JP2013238699A - Development device and image processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a development device while keeping agitating performance of a developer even when the number of agitation members are set as two, which is the necessary minimum number.SOLUTION: In a developing tank 71, a development roller 70 that carries a developer to rotate, a supply roller 72 for supplying the development roller 70 with the developer while rotating, two agitation members 74,75 for agitating the developer in the developing tank 71 are provided. In an agitation area R surrounded by a plane P1 passing through the rotation axis of the development roller 70 and a plane P2 parallel to the plane P1 and passing through the rotation axis of the supply roller 72, the two agitation members 74,75 are disposed. The rotation direction of the supply roller 72 and the rotation direction of the agitation members 74,75 are the same.

Description

  The present invention relates to a developing device that develops an electrostatic latent image formed on an electrostatic latent image carrier with a developer, and an image processing apparatus including the developing device.

  In an electrophotographic image processing apparatus, the surface of an electrostatic latent image carrier such as a photoconductor is charged, and an electrostatic latent image is formed by exposing the charged area according to image information. Is developed and visualized (developed).

  In this electrophotographic system, a one-component developing system using only toner without using a carrier is adopted. The developer made of non-magnetic toner stirred by the stirring member is supplied to the developing roller made of urethane rubber, and the developer carried on the developing roller is transported to the photoconductor and used for development.

  Compared with the two-component development method, the one-component development method requires fewer members constituting the development device, and the development device can be downsized. However, since there are few members that stir the developer, the developer in the developing tank hardly flows and easily stays. Then, there is a problem that developer packing occurs, the developer is not supplied to the supply roller and the development roller, and image defects such as blurring occur.

  In the developing device of Patent Document 1, a plurality of stirring members are provided in the developing tank. That is, the stirring blade, the two toner conveying spirals, and the stirring shaft are rotatably installed above the supply roller. Thereby, the toner supply force to the supply roller is improved, the occurrence of toner aggregation near the supply roller is prevented, and the deterioration of the print quality can be suppressed.

JP 2012-27110 A

  In the above developing device, since four stirring members are installed in the developing tank, there is a limit to downsizing the developing device. Therefore, in view of the above, an object of the present invention is to provide a developing device and an image processing apparatus including the developing device that can maintain the stirring ability of the developer even when the minimum number of stirring members is two.

  The developing device of the present invention includes a developing roller that carries and rotates the developer in the developing tank, a supply roller that supplies the developer to the developing roller while rotating, and two developers that stir the developer in the developing tank. And a stirring member. Two stirring members are arranged in a stirring region defined by the outer periphery of the developing roller and the outer periphery of the supply roller. The image processing apparatus includes this developing device.

  The two stirring members are arranged without protruding from the outer periphery of the developing roller or the outer periphery of the supply roller. Therefore, the minimum necessary stirring member is positioned above the supply roller, so that the sufficiently stirred developer can be conveyed to the supply roller, and the developing device can be miniaturized.

  Here, the stirring area is an area surrounded by a plane passing through the rotation axis of the developing roller and a plane parallel to the plane and passing through the rotation axis of the supply roller. And the rotating shaft of two rotating stirring members is located in a stirring area. As a result, the two stirring members are located on the semicircular side near the developing roller of the supply roller. The developer stirred by the stirring member can be merged with the developer conveyed by the supply roller toward the developing roller.

  A regulating member that regulates the layer thickness of the developer carried on the developing roller is provided, and the shortest distance between each stirring member and the supply roller or the regulating member is made smaller than the radius of the developing roller and the radius of the supplying roller. That is, the shortest distance S is 1 mm ≦ S ≦ 5 mm.

  Since the agitating member is disposed in the vicinity of the regulating member, the developer that has been regulated and returned by the regulating member can be agitated, and the retention of the developer can be prevented.

  The rotation direction of the supply roller and the rotation direction of the stirring member are the same direction. The developer conveyance direction is reversed between the supply roller and the stirring member. Accordingly, the developer is stirred and mixed between the supply roller and the stirring member, and the supply roller can supply the sufficiently stirred developer to the developing roller.

  According to the present invention, the development apparatus can be reduced in size while maintaining the agitation of the developer by the minimum two agitation members.

The figure which shows schematic structure of the image processing apparatus of this invention Schematic sectional view of the developing device The figure which shows the stirring area in a developing device The figure which shows the shortest distance of a stirring member, a supply roller, and a control member

  An image processing apparatus of this embodiment is shown in FIG. In FIG. 1, main components of the image processing apparatus 100 are illustrated in a simplified manner. The image processing apparatus 100 includes a plurality of photoreceptors 51 that are electrostatic latent image carriers. The image processing apparatus 100 is a tandem color image processing apparatus that includes four photoconductors 51 for a yellow image, a magenta image, a cyan image, and a black image, and is capable of forming a color image. The image processing apparatus 100 is based on image data transmitted from various terminal devices such as personal computers connected via a network and image data read by a document reading device such as a scanner. And a printer function for forming a color image or a monochrome image on the paper P.

  As shown in FIG. 1, the image processing apparatus 100 includes an image forming station unit 50 that forms a toner image on a sheet P, a fixing device 40 that fixes a toner image formed on the sheet P by the image forming station unit 50, and a sheet A transport unit 30 that transports the paper P from the supply tray 60 on which the P is placed to the fixing device 40 through the image forming station unit 50 is provided.

  The image forming station unit 50 includes four image forming station units 50Y, 50M, 50C, and 50B for yellow image, magenta image, cyan image, and black image, respectively.

  Between the supply tray 60 and the fixing device 40, a yellow image forming station unit 50Y, a magenta image forming station unit 50M, a cyan image forming station unit 50C, and a black image forming station unit 50B are provided from the supply tray 60 side. Arranged in this order.

  The image forming station portions 50Y, 50M, 50C, and 50B for the respective colors have substantially the same configuration except for the type of toner. Based on the image data corresponding to each color, toner images of yellow, magenta, cyan, and black are formed, respectively, and finally the toner images of the respective colors are transferred onto the paper P.

  The image forming station unit 50 is configured to form four color images of yellow, magenta, cyan, and black. However, the image forming station unit 50 is not limited to these four colors. For example, the density is lower in the same hue as cyan and magenta. A configuration in which toner images of six colors including light cyan (LC) and light magenta (Lm) are added may be used.

  In FIG. 1, the reference numerals of the component parts of the image forming station sections are described with the image forming station section 50Y for yellow image as a representative, and the reference numerals of the component parts of the other image forming station sections 50M, 50C, 50B. Is omitted.

  Each of the image forming station units 50Y, 50M, 50C, and 50B includes a photoreceptor 51 that is an electrostatic latent image carrier on which an electrostatic latent image is formed, and is charged around the photoreceptor 51 along the circumferential direction. A device 52, an exposure device 53, a developing device 54, a transfer roller 55, and a cleaning device 56 are sequentially arranged.

  The photoreceptor 51 has a substantially cylindrical drum shape having a photosensitive material such as OPC (Organic Photoconductor) on the surface. The photoconductor 51 is disposed below the exposure device 53 and is controlled to be rotationally driven in a predetermined direction (the direction of arrow F in the figure) by a drive device and a control device.

  The charging device 52 uniformly charges the surface of the photoconductor 51 to a predetermined potential. The charging device 52 is disposed above the photoreceptor 51 and in proximity to the outer peripheral surface thereof. In the present embodiment, a contact-type charging roller is used. However, the invention is not limited to this, and a charging device such as a charger type, a brush method, or an ion emission charging method may be used.

  The exposure device 53 irradiates the surface of the photoconductor 51 charged by the charging device 52 with a laser beam based on the image data output from the image processing unit in the control device, thereby exposing the photoconductor 51. An electrostatic latent image corresponding to the image data is written on the surface. When image data corresponding to yellow, magenta, cyan, and black is input, the exposure devices 53 of the image forming station units 50Y, 50M, 50C, and 50B form electrostatic latent images corresponding to the corresponding colors, respectively. To do. As the exposure device 53, a laser scanning unit (LSU) provided with a laser irradiation unit and a reflection mirror, or a writing device (for example, a writing head) in which light emitting elements such as EL and LED are arranged in an array can be used.

  The developing device 54 includes a developing roller 70 that is a developer carrying member that carries the developer. A region where the developing roller 70 and the photosensitive member 51 are close to each other is a developing region in which the developer moves to the photosensitive member 51, and the developing roller 70 is configured to convey and supply the developer to the developing region. . The developing device 1 is a so-called one-component developing type developing device that uses a non-magnetic toner as a developer, and develops an electrostatic latent image formed on the surface of the photoconductor 51 by an exposure device 53 to develop a toner image ( A visible image).

  The developing devices 54 of the image forming station units 50Y, 50M, 50C, and 50B respectively contain yellow, magenta, cyan, and black developers according to the image formation of each color. These developers include toner charged to the same polarity as the surface potential of the charged photoreceptor 51.

  The transfer roller 55 transfers the toner image formed on the photoconductor 51 to the surface of the paper P conveyed by the conveyance belt 33. The transfer roller 55 is applied with a bias voltage having a polarity opposite to the charging polarity of the toner (positive polarity in this embodiment).

  The cleaning device 56 removes and collects the toner remaining on the outer peripheral surface of the photoreceptor 51 after the toner image is transferred onto the paper P. In the present embodiment, the photosensitive member 51 is disposed at a position substantially opposite to the developing device 1 with the photosensitive member 51 interposed therebetween, and on the side of the photosensitive member 51.

  The conveyance unit 30 includes a driving roller 31, a driven roller 32, and a conveyance belt 33, and conveys the paper P on which the toner images of each color are transferred in the image forming station units 50Y, 50M, 50C, and 50B. An endless conveyance belt 33 is stretched between the driving roller 31 and the driven roller 32. The transport unit 30 sequentially transports the paper P fed from the supply tray 60 to the image forming station units 50Y, 50M, 50C, and 50B.

  The fixing device 40 includes a heating roller 41 and a pressure roller 42. When the paper P passes through the fixing nip portion where they abut, the fixing device 40 fixes the toner image transferred onto the paper P by thermocompression bonding to the paper P.

  In the image processing apparatus 100 configured as described above, when the paper P transported by the transport unit 30 passes through the positions facing the photoreceptors 51 of the image forming station units 50Y, 50M, 50C, and 50B, those sheets At the facing position, the toner images on the respective photoconductors 51 are sequentially transferred onto the paper P by the action of the transfer electric field by the transfer roller 55 disposed below via the conveyance belt 33. As a result, the toner images of the respective colors are transferred so as to overlap on the paper P, and a desired full-color toner image is formed on the paper P. The paper P on which the toner image has been transferred is subjected to fixing processing of the toner image by the fixing device 40. Thereafter, the paper P on which the image has been formed is sent to a paper discharge tray.

  Next, the developing device 54 of each image forming station unit 50Y, 50M, 50C, 50B is shown in FIG. The developing device 54 is arranged to face the developing tank 71 and the photosensitive member 51 that is an electrostatic latent image carrier, and is a rotatable developing roller that carries the developer on the surface and conveys the developer to the photosensitive member 51. 70, a rotatable supply roller 72 for supplying the developer to the developing roller 70, a regulating member 73 for regulating the layer thickness of the developer supplied to the photosensitive member 51, and the developer in the developing tank 71 2 Two stirring members 74 and 75 are provided.

  The developing tank 71 is made of, for example, a hard synthetic resin and stores a one-component developer made of toner. As the toner, a toner having a polyester resin as a main component and a volume average particle diameter of 8 μm prepared by a pulverization method is used. A toner supply container is detachably mounted above the developing tank 71. The toner is supplied from the toner supply container into the developing tank 71.

  The developing roller 70 has an elastic body layer such as urethane rubber, carries the developer on the surface, and conveys the developer while rotating. The rotating shaft of the developing roller 70 is rotatably supported by a frame 76 provided in the developing tank 71 and is driven to rotate by a motor. The developing roller 70 is in contact with the photoconductor 51 and is arranged so that the rotation axis is parallel to the rotation axis of the photoconductor 51. The rotation direction of the developing roller 70 is opposite to the rotation direction of the photoconductor 51. The diameter of the developing roller 70 is 12 mm.

  The supply roller 72 is composed of a porous elastic member such as foamed urethane or the like around the rotation shaft, and the developer is rubbed against the developing roller 70 while adsorbing the developer in the pores on the surface, thereby removing the developer from the developing roller 70. To supply. Further, the supply roller 72 cleans excess developer remaining on the developing roller 70 after development. The supply roller 72 is in contact with the developing roller 70, and the rotation shaft of the supply roller 72 is rotatably supported by the frame 76 of the developing tank 71 and is driven to rotate by a motor.

  The amount of biting at the contact portion between the supply roller 72 and the developing roller 70 is 0.9 mm, and the width of the contact portion in the axial direction is set to 215 mm. As the elastic member of the supply roller 72, a urethane sponge having an Asker FP hardness of 52 degrees is used. The diameter of the supply roller 72 is larger than that of the developing roller 70 and is 13.8 mm.

  The restricting member 73 uses an L-shaped thin blade made of metal such as SUS. The regulating member 73 is disposed above the developing roller 70, and the leading end side of the regulating member 73 is bent in an L shape in a direction away from the developing roller 70. The front end side of the regulating member 73 contacts the developing roller 70 through the developer. The other end side of the regulating member 73 is fixed to the developing tank 71.

  The regulating member 73 regulates the amount of developer carried by the developing roller 70 so that the developer layer thickness is constant. A developer having a charged charge is carried on the surface of the developing roller 70 with a constant layer thickness, and is supplied from the developing roller 70 to the photoconductor 51 in accordance with a potential difference between the developing roller 70 and the photoconductor 51, and electrostatic latent The image is developed to form a toner image.

  The first and second stirring members 74 and 75 have a rod-shaped stirring body 81 that rotates around the rotation shaft 80, and one stirring body 81 parallel to the axial direction of the developing roller 70 and the supply roller 72 is an arm. It is set as the structure attached to the rotating shaft 80 via. The two stirring members 74 and 75 have the same structure. A rotating shaft 80 is rotatably supported by the developing tank 71 and is driven to rotate by a motor. The stirring members 81 of the stirring members 74 and 75 rotate in the same direction as the supply roller 72. Here, the peripheral speed of the developing roller 70 is 243 mm / sec, the peripheral speed of the photosensitive member 51 is 180 mm / sec, the peripheral speed of the supply roller 72 is 194 mm / sec, and the rotation speed of each of the stirring members 74 and 75 is 60 rpm.

  As shown in FIG. 3, the stirring members 74 and 75 are arranged above the supply roller 72 and in a stirring region R defined by the outer periphery of the developing roller 70 and the outer periphery of the supply roller 72. The stirring region R is a region surrounded by a first plane P1 passing through the rotation axis of the developing roller 70 and a second plane P2 parallel to the plane P1 and passing through the rotation axis of the supply roller 72. . The first and second planes P1 and P2 are orthogonal to a reference plane P3 passing through the rotation axis of the developing roller 70 and the rotation axis of the supply roller 72. The supply roller 72 is located obliquely below the developing roller 70. Accordingly, the horizontal distance from the outermost outer periphery of the developing roller 70 to the outermost outer periphery of the supply roller 72 can be made smaller than the sum of the diameter of the developing roller 70 and the diameter of the supply roller 72. The direction width can be narrowed.

  The second stirring member 75 is positioned obliquely below the first stirring member 74, and the rotation shaft 80 of each stirring member 74, 75 is positioned in the stirring region R. A plane P4 passing through the rotation shaft 80 of each stirring member 74, 75 is parallel to the reference plane P3. The two stirring members 74 and 75 are located on the semicircular side of the supply roller 72 close to the developing roller 70.

  The shortest distance between each stirring member 74, 75 and the supply roller 72 or the regulating member 73 is smaller than the radius of the developing roller 70 and the radius of the supply roller 72. The shortest distance between the first stirring member 74 and the supply roller 72 is A, the shortest distance between the second stirring member 75 and the supply roller 72 is B, and the shortest distance between the first stirring member 74 and the front end of the regulating member 73. Where C is 1 mm ≦ A, B, C ≦ 5 mm. Further, if the distance between the rotation shaft 80 of the first stirring member 74 and the rotation shaft 80 of the second stirring member 75 is D, D ≦ 6.9 mm. That is, the distance D is equal to or less than the radius of the supply roller 72.

  By the rotation of the first stirring member 74, the developer at the upper part of the developing tank 71 is stirred. The developer that is regulated and pushed back by the regulating member 73 stays in the vicinity of the tip of the regulating member 73. However, since the first stirring member 74 is disposed close to the regulating member 73, the developer in the vicinity of the regulating member 73 is conveyed toward the second stirring member 75. By the rotation of the second stirring member 75, the developer conveyed from the first stirring member 74 and the developer above the supply roller 72 are stirred and mixed.

  Between the second stirring member 75 and the supply roller 72, the developer transport direction by the second stirring member 75 is opposite to the developer transport direction by the supply roller 72. The developer mixed by the second stirring member 75 is pushed away and stirred by the developer conveyed by the supply roller 72. Finally, the developer is conveyed toward the developing roller 70 while being stirred.

  By arranging the two agitating members 74 and 75 in the agitating region R in this way, it is possible to suppress the stagnation of the developer in the vicinity of the developing roller 70 and the regulating member 73 and to develop while sufficiently agitating the developer. It can be conveyed toward the roller 70. Therefore, the minimum required two stirring members 74 and 75 can prevent the developer from being fused, a sufficient stirring effect can be obtained, and the occurrence of image defects can be prevented.

  The two agitating members 74 and 75 are disposed in the agitating region R defined by the outer periphery of the developing roller 70 and the outer periphery of the supply roller 72, and the rotation locus of the agitating body 81 of the agitating members 74 and 75 It is located inside the vertical tangent T of the outer periphery of 72, that is, closer to the rotation axis of the supply roller 72. Further, it is located inside the vertical tangent of the outer periphery of the developing roller 70. Therefore, the horizontal width of the developing tank 71 is defined by the developing roller 70 and the supply roller 72, and the space between the supply roller 72 and the side wall of the developing tank 71 can be narrowed. Can be realized.

  In addition, this invention is not limited to the said embodiment, Of course, many corrections and changes can be added to the said embodiment within the scope of the present invention. The stirring bodies of the two stirring members may be rotated in the same phase. Although the rotation trajectories of the two stirring bodies intersect, each stirring body does not collide. Therefore, the distance between the rotating shafts of the two stirring members can be shortened, leading to a reduction in the size of the developing tank. Further, as the stirring member, a rod or blade attached to the support shaft may reciprocate like a pendulum. Alternatively, the stirring member may be screwed.

51 Photoconductor 54 Developing Device 70 Developing Roller 71 Developing Tank 72 Supply Roller 73 Restricting Member 74 Stirring Member 75 Stirring Member 79 Guide Portion 80 Rotating Shaft 81 Stirring Body R Stirring Area P1 First Plane P2 Second Plane

Claims (7)

The developing tank includes a developing roller that supports and rotates the developer, a supply roller that supplies the developer to the developing roller while rotating, and two stirring members that stir the developer in the developing tank. 2. A developing device comprising two stirring members arranged in a stirring region defined by an outer periphery of a roller and an outer periphery of a supply roller. 2. The developing device according to claim 1, wherein the agitation region is a region surrounded by a plane passing through the rotation axis of the developing roller and a plane parallel to the plane and passing through the rotation axis of the supply roller. . The developing device according to claim 1, wherein the rotating shaft of the rotating stirring member is located in the stirring region. A regulating member for regulating the layer thickness of the developer carried on the developing roller is provided, and the shortest distance between each agitating member and the supply roller or the regulating member is made smaller than the radius of the developing roller and the radius of the supplying roller. 4. The developing device according to claim 1, wherein The developing device according to claim 4, wherein the shortest distance S is 1 mm ≦ S ≦ 5 mm. 6. The developing device according to claim 1, wherein the rotation direction of the supply roller is the same as the rotation direction of the stirring member. An image processing apparatus comprising the developing device according to claim 1.

Images