JPH08160772A - Transfer device - Google Patents

Abstract

PURPOSE: To provide a transfer device constituted so that toner is prevented from being filmed on an image carrier or a transfer roller, an abnormal image is not formed and it can cope with highspeed transfer processing. CONSTITUTION: The transfer device is constituted of a photosensitive drum 1, the transfer roller 2 transferring a toner image on the drum 1 on a transfer paper 8, a cleaning roller 3 cleaning the toner on the roller 2, a blade 4 abutting on the roller 3 and scraping the toner transferred from the roller 2 from the roller 3 and a multipolarly magnetized magnetic plate for transmitting the rotational driving of the roller 3 to the roller 2. Besides, a driving means 11 changing the position of the roller 2 is constituted by rotatably supporting the roller 2 by one end of the arm 5 supported by a supporting shaft 12 so that it can be fluctuated and fitting a solenoid 6 to the other end. Then, the rotation speed of the roller 2 is driven at a higher speed than the speed of a transfer process time while the roller 2 is closely brought into contact with the roller 3.

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 a copying machine, a facsimile machine, a printer, etc., and more specifically, a toner provided on the image carrier so as to be movable toward and away from the image carrier. The present invention relates to a transfer device having a transfer roller for transferring an image onto a transfer sheet, a cleaning roller rotatable with respect to the transfer roller, and a blade that is in contact with the cleaning roller.

[0002]

[Prior art]

[Prior Art 1] Conventionally, as a transfer device of this type, as a means for preventing contamination of the transfer roller, a method of detecting the length of the transfer paper and separating the transfer roller from the image carrier (for example, (See Japanese Utility Model Publication No. 3-127351),
A method is known in which a blade is directly brought into contact with the transfer roller to clean the transfer roller. [Prior Art 2] In Japanese Patent Laid-Open No. 4-361284, a toner image formed on an image carrier is transferred onto the transfer paper by passing the transfer paper between the image carrier and the transfer roller. In the transfer device, a bias power source for transfer, a bias power source for cleaning transfer paper, and a high-speed drive unit that drives the transfer roller to rotate at a higher speed than during transfer are provided during non-transfer. There has been proposed a transfer device in which a power source is connected to the transfer roller, a bias power source for cleaning the transfer paper is connected to the transfer roller when the transfer is not performed, and the transfer roller is driven at a high speed by the high speed drive unit. [Prior Art 3] In Japanese Patent Laid-Open No. 4-263279, a cleaning member that can move in and out of contact with a transfer roller that can contact the image carrier is provided, and cleaning is performed at times other than the transfer step of the transfer roller. A transfer device has also been proposed in which a member is brought into contact with a transfer roller for cleaning.

[0003]

However, the prior art 1
According to the above configuration, even if the transfer roller is separated from the image carrier at a time other than the transfer step, if the size of the transfer paper is different, specifically, after transferring to a transfer paper having a relatively narrow width, In the case where transfer is performed on a transfer paper having a relatively wide width, there is a problem that toner stains occur on the back surface of the transfer paper having a relatively wide width. This is because the toner adheres to the transfer roller outside the transfer size during the preceding transfer process to the relatively narrow transfer paper, and this is transferred to the transfer position next to the relatively wide transfer paper. It is caused by soiling the back side of the. Further, in the case where the transfer roller is cleaned by directly contacting the blade with the transfer roller, the blade is worn due to friction and the toner filming in which the toner is fused and agglomerated due to the frictional heat with the transfer roller causes an abnormal image. There was a problem that it caused.

Further, according to the structure of the prior art 2, since the transfer roller is brought into contact with the image carrier and the rotational speed of the transfer roller is made higher than the rotational speed of the image carrier, the transfer roller and the image are transferred. There is a problem that toner filming is likely to occur on the image carrier and the transfer roller due to frictional heat due to the speed difference with the carrier.

Further, according to the configuration of the prior art 3, since the entire cleaning device for cleaning the transfer roller is moved up and down, the mechanism is complicated and the cost is increased, and the accuracy of the device becomes high when trying to cope with high speed. There was a problem that it decreased. On the other hand, a method of moving only the transfer roller is also proposed in the embodiment of the prior art 3, but at the time of high-speed copying, the rotation speed of the image carrier increases and the distance between the transfer sheets conveyed is short. Therefore, there is a problem that sufficient cleaning cannot be performed after the transfer process is completed and before the next transfer sheet is conveyed.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent toner filming on an image carrier or a transfer roller and to cope with high speed transfer processing. A transfer device capable of sufficiently cleaning the transfer roller.

[0007]

In order to achieve the above object, a transfer device according to a first aspect of the present invention is arranged so as to be movable toward and away from an image carrier, and transfers a toner image on the image carrier. A transfer device having a transfer roller of variable speed for transferring onto paper and a cleaning roller for cleaning the surface of the transfer roller, wherein the transfer roller is separated from the image carrier except at the transfer step. , Providing a moving means for bringing the cleaning roller into contact with or in the proximity of the cleaning roller,
Further, while in this state, the rotation speed of the transfer roller is set higher than the speed during the transfer process.

In particular, the transfer device of claim 2 is characterized in that, in the transfer device of claim 1, a bias having the same potential as that of the transfer roller is applied to the cleaning roller during the transfer step. is there.

In particular, the transfer device according to claim 3 is the transfer device according to claim 1, in a state of being in contact with or in proximity to the cleaning roller, or in a position of transferring the toner image on the image carrier to a transfer sheet. In the driving force transmission device for transmitting the rotational driving force from the main body of the apparatus to the transfer roller, the rotational force is transmitted or transmitted by a multi-pole magnetized rotor and the magnetic force of the rotor. Has a rotating body,
One of the two rotating bodies moves together with the transfer roller,
Further, the other is configured so as to face the rotating body on the transfer roller side that has moved so as to be in a state of being rotationally driven.

[0010]

In the transfer device according to the first aspect, the transfer roller is separated from the image carrier by the moving means and brought into contact with or in proximity to the cleaning roller except during the transfer step. The toner attached to the surface of the transfer roller is cleaned by the cleaning roller. Further, since the rotation speed of the transfer roller at this time is faster than the speed in the transfer step, even if the time between the end of the transfer step and the start of the next transfer step is short, the transfer The toner adhering to the roller is sufficiently cleaned as compared with the conventional device.

According to another aspect of the present invention, during the transfer step, a bias having the same potential as that of the transfer roller is applied to the cleaning roller to prevent leakage of charges from the transfer roller to the cleaning roller. .

According to another aspect of the transfer device of the present invention, when one of the two rotating bodies moves and faces the transfer roller, the rotating body faces the rotating body due to the magnetic force of the multi-pole magnetized rotating body. The body moves around without being affected by uneven rotation or vibration.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a transfer device of an electrophotographic copying machine (hereinafter referred to as a copying machine) which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of the transfer device according to the present embodiment. This transfer device transfers an electrostatic latent image and a photosensitive drum 1 as an image carrier having a toner image visualized by a developing device (not shown), and a toner image on the photosensitive drum 1. A transfer roller 2 for transferring to paper, a cleaning roller 3 for cleaning the toner on the transfer roller 2, and a cleaning roller 3 facing the photosensitive drum 1 across the entire width of the transfer roller 2;
The cleaning roller 3 includes a blade 4 that comes into contact with the cleaning roller 3 and scrapes off the toner transferred from the transfer roller 2 from the cleaning roller 3, and a moving unit 11 that switches the position of the transfer roller 2. Further, a registration roller 9 that conveys the toner image from the photosensitive drum 1 to the transfer sheet 8 in order to transfer the toner image to the transfer sheet 8 at a timing, and the transfer roller 8 is located downstream of the registration roller 9 and detects the transfer sheet 8. And the transfer paper detecting means 10 of FIG. A specific control example based on the detection signal of the detection means 10 will be described later. Further, while the transfer roller 2 is in the proximity of the cleaning roller 3, the rotation speed of the transfer roller 2 is driven faster than the speed during the transfer process.

The moving means 11 has an arm 5 which is swingably supported by a support shaft 12 as shown in FIG.
The transfer roller 2 is rotatably supported at one end thereof and the solenoid 6 is attached at the other end thereof, and the solenoid 6 is turned on / off by the above-mentioned signal so that the photosensitive drum 1 and the cleaning roller 3 The transfer roller position is switched between them. The moving means 11
The position of the transfer roller 2 may be switched using an eccentric cam instead of the solenoid 6.

A magnetic plate 7 for transmitting the rotational drive of the cleaning roller 3 to the transfer roller 2 is attached to both shafts of the cleaning roller 3 and the transfer roller 2 shown in FIG. 2A. , This magnetic plate 7 is shown in FIG.
As shown in (b), it is magnetized in multiple poles. By the way, in the case where the transmission of the rotational drive is performed by gear drive, when the transfer roller 2 is pressed against the rotating cleaning roller 3, vibration occurs due to rubbing of the tooth tips until the gears mesh with each other. , There is a risk of adversely affecting the charging. Therefore, in the present embodiment, the rotational drive of the cleaning roller 3 is transmitted to the drive transfer roller 2 in a non-contact state by the magnetic force of the magnetic plate 7, so that such a fear is prevented. Further, the magnetic plate 7 also has a function of managing a minute gap between the cleaning roller 3 and the transfer roller 2, and by maintaining the cleaning roller 3 and the transfer roller 2 at the minute gap, Toner filming is prevented.

Further, a flexible blade 4 for scraping the toner attached to the cleaning roller 3 into the case 16 is in contact with the cleaning roller 3. The blade 4 may be omitted when the cleaning roller 3 is disposable. In addition, the transfer roller 2
Does not have a drive source itself, and is adapted to be driven by the photoconductor drum 1 by the friction generated by pressing on the photoconductor drum 1 side. It is also possible to forcibly drive the transfer roller 2 during the transfer process by providing a magnetic material drive source on the photosensitive drum 1 side by the magnetic plate 7 provided on the transfer roller 2 side. In this case, since a minute gap can be provided between the surfaces of the photoconductor drum 1 and the transfer roller 2, there is no risk of toner filming on the surfaces of each other. It is also possible to improve the cleaning effect by providing a drive source on the transfer roller 2 itself and positively rotating the drive source.
However, if it is rotationally driven during the transfer step, transfer unevenness due to vibration during rotation may occur. Therefore, it is desirable that the rotational drive in this case be performed only during the transfer step.

Here, the cleaning roller 3 is provided with a drive gear 13 for transmitting a drive from a drive source of a main body (not shown) at one end of the shaft of the cleaning roller 3, and during the rotation of the photosensitive drum 1. , Always spinning. Also, when the solenoid 6 is turned on, the transfer roller 2
An application electrode 15 for applying a bias voltage to the transfer roller 2 is provided on the main body side plate 14, and during the transfer process,
The transfer roller 2 transfers the toner image formed on the photosensitive drum 1.
The transfer electric field for transferring to the side is formed. Further, a cleaning bias for moving the toner adhering to the transfer roller 2 to the cleaning roller 3 is applied between the transfer roller 2 and the cleaning roller 3 except in the transfer step. When the cleaning roller 3 is made of a conductive material, a bias having the same potential as that of the transfer roller 2 is applied to the cleaning roller 3 during the transfer process so that the transfer roller 2 moves toward the cleaning roller 3 side. It is also possible to prevent leakage of charges. As a result, it is possible to prevent the occurrence of an abnormal image caused by a defective proper charge.

In the above arrangement, the registration roller 9
The transfer paper 8 by the transfer paper detecting means 10 provided on the downstream side of
When a signal that the vehicle has entered is detected, the solenoid 6 of the moving means 11 is turned on based on this detection signal. Then, the transfer roller 2 is pressed toward the photoconductor drum 1 and brought into a state in which the transfer roller 2 and the cleaning roller 3 are close to each other with a minute gap. Due to this pressing, the transfer roller 2 is frictionally driven with the rotation of the photoconductor drum 1 and is driven to rotate at substantially the same peripheral speed as the photoconductor drum 1. And
After a lapse of a predetermined time after the trailing edge of the transfer sheet 8 conveyed by the registration rollers 9 passes through the detection means 10, that is, when the time until the trailing edge of the transfer sheet 8 passes through the transfer position A, Since the detection signal is lost, the moving means 11
The solenoid 6 is turned off. Therefore, the transfer means 2 is switched by the moving means 11 so as to separate the transfer roller 2 from the photosensitive drum 1 and press the transfer roller 2 toward the cleaning roller 3 side. It is necessary to set the above-described predetermined time for each transfer paper size in advance. The transfer roller 2 pressed against the cleaning roller 3 side is driven by the magnetic force of the magnetic plate 7 as the cleaning roller 3 rotates. At this time, the cleaning roller 3 is rotationally driven so that the transfer roller 2 is rotated at a speed higher than the rotation speed in the transfer step. Further, between the transfer roller 2 and the cleaning roller 3, a transfer step is performed. Since the electric field due to the cleaning bias is formed at times other than the time, the toner adhered to the surface of the transfer roller 2 in the transfer step is removed by the cleaning roller 3
It is quickly attracted to the side and removed before the next transfer process. Then, the toner attracted onto the cleaning roller 3 is further scraped into the case 16 by the blade 4 which is brought into contact with the cleaning roller 3.

FIG. 3 is a flowchart showing an example of control of the moving means 11 in the series of transfer steps. The flowchart will be described below. First, in step S1, the solenoid 6 is turned off, the photosensitive drum 1 and the transfer roller 2 are separated from each other, and the transfer roller 2 is pressed against the cleaning roller 3 side. Next, in step S2, the transfer paper 8 is transferred paper detection means 1
The presence or absence of a signal that has entered the detection unit of 0 is determined, and when the result is Yes, that is, when there is a signal that the transfer sheet 8 has entered the detection unit, the process proceeds to step S3, and when No, the process returns to step S1. . In step S3, the solenoid 6 is turned on and the transfer roller 2 is pressed against the photosensitive drum 1 side. In step S4, the same judgment as in step S2 is made,
If Yes, the process returns to step S3, and if No, the process proceeds to step S5. In step S5, it is determined whether or not a predetermined time has elapsed after the detection means 10 detects that the transfer paper 8 has passed through the detection portion. If Yes, that is, if the predetermined time has elapsed, step S1 If No, the process returns to step S3 to keep the transfer roller 2 pressed against the photosensitive drum 1 side.

In this embodiment, the detection means 10 detects whether or not the transfer paper 8 is present at the transfer position A. However, the transfer of the toner image onto the transfer paper 8 is normally performed by the resist. Since the transfer paper 8 is conveyed to the transfer position A by the timing control of the roller 9, if the timing control signal and the transfer paper size signal are used instead of using the detection means 10, the transfer position is improved. Since the presence or absence of the transfer paper 8 at the transfer position A can be determined by previously obtaining the passage time of the transfer paper 8 at A, the photosensitive drum 1 and the transfer roller 2 can be moved toward and away from each other. Is also good.

According to the above-described embodiment, since the blade 4 is not in direct contact with the transfer roller 2, toner filming due to frictional heat on the blade 4 and the transfer roller 2 can be prevented. Further, the transfer roller 2 is cleaned after each transfer step, and the rotation speed of the transfer roller 2 at the time other than the transfer step is faster than the rotation speed at the transfer step. Since excellent cleaning performance can be obtained even when the transfer interval of the transfer paper 8 is shortened,
It is possible to prevent the back surface of the transfer paper from being soiled. Further, since the magnetic plate 7 transmits the rotational drive of the cleaning roller 3 to the transfer roller 2 side while maintaining the transfer roller 2 and the cleaning roller 3 at a small distance, even if the cleaning roller 3 is in a rotating state, Transfer roller 2
Can be easily driven without applying vibration to the transfer roller 2 side as compared with the case where the cleaning roller 3 is driven by using a gear or when both are rotated by contacting each other. Therefore, it is possible to prevent uneven rotation during image formation.

In the above embodiment, the present invention is applied to the transfer device for directly transferring the toner image formed on the photosensitive drum 1 to the transfer paper 8. However, the present invention is not limited to this, and the photosensitive drum 1 is not limited to this. In a transfer device in which the above toner image is once transferred to an intermediate transfer body such as an intermediate transfer belt as an image carrier and then transferred to a transfer paper 8, the transfer paper is transferred from the intermediate transfer body to the transfer paper 8.
It can also be applied to the cleaning of the transfer roller 2 used for transfer to a sheet.

[0023]

According to the transfer device of the present invention, since the rotation speed of the transfer roller at the time other than the transfer step is higher than the rotation speed at the transfer step, one transfer step by the cleaning roller is performed. Each can exert sufficient cleaning performance. Further, due to continuous transfer or high-speed transfer, excellent cleaning performance can be obtained even when the transfer sheet conveyance interval is shortened, so that the back surface of the transfer sheet can be prevented from being soiled. Further, since the cleaning roller for the transfer roller is a rotating roller, unlike the case where a blade that is fixedly provided and strongly rubs the surface of the transfer roller is used, heat is not generated by friction, and the blade and the transfer roller are not generated. It is possible to prevent the toner filming to the toner and to supply a highly reliable transfer device that does not generate an abnormal image.

According to the transfer device of the second aspect, since the bias of the same potential as that of the transfer roller is applied to the cleaning roller during the transfer step, the leakage of electric charge from the transfer roller to the cleaning roller is caused. Can be prevented. Therefore, it is possible to prevent the occurrence of an abnormal image due to a defective proper charge.

According to the transfer device of the third aspect, one of the two rotating bodies moves together with the transfer roller, and the other rotates on the side of the transfer roller which is in a state of being rotationally driven. When facing the body, the other rotating body rotates together due to the magnetic force of the rotating body that is magnetized in multiple poles. Therefore, as compared with the case where gear drive is used to transmit the rotational drive, the transfer roller contacts the cleaning roller or When they are brought close to each other, a driving force can be applied to the transfer roller without affecting the transfer roller due to uneven rotation or vibration.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a transfer device according to an embodiment.

FIG. 2A is a side sectional view of the transfer device in FIG.
(B) is a multi-polar magnetized magnetic plate AA in FIG.
End view.

FIG. 3 is a flowchart showing an example of control of moving means.

[Explanation of symbols]

 1 Photosensitive Drum 2 Transfer Roller 3 Cleaning Roller 4 Blade 5 Arm 6 Solenoid 7 Magnetic Plate 8 Transfer Paper 9 Registration Roller 10 Transfer Paper Detecting Means 11 Moving Means 12 Arm Spindle 13 Drive Gear 14 Body Side Plate 15 Bias Applying Electrode 16 Case A Transfer position

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 21/10 21/14

Claims (3)

[Claims] 1. An image bearing member is disposed so as to be movable toward and away from the image bearing member,
A transfer device having a transfer roller of variable speed for transferring a toner image on the image carrier onto a transfer sheet, and a cleaning roller for cleaning the surface of the transfer roller, the transfer device except for the transfer step. A moving means is provided for separating the roller from the image carrier to bring it into contact with or in the vicinity of the cleaning roller. Further, while in this state, the rotation speed of the transfer roller is set to be higher than the speed during the transfer step. The transfer device is also characterized by being faster. 2. The transfer device according to claim 1, wherein a bias having the same potential as that of the transfer roller is applied to the cleaning roller during the transfer step. 3. The rotational driving force from the apparatus main body is transmitted to the transfer roller in a state of being in contact with or in the vicinity of the cleaning roller, or in a state of taking a position to transfer a toner image on an image carrier to a transfer sheet. A driving force transmission device for a multi-pole magnetized rotating body, and a rotating body that transmits or transmits a rotating force by the magnetic force of the rotating body, one of the rotating bodies 2. The transfer device according to claim 1, wherein the transfer device is configured so as to face the rotating body on the transfer roller side, which is moved together with the transfer roller, and the other is moved so as to be rotationally driven.