JP2008203729A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem that a transfer belt and a photoreceptor belt are damaged and the rotation of the transfer belt and the photoreceptor belt varies, because when for instance, a temperature gradient occurs at both sides inside an image forming apparatus, the transfer belt and the photoreceptor belt deviate to one side due to the fact that the length of the transfer belt and that of the photoreceptor belt are changed at both sides. <P>SOLUTION: In the image forming apparatus using a belt-like image carrier 5, a temperature adjusting means 15 is installed adjacent to the belt-like image carrier 5 in the image forming apparatus. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to a transfer belt unit or a photoreceptor belt unit thereof.

  An electrophotographic image forming apparatus includes a developing unit that contains a developer, an image carrier that forms a toner image, and a fixing unit that fixes a sheet onto which toner has been transferred. Components that generate heat, such as a motor that drives the components and a control board that includes a controller, are disposed in the image forming apparatus. Further, for the purpose of preventing temperature rise, cooling parts such as a fan for taking in the outside air or releasing the heat inside the apparatus to the outside air are arranged (for example, refer to Patent Documents 1 and 2).

JP 2004-184450 A JP-A-8-44220

  In general, fixing devices arranged in an image forming apparatus, components that generate heat such as a motor and a control board, and cooling components such as a fan are not evenly arranged on the left and right, so that the left and right temperatures of process components are often different. In particular, the photosensitive belt and the transfer belt are unbalanced in the circumference of the belt due to the difference between the left and right temperatures, and the belt meanders. There has been a problem that the image quality deteriorates due to the belt meandering or the image position failure due to the meandering of the belt. In some cases, parts could fail.

  An object of the present invention is to provide a high-quality image forming apparatus that prevents belt meandering by reducing the temperature gradient inside the image forming apparatus, in particular, the temperature difference between the left and right of the photosensitive belt or transfer belt. .

  In order to achieve the above object, the present invention provides an image forming apparatus having a belt-like image carrier such as a transfer belt or a photosensitive belt, for example, next to the belt-like image carrier in the image forming apparatus. A temperature adjusting means such as a container or a heating means is provided.

  Further, the present invention is characterized in that at least one temperature detecting means is installed next to the belt-shaped image carrier in the image forming apparatus.

  The present invention is configured as described above, and by reducing the temperature gradient inside the image forming apparatus, the meandering of the belt is prevented and the service life is extended, and also the rotation of the belt is prevented and high-quality image forming apparatus is prevented. Can be provided.

  The parts that generate heat in an electrophotographic image forming apparatus include a fixing device, a motor, a control board, and a power supply, but not all parts are evenly arranged on the left and right, and cooling parts such as fans Are not evenly arranged on the left and right.

  Since left and right temperature gradients occur in the image forming apparatus, the left and right dimensions of the process parts are slightly shifted. In particular, since the photosensitive belt, the transfer belt, the conveyance belt, and the like are belt-shaped, the length of one round varies depending on the temperature. As the temperature increases, the belt becomes longer.

  Generally, polycarbonate (PC) alloy, polytetrafluoroethylene (PTFE) alloy, polyimide (PI) alloy, or the like is used for the belt. This has a larger coefficient of thermal expansion than the metal material of the shaft that supports the belt, and the belt becomes slack. The left and right belt slack changes due to the temperature difference between the left and right, and the tension becomes uneven. In general, since the belt tends to move toward a direction where the tension is weak, the belt tends to move toward a warmed direction.

  The present invention has an effect of preventing a temperature difference between the left and right inside the image forming apparatus and reducing the deviation of a belt-like image carrier such as a photoreceptor belt or a transfer belt. Further, by reducing the deviation of the belt, problems such as belt breakage and belt rotation failure can be eliminated.

  Embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, an image forming apparatus to which the present invention is applied includes a belt-like photoreceptor 1, a charger 2 that charges the belt-like photoreceptor 1, an exposure device 3 that exposes the belt-like photoreceptor 1, and development. The apparatus 4 includes a belt-like intermediate transfer member 5, a cassette 8 for storing paper, a paper feed roller 9, a transfer roller 10 facing the intermediate transfer member 5, and a fixing device 11 for fixing toner. Yes.

<Fan>
Generally provided cooling fans are provided for heat sources such as optical scanner motors and scanner drivers, drive motors and motor drivers, and power supplies, and exhaust air that has been warmed by the heat sources or take in outside air. . However, in the cooling fan, the temperature difference between the belt-shaped image carriers cannot be reduced.

  As a first embodiment, a case where a circulation fan which is an air conditioner is provided inside the image forming apparatus will be described. The circulation fan is disposed beside the belt-shaped carrier inside the image forming apparatus. By being provided on the side of the photosensitive belt 1 or on the side of the belt-shaped intermediate transfer member 5, the temperature around the belt is made uniform by circulating the air around the belt and the difference in the belt circumferential length is prevented. .

  In FIG. 1, an air conditioning unit as a temperature adjusting unit, specifically, an air conditioner 15 for a circulation fan is provided on the side of a transfer belt which is a belt-shaped intermediate transfer member 5 and is driven according to control of a control board 14 which is a calculation unit. . The fan is controlled in accordance with the driving of the motor 16 which is a driving means for driving the photosensitive member. Further, by providing the temperature sensor 13 as temperature detecting means, the temperature rise can be detected, and the fan is driven when the temperature rises.

  As shown in FIG. 2, since the temperature of the transfer belt 24 near the fixing device 28 is likely to rise, a circulation fan 30 is disposed in the vicinity of this portion. Since the circulation fan 30 stirs (circulates) the air around the transfer belt, it may be directed in either direction, but the inlet and outlet of the fan are not closed. Desirably, the fan 30 is stood up and installed in such a direction that the mouth opens to the left and right. Furthermore, if a part where the temperature is likely to rise is known, the fan is driven to circulate the air at that part.

  In the case of FIG. 2, since the fixing fan 29 is arranged beside the fixing device 28, the air warmed by the fixing device flows in the direction E, so the temperature in the direction E is higher than the direction F. Similarly, when the transfer belt 24 and the photosensitive belt 20 are also warmed, the direction C is easier to warm than the direction D and the direction A is warmer than the direction B. As shown in FIG. 8, the warmed belt has a longer circumference, and a difference occurs in the circumference between the left side (L side) and the right side (R side) of the transfer belt. As a result, the transfer belt 24 approaches the L side or the R side. Since the temperature in the direction C rises, the L side of the transfer belt 24 becomes longer, and the transfer belt 24 moves closer to the R side of the transfer belt 24 where the circumference does not extend. Now, by disposing the fan 30, the temperature gradient and the left / right temperature difference are reduced, and the difference in circumference is reduced. As a result, belt-induced image defects such as belt breakage and belt rotation unevenness can be eliminated, and high-quality images can be obtained.

  The position of the circulation fan 30 is ideally disposed near the center of the sheet, and the movement of the fan is determined according to the temperature difference between the left and right. There is a method of driving the fan in a continuous printing or long-time power-on state where the temperature difference between the left and right seems to have increased, and stopping the fan after a predetermined time when the sleep state is entered. The fan speed, time, and direction should be changed sequentially for the expected temperature difference.

  In addition, the position of the circulation fan can be freely arranged from the left end to the right end, but the entrance and exit of the fan must not be blocked.

  The transfer belt 24 is supported by at least two shafts 25 and 26 and a shaft 27 that applies tension to the transfer belt 24. Similarly, the photoreceptor belt 20 is supported by rollers 21 and 22 and a shaft 23. In this way, in an image forming apparatus that transfers a toner image with a belt, the image forming apparatus is particularly susceptible to the difference in temperature between the left and right, and the effects of the present invention are likely to occur.

  As shown in FIG. 3, the circulation fan 31 may be provided on the lower side of the belt-shaped image carrier 20 such as on the lower side of the transfer belt. In some cases, a circulation fan 32 may be provided in the lateral direction of the belt-shaped image carrier 20 as shown in FIG. In either case, air is allowed to flow so as to reduce the difference in temperature between the left and right sides of the belt, thereby reducing the amount that the belt approaches.

<Fluid container>
As a second embodiment, a case where a fluid (not shown) and a container 33 for holding fluid are provided inside the image forming apparatus will be described with reference to FIG. The fluid used here is generally water, but there is no problem even if it is oil. A mixed fluid containing water or oil may be used, but a non-volatile fluid is desirable. The fluid is stored in a closed container. A container inlet / outlet and a lid may be provided for taking in and out of the fluid, but the container is usually used with the lid closed.

  The container 33 is disposed on the side of the belt 24 or the belt-shaped image carrier 20 so as to extend left and right. As a result, when a temperature difference is generated between the left and right, the fluid circulates and reduces the temperature difference applied to the belt. The container 33 can be shielded from heat by being disposed between a part such as the fixing device 28 that generates a temperature difference between the left and right and the belt 24 or the belt-shaped image carrier 20, and further reduces the temperature difference. Has the effect of

<Fluid circulation>
Further, as a third embodiment, a case will be described in which there is a container 34 for holding fluid inside the image forming apparatus as shown in FIG. 6, and there is a circulation means 35 for circulating the fluid. By providing the container with a pump, which is the circulation means 35 for circulating the fluid, the temperature difference between the fluids can be further reduced, and the temperature difference between the belt surroundings can be reduced. The pump may use any method, such as a method using a stirring blade and a motor, a method using expansion and contraction of constituent members and a pressure difference using a valve. When a magnetic fluid is used as the fluid, the fluid may be circulated using a linear motor or the like.

<Heater>
As a fourth embodiment, a case where a heater which is a temperature adjusting means is provided inside the image forming apparatus will be described. In order to prevent a temperature gradient from occurring when the image forming apparatus is operated and the temperature inside the image forming apparatus rises, a heater is used at a portion where the temperature is low. The heater is used to reduce the temperature gradient, and in addition to energizing constantly, the temperature is adjusted by intermittent energization to reduce the temperature difference between the left and right. Heaters 36 and 37 as heating means may be provided on the left and right as shown in FIG.

<Temperature detection>
As a fifth embodiment, a case where the temperature sensor 13 is provided inside the image forming apparatus will be described. When the temperature sensor 13 is provided inside the image forming apparatus in combination with the above-described embodiment, the temperature increase inside the image forming apparatus can be detected, so that the temperature increase after the image forming apparatus is turned on is known. In response to the temperature rise value, the temperature difference reduction control as in the above-described embodiment is performed. Specifically, it is desirable to control at a temperature difference of 3 ° C. or more. When the temperature difference is 3 ° C., the belt having a length of 380 mm becomes 0.1 mm longer due to thermal expansion, and when the difference between the left and right becomes 0.1 mm, the belt shift becomes clear. When there is one temperature sensor, depending on the configuration of the image forming apparatus, if there is a temperature rise of 5 ° C or higher, the temperature difference between the left and right may be 3 ° C or higher. Move the liquid circulation means or turn on the heater.

<Left and right temperature detection>
As a sixth embodiment, a case where temperature sensors are provided on the left and right will be described. If the temperature sensors 38 and 39 are provided on the left and right as shown in FIG. 9, the temperature difference can be known directly, and the above-described control can be moved effectively. Also, depending on changes in the operating state of the image forming apparatus, the temperature distribution on the left and right may be reversed. In that case, the temperature difference is further reduced by changing the rotation direction of the fan, changing the heating location of the heater, be able to. Furthermore, the temperature distribution can be optimized by providing a plurality of temperature sensors.

  The image forming apparatus shown in the above embodiment is not limited to a four-rotation color laser printer or copying machine, and can be applied to an image forming apparatus using a belt-like image carrier including a tandem method.

  As the temperature adjusting means, a cooling device such as a cooler or other heat exchange means may be used in addition to the fan, the fluid container, and the heater.

  By using the embodiment of the present invention, it is possible to reduce the temperature difference between the left and right generated in the image forming apparatus and to reduce the shift phenomenon that occurs in a belt such as a transfer belt or a photosensitive belt. As a result, damage to the belt and uneven rotation of the belt can be eliminated, and a long-life and high-quality image forming apparatus can be provided.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is explanatory drawing at the time of providing a fan on the transfer belt which concerns on the Example of this invention. It is explanatory drawing at the time of providing a fan under the transfer belt which concerns on the Example of this invention. It is explanatory drawing at the time of providing a fan beside the transfer belt which concerns on the Example of this invention. It is explanatory drawing at the time of providing the fluid container beside the transfer belt which concerns on the Example of this invention. It is explanatory drawing at the time of providing a fluid container by the side of the transfer belt which concerns on the Example of this invention, and providing the circulation pump side by side. It is explanatory drawing at the time of providing a heating means under the transfer belt which concerns on the Example of this invention. It is explanatory drawing of the specific example which shows the belt periphery and the shift | offset | difference of a belt. It is explanatory drawing at the time of providing two temperature sensors which concern on the Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive body 2 ... Charger 3 ... Optical unit 4 ... Developing device 5 ... Intermediate transfer body 8 ... Paper feed cassette 9 ... Paper feed roller 10 ... Transfer roller 11 ... Fixing device 12 ... Transfer cleaner 13 ... Temperature sensor 14 ... Calculation Means 15 ... air conditioner 16 ... motor (encoder)

Claims (5)

  An image forming apparatus having a belt-like image carrier, wherein the image forming apparatus further comprises a temperature adjusting unit adjacent to the belt-like image carrier in the image forming apparatus.   2. The image forming apparatus according to claim 1, wherein the temperature adjusting means is an air conditioner.   The image forming apparatus according to claim 1, wherein the temperature adjusting unit is a fluid and a container for storing the fluid.   2. The image forming apparatus according to claim 1, wherein the temperature adjusting means is a heating means.   5. The image forming apparatus according to claim 1, further comprising at least one temperature detecting unit adjacent to a belt-like image carrier in the image forming apparatus.

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