JPH07271256A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of surely cleaning the excess toner sticking on the rear side of a transfer paper, even at the time of forming the image on the both side of the transfer paper, without staining the transfer paper in spreading the toner rubbed between the mutual feeding transfer papers or between the transfer paper and the feeding roller and obtaining the excellent image quality. CONSTITUTION:This image forming device is provided with the transferring part 4 for transferring the toner image formed on the image carrier 2 to the transfer paper, the fixing part 6 for fixing the toner image on the transfer paper, the cleaning part 7 for removing the toner stuck on the rear of the transfer paper. Further, the cleaning part 7 is equipped with the cleaning brush for removing the sticking toner while coming in contact with the rear of the transfer paper allowed to pass through the fixing part 6 and the pressing member disposed in the position opposite to the transfer paper across its transporting path, the cleaning brush provided with the linear notched part on a part of the cylinder is rotated in a state of repeating the pressing and the releasing between the pressing member.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a transfer portion having a transfer member for bringing the transfer paper into contact with an image carrier from the back side of the transfer paper, and transferring the toner image formed on the image carrier to the surface of the transfer paper, and the transfer paper. An image forming apparatus having a fixing unit for fixing the toner image on the transfer paper by heating the toner image from the front surface of the sheet, and a cleaning unit for cleaning the back surface of the transfer paper is disclosed in JP-A-63-83766. It is disclosed and publicly known.

[0003]

In the conventional image forming apparatus as described above, the cleaning section contacts the back surface of the transfer paper, and the cleaning belt contacts the surface of the cleaning belt and adheres to the cleaning belt. Although it is provided with a cleaning blade for removing the toner contained therein, the toner cannot be satisfactorily removed with such a cleaning blade. When images are formed on both sides of the transfer paper, an image is formed on the surface of the transfer paper at the fixing unit, the transfer paper is once stocked in the double-sided tray, and then fed again. During this first fixing, the fixing roller that heats the toner on the transfer paper comes into contact with the front surface of the transfer paper, and sufficient heat is not transferred to the toner adhering to the back surface of the transfer paper. When re-feeding such a transfer paper, the transfer paper is rubbed between the transfer papers or between the transfer paper and the paper feed roller to spread the toner, and thus the transfer paper is soiled and good image quality cannot be obtained. There's a problem.

Therefore, an object of the present invention is to solve the problems of the conventional image forming apparatus as described above, and even when images are formed on both sides of the transfer paper, the excess toner adhered to the back surface of the transfer paper is surely removed. When cleaning and re-feeding the transfer paper, there is no such thing as spreading the toner by rubbing between the transfer papers or between the transfer paper and the paper feed roller, and the transfer paper is not contaminated. An object is to provide an image forming apparatus that can obtain good image quality.

[0005]

In order to achieve the above-mentioned object, the invention of claim 1 has a transfer member for bringing the transfer paper into contact with the image carrier from the back surface of the transfer paper,
A transfer unit that transfers the toner image formed on the image carrier to the surface of the transfer paper, and a fixing unit that heats the toner image from the surface of the transfer paper to fix the toner image on the transfer paper,
In an image forming apparatus including a cleaning unit that removes the toner attached to the back surface of the transfer paper, the cleaning unit contacts the back surface of the transfer paper that has passed through the fixing unit and removes the toner attached to the back surface. The cleaning brush has a brush, a pressure member arranged at a position facing the cleaning brush across the transfer paper conveyance path, and a control means for controlling the rotation of the cleaning brush. It has a half-moon-shaped cross section having a notched cutout portion, and the control means rotates the cleaning brush to repeat a pressurized state and a non-pressurized state with the pressing member. is there. The invention of claim 2 is
According to the invention of claim 1, the cleaning brush is stopped at a position where the notch faces the pressure member and at a stop position rotated 180 degrees from the position. According to a third aspect of the invention, in the first aspect of the invention, the rotation speed of the cleaning brush changes according to the length of the transfer sheet to be cleaned in the transport direction. According to a fourth aspect of the invention, in the first aspect of the invention, the rotation speed of the cleaning brush changes according to a value in which the length of the transfer sheet to be cleaned in the conveyance direction is added to the transfer sheet interval. Is. Claim 5
The invention of claim 1 is characterized in that, in the invention of claim 1, when the image forming operation is started, the notch portion of the cleaning brush is placed at a position facing the pressing member. According to a sixth aspect of the invention, in the first aspect of the invention, the notch portion of the cleaning brush is placed at a position facing the pressing member at the time of initial processing immediately after the power is turned on.

[0006]

According to the first and second aspects of the present invention, when the main motor starts to operate,
When the cleaning brush is in the pressurizing position, the control circuit rotates the cleaning brush to the non-pressurizing position, and operates the operating section in the same manner as the conventional one,
When the double-sided mode is selected, image formation is started, and the transfer paper that has been fixed by the fixing unit is sent to the double-sided tray and reaches the cleaning unit, the control circuit rotates the cleaning brush and pressurizes the position. As a result, the toner adhered to the back surface of the transfer paper with a weak adhesive force because sufficient heat is not applied in the fixing section is easily removed by a cleaning brush that pressurizes the toner. After this, when the transfer paper passes through the cleaning section, the control circuit again rotates the cleaning brush 180 degrees to the non-pressurized position, keeps it until the next transfer paper arrives, and after reaching, does the same as above. , This will be repeated. According to a third aspect of the present invention, in the above configuration, the rotation speed of the cleaning brush is changed according to the length of the transfer sheet in the conveyance direction,
Perform cleaning using the entire arc of the cleaning brush. According to a fourth aspect of the present invention, when the transfer paper reaches the cleaning unit and the control unit rotates the cleaning brush, the rotation speed is the length in the transfer direction of the transfer paper and the transfer paper when the transfer paper is continuously copied. The rotation speed is changed according to the value obtained by adding the interval and the cleaning brush is moved when the leading edge of the next transfer paper reaches the contact portion between the cleaning brush and the pressure roller during continuous copying in this way. The cleaning brush and the pressure roller are brought into a non-pressurized state a little before that, and there is no obstacle for the leading edge of the transfer paper to be inserted. According to a fifth aspect of the present invention, when the image forming operation is started, and a sixth aspect of the invention is to place the notch portion of the cleaning brush at a position facing the pressing member at the time of initial processing immediately after turning on the power, and to perform the preceding image formation. Even if the cleaning brush stops and does not rotate to the non-pressurized position when the power is turned off and is left in the pressurized state, it is temporarily set to the non-pressurized position at the time of subsequent image formation. Do not interfere with the transfer paper conveyance by the cleaning unit.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of the present invention shown in FIGS. 1 to 3, FIG. 1 is an overall front view, in which this embodiment transfers the transfer paper from the back side of the transfer paper to the image carrier 2. A transfer unit 4 that has a transfer member 3 to be in contact with and transfers the toner image formed on the image carrier 2 to the surface of the transfer paper, and by heating the toner image from the surface of the transfer paper, the toner is transferred onto the transfer paper. The fixing unit 6 for fixing the image and the cleaning unit 7 for removing the toner adhering to the back surface of the transfer paper which has passed through the fixing unit 6 are provided. FIG. 2 shows details of the fixing unit 6, a part of the paper feeding unit, and the cleaning unit 7.
Reference numeral 9 denotes a fixing roller and a pressure roller of the fixing unit 6, and a cleaning unit 7 contacts a back surface of the transfer paper and removes a toner adhering to the back surface of the transfer paper 11 and a transfer paper conveyance path. Therefore, it has a pressure roller 12 arranged at a position facing the cleaning brush 11 and a transfer paper detection sensor 13.

As shown in FIG. 3, the cleaning brush 11 has a brush main body 14 having a substantially half-moon cross section by a notch 15 formed by linearly cutting a part of a cylinder, and its rotation. The shaft 17 is connected to the output shaft of the spring clutch 16, and when the spring clutch 16 is turned on for a certain time while the main motor (not shown) is rotating, the cleaning brush 11 is rotated in the opposite direction of the transfer paper by the rotation of the main motor. , Stops every 180 degrees. At this stop position, the notch 15 of the cleaning brush 11 is the pressure roller.
The position facing 12 and the position rotated 180 degrees from it. Further, a light shielding plate (not shown) is attached to the rotating shaft 17, and a cleaning brush home position sensor (hereinafter referred to as a brush HP sensor) using a general transmission type photo sensor is provided at a position corresponding to the light shielding plate. In this brush HP sensor, when the notch 15 of the cleaning brush 11 faces the pressure roller 12 and reaches the non-pressurized position, that is, the home position, the light is blocked by the light shielding plate to output the home position signal, and vice versa. A non-home position signal is output when the pressure position where the light is not blocked, that is, the non-home position position is reached.

When operating such an image forming apparatus, when a main motor (not shown) starts operating, a control circuit (not shown) confirms the output of the brush HP sensor,
When the cleaning brush 11 is in the pressure position, the spring clutch 16 is turned on for a certain period of time to
Rotate 11 to the non-pressurized position. In this way, the cleaning brush 11 is always in the non-pressurized position immediately after the rotation of the main motor.
This is to prevent the transfer paper from catching on the cleaning brush 11 and causing a jam or damaging the leading end of the transfer paper when it is inserted in the pressurizing position.

In such a state, by operating an operation unit (not shown) in the same manner as the conventional one, the double-sided mode is selected, image formation is started, and the fixing unit 6 finishes the fixing operation. By the action of the transfer path switching claw 21 in FIG. 2, the sheet is sent to the double-sided tray 18 and reaches the cleaning section 7. Here, the transfer paper detection sensor is passed through between the cleaning brush 11 and the pressure roller 12.
When it reaches 13, the transfer paper detection sensor 13 outputs the detection signal to the control circuit, whereby the control circuit turns on the spring clutch 16 for a certain period of time to rotate the cleaning brush 11 to the pressing position. As a result, the toner adhered to the back surface of the transfer paper with a weak adhesive force because sufficient heat is not applied in the fixing unit 6 is easily removed by the cleaning brush 11 that pressurizes the toner. After that, when the trailing edge of the transfer paper is detected by the transfer paper detection sensor 13, the output circuit causes the control circuit to turn on the spring clutch 16 again for a certain period of time to rotate the cleaning brush 11 180 degrees to the non-pressurized position. The process is kept as it is until the next transfer sheet arrives, and after the arrival, the same operation as described above is repeated and this is repeated.

FIG. 4 shows the essential parts of the cleaning section 7 used in the second and third embodiments of the present invention, and other parts are the same as those of the first embodiment and will not be described.
In this embodiment, a stepping motor 19 is used instead of the spring clutch 16 of the first embodiment. Mainly, only the points related to this difference will be explained. In such an image forming apparatus, when the main motor starts to operate in the same manner as in the first embodiment,
When the control circuit confirms the output of the brush HP sensor and the cleaning brush 11 is at the pressurizing position, the stepping motor 19 is rotated to rotate the cleaning brush 11 to the non-pressurizing position. When the transfer paper passes between the cleaning brush 11 and the pressure roller 12 of the cleaning unit 7 at such a position and reaches the transfer paper detection sensor 13, the control circuit in which the detection signal of the transfer paper detection sensor 13 is input. However, the stepping motor 19 is rotated to rotate the cleaning brush 11 to the pressing position. As a result, the toner attached to the back surface of the transfer paper is easily removed by the cleaning brush 11. After that, when the trailing edge of the transfer sheet is detected by the transfer sheet detection sensor 13, the control circuit again rotates the stepping motor 19 to rotate the cleaning brush 11 180 degrees to the non-pressurized position and reach the next transfer sheet. This is left as it is, and after reaching, the same operation as above is repeated, and this is repeated.

In the second embodiment, as described above, the rotation speed of the cleaning brush 11 is set to a speed corresponding to the length of the transfer paper in the conveying direction. As shown in FIG. The distance from the contact portion between the pressure roller 12 and the pressure roller 12 to the detection position of the transfer paper detection sensor 13 is 20 mm, the cleaning brush 11 is rotated from the non-pressure position to the pressure position,
Further, since the rotation angle from the pressing position to the non-pressing position is 315 degrees and the transfer speed of the transfer paper 1 is 120 mm / sec, the rotation speed of the cleaning brush 11 is

[Equation 1] Becomes With this, for example, A4 size (210 x 197 mm)
When the transfer paper 1 of FIG.
Has a length of 210 mm, and the number of rotations of the cleaning brush 11 is
The rotation speed is 0.55 rotations, and FIG. 6 shows the rotation speed of the cleaning brush 11 for each transfer paper size of this embodiment.

The radius of the arc of the cleaning brush 11 is 10 mm
Then, since the speed of the outer circumference of the arc portion is the speed of the outer circumference of the arc portion = 2πr × 1 second of rotation speed, even if the A4 size transfer paper 1 having the fastest rotation speed is laterally conveyed, it is 51.5 mm.
/ Sec, which is sufficiently slower than the transfer speed of the transfer paper 1 of 120 mm / sec,
The cleaning brush 11 can rub the back surface of the transfer paper 1 to easily remove the toner therefrom.

Further, as in a general copying machine, when the control circuit detects that the transfer sheet is jammed during the copying operation or the operation is abnormal during the copying operation, the transfer sheet is interrupted. At this time, if the cleaning brush 11 is rotating, the cleaning brush 11 and the pressure roller 12 are brought into a non-pressurized state and stopped when the cleaning brush 11 continues to rotate once.
This makes it possible to easily remove the transfer sheet that is stopped in the transport path.

Next, the difference between the third embodiment and the third embodiment will be described. As shown in FIG. 7, when the transfer paper 1 reaches the transfer paper detection sensor 13, the cleaning brush 11 is rotated. At this time, the rotation speed is set to the length of the transfer paper 1 in the conveyance direction. This is to set the rotation speed according to the value obtained by adding the transfer sheet interval when continuous copying is performed with the transfer sheet 1. By doing so, when the leading edge of the next transfer sheet 1 at the time of continuous copying reaches the contact portion between the cleaning brush 11 and the pressure roller 12, the cleaning brush 11 makes one full rotation and stops. The cleaning brush 11 and the pressure roller 12 are brought into a non-pressurized state slightly before that, which does not hinder the insertion of the leading end of the transfer paper 1.

The rotation speed of the cleaning brush 11 in this case is

[Equation 2] Becomes As a result, for example, when the A4 size transfer sheet 1 is conveyed in the lateral direction, the length of the transfer sheet 1 in the conveying direction is 210 mm.
The transfer paper interval is 270 mm, so cleaning brush 11
The number of rotations per second is 0.26, and the rotation speed of the cleaning brush 11 for each transfer sheet size of this embodiment is shown in FIG. 8. The length of the transfer sheet 1 is shorter than the A4 horizontal feed. However, since the value obtained by adding the length of the transfer sheet 1 and the transfer sheet interval is set to be the same as the A4 lateral feed, the rotation speed of the cleaning brush 11 is also the same.

In this way, the speed of the outer circumference of the arc portion is 16.3 mm / sec even in the case of A4 transverse feed, which is the fastest rotation,
The transfer speed of the transfer paper 1 is sufficiently slower than 120 mm / sec, and the back surface of the transfer paper 1 is rubbed with the cleaning brush 11 to easily remove the toner therefrom.

[0018]

The present invention is as described above, and the invention of claim 1 has a transfer member for bringing the transfer paper into contact with the image carrier from the back surface of the transfer paper, and is formed on the image carrier. A transfer unit that transfers the toner image to the front surface of the transfer paper, a fixing unit that fixes the toner image on the transfer paper by heating the toner image from the front surface of the transfer paper, and a toner that adheres to the back surface of the transfer paper is removed. The cleaning unit includes a cleaning unit, which contacts the back surface of the transfer paper that has passed through the fixing unit and removes toner adhering to the back surface, and a position facing the cleaning brush across the transfer paper transport path. And a control means for controlling the rotation of the cleaning brush, and the cleaning brush has a half-moon-shaped cross section having a notch formed by linearly cutting a part of a cylinder. The means rotates the cleaning brush and repeats a pressed state and a non-pressurized state between the cleaning brush and the pressing member. In the invention of claim 2, in the invention of claim 1, the cleaning brush is pressed at the notch portion. Since it stops at the position facing the member and the stop position rotated 180 degrees from that position, even when images are formed on both sides of the transfer paper, the excess toner adhering to the back surface of the transfer paper is surely cleaned,
Good image quality can be obtained without rubbing between the re-fed transfer papers or between the transfer papers and the paper feed roller to spread the toner and stain the transfer papers. The effect is that it can be made compact. According to the invention of claim 3, in the invention of claim 1, since the rotation speed of the cleaning brush changes according to the length of the transfer sheet to be cleaned in the conveyance direction, cleaning is performed using the entire arc portion of the cleaning brush. Therefore, there is an effect that the life of the cleaning brush can be extended. According to the invention of claim 4, in the invention of claim 1, the rotation speed of the cleaning brush changes depending on the value of the length of the transfer sheet to be cleaned in the conveying direction and the value of the transfer sheet interval. The speed can be reduced, the relative speed between the transfer paper and the cleaning brush can be increased, and the cleaning efficiency can be improved. Claim 5
In the invention of claim 1, in the invention of claim 1, when the image forming operation is started, the notch of the cleaning brush is placed at a position facing the pressing member, and in the invention of claim 6, in the invention of claim 1, the power is turned on. Immediately after the initial processing, the notch of the cleaning brush is placed at a position facing the pressure member,
Even if the cleaning brush stops and does not rotate to the home position due to an error such as the power being turned off during the preceding image formation and the cleaning brush is left under pressure, the cleaning part is transferred during the subsequent image formation. This has the effect of not obstructing the conveyance of paper.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a main part of a first embodiment of the present invention.

FIG. 2 is a front view of a fixing unit, a part of a paper feeding unit, and a cleaning unit of the above.

FIG. 3 is an enlarged perspective view of the above cleaning unit.

FIG. 4 is an enlarged perspective view of the cleaning unit according to the second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a state at the same time as A4 lateral feeding.

FIG. 6 is a rotation speed diagram of the cleaning brush for each transfer paper size.

FIG. 7 is an explanatory diagram showing a state at the time of A4 lateral feeding of the third embodiment of the present invention.

FIG. 8 is a rotation speed diagram of the cleaning brush for each transfer paper size.

[Explanation of symbols]

 1 transfer paper 2 image carrier 3 transfer member 4 transfer unit 6 fixing unit 7 cleaning unit 11 cleaning brush 12 pressure roller 13 transfer paper detection sensor 14 brush body 15 notch 16 spring clutch 17 rotating shaft 18 double-sided tray 19 stepping motor

Front page continuation (72) Inventor Keiichi Sanada 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Atsuro Tokunaga 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (6)

[Claims] 1. A transfer unit having a transfer member for bringing the transfer paper into contact with the image carrier from the back side of the transfer paper, and a transfer section for transferring the toner image formed on the image carrier to the surface of the transfer paper, In an image forming apparatus having a fixing unit for fixing the toner image on the transfer paper by heating the toner image from the front surface, and a cleaning unit for removing the toner adhering to the back surface of the transfer paper, the cleaning unit is the fixing unit. A cleaning brush that comes into contact with the back surface of the transfer paper that has passed through and removes the toner adhering to the back surface, and a pressure member that is disposed at a position facing the cleaning brush across the transfer paper transport path,
And a control means for controlling the rotation of the cleaning brush, wherein the cleaning brush has a half-moon shaped cross section having a notch formed by linearly cutting a part of a cylinder. An image forming apparatus characterized in that a pressure state and a non-pressure state are repeated between the pressure member and the pressure member. 2. The image forming apparatus according to claim 1, wherein the cleaning brush stops at a position where the notch portion faces the pressure member and at a stop position which is rotated 180 degrees from the position. 3. The image forming apparatus according to claim 1, wherein the rotation speed of the cleaning brush changes in accordance with the length of the transfer sheet to be cleaned in the conveyance direction. 4. The image forming apparatus according to claim 1, wherein the rotation speed of the cleaning brush changes in accordance with a value in which the length of the transfer sheet to be cleaned in the conveyance direction is added to the transfer sheet interval. 5. The image forming apparatus according to claim 1, wherein the notch portion of the cleaning brush is placed at a position facing the pressing member when the image forming operation is started. 6. The image forming apparatus according to claim 1, wherein the notch portion of the cleaning brush is placed at a position facing the pressing member at the time of initial processing immediately after the power is turned on.