JP2007279263A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive image forming apparatus which is expected to have efficient cooling effect by providing air circulation paths of a plurality of systems corresponding to temperatures of heat generated by the apparatus, and also suppressed in upsizing on the whole. <P>SOLUTION: The image forming apparatus has first and second air circulation paths 11 and 12 for circulating air flows in an apparatus main body; and the first air circulation path 11 is provided nearby a fixing device 9 to face it and the second air circulation path 12 is provided nearby, for example, developing devices 3 and 4 constituting an image formation part to face them. Heat of high temperature generated by the fixing device 9 circulates with the air flow through the first air circulation path 11 and heat of low temperature generated by the developing devices 3 and 4 circulates with the air flow through the second air circulation path 12. The low-temperature air and high-temperature air circulate individually to increase cooling effect and the low-temperature developing devices 3 and 4 are not thermally affected by the high-temperature fixing device 9 and need not be cooled by a second radiator 14 more than necessary. Consequently, upsizing of an electric fan 18 is avoided and effect of noise reduction can be expected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus (hereinafter simply referred to as an “image forming apparatus”) such as a copying machine, a printer, a facsimile machine, and a multifunction machine, and more specifically, heat generated in the apparatus main body by an air circulation system. The present invention relates to a heat dissipation mechanism that discharges outside the aircraft.

  An image forming apparatus that forms an image using electrophotographic technology includes a photosensitive drum that is an electrostatic latent image carrier that forms an image forming unit. The surface of the photosensitive drum is uniformly charged with a charging device by applying a charging bias voltage, and an original image is formed on the charged photosensitive drum surface by an optical system to form an electrostatic latent image. The formed electrostatic latent image is visualized as a toner image by a developer (toner) by a developing device and transferred onto a sheet such as recording paper. The image transferred onto the sheet is fixed by heating or pressing with a fixing device, and then discharged onto a paper discharge tray or the like.

  By the way, due to the heat generated from the fixing device or the like, the internal temperature of the apparatus main body rises when the operation is continued for a long time. Excessive temperature rise affects the performance and functions of the equipment and also affects the usage environment, so cooling is necessary. Conventionally, internal air whose temperature has risen has been discharged from the exhaust port to the outside of the device body in order to cool and lower the internal temperature of the device body, but there was a problem that the exhaust sound generated at the exhaust port became noise . In addition, exhausting the gas and dust contained in the exhaust outside the aircraft will worsen the operating environment. In order to prevent this, when a filter is provided at the exhaust port, if a high mesh filter is used to enhance the gas adsorbing ability and dust collecting ability, air flow pressure loss will be caused.

  In order to solve the problems related to heat dissipation and exhaust as described above, an air flow (air flow) is generated by circulating air inside the apparatus main body, and a cooling effect is enhanced by a heat exchanger. Has been proposed (see, for example, Patent Document 1). In addition, an image forming apparatus has been proposed in which the airtightness of the apparatus main body is increased to form an air flow, and the cooling effect is enhanced by a heat exchange unit (see, for example, Patent Document 2).

JP-A-9-197946 JP 7-168487 A

  However, the techniques disclosed in Patent Documents 1 and 2 do not solve the following problem.

  The temperature of heat generated from the fixing device is higher than, for example, the temperature of heat generated from the developing device among the devices constituting the image forming unit. Depending on the equipment, the temperature rises further under the influence of the heat generated by itself or from other equipment, which degrades the performance of the equipment, so that the function can be maintained until the temperature rises. There is a temperature range. Due to the temperature difference between the heat generated in the fixing device and the developing device, the allowable temperature range is higher in the fixing device than in the developing device. Therefore, as in Patent Documents 1 and 2 described above, it is inefficient and the effect is halved if the fixing device and the developing device having a difference in allowable temperature are arranged and cooled in one system air circulation path. In other words, if an air flow raised in temperature by the high heat generated from the fixing device is circulated, the high-temperature air flow also passes in front of the developing device, so that the developing device is lowered to an allowable temperature to be cooled. Then, a great load due to heat dissipation will be applied. Momentarily, increasing the performance of the fan of the heat dissipation means or increasing the size of the fan will increase the cost.

  As described above, the object of the present invention is to provide an efficient cooling effect by providing a plurality of air circulation paths according to the temperature of heat generated from the equipment, and suppress the increase in the size of the entire apparatus and a low-cost image. It is to provide a forming apparatus.

  In order to achieve the above object, the image forming apparatus of the present invention includes an image forming unit that forms an image on a sheet in a main body of the image forming apparatus and a fixing device that heats and fixes the formed image. In addition, a plurality of air circulation paths for circulating an air flow are provided inside the image forming apparatus main body, and the one air circulation path provided in the vicinity facing the fixing device is isolated from other air circulation paths. The heat included in each air flow in the air circulation path is released to the outside of the image forming apparatus main body by a heat dissipating means.

  According to the heat dissipation mechanism of the image forming apparatus according to the present invention, there is a difference between the temperature of heat generated from, for example, the developing device constituting the image forming unit and the temperature of heat generated from the fixing device. A plurality of air circulation paths are provided to generate an air flow for radiating and cooling. As a result, in a developing device having a low generated heat temperature, cooling by unnecessary heat dissipation is unnecessary without being affected by the air flow from the fixing device having a high generated heat temperature. It is not necessary to upgrade the function of the fan, and the enlargement of the fan can be avoided. If the size of the fan is reduced, the effect of noise reduction can be expected.

  Hereinafter, a preferred embodiment of a heat dissipation mechanism of an image forming apparatus according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIG. 1, the image forming apparatus according to the present embodiment uses a laser scanner 1 that is a light source device based on image information sent from an external device such as an image reading device or a personal computer or a host device. A latent image of the image is formed on the surface of the photosensitive drum 2 which is an electrostatic latent image carrier. A charging bias voltage is applied to the drum surface, and in this case, a toner image is formed on the surface of the photosensitive drum 2 by developing with a developer (toner) using one of a plurality of developing units 3 and 4, and the image Is transferred to the intermediate transfer belt 5. At the time of forming a full color image, such a series of operations are sequentially repeated to superimpose images, thereby forming a full color image on the intermediate transfer belt 5. The formed full-color image is transferred to a sheet of recording paper that is selectively fed from the manual feed tray 6, the feeding cassette 7, and the paper feeding deck 8, and sent to the fixing device 9 for permanent fixing. After fixing, the sheet is discharged to the discharge tray 10.

  In such an image forming process, ozone is generated when the photosensitive drum 2 is charged by the charger, and heat is generated in the fixing device 9 when the image on the sheet is fixed. If these ozone and heat are left as they are in the main body of the apparatus, the operation and performance of peripheral devices will be adversely affected. In order to prevent this, in general, an electric fan is driven to rotate, ozone is guided to a filter, and heat is forcibly exhausted outside the apparatus main body.

  In FIG. 1, in order to exhaust generated heat outside the apparatus, a plurality of air flow (air flow) circulation paths are formed inside the apparatus main body. One of these air circulation paths is formed by a duct 16 that carries heat generated by the heat generated in the fixing device 9 (hereinafter referred to as “fixing heat” for convenience of explanation) while passing through the vicinity of the device while absorbing heat. The first air circulation path 11. The other air circulation path uses the heat of the image forming unit for forming a toner image on the recording material including the developing units 3 and 4 (hereinafter referred to as “heat of the image forming unit” for convenience of explanation). It is the 2nd air circulation path 12 formed with the duct 17 which carries and absorbs heat while passing the vicinity periphery. A first radiator 13 is disposed in the first air circulation path 11 to release “fixing heat” to the outside of the apparatus main body, and a second radiator 14 is disposed in the second air circulation path 12 to display “image”. The heat of the forming part "is released to the outside of the apparatus main body.

  By forming the first and second air circulation paths 11 and 12 with the ducts 16 and 17 in this way, the air flow including the fixing heat and the heat of the image forming unit is not mixed in the apparatus main body. Yes. In order to prevent air flow mixing, an air layer 15 is provided between the first radiator 13 and the second radiator 14 to isolate the two radiators from each other, and the first air circulation path 11 and the second air circulation path 12 are separated from each other. It prevents heat from being transferred from one side to the other. In order to further enhance the heat insulating effect, the air layer 15 can be isolated by a heat insulating material. In addition, a space is provided above the first and second radiators 13 and 14 to increase the efficiency of both radiators, and other devices and devices installed above are not devised. Suppose that only one radiator is installed for the first and second air circulation paths 11 and 12. In that case, the air flow is mixed in the one radiator, or the heat of the high temperature first air circulation path 11 is propagated to the low temperature second air circulation path 12 due to heat conduction in the radiator. As a result, there is a problem that a large load is applied to the radiator and the volume of the radiator is increased as in the prior art, or the electric fan installed in the radiator is increased in size, and the rotation speed is increased. In order to prevent this, first and second radiators 13 and 14 are arranged for each of the first and second air circulation paths 11 and 12.

  The radiators 13 and 14 will be described. Both the radiators 13 and 14 are aluminum rectangular fins having a high thermal conductivity. In the present embodiment, the radiator 13 through which a high-temperature air flow flows is made larger than the radiator 14 to enhance the heat radiation effect. In the present embodiment, the heat dissipation effect is changed depending on the size, but a configuration may be adopted in which a material is changed in addition to the size to provide a difference in the heat dissipation effect.

  Further, in the first air circulation path 11, an electric fan 18 is provided at an appropriate position of the duct 16 in order to enhance the circulation of the air flow. The electric fan 18 is installed at the rear lower side of the apparatus body of the duct 16 so that the fan rotation noise is not an issue and is effective for improving the environment. In addition, when an electric fan is provided in the 2nd air circulation path 12, it is the rear lower part side of an apparatus main body from the same viewpoint.

  Here, in the present embodiment, a heat insulating wall 19 that isolates the developing device 3 and the fixing device 9 is provided. Thereby, not only the air flow from one side to the other side between the developing device 3 and the fixing device 9 is blocked, but also the propagation of heat is mainly blocked. As the heat insulating wall 19, a material having low thermal conductivity can be used in order to reduce heat conduction inside the wall, and the heat insulating wall 19 is formed by covering the wall surface with a material having high reflectance in order to reduce radiation. It is.

  As shown in FIG. 2 which is a top view of the apparatus main body, the first and second air circulation paths 11 and 12 are provided with air filters 20 and 21 for removing gas and dust contained in the flowing air. Yes. Since the air flow passes through these air filters 20 and 21 several times, the function and material of the air filters 20 and 21 are selected with priority given to pressure loss over removal efficiency. As the air filter 20 of the first air circulation path 11, for example, a VOC (volatile organic compound) gas adsorption mainly made of activated carbon or a photocatalyst is used, and the air filter 21 of the second air circulation path 12 is, for example, Ozone adsorption catalysts mainly composed of ozone decomposition catalysts are used. However, such filter types are not particularly limited, and are suitable for each by utilizing the difference in the type and amount of gas and dust contained in the air flowing through the first and second air circulation paths 11 and 12. Can be selected.

  FIG. 3 shows the first air circulation path 11. Air flows into the space facing the fixing device 9 from the front side of the apparatus body through the duct 16, and heat or VOC emitted from the fixing device 9 or other devices while the air flow passes around the fixing device 9. Allow gas to be absorbed. That is, when the air flow passes through the air filter 20 for VOC gas as it is, a part of the VOC gas contained in the air flow is removed. Then, when passing through the first radiator 13, heat is released to the outside of the apparatus main body, and the airflow is cooled to an appropriate temperature. Since the electric fan 18 that forcibly causes an air flow to form an air flow is installed at the downstream side of the outlet of the first radiator 13 and below the rear portion of the apparatus main body, the air flow is sent directly to the front of the apparatus main body. It will be. The air flow circulates by repeating this process.

  The second air circulation path 12 functions in substantially the same manner, but differs from the first air circulation path 11 not in the vicinity of the fixing device 9 but through the space in the vicinity facing the developing devices 3 and 4. Adsorb ozone.

  From the above, the following effects are obtained in the first embodiment.

  1) The first air circulation path 11 is provided corresponding to the fixing device 9 that generates high heat, and the second air circulation path 12 is provided corresponding to the heat of the image forming unit that generates low heat. As a result, the developing devices 3 and 4 are not affected by the high-temperature air flow from the fixing device 9 and need not be cooled by heat radiation more than necessary. As a result, it is not necessary to upgrade the function of the electric fan 12, and an increase in the size of the fan can be avoided. If the size of the fan is reduced, the effect of noise reduction can be expected.

  2) Since the fixing device 9 having a high allowable temperature range is not cooled more than necessary, the energy efficiency of the fixing device 9 is improved.

  3) Since the air filter 20 arranged in the first air circulation path 11 and the air filter 21 arranged in the second air circulation path 12 can be selected by use and function, the degree of freedom in filter selection is increased. At the same time, the main factors indicating the filter performance of the air filters 20 and 21 are the reciprocal pressure loss and the removal efficiency, but the required removal efficiency is small and effective in reducing the pressure loss.

  4) By providing the heat insulating wall 19 between the fixing device 9 and the developing devices 3 and 4, it is possible to prevent both air flows in the first air circulation path 11 and the second air circulation path 12 from being mixed, It is possible to effectively prevent the heat released from the fixing device 9 from being propagated to the developing devices 3 and 4 by heat conduction or radiation action.

(Second Embodiment)
Next, a second embodiment will be described with reference to FIGS.

  The heat insulation wall in this 2nd Embodiment is a structural example which applied the said heat insulation wall 19 shown in 1st Embodiment. That is, the heat insulating wall in this case is composed of two layers: a heat transfer layer formed by the copper plate 19 a provided facing the developing devices 3 and 4 and a heat insulating layer formed by the vacuum heat insulating material 19 b provided facing the fixing device 9. It is formed as a laminated body. The heat transfer layer is not limited to the copper plate 19a, and aluminum or the like may be used. It is also possible to increase the apparent heat transfer rate through a heat pipe or the like inside. The copper plate 19a is connected to the radiating fins 24 serving as cooling means by heat pipes 23. The first and second radiators 13 and 14 can be shared as a cooling means. It is also possible to connect the copper plate 19 a to the cooling means 24 without using the heat pipe 23. On the other hand, the heat insulating layer is not limited to the vacuum heat insulating material 19b, and a resin or a foamed material can also be used.

  The arrows in FIG. 5 indicate main heat transfer paths 25. Most of the heat released from the fixing device 9 is blocked by the vacuum heat insulating material 19b of the heat insulating layer, and the heat pipe that is not completely cut off by the vacuum heat insulating material 19b passes through the copper plate 19a of the heat transfer layer to the heat pipe at the rear of the device main body. It moves to the connection part, moves to the cooling means 24 through the heat pipe 23, and is cooled by the cooling means 24. By configuring the separation wall 19 in such a manner, it is possible to further increase the effect of reducing the amount of heat transferred from the first air circulation path 11 to the second air circulation path 12 and reducing the load on the radiator.

  The first and second embodiments of the image forming apparatus according to the present invention have been described. However, the present invention is not limited to these embodiments, and other embodiments are possible as long as they do not depart from the gist of the present invention. Forms, applications, variations and combinations thereof are also possible.

1 is a perspective view showing a first embodiment of an image forming apparatus according to the present invention. 1 is a plan view showing an image forming apparatus according to a first embodiment. 1 is a side sectional view showing an image forming apparatus according to a first embodiment. FIG. 6 is a side view showing an image forming apparatus according to a second embodiment. FIG. 6 is a plan view showing an image forming apparatus according to a second embodiment.

Explanation of symbols

2 Photosensitive drums 3, 4 Developing device 9 Fixing device 11 First air circulation path 12 Second air circulation path 13 First heat radiator 14 Second heat radiator 15 Air layer 16, 17 Duct 18 Electric fan 19 Heat insulation wall 19a Copper plate ( Heat transfer layer)
19b Vacuum insulation (heat insulation layer)
20, 21 Air filter

Claims (8)

An image forming apparatus including an image forming unit that forms an image on a sheet in a main body of the image forming apparatus, and a fixing device that heats and fixes the formed image.
A plurality of air circulation paths for circulating an air flow are provided inside the image forming apparatus main body, and the one air circulation path provided in the vicinity facing the fixing device is isolated from other air circulation paths. The image forming apparatus is characterized in that heat contained in each air flow in the air circulation path is released to the outside of the image forming apparatus main body by a heat radiating means. The plurality of air circulation paths are
A first air circulation path for circulating the heat generated in the fixing device on the air flow in the image forming apparatus main body;
A second air circulation path for circulating heat in the image forming apparatus main body by placing heat generated in the image forming unit on an air flow;
And the heat dissipating means is
First heat radiating means for releasing heat of the air flow in the first air circulation path to the outside of the image forming apparatus main body;
A second heat dissipating means for releasing heat of the air flow in the second air circulation path to the outside of the image forming apparatus main body;
The image forming apparatus according to claim 1, wherein:   The image forming apparatus according to claim 1, wherein the image forming unit and the fixing device are separated from each other by a heat insulating wall to block heat transfer.   The image forming apparatus according to claim 2, wherein an air layer or a heat insulating layer is provided to isolate the first heat radiating unit from the second heat radiating unit.   The image forming apparatus according to claim 2, wherein an air filter is provided in each of the first and second air circulation paths.   6. The image according to claim 5, wherein the air filter provided in the first air circulation path is for VOC gas adsorption, and the air filter provided in the second air circulation path is ozone adsorption. Forming equipment.   The image forming apparatus according to claim 3, wherein the heat insulating wall is a laminated body of a heat transfer layer facing the image forming unit and a heat insulating layer facing the fixing device.   The image forming apparatus according to claim 7, further comprising a cooling unit for cooling the heat transfer layer.

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