JP2011102956A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of quickly and appropriately opening and closing a movable shutter, even when an image forming operation is performed after non operation and neglect of the image forming apparatus for a long period of time, and to provide a process cartridge and an image forming apparatus each including the developing device. <P>SOLUTION: The movable shutter 58 configured to open/close the opening 50a of the developing device 5Y is disposed, and a movable shutter moving means 59 configured to open/close the movable shutter 58 is mounted. A movable shutter driving means 60 is controlled by a control means 61, and thereby the opening 50a of the developing device 5Y is shielded by the movable shutter 58 when forming an electrostatic latent image on the surface of a photoreceptor 1Y again after the state, in which the electrostatic latent image is not formed on the photoreceptor 1Y, continues for a first predetermined time. Subsequently, after a second predetermined time, the movable shutter driving means 60 is operated by the control means 61, and thereby the movable shutter 58 is moved to open the opening 50a of the developing device 5Y. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device used in an image forming apparatus such as an electrophotographic copying machine or a printer, a process cartridge including the developing device, and an image forming apparatus.

  Conventionally, in an image forming apparatus, it is detachable to an image forming apparatus that does not require maintenance such as replacement of a consumable part such as a photosensitive member, a developer, or waste toner processing that is difficult for a user to replace. Many process cartridges are used. An existing process cartridge installed in the main body of the image forming apparatus by a user, a serviceman, or the like when the photosensitive member or developer of the process cartridge deteriorates and reaches the end of life as the image forming apparatus operates. And a new process cartridge is newly installed in the apparatus main body.

However, in a color image forming apparatus, it is necessary to keep four types (four colors) of process cartridges that are not compatible for replacement as stock in a new state, and costs and labor related to the management are ignored. It was impossible. Therefore, conventionally, a method has been adopted in which the developing device of the process cartridge at the time before being attached to the image forming apparatus has only a carrier or an empty state and a common process cartridge for each color. However, in such a process cartridge, a much larger amount of toner is supplied when toner is supplied after the image forming apparatus is mounted compared to the amount of toner replenished by normal toner density control. For this reason, the supplied toner cannot be sufficiently mixed with the carrier and is transported with an insufficient amount of charge.
Furthermore, when a two-component developer containing a carrier and toner is supplied after being mounted on the image forming apparatus, the carrier and the toner are sufficiently mixed but may be transported with insufficient frictional charging. . In this way, when the two-component developer that is insufficiently charged is conveyed to the opening facing the photosensitive member of the developing device, the weakly charged toner or the uncharged toner is scattered from the opening, and the image forming apparatus is Contamination problems occur.

In order to solve such problems, a movable shutter that opens and closes the opening of the developing device is provided, and when the toner or the two-component developer is supplied when the process cartridge is replaced, the opening is shielded by the movable shutter, and development is performed in advance. In the apparatus, it is proposed to stir the two-component developer to charge the toner and then move the movable shutter to open the opening to perform the image forming operation to prevent toner scattering (for example, Patent Document 1).
In the invention described in Patent Document 1, the movable shutter is movable by moving the developing device away from the photosensitive member so as to shield the opening only when supplying the toner or developer when the process cartridge is replaced. The shutter is opened and closed.
However, the scattering of the toner from the opening is not limited to the supply of toner or developer at the time of replacing the process cartridge, but is also normal when the image forming operation is performed after leaving the image forming apparatus not operated for a long period of time. This occurs when the toner charge amount during image formation decreases. In such a state, the device described in Patent Document 1 has a problem that the developing device must be moved one by one to open and close the movable shutter, and a quick response cannot be made.

  The present invention has been made in consideration of the above-described circumstances. Even when the image forming operation is operated after the image forming apparatus is left unoperated for a long time, the movable shutter can be opened and closed quickly and appropriately. An object of the present invention is to provide a developing device that can be used, a process cartridge including the developing device, and an image forming apparatus.

  In order to solve the above-mentioned problem, the invention of claim 1 stirs a developer containing portion containing a two-component developer containing toner and a magnetic carrier, and a two-component developer in the developer containing portion, Developer agitating means for charging the toner in the two-component developer, a developer carrier having a rotatable non-magnetic developing sleeve containing a magnetic field generating means, and an image carrier for carrying an electrostatic latent image And an opening for supplying the toner in the two-component developer to the image carrier, and the magnetic field generating means pumps the two-component developer from the developer containing portion. The toner is carried on the surface of the carrier and conveyed to a portion facing the image carrier, and the toner is supplied to the electrostatic latent image on the image carrier by the magnetic brush formed by the magnetic field generating means through the opening. In the developing device When a movable shutter that opens and closes the opening is disposed and the electrostatic latent image is not formed on the image carrier for a first predetermined time and then the electrostatic latent image is formed on the image carrier. In addition, the opening is shielded by the movable shutter, the developer agitating means and the developing sleeve are operated to charge the toner for a second predetermined time, and then the movable shutter is moved to open the opening. The movable shutter moving means is controlled to move the movable shutter so as to open and supply toner to the electrostatic latent image on the image carrier.

According to a second aspect of the present invention, in the developing device according to the first aspect, when the movable shutter shields the opening of the developer carrier, the surface of the movable shutter and the surface of the developing sleeve that faces the movable shutter The movable shutter is arranged such that the interval (L) is L (mm) <M (mm) with respect to the length (M) of the magnetic brush.
According to a third aspect of the present invention, there is provided the developing device according to the first or second aspect, wherein the surface of the movable shutter that comes into contact with the two-component developer carried on the developing sleeve has an average interval of unevenness on the surface ( Sm) is formed to have a concavo-convex surface so that Sm <Dv with respect to the weight average particle diameter (Dv) of the toner in the developer containing portion, and the number of fine powder content of the toner in the two-component developer Is controlled to be 20% or less.
According to a fourth aspect of the present invention, in the developing device according to any one of the first to third aspects, a surface of the movable shutter that contacts the two-component developer carried on the developing sleeve is formed on the two-component developer. It is characterized in that it is coated with a film containing a charge control agent having the same polarity as the charge polarity of the toner in the developer.

According to a fifth aspect of the present invention, in the developing device according to any one of the first to third aspects, a conductive layer is provided on a surface of the movable shutter that contacts the two-component developer carried on the developing sleeve. And a DC bias having the same polarity as the charging polarity of the toner in the two-component developer is applied to the conductive layer.
According to a sixth aspect of the present invention, in the developing device according to the fifth aspect, an AC bias is applied to the conductive layer by superimposing an AC bias on a DC bias having the same polarity as the charging polarity of the toner.
The invention according to claim 7 is the developing device according to any one of claims 1 to 6, wherein the surface of the movable shutter is brought into contact with the surface of the movable member when the movable shutter is moved. The developing device is provided with a cleaning means for removing the toner adhering to the toner.
Further, the invention of claim 8 is the developing device according to claim 7, wherein the cleaning means has a roller shape supported by an axial center, and cleans the movable shutter as the movable shutter moves. Features a developing device.

The invention according to claim 9 is the developing apparatus according to claim 7 or 8, wherein at least a surface of the cleaning unit that contacts the movable shutter is made of an elastic material having a Young's modulus of 5000 Mpa or less. And
According to a tenth aspect of the present invention, there is provided the developing device according to the seventh or eighth aspect, wherein at least a surface of the cleaning unit that contacts the movable shutter is formed of a melamine resin foam.
According to an eleventh aspect of the present invention, there is provided the developing device according to any one of the seventh to tenth aspects, wherein the developing device includes a suction mechanism that sucks toner adhering to the cleaning unit in the vicinity of the cleaning unit. Features.
According to a twelfth aspect of the present invention, there is provided an image carrier on which an electrostatic latent image is formed on a surface, and a developing device that supplies toner to the electrostatic latent image formed on the image carrier and develops the image carrier. 12. The process cartridge connected to at least one body, wherein the developing device is a process cartridge which is the developing device according to any one of claims 1 to 11.
According to a thirteenth aspect of the present invention, there is provided an image carrier on which an electrostatic latent image is formed on a surface, and a developing device that supplies toner to the electrostatic latent image formed on the image carrier and develops the image carrier. In the image forming apparatus provided, the developing device is the developing device according to any one of claims 1 to 11, and is characterized by the image forming device.

  According to the present invention, a movable shutter that opens and closes the opening is disposed, and after the state where no electrostatic latent image is formed on the image carrier for a first predetermined time continues, the electrostatic latent image is applied to the image carrier. When the image is formed, the opening is shielded by the movable shutter, the developer agitating means and the developing sleeve are operated to charge the toner for a second predetermined time, and then the movable shutter is moved. The movable shutter moving means for moving the movable shutter is controlled by the control means so as to move and open the opening to supply toner to the electrostatic latent image on the image carrier, thereby forming an image. A developing device capable of opening and closing a movable shutter quickly and appropriately even when an image forming operation is activated after the device has been left unoperated for a long period of time, and a process car including the developing device It is possible to provide a ridge and an image forming apparatus.

1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. It is a figure which shows schematic structure of the state by which the movable shutter of the developing device which concerns on 1st Embodiment by this invention fell and opening was open | released. It is a figure which shows schematic structure of the state by which the movable shutter of the developing device which concerns on 1st Embodiment by this invention rose and the opening was shielded. FIG. 6 is a graph showing a relationship of toner charge amount (Q / M) when an image forming pre-processing operation is performed. FIG. 7 is a graph showing the result of monitoring the amount of toner scattered from the start of image formation with a dust track. It is a schematic block diagram for demonstrating the arrangement position of the shutter in the developing device which concerns on 2nd Embodiment by this invention. It is a figure which shows the change state of a toner charge amount with a bar graph by the relationship between the length of a magnetic brush and a movable shutter position when an opening is shielded by a movable shutter. It is a figure which shows the uneven | corrugated state of the surface of the movable shutter of the developing device which concerns on 3rd Embodiment by this invention with a graph. FIG. 5 is a graph showing the relationship between the number of toner fine powder content and the toner contamination on the surface of the movable shutter that has been subjected to the image pre-processing operation for a second predetermined time. The relationship between the surface of the movable shutter covered with a coating containing a charge control agent and the toner contamination on the surface of the movable shutter that has undergone the pre-image processing operation for a second predetermined time when the coating is not formed is shown in a graph. FIG. It is a figure which shows schematic structure of the developing device which concerns on 5th Embodiment by this invention. FIG. 6 is a graph showing a relationship between a toner charge amount when a DC bias voltage is applied to a movable shutter and when a DC bias voltage is not applied. It is a figure which shows schematic structure of the developing device which concerns on 6th Embodiment by this invention. FIG. 6 is a graph showing a relationship between toner charge amounts when an AC bias voltage is applied to a movable shutter, when a DC bias voltage is applied, and when a bias voltage is not applied. It is a figure which shows the 1st example of the developing device provided with the cleaning member which cleans a movable shutter. It is a figure which shows the 1st example of the developing device provided with the cleaning member which cleans a movable shutter. It is a figure which shows the relationship between the Young's modulus of the cleaning part material, and the cleaning rate of the movable shutter surface. It is a figure which compares and shows the cleaning rate at the time of making the material of a cleaning part into epichlorohydrin rubber, and making it into a melamine resin foam. It is a figure which shows the 2nd example of the image development apparatus provided with the cleaning member which cleans a movable shutter. FIG. 17 is a diagram comparing the number of movements of the movable shutter until the cleaning portion of the cleaning member shown in FIGS. 15 and 16 and the cleaning portion of the cleaning member shown in FIG. 19 fail. It is a figure which shows the 3rd example of the image development apparatus provided with the cleaning member which cleans a movable shutter. It is the figure which looked at the cleaning member and the suction mechanism from the longitudinal direction. It is a figure which compares and shows the relationship between the frequency | count of a movement of a movable shutter, and a cleaning rate when not providing a suction mechanism.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, an electrophotographic printer (hereinafter simply referred to as a printer) will be described as an example of an embodiment of an image forming apparatus to which the present invention is applied. First, the basic configuration of the printer will be described.
FIG. 1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. In FIG. 1, the printer 100 includes four process cartridges 6Y, 6M, 6C, and 6K for generating toner images of yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and K). ing. These use different colors of Y, M, C, and K toners as image forming substances, but otherwise have the same configuration and are replaced when the lifetime is reached. Taking a process cartridge 6Y for generating a Y toner image as an example, as shown in FIG. 2, a drum cleaning device 2Y (see FIG. 1), a charge eliminating device (not shown), A charging device 4Y (see FIG. 1), a developing device 5Y, and the like are integrally assembled with the photoreceptor 1Y.
The process cartridge 6Y can be attached to and detached from the main body of the printer 100, and the consumable parts can be replaced at once by extracting the process cartridge 6Y from the printer 100. Therefore, the work of the service person or the user at the time of parts replacement can be reduced, and serviceability and usability can be improved.
In the process cartridge 6Y, as shown in the above embodiment, the drum cleaning device 2Y, the static eliminator (not shown), the charging device 4Y, and the developing device 5Y do not have to be integrated with the photoreceptor 1Y. The photosensitive member 1Y and the developing device 5Y or other devices such as the photosensitive member 1Y, the developing device 5Y, and the charging device 4Y may be integrated.

In the printer 100, the process cartridges 6Y, 6M, 6C, and 6K and the toner bottles 32Y, 32M, 32C, and 32K are configured to be separately detachable from the main body of the printer 100. 6M, 6C, 6K and toner bottles 32Y, 32M, 32C, 32K can be separately replaced independently, and toner bottles 32Y, 32M, 32C, 32K can be easily replaced.
As shown in FIG. 1, the charging device 4Y uniformly charges the surface of the photoreceptor 1Y that is rotated clockwise in the drawing by a driving unit (not shown). The surface of the uniformly charged photoreceptor 1Y is exposed and scanned by a laser beam LY emitted from an exposure device 7 (see FIG. 1) to form and carry an electrostatic latent image for Y. The electrostatic latent image of Y is developed into a Y toner image by a developing device 5Y using Y toner, as will be described later. Then, the Y toner image is intermediately transferred onto an endless intermediate transfer belt 8 that is transported in the direction of arrow A. The drum cleaning device 2Y removes the toner remaining on the surface of the photoreceptor 1Y after the intermediate transfer process. Further, the static eliminator neutralizes residual charges on the photoreceptor 1Y after cleaning. By this charge removal, the surface of the photoreceptor 1Y is initialized and prepared for the next image formation. In the other process cartridges 6M, 6C, and 6K, M, C, and K toner images are similarly formed on the photoreceptors 1M, 1C, and 1K, and are intermediately transferred onto the intermediate transfer belt 8.

In FIG. 1 shown above, an exposure device 7 is disposed below the process cartridges 6Y, 6M, 6C, 6K in the drawing. The exposure device 7 serving as a latent image forming unit emits the laser beams LY, LM, LC, and LK corresponding to the respective color images emitted based on the image information to the respective photoreceptors 1Y in the process cartridges 6Y, 6M, 6C, and 6K. 1M, 1C, and 1K are irradiated to form electrostatic latent images corresponding to the respective color images. The exposure device 7 irradiates the photosensitive member through a plurality of optical lenses and mirrors while scanning the laser beams LY, LM, LC, and LK emitted from the light source with a polygon mirror that is rotationally driven by a motor. is there.
As shown in FIG. 1, a sheet feeding unit having a sheet storage cassette 26, a sheet feeding roller 27 incorporated therein, a registration roller pair 28, and the like is disposed on the lower side of the exposure apparatus 7 in the drawing. The paper storage cassette 26 stores a plurality of transfer papers P as recording media, and a paper feed roller 27 is in contact with the uppermost transfer paper P. When the paper feeding roller 27 is rotated counterclockwise in the drawing by a driving means (not shown), the uppermost transfer paper P is fed toward the rollers of the registration roller pair 28. The registration roller pair 28 rotationally drives both rollers to sandwich the transfer paper P, but temporarily stops rotating immediately after sandwiching. Then, the transfer paper P is sent out toward a secondary transfer nip described later at an appropriate timing. In the sheet feeding unit having such a configuration, a conveying unit is configured by a combination of the sheet feeding roller 27 and the registration roller pair 28 corresponding to the timing roller. This transport means transports the transfer paper P from a paper storage cassette 26 serving as a storage means to a secondary transfer nip described later.

Above the process cartridges 6Y, 6M, 6C, and 6K in the drawing, an intermediate transfer unit 15 that moves the endless intermediate transfer belt 8 that is an intermediate transfer body while stretching is disposed. In addition to the intermediate transfer belt 8, the intermediate transfer unit 15 includes four primary transfer bias rollers 9Y, 9M, 9C, and 9K, a cleaning device 10, and the like. A secondary transfer backup roller 12, a cleaning backup roller 13, a tension roller 14 and the like are also provided. The intermediate transfer belt 8 is endlessly moved counterclockwise (in the direction of arrow A) in the drawing by being driven by rotation of at least one of the rollers while being stretched around these three rollers. The primary transfer bias rollers 9Y, 9M, 9C, and 9K sandwich the intermediate transfer belt 8 that is moved endlessly in this manner from the photoreceptors 1Y, 1M, 1C, and 1K to form primary transfer nips, respectively. Yes.
In these methods, a transfer bias having a polarity opposite to that of toner (for example, plus) is applied to the back surface (loop inner peripheral surface) of the intermediate transfer belt 8. All the rollers except the primary transfer bias rollers 9Y, 9M, 9C, and 9K are electrically grounded. The intermediate transfer belt 8 sequentially passes through the primary transfer nips for Y, M, C, and K along with the endless movement thereof, and Y, M, and C on the photoreceptors 1Y, 1M, 1C, and 1K. , K toner images are superimposed and primarily transferred. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the intermediate transfer belt 8.

The secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 between the secondary transfer roller 19 and forms a secondary transfer nip. The four-color toner image formed on the intermediate transfer belt 8 is transferred to the transfer paper P at the secondary transfer nip. Untransferred toner that has not been transferred onto the transfer paper P adheres to the intermediate transfer belt 8 after passing through the secondary transfer nip. This is cleaned by the cleaning device 10.
In the secondary transfer nip, the transfer paper P is sandwiched between the intermediate transfer belt 8 and the secondary transfer roller 19 whose surfaces move in the forward direction, and conveyed in the opposite direction to the registration roller pair 28 side. The When the transfer paper P sent out from the secondary transfer nip passes between the rollers 20a and 20b of the fixing device 20, the four-color toner image transferred to the surface is fixed by heat and pressure. Thereafter, the transfer paper P is discharged out of the apparatus through a pair of paper discharge rollers 29. A stack unit 30 is formed on the upper surface of the printer body, and the transfer paper P discharged outside the apparatus by the discharge roller pair 29 is sequentially stacked on the stack unit 30.

  The configuration of the developing device 5Y in the process cartridge 6Y will be described with reference to FIG. The developing device 5Y has a magnetic field generating means therein, and a developing roller 49, which is a developer carrying member having a non-magnetic developing sleeve 51 that carries and rotates a two-component developer containing magnetic carrier particles and toner on the surface. And a doctor 52 as a developer regulating member that regulates the layer thickness of the developer carried and conveyed on the developing sleeve 51. A developer accommodating portion 53 that accommodates the developer regulated by the doctor 52 without being conveyed to the developing area facing the photoreceptor 1Y is formed on the upstream side of the doctor 52 in the developer conveying direction. Further, adjacent to the developer accommodating portion 53, a toner accommodating portion 54 for accommodating toner and toner conveying screws 55A and 55B for agitating and conveying the toner are provided. The developing sleeve 51 and the toner conveying screws 55A and 55B are rotatably mounted in the developing housing 50. In the developing housing 50, a doctor 52, a developer containing portion 53, a toner containing portion 54, and the like. Is formed. In FIG. 2, reference numeral 56 denotes a toner supply port.

Next, the operation of the developing device 5Y will be described. In the developing device 5Y, a developer layer is formed on the developing sleeve 51 by the magnetic field generating means of the developing roller 49. Further, the toner is taken into the developer from the developer accommodating portion 53 by the movement of the developer layer conveyed by the rotation of the developing sleeve 51. The toner is taken in while the toner density is detected by the toner density detecting means 48Y so that the developer is within a predetermined toner density range and controlled based on the detected toner density. The toner taken into the developer is charged by stirring with the toner conveying screws 55A and 55B and frictional charging with the carrier between the developing sleeve 51 and the doctor 52. The developer containing charged toner is supplied to the surface of the developing sleeve 51 having a magnetic field generating means inside the developing roller 49 and is carried by the magnetic force of the magnetic field generating means.
The developer layer carried on the developing sleeve 51 is conveyed in the direction of arrow B as the developing sleeve 51 rotates. On the way, after the thickness of the developer layer is regulated by the doctor 52, the developer layer is conveyed to the opening 50a which becomes a developing region facing the photoreceptor 1Y. In the development area, the electrostatic latent image formed on the photoconductor 1Y is supplied with toner from a developer developing brush formed by the magnetic field generating means, and the electrostatic latent image is converted into a toner image for development. Is called. The developer layer remaining on the developing sleeve 51 is conveyed to the upstream portion of the developer accommodating portion 53 in the developer conveying direction as the developing sleeve 51 rotates.

In this case, when the developer has not been used for a long time or is left in a high temperature and high humidity environment, the toner and the carrier are not triboelectrically charged or hardly triboelectrically charged. Decreases. As described above, when the image forming operation is started in a state where the charge amount of the toner is reduced, the electrostatic adhesion force between the toner and the carrier is weakened. By scattering from the opening 50a into the machine, there are problems such as abnormal images such as in-machine dirt and toner dropping, and in some cases, the scattered toner comes out of the machine and becomes dust, which adversely affects the human body. In particular, at the start of the image forming operation, the charging of the toner is often reduced, and a lot of toner scattering occurs.
Therefore, in the present invention, after a state where no electrostatic latent image is formed on the photoreceptor 1Y for a first predetermined time or longer, such as when it has not been used for a long time or when it is left in a high temperature and high humidity environment, Again, when an electrostatic latent image is formed on the surface of the photoreceptor 1Y, the opening 50a of the developing device 5Y is shielded by the movable shutter 58, the developer is sealed in the developing device 5Y, and the toner is out of the developing device 5Y. To avoid splashing. Then, the toner conveying screws 55A and 55B and the developing sleeve 51 are rotationally driven for a second predetermined time to rub the toner and the carrier, or the developer is rubbed by the doctor 52 and the toner conveying screws 55A and 55B. Therefore, the charging of the toner is started to ensure the electrostatic adhesion between the toner and the carrier.

By performing these two operations before image formation, it is possible to prevent problems due to toner scattering during image formation (particularly at the start of the image formation operation). In this case, in order to perform such an operation quickly and reliably, the developing device 5Y according to the first embodiment of the present invention has an opening 50a of the developing device 5Y as shown in FIGS. A movable shutter 58 that opens and closes is provided, and a movable shutter moving means 59 that opens and closes the movable shutter 58 is attached. The movable shutter moving means 59 has a movable shutter driving means 60 for moving the movable shutter 58 in the directions of arrows C1 and C2. Then, the movable shutter driving means 60 is controlled by the control means 61, and after the state where no electrostatic latent image is formed on the photoreceptor 1Y for a first predetermined time (for example, 72 hours) continues, the photoreceptor 1Y again. When the electrostatic latent image is formed on the surface, the opening 50a of the developing device 5Y is shielded by the movable shutter 58. Subsequently, after the opening 50a is shielded by the movable shutter 58, after a second predetermined time (for example, 5 minutes), the movable shutter driving means 60 is operated by the control means 61 to move the movable shutter 58, and the developing device 5Y is moved. The opening 50a is opened. Note that the numerical values of the first predetermined time and the second predetermined time are examples, and various numerical values can be adopted in consideration of the developing system and the charge amount of the toner.
That is, as shown in FIG. 2, the input means 62 detects that an electrostatic latent image is not formed on the photoconductor 1Y for a first predetermined time, and again the surface of the photoconductor 1Y. When an operation for forming an electrostatic latent image is detected, an input signal is supplied to the control means 61 to drive the movable shutter drive means 60. As a result, by driving the movable shutter driving means 60, the movable shutter moving means 59 is actuated to raise the movable shutter 58 in the C1 direction and shield the opening 50a of the developing device 5Y. In this case, the movable shutter 58 is made of a 0.05 mm-thick plastic or metal plate, and the movable shutter 58 is moved in the C1 direction by the movable shutter moving means 59 by operating the movable shutter driving means 60. The opening 50a of the developing device 5Y is shielded by the movable shutter 58, and the developer can be sealed in the developing device 5Y. The thickness of the movable shutter is merely an example, and various thicknesses can be used in consideration of the developing system and the charge amount of the toner.

As the movable shutter moving means 59, for example, the cam surface of the cam mechanism is brought into contact with the bottom surface portion 58a of the movable shutter 58, and the movable shutter 58 is moved up and down by rotating the drive motor that becomes the movable shutter driving means 60. It can be movable. Alternatively, the movable shutter 58 may be moved up and down by rotating the pinion gear using a rack gear that holds the side surface of the movable shutter 58 and a pinion gear that meshes with the rack gear to move the rack gear up and down.
In this embodiment, in order to improve the sealing performance of the opening 50 a of the developing device 5 </ b> Y by the movable shutter 58, a seal portion 57 that suppresses toner scattering is connected to the doctor 52.
In this manner, with the opening 50a of the developing device 5Y shielded by the movable shutter 58, the toner conveying screws 55A and 55B and the developing sleeve 51 are rotationally driven for a second predetermined time as shown in FIG. Then, the toner and the carrier are rubbed, or the developer is rubbed up by the doctor 52, the toner conveying screws 55A and 55B, etc., and the charging of the toner is started. Thereafter, when the second predetermined time and the rotation stop of the toner conveying screws 55A and 55B and the developing sleeve 51 are detected, a signal for lowering the movable shutter is sent from the input means 62 to the control means 61 to drive the movable shutter. By driving the means 60, the movable shutter 58 is lowered in the direction of arrow C2 (see FIG. 3), the opening 50a of the developing device 5Y is opened, toner can be supplied to the photoreceptor 1Y, and normal image formation (image formation) is performed. Operation starts.

The amount of toner charge (Q / M) and the amount of scattered toner were measured with and without the toner charging process (hereinafter referred to as pre-image forming process) accompanying the opening and closing operation of the shutter. The results are shown in FIGS.
FIG. 4 shows a case where the above-mentioned image pre-processing operation was performed after leaving the developer for 72 hours in an environment of 27 ° C. and 80% RH (bar graph 1), and the image pre-processing operation was not performed. It is a measurement result of toner charge amount (Q / M) in the case (bar graph 2).
FIG. 5 shows the result of monitoring the amount of toner scattering from the start of image formation using a dust track.
From the result of FIG. 4, the toner charge amount is twice or more higher when the pre-image processing operation is performed (bar graph 1) than when the pre-image processing operation is not performed (bar graph 2). it is obvious.
From the results of FIG. 5, it can be seen that the amount of toner scattering is significantly reduced in the pre-processing operation ant (curve 3) compared to the pre-processing operation pear (curve 4).

Next, a developing device according to a second embodiment of the present invention will be described with reference to FIGS.
FIG. 6 is a schematic configuration diagram for explaining the position of the shutter in the developing device according to the second embodiment of the present invention.
FIG. 7 is a bar graph showing a change state of the toner charge amount in relation to the length of the magnetic brush and the position of the movable shutter when the opening is shielded by the movable shutter.
In the second embodiment, in the developing device 5Y according to the first embodiment, the arrangement position of the movable shutter 58 is changed variously, the change state of the toner charge amount is examined, and the optimum arrangement position of the movable shutter 58 is examined. It was investigated. As a result, as shown in FIG. 6, the position of the movable shutter 58 is set such that the distance between the surface 58b and the developing sleeve 51 on the movable shutter 58 is L, and the length M of the magnetic brush J formed on the developing sleeve 51 is. On the other hand, if L (mm) <M (mm), the toner charge amount increases when the movable shutter 58 shields the opening 50a and frictionally charges the toner.
That is, when the magnetic brush J formed on the developing sleeve 51 is in contact with the surface 58b of the movable shutter 58 (contact), and when the magnetic brush J is not in contact with the surface 58b of the movable shutter 58 (non-contact). ), The toner charge amount was measured after the pre-image processing operation and before the pre-operation processing operation with the second predetermined time as the same time.

FIG. 7 shows the results. The bar graph 5 shows the toner charge amount after the pre-image processing operation is performed in the contact state, and the bar graph 6 shows the toner charge before the image pre-processing operation is performed in the contact state. The bar graph 7 shows the toner charge amount after the pre-image forming processing operation is performed in the non-contact state, and the bar graph 8 shows the toner charge amount before the image pre-processing operation is performed in the non-contact state. Yes. As is apparent from this result, when the pre-image forming processing operation is performed, the movable shutter 58 is formed on the developing sleeve 51 with a distance L between the surface 58b and the developing sleeve 51 as the arrangement position of the movable shutter 58. It can be seen that if L (mm) <M (mm) with respect to the length M of the magnetic brush J, the toner charge amount increases and the toner charge rises quickly.
In order to achieve such a relationship of L <M, L may be reduced by narrowing the interval (development gap) between the photoreceptor 1Y and the developing sleeve 51 in accordance with the system of the image forming apparatus to be implemented. By increasing the distance between the doctor 52 and the developing sleeve 51 (doctor gap), the amount of developer pumped up may be increased, and the length M of the magnetic brush J may be increased. With such L <M, the magnetic brush J and the movable shutter 58 come into contact with each other during the pre-image forming processing operation, and the magnetic brush J slides on the surface of the movable shutter 58 and the developer is squeezed. As a result, the charging efficiency of the toner increases. Incidentally, in the second embodiment, the movable shutter 58 is set at a position where the length M of the magnetic brush J is about 0.6 mm and the distance L is about 0.3 mm. It should be noted that the above values of M and L in this embodiment are merely examples, and it goes without saying that various values can be adopted in consideration of the development system and the charge amount of the toner.

Next, a third embodiment according to the present invention will be described.
In the first embodiment described above, when toner contamination is promoted on the surface 58b of the movable shutter 58, the toner particles enter and adhere to the inlet and the inside of the movable shutter 58 of the movable shutter moving means 59, and the movable shutter moving means. 59 such as a failure occurs. Therefore, in the pre-image forming operation, the toner is made smaller than the weight average particle diameter (Dv) of the toner particles using the average interval (Sm) of the unevenness of the surface 58b of the movable shutter 58 that contacts the magnetic brush J. By preventing the particles from adhering to the surface 58 b of the movable shutter 58, the toner particles are prevented from entering the movable shutter moving means 59. The toner particles generally have a weight average particle diameter (Dv) of 1 μm to 50 μm, and the surface 58b of the movable shutter 58 is taken into consideration in consideration of the weight average particle diameter (Dv) of the toner particles. What is necessary is just to set the average space | interval (Sm) of the unevenness | corrugation of this so that it may become Sm <Dv suitably.

この場合、Ｓｍは機械の送り量に対応することが多く、Ｓｍが小さいと加工の目が細かいと判断される。 Below, the outline | summary of an uneven | corrugated average space | interval (Sm) and the measuring method of a weight average particle diameter (Dv) are demonstrated.
[Average unevenness (Sm)]
The roughness of the surface 58b of the movable shutter 58 is measured to obtain a roughness curve as shown in FIG. From this roughness curve, only the reference length D is extracted in the direction of the average line, and the length corresponding to one peak (Sm1) and one valley (Sm2) adjacent thereto is measured, and these lengths Sm1 to Sm1 are measured. The average length Sm (millimeter) of Smn was calculated from the following equation (Equation 1).
(Equation 1)

In this case, Sm often corresponds to the feed amount of the machine, and if Sm is small, it is judged that the eyes of processing are fine.

[Weight average particle diameter (Dv)]
The weight average particle diameter (Dv) and the number average particle diameter (Dn) of the toner particles are measured by a Coulter counter method. Examples of the measuring device for the particle size distribution of toner particles include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter).
First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of an aqueous electrolytic solution. Here, the electrolytic solution is a solution prepared by preparing a 1% NaCl aqueous solution using primary sodium chloride. For example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the weight and number of toner particles or toner are measured and measured by the measuring device using a 100 μm aperture as the aperture. Calculate distribution and number distribution. From the obtained distribution, the weight average particle diameter (Dv) and the number average particle diameter (Dn) of the toner can be obtained. As channels, 2.00 to less than 2.52 μm; 2.52 to less than 3.17 μm; 3.17 to less than 4.00 μm; 4.00 to less than 5.04 μm; 5.04 to less than 6.35 μm; 6 Less than 35 to 8.00 μm; less than 8.00 to less than 10.08 μm; less than 10.08 to less than 12.70 μm; less than 12.70 to less than 16.00 μm; less than 16.00 to less than 20.20 μm; Uses 13 channels of less than 40 μm; 25.40 to less than 32.00 μm; 32.00 to less than 40.30 μm, and targets particles having a particle size of 2.00 μm to less than 40.30 μm.
By making the unevenness average interval (Sm) of the surface 58b where the magnetic brush J and the movable shutter 58 come into contact smaller than the weight average particle diameter (Dv) of the toner to be used, the toner particles physically come into contact with the surface 58b of the movable shutter 58. It becomes difficult to enter the uneven portion of the toner, and toner contamination on the surface 58b of the movable shutter 58 can be reduced. However, since the unevenness of the surface 58b of the movable shutter 58 and the toner particle size vary, the toner contamination of the movable shutter 58 cannot be completely eliminated simply by defining the unevenness and the toner particle size. In particular, the fine powder component of the toner having a diameter smaller than the uneven average interval (Sm) easily enters the uneven portion of the surface 58b of the movable shutter 58 and contaminates the movable shutter surface. Therefore, in the present invention, it has been considered to define the amount of toner in the developer.

FIG. 9 is a graph showing the relationship between the toner fine powder content and the toner contamination on the surface of the movable shutter that has been subjected to the pre-image forming operation for a second predetermined time. In FIG. 9, ID was measured by an X-Rite toner density detector as the density when the toner stain on the surface of the movable shutter was transferred to the tape. A higher ID value indicates more toner contamination.
From the results of FIG. 9, as the number fine powder content of the toner increases, the ID increases and the toner contamination increases, but when the toner fine powder content exceeds 20%, the ID suddenly increases. it is obvious. From this result, the toner contamination of the movable shutter is greatly improved to a level where there is no problem by using the toner whose toner fine particle content is defined as 20% or less.

Next, 4th Embodiment by this invention is described based on FIG. FIG. 10 shows the relationship between the surface of the movable shutter that has been coated with a coating containing a charge control agent and the toner contamination on the surface of the movable shutter that has undergone the pre-image processing operation for a second predetermined time when the coating is not formed. FIG.
In the third embodiment described above, the toner contamination of the movable shutter is reduced by defining the toner fine powder content rate to 20% or less. However, this method has problems that the manufacturing process of the movable shutter and the toner classification process are complicated and the manufacturing cost is increased.
Therefore, in the present embodiment, the surface 58b of the movable shutter 58 is covered with a coating containing a charge control agent having the same polarity as that of the toner to prevent the toner from adhering to the surface 58b of the movable shutter 58. Thus, the toner contamination of the movable shutter 58 is reduced. If the polarity of the surface 58b of the movable shutter 58 is the same as that of the toner, a repulsive force acts between the toner and the surface 58b of the movable shutter 58, and the toner hardly adheres to the movable shutter 58. Dirt can be reduced.

一般式（１）

In FIG. 10, the toner stains on the surface of the movable shutter when the surface 58b of the movable shutter 58 is coated with a coating containing a charge control agent having the same polarity as that of the toner (with coating) and without coating are transferred to the tape. The ID value measured by X-Rite is shown as the density at the time. In FIG. 10, the bar graph 10 indicates a case with a coat, and the bar graph 11 indicates a case without a coat. From this result, it is clear that when the coat is formed, the toner contamination is reduced to half or less as compared with the case where the coat is not formed.
The coating film containing the charge control agent can be easily formed by applying a coating solution obtained by dissolving the charge control agent in a solvent together with the binder to the surface 58b of the movable shutter 58. In this case, when the toner is positively charged, the movable shutter surface 58b has a nigrosine dye having the following structural formula (1) or a quaternary ammonium salt having the following general formula 1 as a positively charged charge control agent. Etc. can be used. In the following general formula (1), R1 to R4 are alkyl groups, and X is an anion component such as halogen.
Structural formula (1)

General formula (1)

なお、上記一般式（２）中、Ｍは、Ｃｒ及びＦｅから選択される金属原子、Ｘはハロゲン原子、Ｙは、Ｈ等のカチオン成分である。
一般式（３）

上記一般式（３）中、Ｍは、Ｃｒ、Ｚｎ、Ａｌ、Ｆｅ、ＺｒＯ、Ｂから選択される原子又は化合物である。
構造式（２）

When the toner is negatively charged, the movable shutter surface 58b has, on the movable shutter surface 58b, an azo metal complex represented by the following general formula (2), a salicylic acid metal complex represented by the following general formula (3), and the following structure. Calixarenes of formula (2) can be used. Of course, any substance other than those listed above can be used as long as the charge control agent can provide the same effect.
[General formula (2)]

In the general formula (2), M is a metal atom selected from Cr and Fe, X is a halogen atom, and Y is a cation component such as H.
General formula (3)

In the general formula (3), M is an atom or compound selected from Cr, Zn, Al, Fe, ZrO, and B.
Structural formula (2)

Next, 5th Embodiment by this invention is described based on FIG.11 and FIG.12.
FIG. 11 is a diagram showing a schematic configuration of a developing device according to the fifth embodiment of the present invention. FIG. 12 is a graph showing the relationship between the toner charge amount when the DC bias voltage is applied to the movable shutter and when it is not applied.
In the fifth embodiment, as shown in FIG. 11, the movable shutter 58 is made of a conductive material such as metal, and the conductive layer 58c is formed on the surface 58b of the movable shutter 58. The application time is controlled by the control means 61 by the switch means SW1 so that a bias having the same polarity as the toner is applied to the conductive layer 58c from the DC bias power supply 63. At this time, since the developing roller 49 is grounded, an electric field is generated in the movable shutter 58 and the developing sleeve 51. In this way, by applying a bias having the same polarity as that of the toner, the charge injection into the toner that has passed between the movable shutter 58 and the developing sleeve 51 is used during the pre-image forming processing operation. Charging efficiency can be increased. In the fifth embodiment, the movable shutter 58 is formed of a conductive material such as metal. However, a plate-like plastic is used as the base material, and a conductive layer 58c is formed on the surface thereof by metal plating or the like. It may be a thing.

FIG. 12 shows a case where a direct current bias having the same polarity as that of the toner is applied (bar graph 13) and the image forming operation when the image forming preprocessing operation is performed after leaving the developer for 72 hours in an environment of 27 ° C. and 80% RH. When a DC bias having the same polarity as that of the toner is applied before the image pre-processing operation (bar graph 12), and when performing a pre-image processing operation, the DC bias having the same polarity as that of the toner is not applied (bar graph 15). In addition, the measurement result of the toner charge amount (Q / M) when the DC bias having the same polarity as that of the toner is not applied (bar graph 14) before the image forming preprocessing operation is shown. In this case, the second predetermined time of the image forming preprocessing operation is the same.
From the results of FIG. 12, it is clear that the toner charge amount can be significantly increased when the bias is applied and the charge is injected into the toner than when the bias is not applied.

Next, 6th Embodiment by this invention is described based on FIG.13 and FIG.14.
FIG. 13 is a diagram showing a schematic configuration of a developing device according to the sixth embodiment of the present invention. FIG. 14 is a graph showing the relationship between the toner charge amount when an AC bias voltage is applied to the movable shutter, when a DC bias voltage is applied, and when no bias voltage is applied.
In the sixth embodiment, as shown in FIG. 13, a DC bias power source 63 and an AC power source 64 are connected to a conductive layer 58c of a movable shutter 58 made of a conductive material such as metal to apply a DC bias to the AC. The application means is controlled by the control means 61 by the switch means SW2 so as to apply the superimposed AC bias.
When the AC voltage is superimposed, in addition to the charge injection effect on the toner, the charged particles (carrier and toner) in the developer repeat the oscillating motion, so that the efficiency of triboelectric charging between the toner and the carrier increases.

FIG. 14 shows a case where an AC bias is applied (bar graph 17) and an image pre-processing operation when an image pre-processing operation is performed after leaving the developer for 72 hours in an environment of 27 ° C. and 80% RH. When an AC bias is applied before the image formation (bar graph 16), and when a DC bias having the same polarity as that of the toner is applied during the image formation preprocessing operation (bar graph 19), before the image formation preprocessing operation is performed. When a DC bias having the same polarity as that of the toner is applied (bar graph 18), and when performing the pre-image processing operation, the bias is applied when no bias is applied (bar graph 21) and before performing the pre-image processing operation. The measurement result of the toner charge amount (Q / M) in the case of not performing (bar graph 20) is shown. In this case, the second predetermined time of the image forming preprocessing operation is the same.
From the results shown in FIG. 14, when performing the pre-image processing operation, the toner charge amount is significantly greater when the AC bias is superimposed on the DC bias than when only the DC bias is applied or when no bias is applied. It can be seen that can rise.

By the way, even when the image forming apparatus is not used for a long time (first predetermined time) or is left in a high temperature and high humidity environment, the movable apparatus described in the first to sixth embodiments is used. When the pre-image forming process involving the opening / closing operation of the shutter 58 is executed every time, there are problems such as an increase in the waiting time and power consumption of the user, and an unnecessary deterioration of the developer. Such a problem can be solved by executing the pre-image processing operation only when the charge amount of the toner in the developing device is reduced and the condition for toner scattering at the start of image formation is satisfied.
However, in the case of the configuration of the two-component developing device, the movable shutter 58 and the magnetic brush J are in contact with each other during the pre-image processing operation (moving the movable shutter and stirring), so that the toner is on the developing sleeve 51 side of the movable shutter 58 The problem remains that it adheres to the surface 58b.

As is generally the case, in the image forming apparatus of this embodiment, the temperature around the developing device reaches a high temperature under the following conditions (1) to (3). For example, in the case of the present embodiment, the temperature around the developing device when the conditions (1) to (3) all overlap is about 55 ° C.
(1) When used in a high temperature environment (2) When continuous paper is passed (3) When double-sided paper is passed Adhered toner on the surface 58b of the movable shutter 58 is left in a high temperature environment exceeding 50 ° C for a long time. As a result, the toner wax aggregates or adheres to the surface 58b due to the exudation of the wax component of the toner. This may hinder the movement of the movable shutter 58, cause a malfunction, and may break down in some cases.
Therefore, the surface 58b of the movable shutter 58 is rubbed with a cleaning member when the movable shutter is moved, so that the adhered toner is removed, and toner sticking to the surface 58b and problems associated therewith are prevented.

FIGS. 15 and 16 are views showing a first example of a developing device provided with a cleaning member for cleaning the movable shutter.
FIG. 15 is a diagram showing when the movable shutter is stored, and FIG. 16 is a diagram showing when the movable shutter is moved. 15 and 16, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals, and the description thereof is omitted. The movable shutter driving means 60, the control means 61, and the input means 62 shown in FIGS.
Needless to say, the cleaning member shown in FIGS. 15 and 16 can also be applied to the developing device having the configuration shown in FIGS. 6, 11, and 13.
A first cleaning member (hereinafter simply referred to as a cleaning member) 70 shown in FIGS. 15 and 16 includes a cleaning portion (cleaning means) 70a and a cleaning portion base 70b that supports the cleaning portion 70a.
The cleaning member 70 is provided so that the cleaning unit 70a contacts the surface 58b of the movable shutter 58. When the movable shutter 58 moves, the cleaning unit 70a always contacts the surface 58, and the toner adhered by rubbing is removed. Remove.

With this configuration, the toner adhering to the movable shutter 58 (surface 58b) is not left for a long time in a high-temperature environment, and the movable shutter does not operate properly due to toner adhering to the surface 58b of the movable shutter. It is possible to prevent problems such as failure.
In addition, as the cleaning part 70a of the cleaning member 70, for example, an elastic material having a Young's modulus of 5000 MPa or less is used. By doing so, it is possible to secure a frictional force when the movable shutter surface 58b and the cleaning unit 70a rub against each other when the movable shutter 58 is moved, and to improve the cleaning ability.
On the other hand, when the Young's modulus is 5000 Mpa or more, the frictional force at the time of sliding is hardly obtained, and the cleaning effect of the movable shutter is hardly obtained.

FIG. 17 is a diagram showing the relationship between the Young's modulus of the cleaning part material and the cleaning rate of the movable shutter surface.
In addition, the cleaning rate of the movable shutter surface 58b here shall be represented by the following formula | equation (Equation 2).
(Equation 2)
Cleaning rate [%] = (shielding member (movable shutter) density without cleaning member−shielding member density with cleaning member) / shielding member density without cleaning mechanism However, the shielding member density is a reflection type. A value obtained by actually measuring the surface density of the movable shutter with an optical densitometer is used.
As shown in FIG. 17, it can be seen that when a material having a Young's modulus of 5000 MPa or more is used, a cleaning effect is hardly obtained. This is because when the Young's modulus is 5000 Mpa or more, almost no frictional force can be obtained during rubbing between the cleaning portion 70a and the movable shutter surface 58b.
Therefore, the material of the cleaning part 70a is desirably an elastic material having a Young's modulus of 5000 MPa or less.

Elastic materials having a Young's modulus of 5000 MPa or less include natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene, styrene butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylonitrile butadiene rubber, ethylene-propylene rubber, neopropylene rubber. , Rubber materials such as chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicon rubber, fluorine rubber, urethane rubber, polyethylene elastomer, polyolefin elastomer, 1,2-polybutadiene elastomer, ethylene-vinyl acetate Elastomer, polyvinyl chloride elastomer, natural rubber elastomer, fluororubber elastomer, trans-polyisoprene elastomer, polyethylene chloride Thermoplastic elastomer materials such as steamers, polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polypropylene, polystyrene, polyamide, polyurethane, polycarbonate, polytetrafluoroethylene, acrylonitrile butadiene styrene resin, acrylotolyl butadiene styrene resin, methacrylic resin, etc. And synthetic resin materials.
Moreover, the cleaning capability of the cleaning part 70a can further be improved by making the material of the cleaning part 70a into a melamine resin foam.

FIG. 18 compares the cleaning rate (formula (number (2))) of the movable shutter surface 58b when the material of the cleaning part 70a is epichlorohydrin rubber, which is a typical elastic rubber material, and when it is made of a melamine resin foam. FIG.
As shown in FIG. 18, the cleaning rate can be improved by 1.5 times or more when the cleaning part 70 a is made of a melamine resin foam (bar graph 81) and when it is epichlorohydrin rubber (bar graph 80).
This is because the melamine resin foam has a structure in which a large number of fine holes are formed in the foam, and the adhered toner can be efficiently accumulated in the holes.

FIG. 19 is a diagram illustrating a second example of the developing device provided with a cleaning member for cleaning the movable shutter.
A second cleaning member (hereinafter simply referred to as a cleaning member) 71 shown in FIG. 19 has a roller shape including an axis 71b and a cleaning portion 71a covering the shaft 71b.
The cleaning member 71 is provided so that the cleaning unit (cleaning unit) 71a abuts on the surface 58b of the movable shutter 58. When the movable shutter 58 moves, the cleaning unit 71a always comes in contact with the surface 58. Rotate and rub to remove the adhering toner.
By comprising in this way, the stress concerning the cleaning member 71 at the time of cleaning can be decreased, and the lifetime of a cleaning member can be extended.
In addition, the member which comprises the cleaning part 71a can use the material similar to the cleaning part 70a of the above-mentioned 1st cleaning member 70. FIG.

20 shows the number of movements of the movable shutter 58 until the cleaning portion 70a of the first cleaning member 70 shown in FIGS. 15 and 16 and the cleaning portion 71a of the second cleaning member 71 shown in FIG. 19 fail. FIG.
In addition, both the cleaning parts use the same melamine resin foam.
As shown in FIG. 20, the cleaning portion of the first cleaning member 70 fails in 23 movement operations (bar graph 82), whereas the cleaning portion of the second cleaning member 71 moves 532 times. No bankruptcy occurred (bar graph 83). In this way, with the configuration of FIG. 19, the life of the cleaning unit can be extended about 23 times.
Here, the failure of the cleaning unit is defined as a reduction in the cleaning rate of the surface 58b of the movable shutter by 50% or more.
Furthermore, a suction mechanism is provided in the vicinity of the cleaning member 71, and the toner adhering to the cleaning unit is periodically sucked and removed, thereby preventing the cleaning ability of the cleaning member 71 from being lowered.

FIG. 21 is a view showing a third example of the developing device provided with a cleaning member for cleaning the movable shutter, and a suction mechanism is provided in the vicinity of the roller-like cleaning member 71 shown in the second example.
The suction mechanism 72 shown in FIG. 21 generates an air flow in the direction of the arrow, and periodically sucks and removes toner adhering to the cleaning portion 71a of the cleaning member 71, thereby preventing the cleaning member 71 from being deteriorated in cleaning ability.
FIG. 22 is a view of the cleaning member 71 and the suction mechanism 72 as seen from the longitudinal direction.
The suction mechanism 72 is configured to cover all the longitudinal direction of the cleaning member 71, and can generate an air flow when the cleaning member 71 rotates with the movable shutter 59 to suck and remove the toner in the entire cleaning unit 71 a. .
FIG. 23 is a diagram comparing the relationship between the number of movements of the movable shutter 59 and the cleaning rate of the movable shutter surface 58b (see Expression (2)) when the suction mechanism 72 is not provided and when the suction mechanism 72 is provided. .
In the absence of the suction mechanism, the cleaning rate decreases as the number of movements of the movable shutter 59 increases (curve 85), but in the presence of the suction mechanism, almost no decrease is seen (curve 84).

1Y, 1M, 1C, 1K photoconductor, 2Y cleaning device, 4Y charging device, 5Y,
5M, 5C, 5K development device, 6Y, 6M, 6C, 6K process cartridge, 7 exposure device, 8 intermediate transfer belt, 9Y, 9M, 9C, 9K primary transfer roller, 12 secondary transfer backup roller, 13 cleaning backup roller, 14 tension roller, 15 secondary transfer unit, 19 secondary transfer roller, 20 fixing device, 49 developing roller, 50 developing housing, 50a opening, 51 developing sleeve, 52 doctor, 53 developer container, 54 toner container, 55A , 55B toner conveying screw, 56 toner supply port, 57 seal portion, 58 movable shutter, 58a bottom surface portion, 58b surface, 59 movable shutter moving means, 60 movable shutter drive means, 61 control means, 62 input means, 63 DC bias power supply , 64 AC power supply

JP 2006-84892 A

Claims (13)

A developer accommodating portion for accommodating a two-component developer containing toner and a magnetic carrier;
Developer agitating means for agitating the two-component developer in the developer accommodating portion to charge the toner in the two-component developer;
A developer carrying member containing a magnetic field generating means and having a rotatable nonmagnetic developing sleeve;
An opening for supplying the toner in the two-component developer to the image carrier at a portion facing the image carrier that carries the electrostatic latent image;
The two-component developer is pumped up from the developer accommodating portion by the magnetic field generating means, is carried on the surface of the developer carrying member, and is transported to a portion facing the image carrier, and through the opening by the magnetic field generating means. In the developing device for supplying the toner to the electrostatic latent image of the image carrier by the magnetic brush formed,
When a movable shutter that opens and closes the opening is disposed and the electrostatic latent image is not formed on the image carrier for a first predetermined time and then the electrostatic latent image is formed on the image carrier. In addition, the opening is shielded by the movable shutter, the developer agitating means and the developing sleeve are operated to charge the toner for a second predetermined time, and then the movable shutter is moved to open the opening. A developing device that controls a movable shutter moving means to move the movable shutter so as to open and supply toner to the electrostatic latent image on the image carrier. The developing device according to claim 1,
When the movable shutter shields the opening of the developer carrier, an interval (L) between the surface of the movable shutter and the surface of the developing sleeve facing the movable shutter is set to the length (M) of the magnetic brush. The developing device is characterized in that the movable shutter is arranged so that L (mm) <M (mm). The developing device according to claim 1 or 2,
On the surface of the movable shutter that contacts the two-component developer carried on the developing sleeve, the average interval (Sm) of the irregularities on the surface is set to the weight average particle diameter (Dv) of the toner in the developer accommodating portion. On the other hand, the developing device is characterized in that a concavo-convex surface is formed so that Sm <Dv, and the content of fine particles in the two-component developer is controlled to be 20% or less. In the developing device according to any one of claims 1 to 3,
Coating the surface of the movable shutter that comes into contact with the two-component developer carried on the developing sleeve with a coating containing a charge control agent that makes the same polarity as the charge polarity of the toner in the two-component developer; A developing device. In the developing device according to any one of claims 1 to 3,
A conductive layer is formed on the surface of the movable shutter that is in contact with the two-component developer carried on the developing sleeve, and a DC bias having the same polarity as the charged polarity of the toner in the two-component developer is applied to the conductive layer. A developing device for applying. 6. The developing device according to claim 5, wherein an AC bias is applied to the conductive layer so as to overlap with a DC bias having the same polarity as the charging polarity of the toner. The developing device according to any one of claims 1 to 6,
A developing device, comprising: a cleaning unit that removes toner adhering to a surface of the movable shutter that contacts the developer carrier when the movable shutter moves.   8. The developing device according to claim 7, wherein the cleaning unit has a roller shape supported by an axial center, and cleans the movable shutter as the movable shutter moves.   9. The developing device according to claim 7, wherein at least a surface of the cleaning unit that contacts the movable shutter is made of an elastic material having a Young's modulus of 5000 Mpa or less.   9. The developing device according to claim 7, wherein at least a surface of the cleaning unit that comes into contact with the movable shutter is formed of a melamine resin foam.   11. The developing device according to claim 7, further comprising a suction mechanism that sucks toner adhering to the cleaning unit in the vicinity of the cleaning unit. In a process cartridge in which an image carrier on which an electrostatic latent image is formed on a surface and a developing device that supplies toner to the electrostatic latent image formed on the image carrier and develops them are integrally connected ,
The process cartridge according to claim 1, wherein the developing device is a developing device according to claim 1. In an image forming apparatus comprising: an image carrier on which an electrostatic latent image is formed on a surface; and a developing device that supplies toner to the electrostatic latent image formed on the image carrier and develops the toner.
The image forming apparatus according to claim 1, wherein the developing device is the developing device according to claim 1.

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