JP5006741B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus for preventing toner from flowing out of a developing device from a photoreceptor.

  In an image forming apparatus using electrophotographic technology, a powdery developer (toner) is often used for development. The image forming apparatus forms an electrostatic latent image on an image carrier such as a photosensitive drum by an LSU (laser scanner unit) or the like according to image information read by an optical system, and visualizes the electrostatic latent image with toner. Then, after the toner image is transferred onto the recording medium, a fixing process is performed.

  However, since the toner is a powder, it easily scatters on the surface other than the surface of the photoreceptor, and when the toner flows out of the developing device such as a housing, it adheres to an optical system such as an exposure lens, a corona wire, and other units. There is a problem that the quality of the finally obtained image is deteriorated.

  In order to solve this problem, it is known that a toner scattering preventing member for preventing toner scattering is provided in a gap formed between the surface of the photoreceptor and the developing device. By providing the toner scattering prevention member so as to be in sliding contact with the surface of the photosensitive member, it is possible to physically close a gap generated between the surface of the photosensitive member and the developing device, and to prevent the toner from scattering to the outside of the developing device. Can be prevented. An elastic member is often used as the toner scattering prevention member.

  However, the photoconductor becomes sensitive to humidity due to the adhesion of discharge products generated by the charger, etc., and when left in a high humidity installation environment such as summer, moisture adsorbs and dew condensation occurs on the surface of the photoconductor. It tends to occur. When an operation for image formation is performed in a state where condensation has occurred, the water adhering to the surface of the photoreceptor is scraped off by the toner scattering prevention member when the photosensitive member rotates, and becomes water droplets on the toner scattering prevention member. Stay. When the electrostatic latent image on the photoconductor passes through the contact portion of the toner scattering prevention member holding the water droplets, the water droplets flow out onto the electrostatic latent image, the charge holding power on the surface of the photoconductor is reduced, and the surface charge is laterally reduced. It will move in the direction. As a result, a so-called “image flow” occurs, causing a problem that the image on the transferred paper is blurred.

In order to solve the above problem, as shown in FIG. 7, both ends of the toner scattering prevention member and outside the electrostatic latent image forming area of the photosensitive member are brought into contact with the photosensitive member, and the toner scattering is caused in the electrostatic latent image forming region of the photosensitive member. A method of forming a slight gap without bringing the prevention member into contact with the photosensitive member has been considered. This solves the problem that water droplets do not stay on the toner scattering prevention member and the image is blurred due to the image flow.
However, since a slight gap is formed between the toner scattering preventing member and the photosensitive member, the problem that the toner flows out of the developing device from the gap has not been solved.

In order to solve these problems, Patent Document 1 discloses a seal operation for bringing the tip of the toner scattering prevention seal into sliding contact with the surface of the photoconductor and bringing the tip of the seal into contact with and away from the surface of the photoconductor. There has been proposed an image forming apparatus provided with a control unit for providing a mechanism and operating the seal operating mechanism for a predetermined time from power-on to separate the seal tip from the surface of the photoreceptor. .
As a result, even when condensation occurs on the surface of the photoconductor, the toner scattering prevention seal can be separated from the photoconductor with respect to the photoconductor that has started rotating for the image forming operation. Since the scattering prevention sheet is always in contact, water droplets staying on the sheet can be prevented from adhering to the electrostatic latent image on the photoreceptor, and adverse effects on image quality can be prevented. In addition, after the water droplets generated on the photosensitive member are dried, the toner scattering prevention sheet can be brought into contact with the photosensitive member again to physically close the gap formed between the photosensitive member surface and the developing device. Can be prevented from scattering outside the developing device.

  However, in the method of Patent Document 1, in addition to the toner scattering prevention sheet, an operation mechanism such as a solenoid for contacting and separating the toner scattering prevention sheet, a control mechanism for controlling the operation mechanism, and the like are required. There is a problem that the configuration is complicated.

Japanese Patent Laid-Open No. 5-224515

  The present invention has been made to solve the above-described problems, and even if condensation occurs on the surface of the photoreceptor, water droplets do not stay on the toner scattering prevention member, thereby preventing the image from flowing. An object of the present invention is to provide an image forming apparatus provided with a toner scattering prevention member that can effectively prevent the toner from flowing out of the developing device with a simple configuration.

  According to the first aspect of the present invention, there is provided a photosensitive member, a developing roller for transporting toner to the photosensitive member, one end attached to a developing housing, the other end in the longitudinal direction of the other end, and formation of an electrostatic latent image on the photosensitive member. An image forming apparatus comprising a toner scattering prevention member that is in sliding contact with the photosensitive member outside the area, wherein the toner scattering prevention member is opposed to the inside of the electrostatic latent image forming area of the photosensitive member. The present invention relates to an image forming apparatus, wherein the contact portion is bent at an acute angle toward the developing roller.

  The invention according to claim 2 relates to the image forming apparatus according to claim 1, wherein the acute angle is 20 ° to 80 °.

  A third aspect of the present invention relates to the image forming apparatus according to the first or second aspect, wherein the photoconductor is made of an amorphous silicon film.

  According to the first aspect of the present invention, the toner scattering prevention member is bent at an acute angle toward the developing roller at the non-sliding contact portion facing the inside of the electrostatic latent image forming region of the photoconductor. The flow of air toward the developing roller in the reverse direction that blocks the flow of air from the developing roller to the outside of the developing device, which is caused by the rotation of the developing roller and the photosensitive drum due to the formation of the bag path, and turns around the vortex. Therefore, the toner can be effectively prevented from flowing out of the developing device. Since the toner scattering prevention member is non-contact in the electrostatic latent image forming region of the photoreceptor, water droplets do not stay on the toner scattering prevention member, and it is possible to prevent the image from flowing. . Since an operation mechanism such as a solenoid or a control mechanism other than the toner scattering prevention member is not required, the toner can be effectively prevented from flowing out of the developing device with a simple configuration.

  According to the second aspect of the present invention, since the acute angle is 20 ° to 80 °, the air flow to the developing roller side in the reverse direction is more effectively cut off and wound in a vortex. Since the flow can be generated more effectively, the outflow of toner can be prevented more effectively.

  According to the invention of claim 3, since the photoconductor is made of an amorphous silicon film, the amorphous silicon photoconductor is more likely to adsorb moisture. Therefore, the toner scattering prevention member according to the present invention is more effectively used. Can be used.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of an image forming apparatus provided with a toner scattering prevention member for preventing outflow of toner to the outside of a developing device according to the invention will be described with reference to the drawings.
FIG. 1 is a view around the developing device of the image forming apparatus according to the present invention. FIG. 2 is a perspective view around the developing device of the image forming apparatus according to the present invention. 3A and 3B are main part extraction diagrams in the vicinity of the toner scattering prevention member of the image forming apparatus according to the present invention. FIG. 3A is a cut end view at a non-sliding portion, and FIG. 3B is a sliding portion. FIG.

  The image forming apparatus 1 according to the present invention includes a photoreceptor 2, a developing roller 3, and a toner scattering prevention member 4.

  The photoreceptor 2 is formed on the outer peripheral surface of the metal substrate on the photoreceptor drum, and is composed of an organic conductive compound. The photosensitive drum is rotatable and rotates counterclockwise in FIG. 1, and an organic photosensitive member (OPC) or an amorphous silicon film is used as the photosensitive member, and is provided at four positions for each of yellow, magenta, cyan, and black. It is done. Amorphous silicon film is particularly sensitive to humidity due to adhesion of discharge products generated by the charger, etc., and easily adsorbs moisture, so when an amorphous silicon film is used as the photoreceptor of the image forming apparatus, In particular, the toner scattering preventing member 4 can be preferably used. Around each photosensitive member 2, a developing device, a charger (not shown), an exposure unit, a drum cleaner, and a static eliminator are provided. The image information of the document read by the optical system is converted into an electrical signal via a mirror, a lens, and a CCD, and then processed. After the laser oscillator is driven and the laser light is reflected by a polygon mirror, An electrostatic latent image is formed on the photoreceptor 2 by irradiating the photoreceptor 2 uniformly charged by the charger.

  The developing roller 3 is disposed in the developing housing 5 and includes a magnetic force generating member 31 having a plurality of magnetic poles, and the magnetic force generating member 31, and toner contained in a developing container (not shown). It consists of a developing sleeve 32 that is pivotally supported so as to be guided onto the surface.

The magnetic force generating member 31 is disposed in the developing sleeve 32 in order to carry the toner on the developing sleeve 32, and is magnetized in multiple poles to form a magnetic field on the surface of the developing sleeve 32.
The developing sleeve 32 has a nonmagnetic conductive hollow cylindrical shape, and is rotatably supported to guide the toner contained in the developing container onto the surface of the photoreceptor 2. The developing sleeve 32 is rotated in the same direction at a portion opposite to the rotation of the photosensitive member 2. The developing sleeve 32 carries the toner contained in the developing container on the surface by the magnetic force of the magnetic force generating member 31, and develops by regulating the thickness of the toner layer formed on the surface of the developing sleeve 32 by a regulating blade (not shown). A thin layer of toner is formed on the sleeve 32 and rotated to convey the toner to the photoreceptor 2.

The toner includes a one-component system composed of a magnetic toner or a non-magnetic toner, or a two-component system composed of a non-magnetic toner or a magnetic toner and a carrier. The image forming apparatus according to the present invention can be used for both one-component toner and two-component toner. In the case of the two-component toner, in addition to the developing roller 3, an intermediate roller 33 that carries only the toner is provided.
FIG. 1 shows an embodiment in which a two-component toner is employed. The toner carried on the developing sleeve 32 is conveyed to the intermediate roller 33 and the intermediate roller 33 carries only the toner. The toner carried on the intermediate roller 33 is conveyed to the photoreceptor 2.

  The toner scattering preventing member 4 is a member that prevents the toner from scattering and flowing out of the developing housing 5 from the gap C1 formed between the photosensitive member and the developing housing. One end of the toner scattering preventing member 4 is attached to the developing housing 5, so that the toner scattering preventing member 4 is fixed. As a method for fixing the toner scattering preventing member 4, a conventionally known method such as screwing or screwing can be employed.

The other end of the toner scattering preventing member 4 is in contact with the photosensitive member 2 at a sliding portion 41 shown in FIG. The sliding portion 41 is in contact with the photoconductor 2 with a contact width (nip width) along the circumferential direction of the photoconductor 2 by bending the end portion of the toner scattering prevention member 4.
On the other hand, the portion of the other end portion of the toner scattering prevention member 4 facing the electrostatic latent image forming region of the photoreceptor 2 is bent at an acute angle toward the developing roller 3 to form a bent portion 42. A slight gap C <b> 1 is formed between the bent portion 42 and the photosensitive member 2, thereby preventing image flow.

  The material of the toner scattering preventing member 4 is not particularly limited. However, since it is in sliding contact with the photosensitive member 2 at the sliding portion 41 even outside the electrostatic latent image forming area of the photosensitive member 2, a polyester film or polyurethane rubber is used. It is preferable to employ a sheet member having a low friction coefficient using an elastic material such as.

  The thickness of the toner scattering preventing member 4 is not particularly limited, but is preferably 0.01 mm to 0.5 mm. If the thickness is less than 0.01 mm, the rigidity of the toner scattering preventing member 4 cannot be maintained. If the thickness exceeds 0.5 mm, the toner scattering preventing member 4 is difficult to be bent at the bent portion 42, which is not preferable in any case.

  The angle a of the bent portion 42 of the toner scattering preventing member 4 shown in FIG. 3 is preferably 20 ° to 80 °. If the angle is less than 20 °, the air flow described later cannot be blocked. If the angle exceeds 80 °, the air flow toward the developing roller 3 in the reverse direction, which causes a vortex, cannot be generated more effectively. Therefore, it is not preferable in any case.

  The length h extending from the bent portion 42 of the toner scattering preventing member 4 shown in FIG. 3 toward the developing roller 3 is preferably 2 mm to 10 mm. This is because if it is less than 2 mm or more than 10 mm, the air flow toward the developing roller 3 in the reverse direction that causes vortices cannot be generated more effectively, which is not preferable. A toner scattering prevention member so that a gap C2 between the leading end extending from the bent portion 42 toward the developing roller 3 and the developing roller 3 in the case of a one-component system and the intermediate roller 33 in the case of a two-component system is minimized. Is preferably folded. This is to prevent the toner from scattering and flowing out.

  As shown in FIG. 6, the toner scattering preventing member 4 is provided at four locations corresponding to the photoreceptor 2 for each of yellow, magenta, cyan, and black, and is provided in the image forming apparatus 1 according to the present invention.

  Hereinafter, the operation of the image forming apparatus provided with the toner scattering preventing member for preventing the toner according to the present invention from flowing out of the developing device will be described. FIG. 4 is a diagram illustrating air flow in an image forming apparatus provided with a conventional toner scattering prevention member. FIG. 5 is a diagram illustrating the flow of air in the image forming apparatus according to the present invention.

  When the user presses a start switch (not shown) of the image forming apparatus 1, the image forming operation is started. In accordance with image information read by the optical system, an electrostatic latent image is formed on the photosensitive member 2 by an LSU (laser scanner unit) or the like, and a one-component toner is used to visualize the electrostatic latent image with toner. When the photosensitive member 2 and the developing roller 3 use two-component toner as shown in FIG. 4, the intermediate roller 33 rotates in addition to the photosensitive member 2 and the developing roller 3.

  When using a one-component toner, the photoreceptor 2 and the developing roller 3 are used. When using a two-component toner as shown in FIG. It is rotated in the same direction. By rotating in the moving direction at the facing portion, an air flow as shown by an arrow is formed. The powder toner rides on the air flow described above and scatters as shown by the arrow, and the toner is developed from the gap C formed between the photoreceptor 2 and the conventional toner scatter preventing member 6 shown in FIG. It flows out of the device.

  On the other hand, as shown in FIG. 5, in the image forming apparatus 1 including the toner scattering prevention member 4 according to the present invention, the toner scattering prevention member 4 is bent by the bent portion 42 to block the air flow. be able to. Since the toner scattering preventing member 4 is bent at an acute angle toward the developing roller 3, an air flow toward the developing roller 3 in the reverse direction is generated as shown in FIG. 5. Since a flow of air toward the developing roller 3 in the reverse direction that vortexes is generated, the leading end extending from the bent portion 42 to the developing roller 3 side, and in the case of a one-component system, the developing roller 3 and the two-component In the case of the system, it is possible to prevent scattering beyond the gap C <b> 2 with the intermediate roller 33. Even if the toner scatters beyond the gap C2, the toner will not scatter to the outside of the developing device unless the gap C1 is exceeded. Therefore, it is possible to prevent the toner from escaping to the outside of the developing device. be able to.

  The present invention is suitably used for an image forming apparatus using powder toner.

FIG. 2 is a view around the developing device of the image forming apparatus according to the present invention. FIG. 3 is a perspective view around the developing device of the image forming apparatus according to the present invention. 3A and 3B are main part extraction views in the vicinity of the toner scattering prevention member of the image forming apparatus according to the present invention, in which FIG. 4A is a cut end view at a non-sliding contact portion, and FIG. It is. FIG. 6 is a diagram illustrating air flow in an image forming apparatus provided with a conventional toner scattering prevention member. FIG. 4 is a diagram illustrating air flow in the image forming apparatus according to the present invention. 2 is a diagram of an image forming apparatus including a toner scattering prevention member. FIG. It is a figure of the conventional toner scattering prevention member.

Explanation of symbols

1. 1. Image forming apparatus Photoconductor 3. Developing roller 4. 5. Toner scattering prevention member Conventional toner scattering prevention member

Claims (3)

A photosensitive member, a developing roller for transporting toner to the photosensitive member, one end attached to the developing housing, the other end in the longitudinal direction of the other end, and outside the electrostatic latent image forming region of the photosensitive member; An image forming apparatus comprising a toner scattering prevention member that is in sliding contact,
The image forming apparatus, wherein the toner scattering preventing member is bent at an acute angle toward the developing roller at a non-sliding contact portion facing the inside of the electrostatic latent image forming area of the photosensitive member.   The image forming apparatus according to claim 1, wherein the acute angle is 20 ° to 80 °.   The image forming apparatus according to claim 1, wherein the photoconductor is made of an amorphous silicon film.

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