JP3497575B2 - Heat removal device in image forming apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer which is used in an image forming apparatus and is heated by a heat source such as a heating roller. The present invention relates to a heat exhaust device that efficiently sucks hot air to prevent adverse effects on other devices and components due to such heat and prevent heating of an outer wall of the device main body. 2. Description of the Related Art In an image forming apparatus of the type described above, a heat-fusible toner is used as an image forming material, and after forming an image composed of toner powder on a transfer material such as paper, This is heated and melted, and fixed on the transfer material. As such a heat source, a heating roller, a heat fixing belt or a fixed ceramic heater is preferably used. [0003] One of the problems in such an apparatus using a heat source is that the radiation heat from the heat source adversely affects other components and parts, and the use of the apparatus by heating the outer wall of the apparatus body near the heat source. Discomfort and safety issues
For this reason, conventionally, the periphery of the heat source or the periphery of the device including the heat source is surrounded by a heat insulating wall, so that heat radiation from the heat source to other parts is minimized. However, in an apparatus using a large-size transfer material, for example, a heating roller for fixing the transfer material also has a relatively large heat value. The efficiency of the exhaust heat is increased by forcibly sucking and exhausting the heated air around the heat source by a fan or a blower directly or through a duct or the like. Such air suction is conventionally performed only from one side of the heat source.For example, in the case of a heating roller, suction is performed from one direction orthogonal to the axis of the roller, but the efficiency of heat exhaust is poor, In addition, uniform air suction cannot be performed in the axial direction of the heat roller, and there is uneven heat removal in the axial direction (this is particularly remarkable when a long heating roller for fixing a large-sized transfer material is used). there were. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a heat exhaust device capable of efficiently discharging heat with a simple configuration. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a heat-dissipating device for an image forming apparatus having a heating roller, wherein the top plate of the apparatus including the heating roller and the image forming apparatus A shielding plate is provided so as to form at least two spaces vertically divided into two layers between the upper wall of the main body so as to extend in the longitudinal direction of the heating roller, and the two spaces are formed in the longitudinal direction. Intakes are respectively performed from different end portions, and the space further includes a partition inclined in the longitudinal direction so as to gradually reduce the space width toward an end portion opposite to the end portion on the intake side. A plate is provided, and a baffle plate which forms a gap in the inclined space with a wall defining the space and obstructs a part of the air flow due to the intake air flowing through the space is moved in the intake direction. That it was installed at an angle It is characterized by. [0009] As described above, by adopting a configuration in which the upper and lower two-layer spaces are respectively suctioned from different longitudinal sides,
Compared with the conventional configuration in which air is taken in only from one direction, uniform heat can be exhausted evenly in the longitudinal direction of the space.
Further, the above-mentioned partition plate and baffle plate effectively act to eliminate the gradient of the exhaust heat in the longitudinal direction during the intake. Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an example in which a heat removal device according to the present invention is incorporated in an electrophotographic copying machine. The illustrated copying machine has a fixing device 2 including a heating roller 1 as a heating source, and a heat discharging device according to the present invention is disposed above the fixing device 2 and operates as described later. The electrophotographic copying machine is roughly divided into a paper feeding unit 100 disposed below the apparatus, an image forming unit 200 disposed above the apparatus, and a document feed unit 300 disposed above the same. And a tray 400 for storing the transfer material. The paper feed unit 100 has two roll papers (transfer materials) 101 and 102 of different sizes loaded therein, and one of them is selected and pulled out according to a selection signal and cut into a predetermined length. , To the image forming unit 200. The image forming unit 200 includes a charger 202 disposed around the photosensitive drum 201, a short focus lens (for example, Selfoc)
203, developing device 204, transfer device 205, separating device 2
06, cleaning device 207 and eraser 208
including. These devices can adopt known configurations and operate in a known manner. The transfer material sent from the paper supply unit 100 is transferred with a toner image by the operation of the transfer device 205, and the transfer material carrying the unfixed toner image is separated from the photosensitive drum 201 by the separation device 206. Conveyor belt 209
To the heat fixing device 2. The fixing device 2 includes a heating roller 1 and a pressure roller 3 pressed against the heating roller 1,
The transfer material is sent to the nip between these rollers, and the interaction of heat and pressure fixes the toner image on the surface. The heating roller 1 is made of a metal roller having a surface formed with a layer having releasability from toner such as Teflon (trade name) on its surface, and has a built-in heater as a heat source in its hollow portion and / or its surroundings. The heating roller 1 has a close proximity to heat the surface of the heating roller 1 to a predetermined fixing temperature. Appropriate temperature control means controls such that the fixing temperature of the heating roller is maintained within a predetermined range value. On the other hand, the pressure roller 3 is made of an elastic roller such as silicon rubber, and is pressed against the outer periphery of the heating roller 1 by a biasing means such as a spring. If necessary, the pressure roller 3 together with the heating roller 1 can be similarly heated. The heat shield plate 4 serves as a top plate of the fixing device 2 so as to cover substantially the entire area above the fixing device 2 in order to suck and discharge the air above the heating device 2. Are located. The top plate 4 extends in a direction perpendicular to the paper surface of FIG. 1 at least over the length of the heating roller 1, and in the case of a conventional apparatus, between the top plate 4 and the upper wall 5 of the apparatus main body. As shown in the figure, an air flow that flows from left to right was formed to exhaust heat. However, as described above, it is not possible to sufficiently discharge heat when using a heat source having a large amount of heat radiation only by such means. In the present invention, as shown in FIG. 1, two spaces A and B are formed between the top plate 4 of the fixing device and the upper wall 5 of the device main body, at least vertically divided into two layers. Such a space is defined by a shielding plate 6 extending in a direction perpendicular to the plane of the drawing. Strictly speaking, the flow of air between the spaces A and B is not interrupted, and there is some air flow up and down from gaps around them. In the spaces A and B, air is sucked in from the back side in the direction perpendicular to the plane of the drawing for A and from the near side in the direction perpendicular to the plane of the drawing for B. A suction device such as a suitable blower or a fan is disposed at an appropriate position in the device main body, and a duct is provided so as to connect the suction device with the spaces A and B. As described above, by suctioning the upper and lower spaces in the two layers from opposite directions, it is possible to eliminate the unevenness of the exhaust heat in the longitudinal direction due to the suction from one direction as in the related art. In addition, the exhaust heat unevenness is, for example, at the upper wall of the device, one end in the longitudinal direction is cooled,
This refers to a state where heating cannot be sufficiently prevented at a part of the upper wall of the apparatus, such as a state where the other end side is not sufficiently cooled and has heat. In order to more sufficiently eliminate the unevenness of the exhaust heat in the longitudinal direction, it is preferable that the space B (and / or A) has the structure shown in FIG. FIG. 2 is a diagram of the space B as viewed from above, and the space B is schematically shown in a box shape for convenience of explanation. As shown, the space B has a partition plate 7 inclined in the longitudinal direction so as to gradually reduce the space width toward an end opposite to the end A on the intake side connected to the intake device. In addition, one or a plurality of baffle plates 8 are provided in the inclined space so as to be inclined in the intake direction so as to obstruct a part of the air flow due to the intake in the direction of the end A.
The baffle plate 8 is separated from the left and right walls defining the space B as shown in the figure, and allows air to be sucked from a gap between them. The partition plate 7 and the baffle plate 8 each have a space B
Of the space B
Reduces the volume from the intake side to the back side,
Thus, even when the longitudinal length of the space is considerably long, air can be sucked from the back side and the near side with substantially the same efficiency. In the above example, the heating roller is shown as the heating and fixing device. However, the present invention can be applied to other known heating devices such as a heating belt and a fixed ceramic heater. As described above, according to the present invention, even a long heating roller for a large-sized transfer material having a relatively large heat radiation amount and a long length in the axial direction is heated by it. The surrounding hot air can be efficiently exhausted without causing unevenness in the exhaust heat in the axial direction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an example of an electrophotographic copying machine incorporating a heat exhaust device according to the present invention. FIG. 2 is a view showing a heat discharging device of the electrophotographic copying machine incorporated in FIG. 1; [Description of Signs] 1 Heating roller 2 Pressure roller 100 Paper feed unit 200 Image forming unit 300 Document feed unit 400 Tray

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Claims (1)

(57) [Claim 1] An image forming apparatus having a heating roller
Heat exhaust device that includes a heating roller and a top plate.
At least two layers up and down between the upper wall of the image forming apparatus main body
The two separated spaces are each in the longitudinal direction of the heating roller.
Provide a shielding plate so that it extends to
The two spaces are different from each other in the longitudinal direction.
The air is sucked in, and the space is opposite to the end on the suction side.
To gradually narrow the space width toward the end of the
With a partition plate inclined toward the longitudinal direction,
Between the wall defining the space in this inclined space
Air from the intake air forming a gap and flowing in the space
A baffle that obstructs part of the flow is installed at an angle in the intake direction.
A heat exhaust device in the image forming apparatus, wherein the heat is emitted .