JP2012128164A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device that enables recycling of a toner regulating member without requiring special repair or cleaning even in a case where the toner regulating member is used for a long period of time.SOLUTION: A developing device 1 includes a developing roller 7 and a developing blade 2. The developing blade 2 has a plate spring member 2b and an abutting member 2c. It is assumed that the face of a contact member 2c, located on one of the side 2b1 of the plate spring member 2b, is a first face 2c1, and that the face of the contact member 2c, located on the other side 2b2 of the plate spring member 2b, is a second face 2c2. In this case, when the developing blade 2 is fixed to a developing container 3 so that the one side 2b1 and the other side 2b2 of the plate spring member 2b are reversed, the angle at which the developing blade 2 is arranged to the developing roller 7 is set such that a second contact part where the second face 2c2 of the contact member 2c contacts the developing roller 7 does not overlap the surface of the developing roller 7, due to a relation with a first contact part such that the first face 2c1 of the contact member 2c contacts the developing roller 7.

Description

  The present invention relates to a developing device including a toner carrier that carries toner, and a toner regulating member that abuts against the toner carrier and regulates the toner layer thickness on the surface of the toner carrier.

  Conventionally, the invention described in Patent Document 1 is disclosed as an invention that includes a developing roller that is a toner carrier that carries toner and a developing blade that is a regulating member that regulates the toner layer thickness on the surface of the developing roller. ing. In the invention described in Patent Document 1, the base end of the developing blade is fixed to the developing device main body by a holding member, and a contact member that contacts the developing roller is provided at the tip of the developing blade.

  On the other hand, in recent years, with increasing awareness of environmental problems, manufacturers are demanding to collect used process cartridges and developing devices from users and recycle them.

Japanese Patent Laid-Open No. 60-046577

  However, in the invention described in Patent Document 1, for example, the developing blade has the following problem that it is difficult to recycle immediately after being removed.

  First, not a few fixed matters are adhered to the surface of the collected developing blade due to long-term use. The main component of the fixed matter is fine particles used as a fine particle resin or toner external additive contained in the toner. These fine particles are considered to gradually melt and accumulate on the surface of the developing blade with frictional heat and pressure when the developing blade regulates the toner layer thickness. Since these fixed objects cannot be repaired by simple cleaning, they must be given up for recycling as parts.

  Secondly, the collected developing blade is plastically deformed. Since the developing blade always presses the developing roller, the developing blade remains slightly bent after a long period of use. Such plastic deformation leads to a decrease in the pressing force by the developing blade and a change in the contact angle of the developing blade with respect to the developing roller. Therefore, recycling as a part must be abandoned.

  In view of the above circumstances, the present invention provides a developing device capable of recycling a toner regulating member without special repair or cleaning even when the toner regulating member is used for a long period of time. Is an issue.

  In order to solve the above problems, a developing device of the present invention includes a toner carrier that carries toner, and a toner regulation member that regulates the amount of toner carried on the toner carrier, and the toner regulation member Is formed integrally with a leaf spring member whose base end is fixed to the developing device main body and a substantially constant radius of curvature from one surface to the other surface at the tip of the leaf spring member. An abutting member provided at the tip of the leaf spring member, the surface of the abutting member located on the one surface of the leaf spring member being the first surface, and the leaf spring member When the surface of the abutting member located on the other surface of the second member is the second surface, the toner restricting member is placed on the developing member so that the one surface and the other surface of the leaf spring member are reversed. When fixed to the apparatus body, the second surface of the contact member is The second abutting portion that abuts on the toner carrier has a relationship with the first abutting portion on which the first surface of the abutting member abuts on the toner carrier on the surface of the toner carrier. The arrangement angle of the toner regulating member with respect to the toner carrier is set so that the positions do not overlap.

  According to the present invention, even when the toner regulating member is used for a long period of time, the toner regulating member can be recycled without special repair or cleaning.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus including a developing device according to Embodiment 1 of the present invention. It is sectional drawing which shows the structure of a cartridge. It is a disassembled perspective view which shows the structure of a developing blade. FIG. 3 is an enlarged cross-sectional view illustrating a configuration of a developing blade. It is sectional drawing etc. which show the shape of the image development blade concerning a comparative example. It is an expanded sectional view showing the contact state of a developing blade and a developing roller. It is a conceptual diagram which shows the state which the leaf | plate spring member of a developing blade contacts with a different contact angle with respect to a developing roller. FIG. 5 is a conceptual diagram showing a force acting at a moment when a static friction force much larger than a force with which a developing blade presses a developing roller is generated. It is a conceptual diagram which shows the state which the leaf | plate spring member of the image development blade contact | abutted with respect to the virtual straight line PR with the contact angle of 86 degrees. It is a conceptual diagram which shows the state which the leaf | plate spring member of the image development blade contact | abutted with the contact angle of 40 degrees with respect to virtual straight line PR. FIG. 6 is a cross-sectional view illustrating a configuration of a developing blade included in a developing device according to a second embodiment. FIG. 10 is a cross-sectional view illustrating a configuration of a developing blade provided in a developing device according to Embodiment 3.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, since the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions, there is no specific description. As long as the scope of the invention is not limited to these, it is not intended.

  FIG. 1 is a cross-sectional view illustrating a configuration of an image forming apparatus 100 including a developing device 1 according to a first embodiment of the invention. The image forming apparatus 100 is a laser beam printer, for example. As shown in FIG. 1, the image forming apparatus 100 has an image forming apparatus main body (hereinafter, simply referred to as “apparatus main body”) 100A. Inside the apparatus main body 100A, an image forming unit 51 for forming an image is provided. Provided. The image forming unit 51 includes a photosensitive drum 11 that is an “image carrier”, a transfer roller 103 a that is a part of a “transfer device”, and the like.

  As shown in FIG. 1, a process cartridge (hereinafter referred to as “cartridge 8”) including the developing device 1, an exposure device 105, a feeding cassette 101, a transfer roller 103a, and a fixing device 104 are included in the apparatus main body 100A. Provided. In addition, a tray 106 as a discharge unit is provided on the upper portion of the apparatus main body 100A. The cartridge 8 is detachable from the apparatus main body 100A.

  The exposure device 105 scans and exposes the photosensitive drum 11 by reflecting the laser beam 105a to the rotating polygon mirror. Further, the feeding cassette 101 accommodates the recording material S (for example, paper).

  When the image forming apparatus 100 performs a printing operation based on image information transmitted from a personal computer or the like, first, a toner image is formed on the photosensitive drum 11 using the cartridge 8 and the exposure device 105. As the toner image rotates and moves to the transfer unit 103, the recording material S is conveyed from the feeding cassette 101 to the transfer unit 103.

  In the transfer unit 103, the toner image on the surface of the photosensitive drum 11 is transferred to the recording material S. Since the toner t has an electric charge, it can be transferred onto the recording material S by providing a potential difference between the transfer roller 103a and the photosensitive drum 11.

  Next, the toner image transferred onto the recording material S is transported to the fixing device 104, and the toner image is fixed onto the recording material S by being heated and melted by the heating member 104a and the pressure member 104b provided above and below the transport path. To do. Finally, the recording material S is conveyed to the tray 106.

  FIG. 2 is a cross-sectional view showing the configuration of the cartridge 8. As shown in FIG. 2, the cartridge 8 includes a developing device 1, a photosensitive drum 11, a cleaner 9, and a charging roller 10. By combining the cartridge 8 with the exposure device 105 and the transfer roller 103a, a toner image can be formed by charging, exposure, development, transfer, and cleaning. Hereinafter, a method for forming a toner image will be described.

  First, a potential difference is generated between the surface of the rotating charging roller 10 and the photosensitive drum 11, and the surface of the photosensitive drum 11 is uniformly and continuously charged so as to have a desired potential. Next, the surface of the photosensitive drum 11 is irradiated from the exposure device 105 with a laser beam 105a (see FIG. 1), and an electrostatic image (electrostatic latent image) corresponding to the image information is drawn.

  On the surface of the photosensitive drum 11, a developing roller 7, which is a “toner carrier” that carries toner, is disposed. Further, the tip of the developing blade 2 that is a “toner regulating member” that regulates the amount of toner carried on the developing roller 7 faces the surface of the developing roller 7. While the electrostatic image described above moves while rotating to the developing unit facing the developing roller 7, the toner t uniformly coated on the surface of the developing roller 7 with the developing blade 2 becomes an electrostatic image on the surface of the photosensitive drum 11. The electrostatic image is developed by moving.

  At this time, the toner t on the surface of the developing roller 7 is charged. Therefore, the potential of the developing roller 7 is set so as to be between the potential (exposure portion potential) subjected to exposure of the electrostatic image and the potential (charge portion potential) not received, whereby the toner t is applied to the photosensitive drum 11. The movement can be controlled. Here, since the contact developing method is used, the developing roller 7 is in pressure contact with the photosensitive drum 11 via the toner t. The toner image thus formed is rotationally moved to the transfer unit 103 (see FIG. 1).

  In the transfer unit 103 (see FIG. 1), the toner t can be transferred onto the recording material S by providing a potential difference between the transfer roller 103a and the photosensitive drum 11. The toner t remaining on the surface of the photosensitive drum 11 without being completely transferred is scraped off by the cleaning blade 9 a of the cleaner 9, and the surface of the photosensitive drum 11 is rotated to be charged again by the charging roller 10.

  The cleaner 9 has a cleaning blade 9a and a waste toner container 9b. The cleaning blade 9a is made of an elastic member such as urethane rubber or silicon rubber. When the cleaning blade 9a comes into contact with the photosensitive drum 11, the toner t on the surface of the photosensitive drum 11 is scraped off and stored in the waste toner container 9b.

  Next, the toner used in the developing device 1 will be described. The toner t is a negative-polarity non-magnetic toner produced by a suspension polymerization method and has an average particle diameter of about 5.8 μm. In order to modify the surface, silicon oxide of about 20 nm is adhered to the surface in an amount of about 1.5% of the toner weight. The weight was 50g. The average particle diameter of the toner t is a volume average particle diameter measured with a laser diffraction particle size distribution analyzer LS-230 manufactured by Beckman Coulter.

  The cartridge 8 as described above realizes easy maintenance of the image forming apparatus 100 because the user can replace it with a new one when the toner t in the developing device 1 runs out. The exchanged cartridge 8 is collected by the manufacturer and recycled or discarded. According to the present invention, the developing blade 2 inside the developing device 1 in the cartridge 8 thus collected can be recycled without any special cleaning or repair (described later).

  The developing device 1 includes a developing container 3, a developing blade 2, a stirring member 5, a supply roller 6, and a developing roller 7. A toner t is accommodated in the developing container 3. The toner t stirred by the rotation of the stirring member 5 is conveyed to the vicinity of the supply roller 6 and is pressed against the surface of the developing roller 7 by the supply roller 6 and adheres thereto. The toner t adhering to the developing roller 7 is regulated in layer thickness by the developing blade 2 and has a specific charge of about 30 μC / g, and is rotated and used as it is for development. The toner t that has not moved to the photosensitive drum 11 by development is peeled off by the supply roller 6. This series of operations is continuously repeated.

  The developing roller 7 has a metal core having a diameter of 6 mm and a conductive elastic body. The conductive elastic body has a conductive silicon rubber having a thickness of less than 3 mm in the base layer, and a resin layer in which carbon black and resin particles having a thickness of about 30 μm are dispersed on the surface layer. As the material of the developing roller 7, NBR, hydrin rubber, urethane rubber, or the like can be used. The surface hardness is about 65 degrees with an Asker rubber hardness tester C type (load 1 kg). The measurement is a value measured with a weight of 1 kg using an Asker rubber hardness meter C type manufactured by Kobunshi Keiki Co., Ltd.

  The resistance value is about 1 MΩ. For the measurement, a metal rod having a diameter of 30 mm and longer than the developing roller 7 is brought into contact with the developing roller 7 with an intrusion amount of 30 μm. Then, the metal rod is rotated at a surface speed of 100 mm / sec, the developing roller 7 is driven to rotate, and a voltage of 100 V is applied. The current flowing at this time was measured with an ammeter and converted into a resistance value. The surface roughness Ra is about 0.1 μm. For the measurement, a surface roughness measuring device SE-30H manufactured by Kosaka Laboratory Ltd. was used.

  The developing roller 7 is pressed against the photosensitive drum 11 so that the intrusion amount is 100 μm. A bias voltage is supplied to the cored bar from the printer body. When performing development, the material of the photosensitive drum 11 is adjusted so that the charged potential of the photosensitive drum 11 is −500 V, and the potential of the exposed portion is −100 V, and the developing roller 7 is set to about −300 V. The electrostatic image can be developed by setting the potential to.

  The supply roller 6 has a core bar having a diameter of 6 mm and a sponge-like urethane rubber having a thickness of 3 mm. The supply roller 6 has a hardness of about 15 degrees and is in contact with the developing roller 7 with an intrusion amount of 1 mm.

  FIG. 3 is an exploded perspective view showing the configuration of the developing blade 2. The developing blade 2 includes a fixing member 2a, a leaf spring member 2b, and a contact member 2c. The fixing member 2a includes a substrate 2a-1, a pressing member 2a-2, and a screw 2a-3. The board | substrate 2a-1 is created by making the screw hole k1 in what bent 0.7 mm of stainless steel in the L shape. The pressing member 2a-2 is formed by similarly forming a screw hole k2 in stainless steel having a thickness of 0.7 mm.

  The leaf spring member 2b is formed by forming a screw hole k3 in a rectangular SUS plate having a thickness of 0.08 mm and a longitudinal length L2 of 27 mm. The base end of the plate spring member 2b is fixed by a fixing member 2a, and the length L1 (see FIG. 4) from the base end to the tip of the plate spring member 2b is set to 20 mm.

  The thickness of the leaf spring member 2b is preferably 0.06 mm to 0.12 mm for a metal such as phosphor bronze or SUS. In that case, the length from the fixing point by the fixing member 2a to the tip of the leaf spring member 2b is preferably 15 mm to 35 mm. Ideally, the pressing force by the leaf spring member 2b does not depend on the amount of bending, so the thickness is thin and the length from the fixed point to the tip is better. However, if an extremely thin object is bent greatly and used, it tends to become unstable and easily become hazy, so it is preferable to use it in the above range.

  The contact member 2c is provided in a substantially circular cross section so as to wrap the tip of the plate spring member 2b on the side opposite to the portion where the screw hole k3 of the plate spring member 2b is provided. By providing in this way, it is possible to suppress the joint between the contact member 2c and the leaf spring member 2b from being taken even when the friction due to the rotation of the developing roller 7 is very high. The material of the contact member 2c is urethane resin imparted with ionic conductivity, and the surface roughness Ra is about 0.08 μm.

  The material of the contact member 2c may be silicon resin or fluororesin, but is preferably selected from a plurality of viewpoints such as charge imparting property to the toner t and whether the toner t is deteriorated. Further, by imparting conductivity, the potential difference from the developing roller 7 can be controlled, and toner regulation and charge application can be made more appropriate. The radius of the circle of the contact member 2c was about 0.5 mm. If the radius of the circle is too large, the toner will be taken in too much, and if it is too small, it will be too restricted, so that the radius is preferably 0.3 mm to 1 mm.

  When assembling each of these members as the developing blade 2, the substrate 2a-1, the leaf spring member 2b, and the pressing member 2a-2 may be fixed to the screw holes of the developing container 3 with screws 2a-3 in this order. . The contact angle θ with the developing roller 7 is set to about 70 °. The contact angle θ will be described later.

  FIG. 4 is an enlarged cross-sectional view showing the configuration of the developing blade 2. The pressure applied between the developing blade 2 and the developing roller 7 will be described below with reference to FIG. The developing blade 2 includes a leaf spring member 2b that is fixed to the developing container 3 whose base end portion is a “developing device body”. The developing blade 2 is integrally formed with a substantially constant radius of curvature extending from one surface 2b1 (front surface) to the other surface 2b2 (back surface) of the plate spring member 2b. The abutting member 2c provided at the tip portion of the head. As shown in FIG. 4, the contact member 2 c of the developing blade 2 is pressed against and contacts the developing roller 7. The pressing force was set to about 30 g weight per 10 mm longitudinal width by adjusting the amount of contact of the contact member 2c into the developing roller 7.

  For the measurement of the pressing force, a stainless plate having a width of 30 cm and a thickness of 30 μm is bent, and a stainless steel having a width of 15 mm and a thickness of 30 μm is sandwiched therebetween. When this is inserted between the abutting member 2c and the developing roller 7 and the stainless steel plate sandwiched between them is pulled out, the force acting on the digital force gauge DS2 manufactured by Imada Co., Ltd. is measured. Converted.

  FIG. 5A is a cross-sectional view showing the shape of the developing blade 102 according to the comparative example. FIG. 5A shows a configuration using a contact member 2 c ′ having a square cross-sectional shape. With reference to FIG. 5A, the superiority of the contact member 2c having a circular cross-sectional shape will be described below.

  Assuming that the developing device 1 is used or stored for a very long period of several years, there is some plastic deformation even if the leaf spring member 2b is a metal. The solid line in FIG. 6A indicates the shape of the developing blade 102 when new, and the broken line in FIG. 6A indicates the shape of the developing blade 2 after long-term storage. The developing blade 102 has a straight shape as shown by a solid line when it is new, but is deformed without a pressing force to the developing roller 7 after long-term storage. In this case, if the plate spring member 2b is reversed and fixed to the fixing member 2a so as to be recycled, the plate spring member 2b is bent toward the developing roller 7 side.

  FIG. 5B is a cross-sectional view illustrating configurations of the developing blade 102 and the developing roller 7 according to the comparative example. As shown in FIG. 5B, when the plate spring member 2b after long-term storage is fixed to the fixing member 2a with the front and back reversed, the deformation remains in the vicinity of the fulcrum of the plate spring member 2b in the fixing member 2a. Therefore, the arrangement of the abutting surface that regulates the toner of the abutting member 2c ′ changes between the front surface and the back surface. In other words, when the front and back sides of the leaf spring member 2b after long-term storage are reversed, the contact member 2c is further pressed against the developing roller 7.

  FIG. 5C is an enlarged cross-sectional view illustrating configurations of the developing blade 102 and the developing roller 7 according to the comparative example. As shown in FIG. 5C, at the time of actual toner regulation, the toner t is conveyed as the developing roller 7 rotates in the direction of the arrow. The major difference in toner regulation is the size of the entrance for toner t. Compared to a new product (solid line), it has become wider after long-term storage (broken line). Even if the difference is only a few tens of μm, the behavior of the toner t in the vicinity of the frontage directly affects the uniformity and stability of toner regulation, so many patent documents and non-patent documents have been proposed in the past. Even products that are mass-produced are strictly controlled.

  On the other hand, as in the present embodiment, if the cross section has a constant curvature at least from the front surface contact portion to the back surface contact portion of the contact member 2c, the above change cannot occur. As described above, in order to make the toner regulation less susceptible to slight plastic deformation of the leaf spring member 2b due to long-term use or long-term storage, it is preferable that the cross-sectional shape of the contact member has a constant curvature.

  FIG. 6 is an enlarged cross-sectional view showing a contact state between the developing blade 2 and the developing roller 7. The contact angle θ between the developing blade 2 and the developing roller 7 will be described below with reference to FIG. The contact angle θ here is an angle formed by a virtual straight line PR passing through two points of the rotation center P and the contact center R of the developing roller 7 and a virtual straight line Q along the leaf spring member 2b. It is. Note that the virtual straight line PR and the virtual straight line Q are displayed as “straight line PR” and “straight line Q” in FIG. 6 and subsequent figures.

  The contact portion center R is the center of the contact portion length k where the contact member 2c and the surface of the developing roller 7 are in contact. Further, since the contact member 2c is in contact with the developing roller 7 with an intrusion amount of about 1 mm, a slight bend occurs. Therefore, when the bending is large and it is difficult to determine the contact angle θ, the virtual straight line Q is approximated by a straight line connecting the straight line of the leaf spring member 2b and the intersection G of the contact member 2c and the center J of the contact member 2c. May be. The abutting direction of the developing blade 2 is preferably counter abutting because of the strength of the joint surface between the abutting member 2c and the leaf spring member 2b, and the case of counter abutting will be described below.

  FIG. 7 is a conceptual diagram showing a state in which the leaf spring member 2b of the developing blade 2 contacts the developing roller 7 at different contact angles. The virtual straight lines A, B, and C in FIG. 7 are obtained by fixing the virtual straight line PR described above with reference to FIG. 6 and arranging the developing blades 2 in which the angle formed by the virtual straight line Q along the developing blade 2 is changed. Show. When the leaf spring member 2b is attached upside down, the contact surface of the contact member 2c is reversed with each virtual straight line as the axis of symmetry. The virtual straight lines A, B, and C are indicated as “straight line A”, “straight line B”, and “straight line C” in FIG.

  When the front and back sides of the leaf spring member 2b are reversed with respect to the virtual straight line A, the contact portion position a, which is the position of the contact portion, moves to the contact portion position a ′, and the contact portion position b is Move to contact position b ′. The contact portion positions a, a ′, b, and b ′ are indicated as “position a”, “position a ′”, “position b”, and “position b ′” in the drawing. However, here, the contact part position b and the contact part position b 'are the same position and do not change. That is, when the leaf spring member 2b is attached upside down, the first surface 2c1 when the front surface of the contact member 2c is used and the second surface 2c2 when the back surface is used partially overlap as a contact portion. . In this case, it is not preferable because the influence of the fixed matter accumulated at the contact portion position b when using the front surface is received at the contact portion position b 'when using the back surface. Therefore, if the angle θa is set to be small, the “problem where the contact portion position b is shared by the contact portion position b ′ (overlapping the front and back)” is avoided.

  Accordingly, the arrangement of the developing blade 2 is determined as follows. First, the surface of the contact member 2c located on one surface 2b1 of the leaf spring member 2b is the first surface 2c1, and the surface of the contact member 2c located on the other surface 2b2 of the leaf spring member 2b is the second surface. 2c2. Then, it is assumed that the developing blade 2 is fixed to the developing container 3 so that the one surface 2b1 and the other surface 2b2 of the leaf spring member 2b are reversed.

  In this case, the second contact portion positions b and b ′ at which the second surface 2c2 of the contact member 2c contacts the developing roller 7 are the first contact positions b and b ′ at which the first surface 2c1 of the contact member 2c contacts the developing roller 7. The following can be said in relation to the position of a contact portion a, a ′. That is, the second contact portion positions b and b ′ are related to the first contact portion positions a and a ′ so that the positions on the surface of the developing roller 7 do not overlap with each other. An arrangement angle of the blade 2 is set.

  In FIG. 7, the region from the state of the virtual straight line A to the vertical state rotated clockwise about the center J of the contact member 2 c (“contact portion overlap”) It is assumed that it is arranged in a region described as “region X”. In this case, the contact portion position b may be shared by the contact portion position b '(overlapping the front and back).

  On the other hand, the region (region Y) from the state of the virtual straight line A to the state of the virtual straight line C after the leaf spring member 2b rotates counterclockwise around the center J of the contact member 2c. And “plate spring member axial region Z”). In this case, the “problem where the abutting portion position b is shared by the abutting portion position b ′ (overlapping both sides upside down)” does not occur. The region Y is a region between the virtual straight line A and the virtual straight line B.

  FIG. 8 is a conceptual diagram showing the force that acts at the moment when a static friction force much greater than the force with which the developing blade 2 presses the developing roller 7 is generated. Although the frictional force is generated at the contact portion, here, the force applied to the intersection of the leaf spring member 2b and the contact member 2c is described as the frictional force.

  As described above, when the leaf spring member 2b is disposed at the position of the imaginary straight line A in FIG. 7, when the friction between the contact member 2c and the developing roller 7 is large, the leaf spring member 2b is turned over. The problem of plastic deformation is likely to occur. The direction of the frictional force is considered to be the tangential direction of the developing roller 7. However, since the contact member 2c is sufficiently smaller than the developing roller 7, the direction of the force is considered to be θ = 90 °. If the static friction is quickly changed to dynamic friction, large deformation of the leaf spring member 2b and the stationary still state can be avoided, but strong static friction continues until the sticking between the contact member 2c and the developing roller 7 is eliminated. End up.

  There are two situations where very large static friction acts on the contact member 2c. One is a case where the contact member 2c comes into contact with the surface of the developing roller 7 without using the toner t when it is new. The other is when the toner is almost exhausted after use or when the toner runs out. In both cases, the developing roller 7 and the developing blade 2 are directly rubbed without the toner t interposed therebetween. In particular, the developing roller 7 used in the contact development system is preferably one having rubber elasticity because it is necessary to ensure stable toner t transfer, that is, development by securing a contact nip width with the photosensitive drum 11. . Generally, a rubber elastic body has a tack property, and when it is rubbed, a large frictional force is generated.

  A means generally used as means for avoiding this large static frictional force is to apply toner t to the surface of the developing roller 7 in advance. Since the toner t is very small compared to the contact member 2c and is almost spherical, it easily rolls when entering between two objects, and can avoid high friction as a lubricant.

  However, the means for applying the toner t to the developing roller 7 in advance is highly effective if the developing device 1 is new. However, when the purpose is to recycle as in the present invention, it is not necessary to consider until after the toner t is used up. Must not. That is, even in a situation where the toner t is difficult to function as a lubricant, the developing blade 2 must be avoided from being fatally damaged by recycling. For this purpose, it is preferable to perform toner regulation with a contact angle θ such that a virtual straight line B and a virtual straight line C, which will be described below, are used as symmetrical axes.

  FIG. 9 is a conceptual diagram showing a state in which the leaf spring member 2b of the developing blade 2 is in contact with the virtual straight line PR at a contact angle of 86 °. As shown in FIG. 9, at the position of the imaginary straight line B, the contact angle θ of the developing blade 2 is θb = 86 °. In this case, it is not necessary to consider the problem that the contact member 2c is shared between the front and back sides. Further, by setting the contact angle θ in this way, even in a situation of receiving a strong static frictional force, the moment is received by receiving in the axial direction of the leaf spring member 2b (the direction perpendicular to the direction normally used as the leaf spring). Therefore, it is possible to prevent the deformation of the leaf spring member 2b. That is, by setting the contact angle θ <90 °, a strong force due to static friction may be received in the axial direction of the leaf spring member 2b.

  Therefore, the following conditions are desirable. That is, the developing blade 2 is in counter contact with the rotation direction of the developing roller 7. Further, a virtual straight line PR that is a “first virtual straight line” passing through the rotation center P of the developing roller 7 and a contact part center R that is the center of the contact part, and a virtual straight line Q along the leaf spring member 2 b are formed. The arrangement angle to be set is set to an angle smaller than 90 °.

  FIG. 10 is a conceptual diagram showing a state in which the leaf spring member 2b of the developing blade 2 is in contact with the virtual straight line PR at a contact angle of 40 °. As shown in FIG. 10, at the position of the imaginary straight line C, there is a limit where the developing roller 7 and the developing blade 2 can be arranged. That is, if the angle is set smaller than the contact angle θc, it is not preferable because the contact is performed twice or the contact member 2c is floated to be contacted by the leaf spring member 2b.

  Therefore, the contact angle θ is preferably set limit angle θc ≦ θ <90 °. In the case of the combination of the developing roller 7 and the contact member 2c as in the present embodiment, the set limit angle θc is θc = 37.4 ° when theoretically calculated as the contact between the circle and the circle. However, in reality, θc = about 40 ° because it is also affected by the thickness of the toner layer, the crushing condition of the contact member 2c of the developing roller 7, and the bending condition of the leaf spring member 2b. However, when the charged toner on the developing roller 7 and the leaf spring member 2b come close to each other, the toner t adheres and accumulates on the leaf spring member 2b due to electrostatic force, and the toner coat may be disturbed to some extent. It is preferable to keep them apart. Therefore, when the contact angle θ is about 70 ° as in this embodiment, the developing blade 2 can be recycled without such a concern.

  FIG. 11A is a cross-sectional view illustrating a configuration of the developing blade 22 that is a “toner regulating member” included in the developing device according to the second embodiment. Regarding the configuration and effects of the developing blade 22 of the second embodiment that are the same as those of the developing blade 2 of the first embodiment, the same reference numerals are used and description thereof is omitted as appropriate. Since the second embodiment can be applied to the developing device 1, the cartridge 8, and the image forming apparatus 100 as in the first embodiment, the description of the developing device, the cartridge, and the image forming apparatus is omitted. A characteristic of the configuration of the developing blade 22 of the second embodiment is that the imaginary straight line that is the “second imaginary straight line” toward which the tip of the leaf spring member 2b is directed is removed from the cross-sectional center (center K) of the contact member 2c. It is a point.

  As shown in FIG. 11A, the developing blade 22 includes a fixing member 2a, a leaf spring member 2b, and a contact member 2c. However, the position where the tip of the leaf spring member 2b is arranged on the contact member 2c is different. With such a configuration, when the front and back of the developing blade 22 are reversed, the phenomenon that the pressing force due to the plastic deformation of the leaf spring member 2b increases is alleviated.

  In the first embodiment, as described with reference to FIG. 5, when the developing blade 2 is used for a long time, the leaf spring member 2b is slightly plastically deformed. When the plastically deformed developing blade 2 is fixed with its front and back reversed, the contact state with the developing roller 7 changes. From the first contact state in which the first surface 2c1 of the contact member 2c of the developing blade 2 is in contact with the developing roller 7, the second surface 2c2 of the contact member 2c of the developing blade 2 plastically deformed. Is changed to the second contact state in contact with the developing roller 7, the following changes occur.

  That is, in the first contact state, even if the developing blade 22 is pressed against the developing roller 7 with an appropriate pressing force, in the second contact state, the leaf spring member 2b is deformed. Therefore, the developing blade 22 is pressed against the developing roller 7 with a slightly strong pressing force. When such a developing blade 22 pressurizes the developing roller 7 with a large pressure, it leads to deterioration of the toner, which is not preferable.

  Therefore, the developing blade 22 is formed and set so that the tip of the leaf spring member 2b does not face the center K of the contact member 2c. In other words, the tip of the leaf spring member 2b is provided at a position deviated from the center K of the contact member 2c.

  FIG. 11B is an enlarged cross-sectional view showing the configuration of the tip of the developing blade 22 when the surface is in contact with the developing roller 7. FIG. 11B corresponds to the solid line in FIG. As shown in FIG. 11B, for example, the tip of the leaf spring member 11b of the developing blade 22 passes a position that is 2 mm away from the center K of the contact member 2c with respect to the inside of the contact member 2c. So that it is fixed.

  For example, the contact member 2c is formed with a diameter of 1 mm in a direction orthogonal to the axial direction. And the front-end | tip of the leaf | plate spring member 2b exists in the position divided by 0.7 mm and 0.3 mm in the direction orthogonal to an axial direction through the center K of the contact member 2c. In this way, when the second surface 2c2 is used (see FIG. 11C), the amount of bending of the leaf spring member 2b is reduced, so that the pressure increase due to plastic deformation can be reduced. As shown in FIG. 11B, when new, the developing blade 22 has the first surface 2c1 of the contact member 2c on the side away from the tip of the leaf spring member 2b in contact with the developing roller 7. .

  FIG. 11C is an enlarged cross-sectional view showing the configuration of the tip of the developing blade 22 when the back surface is in contact with the developing roller 7. FIG. 11C corresponds to the broken line diagram of FIG. As shown in FIG. 11 (c), after being used for a long period of time, the developing blade 22 is disposed so that the front and back are reversed, and the contact member 2c on the side closer to the tip of the leaf spring member 2b. The second surface 2c2 is in contact with the developing roller 7.

  As can be seen from FIGS. 11 (b) and 11 (c), the developing blade 22 is used in a state where the tip of the leaf spring member 2b is located outside the center K when it is new, and the leaf spring member 2b is recycled. The developing blade 22 is used in a state in which the tip of is located inside the center K. In this way, the pressing force is reduced by pressing the developing roller 7 with the contact surface of the contact member 2c that is close to the tip of the leaf spring member 2b during recycling.

  FIG. 12 is a cross-sectional view illustrating a configuration of the developing blade 32 that is a “toner regulating member” included in the developing device according to the third embodiment. Among the configurations of the developing blade 32 of the third embodiment, the same configurations and effects as those of the developing blades 2 and 22 of the first and second embodiments are denoted by the same reference numerals and description thereof is omitted as appropriate. Since the third embodiment can be applied to the developing device 1, the cartridge 8, and the image forming apparatus 100 similar to those in the first embodiment, the description of the developing device, the process cartridge, and the image forming apparatus is omitted. A characteristic of the configuration of the developing blade 32 of the third embodiment is that when the first surface 2c1 of the contact member 2c first contacts the developing roller 7 in preference to the second surface 2c2 of the contact member 2c, The conductive fine particle 50 is previously applied to the second surface 2c2 when the first surface 2c1 is used for the first time.

  When a new developing device is used for a long period of time, the rear surface of the developing blade 32 is subjected to toner collision. Therefore, after a long period of use, electrostatically charged toner and components in the toner adhere to the surface of the contact member of the developing blade 32. Such deposits are not a problem during the developing operation, but are problematic in that they are difficult to clean when the developing blade 32 is recycled. If this deposit is only a component derived from toner, it can be used without cleaning. However, for example, in an environment where fibrous dust or dust adheres due to static electricity when the leaf spring member 2b is removed and replaced on the back surface, the adhering matter is between the developing roller 7 and the contact member 2c. The toner is regulated while being sandwiched between the two, and the portion becomes defective. In order to solve this problem, the developing blade 32 is configured as follows.

  As shown in FIG. 12, in the developing blade 32, conductive fine particles 50 are applied in advance on the back surface of the contact member 2c. In this way, the conductive fine particles 50 serve as spacers, the contact area between the toner and the contact member 2c is reduced, and the adhesion of toner and toner-derived components is reduced. Accordingly, the amount of static electricity due to the toner is reduced, and the amount of dust and the like is reduced. Furthermore, the effect is high because static electricity is easily released by the charge removing action of the conductive fine particles. Note that the conductive fine particles 50 can be effective in a very small amount because the back surface of the contact member 2c only needs to be covered with about one layer.

  Particularly suitable as the conductive fine particles 50 are metal oxides (such as titanium oxide, tin oxide, zinc oxide, molybdenum oxide, potassium titanate, antimony oxide, and indium oxide). These conductive particles may be used after being subjected to a coupling treatment.

  As a method of applying the conductive fine particles 50 to the contact member 2c, the conductive fine particles may be tangled with a brush, a brush, a brush, or the like, and then lightly rubbed in the longitudinal direction of the contact member 2c. As long as it can be applied to the back surface of the contact member 2c at a minimum, there is no problem even if about one particle layer adheres to other portions.

The conductive fine particles 50 preferably have a resistivity of about 10 ² to 10 ⁶ Ω · cm and an average volume particle size of about 0.2 μm to 1 μm. If the resistivity is too low, an image defect may occur due to an applied bias at the time of development. If the resistivity is too high, charging tends to occur and the original effect is reduced. If the particle size is too small, the contact area increases and the function as a spacer is weakened. If the particle size is too large compared to the toner, the contact member 2c is easily peeled off.

Next, a method for measuring the resistivity of the conductive fine particles 50 will be described. 0.5 g of conductive fine particles 50 are put in a cylindrical container with an area of 2 cm ² and sandwiched between electrodes from above and below, and after applying a voltage of 100 V while applying a pressure of 15 kgf, the current value when the voltage settles to a substantially constant value is Calculated in terms of resistivity.

  According to such a configuration, the back surface of the contact member 2c can be kept in a state preferable for recycling even after being used for a long time.

  As described above, according to the configurations of the first to third embodiments, even when the developing blade 2 is used for a long period of time, the developing blade 2 can be recycled without special repair or cleaning. It becomes possible.

  Further, according to the configuration of the second embodiment, the developing blade 22 is used with the tip of the leaf spring member 2b farther from the developing roller 7 than the center K when new, and the tip of the leaf spring member 2b is closer to the center K when recycling. Also, the developing blade 22 is used in a state close to the developing roller 7. As a result, the pressure applied to the developing roller 7 by the developing blade 22 is reduced after recycling.

  Further, according to the configuration of the third embodiment, the developing blade 32 is used in a state where the conductive fine particles 50 are previously applied to the second surface 2c2 when the first surface 2c1 is used for the first time. As a result, it is easy to maintain the state of the second surface 2c2 until recycling.

DESCRIPTION OF SYMBOLS 1 Developing device 2, 22, 32 ... Developing blade (toner regulating member)
2b Leaf spring member 2b1 One surface 2b2 The other surface 2c Contact member 2c1 First surface 2c2 Second surface 3 Developing container (developing device main body)
7 Developing roller 7 (toner carrier)

Claims (6)

A toner carrier for carrying toner;
A toner regulating member that regulates the amount of toner carried on the toner carrier,
The toner regulating member is
A leaf spring member whose base end is fixed to the developing device body;
A contact member provided at the front end of the leaf spring member, which is integrally formed with a substantially constant radius of curvature from one surface to the other surface at the front end of the leaf spring member; Have
When the surface of the contact member located on the one surface of the leaf spring member is the first surface and the surface of the contact member located on the other surface of the leaf spring member is the second surface In addition,
When the toner regulating member is fixed to the developing device main body so that the one surface and the other surface of the leaf spring member are reversed,
The second contact portion where the second surface of the contact member contacts the toner carrier is a first contact portion where the first surface of the contact member contacts the toner carrier. Accordingly, an arrangement angle of the toner regulating member with respect to the toner carrier is set so that positions thereof do not overlap on the surface of the toner carrier. The toner regulating member is in counter contact with the rotation direction of the toner carrier;
The arrangement angle is an angle formed by a first virtual straight line passing through the rotation center of the toner carrier and the center of the contact portion and the leaf spring member, and is set to an angle smaller than 90 °. The developing device according to claim 1.   3. The developing device according to claim 1, wherein the second imaginary straight line toward which the distal end portion of the leaf spring member is directed is deviated from a cross-sectional center of the contact member.   When the first surface of the contact member first contacts the toner carrier in preference to the second surface of the contact member, the first surface is brought into contact with the second surface when the first surface is used for the first time. The developing device according to claim 1, wherein conductive fine particles are applied in advance. A developing device according to any one of claims 1 to 4, comprising:
A process cartridge which is detachable from an image forming apparatus main body. An image carrier;
A developing device according to any one of claims 1 to 4,
An image forming apparatus comprising:

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