JPH04296788A - Fixing device for electrophotographic copying device - Google Patents

Abstract

PURPOSE:To prevent the heat shielding efficiency of a shielding member and the heat efficiency of a heater from being deteriorated when a gap between the shielding member, which closes both end apertures of a heating roller and the heater, becomes large because of the variance of the common difference, etc., of the positioning of a supporting member supporting the heater or the like. CONSTITUTION:The cylindrical heating roller 35 is rotatably supported by a side plate 33 through a bearing 34. Besides, one end of a bracket 37 is fixed to the plate 33. Then, body ends of the heater 38 are fixedly supported by the other end of the bracket 37. The heater 38 is constituted by spreading a heat generating wire 40 in a glass tube 39 and provided by being passed through the center of the roller 35. Besides, both end parts of the tube 39 are press-fitted in the central hole 41a of a shielding plate 41 and the plate 34 is supported by the heater 38. Then, the plate 41 is made to abut on both end apertures 35a of the roller 35.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is applicable to electrophotographic devices such as laser printers, laser copying machines, and laser facsimiles.
The present invention can be applied to electrophotographic devices that record on sheets such as paper and envelopes using a method in which an image formed on a photoreceptor is transferred to a sheet for recording. Specifically, in such an electrophotographic device, a sheet after transfer is sandwiched between a heating roller and a pressure roller that rotate while pressing against each other, and heat and pressure are applied to the sheet while conveying it. The present invention relates to a fixing device that fixes a transferred image.

0002

BACKGROUND OF THE INVENTION In recent years, electrophotographic apparatuses have become smaller in response to user demands, but the internal temperature rises due to heat from the fixing device, which poses a problem that has an adverse effect on, for example, development in the electrophotographic process. be.

Therefore, conventionally, in this type of fixing device, a cylindrical heating roller 2 is rotatably supported on a side plate 1 via a bearing 3, as shown in FIG. One end of the support member 4 is supported at the other end, and the heating roller 2 is supported at the other end.
Both ends of the heater 5 passing through the center of the heating roller 2 are fixedly supported, and shielding members 6 are press-fitted into both ends of the heating roller 2 to close openings 2a at both ends of the heating roller 2 with the shielding members 6. There is something like that.

0004

By the way, it is desirable that the center hole 6a of the shielding member 6 be made as small as possible in terms of heat shielding efficiency. However, the support member 4
Heater 5 and heating roller due to positioning tolerance variations, etc.
If the center hole 6a of the shielding member 6 is too small, it will come into contact with the heater 5, causing friction when the heating roller 2 is driven, which will adversely affect the heater 5. There is. Therefore, the support member 4
In consideration of tolerance variations in positioning, etc., the center hole 6a had to be made considerably large. As a result, in the conventional fixing device, there is a problem that the gap between the heater 5 and the shielding member 6 becomes large, leading to large heat leakage, and the heat shielding efficiency of the shielding member 6 deteriorates, resulting in a decrease in the thermal efficiency of the heater 5. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to prevent the thermal efficiency of the heater from deteriorating due to the deterioration of the heat shielding efficiency of the shielding member.

[0006]

[Means for Solving the Problems] Therefore, the invention according to claim 1 provides, for example, as shown in the following illustrated embodiments,
A cylindrical heating roller 35 is rotatably supported, and a heater 38 passing through the center thereof is fixedly supported and transferred between the heating roller 35 and a pressure roller 42 that presses against the heating roller 35. In the fixing device 29 of the electrophotographic apparatus which pinches the subsequent sheet S and fixes the transferred image on the sheet S, shielding plates 41 that close the openings 35a at both ends of the heating roller 35 are pressed against both ends thereof. and is supported by the heater 38.

[0007] Furthermore, the invention according to claim 2 is characterized in that, in the invention according to claim 1, the shielding plate 41 is formed of a heat insulating material, as shown in the illustrated embodiment below, for example. .

[0008] Furthermore, the invention according to claim 3 is such that, in the invention according to claim 1, the heater 38 is constructed by extending a heating wire 40 in a glass tube 39, for example as shown in the illustrated embodiment below. The glass tube 39 is press-fitted into the center hole 41a of the shielding plate 41, and the shielding plate 41 is supported by the heater 38.

[0009]

[Function] In the invention according to claim 1, the heating roller
Even if the position of the heater 38 with respect to the roller 35 varies slightly,
The shield plate 41 continues to close the openings 35a at both ends of the heating roller 35.

Furthermore, in the second aspect of the invention, the shielding plate 41 made of a heat insulating material prevents heat radiation from the openings 35a at both ends of the heating roller 35.

Furthermore, in the invention as set forth in claim 3, the space between the shielding plate 41 and the heater 38 is maintained airtight.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic diagram showing the vicinity of a photoreceptor in a laser printer. Reference numeral 21 in the figure is a drum-shaped photoreceptor provided approximately at the center of the printer body. Around the photoreceptor 21, a charging device 22 and a developing device 2 are arranged clockwise.
3. A transfer device 24 and a cleaning device 25 are arranged, and an optical writing device 26 is arranged above the charging device 22.

Then, the sheet S is fed in the direction of arrow A and conveyed to the lower side of the photoreceptor 21 while being timed by the registration rollers 28. The photoconductor 21 is driven to rotate clockwise, and the charging device 22 uniformly charges the surface of the photoconductor 21. Then, the optical writing device 26 irradiates the laser beam L to create an electrostatic charge on the photoconductor 21. Form a latent image. After this electrostatic latent image is developed with toner in the developing device 23 to become a visible image, this visible image is transferred to the upper surface of the sheet S conveyed to the lower side of the photoreceptor 21 by a transfer device. Transfer at 24. The transferred sheet S passes through a fixing device 29 according to the present invention to fix the transferred image on the sheet. On the other hand, the surface of the photoreceptor 21 after the visible image has been transferred is cleaned by a cleaning device 25 . Then, the electrophotographic process described above is repeated again.

The fixing device 29 according to the present invention is constructed as shown in FIG. 1 in detail. That is, a cylindrical heating roller is connected to the pair of side plates 33 facing each other via bearings 34.
The roller 35 is rotatably provided.

Further, a bracket 37 is provided on the side plate 33.
Secure one end with a screw. The bracket 37 fixedly supports both ends of the heater 38 at its other end. Said heater 3
8 is constructed by extending a heating wire 40 within an elongated glass tube 39 and passing through the center of the heating roller 35. The heater 38 connects both ends of the glass tube 39 to shielding plates 41.
These shielding plates 41 are supported by being press-fitted into the center hole 41a of the shielding plate 41. These shielding plates 41 are made of a heat insulating elastic member such as silicone rubber or glass wool, and are formed slightly larger in diameter than the heating roller 35, and are pressed against both ends of the heating roller 35.

In the figure, reference numeral 42 denotes a pressure roller, which is rotatably supported via a bearing (not shown) and pressed against the heating roller 35 by being biased by an elastic member.

However, due to tolerance variations in the positioning of the bracket 37 that supports the heater 38, the heater 3
Even if the concentricity between the heating roller 35 and the heating roller 35 deviates, the shielding plate 41 slides on both end surfaces of the heating roller 35 and moves to the corrected position of the heater 38, so that the concentricity of the heating roller 35 continue to block. Then, when the laser printer is driven, in the fixing device 29, the heater 38 is energized and the heating roller 35 is heated.
At the same time, this heating roller 35 and the pressure roller 42 are both rotated.
The transferred image on the sheet S is fixed by applying heat and pressure while conveying the transferred sheet S by sandwiching the transfer image between the two rollers.

[0019]

Therefore, according to the present invention, even if the position of the heater with respect to the heating roller varies to some extent, the shielding plate continues to close the openings at both ends of the heating roller, so that the heating roller can be easily It is possible to maintain airtightness between the shielding plate and the heater and the shielding plate, prevent heat leakage from the heating roller, and improve the heat shielding efficiency of the shielding plate and the thermal efficiency of the heater.

According to the second aspect of the invention, heat radiation from the shielding plate is further prevented, so that the thermal efficiency of the heater can be further improved.

According to the third aspect of the invention, airtightness between the heater and the shielding plate can be easily maintained.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a fixing device that is an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing the vicinity of a photoreceptor of a laser printer including this fixing device.

FIG. 3 is a schematic configuration diagram of a conventional fixing device.

[Explanation of symbols]

29 Fixing device 35 Heating roller 35a Opening at both ends of heating roller 38 Heater 39 Glass tube 40 Heating wire 41 Shielding plate 41a Center hole of shielding plate 42 Pressure roller

Claims (3)

[Claims] Claim 1: A cylindrical heating roller is rotatably supported, a heater passing through the center of the heating roller is fixedly supported, and a pressure roller is pressed against the heating roller. In a fixing device of an electrophotographic apparatus that clamps a transferred sheet and fixes the transferred image on the sheet, shielding plates that close openings at both ends of the heating roller are pressed against both ends of the heating roller and supported by the heater. A fixing device for electrophotographic equipment. 2. The shielding plate is formed of a heat insulating material,
The fixing device for an electrophotographic apparatus according to claim 1. 3. The heater according to claim 1, wherein the heater is constructed by extending a heating wire in a glass tube, the glass tube is press-fitted into a center hole of the shielding plate, and the shielding plate is supported by the heater. A fixing device for the electrophotographic device described above.