JP3758653B2 - Photoconductor polishing apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a photoconductor polishing apparatus that polishes the surface of a photoconductor in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof, and an image forming apparatus including the same. is there.

  In an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile machine, the surface of a photoconductor is charged and exposed to form an electrostatic latent image, and toner supplied from the developing unit to the photoconductor is supplied to the photoconductor. An image is formed on a sheet by performing a series of image forming processes that are attached to the electrostatic latent image, developed as a toner image, transferred to a sheet, and heat-fixed.

  When the image forming process is repeated for a long period of time, a toner component or the like may adhere to the surface of the photoreceptor to form a filming layer. Further, the surface of the photoreceptor may be deteriorated by exposure to an oxidizing atmosphere such as ozone and nitrogen oxide generated by corona discharge during charging. These cause the toner image to blur or blur when the surface of the photoreceptor is exposed to form an electrostatic latent image. In addition, a defect is generated in an image obtained on a paper on which a blurred toner image is transferred, and the print quality is deteriorated. Therefore, it is necessary to remove the filming layer and the deteriorated portion from the surface of the photoreceptor and refresh the surface.

  In a conventional image forming apparatus, a blade for removing untransferred toner is independently provided for a cleaning process for removing untransferred toner remaining on the surface of the photoreceptor. In recent years, a contactless type image forming apparatus uses a cleanerless system in which untransferred toner is collected by a developing device. In this system, untransferred toner is exposed to a developing roller by utilizing a potential difference. It is removed and recovered from the body surface. In any apparatus, when untransferred toner is removed, the toner is brought into contact with the surface of the photoconductor, and the filming layer and the deteriorated portion are ground and removed from the surface of the photoconductor by the polishing function of the toner itself. The surface is refreshed.

Further, in the conventional image forming apparatus, a plurality of blades that clean the adhered matter such as toner and paper dust attached to the surface of the charging roller that is brought into contact with the photosensitive member to charge the surface, and slidably contact and polish the surface. Has been proposed (see, for example, Patent Document 1). Further, in the conventional image forming apparatus, it has been proposed to provide a polishing roller having different surface hardness for rolling contact with the peripheral surfaces of the charging roller, the transfer roller, and the charge eliminating roller. (For example, refer to Patent Document 2).
JP-A-7-175298 JP-A-7-191525

  However, in recent years, from the viewpoints of waste reduction and cost reduction, it has been attempted to increase the life of the photoreceptor by improving the wear resistance. Therefore, there is a tendency to harden the surface of the photoconductor by, for example, polymerizing the material of an OPC (Organic Photo Conductor) photoconductor. On the other hand, the diameter of toner is reduced from the viewpoint of high image quality. For this reason, the toner charge amount distribution is narrowed, so that the resin toner tends to be softened by reducing the molecular weight of the resin toner in order to facilitate fixing of the toner image. Because of these tendencies, it has become difficult to achieve a polishing effect on the surface of the photoconductor due to the polishing function of the toner itself, and even if the toner is brought into contact with the surface of the photoconductor, the film is filled from the surface of the photoconductor. There is a problem that printing quality is deteriorated because the surface of the photosensitive member is not refreshed because the surface of the photosensitive layer is not polished.

  The present invention has been made in view of the above-described circumstances and problems, and is a photoconductor polishing apparatus capable of polishing the surface of a hardened photoconductor to prevent deterioration in print quality, and image formation provided with the same. An object is to provide an apparatus.

To achieve the object, the photoconductor polishing apparatus according to claim 1 is a photoconductor polishing apparatus that polishes the surface of the photoconductor, and a toner that develops an electrostatic latent image formed on the surface of the photoconductor. by polymerization than the resin used for the particles, have a hardness higher than that of the toner particles, the abrasive particles contained in the hopper, the abrasive particles bearing member in contact with the surface of the photosensitive member, the abrasive particles Voltage applying means for applying a voltage to carry the abrasive particles supplied from the hopper to the carrier, a layer thickness regulating member for regulating the layer thickness of the abrasive particles carried on the abrasive particle carrier, It is characterized by having.

  According to a second aspect of the present invention, in the photosensitive member polishing apparatus according to the first aspect, the abrasive particles are colorless and transparent or made of a resin having the same color as the toner particles.

According to a third aspect of the present invention, there is provided an image forming apparatus including the photoconductor polishing apparatus according to the first or second aspect.

  According to the photoconductor polishing apparatus of the first aspect, since the abrasive particle carrier that carries the abrasive particles having a hardness higher than that of the toner particles contacts the surface of the photoconductor, the abrasive particles contact the surface of the photoconductor. In contact with the surface, the surface of the photoconductor is polished and refreshed, so that it is possible to prevent deterioration in print quality. In addition, since the abrasive particles near the abrasive particle carrier are charged by the voltage application means, the abrasive particles can be easily carried on the abrasive particle carrier. Further, since the layer thickness of the abrasive particles carried on the abrasive particle carrier is regulated by the layer thickness regulating member, the layer thickness of the abrasive particles can be made uniform, and the surface of the photoreceptor by the abrasive particles can be made uniform. The polishing amount can be made appropriate.

  According to the photoconductor polishing apparatus of claim 2, since the abrasive particles are colorless and transparent or made of a resin having the same color as the toner particles, for example, the abrasive particles are transferred from the abrasive particle carrier to the surface of the photoconductor and together with the toner particles. Even if it is used for development, the influence on image quality can be reduced.

According to the image forming apparatus of the third aspect , since the photoconductor polishing apparatus is provided, an image forming apparatus having the effect can be obtained.

  For the purpose of providing a photoconductor polishing apparatus capable of polishing the surface of a hardened photoconductor and an image forming apparatus equipped with the same, an abrasive particle carrier for carrying abrasive particles having a hardness higher than that of toner particles is provided. This is realized by making contact with the surface of the photoreceptor.

  Hereinafter, an image forming apparatus including a photoconductor polishing apparatus according to an embodiment of the present invention will be described with reference to the drawings. The image forming apparatus 1 records an image of image data on a sheet by, for example, a copy function, a facsimile function, a (network) printer function, or the like. Specifically, an image of a document read by the copy function, an image of image data received from another G3 facsimile apparatus (not shown), and received from a client PC (not shown) via a LAN (not shown). The image of the image data thus recorded is recorded on a predetermined sheet.

  As shown in FIG. 1, the image forming apparatus 1 includes a photoconductor drum 2 that is a photoconductor that rotates in the direction of an arrow, and charges the surface of the photoconductor drum 2 along the rotation direction of the photoconductor drum 2. The charger 3, the exposure device 4 that forms an electrostatic latent image on the surface of the charged photosensitive drum 2, the developing device 5 that develops the electrostatic latent image and forms a toner image, and transfers the toner image to paper. The transfer device 6, the photoconductor polishing device 7, and a diffusion brush (memory removal brush) 8 that weakens the adhesion of the nontransferred toner remaining on the surface of the photoconductor drum 2 are disposed in order. This is a cleanerless type image forming apparatus that is collected by the developing device 5. The image forming apparatus 1 further includes a paper feed cassette 9, a registration roller 10, a heat roller 11, a press roller 12, a paper discharge roller 13, and a paper discharge tray 14.

  The photosensitive drum 2 is configured by forming a photosensitive layer of OPC (Organic Photo Conductor), amorphous silicon, selenium or the like on the surface of a conductive support such as aluminum formed in a drum shape. An electrostatic latent image is formed on the surface of the drum 2. The charger 3 is a device that uniformly charges the surface of the photosensitive drum 2. Specifically, a corona charger, a charging brush, a charging roller, or the like is used. Here, a scorotron charger is used. It is done. The exposure device 4 is a device that forms an electrostatic latent image on the surface of the photosensitive drum 2 by irradiating the surface of the photosensitive drum 2 with light to remove the charged charges, and an exposure optical system for this purpose. Specifically, an LED (Light Emitting Diode) optical system, a semiconductor laser optical system, or the like is used.

  The developing device 5 is a device that attaches toner to the electrostatic latent image formed on the surface of the photosensitive drum 2 to form a visible toner image. The developing device 5 includes a stirrer 15, a supply roller 16, a developing roller 17, and a layer thickness regulation. The blade 18 is configured. The agitator 15 rotates in the direction of the arrow shown in the figure, agitates the toner stored and accommodated in the developing device 5 and conveys the toner to the supply roller 16 side. A voltage is applied to the supply roller 16, and nearby toner is charged and adheres to the supply roller 16. The toner is transferred from the supply roller 16 by utilizing a potential difference, and the toner is attached to the developing roller 17 that is in pressure contact. The layer thickness regulating blade 18 makes the layer thickness of the toner attached to the outer peripheral surface of the developing roller 17 uniform. The outer peripheral surface of the developing roller 17 to which the toner is attached is rotated while being in contact with the surface of the photosensitive drum 2, and the toner is attached to the electrostatic latent image to form a toner image on the surface of the photosensitive drum 2. The untransferred toner whose adhesion is weakened by the diffusion brush 8 is collected by the developing roller 17 using the potential difference between the photosensitive drum 2 and the developing roller 17, stored and accommodated in the developing device 5, and reused. .

  The transfer device 6 is a device for transferring a toner image formed on the surface of the photosensitive drum 2 to a sheet. Specifically, a conductive roller to which a voltage is applied, a corona charger, or the like is used. A conductive transfer roller is used, and a toner image on the surface of the photosensitive drum 2 is transferred onto a sheet by applying a voltage having a polarity opposite to that of the toner. The diffusion brush 8 weakens and disperses the adhesion force of the untransferred toner remaining on the surface of the photosensitive drum 2 without being transferred to the paper.

  A large number of sheets of a predetermined size are stored in the sheet feeding cassette 9, and the sheets stored in the sheet feeding cassette 9 are separated one by one by the sheet feeding roller 19 and supplied to the sheet conveying path 20. The registration roller 10 conveys the sheet supplied from the sheet feeding cassette 9 between the photosensitive drum 2 and the transfer unit 6 provided with the sheet conveyance path 20 interposed therebetween. The heat roller 11 and the press roller 12 are arranged on both sides of the paper conveyance path 20, and heat the toner image by a heat source provided inside the heat roller 11 while pressing the paper from above and below to form the toner image. Fix to paper. The paper discharge roller 13 discharges the recording paper (paper) on which the image is fixed to the paper discharge tray 14.

  Next, the photoconductor polishing apparatus 7 according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the photoconductor polishing apparatus 7 is a polishing unit disposed so that a casing 71 for storing abrasive particles and a part of the casing 71 exposed from the opening provided on the photoconductor drum 2 side are exposed. Abrasive particle carrying roller 72 which is a particle carrying body, a voltage applying means 73 such as a power source for applying a voltage to abrasive particle carrying roller 72, and a layer thickness of abrasive particles carried on abrasive particle carrying roller 72 are regulated. And a blade 74 which is a layer thickness regulating member.

  The abrasive particles have a hardness higher than that of the toner particles as the main component of the toner, and have a hardness equal to or higher than that of the filming layer and the deteriorated portion of the surface 2 of the photosensitive drum, and the same resin material as the toner particles Consists of. The abrasive particles are made of, for example, a resin such as polyester or styrene acrylic used as a material for the toner particles. However, a resin whose hardness is higher than that of the toner particles by designing a molecular structure by polymerizing the resin used for the toner particles is used as the abrasive particles. The abrasive particles are about the same size as the toner particles, and the color is colorless and transparent or the same color as the toner by adding the same pigment as the toner particles.

  The casing 71 is made of a box-shaped member made of resin or metal, and contains abrasive particles therein, and an opening is provided on the wall surface on the photosensitive drum 2 side. The abrasive particle carrying roller 72 is made of rubber, a sponge member or the like, but the same components as the developing roller 17 can be applied. The abrasive particle carrying roller 72 is installed inside the casing 71 and rotates in the direction indicated by the arrow. The voltage applying unit 73 applies a bias voltage comparable to that of the photosensitive drum 2 to the abrasive particle carrying roller 72. The blade 74 is a member that regulates the layer thickness of the abrasive particles carried on the outer peripheral surface of the abrasive particle carrying roller 72, and is composed of an elastic stainless steel member or the like. It is installed on the lower surface of the opening of the casing 71 so as to elastically contact the downstream side in the transport direction.

  The abrasive particles present in the vicinity of the abrasive particle carrying roller 72 are charged by the bias voltage applied to the abrasive particle carrying roller 72, and the abrasive particles adhere to the surface of the abrasive particle carrying roller 72. The outer peripheral surface of the abrasive particle carrying roller 72 is in pressure contact with the surface of the photosensitive drum 2, and the abrasive particles adhering to the surface of the abrasive particle carrying roller 72 are rotated by the rotation of the abrasive particle carrying roller 72 in the direction indicated by the arrow. It is conveyed to the photosensitive drum 2 side. On the way, the layer thickness of the abrasive particles adhered to the outer peripheral surface of the abrasive particle carrying roller 72 by the blade 74 is regulated to a uniform predetermined thickness.

  When the abrasive particles carried on the outer peripheral surface of the abrasive particle carrying roller 72 are pressed against the surface of the photosensitive drum 2, the filming layer and the deteriorated portion on the surface of the photosensitive drum 2 are removed by the polishing function of the abrasive particles. The surface of the photosensitive drum 2 is refreshed by polishing. Since the abrasive particles are charged to the same level as the surface of the photosensitive drum 2, they do not transfer to the surface of the photosensitive drum 2 while adhering to the surface of the abrasive particle carrying roller 72.

  For example, even if the abrasive particles are transferred to the surface of the photosensitive drum 2 and collected together with the untransferred toner in the developing device 5 and used in the developing process together with the toner, the abrasive particles are the same material as the toner particles. The size of the toner particles is almost the same as that of the toner particles, and the color is colorless and transparent or the same color as the toner. Therefore, the influence on the image quality is very small.

  As shown in FIG. 1, the photoconductor polishing apparatus 7 is disposed between the transfer device 6 and the diffusion brush 8, but is disposed between the diffusion brush 8 and the charger 3. Also good. However, since the abrasive particles transferred from the photoconductor polishing device 7 to the surface of the photoconductor drum 2 are diffused by the diffusion brush 8, it becomes easy to collect the abrasive particles by the developing device 5, and therefore, the transfer device 6 and the diffusion brush 8. It is preferable to dispose the photoconductor polishing device 7 between them.

  Further, as shown in FIG. 2, an image forming apparatus 1 ′ provided with a photoreceptor polishing apparatus 7 ′ according to a modification of the embodiment may be used. The photoreceptor polishing apparatus 7 ′ includes a hopper 75 that stores and supplies abrasive particles above the abrasive particle carrying roller 72. In this case, the casing 71 ′ is provided with an opening on the upper surface of the box-shaped member, but may be a member in which the hopper 75 is installed. The hopper 75 accommodates abrasive particles in a funnel shape, and has a gap at a lower end thereof spaced from the upper end of the abrasive particle carrying roller 72. The gap has a width that is substantially the same as the width of the abrasive particle carrying roller 72 and is longer than the size of the abrasive particles by a predetermined length.

  The abrasive particles accommodated in the hopper 75 are charged when dropped from the gap and are carried on the surface of the abrasive particle carrying roller 72. Since new abrasive particles fall from the hopper 75 and are replenished, the contact surface of the abrasive particle carrying roller 72 is always kept in a preferable state. The hopper 75 may be provided with an opening / closing member that enables opening and closing of the gap, and the falling of the abrasive particles may be controlled by opening and closing the gap at a predetermined interval.

  Next, the printing operation of the image forming apparatus 1 provided with the photoconductor polishing device 7 will be described with reference to the drawings. When the printing process starts, as shown in FIG. 3, the main motor is turned on, the charging bias is turned on (positive), the developing bias is turned on (positive), the transfer bias is turned on (positive), and the memory erase brush bias is turned on (positive). ), And the abrasive particle carrying roller bias is turned ON (positive). Here, the reason why the developing bias is set to ON (positive) is to collect the untransferred toner remaining on the surface of the photosensitive drum 2 by the developing device 5. The reason why the abrasive particle carrying roller bias is set to ON (positive) is to polish the surface of the photosensitive drum 2.

  Thereafter, the transfer bias is turned ON (positive), a test voltage is applied to the transfer roller, and a so-called FB sequence (feedback sequence) is started. The transfer bias voltage at the time of transfer onto the paper is determined according to the current value detected here. After completion of the FB sequence, the transfer device is turned off.

  Next, the photosensitive drum 2 is uniformly charged by the charger 3 and the exposure unit 4 is turned on, whereby an electrostatic latent image corresponding to image information is formed on the surface of the photosensitive drum 2, and the developing unit 5. As a result, toner is attracted to the electrostatic latent image on the photosensitive drum 2 to form a toner image. The reason why the transfer bias is turned on (negative) is to collect the toner adhering to the surface of the transfer roller onto the surface of the photosensitive drum 2. When the sheet reaches the transfer position, the transfer bias voltage is applied to the transfer roller, and transfer is performed. When the printing process is completed, all the main motors and the like are turned off.

  In FIG. 3, when the main motor is ON, the abrasive particle carrying roller bias is always ON (positive), but the present invention is not limited to this. For example, the surface of the photosensitive drum 2 may be polished by turning it on (positive) every predetermined number of prints or turning it on (positive) only for a certain time at the start of the printing process. The number of rotations of the abrasive particle carrying roller 72 and the sign of the applied voltage may be appropriately set according to the abrasive particles and the like.

  In a cleanerless type image forming apparatus, the present invention can be applied to an apparatus that needs to polish the surface of a photoreceptor.

1 is a schematic configuration diagram illustrating an image forming apparatus including a photoconductor polishing apparatus according to an embodiment of the present invention. It is a schematic block diagram which shows the image forming apparatus provided with the photoreceptor grinding | polishing apparatus which concerns on the deformation | transformation of the Example of this invention. 2 is a timing chart of the operation of the image forming apparatus shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photosensitive drum (photosensitive body)
7 Photoconductor polishing device 71 Casing 72 Abrasive particle carrier roller (abrasive particle carrier)
73 Voltage application means 74 Blade (layer thickness regulating member)

Claims (3)

In the photoconductor polishing apparatus for polishing the surface of the photoconductor,
By polymerization than the resin used in the toner particles for developing an electrostatic latent image formed on the surface of the photosensitive member, have a hardness higher than that of the toner particles, the abrasive particles contained in the hopper,
An abrasive particle carrier in contact with the surface of the photoreceptor;
Voltage application means for applying a voltage to support the abrasive particles supplied from the hopper on the abrasive particle support;
A layer thickness regulating member for regulating the layer thickness of the abrasive particles carried by the abrasive particle carrier;
A photoreceptor polishing apparatus comprising:   The photoconductor polishing apparatus according to claim 1, wherein the polishing particles are made of a resin that is colorless and transparent or has the same color as the toner particles. An image forming apparatus comprising the photoconductor polishing apparatus according to claim 1 .

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