JPH09305053A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device which securely peels paper and prevents damage to a heat roll. SOLUTION: A peeling baffle 50 disposed in contact with the surface of the heat roll 10 is composed of a first peeling baffle 50A disposed in a fixed position, and a second baffle 50 which moves between the position where it is in contact with the surface of the heat roll 10 and the position where it is apart from the heat roll 10. By constituting the second peeling baffle 50B in such a way as to be moved from the surface of the heat roll in the case of a small paper-size to prevent the direct contact of the baffle with the surface of the heat roll, the influence of the heat of the heat roll 10 is avoided and damage to the surface of the heat roll is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a toner image mounted on an electrophotographic machine, a facsimile, a printer or the like.

[0002]

2. Description of the Related Art A fixing device is equipped with a peeling claw for peeling a sheet from a fixing roll, and the peeling claw normally causes the tip of the peeling claw to contact a heat roll to peel the sheet. However, by constantly contacting the toes with the heat roll,
The inconvenience of scratching the surface of the heat roll occurred.

In order to solve this inconvenience, an abutting portion that comes into contact with the heating roll is provided outside the maximum paper passing area along the axial direction of the heating roll (heat roll), and between the heating roll and the peeling claw. A fixing device provided with a gap is disclosed in Japanese Patent Laid-Open No. 2-20.
It is disclosed in Japanese Patent No. 8679.

[0004]

Since the fixing device disclosed above fixes the separation baffle over the entire length of the heat roll, the peeling baffle stays close to the heat roll over the entire length even when a small size sheet passes. It exists and was affected by the heat of the heat roll at the separation baffle tip. Further, in the heat roll, heat is taken by the paper in the paper passing area and the temperature drops, but in the non-paper passing area, the temperature of the heat roll surface continues to rise. As a result, the tip portion of the peeling baffle arranged corresponding to the non-sheet passing area is deformed by heat, the peeling function of the paper is not fully executed, and paper jams and damage to the paper leading end portion are caused. It was the cause of the trouble. In particular, it has been a serious problem in an on-demand copying machine or printer having a small heat capacity. Therefore, the present invention is intended to improve the sheet peeling function in a fixing device capable of reliably peeling a sheet, particularly in a fixing device having a small heat capacity.

[0005]

A fixing device according to the present invention comprises a heat roll having a built-in heating unit, a pressure unit for bringing a transfer sheet into pressure contact with the heat roll, and a transfer sheet arranged side by side in the axial direction of the heat roll. Is provided with a peeling unit composed of a plurality of peeling units for peeling from the surface of the heat roll, and a control unit for outputting a control signal to the drive unit in response to a detection signal input from each sensor, and the tip of at least one peeling unit is a heat roll. And a movable peeling portion that moves to a position separated from the surface of the heat roll.

Further, the control means outputs a movable signal to the movable peeling section in response to a size detection signal of the transfer sheet, or the movable peeling section corresponds to a heat roll which becomes a non-sheet passing area when the transfer sheet has a small size. It is provided with a structure arranged at the position.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a structural explanatory diagram of a fixing device having a small heat capacity, and FIGS. 2 and 3 are structural explanatory diagrams of a peeling baffle. The fixing device 100 includes a heat roll 10 having a heating unit 15 therein, and a pressure roll 20 arranged in pressure contact with the heat roll 10. A temperature sensor 17 for detecting the surface temperature of the heat roll 10 is provided. The transfer sheet P on which the toner image is sent from the sheet guide 30 between the heat roll 10 and the pressure roll 20 is fixed by the heat and pressure while passing between the rolls. A peeling baffle 50 for peeling off the paper adhering to the surface of the heat roll 10 is provided in the vicinity of the paper feed path of the heat roll 10. The transfer paper P that moves while the toner image on the paper is fixed and adsorbed on the surface of the heat roll 10 is
By the tip portion of the peeling baffle 50, the heat roll 1
It is separated from the surface of No. 0, guided to the conveyance path 35, and discharged to the paper discharge tray by the discharge roll 40.

The peeling baffle 50 disposed along the axial direction of the heat roll 10 includes a first peeling baffle 50A having a longitudinal dimension of L ₁ and a longitudinal dimension of L _2.
And a second peeling baffle 50B. For example, if the longitudinal dimension of the heat roll 10 is A3 size, the dimension L ₁ of the first peeling baffle 50A is A4.
The short side size is set, and the dimension L _{2 in} the longitudinal direction of the second peeling baffle 50B is L ₂ = A3 short piece size−A4 short piece size,
And

First and second stripping baffles 50
(A, B) is a peeling portion 53 having a constant gap between the surface of the heat roll 10 and a supporting portion 55 that supports the peeling portion.
A plurality of protrusions 530 for guiding the sheet are provided on one surface of the peeling portion 53. The protrusions 530 are formed in a radial shape that is slightly inclined in the paper discharge direction. The first peeling baffle 50A of the peeling baffle 50 has a peeling portion 53.
The tip of the heat roller 10 surface and 0.2 ~ 0.5 mm
The support portion 55 is attached to the attachment portion 70 of the main body of the apparatus so as to be in a position having a gap.

Second strip baffle 5 of strip baffle 50
OB has a support portion 55 attached to a stud 75 fixed to an attachment portion 70 of the apparatus body via a spring 60. The peeling portion 53 of the second peeling baffle 50B is biased by the spring 60 and is in contact with the surface of the heat roll 10. The second peeling baffle 50B connects the connecting portion 57 to the solenoid 80. Then, when the solenoid 80 operates, the second peeling baffle 5 is connected through the connecting portion 57.
OB is a movable peeling portion that moves in the arrow X direction against the biasing force of the spring 60. Due to the movement of the support portion 55, the tip of the peeling portion 53 separates from the surface of the heat roll 10 and moves to a position having a certain gap.

The operation of the solenoid 80 is controlled by a controller (not shown). The control device controls the temperature of the heat roll 10 by the temperature detection signal from the temperature sensor 17, and outputs the operation signal of the solenoid 80 by the selected paper size detection signal.

Now, referring to FIG. 4, the temperature distribution between the paper passing area and the non-paper passing area of the heat roll 10 will be examined. In this graph, the vertical axis represents the surface temperature of the heat roll and the horizontal axis represents the position of the heat roll. The solid line represents the surface temperature of the heat roll 10 when the A4 size is continuously run in the on-demand type small heat capacity copying machine, and the chain temperature is the surface temperature of the heat roll 10 when the A4 size is continuously run in the normal type copying machine. It is represented by. According to this graph, in the copying machine having a small heat capacity shown by the solid line, the non-sheet passing area (between A4 and A3) was raised to 250 ° C. by continuous running of A4 size as compared with the ordinary copying machine.

Further, referring to FIG. 5, the surface temperature of the heat roll 10 and the distance between the heat roll 10 and the peeling portion 53 of the peeling baffle 50 are changed, and the influence on the peeling portion 53 is examined by the temperature of the peeling portion. Here, the heat resistant temperature of the peeling baffle 50 formed of PET is 180 ° C. A solid line shows a temperature change of the peeling portion 53 of the peeling baffle 50 of the on-demand type small heat capacity copying machine, and a broken line shows a temperature change of an ordinary copying machine. In an ordinary copying machine, the surface temperature of the heat roll is up to about 205 ° C.
The distance between the heat roll 10 and the heat roll 10 is 0.3 mm, which is the heat resistant temperature of the peeling baffle 50. However, in the case of an on-demand type small heat capacity copying machine, the surface temperature of the heat roll rises to 250 ° C. Even if the distance from the surface of the heat roll 10 is 0.5 mm, the heat resistant temperature of 180 ° C. is reached. Therefore, in the fixing device having a small heat capacity in this embodiment, when a small-sized sheet is continuously run, the peeling baffle arranged corresponding to the non-sheet passing area is a movable peeling baffle.

That is, in this embodiment, the second separation baffle 50B is constructed to be movable. When passing a large size sheet, the first peeling baffle 50 is used.
A and the second peeling baffle 50B both have the peeling section 53 arranged at a position in contact with the heat roll 10 and when passing a small size sheet, the solenoid 80 is operated to move the second peeling baffle 50B. Then, the peeling portion 53 is located at a position separated from the surface of the heat roll 10 by at least 0.5 mm or more. It takes about 30 seconds for the temperature of the non-sheet passing portion of the heat roll to drop to the normal temperature after the copying operation is completed. So, after the copy operation is over,
When 30 seconds have elapsed, the solenoid 80 is deactivated and the second peeling baffle 50B is moved to a position where the peeling section 53 has a predetermined gap from the surface of the heat roll 10.

Next, the control of the second peeling baffle 50B by the controller will be described with reference to the flow chart of FIG. When the power is turned on in step ST11 and the copy start is instructed in step ST12, it is determined in step ST13 whether or not the size of the used paper is small, that is, size A4 in this embodiment. This determination is based on a size detection signal from a size detection sensor provided on the manual feed tray or the cassette tray. When the paper size is large, shift to the normal copy operation and wait until the next copy start is instructed. When the size of the used paper is small, the process proceeds to step ST14 and the operation ON signal is output to the solenoid 80. When the solenoid 80 operates, the second peeling baffle 50B moves in the direction of arrow X,
The tip of the peeling portion 53 separates from the surface of the heat roll 10.
The copy operation is executed in this state. Step ST15
When it is determined that the elapsed time from the end of copying is 30 seconds, the operation OFF signal is output to the solenoid 80. The peeling baffle 50 returns the peeling portion 53 to the initial position in contact with the surface of the heat roll 10 by the urging force of the spring 60.

In this embodiment, the peeling baffle is composed of two peeling baffles, but the peeling baffle may be divided into a plurality of pieces if necessary.

[0017]

As described above, in the fixing device of this copying machine, a part of the peeling baffle is in contact with the heat roll,
It can be moved to a position away from the surface of the heat roll,
When small size sheets are continuously fed, the peeling baffle corresponding to the non-sheet passing portion is moved to a position where it is not affected by the temperature of the heat roll, so that thermal deformation of the tip of the peeling baffle and peeling portion Prevents paper jams and paper damage due to paper deformation. Furthermore, since the peeling baffle in the non-paper passing area does not directly contact the heat roll, the heat roll surface is not damaged.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a fixing device of the present invention.

FIG. 2 is a plan view illustrating a relationship between a heat roll and a peeling baffle.

FIG. 3 is a perspective view of a main part of the fixing device.

FIG. 4 is a graph showing a temperature change depending on a position of a heat roll.

FIG. 5 is a graph showing a temperature change due to a gap from a heat roll of a peeling baffle.

FIG. 6 is a flowchart of the control device.

[Explanation of symbols]

10 heat roll, 17 temperature sensor, 20 pressure roll, 50 peeling baffle, 50A 1st peeling baffle, 50B 2nd peeling baffle, 60 spring, 70 attaching part, 80 solenoid.

Claims (3)

[Claims] 1. A heat roll having a built-in heating unit, a pressurizing unit for pressing the transfer paper to the heat roll, a peeling unit for peeling the transfer paper on the surface of the heat roll, and a drive unit based on a detection signal input from each sensor. In the fixing device having a control unit for outputting a control signal to the heat roll, the peeling unit is composed of a plurality of peeling units arranged in parallel in the axial direction of the heat roll, and the tip of at least one peeling unit contacts the surface of the heat roll. A fixing device including a movable peeling unit that moves to a position in contact with the heat roll and a position separated from the surface of the heat roll. 2. The fixing device according to claim 1, wherein the control means outputs a movable signal to the movable peeling portion in response to a size detection signal of the transfer sheet. 3. The fixing device according to claim 1, wherein the movable peeling section is arranged at a position corresponding to a heat roll which is a non-sheet passing area when the transfer sheet has a small size.