JPH04125583A - Heat fixing unit - Google Patents

Abstract

PURPOSE:To shorten the time of contacting between the surface of a heat roller and a separation claw and to suppress the generation of a flaw by separating the separation claw from the heat roller while a form detection sensor detects no form. CONSTITUTION:A form 14 which is conveyed as shown by an arrow (a) is detected by the form detection sensor 25. A microprocessor drives a solenoid 24 through a driving circuit 27 while no form is detected to lift a part 5a of the separation claw 5 as shown by an arrow d1, so the separation claw 5 rotates anticlockwise to a shaft 22, so that the separation claw 5 and heat roller 1 are put in a noncontact state. The integral contact time of contacting between the heat roller and separation claw is shortened to suppress the generation flaw of the surface of the heat roller.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat fixing device used in an electrophotographic recording device.

(Prior Art) Conventionally, in an electrophotographic recording device, a charged photosensitive drum is irradiated with a light source to form an electrostatic latent image on its surface, and toner is attached to the electrostatic latent image for development. After that, the toner image is transferred to a recording medium.

FIG. 2 is a sectional view of a conventional heat fixing device.

In the figure, the heat fixing device includes a heat roller 1 having a heater 12 made of a halogen lamp inside, a pressure roller 2 that is strongly pressed against the heat roller I by a spring system (not shown), and a pressure roller 2 that is pressed against the surface of the heat roller 10. a cleaning pad 3 for cleaning this; a cleaning roller 4 for cleaning the surface of the pressure roller 2;
A separating claw 5 for separating the paper 14 from the heat roller 1, transport guides 6 and 3 for guiding the running of the paper 14, a sensor 7 for detecting the surface temperature of the heat roller 1, and a cover 8. It consists of

The heat roller 1 is made of an aluminum vibrator 1b whose surface is coated with a heat-resistant mold release material 1a such as tetrafluoroethylene or perfluoroalkoxy. Further, the cleaning pad 3 and the cleaning roller 4 are made of heat-resistant felt, and are impregnated with an anti-offset liquid.

The paper 14 on which the toner image 13 has been transferred is advanced in the direction of arrow a by a transport roller (not shown), and is heated and pressed by a heat roller l rotating in the direction of arrow a and a pressure roller 2 rotating following the heat roller l. .

This fixes the toner onto the paper 14. after that,
The paper 14 is separated from the heat roller 1 by the separation claw 5 and discharged. Here, some of the toner adheres to the surface of the heat roller 1. The toner (offset toner) is cleaned by the cleaning pad 3, but some of it is transferred to the surface of the pressure roller 2. The toner that has migrated to the surface of the pressure roller 2 is brought into pressure contact with the pressure roller 2, and is scraped off and cleaned by the cleaning roller 4, which follows this and rotates in the direction of arrow C.

In such a heat fixing device, if the heat-resistant mold release material 1a coating the surface of the heat roller l is scratched by the separating claw 5 or the like and scratches occur, the fixing performance deteriorates at the scratched area and the print quality deteriorates. decreases.

(Problem B to be Solved by the Invention) However, in the conventional heat fixing device described above, the heat-resistant mold release material 1a coating the surface of the heat roller 1 is
The separating claws 5 are always in contact with each other, and the heat-resistant mold release material 1a is scratched by the separating claws 5 over time and scratches occur, resulting in deterioration of fixing properties and deterioration of the quality of the mark 1jl1 at the scratched portions.

The present invention solves the above problems of the conventional heat fixing device, reduces the contact time between the surface of the heat roller and the separating claw, suppresses the occurrence of scratches, and provides a heat fixing device with excellent printing quality. With the goal.

(Means for Solving the Problems) For this purpose, the heat fixing device of the present invention includes a heat roller that houses a heat source therein, and a pressure roller that presses and supports the heat roller, A separating claw is supported so as to be able to come into contact with and separate from the surface of the heat roller, and the paper conveyed between the heat roller and the pressure roller is separated by the separating claw.

Further, a paper detection sensor is provided to detect the presence or absence of paper being conveyed between the heat roller and the pressure roller, and when the paper is detected by the paper detection sensor, the separation claw is moved to the heat roller. If the separation claw is brought into contact with the heat roller and no paper is detected, the separation claw is separated from the heat roller.

(Function) According to the present invention, as described above, the heat roller housing a heat source therein and the pressure roller are disposed facing each other, and rotate in a state where both are pressed. Therefore, when paper with a toner image formed on its surface is conveyed between a heat roller and a pressure roller, pressure is applied by the pressure roller and at the same time it is heated by the heat roller, so the toner image is fixed on the paper. .

A separating claw is supported so as to be able to freely come into contact with and separate from the surface of the heat roller, and the paper conveyed between the heat roller and the pressure roller is discharged from between both rollers after the toner image is fixed. It is separated from the heat roller by a separation claw.

Further, a paper detection sensor is provided to detect the presence or absence of paper being conveyed between the heat roller and the pressure roller, and when the paper is detected by the paper detection sensor, the separation claw is moved to the heat roller. When brought into contact, the paper is separated, and if no paper is detected, the separation claw is separated from the heat roller.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a heat fixing device showing an embodiment of the present invention.

In the figure, 1 is a heat roller having a heater 12 made of a halogen lamp, 2 is a pressure roller that is strongly pressed against the heat roller 1 by a spring system (not shown),
3 is a cleaning pad that is pressed against the surface of the heat roller 1 to clean it, 4- is a cleaning roller for cleaning the surface of the pressure roller 2, and 5 is a separator for separating the paper from the heat roller 1. A claw, 6 is a conveyance guide for guiding the running of the paper, 7 is a sensor for detecting the surface temperature of the heat roller 1, and 8 is a cover.

The separation claw 5 is biased by a spring 21 and supported by a shaft 22. 24 is a solenoid, which moves up and down in the direction of arrow d in the figure. Here, a portion 5a of the separation claw 5 is arranged within the movable range of the solenoid 24. Also,
A paper detection sensor 25 is arranged at the paper inlet of the heat fixing device. Although a reflective optical sensor is used here as the paper detection sensor 25, a transmissive optical sensor may also be used. Further, a paper detection sensor for detecting a paper jam, which is already provided in the main body of the electrophotographic recording apparatus, may also be used.

FIG. 3 is a block diagram of a heat fixing device showing an embodiment of the present invention.

As shown in the figure, the paper detection sensor 25 is electrically coupled to a microprocessor (CPU) 26 having an I10 board inside. In addition, the solenoid 24 is connected to the drive circuit 27.
The drive circuit 27 is electrically coupled to the microprocessor 26 as well as the paper detection sensor 25.

In the heat fixing device configured as described above, the paper 14 conveyed in the direction of arrow a (FIG. 1) is detected by the paper detection sensor 25. The microprocessor 26 drives the solenoid 24 via the drive circuit 27 based on the detection result of the paper detection sensor 25 .

FIG. 4 is a solenoid drive time chart of the heat fixing device of the present invention.

As shown in the figure, when there is no paper 14, the solenoid 2
4 is driven and the paper 14 is present, the solenoid 24
is not driven.

FIG. 5 is a state diagram of the separation claw of the heat fixing device of the present invention.
) is a state diagram when the solenoid is driven, and FIG. 5(B) is a state diagram when the solenoid is not driven.

As shown in FIG. 5(A), the solenoid 24
In order to lift the part 5a in the direction of arrow d, the separation claw 5 rotates counterclockwise with respect to the shaft 22, and the separation claw 5 and the heat roller 1 are brought into a non-contact state. Conversely, if the solenoid 24 is not driven, the separation claw 5 is supported only by the spring 21 and the shaft 22, as shown in FIG. 5(B), so the separation claw 5 and the heat roller I are in contact.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

For example, in the above embodiment, the suction type solenoid 24
was used, but a repulsion type solenoid may also be used.

(Effects of the Invention) As described above in detail, according to the present invention, a paper detection sensor is provided to detect the presence or absence of paper conveyed between the heat roller and the pressure roller, and the paper detection sensor When a sheet is detected by the sensor, a separation claw is brought into contact with the heat roller to separate the paper, and when no paper is detected, the separation claw is separated from the heat roller.

Therefore, the cumulative contact time between the heat roller and the separating claw is reduced, the occurrence of scratches on the surface of the heat roller is suppressed, and a constant printing quality can always be maintained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a heat fixing device showing an embodiment of the present invention, and FIG.
3 is a block diagram of a heat fixing device according to an embodiment of the present invention. FIG. 4 is a solenoid drive time chart of the heat fixing device of the present invention. FIG. 5 is a sectional view of a conventional heat fixing device. FIG. 5(A) is a state diagram of the separating claw of the heat fixing device of the invention, FIG. 5(A) is a state diagram when the solenoid is driven, and FIG. 5(B) is a state diagram when the solenoid is not driven. 1... Heat roller, 2... Pressure roller, 3...
Cleaning pad, 4... Cleaning roller, 5.
...Separation claw, 24...Solenoid, 25...Paper detection sensor, 26...Microprocessor, 27...
drive circuit. Patent Applicant: Oki Electric Industry Co., Ltd. Agent, Patent Attorney: Makoto Kawai (2 others) Mami map Figure 2 Example of the ability of the present invention (showing meeting 1 of flat sleeping r)'Rotsu Figure 7 Time sheet Figure 4 z The present invention's n% foot vessel's meeting charge; Inushizono Figure 5

Claims (1)

[Claims] (a) a heat roller that houses a heat source therein; (b) a pressure roller that presses and supports the heat roller; (c) a pressure roller that can freely come into contact with and separate from the surface of the heat roller. (d) a separation claw for separating the paper that is supported and conveyed between the heat roller and the pressure roller; (d) a paper detector that detects the presence or absence of the paper that is conveyed between the heat roller and the pressure roller; and (e) means for bringing the separating claw into contact with the heat roller when the paper is detected by the paper detection sensor, and for separating the separating claw from the heat roller when no paper is detected. Heat fuser.