JPH0418585A - Image forming device - Google Patents

Abstract

PURPOSE:To accurately set the timings at which a cleaning member is brought into contact with a transfer drum and is separated therefrom while suppressing vibration and noise, etc., by providing a cleaning member displacing/driving means which separates and displaces the cleaning member from the peripheral surface of the transfer drum. CONSTITUTION:When a transfer sheet clamping member 4 comes near a cleaning position at the time of cleaning, the cleaning member displacing/driving cam 13 gradually pushes a cam follower 18. Consequently a cleaning device 9 is turned around a supporting shaft 12, and the cleaning member 8 is separated from the transfer drum 1. When the cam 13 passes, the cam follower 18 directly comes into contact with the transfer drum 1 again. Thus, a transfer sheet can be securely clamped without difficulty. Additionally the timings at which the cleaning member 8 is brought into contact with the transfer drum 1 and is separated therefrom can be accurately set, and the occurrences of vibration and noise, caused by the contact and separation can be suppressed.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to clamping the transfer paper around the circumference of the transfer drum while the end of the transfer paper is clamped by a transfer paper clamp member that can be opened and closed in the generatrix direction of the transfer drum. The present invention relates to an image forming apparatus that wraps a toner image around a surface and transfers a toner image formed on a latent image carrier to the wrapped transfer paper.

[Prior Art and Problems to be Solved by the Invention] In image forming apparatuses configured as electronic copiers, printers, 48 facsimile machines, etc., toner, paper powder, and other dust are deposited on the circumferential surface of the transfer drum. 5. During non-image formation, a cleaning member such as a brush or sponge is rotated in contact with the peripheral surface of the transfer drum at a predetermined relative speed difference, and the cleaning member rotating in contact removes the deposits. are doing.

When performing leaning in this manner, if the cleaning member remains in contact with the transfer drum, the cleaning member will also come into contact with the transfer paper clamp member when it passes through the member, which will prevent the transfer. Toner or the like gets into the paper clamp member, and the part of the transfer paper that is clamped becomes smeared with toner. Furthermore, if the transfer paper clamp member becomes clogged with toner, the transfer paper clamp member may malfunction.

In order to eliminate such problems, a configuration has been proposed in which the toner that has entered the gap between the transfer paper clamp members is removed by suction using a blower, but with this configuration,
It is difficult to sufficiently remove toner from the gaps.

Therefore, for example, a technique disclosed in Japanese Utility Model Application No. 159693/1983 and Japanese Patent Application No. 3342/1994 has been proposed in which the cleaning member is separated from the transfer drum when the transfer paper clamp member passes through. has been done.

By the way, in this type of image forming apparatus, the transfer paper is fed from a predetermined paper feeding section toward the transfer drum, and the leading edge of the paper is clamped by a transfer paper clamp member to wrap the transfer paper around the transfer drum. During the clamping process, when the transfer paper clamp member is released, or when the transfer paper is sent toward the released transfer paper clamp member faster than the linear speed of the transfer drum, slack may occur in the transfer paper. , the cleaning member must be kept far away from the transfer drum. That is, during image formation, in order to clamp the edges of the transfer paper, it is necessary to separate the cleaning member from the transfer drum by a gap greater than the amount of separation of the cleaning member during cleaning.

If the cleaning member is separated from the transfer drum by such a large gap during cleaning, for example, if the cleaning member is moved toward and away from the transfer drum using a solenoid, the suction stroke will become large. Therefore, there is a possibility that vibrations, noise, etc. may be generated, and the timing of contact and separation may be deviated, and cleaning before and after contact and separation may not be performed satisfactorily.

When this happens, the leading and trailing surfaces of the transfer paper become stained with toner.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that has a simple configuration and can accurately set the timing of contact and separation of a cleaning member with respect to a transfer drum while suppressing vibrations and noise.

[Means to solve the problem]

In order to achieve the above object, the present invention wraps the transfer paper around the peripheral surface of the transfer drum while clamping the end of the transfer paper with a transfer paper clamp member that can be opened and closed provided in the generatrix direction of the transfer drum. In an image forming apparatus configured to transfer a toner image formed on a latent image carrier onto a transfer paper, there is provided a cleaning member movable in a direction in which it comes into contact with a circumferential surface of a transfer drum and is brought into contact with the peripheral surface of the transfer drum; a drive source that rotationally drives the cleaning member when the cleaning member comes into contact with the peripheral surface of the transfer drum to clean the peripheral surface; a cleaning member displacement drive unit that periodically displaces the cleaning member away from the transfer drum each time the transfer drum rotates with a gap that allows passage of the closed transfer paper clamp member only when the image is formed; A cleaning member displacement drive means driven by the drive source to displace the cleaning member away from the transfer drum circumferential surface with a gap larger than the gap so that the transfer paper clamp member that opens and closes clamps the edge of the transfer paper. This paper proposes a configuration that includes the following.

〔Example〕

The present invention will be explained below based on one embodiment.

In FIG. 1, the transfer drum 1 has a belt-like connecting portion IA connected to annular portions on both sides.

A flexible support sheet 3 is wrapped around the transfer drum, and the wrapped sheet 3 substantially constitutes the peripheral surface of the transfer drum.

A transfer paper clamping member 4 is provided in the generatrix direction of the transfer drum 1, and the tip 4a of this member is movable, and when clamping the transfer paper, it is moved from the closed position as shown in FIG. It opens in a tilted position. After the leading edge of the transfer paper 5 fed from a predetermined paper feed section enters the transfer paper clamp member 4 in this state, the transfer paper clamp member 4 closes, the leading edge of the transfer paper is clamped, and the transfer paper is moved around the transfer drum. wrapped around the surface.

As shown in FIG. 4, the transfer drum 1 is brought into pressure contact with a drum-shaped photoreceptor 2, which is an example of a latent image carrier, and in this state, both are rotated in the directions of the arrows, and at this time, The toner image formed on the photoreceptor 2 is transferred onto the transfer paper wound around the transfer drum 1 by corona discharge of the transfer charger 6. For example, in the case of a color image forming apparatus, toner images of various colors are sequentially formed on the photoreceptor 2, and these images are superimposed and transferred onto a transfer paper on a transfer drum. After completing such transfer, the transfer paper is removed from the transfer drum 1, and then the transfer paper is removed from the transfer drum 1.

It passes through a fixing device (not shown) and is discharged to the outside of the machine.

The area surrounded by broken lines in FIG. 1 is the effective image forming area on the transfer paper.

In FIG. 1, the cleaning member 8 disposed parallel to the transfer drum 1 is composed of a circumferentially trimmed brush in this example, and is a unitized cleaning device ff19.
By swinging around a support shaft 12 fixed to the main body of the image forming apparatus, the cleaning device 9 can be freely displaced in the direction of coming into contact with and separating from the transfer drum 1. . In the cleaning device 9, a cleaning member 8 is attached to the transfer drum 1 by the elasticity of the tension spring 7.
The cleaning member 8 is in contact with the circumferential surface of the transfer drum 1 in this state, with the cleaning member 8 being in contact with the peripheral surface of the transfer drum 1. As the cleaning member, in addition to a brush, an appropriate member such as a sponge roller, a roller wrapped with cloth or other fibers, etc. can be used.

A cam 13 for driving the displacement of the cleaning member is provided on one annular portion of the transfer drum 1 at a position on the extension of the transfer paper clamp member 4 in the longitudinal direction. This cam 13 is
It may also be provided on the end surface of the transfer drum 1 so as to protrude beyond the circumferential surface of the drum 1.

On the other hand, a motor 14 which is a drive source for rotationally driving the cleaning member 8 is fixed to the cleaning device 9, and a gear 16 via a one-way clutch 17 and a gear 16 are mounted on the shaft 8A of the cleaning member 8. A cam follower 18, an auxiliary roller 19, etc. that are integrated with the shaft 8A are provided.

Further, a gear 23 via a one-way clutch 22 is provided on the shaft 21 supported by the cleaning device 9, and a cam 24 is further fixed to the end of the shaft. The cam 24 can be freely engaged with and disengaged from a cam follower 26 rotatably mounted on a side plate 25 of the main body of the image forming apparatus.

Here, during image formation, as shown in FIG. 4, the top portion of the longer diameter side of the cam 24 is in contact with the cam follower 26.
The cleaning device 9 is in a position that has been largely rotated to the right in the figure, and in this state, the cleaning member 8 is attached to the transfer drum 1.
far away from.

In such a situation, for example, the transfer paper clamping member 4, whose end portion of the transfer paper has already come off after the toner image transfer operation of the last image formation has been completed, is moved to a position of the cleaning member 8 (hereinafter, this position will be referred to as the cleaning position). 1), the motor 14 shown in FIG. 1 rotates in the direction of the broken line. Note that the motor 14 is also configured to rotate in the direction of the solid line, and hereinafter, rotation in this direction will be referred to as normal rotation, and rotation in the direction of the broken line will be referred to as reverse rotation.

When the motor 14 reverses in the direction of the broken line, the gear 23 that meshes with the gear 15 rotates, and at this time, the one-way clutch 2
2 transmits the rotation to the shaft 21.

This shaft 21 is rotated. Then, the cam 24 integrated with this shaft 21 rotates clockwise from the position shown in FIG.
rotates counterclockwise around the shaft 12, and the top of the short diameter side of the cam 24 is connected to the cam follower 26 as shown in FIGS.
When the cleaning device 9 comes into contact with the switch S1, the switch actuating protrusion 9A provided on the cleaning device 9 actuates the switch S1 and the motor 14
stop. That is, the cam 24 is moved 1/1 from the position shown in FIG.
After two rotations, the cam 24 stops at the position shown in FIG. 2, and at this time the cleaning member 8 comes into contact with the circumferential surface of the transfer drum 1 as shown in FIGS. 1 and 2. Note that when the motor 14 rotates in the direction of the dashed arrow, the gear 16 that meshes with the gear 15 rotates, but the one-way clutch 17 does not transmit the rotation to the shaft 8A, and the cleaning member 8 does not rotate.

In this state, a separate command causes the motor 14 in FIG. 1 to rotate in the normal rotation direction, that is, in the solid line direction opposite to the previous direction, and accordingly, the gear 16 that meshes with the gear 15 rotates. . At this time, the one-way clutch 17 transmits the rotation of the gear 16 to the shaft 8A to rotate the cleaning member 8 in the direction of the arrow as shown in FIG.

The transfer drum 1 is driven to rotate in the direction of the arrow as shown in FIG.
The direction in which the surface of cleaning member 8 moves is different from the direction in which the surface of cleaning member 8 moves. In this state, the cleaning member 8 cleans the surface of the transfer drum 1.

The cleaning member 8 indicated by the reference numeral 108 in FIG.
This is a collection roller that removes toner and the like attached to the member 8 from the member 8.

On the other hand, as the motor 14 rotates forward in the direction of the solid arrow, the gear 23 that meshes with the gear 15 rotates, but the one-way clutch 22 does not transmit the rotation to the shaft 21 and the cam 24 rotates.
remains stopped at the position shown in FIG.

By the way, as mentioned above, the cleaning member 8 comes into contact with the transfer drum 1 to perform cleaning, but during this cleaning, when the transfer paper clamp member 4 in FIG. 1 comes close to the cleaning position, the cleaning member The displacement cam 13 gradually pushes the cam follower 18 away, and the cleaning device 9 is rotated around the support shaft 12 to move the cleaning member 8 to the third position.
It is separated from the transfer drum 1 as shown in the figure. Then, when the cam 13 passes, the cam follower 18 comes into direct contact with the transfer drum 1 again.

When the cam 13 passes through the cam follower 18, the cleaning member 8 separates from the transfer drum 1. At this time, the distance δ is such that the closed transfer paper clamp member 4 (FIG. 1) moves away from the cleaning member 8. The gap is such that it does not hit the cleaning member 8 (for example, about 2 to 3 mm), and the closed transfer paper clamp member 4 should be the minimum gap that allows the transfer paper clamp member to pass through without hitting the cleaning member 8. desirable. Incidentally, the cam 13 always moves when the transfer paper clamp member 4 passes through the cleaning position.
The cleaning member 8 is arranged so that it does not come into contact with the transfer drum 1, and so that the cleaning member 8 comes into contact accurately from the tip side of the effective image forming area surrounded by the broken line on the transfer drum in FIG. The shape is determined.

During cleaning, the transfer drum 1 is rotated a predetermined number of times, and during this rotation, the separating operation of the cleaning member 8 is repeated every time the transfer paper clamp member 4 passes the cleaning position. It is.

The cam 13 is provided on the side of the transfer drum 1, and only when the transfer paper clamp member 4 passes through the cleaning position during cleaning, the cam 13 closes the cleaning member with a minimum gap δ□ that allows the closed transfer paper clamp member 4 to pass through. 8 can be said to constitute an example of the configuration of a displacement driving section of the cleaning member 8 that periodically displaces the cleaning member 8 apart each time the transfer drum 1 rotates.

As mentioned above, the cleaning operation for the transfer drum 1 is executed at a timely time that does not adversely affect the image formation.When the cleaning operation is completed, the motor 14 shown in FIG. The direction of the arrow is reversed. Then, the gear 23 meshing with the gear 15 rotates, and the one-way clutch 22 transmits the rotation to the shaft 21, causing the cam 24 to rotate clockwise from the position shown in FIG. 2. At this time, the cam 24
is relatively pushed away by the cam follower 26, the cleaning device [9 is rotated clockwise in the figure, and the cam 2
4 has rotated 172 turns to the position shown in FIG. 4, the switch actuating protrusion 9B actuates the switch S2, thereby stopping the motor 14. On the other hand, even though the motor 14 is reversed in the direction of the dashed arrow, the one-way clutch 17 does not transmit the rotation of the gear 16 to the shaft 8A, and the cleaning member 8 remains stopped.

Returning to the original explanation, as shown in FIG. 4, when the cam 24 is rotated to the position shown in the figure, the cleaning device 9 is rotated to the right to the maximum extent, and the cleaning member 8 is rotated at δ.
□ (FIG. 3) is separated from the transfer drum 1 by a distance of δ2, which is larger than the distance shown in FIG.

Here, when the cleaning is finished, the cleaning member 8 is separated by a large distance as described above, but after this,
If image formation is not performed, the cleaning member 8 remains largely separated from the transfer drum 1 and stands by.

When the image forming process is started in this manner,
The transfer drum 1 rotates in the direction of the arrow, and during this time the transfer paper clamp member 4 is opened in an inclined position as shown in the figure.

On the other hand, the transfer paper 5 is fed from a predetermined paper feed section toward the open transfer paper clamp member 4, and the leading edge of the transfer paper is clamped in the closed state. When the open transfer paper clamp member 4 passes through the cleaning position, if the cleaning member 8 is separated by a gap of δ□ (FIG. 3), there is a risk that the transfer paper clamp member 4 will collide with the cleaning member 8. This may stain the transfer paper clamp member 4 with toner.

Furthermore, in order to ensure that the leading edge of the transfer paper 5 is held in the transfer paper clamp member 4, the transfer paper is moved faster than the slow speed of the transfer drum 1.
After this leading edge enters the transfer paper clamp member 4, the transfer paper may become slack, and if this slack portion comes into contact with the cleaning member 8, the transfer paper will become stained with toner. In order to avoid such a problem, the cleaning member 8 must be separated from the transfer drum 1 by a distance of δ2, which is larger than δ. δ2 is a gap that does not cause any trouble when clamping the edge of the transfer paper. After all, when forming an image, it is necessary to ensure a gap between each sheet of paper so that it does not get in the way.

Conventionally, during cleaning, the cleaning member 8 was periodically separated from the transfer drum 1 by a distance δ2, but if such a separating operation was performed using a solenoid, the suction stroke would be large, causing vibrations. and noise.

Furthermore, the timing of the contact and separation of the cleaning member 8 may be out of order, and the back surface of the leading and trailing ends of the transfer paper may be stained with toner.

In this example, during cleaning, the separation amount of the cleaning member 8 is small, and moreover, the displacement drive unit of the leaning member, such as a cam 13 (FIG. 1) provided on the transfer drum, moves the cleaning member 8 to the transfer drum. Since they are spaced apart periodically for each rotation, generation of vibrations, noise, etc. can be suppressed. Furthermore, when using a solenoid, the output timing of the electrical signal system may be out of order, or the solenoid rise time may vary, but in this example, the cleaning member is transferred with accurate timing because it is directly driven by a cam. It can be brought into contact with and separated from the drum.

The large separation movement of the cleaning member 8 before and after the cleaning process is also performed by reversing the motor without using a solenoid or an electromagnetic clutch, so the structure is simple and noise and vibration are less likely to occur. Become.

In addition, in FIG. 1, gear 15. Gear 23° One-way clutch 22. Axis 21. Cam 24 and cam follower 2
6 and the like, when forming an image, a one gap δ is provided so that the edge of the transfer paper can be clamped by the transfer paper clamping member 4, which is opened and closed by being driven by a drive source such as the motor 14 (FIG. 3). This constitutes an example of a cleaning member displacement driving means for displacing the cleaning member 8 away from the peripheral surface of the transfer drum 1 with a larger gap δ2.

Note that FIG. 5 is an example of a timing chart corresponding to this embodiment, and in FIG. 1, the transfer drum home position is the position when the transfer paper clamp member 4 comes to the cleaning position.

〔Effect of the invention〕

As described above, according to the present invention, the transfer paper can be reliably clamped without any trouble, and the timing of the cleaning member approaching and separating from the transfer drum can be set accurately, so that cleaning failures occur before and after the cleaning member approaches and separates. It becomes difficult. Furthermore, it is possible to suppress the generation of vibrations and noises caused by the contact and separation, and a series of such functions can be achieved with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a contact/separation component of a cleaning member provided in an image forming apparatus according to an embodiment of the present invention, FIG. 2 is a front view of the main part thereof, and FIG. FIG. 4 is an operational view from FIG. 2 showing a state in which the cleaning member is separated from the transfer drum during image formation. FIG. 5 corresponds to the above embodiment. This is a timing chart. DESCRIPTION OF SYMBOLS 1... Transfer drum 2... Drum-shaped photoreceptor as a latent image carrier 4... Transfer paper clamp member 5... Transfer paper 8... Cleaning member 13... Displacement driving cam 14. ...Motor 24...Cam 26...Cam follower agent Norio Hoshino, patent attorney

Claims (1)

[Claims] The end of the transfer paper is clamped by a transfer paper clamp member provided in the generatrix direction of the transfer drum, which can be opened and closed, and the transfer paper is wrapped around the circumference of the transfer drum, and a latent image is formed on the wrapped transfer paper. An image forming apparatus configured to transfer a toner image formed on a carrier, comprising: a cleaning member movable in a direction of coming into contact with and separating from a circumferential surface of a transfer drum; a drive source for rotationally driving the cleaning member when cleaning the peripheral surface in contact with the transfer drum; and a drive source provided on the side of the transfer drum and closed only when the transfer paper clamp member passes through the area of the cleaning member during cleaning. a cleaning member displacement drive unit that periodically displaces the cleaning member away from the transfer drum each time the transfer drum rotates with a gap that allows the transfer paper clamp member to pass therethrough; and cleaning member displacement driving means for displacing the cleaning member away from the peripheral surface of the transfer drum with a gap larger than the gap so that the edge of the transfer paper is clamped by the transfer paper clamp member that opens and closes. An image forming apparatus equipped with the following.