JP2013057797A - Development device and image forming apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a development device capable of solving the problem that a charge amount of a developer layer reduces with the lapse of time and stabilizing the charge amount of the developer layer, and to achieve an image forming apparatus having the development device.SOLUTION: The development device includes: a developer tank; a developing roller for supplying toner to a photosensitive drum; and a toner layer regulation blade. The toner layer regulation blade has an elastic body at one end in contact with the developing roller, and has, at the other end, a blade angle adjustment mechanism capable of adjusting an angle of the toner layer regulation blade, relative to a horizontal direction. Before and after the angle of the toner layer regulation blade is changed, a contact position, on the toner layer regulation blade, being in contact with the developing roller does not change, and a direction in which pressing force of the toner layer regulation blade is applied does not change relative to a rotation axis of the developing roller.

Description

  The present invention relates to a developing device mounted in an image forming apparatus employing an electrophotographic system, and more particularly a non-magnetic one-component developing device, particularly a developing device for performing non-contact development, and more particularly a rigid body such as a metal. The present invention relates to a developing device using a developer carrying member and an image forming apparatus including the developing device.

  In an image forming apparatus that employs an electrophotographic system, a latent image formed on the surface of a photoconductor is developed by supplying toner as a developer component from a developing device and developing it. A toner image is formed, the toner image is further transferred onto a recording paper as a transfer medium, and the toner image transferred onto the recording paper is fixed to form a robust recording image.

  In recent years, with the widespread use of color inkjet image forming apparatuses, image forming apparatuses using an electrophotographic system are also required to be reduced in size and price. Under such circumstances, as a developing device for electrophotography, a non-magnetic one-component developing system that is simple in structure and capable of being miniaturized is useful, and development of an improved technique is ongoing. In this non-magnetic one-component development system, the developer is moved to the developing roller and conveyed in the developing device, and the developer is frictionally charged by the developer regulating member and at the same time the thickness of the developer layer is regulated, The developer in a thin film state is developed by electric force.

  Here, in order to stabilize the image quality, it is required that the developer on the developing roller is stably conveyed and the charge amount and the adhesion amount are stabilized. However, there has been a problem in that the charge amount and the adhesion amount of the developer on the developing roller vary due to various causes during the usage of the developing device, and the transferred image quality deteriorates.

  For example, Patent Document 1 discloses a developing device that reduces toner aggregation and accumulation of foreign matters that occur over time.

  FIG. 4 is a cross-sectional view of the developing device of Patent Document 1. The developing device of Patent Document 1 includes a developing roller 101, a thin layer forming unit 102, and a toner layer thickness detection sensor 103. The thin layer forming unit 102 includes an elastic blade 104 such as rubber, a blade fixing member 105, and a developing unit. The dose adjustment mechanism 106 is configured. The developer amount adjusting mechanism 106 is a developer for toner formed on the surface of the developing roller 101 by the projection 107 provided at the end of the blade fixing member 105 moving along the long hole 108 provided in the case (not shown). Adjust the amount. The elongated hole 108 is provided so as to draw an arc having a radius R with the contact point 110 between the elastic blade 104 and the developing roller 101 as the center.

  At this time, since the elastic blade 104 is moved while the free length L and the deflection amount α of the elastic blade 104 are kept constant, the pressing force of the elastic blade 104 can be kept constant. As a result, only toner flow during the printing operation is changed to reduce toner aggregation and accumulation of foreign matters that occur over time, thereby preventing print quality deterioration such as white stripes.

JP 2003-215911 A (published July 30, 2003)

  However, in the technique shown in Patent Document 1, since the elastic blade 104 rotates around the contact point 110, even if the free length L and the deflection amount α are kept constant and the pressing force remains constant, the pressing force remains constant. This direction changes. As a result, a change occurs in the pressing force applied by the elastic blade 104 in the direction of the rotation axis of the developing roller 101, resulting in variations in the charge amount and adhesion amount of toner, and the transferred image quality deteriorates. There is. Further, the toner layer is regulated locally so that the elastic blade 104 is bent so that the contact point 110 between the elastic blade 104 and the developing roller 101 does not change. There is also a problem that the stability of the quantity becomes worse.

  SUMMARY An advantage of some aspects of the invention is to realize a developing device capable of stabilizing the charge amount of a developer and an image forming apparatus including the developing device.

  In a developing device including a developer tank, a developer carrier for supplying developer to the developer carrier, and a developer regulating member, the development regulating member includes an elastic body at one end in contact with the developer carrier and the other end. A developer regulating member angle adjustment mechanism capable of adjusting the angle of the developer regulating member with respect to the horizontal direction is attached, and the developer regulating member is in contact with the developer carrying member before and after the angle of the developer regulating member is changed. The contact position is not changed, and the direction in which the pressing force of the developer regulating member is applied does not change with respect to the rotation axis of the developer carrying member.

  The developer regulating member angle adjusting mechanism includes a protrusion and an angle adjusting hole. The protrusion is fixed to the developer regulating member, and the angle adjusting hole is developed so as to draw an arc around the rotation axis of the developer carrying member. It may be provided in the agent tank. The angle of the developer regulating member may be changed in a plurality of stages according to the charge amount of the developer layer, the number of rotations of the developer carrier, or the number of recording sheets on which an image is formed. Further, the surface portion of the elastic body of the developer regulating member may be in contact with the developer carrying body. An image forming apparatus including the developing device may be configured.

  According to the present invention, even if the charge amount of the developer layer decreases with time, the developer that adjusts the angle of the developer regulating member with respect to the developer carrying member and can be in the space upstream of the developer regulating member By adjusting the amount of accumulation, the charge amount of the developer layer can be stabilized.

1 is a cross-sectional view of an image forming apparatus illustrating an embodiment of the present invention. It is sectional drawing of the developing device showing one Example of this invention. It is sectional drawing of the developing device showing the position change of the developer control member of this invention. 10 is a cross-sectional view of a developing device according to Patent Document 1. FIG.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram showing the configuration of the image forming apparatus of the present invention. The image forming apparatus of FIG. 1 includes a photosensitive drum 11 that is a developing carrier, a charging device 12, an exposure device 13, a developing device 14, a transfer device 15, a cleaning device 16, a charge eliminating device 17, and a fixing device 18. Is done.

  The photosensitive drum 11 is rotatably supported by an image forming apparatus main body (not shown) and is driven to rotate in the direction of the arrow by a driving means (not shown). The drive means includes, for example, an electric motor and a reduction gear, and rotates the photosensitive drum 11 at a predetermined peripheral speed by transmitting the driving force to the conductive support that forms the core of the photosensitive drum 11. Drive. The charging device 12, the exposure device 13, the developing device 14, the transfer device 15, the cleaning device 16, and the charge eliminating device 17 are rotated in this order along the outer peripheral surface of the photosensitive drum 11. It is provided from the direction upstream to the downstream.

  The charging device 12 is a charging unit that charges a part of the outer peripheral surface of the photosensitive drum 11 to a predetermined potential in the entire axial direction, and charges the entire periphery of the photosensitive drum 11 by rotating. Can do. Specifically, the charging device 12 is realized by, for example, a charger wire mechanism such as corotron or scorotron, or a contact-type charging roller or charging brush. In this embodiment, the surface potential of the photosensitive drum 11 is charged to about −600 V, but it is set according to the material of the photosensitive drum 11 and the usage situation.

  The exposure device 13 is an exposure unit including, for example, a semiconductor laser as a light source, and irradiates the photosensitive drum 11 with light such as a laser beam output from the light source, whereby the outer peripheral surface of the charged photosensitive drum 11 is exposed. Is set to about 0 V, and exposure is performed according to image information. The exposure is performed by repeatedly scanning the semiconductor laser in the main scanning direction in the direction in which the rotation axis of the photosensitive drum 11 extends, and accordingly, electrostatic latent images are sequentially formed on the surface of the photosensitive drum 11.

  The developing device 14 is a developing unit that develops an electrostatic latent image formed on the surface of the photosensitive drum 11 by charging and exposure. The developing device 14 is provided in close proximity to the photosensitive drum 11 and has an outer peripheral surface of the photosensitive drum 11. The toner as a developer is supplied to the toner, and the toner is attached in accordance with the electrostatic latent image by the potential gap on the photosensitive drum 11 to visualize or develop the electrostatic latent image.

  Further, the developed toner image on the photosensitive drum 11 is transferred by the transfer device 15 onto a recording paper 19 that is a recording medium conveyed and supplied between the photosensitive drum 11 and the transfer device 15. The transfer device 15 may be a charging device such as a corotron that applies a charge having a polarity opposite to that of the toner to the recording paper 19, or may be a conductive contact transfer roller biased to have a polarity opposite to that of the toner.

  After the transfer process, the toner remaining untransferred on the photosensitive drum 11 is removed and collected from the photosensitive drum 11 by the cleaning device 16. The cleaning device 16 includes a cleaning blade 20 that peels off toner remaining on the outer peripheral surface of the photosensitive drum 11, and a recovery casing 21 that stores toner peeled off by the cleaning blade 20.

  After the cleaning process, the photosensitive drum 11 is irradiated with light from the entire surface by a static elimination device 17 such as a static elimination lamp, and the residual potential is eliminated. Then, repeated charging, exposure, development, transfer, cleaning, and static elimination processes are performed.

  On the other hand, the recording paper 19 to which the toner image has been transferred in the transfer process is conveyed to the fixing device 18, where the toner image is fixed on the recording paper 19 and finally the image fixed on the recording paper 19 is obtained. can get. As the fixing device 18, the toner on the recording paper 19 is heated by heat and pressure by passing the recording paper 19 between a heating roller heated to a high temperature by a built-in heat lamp and a pressure roller facing the heating roller. It is possible to use a method of melting and fixing on the recording paper 19.

  The image forming operation by this image forming apparatus is performed as follows. First, when the photosensitive drum 11 is rotationally driven in the direction of the arrow by the driving means, the surface of the photosensitive drum 11 is uniformly charged to a predetermined positive or negative potential by the charging device 12.

  Next, light corresponding to image information is irradiated from the exposure device 13 to the surface of the photosensitive drum 11. With this exposure, the surface charge of the portion irradiated with light is removed in accordance with the amount of exposure light, and the surface potential of the portion irradiated with light and the surface potential of the portion not irradiated with light are exposed. An electrostatic latent image is formed by the difference.

  Next, toner is supplied from the developing device 14 to the surface of the photosensitive drum 11 on which the electrostatic latent image is formed, the electrostatic latent image is developed, and a toner image is formed.

  In synchronization with the exposure of the photosensitive drum 11, the recording paper 19 is conveyed and supplied between the photosensitive drum 11 and the transfer device 15. The transfer device 15 applies a charge having a polarity opposite to that of the toner to the supplied recording paper 19, and the toner image formed on the surface of the photosensitive drum 11 is transferred onto the recording paper 19.

  The recording paper 19 to which the toner image has been transferred is conveyed to the fixing device 18 by the conveying means, and is heated and pressed when passing through the contact portion between the heating roller and the pressure roller of the fixing device 18, so that the toner image is transferred. The image is fixed on the recording paper 19 and becomes a robust image. The recording paper 19 on which the image is formed in this manner is discharged to the outside of the image forming apparatus by the conveying means.

  On the other hand, the toner remaining on the surface of the photosensitive drum 11 after the transfer of the toner image by the transfer device 15 is separated from the surface of the photosensitive drum 11 by the cleaning device 16 and collected. The charge on the surface of the photosensitive drum 11 from which the toner has been removed in this manner is removed by the light from the charge eliminating unit 17, and the electrostatic latent image on the surface of the photosensitive drum 11 disappears. Thereafter, the photosensitive drum 11 is further rotationally driven, and a series of operations starting from charging is repeated to continuously form images.

  Next, the developing device equipped with the developer regulating member according to the present invention will be described.

  FIG. 2 is a cross-sectional view showing a configuration of the developing device 14 shown in FIG. The developing device 14 includes a developer tank 30, a developing roller 31, a toner supply roller 32, a toner layer regulating blade 33 that is a developer regulating member, a toner stirring roller 34, and a toner transport roller 35.

  The developing roller 31 as a developer carrying member faces the photosensitive drum 11 and is rotatably supported by an image forming apparatus main body (not shown), and is driven to rotate in the direction of an arrow by a driving unit. A toner supply roller 32 that is a developer supply member is pressed against the developing roller 31, and the toner supply roller 32 supplies toner that is a non-magnetic one-component developer onto the developing roller 31. The rotation direction of the toner supply roller 32 is the same as that of the developing roller 31, that is, the moving directions of the surfaces of both rollers in the portion facing the developing roller 31 are opposite to each other. A voltage is applied to the toner supply roller 32 from a bias power source (not shown), and the voltage acts in a direction to electrically push the toner toward the developing roller 31. For example, if the toner is a negative toner, A larger bias voltage is applied to the negative electrode side.

  The toner is frictionally charged by the toner supply roller 32, is supplied to the developing roller 31 by a bias voltage, and is conveyed to a position where the toner layer regulating blade 33 contacts by the rotation operation of the developing roller 31.

  The toner layer regulating blade 33 which is a developer regulating member is composed of a thin metal plate having a spring property, urethane rubber 37 which is an elastic body, and a blade fixing member 38, and urethane which is an elastic body at the tip of the metal sheet metal. A rubber 37 is integrated, and at the other end, a blade is sandwiched by a blade fixing member 38 composed of a set of sheet metal, and is fixed by a screw. The toner layer regulating blade 33 elastically presses the surface of the urethane rubber 37 against the developing roller 31 due to the spring property of the metal sheet metal, and causes the toner on the developing roller 31 to pass through a predetermined set pressure or set position. A toner layer that is a developer layer is formed by regulating the charge amount and the adhesion amount. By pressing and contacting the surface portion F of the urethane rubber 37 against the developing roller 31, the charge amount and adhesion amount of the toner layer can be stabilized.

  The toner layer regulated to a predetermined charge amount and adhesion amount is conveyed to a portion facing the photosensitive drum 11 on which the electrostatic latent image is formed. The undeveloped toner on the developing roller 31 returns to the developer tank 30 through the leakage prevention sheet 36 below the developing roller 31 as the developing roller 31 rotates.

  The leakage prevention sheet 36 is a sheet that mechanically contacts the developing roller 31. However, a conductive sheet is used, and an electrical bias is applied to the developing roller 31 to positively remove the undeveloped toner. It is also possible to have the effect of The toner thus returned to the developing device is scraped off from the surface of the developing roller 31 by the toner supply roller 32 and is collected in the developer tank 30.

  The collected toner is agitated with new toner by the toner agitation roller 34, and is again supplied and conveyed near the developing roller 31 by the toner conveyance roller 35. The toner stirring roller 34 and the toner transport roller 35 have wings made of a thin resin, for example, PET (Polyethylene terephthalate), provided around the rotation shaft.

  The configuration of the developing device 14 includes a blade angle adjusting mechanism 50 that is a developer regulating member angle adjusting mechanism that adjusts the position and angle of the toner layer regulating blade 33. The blade angle adjustment mechanism 50 includes a protrusion 39 and an angle adjustment hole 40. The protrusion 39 is fixed to the blade fixing member 38, and the angle adjustment hole 40 is provided in the developer tank 30. The angle adjustment hole 40 is provided so as to draw an arc with the rotation axis of the developing roller 31 as the center, and the protrusion 39 can be moved along the angle adjustment hole 40 and fixed at a plurality of predetermined positions. be able to.

  FIG. 3 is a cross-sectional view showing the configuration of the toner layer regulating blade 33 provided with the blade angle adjusting mechanism 50. FIG. 3A shows the configuration of the toner layer regulating blade 33 at the initial position, and FIG. 3B shows the configuration of the toner layer regulating blade 33 after the angle adjustment. With the configuration of the blade angle adjusting mechanism 50, the toner layer regulating blade 33 can change the position with respect to the developing roller 31 and the angle with respect to the horizontal direction while maintaining a certain amount of bending. Further, the contact position P of the urethane rubber 37 in contact with the surface of the developing roller 31 does not change before and after the position and angle of the toner layer regulating blade 33 are adjusted. In other words, the distance from the position fixed to the blade fixing member 38, which is the fulcrum of the toner layer regulating blade 33, by the protrusion 39 to the contact position P with the developing roller does not change. In general, the pressing force of the toner layer regulating blade 33 is determined by the amount of deflection of the toner layer regulating blade 33 and the distance from the protrusion 39 to the contact point with the developing roller 31. Therefore, according to this embodiment, the toner layer The pressing force of the toner layer regulating blade 33 does not change before and after the angle adjustment of the regulating blade 33. Further, since the protrusion 39 moves so as to draw an arc centering on the rotation axis of the developing roller 31, the direction in which the pressing force of the toner layer regulating blade 33 is applied does not change with respect to the rotation axis of the developing roller 31. As a result, problems such as a change in the toner layer adhesion amount, white streaks, and toner slipping due to the change in the position of the toner layer regulating blade 33 do not occur.

  In the initial stage of supplying the toner to the photosensitive drum 11, the toner layer regulating blade 33 is fixed at the position shown in FIG. 3A to form a desired charge amount and adhesion amount. However, the developer that has not been used for development is collected in the developing device, passes through the toner layer regulating blade 33 and the developing roller 31 many times, and the surface of the toner is caused by the load of the toner layer regulating blade 33 being pressed. A phenomenon occurs in which the external additive attached to the toner is buried in the developer or the external additive is peeled off from the developer surface. As a result, there arises a problem that the charge amount of the developer decreases with time. A decrease in the charge amount of the toner layer leads to background stains, developer scattering, and the like, and causes image defects.

  In order to improve the problem, it is described in FIGS. 3A and 3B by changing the position of the toner layer regulating blade 33 using the blade angle adjusting mechanism 50 as shown in FIG. As shown in the shaded area, the space above the developing roller 31 is widened on the upstream side of the toner layer regulating blade 33 to increase the toner accumulation amount. When the amount of toner is large, the toners are pressed against each other, the number of contact between the toner and the developing roller 31 is increased, and the charge amount can be increased. Further, since the magnitude of the pressing force of the toner layer regulating blade 33 does not change even after the angle is adjusted, a desired adhesion amount can be obtained. As a result, it is possible not only to improve image defects conventionally caused by a decrease in the charge amount of the toner layer, but also to form a desired image over a longer period of time, and to use toner more efficiently. Become.

  The position of the toner layer regulating blade 33 detects the charge amount of the toner layer formed on the downstream side of the toner layer regulating blade 33, the number of rotations of the developing roller 31, the number of recording sheets 19 on which an image is formed, and the like. Thus, the angle may be changed according to the use situation. Furthermore, if the position of the toner layer regulating blade 33 is changed in a plurality of stages, a desired charge amount of the toner layer can be obtained more stably.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, The range of this invention is shown by a claim, and the meaning and range equivalent to a claim All changes within are intended to be included.

DESCRIPTION OF SYMBOLS 11 Photosensitive drum 12 Charging apparatus 13 Exposure apparatus 14 Developing apparatus 15 Transfer apparatus 16 Cleaning apparatus 17 Static elimination apparatus 18 Fixing apparatus 19 Recording paper 20 Cleaning blade 21 Recovery casing 30 Developer tank 31 Developing roller 32 Toner supply roller 33 Toner layer regulation Blade 34 Toner stirring roller 35 Toner transport roller 36 Leakage prevention sheet 37 Urethane rubber 38 Blade fixing member 39 Projection 40 Angle adjustment hole 50 Blade angle adjustment mechanism

Claims (5)

In a developing device including a developer tank, a developer carrier for supplying developer to the developer carrier, and a developer regulating member.
The developer regulating member includes an elastic body at one end in contact with the developer carrying member, and a developer regulating member angle adjusting mechanism capable of adjusting an angle of the developer regulating member with respect to the horizontal direction is attached to the other end. ,
Before and after changing the angle of the developer regulating member, the contact position on the developer regulating member in contact with the developer carrying member does not change,
The developing device, wherein a direction in which the pressing force of the developer regulating member is applied does not change with respect to a rotation axis of the developer carrying member. The developer regulating member angle adjusting mechanism includes a protrusion and an angle adjusting hole.
The protrusion is fixed to the developer regulating member,
The developing device according to claim 1, wherein the angle adjusting hole is provided in the developer tank so as to draw an arc centering on a rotation axis of the developer carrying member.   The developer regulating member changes the angle in a plurality of stages according to the charge amount of the developer layer, the number of rotations of the developer carrier, or the number of recording sheets on which an image is formed. The developing device according to claim 1.   The developing device according to claim 1, wherein a surface portion of the elastic body of the developer regulating member is in contact with the developer carrier.   An image forming apparatus comprising the developing device according to claim 1.