JPH09160419A - Electrophotographic system printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and compact electrophotographic system printer by making use of pressure roll pressing/pressure releasing mechanisms originally provided in a fixing mechanism for an electrophotographic system printer for consecutive sheets for taking up a felt for cleaning heating roll. SOLUTION: The mechanisms for pressing a pressure roll and releasing pressure are constituted of pressure roll pressing/pressure releasing arms 8, pressure roll pressure releasing cams 9 and springs 10 and provided in both end parts of the pressure roll 2 one pair for each. The cams 9 are connected to a cam shaft 13 and rotated by a cam driving motor. A heating roll cleaning felt take-up arm 17 is installed on one end of a used cleaning felt take-up shaft 5, with a bearing 16 being rotatable only in a fixed direction. The arm 17 is abutted on the cam 9 provided on the cam shaft 13 and rocked by one rotation of the cam shaft 13 to take up the felt 4 on the shaft 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printing apparatus such as a laser beam printer provided with a heating and pressure roll type fixing device.

[0002]

2. Description of the Related Art As an electrophotographic printer, there is a printer in which a sheet on which toner is transferred is conveyed and fixed while being sandwiched between a heating roll and a pressure roll.

This method is excellent in many respects such as the size of the apparatus and high thermal efficiency, and is widely used.

Further, since it is excellent in adaptability to recycled paper or the like having a low surface smoothness and further to color toner, it is generally used in electrophotographic printers of any type.

By the way, in this method, the toner on the paper has a property of adhering to the heating roll side. For this reason,
Most of the electrophotographic printers equipped with a heating and pressure roll fixing device are equipped with a member for cleaning the toner adhering to the heating roll.

Further, in this method, the paper fixed by being sandwiched between the heating and pressure rolls has a property of being wound around the heating roll, and in order to prevent this, it is necessary to apply oil to the heating roll. . Generally, the heating roll cleaning member described above also has an oil application function.

The above-mentioned two properties tend to become remarkable as the printing speed, printing density and printing density increase. Further, in the electrophotographic printing apparatus for continuous paper, when the printing operation is stopped, the heating roll and the pressing roll that have sandwiched the paper until then are separated, and when the printing operation is restarted,
The paper is again nipped by the heating roll and the pressure roll, but at this time, the toner on the paper that has been fixed twice is in an excessively melted state (overfixed state), and a large amount of toner adheres to the heating roll. Shows the tendency to

Therefore, the heating roll cleaning mechanism in the above-described case requires a toner cleaning property and an excellent oil application amount, but is usually a cloth-like cleaning felt or cleaning paper. The cleaning felt or cleaning paper in the form of a roll is used while being wound up.

FIG. 2 is a perspective view of a toner fixing device having a heating roll cleaning mechanism, showing an example of a conventional electrophotographic printer.

The heating roll 1 and the pressure roll 2 are made of paper 3
It is arranged at a position facing each other with sandwiching.

The heating roll 1 is constructed to be rotatable by a support mechanism and a drive mechanism (not shown).

The pressure roll 2 is configured to press the paper 3 against the heating roll 1 at the time of printing and separate the paper 3 from the heating roll 1 at the time of non-printing by a pressure roll pressing / pressing release mechanism described below. There is.

The pressure roll pressing / pressing release mechanism comprises a pressure roll pressing / pressing release arm 8, a pressure roll pressing release cam 9 and a spring 10. There is one set each.

The arm 8 has a bearing 11 at one end and is rotatably supported by a frame (not shown). One end of the spring 10 is connected to the other end of the arm 8 and
Are pulled in the direction of the heating roll 1.

The pair of cams 9 are installed at positions where they come into contact with the cam followers 12 provided on the arm 8. And
The cam 9 is connected to a cam shaft 13, and the cam shaft 13 is rotatably supported by a frame (not shown) and can be rotated by a cam driving motor 14.

A rotatable shaft 15 projects from both ends of the pressure roll 2, and the shaft 15 is always in contact with a part of the arm 8.

At the time of non-printing, the camshaft 13 has the motor 1
By driving 4, the pressure roll 2 rotates so as to come to a position away from the heating roll 1, and then stops.

During printing, the cam shaft 13 further rotates from the non-printing state, the cam 9 separates from the cam follower 12, and the pressure roll 2 stops at a position where it is completely in contact with the heating roll 1. At this time, the spring 10 presses the pressure roll 2, the printing paper 3 is sandwiched between the pressure roll 2 and the heating roll 1, and the rotation of the heating roll 1 causes the pressure roll 2 to rotate.
Is driven, and the printing paper 3 is conveyed while being fixed.

The heating roll cleaning felt 4 has a cloth-like shape whose width is almost the same as that of the heating roll 1, one end of which is wound into a roll, and the other end of which is fixed to a used cleaning felt winding shaft 5. There is.

The shaft 5 is connected to a motor 6, and the felt 4 is wound around the shaft 5 by the rotation of the motor 6.

The felt pressing roll 7 includes the felt 4
Is pressed from the back surface thereof to press the felt 4 onto the heating roll 1.

The felt 4 is soaked with oil for improving the releasing property between the toner and the heating roll 1.

In the above structure, the toner on the paper 3 is melted by the heating roll 1 and fixed on the paper 3 by the pressure contact between the heating roll 1 and the pressure roll 2.
Part of the melted toner adheres to the heating roll 1. The toner attached on the heating roll 1 is cleaned by the felt 4. The felt 4 soiled with the toner is
Is wound around the shaft 5 by the rotation of.

In this way, the heating roll 1 is always kept clean and oil-coated.

The winding amount and the winding timing of the felt 4 are various, but roughly classified into the following two.

One is a method of always winding at a constant speed during a printing operation, and the other is a method of winding a certain amount when printing reaches a certain amount.

As described above, the amount of toner adhered to the heating roll 1 tends to be particularly large when the printing operation is restarted in the electrophotographic printing apparatus for continuous paper. Therefore, assuming such a case, conventionally, the winding amount of the felt 4 is set to be larger or the winding timing of the felt 4 is set to be earlier.
This means that it is extremely wasteful during continuous printing, and the running cost for printing increases.

By the way, in the conventional method, a power source such as a dedicated motor 6 or solenoid is required to wind up the felt 4, which increases the cost of the apparatus and
This is a factor that hinders downsizing of the device.

[0029]

According to the prior art, since the felt for cleaning the toner adhering to the heating roll is driven by a dedicated power, the cost of the device is increased and the size of the device is reduced. It was blocking.

An object of the present invention is to provide a heating roll cleaning mechanism capable of efficiently winding the felt without using a power dedicated to winding the felt, and to provide an inexpensive and small electrophotographic printer. It is in.

[0031]

[Means for Solving the Problems] The object is to utilize a pressure roll pressing / pressing release mechanism originally provided in a fixing mechanism of an electrophotographic printing apparatus for continuous paper to wind a felt for cleaning a heating roll. It is achieved by

Since the heating roll cleaning mechanism constructed as described above uses the power for pressing and releasing the pressing roll, it is for cleaning the heating roll when the pressing roll is pressed again where the toner is most likely to adhere to the heating roll. It is possible to wind up the felt and use a new felt surface. With this, the cleaning felt is automatically wound when the heating roller is most likely to be soiled, and an efficient winding operation is performed in which the felt is not wound when the heating roller is almost unstained, as in continuous printing, or The operation of winding at any time during printing can be easily achieved without using dedicated power.

[0033]

FIG. 1 shows an embodiment according to the present invention.

The heating roll 1 and the pressure roll 2 are the same as the paper 3
It is arranged at a position facing each other with sandwiching.

The heating roll 1 is rotatably constituted by a support mechanism and a drive mechanism (not shown).

The pressure roll 2 is configured to press the paper 3 against the heating roll 1 at the time of printing and separate the paper 3 from the heating roll 1 at the time of non-printing by a pressure roll pressing / pressing release mechanism described below. There is.

The pressure roll pressing / pressing release mechanism comprises a pressure roll pressing / pressing release arm 8, a pressure roll pressing release cam 9 and a spring 10. There is one set each.

The arm 8 has a bearing 11 at one end and is rotatably supported by a frame (not shown). One end of the spring 10 is connected to the other end of the arm 8 and
Are pulled in the direction of the heating roll 1.

The pair of cams 9 are installed at positions where they come into contact with the cam followers 12 provided on the arm 8. And
The cam 9 is connected to a cam shaft 13, and the cam shaft 13 is rotatably supported by a frame (not shown) and can be rotated by a cam driving motor 14.

A rotatable shaft 15 projects from both ends of the pressure roll 2, and the shaft 15 is always in contact with a part of the arm 8.

During non-printing, the camshaft 13 is connected to the motor 1
By driving 4, the pressure roll 2 rotates so as to come to a position away from the heating roll 1, and then stops.

During printing, the cam shaft 13 further rotates from the non-printing state, the cam 9 separates from the cam follower 12, and the pressure roll 2 stops at a position where it is completely in contact with the heating roll 1. At this time, the spring 10 presses the pressure roll 2, the printing paper 3 is sandwiched between the pressure roll 2 and the heating roll 1, and the rotation of the heating roll 1 causes the pressure roll 2 to rotate.
Is driven, and the printing paper 3 is conveyed while being fixed.

The heating roll cleaning felt 4 has a cloth-like shape whose width is almost the same as that of the heating roll 1, one end of which is wound into a roll and the other end of which is fixed to a used cleaning felt winding shaft 5. There is.

A heating roll cleaning felt winding arm 17 is installed at one end of the shaft 5 via a bearing 16 rotatable only in one direction. The arm 17 contacts the cam 9 provided on the cam shaft 13, One rotation of the cam shaft 13 causes the arm 17 to swing, and the felt 4 is wound around the shaft 5.

The felt pressing roll 7 presses the felt 4 from its back surface to press the felt 4 onto the heating roll 1.

The felt 4 is soaked with oil for improving the releasability between the toner and the heating roll 1.

In the above structure, the toner on the paper 3 is melted by the heating roll 1 and fixed on the paper 3 by the pressure contact between the heating roll 1 and the pressure roll 2.
Part of the melted toner adheres to the heating roll 1. The toner attached to the heating roll 1 is cleaned by the felt 4. The felt 4 soiled with the toner is
Is wound around the shaft 5 by the rotation of.

By the way, as described above, the amount of toner adhered to the heating roll 1 tends to be particularly large when the printing operation is restarted in the electrophotographic printing apparatus for continuous paper.

On the other hand, according to the present invention, without using a dedicated winding power for the felt 4 for cleaning the heating roll 1, the toner is most likely to adhere to the heating roll 1 when the printing operation is restarted, that is, the pressure is applied. When the roll 2 is pressed again, the felt 4 for cleaning the heating roll can be wound up and a new felt surface can be used.

If the arm 17 is brought into contact with the cam 9 provided on the cam shaft 13, the felt 4 can be wound even during continuous printing, that is, while the pressure roll 2 is pressed against the heating roll 1. It will be possible. In this case, the camshaft 13 may be reciprocated as many times as necessary for winding the felt 4 without rotating once. At this time, the cam 9 determines the phase so as not to come into contact with the cam follower 12. According to this configuration, the camshaft 13 makes one rotation during the operation from the printing stop to the reprinting,
The felt 4 is automatically wound, and the felt 4 can be wound at any timing during the printing operation, for example, when a certain specified amount is printed.

[0051]

According to the present invention, the cleaning felt is automatically wound when the heating roller is most likely to be soiled, and the felt is not wound when the heating roller is hardly soiled as in continuous printing. The typical winding operation,
Or even the action of winding at any point during printing,
It is easily achieved without the use of dedicated power.

In summary, according to the present invention, the pressure roll pressing / pressing release mechanism originally included in the fixing mechanism of the electrophotographic printing apparatus for continuous paper is used for winding the felt for cleaning the heating roll. Therefore, an inexpensive and small electrophotographic printing device can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a toner fixing device having a heating roll cleaning mechanism, showing an embodiment of an electrophotographic printing apparatus according to the present invention.

FIG. 2 is a perspective view of a toner fixing device having a heating roll cleaning mechanism, showing an example of a conventional electrophotographic printing apparatus.

[Explanation of symbols]

1 ... Heating roll, 2 ... Pressure roll, 3 ... Paper, 4 ... Heating roll cleaning felt, 5 ... Used cleaning felt take-up shaft, 7 ... Felt pressing roll, 8 ... Pressing roll pressing / pressing release Arm, 9 ... pressure roll pressing release cam, 12 ... cam follower, 13 ... cam shaft, 14 ... cam drive motor, 16 ... unidirectional rotatable bearing, 17 ... heating roll cleaning felt winding arm.

Front page continued (72) Inventor Haruyuki Honda 1060 Takeda, Hitachinaka City, Ibaraki, Hitachi Koki Co., Ltd. (72) Innovator Yoshinobu Gunji 1060 Takeda, Hitachinaka, Ibaraki Hitachi Koki Co., Ltd.

Claims (4)

[Claims] 1. A fixing mechanism comprising a heating roll, a pressure roll, and a pressure roll pressing / pressing release mechanism,
Further, in the electrophotographic printing apparatus including a heating roll cleaning mechanism including a heating roll cleaning felt, a pressure member for pressing the cleaning felt onto the heating roll, and a used cleaning felt winding shaft, A felt take-up arm for heating roll cleaning is provided at one end of the take-up shaft via a bearing that is rotatable only in one direction, and the felt take-up shaft is rotated by swinging the arm to take up the felt. An electrophotographic printing device characterized by the above. 2. The electrophotographic printing apparatus according to claim 1, wherein the arm is configured to swing by being connected to a power for pressing / releasing the pressing of the pressure roll. 3. The electrophotographic printing apparatus according to claim 2, wherein the arm swings in conjunction with a pressing / pressing-release operation of the pressure roll. 4. The electrophotographic printing apparatus according to claim 2, wherein the arm swings independently of a pressing / pressing-release operation of the pressure roll.