JP2000330407A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease load caused by factors having adverse effect on the life of a fixing device, for example the realization of an offsetless, cleaningless, and oilless device by non-contact fixing, by having a mode whereby a heating means fixes toner without being in contact therewith and a mode whereby the heating means fixes toner in contact therewith. SOLUTION: In contact fixing, a movable roller 6 is pressed to a heating belt 1 by a movable-roller spring 7, and a carrying belt 2 is also pressed to the heating belt 1. Toner 9 on paper 8 being carried is preliminarily heated when passed through a gradually narrowing gap between the heating belt 1 and carrying belt 2 and is finally fused and fixed onto the paper 8 by the application of heat and pressure in the area where the heating belt 1 and carrying belt 2 are in contact with each other. When they are not in contact with each other, the pressing force of the movable-roller spring 7 is released, the carrying belt 2 consequently moves apart from the heating belt 1, and the toner 9 is heated and fused by heat transfer from the heating belt 1 via an air layer without being in contact therewith.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device applied to an image forming apparatus such as an electrophotographic recording device and a copying machine.

[0002]

2. Description of the Related Art In a fixing device of an electrophotographic recording apparatus,
As a conventional technique for mechanically changing the fixing conditions, for example, as described in JP-A-4-194967, there is a technique in which a fixing area is changed in accordance with a gloss mode and a non-gloss mode of an image. Further, as described in Japanese Patent Application Laid-Open No. 4-194968, there is a type in which the pressure to be applied is varied corresponding to the gloss mode and the non-gloss mode of an image.

[0003]

In the above-mentioned prior art, the heating means and the toner and the paper are always in pressure contact with each other in the portion where the toner is fixed, and when the fixing conditions are changed, only the range of the contact fixing is changed. . Therefore, there have been problems such as image deterioration called offset caused by contact fixing and occurrence of a short life of a cleaning mechanism for preventing offset. In addition, the range of gloss, non-glossy image quality, paper, and paper thickness that can be handled is also limited.

[0004]

The present invention has the following means to solve the above-mentioned problems.

(1) In a fixing device of an electrophotographic recording apparatus in which an unfixed toner on a recording sheet is heated by a heating unit and fixed on the recording sheet, a mode in which the heating unit performs fixing without contacting the toner, and a heating unit Has two fixing modes, a mode in which fixing is performed in a state of contact with the toner.

(2) In a fixing device of an electrophotographic recording apparatus in which an unfixed toner on a recording sheet is heated by a heating means and fixed on the recording sheet, each mode of contact fixing and non-contact fixing is arbitrarily selected.

(3) An unfixed toner on a recording sheet is heated by a heating means, and in a fixing device of an electrophotographic recording apparatus for fixing on a recording sheet, each mode of contact fixing and non-contact fixing is automatically selected.

(4) The fixing device described in (3) has means for detecting the recording paper thickness or the recording paper type.

(5) The fixing device described in (4) automatically selects the contact fixing mode and the non-contact fixing mode based on the result of detecting the recording paper thickness or the recording paper type.

(6) The fixing device described in (3) has means for detecting the toner color on the recording paper.

(7) The fixing device described in (6) automatically selects each of the contact fixing mode and the non-contact fixing mode based on the result of detecting the toner color.

[0012]

Embodiments of the present invention will be described below.

FIGS. 1A and 1B show a schematic configuration of a first embodiment of the present invention. FIG. 1A shows an operation of contact fixing, and FIG. 1B shows an operation of non-contact fixing. The heating belt 1 supported by a pair of heating belt supporting rollers 3 each having a halogen lamp 4 serving as a heat source therein is controlled at a certain temperature by turning on and off the halogen lamp 4. On the other hand, the transport belt 2 disposed so as to face the heating belt 1 is supported by a movable roller 6 and a transport belt support roller 5, and is in a state in which the movable belt spring 7 can press and contact the heating belt 1. Has become. The toner 9 that forms images and character information on the paper 8 is transported by the transport belt 2.

In the case of the contact fixing shown in FIG. 2A, the movable roller 6 is pressed against the heating belt 1 by the movable roller spring 7, and at the same time, the transport belt 2 is also pressed against the heating belt 1. Paper 8 transported by transport belt 2
The upper toner 9 is preheated when passing through the gap between the heating belt 1 and the conveyance belt 2 that gradually narrows from the paper supply side to the paper ejection side, and the heating belt 1 and the conveyance belt 2
Is finally heated and pressed at the contact portion, and is melted and fixed on the paper 8.

As described above, since the toner 9 is heated and pressurized and fixed after being brought into a semi-molten state by preheating, sufficient fixing strength can be obtained even at a low fixing temperature and a small pressure. In addition, in the final fixing section, sufficient heat can be applied to the toner 9 and the paper 8 because pressure and contact heating with high thermal efficiency are performed. Therefore, satisfactory fixing can be performed even when a large amount of heat is required for fixing, such as a color image or a thick paper with a large amount of toner adhesion. Further, since the contact fixing is performed, it is possible to add gloss to the image after fixing.

In the case of (B) non-contact fixing, the conveying belt 2 is separated from the heating belt 1 by releasing the pressing force of the movable roller spring 7, and a gap at a certain interval is formed between the heating belt 1 and the conveying belt 2. Formed between them. The paper 8 and the toner 9 are transported along the transport belt 2 so that a gap is maintained between the paper 8 and the toner 9 and the heating belt 1.
The toner 9 is heated and melted in a non-contact state by heat transfer from the heating belt 1 through the air layer. In the case of non-contact fixing, since the heating belt 1 serving as a heating unit does not contact the toner 9, image deterioration due to offset does not occur. Further, a cleaning mechanism and an oil application mechanism for preventing offset are not required, and the image after fixing becomes dull.

As described above, the mode of contact fixing and non-contact fixing can be selected by one fixing device, so that the range of image quality selection by gloss and matte can be widened, and various types of paper from thin paper to thick paper can be handled. Becomes possible. Further, it is possible to reduce the load due to factors that have adversely affected the life and reliability of the fixing device, such as realization of offsetless, cleaningless, and oilless by non-contact fixing.

Selection criteria for each of the contact fixing mode and the non-contact fixing mode include those that can be selected by the user with operation buttons, paper information (thick paper, thin paper, OHP, etc.) and toner in the electrophotographic recording apparatus. Information (monochrome, color) may be detected, and an optimum fixing mode may be automatically selected.

FIG. 2 shows another method of the contact fixing mode of the fixing device described with reference to FIG. 1, in which the position where the heating belt 1 and the conveying belt 2 come into contact with each other is on the paper feeding side, and FIG. The heating condition is different from the case where there is a contact position on the discharge side. As shown in FIG. 2, a sufficient fixing strength can be obtained by first applying pressure and heating and then gradually moving away from the heating means.

FIG. 3 shows an embodiment in which a cleaning roller 14 is attached to the fixing device according to the first embodiment of the present invention. When performing contact fixing as shown in FIG.
Since an offset may occur at the contact position between the heating belt 1 and the transport belt 2, the cleaning roller 14 is required to prevent image deterioration. The cleaning roller 14 is attached so as to be in contact with the surface of the heating belt 1, and is driven by the heating belt 1 or rotated with a certain speed difference from the peripheral speed of the heating belt 1 by a gear or the like. I have.

On the other hand, when non-contact fixing is performed as shown in FIG. 3B, the cleaning roller 14 is unnecessary because there is no offset, and the apparatus is in a standby state away from the heating belt 1. As described above, in the non-contact fixing mode, the cleaning life due to the occurrence of the offset and the heating belt 1
This is by far the most advantageous in terms of the reliability of the fixing device, which is a problem in contact fixing, such as surface damage.

Next, a second embodiment of the present invention will be described.

FIG. 4 shows a schematic configuration of the second embodiment.
Indicates an operation of contact fixing, and (B) indicates an operation of non-contact fixing. The heating belt 1 supported by the heating belt supporting roller 3 and the supporting roller 13 having the halogen lamp 4 serving as a heat source therein,
The temperature is controlled to a certain constant value by turning on and off the halogen lamp 4. A heating roller 10 having a halogen lamp 11 serving as a heat source is disposed on the paper discharge side, and the heating roller 10 has a structure that can be pressed against the transport belt 2 by a heating roller spring 12. . On the other hand, the transport belt 2 arranged to face the heating belt 1 is supported by a pair of transport belt support rollers 5. The toner 9 that forms image and character information on the paper 8 is transported by the transport belt 2 from the paper supply side to the paper discharge side.

In the case of the contact fixing shown in FIG. 1A, the paper 8 and the toner 9 conveyed by the conveyor belt 2 are preheated by the heating belt 1 arranged so as to face the conveyor belt 2. Then, the toner is pressed and heated by the heating roller 10 that is in pressure contact with the conveyor belt 2 by the heating roller spring 12, and fixing is performed.

In the case of (B) non-contact fixing, the pressing by the heating roller spring 12 is released and the heating roller 10 is released.
Is in a non-contact state with the paper 8 and the toner 9, and the fixing is performed only by the non-contact heating by the heating belt 1.

In the second embodiment of the present invention, since the positions of the heating belt 1 and the conveyor belt 2 are always fixed,
A complicated mechanism for moving each belt while applying tension so as not to sag is not required.

FIGS. 5A and 5B show the fixing device of FIG. 4 with the cleaning roller 14 attached thereto. As shown in FIG. 5, FIG. 5A shows the respective modes of contact fixing and FIG. 5B shows the respective modes of non-contact fixing. The cleaning roller 14 is attached so as to be in contact with the surface of the heating roller 10 as in FIG. 3, and is driven by the heating roller 10 or rotated at a certain speed difference from the peripheral speed of the heating roller 10 by a gear or the like. It is supposed to.

The fixing apparatus according to the present invention has been described above with reference to FIGS. 1 to 5. The respective modes of the contact fixing and the non-contact fixing can be optimally selected according to the image quality condition, paper condition and toner condition. In addition to obtaining a good image, the performance can be improved in terms of the life and reliability of the fixing device.

Referring to FIG. 6, one example of determination of each mode selection of contact fixing and non-contact fixing will be described.

In the contact fixing mode, generally, sufficient heat can be applied to toner and paper, and the toner has a function of crushing the toner by pressure. Therefore, a glossy image can be obtained in terms of image quality, and OHP paper or the like that requires toner permeability after fixing can be used in terms of paper type, and can be used for thick paper, color images with a large amount of toner attached, etc. Is also possible.

On the other hand, in the non-contact fixing mode, since fixing is performed only by heating, it can be applied to plain paper and thin paper, and to monochrome images with a small amount of toner adhesion. In terms of image quality, a matte image can be obtained. The greatest advantage of the non-contact fixing is that no offset is generated, so that the performance of the fixing device can be remarkably improved in terms of the life of the fixing device caused by the occurrence of the offset.

These are just examples of the judgment, and the user can freely select them according to his preference and judgment.

FIG. 7 shows a configuration example in which the fixing mode is automatically selected. The detecting means 14 detects the toner color before the paper 8 enters the fixing device, and determines the paper thickness and paper type. The mode is detected, and the fixing control device determines contact fixing and non-contact fixing, and switches to each mode. The position where the sheet 8 is detected may be a position immediately after the transfer, which is the previous process, if the toner color is detected, or a position immediately after the sheet feeding if the information regarding the sheet is detected.

Finally, the flow of contact / non-contact mode switching control and the operation of the fixing device will be described with reference to FIGS.

As shown in FIG. 8, first, selection of images such as color, monochrome, characters, etc., and selection of paper such as plain paper, thick paper, OHP, etc. are performed to determine contact or non-contact fixing. These image and paper selections can be performed by the user or automatically. After the selection of contact or non-contact is made, the switching cams 15 and 16 are operated to correspond to the respective fixing modes.

FIG. 9A shows a state of non-contact fixing, in which the space between the roller bearings 17 is expanded by the paper feed side cam 15 and the paper discharge side cam 16, and the heating belt 1 and the conveyance belt 2 are brought into a non-contact state. By maintaining the state, non-contact fixing becomes possible. on the other hand,
FIG. 9B shows the state of contact fixing, in which the movable roller 6 is moved by the rotation of the discharge cam 16 so that the movable roller spring 7 is moved.
As a result, the heating belt 1 and the conveyor belt 2 are brought into contact with each other, and contact fixing is enabled.

[0037]

The effects of the present invention are described below.

By making it possible to select the mode of contact fixing or non-contact fixing with a single fixing device, the range of image quality selection by gloss and matte can be widened, and it is possible to cope with various kinds of paper from thin paper to thick paper. Become. Further, it is possible to reduce the load due to factors that have adversely affected the life and reliability of the fixing device, such as realization of offsetless, cleaningless, and oilless by non-contact fixing. Therefore, the performance can be improved in terms of the life and reliability of the fixing device.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of a first embodiment of the present invention.

FIG. 2 is a diagram illustrating another method of contact fixing according to the first embodiment.

FIG. 3 is a diagram in which a cleaning roller is provided to the first embodiment.

FIG. 4 is a diagram showing a basic configuration of a second embodiment of the present invention.

FIG. 5 shows a second embodiment in which a cleaning roller is provided.

FIG. 6 shows an example of each fixing mode selection criterion.

FIG. 7 shows an example of a mounting position of the detecting means.

FIG. 8 shows an example of a fixing mode switching flow.

FIG. 9 illustrates the state of the apparatus in each fixing mode.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 heating belt 2 conveyance belt 3 heating belt support roller 4 halogen lamp 5 conveyance belt support roller 6 movable roller 7 movable roller spring 8 paper
9: toner, 10: heating roller, 11: halogen lamp, 12: heating roller spring, 13: supporting roller, 14 ...
Detecting means, 15: paper feed side cam, 16: paper discharge side cam, 17
... Roller bearings.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Goro Sato, 502, Kachimachi, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Inc. 2H033 AA10 AA48 BA11 BB17 BB34 BB35 BB38 BB39 CA39

Claims (1)

[Claims] 1. A fixing device of an electrophotographic recording apparatus, wherein an unfixed toner on a recording sheet is heated by a heating unit and is fixed on the recording sheet. A fixing device having two fixing modes, a mode in which fixing is performed in a state of contact with toner.