JP2015176022A - image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a toner in a developing device in an image forming apparatus from leaking to the outside of the device from a gap between both ends of a developing roller and a housing of the developing device, and prevent a toner trapped between the surface of the developing roller and a seal member from fusing to be adhered to the seal member.SOLUTION: A developing device 3 has a toner seal member 34 provided between areas on both ends of a developing roller 31 where a toner thin layer is not formed and a housing 3A of the developing device 3 arranged opposite thereto. A heat transfer sheet 35, which is obtained by forming a heat conduction material into a sheet shape, is provided between the toner seal member 34 and the housing 3A. The heat transfer sheet 35 has sheet ends 35a exposed to the outside of the housing 3A of the developing device 3. A friction heat is generated between the rotating developing roller 31 and the toner seal member 34, and is emitted to the outside of the device while being propagated along the heat transfer sheet 35.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, or a printing machine.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a facsimile machine, or a printer or a printing machine, a photosensitive member used as a latent image carrier is charged. Charge uniformly. Thereafter, only an image portion is exposed with a laser beam or the like in an exposure process to form an electrostatic latent image, and a visible image is processed with toner supplied from a developing device in the next development process. It is known that after a toner image that has become a visible image on a photoreceptor is transferred to a recording paper such as paper in a transfer process, the toner image is fixed by a fixing device to obtain a copy or a printed output. Yes. The toner remaining on the photoreceptor without being transferred onto the paper in the transfer process is recovered after being removed from the photoreceptor in a cleaning process disposed downstream of the transfer process, and the next image formation is performed again from the charging process. .

  The developing device includes a developing roller having a conductive elastic layer around a metal core, and a conductive foam elastic layer formed around the metal core and conductive fibers. And a supply roller formed from a brush. Further, a toner regulating member composed of a thin metal plate is provided to form a certain amount of toner thin layer on the developing roller. As one of the development methods, a contact one-component development method in which the contained developer mainly includes toner is used.

  In this contact one-component development system, the following is performed. The toner stored in the developing device is supplied while the supply roller is in contact with the developing roller, and the toner sent onto the developing roller is fixed in a certain amount by the toner regulating member that is uniformly in contact with the developing roller in the longitudinal direction. And a predetermined charge amount. Next, the toner thin layer formed on the developing roller is conveyed to a developing nip where the developing roller and the surface of the photosensitive member abut, and is brought into contact with an electrostatic latent image formed on the surface of the photosensitive member in advance to static The toner adheres electrically and forms a visible image with toner on the photoreceptor.

  In this way, the contact one-component development method does not require a magnet roller in the developing roller because a carrier made of a magnetic material is not used in the developer, compared to the conventional two-component development method. In addition, there is no need to provide a hopper that supplies toner into the carrier or a mixing and stirring unit that uniformly mixes and charges the supplied toner and the carrier. For this reason, there is a feature that it is possible to reduce the size and size with a simple configuration. In addition, since the toner thin layer is brought into contact with the electrostatic latent image on the photoconductor, it is difficult to cause image abnormality due to the edge effect, and it is easy to obtain good image quality. Widely adopted in the center.

  However, since only toner exists in the developing device as a developer, its behavior is very unstable compared to the two-component developing method, and it is particularly susceptible to environmental fluctuations and external influences, and the fluidity of the toner is low. It changes significantly and the behavior of the toner inside the developing device changes greatly. For this reason, variations in the toner charge amount due to variations in the toner thin layer amount on the developing roller and triboelectric charging cause a variation in the toner charge amount. It is done.

  Further, since the developer is only the toner, it is very easy to scatter and easily enter a minute gap. For this reason, toner leakage from the bearings of the developing roller and the supply roller in the developing device, particularly from the developing roller provided at the opening of the housing (main body case) of the developing device and the toner regulating member easily occurs. For this reason, it has the subject that it is easy to cause problems, such as a contamination inside a main body, or an abnormal image by the fall on an image. The following measures are taken for toner leakage from the opening of the housing of the developing device. For example, a seal member made of an elastic material such as a nonwoven fabric, a brush, or a sponge is pressed into the gap formed between the housing of the developing device and the toner regulating member and the developing roller, thereby filling the gap and preventing toner leakage from the developing device. Measures such as suppression are generally used and widely used. In particular, the seal member is pressed into the gap between the both ends of the developing roller and the housing of the developing device to bring the seal member into close contact with the surface of the developing roller and the housing of the developing device. The toner is prevented from entering the edge of the developing roller from the layer.

  However, as the pressure is increased in order to bring the seal member into close contact with the developing roller, the torque load generated when the developing roller is driven to rotate increases more easily, and the increase in size and cost associated with the improvement of the motor output becomes a problem. In addition, since the abutting portion is liable to be deteriorated due to sliding under a high pressure and greatly affects the life of the product, a great restriction is likely to occur on the improvement in sealing performance against toner leakage.

  For these problems, a seal member made of a fiber or a low friction material treated with fluorine for the seal member, or a material with high lubricity added in the seal member, or a low hardness with a skin layer is used. A foaming elastic body is used. Accordingly, measures are taken such as reducing the frictional force between the developing roller and the seal member by reducing the pressing force to the developing roller and reducing the torque load generated when the developing roller is driven. Therefore, it is possible to provide a product having no abnormal image even when used for a long time.

  As described above, the effect of reducing the frictional force between the seal member and the developing roller has been used to suppress toner leakage and reduce the driving torque of the developing roller. However, in recent years when there are significant demands for energy saving and low environmental load, toners are being fixed at a low temperature, and toner having a lower melting point is used. When a toner having a low melting point is used, even when a seal member with a reduced frictional force is used, if the toner enters the rubbing portion between the seal member and the developing roller surface, the toner is melted by the frictional heat and becomes a seal member. It may stick. In this case, there is a concern that the surface of the developing roller may be lost, and toner leakage may occur from the end of the developing device.

  According to the present invention, even when a toner having a low melting point is used, the toner does not adhere to the seal member contact portion at the end of the developing roller, and it is possible to perform stable and good image output over a long period of time. An object is to provide an image forming apparatus.

  An image forming apparatus according to claim 1, a charging device that uniformly charges the image carrier, an exposure device that exposes the uniformly charged surface of the image carrier to form an electrostatic latent image, and A developing device that develops the formed electrostatic latent image with a developer to form an image visualized on the image carrier, and the image formed on the image carrier is transferred onto a transfer paper or a transfer belt. An image forming apparatus comprising: a transfer device for transferring; and a cleaning device for removing the developer remaining on the image carrier after transferring the image. The developing device is a roller around the core metal material. A developing roller having a conductive elastic layer having a shape, a developer regulating blade for forming a uniform thin layer of the developer contained in the developing device in a predetermined region on the developing roller, and the developer. A housing for housing at least Visualization by supplying the developer to the electrostatic latent image formed on the image carrier by bringing the developing roller on which the thin layer of developer is formed into contact with the surface of the image carrier. Between the region where the thin layer by the developer is not formed at both ends of the developing roller and the housing of the developing device facing the developing roller surface, A contact member is provided, and a heat transfer sheet is provided between the seal member and the housing of the developing device, and a part of the heat transfer sheet is provided on the housing of the developing device. It is exposed to the outside.

  According to the image forming apparatus of the first aspect, since the seal member is provided in contact with the gap between the both end portions of the developing roller and the housing of the developing device, the toner stored in the developing device is Leakage to the outside of the apparatus through the gap between both ends of the developing roller and the housing of the developing device is suppressed. Further, a heat conductive material is interposed as a heat transfer sheet between the seal member and the housing of the developing device, and a part of the heat transfer sheet is exposed to the outside of the housing of the developing device. Therefore, when the developing roller rotates, frictional heat is generated between the developing roller and the seal member. However, the generated frictional heat is not stored in the sealing member or the housing of the developing device, but moves to the heat transfer sheet, and the heat transfer sheet It is discharged outside the device while traveling inside. By suppressing the temperature rise due to frictional heat generated at the end of the developing roller in this way, it is possible to prevent the toner that has entered between the surface of the developing roller and the seal member from being melted and fixed to the seal member. Accordingly, it is possible to suppress the loss of the developing roller due to the stuck toner and the toner leakage to the outside of the apparatus accompanying the toner.

1 is a configuration diagram of a main part of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a configuration of an entire image forming unit centering on a photosensitive drum in an image forming apparatus of an embodiment. FIG. FIG. 2 is a diagram illustrating details of a system configuration of a photosensitive drum and a developing device in the image forming apparatus according to the embodiment. FIG. 3 is a diagram of a developing device in the image forming apparatus according to the embodiment as viewed from the photosensitive drum side. FIG. 3 is a diagram illustrating a configuration example of a toner seal member and a heat transfer sheet of a developing device in the image forming apparatus of the embodiment. FIG. 6 is a diagram illustrating another configuration example of a toner seal member and a heat transfer sheet of a developing device in the image forming apparatus according to the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 6. FIG. 1 is a configuration diagram of a main part of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of the entire image forming unit centering on the photosensitive drum in the image forming apparatus of the embodiment. FIG. 3 is a diagram showing details of the system configuration of the photosensitive drum and the developing device in the image forming apparatus of the embodiment. FIG. 4 is a view of the developing device in the image forming apparatus according to the embodiment as viewed from the photosensitive drum side.

  The image forming apparatus of this embodiment is a multi-color image forming apparatus, and image forming units 10Y, 10M, 10C, and 10BK corresponding to yellow, magenta, cyan, and black colors are arranged in parallel in the order of each color. Yes. The image forming units 10Y, 10M, 10C, and 10BK are each provided with a transfer device 5, and an exposure device 6 is provided above the image forming units 10Y, 10M, 10C, and 10BK.

  Each of the image forming units 10Y, 10M, 10C, and 10BK includes a photosensitive drum 1 that is an “image carrier”, a charging device 2 that is disposed around the photosensitive drum 1, a developing device 3, and a cleaning device. 4 is provided. The photosensitive drum 1 has a photoconductive layer made of an organic material such as OPC (organic photoconductor) on its surface, and can rotate in forward and reverse directions. The charging device 2, the exposure device 6, the developing device 3, and the cleaning device 4 execute an image forming process on the photosensitive drum 1 along the positive rotation direction of the photosensitive drum 1.

  The charging device 2 includes a charging roller 21, and the charging roller 21 is brought into contact with the surface of the photosensitive drum 1 by urging means (not shown) provided at both ends thereof. The charging roller 21 is set to be driven to rotate as the photosensitive drum 1 is driven by the frictional force generated by the pressing of the surface of the photosensitive drum 1 and the charging roller 21. At the same time, a DC voltage or a superimposed voltage of DC and AC is applied to the charging roller 21 from a high voltage power source (not shown) provided on the main body side, so that the photoconductive layer formed on the surface layer of the photosensitive drum 1 is made uniform. It comes to be charged. The charging roller 21 is formed by integrally bonding a conductive elastic layer made of a medium resistance material to a base material made of silicone rubber or the like around a conductive metal core. Furthermore, the surface is covered with a very thin high-resistance thin film having a thickness of 4 μm and several tens of μm and a coating layer with improved toner releasability.

  When the photosensitive drum 1 is charged, exposure is started in response to the input image toward the photosensitive drum 1 that is uniformly charged by the exposure device 6, and an invisible electrostatic image is formed on the photosensitive drum 1. A latent image is formed.

  In the developing device 3, for example, a thin toner layer is formed on the surface of the developing roller 31 having a conductive elastic layer around a metal core, and the developing is performed by bringing the toner thin layer into contact with the surface of the photosensitive drum 1. A component developing device is used. That is, the toner as “developer” which is thinned on the developing roller 31 and charged to a predetermined charge amount is formed in the developing nip portion formed by the contact between the developing roller 31 and the surface of the photosensitive drum 1. Be transported. Then, the toner is electrostatically attached by contacting the electrostatic latent image previously formed on the surface of the photosensitive drum 1, and a visible image is formed on the photosensitive drum 1 by the toner. As for the toner, an external additive used for the toner base is one in which at least one of the external additives contains hydrophobic silica whose surface is treated with silicone oil (for example, a silica compound). doing.

  The transfer device 5 includes a transfer belt 51 wound around driving rollers R1 and R2, a primary transfer roller 52 provided in the transfer belt 51, and a secondary transfer roller 53 disposed in contact with the surface of the transfer belt 51. And a transfer cleaning unit 54. The primary transfer roller 52 can be brought into contact with and separated from the surface of the photosensitive drum 1 of each color via the transfer belt 51. The transfer cleaning unit 54 is configured to remove and collect toner (developer) remaining on the transfer belt 51 that has passed through the secondary transfer roller 53.

  The visible images formed on the photosensitive drum 1 are sequentially transferred to the transfer belt 51 by the image forming units 10Y, 10M, 10C, and 10BK for the respective colors. That is, by applying a bias voltage from the high voltage power source to the primary transfer roller 52 at the contact portion between the photosensitive drum 1 and the transfer belt 51, a visualized image (toner image) on the photosensitive drum 1 is transferred to the transfer belt 51. The image is transferred upward to form a color image.

  The color image formed on the transfer belt 51 is transferred to transfer paper fed out from a paper feeding device after setting a registration timing by a registration roller (not shown). That is, a bias voltage is applied from a high-voltage power supply to the secondary transfer roller 53 that is disposed so as to be sandwiched between the driving roller R2 in the transfer belt 51 and is set to be rotatable. As a result, the color image (toner image) on the transfer belt 51 moves onto the transfer paper and is transferred onto the transfer paper. The transfer paper on which the color image has been transferred by the transfer device 5 is conveyed to the fixing device 7, and the color image is fixed on the transfer paper by being pressed and heated by the fixing device 7, and is discharged to a paper discharge tray (not shown). Is done.

  On the other hand, the residual toner on the photosensitive drum 1 after passing through the contact portion with the transfer belt 51 moves to the cleaning device 4 provided downstream in the rotation direction of the photosensitive drum 1. The cleaning device 4 is arranged such that a blade 41 made of an elastic material based on urethane comes into contact with the photosensitive drum 1 at a predetermined angle and pressure. Then, most of the residual toner is scraped off from the surface of the photosensitive drum 1 by the blade 41, so that the surface of the photosensitive drum 1 is kept clean and the next image can be formed. The scraped toner is conveyed to a collecting unit (not shown) by a developer conveying means 42 having a screw shape provided inside the cleaning device 4. The surface of the photosensitive drum 1 that has passed through the cleaning device 4 moves to the charging device 2 again, and image formation in the next process is performed. In this embodiment, the image is formed on the transfer paper via the transfer belt 51, but the image may be formed directly on the transfer paper moved by the transport belt. In this case, the transfer belt that makes the transfer paper contact with the photosensitive drum 1 becomes the “transfer device”.

  Next, the developing device 3 will be described. The developing device 3 includes a developing roller 31 and a supply roller 32 at a lower portion of a housing 3A constituting the main body case. In the housing 3A, a predetermined amount of toner T (see FIG. 2) as a “developer” is initially stored or supplied from a toner cartridge provided outside. The toner T in the housing 3 </ b> A is sent while being stirred to the supply roller 32 by the stirring paddle 37 provided in the housing 3 </ b> A, and is then conveyed and supplied to the developing roller 31 by the supply roller 32.

  The supply roller 32 is formed by forming a foamed elastic layer having a structure having pores (cells) around a metal core. The holes (cells) take in the toner by adhering efficiently, and prevent deterioration of the toner due to pressure concentration at the contact portion with the developing roller 31. The foamed material is set to have an electric resistance value of 3 to 14 Ω. Further, an offset voltage is applied to the supply roller 32 as a supply bias voltage so as to have the same polarity as the toner charging polarity with respect to the potential of the developing roller 31. The supply bias voltage acts in a direction in which the toner preliminarily charged at the contact portion with the developing roller 31 is pressed against the developing roller 31. However, the polarity of the voltage applied to the supply roller 32 is not limited to this, and the same potential or polarity as the developing roller 31 may be reversed depending on the type of developer.

  The supply roller 32 rotates in the counterclockwise direction in the figure, and applies the toner adhered to the surface to the surface of the developing roller 31. Note that a brush made of conductive fibers can be used for the supply roller 32 instead of the foamed elastic layer, and can be appropriately selected according to its purpose and cost.

  The developing roller 31 is made of a metallic cored bar formed of a conductive elastic body in the shape of a roller, and further has a surface coat layer made of a material that is easily charged with a polarity opposite to that of the toner. Is provided. The elastic material of the developing roller 31 is set to a hardness of 50 degrees or less according to JIS-A in order to keep the contact state with the photosensitive drum 1 uniform. Furthermore, in order to make the developing bias voltage act, the electric resistance value is set to the third power to the tenth power Ω, and the surface roughness Ra is set to 0.2 to 2.0 μm, so that the toner amount necessary for the development can be increased. It is held on the surface of the developing roller 31.

  The toner sent onto the developing roller 31 is formed into a certain amount of toner thin layer by a toner restricting member 33 as a “developer restricting blade” shown in FIG. 2 and has a predetermined charge amount due to frictional charging. It is done. The toner regulating member 33 is made of a conductive material, and is in contact with the surface of the developing roller 31 evenly in the longitudinal direction.

  In this embodiment, a metal leaf spring material such as SUS304CSP, SUS301CSP, or phosphor bronze is used as the toner regulating member 33, and the free end thereof is brought into contact with the surface of the developing roller 31 with a pressing force of 10 to 100 N / m. The toner passing under the pressing force of the toner regulating member 33 is thinned, and a predetermined charge is applied to the toner by frictional charging with the surface of the developing roller 31. Further, a voltage that is offset to the same polarity as the charging polarity of the toner with respect to the potential applied to the developing roller 31 is applied to the toner regulating member 33 as a regulating bias voltage in order to assist frictional charging.

  The surface of the developing roller 31 moves in the same direction as the movement direction of the photosensitive drum 1 at a position facing the photosensitive drum 1 with respect to the photosensitive drum 1. Then, the toner thinned by passing through the contact nip with the toner regulating member 33 is conveyed by the developing roller 31 to the developing nip portion formed by the contact between the developing roller 31 and the surface of the photosensitive drum 1. Is done. A bias voltage having the same polarity as the toner is applied to the developing roller 31 through a shaft end of the developing roller 31 from a power supply unit (not shown) provided on the main body side to form a potential potential. The toner that has reached the development nip moves to the surface of the photosensitive drum 1 in accordance with the electrostatic latent image previously formed on the surface of the photosensitive drum 1 by the above-described potential potential. A visualized image is formed on the toner 1 with toner.

  Part of the housing 3A of the developing device 3 is in contact with the developing roller 31 and the housing 3A at positions facing both end portions 31a and 31a (see FIG. 4) of the developing roller 31, which is a region where a toner thin layer is not formed. In order to avoid this, a gap G (see FIGS. 3 and 5) is formed. This gap G is about 0.5 to several mm. In order to prevent the toner in the developing device 3 from leaking from the gap G to the outside of the housing 3A, a toner seal member 34 as a “seal member” is provided. That is, as shown in FIGS. 4 and 5, the toner seal member 34 is provided between the end portions 31a, 31a of the developing roller 31 where the toner thin layer is not formed and the housing 3A. The toner seal member 34 is made of a foamed elastic material mainly composed of polyurethane (PU), polyolefin / polyethylene (PE), rubber / EPDM (RS), PTFE, or fluorine rubber. Moreover, you may use the nonwoven fabric and electrostatic flocking brush which consist of a PTFE fiber instead of a foaming elastic material.

  As shown in FIG. 5, when the developing roller 31 is mounted, the toner seal member 34 is pressed against the surface of the developing roller 31 to be compressed and deformed, and is in close contact with the surface shape of the developing roller 31. In this way, even if the toner inside the developing device 3 tries to move from both end portions 31a and 31a of the developing roller 31 to the outside, the toner seal member 34 can prevent entry. In addition, a sheet-like heat transfer sheet 35 made of a material having a higher thermal conductivity than the toner seal member 34 is interposed between the toner seal member 34 and the housing 3A of the developing device 3. That is, the toner seal member 34 is a heat conductive material, and when the heat conductivity is θ (W / m · K) and the heat conductivity of the heat transfer sheet 35 is θ ′ (W / m · K), θ <Θ ′. The heat transfer sheet 35 is disposed along the shape of the housing 3A so as to be in close contact with the toner seal member 34. Further, the sheet end 35a, which is a “part” of the heat transfer sheet 35, is disposed in the housing 3A of the developing device 3. It is exposed outside. The heat transfer sheet 35 is made of a foil copper plate and is fixed to the housing 3A.

  The frictional heat generated by the rubbing between the rotating developing roller 31 and the toner seal member 34 is not limited to the inside of the toner seal member 34 but moves to the copper heat transfer sheet 35 having a higher thermal conductivity, It is guided to the outside of the developing device 3 through the inside of the heat transfer sheet 35. The sheet end portion 35 a (exposed portion) of the heat transfer sheet 35 is bent into a continuous rectangular shape and fixed to the outer wall of the developing device 3. That is, the sheet end portion 35a of the copper heat transfer sheet 35 exposed to the outside of the housing 3A of the developing device 3 is formed into a continuous rectangular shape. By making it rectangular in this way, the surface area increases, heat dissipation can be further improved, and cooling can be performed more efficiently.

  Further, as shown in FIG. 6, the sheet end portion 35a exposed to the outside of the housing 3A of the developing device 3 for the heat transfer sheet 35 may be formed into a fin shape. Furthermore, it is good also as a fin shape by mounting | wearing with the fin for heat radiation of another member on the heat-transfer sheet | seat 35. FIG. The material of the heat transfer sheet 35 is preferably a metal such as copper or aluminum having a high thermal conductivity, but may be a resin material or the like as long as it is at least larger than the thermal conductivity of the toner seal member 34.

  Further, a cooling fan as a “cooling device” is provided on the main body side of the image forming apparatus to cool the inside of the apparatus, and an air flow is also generated around the developing device 3. The sheet end portion 35a of the heat transfer sheet 35 exposed to the outside of the housing 3A of the developing device 3 is placed on the air flow formed by the cooling fan, and the heat transfer is performed by the air flow hitting the heat transfer sheet 35. It has been confirmed that the sheet 35 is deprived of heat and cooled. In particular, it has been confirmed that the cooling efficiency is further improved by arranging the sheet end portion 35 a having a continuous rectangular shape of the heat transfer sheet 35 on the air flow path.

  It is desirable that the toner seal member 34 and the heat transfer sheet 35 are directly pressed and adhered to each other. However, when adhesion is required, a double-sided tape or an adhesive is used as an “adhesive material” having a high thermal conductivity. ing. In this way, a part of the frictional heat generated when the toner seal member 34 in contact with the developing roller 31 slides in pressure contact is moved from the inside of the developing device 3 to the outside of the device. As a result, the temperature rise at the rubbing portion can be suppressed, and even when the toner enters the rubbing portion of the toner seal member 34, the toner can be prevented from sticking inside, and the toner can be kept for a long time. It is possible to provide an image forming apparatus having no leakage.

  As described above, according to the embodiment, the material used for the heat transfer sheet 35 has a higher thermal conductivity than the toner seal member 34 brought into contact with the heat transfer sheet 35. Accordingly, a part of the frictional heat generated by the rubbing between the toner seal member 34 and the surface of the developing roller 31 can be transferred from the inside of the toner seal member 34 to the heat transfer sheet 35 having higher thermal conductivity. Become. As a result, the temperature rise due to frictional heat generated at both end portions 31a and 31a of the developing roller 31 can be suppressed, and the toner that has entered between the surface of the developing roller 31 and the toner seal member 34 is melted and becomes a toner seal member. Prevent sticking. Therefore, it is possible to suppress the loss of the developing roller 31 due to the adhered toner and the toner leakage to the outside of the apparatus accompanying therewith (claim 2).

  In addition, by setting the thermal conductivity of the sheet material used for the heat transfer sheet 35 to 1.0 (W / m · K) or more, the temperature rise due to the frictional heat generated at both end portions 31a and 31a of the developing roller 31 is clear. It has been confirmed that it can be suppressed. Thereby, the said temperature rise can be suppressed (Claim 3).

  Further, by forming the sheet end portion 35a exposed to the outside of the developing device 3 of the heat transfer sheet 35 into a heat radiating fin shape, the surface area of the heat transfer sheet outside the device is remarkably increased. The transferred heat can be efficiently discharged outside the apparatus. Thereby, the frictional heat generated at both end portions 31a and 31a of the developing roller 31 is easily moved to the heat transfer sheet as needed. Therefore, for example, even in a high-speed machine in which the rotation speed of the developing roller 31 is likely to increase, toner sticking between the surface of the developing roller 31 and the toner seal member 34 hardly occurs, and a stable image can be provided. (Claim 4).

  Further, the sheet end portion 35a of the heat transfer sheet 35 is disposed so as to come into contact with the airflow in the apparatus by a cooling fan provided on the main body side of the image forming apparatus. That is, it arrange | positions so that connection with a spirit medicine apparatus is possible. As a result, the sheet end portion 35a of the heat transfer sheet 35 is always positively cooled, so that the frictional heat generated at the both end portions 31a and 31a of the developing roller 31 is easily transferred to the heat transfer sheet 35 at any time. Therefore, even in a high-speed machine in which the number of rotations of the developing roller 31 is likely to increase as described above, toner sticking hardly occurs, and a stable image can be provided.

  Further, when fixing between the toner seal member 34 and the heat transfer sheet 35, the adhesive and the double-sided tape to be used use a material having high thermal conductivity. Therefore, the frictional heat generated at the end of the developing roller easily moves to the heat transfer sheet as needed, and the toner sticking hardly occurs even in the high speed machine in which the number of rotations of the developing roller 31 is likely to increase similarly to the above. An image can be provided (claim 6).

  Further, as the toner, an external additive used for the toner base is used which contains a hydrophobic silica compound treated with a silicone oil at least on the surface. The silicone oil used in the external additive is gradually extracted also on the developing roller 31 to cover and enlarge the surface of the developing roller 31 and spread to both end portions 31a and 31a of the developing roller 31. The developing roller 31 coated with silicone oil has a reduced friction coefficient, a reduced friction coefficient of the toner seal member 34 containing toner, a reduced rubbing force, and reduced frictional heat. Accordingly, the temperature can be further suppressed, and the toner sticking between the surface of the developing roller 31 and the toner seal member 34 hardly occurs, and a stable image can be provided.

  Further, as the material used for the toner seal member 34, a non-woven fabric made of low friction coefficient fibers may be used, so that a rubbing force with the surface of the developing roller can be obtained by using a fluorine treated fiber such as a fluororesin. Is reduced. Further, since the contact area of the developing roller 31 can be reduced by using a non-woven fabric as compared with the case of using a normal elastic body, the frictional force is less, the temperature rise is suppressed low, and the heat transfer sheet of the embodiment By combining with 35, a more stable image can be provided. Moreover, you may use the brush knitted with the same fiber instead of the nonwoven fabric (Claim 8).

  Further, by using a foamed elastic body mainly composed of polyurethane or the like as the toner seal member 34, compression deformation is facilitated, the adhesion between the toner seal member 34 and the developing roller 31 is improved, and sliding is possible even during sliding. It is difficult for toner to enter the rubbing portion. Therefore, it is possible to provide a stable image by making it difficult for the melted toner to adhere and enter.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

1 Photosensitive drum (image carrier)
2 Charging device 21 Charging roller 3 Developing device 3A Housing 31 Developing roller 31a End 32 Supply roller 33 Toner regulating member (developer regulating blade)
34 Toner seal member (seal member)
35 Heat transfer sheet 35a Sheet end (part)
4 Cleaning device 41 Blade 42 Developer transport means 5 Transfer device 51 Transfer belt 52 Primary transfer roller 53 Secondary transfer roller 54 Transfer cleaning unit 6 Exposure device 7 Fixing device T Toner (developer)
G gap

JP 2001-228709 A

Claims (9)

A charging device for uniformly charging the image carrier, an exposure device for exposing the uniformly charged surface of the image carrier to form an electrostatic latent image, and developing the formed electrostatic latent image A developing device that forms an image visualized on the image carrier by developing with an agent, a transfer device that transfers the image formed on the image carrier onto a transfer paper or a transfer belt, and the image In an image forming apparatus comprising: a cleaning device that removes developer remaining on the image carrier after being transferred;
The developing device includes a developing roller having a roller-shaped conductive elastic layer around a cored bar material, and a uniform thin layer of a developer stored in the developing device. At least a developer regulating blade formed in the region and a housing for housing the developer, wherein the developing roller on which a thin layer of developer is formed is brought into contact with the surface of the image carrier To form an image visualized by supplying the developer to the electrostatic latent image formed on the image carrier,
A seal member that comes into contact with the surface of the developing roller is provided between a region where the thin layer by the developer is not formed at both ends of the developing roller and the housing of the developing device facing the developing roller. A heat transfer sheet is provided between the seal member and the housing of the developing device, and a part of the heat transfer sheet is exposed to the outside of the housing of the developing device. Image forming apparatus.   When the thermal conductivity of the sealing member is θ (W / m · K) and the thermal conductivity of the heat transfer sheet is θ ′ (W / m · K), θ <θ ′. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein the heat transfer sheet has a thermal conductivity of 1.0 (W / m · K) or more.   4. The image formation according to claim 1, wherein at least a part of the heat transfer sheet exposed to the outside of the housing of the developing device has a fin shape. 5. apparatus.   2. The heat transfer sheet, wherein at least a part of an exposed portion of the developing device to the outside of the housing is connectable to a cooling device provided on a main body side of the image forming apparatus. 5. The image forming apparatus according to claim 4.   The image forming apparatus according to claim 1, wherein the heat transfer sheet and the seal member are fixed with an adhesive material having thermal conductivity.   The image forming apparatus according to claim 1, wherein the external additive used for the developer contains a silica compound containing silicone oil.   3. The image forming apparatus according to claim 1, wherein the seal member is made of a fluorine-treated fiber, a non-woven fabric or a brush having a low friction coefficient. 4.   The image forming apparatus according to claim 1, wherein the seal member is made of a foamed elastic body.

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