflection amount of the recording paper R can be made virtually zero, and the transfer position deviation can be prevented.

(Explanation of static elimination function of exposure unit)
Finally, an application example of the exposure unit 240 of the present embodiment will be described with reference to FIG. Although the configuration of the exposure unit 240 has already been described, in the present embodiment, an example in which a function of a static eliminator for removing extra charge of the image carrier 201 is added to the exposure unit 240, particularly the mode shown in FIG. Different embodiments will be described.

  The light-emitting elements 244 of the light-emitting element array 242 of the exposure unit 240 described above are used as the light-emitting elements 244 for exposure that form the electrostatic latent image on the image carrier 201, that is, the original role of the exposure unit 240. Is. In addition to this configuration, in the present embodiment, a charge-removing light-emitting element 244a for discharging charges on the image carrier 201 is provided on the same substrate 245 as the substrate 245 on which the light-emitting element 244 for exposure is formed. With this configuration, the light-emitting element for charge removal is provided on the same substrate together with the light-emitting element for exposure, so that the number of parts attached to the image forming apparatus 1 and the cost can be reduced, and the image forming apparatus 1 can be downsized.

  In particular, in this embodiment, the light emitting element for exposure and the light emitting element for charge removal are made of organic EL, and the drive circuit and the organic EL element can be integrally formed on the substrate. And cost reduction. The same effect can be expected when the light emitting element is composed of LEDs.

  As shown in FIG. 32 (b), the light-emitting element 244a for static elimination has both ends of the light-emitting element array 242 formed on the substrate 245, and further on the extension line of the light-emitting element array 242, that is, the arrangement direction of the light-emitting element elements 244 for exposure. It is arranged on the extension line. In this embodiment, the light guide 205 is used to guide the light emitted from the light-emitting element 244a for static elimination to each image carrier. The light guide 205 is made of a transparent material such as acrylic resin (light transmissive resin) or glass, or a light transmissive material, and guides light emitted from the light-emitting element 244a for discharging to a predetermined position. With this configuration, the light-emitting light-emitting element 244 and the light-emitting light-emitting element 244a may be arranged in the same arrangement direction on the substrate 245. In a series of organic EL element manufacturing processes, for example, a photomask for forming electrodes, Only by providing a region corresponding to the light-emitting element 244a for static elimination, it can be formed simultaneously with the light-emitting element for exposure. For this reason, the manufacturing cost of the static elimination light emitting element 244a is substantially zero. In addition, the number of parts attached to the image forming apparatus and the cost can be reduced, and the image forming apparatus can be downsized.

  As shown in FIGS. 19B and 32B, the static elimination light emitted from the static elimination light emitting element 244a travels along the optical path OP2, and the developing roller case 267 configured by a part of the light guide 205 is the first one. The light is emitted from the first light emission port 267a and the second light emission port 267b. The first light exit port 267a emits a neutralizing light before transfer of the toner image onto the recording paper R (corresponding to the neutralizer 1 in FIG. 1), and the second light exit port 267b receives an image carrier. The neutralizing light after cleaning by the brush cleaner 204 of 201 is emitted (corresponding to the static eliminator 3 in FIG. 1). That is, the light guide 205 plays a role of guiding the light emitted from the light-emitting element 244 a for discharging to a plurality of different parts of the image carrier 201. With this configuration, since the image carrier 201 is neutralized at a plurality of different portions, an independent neutralizer is not required, and the image forming apparatus can be made smaller.

  More specifically, a charging roller 203 as a charger, an exposure unit 240, a developing unit 260, and a transfer unit 280 are provided around each of the plurality of image carriers 201Y to 201K. Then, the light guide 205 transfers the light emitted from the light-emitting element 244a for static elimination to the plurality of image carriers between the developing unit 260 and the transfer unit 280 through the first light emission port 267a. The light is guided from the second light exit 267b between the unit 280 and the charging roller 203. Therefore, even in a tandem type image forming apparatus that has a plurality of image carriers and forms a color image, the number of parts and cost attached to the image forming apparatus can be reduced, and the image forming apparatus can be downsized. .

  In particular, in the present embodiment, the light guide 205 is constituted by an integral member, and the light emitted from the static elimination light emitting element 244a is guided to each of the plurality of image carriers 201Y to 201K only by the integral member. ing. With this configuration, the light guide body 205 that emits light from the light-emitting element 244a for static elimination is realized with a single component for a plurality of image carriers, thereby reducing the number and cost of components attached to the image forming apparatus. Therefore, it is possible to reduce the size of the image forming apparatus.

  Note that a plurality of light-emitting elements 244a for static elimination may be provided on the substrate 245 in the vicinity of the two places illustrated in FIG. It is desirable to configure these light-emitting elements 244a for static elimination to correspond to different electrodes so that ON / OFF can be selectively controlled from the outside. Since the TFT circuit is formed on the substrate 245 as already described, such a selective switching circuit can be easily configured. The purpose of the charge eliminating step is to expose the photosensitive member, which is an image bearing member, to light and thereby attenuate the surface potential uniformly. Therefore, a very large amount of emitted light is required for the charge eliminating light emitting element 244a. However, it is known that when an organic EL element emits light with a large amount of light, the light emission efficiency decreases with time and the light emission luminance decreases. Therefore, as described above, a plurality of charge-removing light-emitting elements 244a are prepared in advance on the substrate 245, and the charge-removing light-emitting elements 244a are switched and used based on the accumulated light emission time measured by the controller 50 (FIG. 1), for example. This makes it possible to always secure the necessary light quantity. In addition, a photosensor (not shown) configured by a photodiode or the like is provided in a part of the light guide 205, and the light-emitting element 244a for static elimination is switched or the light-emitting element 244a for static elimination is switched according to the output of the photosensor. You may make it control the drive current which drives this.

  The light guide 205 needs to efficiently propagate the light emitted from the light-emitting element 244a for static elimination. As shown in the drawing, the light guide 205 has a relatively complicated shape, and therefore, when it is composed of only a single material, there is a problem in terms of light transmission efficiency. Therefore, it is preferable that the light guide 205 is made of a predetermined glass material, and the refractive index of light decreases toward the outer surface by ion exchange. As a result, the light propagating through the light guide 205 is propagated in a mode similar to so-called total reflection due to the difference in the refractive index inside the light guide 205, and extremely high transmission efficiency can be secured. .

  In addition, the entire inner surface of the light guide 205 may be processed with the exception of the first light exit 267a and the second light exit 267b (see FIG. 19). In this case, since the light propagates through the light guide 205 by specular reflection, the transmission efficiency is lowered, but there is an advantage that it can be processed at a low cost.

  Further, a light source (a backlight light source in a liquid crystal display device or an indicator indicating the status of the image forming device) is provided in the vicinity of the light-emitting element 244a for discharging or other portions. A light-emitting element for display serving as a light source can also be provided. With this configuration, not only the light-emitting light emitting element 244a but also the display light-emitting element are provided on the same substrate as the light-emitting element for exposure, so that the image forming apparatus can be downsized. At this time, the light emitted from the display light emitting element may be guided to the display unit 60 using another light guide. With this configuration, the number of parts and cost can be further reduced, and the image forming apparatus can be reduced in size.

  Although various embodiments of the present invention have been described, the present invention is not limited to the matters shown in the above-described embodiments, and those skilled in the art may modify or apply the description based on the description of the specification and well-known techniques. The present invention is intended to be included in the scope for which protection is sought.

  As described above, according to the present invention, an exposure unit and an image forming apparatus capable of reducing the number of parts of the image forming apparatus and reducing the size are provided.

Conceptual diagram showing the operation of the image forming apparatus Sectional drawing of the image forming apparatus of one Embodiment of this invention Perspective view of the print engine main unit (A) is a perspective view of a state where a transfer unit of the print engine main unit is removed, (b) is a front view of the same state, and (c) is a side view of the same state. Cross section of the print engine main unit Perspective view of the print engine main unit cut at the center in the width direction Perspective view of the frame of the print engine main unit (A) is a perspective view of an exposure unit, (b) is a sectional view of the exposure unit of (a). The figure explaining the positioning method of a board | substrate at the time of attaching a light emitting element substrate to the support member of an exposure unit (A) is a figure explaining the positioning method of the board | substrate at the time of attaching a light emitting element board | substrate to the supporting member of an exposure unit using the front view of an exposure unit, (b) is sectional drawing of the exposure unit of (a). Illustration using (A) is a perspective view of other embodiment of an exposure unit, (b) is sectional drawing of the exposure unit of (a). (A) is a perspective view of still another embodiment of the exposure unit, (b) is an enlarged view of an upper portion of the exposure unit of (a), and (c) is a front view of the exposure unit of (a). (D) is a sectional view taken along line AA of the exposure unit of (c). Conceptual diagram explaining the occurrence of misalignment of transfer position due to deflection of recording paper 1 is a conceptual diagram of a conveyance mechanism of an image forming apparatus according to an embodiment of the present invention. (A) is an overall perspective view of the fixing unit front guide, and (b) is an enlarged view of a dotted line A portion of FIG. The figure which shows the period fluctuation of the peripheral speed of the registration roller It is a figure which shows the outer periphery bearing structure of a registration roller, (a) is an enlarged view of the edge part of the registration roller with which the bearing was mounted | worn, (b) is a perspective view of a bearing. Side view specifically showing the development unit in the print engine main unit (A) is a perspective view of a developing roller and a developing roller case, and (b) is a sectional view. Explanatory drawing of an eccentric cam etc. that functions as a regulating member at the end of the developing roller The perspective view which shows the conveyance screw accommodated in the lower cover of the stirring hot water unit of a developing unit, and an inside Perspective view of conveying screw FIG. 21 is a perspective view of a completed stirring unit by attaching the upper cover to the state shown in FIG. Side view showing a state where the upper developing roller case and the lower stirring unit are attached to or separated from each other in the developing unit In the developing unit, a perspective view showing a state in which the upper developing roller case and the lower stirring unit are attached to or separated from each other Perspective view of completed development unit (A) is sectional drawing of the image development unit along the CC line of FIG. 26, (b) is a bottom view of the completed image development unit. Side view of another embodiment of development unit (A) It is a perspective view of a density | concentration detection sensor, (b) is a graph which shows the relationship between printing engine operating time and density | concentration detection sensor output (A) is a perspective view of the transfer unit, (b) is a back view of the end of the transfer unit, a cross-sectional view (A) is a perspective view of a transfer unit having an intake fan, (b) is a sectional view of the transfer unit, and (c) is a back view of the transfer unit. (A) is a perspective view of the exposure unit which has a light guide, (b) is sectional drawing along the AA of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Housing | casing 20 Paper cassette 30 Main body frame 40 Discharge tray 50 Controller 60 Display part 70 Cartridge 100 Print engine 110 Paper feed roller 130 Fixing device 131 Pressure roller 132 Heating roller 140 Discharge roller 200 Print engine main unit 201 Image Carrier 202 Registration roller 203 Charging roller 204 Brush cleaner 205 Light guide 206 Transport guide 220 Frame 221 First subframe 222 Second subframe 223 Fixing device front guide 224 Transfer material pressing roller 240 Exposure unit 241 Support member 242 Light emission Element array 243 Screw 244 Light emitting element 245 Substrate 246 Sealing glass 247 Conspicuous lens 248 Developing blade 260 Developing unit 261 Agitation unit 262 Agitation unit 263 -Menu 264 driving gear 265 concentration detecting sensor 266 developing roller 267 developing roller case 268 foam urethane sponge 269 body mounting plate 271 suction fan 272 intake duct 280 the transfer unit 281 the transfer frame 282 transfer wire 283 wire guide 284 Waiyakoro 285 tension spring 286 high-voltage terminal

Claims (14)

An exposure unit provided in an image forming apparatus having an image carrier and capable of irradiating the image carrier with light,
A light emitting device for exposure provided on a substrate and forming an electrostatic latent image on the image carrier;
A light-emitting element for static elimination provided on the substrate for neutralizing charges of the image carrier;
An exposure unit comprising: The exposure unit according to claim 1,
The exposure unit in which the light-emitting element for exposure and the light-emitting element for charge removal are organic electroluminescence elements. The exposure unit according to claim 1 or 2,
The light-emitting element for charge removal is an exposure unit arranged on an extension line in the arrangement direction of the light-emitting elements for exposure. The exposure unit according to any one of claims 1 to 3,
An exposure unit further comprising a display light emitting element provided on the substrate and serving as a light source of a display unit provided in the image forming apparatus. The exposure unit according to any one of claims 1 to 4,
A light guide that guides the light emitted from the light-emitting element for static elimination to the image carrier;
An image forming apparatus comprising: The image forming apparatus according to claim 5, wherein
The light guide is an image forming apparatus that guides light emitted from the light-emitting element for charge elimination to a plurality of different portions of the image carrier. The image forming apparatus according to claim 5, wherein:
A display unit;
The exposure unit further includes a display light emitting element provided on the substrate and serving as a light source of a display unit provided in the image forming apparatus,
The light guide is an image forming apparatus that guides light emitted from the display light emitting element to the display unit. The image forming apparatus according to any one of claims 5 to 7,
Comprising a plurality of the image carriers,
The light guide is an image forming apparatus that guides light emitted from the light-emitting element for discharging to each of the plurality of image carriers. The image forming apparatus according to claim 8, wherein
Further comprising a charger, an exposure unit, a development unit, and a transfer unit provided around each of the plurality of image carriers,
The light guide guides the light emitted from the charge-removing light emitting element between the developing unit and the transfer unit and between the transfer unit and the charger for the plurality of image carriers. Image forming apparatus. The image forming apparatus according to claim 8 or 9, wherein
The image forming apparatus, wherein the light guide is integrally formed and guides light emitted from the light-emitting element for discharging to each of the plurality of image carriers. The exposure unit according to claim 1 or 2,
The light-emitting element for charge removal is an exposure unit arranged along the arrangement direction of the light-emitting elements for exposure. The exposure unit according to claim 11,
An exposure unit in which the light-emitting element for charge removal is composed of a single organic EL element. The exposure unit according to claim 11,
An exposure unit in which the light-emitting element for charge removal is composed of a plurality of organic EL elements. The exposure unit according to any one of claims 1 to 4,
A developing roller for developing a latent image on the image carrier exposed by the exposure unit;
A developing roller case covering a part of the developing roller;
Have
An image forming apparatus configured to remove light from the image carrier by guiding light emitted from the light-emitting element for charge removal by the developing roller case.

Images