JP4609049B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an apparatus capable of forming a high quality image by attaching and transferring toner at an equal density on an image forming surface.

  2. Description of the Related Art Conventionally, an electrophotographic recording type image forming apparatus that exposes and forms an electrostatic latent image on the surface of a carrier made of a photoreceptor is known. In this image forming apparatus, the electrostatic latent image is developed with toner. The toner image on the surface of the carrier carried in this manner is transferred to a recording medium such as recording paper to form an image. The electrostatic latent image is developed by rotating a developing roller facing the surface of the carrier and transferring and adhering toner on the outer peripheral surface of the roller. Then, the toner is supplied by the supply roller rotating in the toner storage space being pressed and rotated.

  An image forming apparatus employing this electrophotographic recording system forms an image by transferring and fixing a toner image obtained by developing an electrostatic latent image on the surface of a carrier to a recording medium as it is. The thickness of the toner on the outer peripheral surface of the developing roller for developing the image greatly affects the density of the image on the recording medium. For this reason, this image forming apparatus is provided with a regulating member that makes the thickness of the toner supplied and adhered on the outer circumferential surface of the developing roller constant, and this regulating member is parallel to the outer circumferential surface of the developing roller. The thickness is regulated to be constant by scraping off the toner adhering to the outer peripheral surface.

  Here, since both ends of the developing roller are rotatably supported, when the developing roller is pressed by a member parallel to the axial direction, the central portion of the developing roller is curved so as to escape, and the outer peripheral surface thereof It will bend and bend also with respect to the regulating member which should be installed in parallel to. In order to reduce the weight of the developing roller as a result of progress in recent improvements in metal materials, for example, this bending tendency has been changed from, for example, iron to aluminum, and from a cylindrical (solid) and highly rigid structure to a cylindrical shape. (Hollow) and increased with changing to a structure with low rigidity.

  This bending of the developing roller makes it difficult to make the thickness of the toner adhered on the outer peripheral surface uniform by the regulating member, and makes the density of the toner image obtained by developing the electrostatic latent image on the surface of the carrier uniform. You can't do it. As a result, when the toner image is transferred and fixed as it is on the recording medium, the non-uniform toner thickness on the outer peripheral surface of the developing roller reduces the quality of the image formed on the recording medium.

For this reason, in an image forming apparatus that employs an electrophotographic recording method, a regulating member is formed in a convex shape or pressed on the central portion of the regulating member so as to follow the curvature of the outer peripheral surface of the developing roller. Has been proposed to make the thickness of the toner on the outer peripheral surface uniform (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 6-110311

  However, in such a conventional image forming apparatus, the toner adhering to the outer peripheral surface of the regulating member is pressed against the outer peripheral surface of the developing roller by the flat portion on the rear end side with respect to the front end edge of the regulating member. Since the tip edge of the regulating member protrudes away from the pressure contact position with the outer peripheral surface of the developing roller in the tangential direction, The layer thickness of the toner that enters between the outer peripheral surfaces increases.

  Here, the developing roller bends due to the pressure contact with the supply roller, but the restricting member can only be brought into pressure contact with the outer peripheral surface of the developing roller at a position shifted from the pressure contact position, and the developing roller has a curved outer peripheral surface. It is difficult to align the regulating member with high accuracy. Therefore, even when the regulating member is curved as in the image forming apparatus described in the above-mentioned document 1, the developing roller is curved with respect to the outer circumferential surface of the developing roller that is curved by the pressure contact of the supply roller. From the slightly different direction, the central part of the curving regulation member approaches (see FIG. 5A).

  As a result, the central portion of the leading edge of the regulating member protrudes away from the outer peripheral surface of the developing roller in the tangential direction from both end portions, so that the toner layer thickness is increased. The toner thickness on the outer peripheral surface cannot be effectively made uniform in the axial direction.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of forming a high-quality image by realizing uniform toner thickness on the outer peripheral surface of a developing roller with a simple structure. And

  According to a first aspect of the present invention, there is provided an image forming apparatus for carrying a toner image on which an electrostatic latent image based on image data is formed and developing the electrostatic latent image, and the surface of the carrier And a developing device for developing the electrostatic latent image by selectively adhering the toner to the electrostatic latent image, and forming the image by transferring and fixing the toner image on the surface of the carrier onto the recording medium. In the image forming apparatus, the developing device includes a container for storing toner, a developing roller that adheres the toner on the outer peripheral surface to the carrier by rotating the outer peripheral surface of the carrier without contacting the carrier, and A supply roller that rotates the outer peripheral surfaces of the developing roller against each other by pressing the developing roller and supplies toner in the container to the outer peripheral surface of the developing roller, and a flat portion on the rear end side from the edge on the front end side. The outer peripheral surface of the developing roller by being pressed against A regulating member that scrapes off the toner that rotates so as to adhere to the tip end at the leading edge to make the thickness of the toner constant, and the regulating member is a tangential direction of the outer peripheral surface of the developing roller. This is characterized in that there is a difference in the amount of protrusion between both ends and the center of the leading edge.

  In the present invention, the leading edge of the regulating member has a difference in the amount of protrusion in the tangential direction from the pressure contact position with the outer peripheral surface of the developing roller between the both end portions and the central portion, so that the leading edge is scraped at the leading edge. It is possible to adjust the layer thickness of the toner that enters between the outer peripheral surface of the developing roller after dropping and the axial direction of the developing roller. Therefore, for example, by designing (adjusting) the amount of protrusion of the leading edge of the regulating member in accordance with the deflection of the developing roller, the thickness of the toner entering between the regulating member and the outer peripheral surface of the developing roller can be reduced. It can be made uniform in the axial direction.

  According to a second aspect of the image forming apparatus for solving the above-described problem, in addition to the specific matter of the first aspect, the regulating member has a gap formed between a leading edge and an outer peripheral surface of the developing roller. The leading edge is projected in the tangential direction of the outer peripheral surface of the developing roller so as to be uniform in the axial direction of the developing roller.

  In the present invention, the protruding amounts of the both ends and the center of the leading edge are adjusted so that the gap between the leading edge of the regulating member and the outer peripheral surface of the developing roller is uniform in the axial direction. Accordingly, the toner on the outer peripheral surface of the developing roller is scraped off at the front end edge of the regulating member, and the toner having a uniform layer thickness from the axially uniform gap defined between the front end edge and the outer peripheral surface. Can be entered.

  According to a third aspect of the image forming apparatus for solving the above-described problems, in addition to the specific matters of the first or second aspect, the center portion of the restricting member recedes toward the rear end side from both end portions of the front end side edge. It is formed in a curved shape.

  In the present invention, the central portion of the leading edge of the regulating member is retracted from both end portions to form a gap with the outer peripheral surface of the developing roller. Here, the developing roller is curved in a direction in which the supply roller is pressed and separated, while the regulating member is rotated so that the toner on the outer peripheral surface of the developing roller is scraped off at the leading edge. Is set to For this reason, when the front end side edge of the regulating member is linear while the developing roller is curved, the central portion thereof is substantially the both end portions with respect to the tangential direction of the outer peripheral surface of the curved developing roller. Therefore, the toner left scraped thicker than between both end portions enters between these central portions, and the layer thickness in the axial direction cannot be made uniform. However, according to the present invention, when the layout is made such that the direction in which the central portion of the leading edge of the regulating member recedes and the direction in which the developing roller curves substantially coincides, the central portion of the regulating member. Is retracted in substantially the same direction as the outer peripheral surface of the curved developing roller, and the central portion and both end portions protrude substantially to the same extent with respect to the tangential direction of the outer peripheral surface. Therefore, the toner scraped off to the same extent as that between the both end portions can enter between the regulating member and the central portion of the developing roller, and the toner layer thickness on the outer peripheral surface of the developing roller can be used as an axis. Uniform in the direction.

  According to a fourth aspect of the image forming apparatus for solving the above-described problems, in addition to the specific matters of the first to third aspects of the invention, the restricting member is located at a central portion rather than at both ends of the outer peripheral surface of the developing roller. The pressure contact pressure is set high.

  In the present invention, the central portion of the leading edge of the regulating member is curved and pressed against the outer peripheral surface of the developing roller. Here, the developing roller is curved in a direction in which the supply roller is pressed and separated, while the regulating member is rotated so that the toner on the outer peripheral surface of the developing roller is scraped off at the leading edge. Is set to For this reason, when the front end side edge of the regulating member is linear while the developing roller is curved, the central portion thereof is substantially the both end portions with respect to the tangential direction of the outer peripheral surface of the curved developing roller. Therefore, the toner left scraped thicker than between both end portions enters between these central portions, and the layer thickness in the axial direction cannot be made uniform. However, in this invention, when the layout is made so that the direction in which the central portion of the leading edge of the regulating member is curved and the direction in which the developing roller curves are substantially coincident, the central portion of the regulating member. By adjusting the amount of protrusion with respect to both ends by retreating in substantially the same direction as the outer peripheral surface of the developing roller while being curved toward the developing roller and deforming along the outer peripheral surface, The shape of the leading edge with respect to the developing roller can be adjusted by the curving and protruding amount of the regulating member, and the thickness of the toner layer to be scraped according to the shape of the device can be made uniform in the axial direction with high accuracy. Can do. Therefore, it is possible to allow the toner left to scrape between the regulating member and the central portion of the developing roller to have the same thickness as that between the two end portions with high accuracy, and the toner layer thickness on the outer peripheral surface of the developing roller. Can be made uniform with high accuracy in the axial direction.

  As described above, according to the present invention, the amount of protrusion for projecting the front end edge of the restricting member is merely scraped at the front end side of the restricting member only by making a difference such as retreating the central portion with respect to both end portions. It is possible to adjust the axial thickness of the toner on the outer peripheral surface of the developing roller that enters between each other. Therefore, the thickness of the toner on the outer peripheral surface of the developing roller can be made uniform with a simple structure, and the electrostatic latent image on the surface of the carrier can be developed with high quality by the toner. At this time, at the same time, the central portion of the leading edge of the regulating member may be curved (pressure contact) toward the outer peripheral surface of the developing roller. In this case, the degree of curving of the regulating member is adjusted to the developing roller, The toner layer thickness on the outer peripheral surface of the developing roller can be adjusted more accurately by the protruding amount of the leading edge of the regulating member.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described based on the drawings. 1 to 4 are diagrams showing an embodiment of an image forming apparatus according to the present invention.

  1 and 2, the image forming apparatus creates and outputs an image such as a character. For example, the image forming apparatus is used by being connected to a personal computer PC, and the control unit 10 connected to the personal computer PC has a paper sheet. By comprehensively controlling the conveyance device 20 and the image recording device 30, an image is formed on a recording sheet (recording medium) and printed out.

  The control unit 10 includes a controller unit 11 and an engine control unit 12 which are constructed on a circuit board mounted in the apparatus main body. These units perform various data processing controls and various parts of the apparatus according to a program prepared in advance. The drive control is executed.

  Briefly, the controller unit 11 executes various processing procedures according to a processing program stored in a memory by a CPU (not shown), thereby various information such as a print command with a printer driver of the personal computer PC. Are received, and image data such as text to be formed by printing on a recording sheet is received and temporarily stored in a memory (not shown). The controller unit 11 is so-called RGB data of red (R), green (G), and blue (B) because the image data (image information signal) received from the personal computer PC is yellow (which can be printed). Y), magenta (M), cyan (C), and black (K) are converted into image data of so-called YMCK data, read out from the memory, and transferred to the engine control unit 12.

  In the engine control unit 12, the CPU 13 receives image data, for example, in units of pages from the controller unit 11 according to a control program stored in the ROM 14, temporarily stores it in the main body memory 15, and uses the RAM 16 as a work area. While exchanging various types of information between the paper transport device 20 and the image recording device 30, an image based on the image data is formed on the recording paper. At this time, when executing this image formation control, the CPU 13 causes each unit of the apparatus to operate optimally by measuring various processing times with a built-in timer function (timer) 13a.

  In FIG. 2, the I / O interface 17 connects the controller unit 11, the sheet transport device 20, the image recording device 30, and the engine control unit 12 so that various types of information can be exchanged. The D / A converter 18 and the A / D converter 19 are configured so that the engine control unit 12 can process various information exchanged between the controller unit 11, the sheet conveying device 20, and the image recording device 30, respectively. The digital signal (D) is converted into an analog signal (A), or the analog signal is converted into a digital signal.

  In addition to the paper cassette 21, the paper discharge table 22, the pickup roller 23, the transport roller pair 24, the registration roller pair 25, the switching roller pair 26, the paper discharge roller pair 27, and the reverse roller pairs 28 and 29. The intermediate transfer belt 34, which is also a component of the image recording apparatus 30, the transfer roller 35, and the fixing roller pair 36 are constructed. The sheet conveying apparatus 20 separates and conveys a plurality of recording sheets stacked in the sheet cassette 21 one by one and feeds them to the image recording position P1 by the image recording apparatus 30. After image data such as characters received on one side or both sides is recorded and formed, this image-formed recording paper is carried out of the apparatus and stacked on the paper discharge table 22.

  Briefly, the pickup roller 23 pulls out the recording sheet by rotating against the recording sheet loaded on the lifting plate 21a in the sheet cassette 21 and cooperates with a separating means (not shown). The sheets are separated one by one and fed to the conveyance path f. The conveyance roller pair 24 nips and conveys the recording paper and corrects the skew by abutting the front end against the nip portion of the registration roller pair 25 on the downstream side. The registration roller pair 25 nipping and feeding the recording sheet to the image recording position P1 so as to synchronize with the operation of the image recording apparatus 30.

  At the image recording position P1, the intermediate transfer belt 34 and the transfer roller 35 are transported by rotating while sandwiching the fed recording paper, and the image is formed in an image recording apparatus 30 described later. The toner image primarily transferred to the intermediate transfer belt 34 is secondarily transferred to one side of the recording paper to record and form an image. Further, the fixing roller pair 36 rotates while sandwiching the recording paper, thereby conveying the recording paper further downstream and fixing the image on the recording paper.

  Thereafter, the switching roller pair 26 and the discharge roller pair 27 carry the recording paper from the fixing roller pair 36 onto the discharge table 22 and stack it. As a result, the recording sheet is fed to the image recording formation position P1 by the image recording apparatus 30 with one side being the image recording formation surface, and is formed on one side and then discharged onto the discharge table 22. The

  At this time, when the engine control unit 12 has instructed the duplex control mode for forming an image on both sides of the recording paper, the paper transport device 20 records the paper discharge roller pair 27 carried onto the paper discharge table 22. After temporarily stopping at a position where the trailing edge of the sheet is sandwiched, the recording sheet on which an image is recorded on one side is sent out to the reverse path r by being reversely driven together with the switching roller pair 26.

  Thereafter, the reversing roller pair 28, 29 sandwiches the recording paper and passes and conveys the recording paper in the reversing path r, so that the rear end side at the time of image formation on one side is reversed to the front side. The recording paper having the reversed image is fed again to the conveyance path f and delivered to the registration roller pair 25. As a result, the recording sheet is fed again to the image recording formation position P1 by the image recording apparatus 30 with the other side (one side on which no image recording is formed) as the image recording formation surface, and image formation is performed on both sides. Then, the paper is discharged onto the paper discharge table 22.

  On the other hand, the image recording apparatus 30 includes an exposure unit 31, a photosensitive cartridge 32, a developing rotary unit 33, an intermediate transfer belt 34, a transfer roller 35, and a fixing roller pair 36. The image recording apparatus 30 records received image data such as characters on one or both sides of a recording sheet conveyed by the sheet conveying apparatus 20 and fed to the image recording formation position P1 by an electrophotographic method. Form.

  Briefly, the exposure unit 31 selects laser light on the surface of the photosensitive drum (carrier) 32a in the photosensitive cartridge 32 based on the image data received by the laser beam scanning device (polygon mirror) 31a provided therein. By irradiating and exposing and scanning, an electrostatic latent image based on the image data is formed (image formation) on the surface of the photosensitive drum 32a. The developing rotary unit 33 inserts a developing cartridge 37 for each color for developing the electrostatic latent image on the photosensitive drum 32a with yellow (Y), cyan (C), magenta (M), and black (K) toners. The developing cartridge (developing device) 37 corresponding to the image data forming the electrostatic latent image is positioned at the developing position P2 facing the photosensitive drum 32a, and the toner to be stored is stored in a removable (detachable) manner. The electrostatic latent image is toner-developed by adhering.

  For example, in the case of a monochrome image, the intermediate transfer belt 34 is primarily transferred with a toner image of black (K) toner formed on the photosensitive drum 32a at the transfer position P3 facing the photosensitive drum 32a. And a toner image (toner image) to be transferred onto the recording paper is held on the belt surface. In addition, in the case of a color image, the intermediate transfer belt 34 sequentially forms toner images with yellow (Y), cyan (C), and magenta (M) toner formed on the photosensitive drum 32a (the order is the same). A color toner image that is received at the transfer position P3 so as to be superimposed on the belt surface and transferred onto the recording paper is formed and held. The transfer roller 35 presses (nips) the recording paper fed between the intermediate transfer belt 34 (image recording position P1) and sandwiches and conveys the toner image, thereby recording the toner image. Secondary transfer on paper. The toner transfers from the developing cartridge 37 to the recording paper via the photosensitive drum 32a and the intermediate transfer belt 34 in accordance with the bias voltage between the members.

  The fixing roller pair 36 heat-presses the recording paper conveyed from the image recording formation position P1, thereby fixing the toner image developed and transferred at the development position P2 and the transfer position P3, and also fixing the recording paper. Further, it is nipped and conveyed downstream. As a result, a monochrome image or a color image based on the received image data is recorded and fixed (fixed) on one side or both sides of the recording paper. By repeating such operations, images are continuously recorded on a plurality of sheets. Can be formed.

  Note that the toner remaining on the photosensitive drum 32a after being transferred to the intermediate transfer belt 34 is discharged and collected by a cleaning device (not shown), and thereafter the toner is received from the developing cartridge 37 of the developing rotary unit 33 by a charger. Charged to the potential to be attached. Similarly, the intermediate transfer belt 34 is discharged and charged, and toner transfer (attachment) and recovery are repeated. Further, the toner scattered at the time of collection is collected by a filter 39 a attached to the exhaust duct 39 when the suction fan 38 sucks the apparatus main body side through the exhaust duct 39.

  The developing rotary unit 33 stores a plurality of developing cartridges 37 for developing toner on the electrostatic latent image on the surface of the photosensitive drum 32a in a storing position partitioned by a partition frame 33b that rotates about a rotating shaft 33a. It is configured by mounting). The developing rotary unit 33 is rotated around a rotation shaft 33 a based on a print command including image data from the personal computer PC received by the CPU (control unit) 13 of the engine control unit 12 via the controller unit 11. As a result, the developing cartridge 37 at the developing position P2 facing the photosensitive drum 32a is switched to develop the toner image to be transferred onto one or both sides of the recording paper to form an image.

  For example, the image forming apparatus stores a developing cartridge 37 that stores toner of each color of yellow (Y), cyan (C), magenta (M), and black (K) in the developing rotary unit 33 and the developing rotary unit. By switching the developing cartridge 37 that develops the electrostatic latent image on the photosensitive drum 32a by rotating the unit 33 so as to superimpose or select each color-accommodating toner, it is possible to form a color image to a single color image. It can be used as a simple device.

  In addition, this image forming apparatus is configured to be able to form an image even if the same color toner is stored in all the developing cartridges 37 and stored in the developing rotary unit 33. For example, the same color black (K) toner is used. Four developing cartridges 37 can be mounted. In this case, the developing rotary unit 33 is rotated and the developing cartridge 37 for developing the electrostatic latent image on the photosensitive drum 32a is sequentially switched to be used as a dedicated machine for continuously printing and forming monochrome images. For example, a comfortable image forming operation can be executed by appropriately switching the developing cartridge 37 according to the received image data.

  As shown in FIG. 3, the developing cartridge 37 includes a container 41, a developing roller 42, and a supply roller 43. The container 41 is formed in a similar shape so as to be stored in each storage space (position) partitioned by the partition frame 33b of the developing rotary unit 33, and stores the toner T therein. The developing roller 42 is rotatably supported on the outer peripheral side of the container 41 separated from the rotating shaft 33a of the developing rotary unit 33, and causes the toner T delivered from the supply roller 43 to adhere to the photosensitive drum 32a facing it. . The supply roller 43 is rotatably supported by the container 41 so as to be adjacent to the developing roller 42 on the rotating shaft 33a side of the developing rotary unit 33, and presses and rotates the developing roller 42 to remove the surrounding toner T. Supply. In the container 41 of the developing cartridge 37, a partition plate 41a is installed at a position adjacent to the supply roller 43. The partition plate 41a communicates the space on the rotating shaft 33a side with the upper portion of the installation space of the supply roller 43. Thus, the storage space for the toner T in the container 41 is partitioned. That is, the supply roller 43 constitutes a general supply unit that supplies the toner T to the outer peripheral surface 42 a of the developing roller 42. Needless to say, the supply means is not limited to such a roller type, and may supply toner T by other methods.

  With this configuration, the developing cartridge 37 supplies the toner T in the space on the outer peripheral side of the container 41 partitioned by the partition plate 41a to the developing roller 42 in which the supply roller 43 is pressed and rotated. In addition, when the developing rotary unit 33 rotates by 90 degrees counterclockwise in FIG. 1 and rotates 180 degrees, the developing cartridge 37 stores the toner T stored on the rotating shaft 33a side and the supply roller 43 side of the container 41. After being put together at the upper part of the partition plate 41a (downward in FIG. 1), the toner T contained in the container 41 is stirred and refreshed by further rotating by 90 degrees, and the toner T is transferred to the developing roller 42. Collect on the supply roller 43 side so that supply is possible. That is, in the developing cartridge 37 attached to the developing rotary unit 33 rotating in this way, the stored toner T is replenished while being agitated toward the supply roller 43 by the rotation, and therefore, the adjustment for stirring and replenishing the accommodated toner T is performed. An adjusting device (so-called agitator device or auger device) for performing the operation can be omitted as appropriate. However, if the adjusting cartridge is omitted, the developing cartridge 37 has, for example, a count value by the toner counter, the number of dots of the image, at least before the toner T supplied to the developing roller 42 runs out of the periphery of the supplying roller 43. When the developing operation (image formation) time to be accumulated, the number of developed images to be accumulated, or the usage amount of toner T detected by the measured remaining amount of toner T exceeds a preset value, the developing rotary unit 33 is turned on. The toner T needs to be replenished and agitated.

  Further, the developing cartridge 37 exposes the developing roller 42 from the inside of the container 41 so as to face the photosensitive drum 32a at the developing position P2. The developing cartridge 42 has an outer peripheral surface 42a and an opening of the container 41. The gap defined between them is urged by a sealing member 45 made of a resin material that is urged by an urging member 44 such as a rubber material and press-contacts the outer peripheral surface 42a, and an urging member 46 such as a leaf spring. A regulating blade (regulating member) 47 made of a rubber material (rubber) or the like that is pressed against the outer peripheral surface 42a is disposed.

  The seal member 45 prevents the toner T from leaking out of the container 41 and collects the toner T on the outer peripheral surface 42a of the developing roller 42 that has passed through the developing position without scraping it. The regulating blade 47 is formed in a strip shape extending in the axial direction of the developing roller 42, and when illustrated in an easy-to-understand manner, as shown in FIG. 4, the flat portion 47b on the rear end side with respect to the edge 47a on the front end side as shown in FIG. Is adjusted so as to come into pressure contact with the surface of the outer peripheral surface 42a of the developing roller 42, and the thickness of the toner T rotating while adhering to the outer peripheral surface 42a is scraped off at the leading edge 47a. Regulate the length to be constant.

  The regulating blade 47 adjusts the position where the flat surface portion 47b is pressed against the outer peripheral surface 42a of the developing roller 42 in the tangential direction (left and right direction in FIG. 4), thereby removing the toner T adhering to the outer peripheral surface 42a from the leading edge. The thickness scraped off by 47a can be adjusted. For example, when the pressure contact position with the outer peripheral surface 42a of the developing roller 42 is set near the middle of the flat portion 47b, the thickness of the toner T indicated by the one-dot chain line in FIG. As indicated by the dotted line, when the pressure contact position is adjusted to the front of the flat portion 47b (left side in FIG. 4), the gap that the tip side edge 47a defines between the outer peripheral surface 42a is widened, The toner T entering the toner can be thickened. The toner T on the outer peripheral surface 42a of the developing roller 42 is charged by applying a preset charging voltage to the regulating blade 47, and the supply roller 43 is pressed against the developing roller 42. Some frictional charging is also caused.

  Here, both ends of the developing roller 42 are rotatably supported, and as shown in FIG. 5A, the supply roller 43 is pressed from the back side of the photosensitive drum 32a, and the regulating blade 47 Since they are also pressed from substantially the same direction, the central portion is bent and curved so as to escape from the supply roller 43 and the regulating blade 47 as shown in FIG. For example, as shown in FIG. 6, in the case of the developing roller 42 set to a length corresponding to A4 or A3 size recording paper (about 250 mm to 350 mm), the outer peripheral surface S in a straight state is used. The central portion is curved so as to form a gap G1 of about several μm to several tens of μm, and as a result, the central portion escapes in a direction away from the pressure contact surface of the regulating blade 47. For this reason, when the leading edge of the regulating blade 47 is straight, the toner T adhering to the outer peripheral surface 42a of the developing roller 42 is scraped off more thickly toward the center than at both ends, and the thickness thereof is reduced. It cannot be made uniform.

  For this reason, the regulating blade 47 is manufactured such that the projecting amounts projecting in the tangential direction of the outer peripheral surface 42a of the developing roller 42 are different between the both end portions and the central portion side of the leading edge 47a. Specifically, in the case of the regulating blade 47 having a length corresponding to A4 or A3 size recording paper, as shown in FIG. 7, the center portion of the leading edge 47a with respect to the straight line L in a straight state. Is formed in a curved shape that recedes backward so as to form a gap G2 of about several μm to several hundred μm in the tangential direction of the outer peripheral surface 42a of the developing roller 42 from both ends.

  As a result, the regulating blade 47 is configured so that the tip side edge 47a protrudes forward in the tangential direction from the position facing the outer peripheral surface 42a of the developing roller 42, with the center side relatively to the both end sides. The thickness of the toner T on the central portion side that can be made smaller (retracted) and scraped off by the leading edge 47a to enter between the flat portion 47b can be made relatively small with respect to both end portions. it can. In other words, the regulating blade 47 can make the gap defined between the leading edge 47a and the outer peripheral surface 42a of the developing roller 42 uniform in the axial direction, and evenly distribute the toner T on the outer peripheral surface 42a. Can be set to scrape off. Therefore, the toner T on the outer peripheral surface 42a, which has been thick on the central portion side because the developing roller 42 is curved, is scraped off so as to have a uniform thickness on both end portions, and has a uniform thickness in the axial direction. Can be.

  Specifically, the regulation blade 47 may be formed in a desired curved shape so that the center portion of the front end side edge 47a recedes from the both end sides according to the amount of bending of the developing roller 42. A plate spring (biasing member) 46 such as phosphor bronze or stainless steel having a thickness of about 0.5 to 0.2 mm is set in a mold having a curved molding surface, and a rubber material is injected. The spring 46 is formed by integral molding on the tip side. The regulating blade 47 can also be produced by sticking a rubber material cut into a strip shape to a jig having a desired curved shape and sticking it to the distal end side of the leaf spring 46. When the leaf spring itself is used as the regulating blade, it may be punched with a press die so as to have a desired curved front end side edge.

  Further, as shown in FIGS. 8A and 8B, the leaf spring 46 is fixed to the container 41 of the developing cartridge 37 on the opposite side (rear end side) of the regulating blade 47 (front end side). A frame 48 is fixed. The frame 48 is formed to have the same width as the leaf spring 46, and as shown in FIG. 8C, the center side in the length direction of the fixed surface 48a is curved in a concave shape. The plate spring 46 is fixed to the fixed surface 48a by spot welding at a plurality of locations.

  As a result, when the regulating blade 47 is in pressure contact with the outer peripheral surface 42a of the developing roller 42, the curved shape (fixed surface 48a) of the rear end side central portion of the leaf spring 46 has a central portion of the front end edge 47a. It acts so that it may protrude to the outer peripheral surface 42a side. Therefore, the central portion of the regulating blade 47 tends to approach toward the central portion of the developing roller 42 that curves in the direction of escaping due to the pressure contact of the supply roller 43 or the like, in other words, the shaft of the outer peripheral surface 42 a of the developing roller 42. The front edge 47a is brought close to the outer peripheral surface 42a of the developing roller 42, and the adhering toner T is scraped to a more uniform thickness. be able to. At this time, the leaf spring 46 is pressed in a direction in which the regulating blade 47 is pressed against the developing roller 42 so that a force to be removed from the frame 48 is applied to widen the space between spot welds, in other words, wrinkles between the spot welds. The regulation blade 47 can be uniformly pressed in the axial direction of the outer peripheral surface 42a of the developing roller 42, and the outer edge of the developing roller 42 can be brought into contact with the leading edge 47a of the regulating blade 47. The toner T on the surface 42a can be scraped off evenly.

  As shown in FIGS. 9A and 9B, the leaf spring 46 may have a frame 49 fixed on the rear side on the rear end side with respect to the regulating blade 47. The frame 49 is formed to have a width similar to that of the leaf spring 46, and as shown in FIG. 9C, the center side in the length direction of the fixed surface 49a of the leaf spring 46 is curved in a convex shape. The leaf spring 46 is fixed to the fixed surface 49a by spot welding at a plurality of locations. In this case, spot welding is performed while pressing the leaf spring 46 against the fixed surface 49a of the frame 49. When the frame 49 bent by the pressing is released from the pressing force after the welding is completed, the spot welding is performed. In the direction to widen the gap, in other words, in the direction to eliminate wrinkles and slack between the spot welds, the regulating blade 47 is axially disposed on the outer peripheral surface 42a of the developing roller 42 as in the case of the frame 48. The toner T on the outer peripheral surface 42a can be evenly scraped off by pressing uniformly.

  Further, the intermediate transfer belt 34 of the image forming apparatus is formed in an endless belt shape wound around a primary transfer pulley 51, a secondary transfer pulley 52, a driven pulley 53, and tension pulleys 54 and 55. Yes. The primary transfer pulley 51 is disposed at a transfer position P3 where the developed toner image on the photosensitive drum 32a is primarily transferred to the intermediate transfer belt 34. The primary transfer pulley 51 is placed on the photosensitive drum 32a on the back side of the intermediate transfer belt 34. Face to face. The secondary transfer pulley 52 is disposed at a recording formation position P1 where the toner image on the intermediate transfer belt 34 that has been primarily transferred is secondarily transferred to a recording sheet between the transfer roller 35 and an image is recorded. It faces the transfer roller 35 on the back side of the intermediate transfer belt 34. The driven pulley 53 is disposed on the opposite side of the secondary transfer pulley 52 and is rotated by the rotation of the intermediate transfer belt 34. The tension pulleys 54 and 55 are disposed on both sides of the intermediate transfer belt 34 between the secondary transfer pulley 52 and the driven pulley 53, and tension is applied from the back side thereof so that the intermediate transfer belt 34 does not cause a positional shift or the like. Is multiplied.

  The intermediate transfer belt 34 is provided with, for example, a not-shown protruding piece (so-called shim) that protrudes outward in the planar direction on one side, and the sensor 56 detects this protruding piece every rotation. As a result, the CPU 13 of the engine control unit 12 controls the rotation drive so as to synchronize with the rotation of the photosensitive drum 32a and the conveyance of the recording paper. Thus, the intermediate transfer belt 34 faces the recording sheet conveyed to the image recording formation position P1 facing the transfer roller 35 and repeatedly circulates along the path between the transfer positions P3 facing the photosensitive drum 32a. Thus, the toner images of the respective color toners formed on the photosensitive drum 32a are received at the transfer position P3 and transferred to the recording paper at the image recording formation position P1.

  In this manner, the intermediate transfer belt 34 circulates and rotates, whereas the developing rotary unit 33 needs to sequentially switch the developing cartridge 37 that develops the toner image, particularly when forming a color image. For this reason, the intermediate transfer belt 34 is set longer than the size of the recording paper on which the color image is formed, and holds the toner image to be transferred to the recording paper, whereas the developing rotary unit 33 It is necessary to complete the switching operation of the developing cartridge 37 while the toner image on the intermediate transfer belt 34 rotates between the trailing edge and the leading edge (between the trailing edge and the leading edge of the recording paper, so-called paper). There is.

  The developing cartridge 37 includes a nonvolatile memory 66 and a developing connector 67, and a control connector 68 is disposed on the developing rotary unit 33 main body. The nonvolatile memory 66 can rewrite various information such as the color of toner to be stored, the date of manufacture, and the amount of consumption, in addition to the identification number such as the manufacturing number, in addition to the number of mounting and recycling of the developing cartridge 37 itself. The development side connector 67 is connected to the non-volatile memory 66 and reads and rewrites the stored information. The control-side connector 68 is arranged in the developing rotary unit 33 so that the developing roller 42 faces the developing-side connector 67 of the developing cartridge 37 rotated 90 degrees counterclockwise from the developing position P2 facing the photosensitive drum 32a. It is installed so as not to move to the wall surface, and various types of information are exchanged by contactless communication facing the development side connector 67 of the development cartridge 37 after the development operation. Thereby, the engine control unit 12 of the control unit 10 appropriately grasps various information such as the color information of the toner of the developing cartridge 37 together with the presence or absence and position of the developing cartridge 37 stored in the storing position of the developing rotary unit 33. Then, image forming control including optimal switching control of the developing cartridge 37 is executed.

  The CPU 13 of the engine control unit 12 executes various control operations according to the control program in the ROM 14 after the power is turned on. When the power is turned on or when the developing cartridge 37 is replaced, the non-contact via the connectors 67 and 68 is performed. By performing communication, the presence / absence of the developing cartridge 37 at the storage position of the developing rotary unit 33, the number of times of mounting and the number of recycling, and the like are held (stored) in the main body memory 15. Further, the CPU 13 sequentially reads out various information written in the nonvolatile memory 66 of each developing cartridge 37 via the connectors 67 and 68, and position information, toner color information and consumption for each developing cartridge 37. The amount (remaining amount) is stored in the main body memory 15. Further, the CPU 13 writes various information such as the amount of toner consumed by the image formation into the nonvolatile memory 66 of each developing cartridge 37 via the connectors 67 and 68 during the image forming operation or after the image formation is completed. rewrite.

  Further, the CPU 13 of the engine control unit 12 emits light toward the transfer surface (toner image) on the intermediate transfer belt 34 and photoelectrically converts the reflected light from the toner image on the transfer surface, thereby developing. A so-called patch sensor 69, which includes a reflection type photosensor for detecting the density (the coverage with toner) of the toner image (toner image on the intermediate transfer belt 34) formed on the photosensitive drum 32 a by the cartridge 37, is connected. Has been. The patch sensor 69 is disposed on the downstream side in the rotation direction in the vicinity of the transfer position P3 for transferring the toner image from the photosensitive drum 32a to the intermediate transfer belt 34. As will be described later, the patch sensor 69 is static on the photosensitive drum 32a. The toner on the outer peripheral surface 42a of the developing roller 42 for developing the electrostatic latent image is set to have the smallest thickness, and is arranged at one position near the center in the width direction (near the center of the photosensitive drum 32a). It is installed.

  On the other hand, as described above, the regulating blade 47 is arranged such that the central portion of the leading edge 47a is closer to the end than the both ends so that the toner on the outer peripheral surface 42a of the developing roller 42 is scraped to a uniform thickness. Although it is retracted in the tangential direction of the outer peripheral surface 42a, the protrusion amount of the leading edge 47a is set in view of the arrangement of the patch sensor 69 for detecting the density of the toner image near the center of the photosensitive drum 32a. Specifically, the leading edge 47a of the regulating blade 47 is located on both end sides so that the thickness of the toner on both ends on the outer peripheral surface 42a of the developing roller 42 is the same as or thicker than the central portion. Further, the central portion is retracted in the tangential direction of the outer peripheral surface 42 a of the developing roller 42.

  Then, the CPU 13 transfers the toner on the outer peripheral surface 42a of the developing roller 42 onto the photosensitive drum 32a when the power is turned on or the developing cartridge 37 is replaced (an electrostatic latent image on the photosensitive drum 32a is transferred). (Toner development) Patch processing for adjusting the bias voltage is performed, and the development density of the electrostatic latent image on the photosensitive drum 32a is described in detail, specifically, a high-quality toner image from a solid image to a fine line image. Adjust to be able to form.

  Specifically, the CPU 13 creates an electrostatic latent image that forms a test patch image, for example, a patch image such as a solid image or a fine line image, in a small area in the center in the axial direction on the photosensitive drum 32a. Then, after developing the toner by the developing cartridge 37, the density of the patch image (toner image) transferred onto the intermediate transfer belt 34 is detected by the patch sensor 69, and the photosensitive drum 32a and the developing roller are detected based on the detection result. The bias voltage between 42 is adjusted. At this time, the CPU 13 changes the bias voltage for toner development of the patch image to, for example, voltages V1 to V4 as shown in FIG. A bias voltage V5 that can be set to a density (adhesion amount) is calculated by an interpolation method (complementation method) based on the detection result, and the bias voltage for developing the electrostatic latent image on the photosensitive drum 32a is optimized. Turn into. The bias voltage V5 obtained by the patch processing may be written in the nonvolatile memory 66 for each developing cartridge 37 and used at the time of replacement.

  As a result, the toner on the outer peripheral surface 42a of the developing roller 42 has a total length in the axial direction as a whole, with the leading edge 47a of the regulating blade 47 at least not having both ends in the axial direction thinner than near the center. The patch sensor 69 detects the toner density of the patch image developed with the toner near the center and adjusts the bias voltage for transferring the toner from the developing roller 42 to the photosensitive drum 32a. Is done. Therefore, the density of the toner image can be adjusted based on the developed patch image so that it is not thicker than at least other portions, and the toner image is erroneously adjusted to partially thin the toner image. Can be avoided. Therefore, in addition to making the toner thickness on the outer peripheral surface 42a of the developing roller 42 uniform in the axial direction with high quality, the development density of the electrostatic latent image on the photosensitive drum 32a is optimized to achieve high quality. Images can be formed.

  Thus, in the present embodiment, the amount of protrusion of the leading edge 47a of the regulating blade 47 protruding in the tangential direction of the outer peripheral surface 42a of the developing roller 42 is relatively small by retreating the central portion with respect to both ends. The toner on the outer peripheral surface 42a of the developing roller 42, which has a simple structure that curves in the direction of escape, is scraped off at the leading edge 47a of the regulating blade 47, and the thickness of the toner that enters between them is determined. It can be made uniform in the axial direction. Further, by curving the central portion of the regulating blade 47 in a direction in which it is pressed against the developing roller 42, the gap between the outer peripheral surface 42a and the leading edge 74a can be made uniform in the axial direction. The axial thickness of the toner on the outer peripheral surface 42a can be made uniform with higher accuracy in combination with the effect of retreating the central portion of the leading edge 47a of the regulating blade 47. Therefore, the electrostatic latent image on the surface of the photosensitive drum 32a can be developed with the toner with high quality, and a high quality image can be formed.

  As another aspect of the present embodiment, in the above-described embodiment, the protrusion amount of the leading edge 47a of the regulating blade 47 is adjusted so that the toner thickness on the outer peripheral surface 42a of the developing roller 42 is uniform in the axial direction. However, since the gap between the photosensitive drum 32a and the photosensitive drum 32a is also uneven due to the bending of the developing roller 42, the non-uniform gap is transferred from the outer peripheral surface 42a of the developing roller 42 to the photosensitive drum 32a. When there is a problem in the development quality of the electrostatic latent image on the photosensitive drum 32a due to the so-called conveyance amount (flying amount), the regulating blade 47 is set so that the conveyance amount is uniform in the axial direction. The amount of protrusion of the leading edge 47a can be adjusted.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea. For example, in the embodiment described above, an apparatus capable of storing a plurality of developing cartridges in the developing rotary unit will be described as an example. However, the present invention is not limited to this, and an image forming apparatus of a type in which one developing cartridge is attached or detached is also suitable. Can be applied to. Further, the case where the toner image on the photosensitive drum is transferred to the recording paper via the intermediate transfer belt will be described as an example. However, the present invention is not limited to this, and an image forming apparatus of a type that directly transfers from the photosensitive member to the recording paper may be used. Needless to say, it can be suitably applied.

1 is a perspective front view showing a schematic overall configuration of an image forming apparatus according to an embodiment of the present invention. It is a related block diagram explaining the control part. It is a longitudinal cross-sectional view which shows the principal part structure. It is the side view which looked at the relationship between the developing roller and a control member from the axial direction. It is a figure which shows the relationship between the carrier, a developing roller, and a supply roller, (a) is the side view seen from the axial direction, and the top view seen from the normal line direction. It is a top view explaining the curve of the developing roller. It is a top view explaining the shape of the regulating member. It is a figure explaining attachment of the regulation member, (a) is a side view seen from the side, (b) is a top view seen from the upper part, (c) is an elevation view seen from the back is there. It is a figure which shows the other example of the control member, (a) is the side view seen from the side, (b) is the top view seen from the upper direction, (c) is the elevation view seen from the back It is. It is a graph explaining adjustment of the bias voltage based on the detection by the patch sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Control unit 11 Controller part 12 Engine control part 15 Main body memory 20 Paper conveyance apparatus 21 Paper cassette 22 Paper discharge table 25 Registration roller pair 30 Image recording apparatus 31 Exposure unit 32a Photosensitive drum 33 Development rotary unit 34 Intermediate transfer belt 35 Transfer roller 36 fixing roller pair 37 developing cartridge 41 container 42 developing roller 43 supply roller 45 sealing member 46 leaf spring 47 regulating blade 47a tip side edge 47b plane part 48, 49 frame 66 nonvolatile memory 67 developing side connector 68 control side connector 69 patch sensor P1 Recording position P2 Development position P3 Transfer position

Claims (2)

A carrier carrying an electrostatic latent image;
A developing roller for developing the electrostatic latent image with toner;
Supply means for pressing the developing roller and supplying the toner to the developing roller;
A regulating member that is pressed against the developing roller in substantially the same direction as the direction in which the supply means is pressed against the developing roller,
When the opposite side in the rotation direction of the developing roller is defined as the leading end side, and both axial ends of the developing roller are defined as both end portions ,
The restricting member includes a plate member and an elastic member provided on a front end side of the plate member,
The elastic member has a flat surface portion on the rear end side than the front end side edge of the elastic member in pressure contact with the developing roller, and a central portion recedes toward the rear end side from both end portions of the front end side edge. Is formed into a curved shape,
The plate member has a rear end side of the plate member fixed to a fixed portion of the fixed member,
The fixed portion is curved in a direction in which a central portion is closer to the developing roller than both end portions of the fixed portion,
As the fixed contact portion is curved, the plate member is also curved, and due to the curvature of the plate member, the central portion of the elastic member is curved in a direction closer to the developing roller than both end portions of the elastic member. An image forming apparatus.   The image forming apparatus according to claim 1, further comprising a patch sensor that detects a developed patch image density at an axially central portion of the carrier.

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