JPH09269672A - Transfer carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To press a transfer charge applying means on a transfer belt or release the pressing, accompanying the start or stop of driving a transfer belt, without increasing the cost and complicating the constituting by providing a pressure generating member. SOLUTION: When the transfer belt 5 is driven in the direction of arrow (b) by a driving roller 19, in the contact part of a plate-like urethane rubber 28 with the belt 5, frictional force in the direction of arrow (c) is exerted on the urethane rubber 28, in accordance with the driving of the belt 5. The force is transmitted to a support 17a and a transfer brush support 17 in order, as the force in the direction of arrow (d) on supporting shafts 27a and 27. Consequently, the force toward a photoreceptor drum 1, on the supporting shaft 27 is exerted on a transfer brush, as energizing force in the direction of arrow (e). The transfer brush is pressed on the inside surface of the belt 5 coming into contact with the drum 1, to enable a transfer. Further, when the driving of the belt 5 is stopped, the frictional force applied to the urethane rubber 28 is eliminated so that the pressing of the transfer brush on the belt 5 can be released as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer / conveyance apparatus, and more particularly to a belt transfer-type transfer / conveyance apparatus used in an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, in order to electrostatically transfer a toner image on an image carrier formed by an electrophotographic method to a transfer material, a transfer material is carried on a belt-shaped transfer material carrying member and transferred and carried. A so-called belt transfer method has been proposed. Proposed examples include US Pat. No. 5,249,022 and JP-A-2
There is one disclosed in Japanese Patent Publication No. 170176. A transfer belt type of a monochrome type image forming apparatus, a tandem color image forming apparatus or the like has been commercialized.

As a transfer charge applying means used in this belt transfer system, there has been proposed a contact type transfer charge applying means for applying a charge for the transfer by bringing a transfer brush, a transfer roller or the like into contact with the inner surface of the belt. There is. When using these contact type transfer charge applying means, it is necessary to press the transfer charge applying means against the transfer belt. This is because the contact-type transfer charge applying unit supplies the transfer charge only to the contact region of the transfer belt, and therefore the contact region needs to be secured in order to secure a sufficient transfer region. A spring is generally used as a method of pressing the contact-type transfer charge applying unit against the transfer belt.

By the way, when the transfer belt is in a driving stop state, such as when the image forming apparatus is on standby or stopped, if the transfer charge applying means is still pressed against the transfer belt,
When the pressure of the charge applying unit acts only on a part of the transfer belt, the transfer belt at the pressed portion may be permanently deformed and the transferred image may be disturbed at that portion. Further, when there is an image carrier on the opposite side of the pressing part, the transfer belt is constantly in contact with the image carrier while the transfer belt is stopped by the pressing, and as a result, the contact part is charged with a charge. There is also a case where a so-called touch memory that remains is generated on the image bearing member and image disorder occurs.

In order to prevent these problems, conventionally, when the transfer belt is stopped, a releasing solenoid or motor is provided so as to release the contact type transfer charge applying unit from pressing the transfer belt. The control is performed in response to the stoppage to operate these to release the pressing.

[0006]

However, the above-mentioned conventional method requires a solenoid and a motor for releasing the pressing force, and means for transmitting the release driving force thereof, so that the cost is increased accordingly and the apparatus is There is a problem that the configuration becomes complicated.

An object of the present invention is to provide a transfer / transporting device capable of pressing and releasing the transfer charge applying means to the transfer belt when driving and stopping the driving of the transfer belt without increasing the cost and complicating the structure. To provide.

[0008]

According to a first aspect of the present invention, there is provided a transfer / conveying device which transfers a toner image on an image carrier to a transfer belt which is in contact with the image carrier and a transfer material which is carried and carried by the transfer belt. In order to provide the transfer charge to the transfer belt and the image carrier in the vicinity of the contact portion, the transfer charge is provided to transfer the transfer charge to the inner surface of the transfer belt. It is characterized in that a pressing force generating member for urging the applying means in the direction of the image carrier is provided.

According to this structure, a part of the pressing force generating means is in contact with the transfer belt in the vicinity of the contact portion between the transfer belt and the image carrier, so that the transfer belt is driven. Receives a frictional force between the transfer belt and the transfer belt, and this frictional force is transmitted to the transfer charge imparting means so as to bias the transfer charge imparting means in the direction of the image carrier, thereby transferring the transfer charge imparting means to the image carrier. When the transfer belt is in contact with the transfer belt, and when the transfer belt is stopped, the frictional force is not generated, so that the pressing force for urging and pressing the transfer charge applying unit toward the image carrier is released. The transfer charge applying means is automatically pressed against the transfer belt at the same time as the transfer belt is driven without requiring a solenoid, a motor, or a motion transmitting mechanism between these and the transfer charge applying means. Transfer charge at the same time It is possible to release the pressure on the transfer belt given unit automatically, the cost is reduced, the structure of the apparatus is simplified.

According to a second aspect of the present invention, in addition to the first aspect of the present invention, the support of the transfer charge applying means further has a fulcrum shaft for pressing the transfer charge applying means against the transfer belt, and the pressing force generating member is provided. It is provided on the opposite side of the fulcrum shaft from the transfer charge applying means.

In such a structure, the support itself of the transfer charge applying means is rotated about the fulcrum axis between the transfer charge applying means and the pressing force generating member, whereby the pressing force generating member and the transfer belt are moved. A lever member that switches the frictional force between the transfer charge applying means and the pressing force of the transfer charge applying means to the transfer belt is formed, and the transfer charge applying means presses and presses the transfer belt when the transfer belt is driven and stopped with a simple structure. Release can be achieved with high responsiveness. Also, depending on the setting of the lever ratio, there is an advantage that a large pressing force can be obtained even with a small frictional force.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described in detail below with reference to the drawings.

(First Embodiment) The first embodiment is shown in FIG.
The present invention is applied to an electrophotographic image forming apparatus whose schematic configuration is shown in FIG. A photosensitive drum 1 which is an image bearing member of this image forming apparatus is rotationally driven in a direction of an arrow a shown in the drawing, and around the periphery thereof, a charging charger 2, a print head 3, a developing device 4, a transfer belt 5, a cleaner 6, Eraser 7 etc. are arranged.

The transfer belt 5 is formed of a film belt made of PVDF (polyvinylidene fluoride), PC (polycarbonate), or the like, or a rubber belt made of CR rubber, urethane rubber, or the like. Further, it is stretched by a driven roller 20, and is driven in the direction of arrow b in synchronization with the photosensitive drum 1.

Around the transfer belt 5, the photosensitive drum 1 is provided.
In order to transfer the toner image on the sheet P which is the transfer material on the transfer belt 5, the transfer brush 1 which is a conductive brush as a transfer charge applying unit that contacts the inner surface of the transfer belt 5
6, a conductive transfer brush support 17 that supports the transfer brush 16, a DC power source 18 connected to the transfer brush support 17, and a separation claw 1 that separates the paper P from the transfer belt 5.
4, belt cleaner 2 that cleans the outer surface of the transfer belt 5
1. A static elimination brush 22 for eliminating static electricity on the inner surface of the transfer belt 5, a static elimination brush 23 for eliminating static electricity on the outer surface of the transfer belt 5, an AC power source 24 for static elimination connected to the static elimination brushes 22, 23, and a transfer belt 5 of the driven roller 20 section. A direct current power supply 26 and the like connected to the grounded conductive counter roller 25 and the driven roller 20 which are in contact with the outside are provided.

The paper P sent out from the paper tray 10 by the paper feed roller 11 is guided to the timing roller 9 by the guide 12, synchronized with the photosensitive drum 1 by the timing roller 9, and then the DC power source 26 as described above. It is sent between the driven roller 20 connected to and the counter roller 25 which is grounded, and electrostatically attracted to the transfer belt 5.

The sheet P carried on the transfer belt 5 in this manner is conveyed in the direction of arrow b as the transfer belt 5 is driven by the drive roller 19. When the paper P reaches the transfer position between the photoconductor drum 1 and the transfer belt 5, the transfer brush 16 inside the transfer belt 5 supplies the transfer charge to the transfer belt 5 to form a toner image on the photoconductor drum 1. It is electrostatically transferred onto the paper P.

The toner used in the image forming apparatus shown in FIG. 1 has a triboelectrification polarity of (-) polarity, and a transfer brush 16 is applied with a voltage of 2 KV of (+) polarity from a DC power source 18 to transfer the toner. It is carried out.

The sheet P on which the toner image is transferred is conveyed while being attracted to the transfer belt 5, and is separated from the transfer belt 5 by the separation claw 14. Then, the sheet is guided to the fixing portion by the guide 15, fixed by the fixing roller 8, and discharged to the paper discharge tray 13.
Discharged to the top.

The transfer belt 5 from which the paper P has been peeled off is first cleaned on the outer surface by the belt cleaner 21, and then on the inner and outer surfaces of the transfer belt 5 by the charge removal brushes 22 and 23. In the first embodiment, the static elimination brush 22,
The charge removal of the transfer belt 5 is performed by 23, but other charge removing means such as a corona charger may be used. Further, although the AC power supply 24 is connected, it may be an AC power supply on which DC is superimposed or a DC power supply.

The main part of the first embodiment will be described in detail below. As the transfer belt 5, PVDF (polyvinylidene fluoride) having a surface and volume resistance of 10 ¹⁴ Ω · cm and a thickness of 150 μm is used. In addition, the transfer brush 16 is obtained by weaving conductive brush thread on a conductive cloth and then cutting the conductive brush thread, and the conductive brush thread is bonded to an aluminum transfer brush support 17 as shown in FIG. 3 by a conductive adhesive. Normally, it is provided so as to weakly contact the inner surface of the transfer belt 5 directly below the photosensitive drum 1. The transfer brush 16 has a density of 50,000 F (filler) / inch ² and is made of a material in which conductive carbon is mixed with rayon resin so that the electric resistance is 10 ⁴ Ω · cm.

The static elimination brushes 22 and 23 are also made of the same material and have the same manufacturing method, and the description thereof will be omitted. 2 and 3, fulcrum shafts 27 are provided at both ends of the base portion of the transfer brush support 17 that supports the transfer brush 16 upward, and the support brushes 17 and the transfer brush 16 are provided at both ends. The fulcrum shaft 27 is in a rotatable state. In addition, a plate-shaped insulating urethane rubber 28 as a pressing force generating member is attached downward to the other support 17a, and one end of the plate-shaped urethane rubber 28 has a transfer brush on the inner surface of the transfer belt 5. The fulcrum shafts 27a are provided at both ends of the base portion which is in contact with the portion on the opposite side opposite to the portion with which the 16 contacts.

With this structure, when the transfer belt 5 is driven in the direction of the arrow b by the drive roller 19, the contact portion of the plate-shaped urethane rubber 28 with the transfer belt 5 is accompanied by the drive of the transfer belt 5. The frictional force in the direction of arrow c is applied to the plate-shaped urethane rubber 28. This force is sequentially transmitted to the support 17a and the transfer brush support 17 as a force in the direction of the arrow d with the fulcrum shafts 27a, 27 as the fulcrum. As a result, a force is applied to the transfer brush 16 in the direction of the photoconductor drum 1 about the fulcrum shaft 27, that is, an urging force in the direction of arrow e, and the transfer brush 16 is in contact with the photoconductor drum 1. The belt 5 is pressed against the inner surface of the belt 5 and is ready for transfer.

When the driving of the transfer belt 5 is stopped,
Since the frictional force applied to the plate-shaped urethane rubber 28 disappears, the pressing of the transfer brush 16 on the transfer belt 5 is released, and the original weak contact state is established.

The plate-shaped urethane rubber 28 is not limited to this, and may be another rubber material or mylar as long as it produces a frictional force at the contact point with the transfer belt 5. Further, in the first embodiment, the transfer brush support 17 and the support 17a are used together, and the frictional force in the direction of arrow c between the transfer belt 5 acting on the plate-shaped urethane rubber 28 and the transfer belt 5 is transferred. Is converted into a force in the direction of arrow e that is pressed by the transfer belt 5, and the movement direction is changed. However, basically, the fulcrum shafts 27 and 27
a and the support members 17 and 17a are the same as each other in the biasing operation.
The support 17a and the support 17a may be integrated, and the fulcrum shaft 27 or 27a may be provided at one place between the transfer brush 16 and the plate-shaped urethane rubber 28. However, in this case, the transfer brush 16 needs to contact the inner surface of the transfer belt 5 from the opposite direction to the state shown in FIG.

In summary, in the first embodiment, the transfer charge is transferred at the same time when the transfer belt 5 is driven, without the need for the solenoid and the motor required conventionally and the drive transmission mechanism between these and the transfer charge applying means. It is possible to automatically press the transfer brush 16 which is the applying means against the transfer belt 5 and automatically release the pressing of the transfer brush 16 onto the transfer belt 5 at the same time when the transfer belt 5 is stopped, which reduces the cost. The device configuration is simplified.

Further, the transfer brush 16 and the supports 17 and 17a of the plate-shaped urethane rubber 28 themselves are the transfer brush 1.
The fulcrum shafts 27, 2 are provided between the 6 and the plate-shaped urethane rubber 28.
By the rotation around 7a, the plate-shaped urethane rubber 2
And a lever member for switching the frictional force between the transfer belt 5 and the transfer belt 5 to the pressing force of the transfer brush 16 to the transfer belt 5,
With a simple structure, the transfer belt 5 can be driven and stopped, and the transfer brush 16 can be pressed and released on the transfer belt 5 with good responsiveness. Also, depending on the setting of the lever ratio, there is an advantage that a large pressing force can be obtained even with a small frictional force.

(Embodiment 2) In Embodiment 2, as shown in FIG. 4, a transfer roller 29 as a transfer charge applying means.
A specific example of the case where one transfer roller support 30 having a fulcrum shaft 31 is used to support the plate-shaped urethane rubber 28 serving as a pressing force generating member, and the configuration is more than that of the first embodiment. It will be simpler and cheaper.

The same members as those in the first embodiment are designated by the same reference numerals, and only different points from the first embodiment will be described.

The transfer roller 29 has an electric resistance of 10 ⁶
A urethane roller having an Ω and a diameter of 18 mm is used, and the transfer belt 5 is driven by the transfer belt 5 at the same speed.

Also in the second embodiment, as in the case described with reference to FIG. 2, friction in the direction of the arrow c generated by the driving of the transfer belt 5 at the contact portion between the plate-shaped urethane rubber 28 and the transfer belt 5. The force is transmitted to the lower portion of the transfer roller support 30 as a force in the direction of the arrow d, and is present between the transfer roller 29 and the plate-shaped urethane rubber 28.
A force in the direction of the arrow e with the fulcrum shaft 31 as the fulcrum is applied to the transfer roller 29. As a result, the transfer roller 29 moves toward the arrow e.
The component force f of the force in the direction of the normal direction at the contact point between the transfer belt 5 and the transfer roller 29 is pressed against the inner surface of the transfer belt 5 so that the transfer is possible. Further, when the driving of the transfer belt 5 is stopped, the frictional force applied to the plate-shaped urethane rubber 28 disappears.
Is released.

[0032]

According to the transfer / conveying device of the first aspect of the present invention, the solenoid and the motor, and the drive transmission mechanism between these and the transfer charge applying means are not particularly required, and the transfer is performed simultaneously with the driving of the transfer belt. The charge applying unit can be automatically pressed against the transfer belt, and the transfer charge applying unit can be automatically released from the transfer belt at the same time when the transfer belt is stopped, reducing the cost and simplifying the device configuration. become.

According to a second aspect of the present invention, in addition to the first aspect of the invention, the transfer charge applying means automatically presses or releases the transfer belt with a simpler structure when the transfer belt is driven or stopped. Can be achieved more responsively.
Further, depending on the setting of the lever ratio by the support, there is an advantage that a large pressing force can be obtained even with a small frictional force.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of the first embodiment.

FIG. 3 is a perspective view showing a transfer brush used in the first embodiment and a support for the transfer brush.

FIG. 4 is a configuration diagram of a main part of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 5 Transfer belt 16, 29 Transfer charge applying means 17, 17a, 30 Support 27, 27a, 31 Support shaft 28 Pressing force generating member

Claims (2)

[Claims] 1. A transfer belt in contact with an image carrier, and a transfer material carried on the transfer belt to transfer a toner image on the image carrier to a transfer material in the vicinity of a contact portion between the transfer belt and the image carrier. In a transfer conveyance device including a transfer charge applying unit that contacts the inner surface of the belt and applies the transfer charge, a part of the transfer conveying unit contacts the inner surface of the transfer belt so that the transfer charge applying unit is attached in the direction of the image carrier. A transfer / conveyance device comprising a pressing force generating member for urging. 2. A support of the transfer charge applying means has a fulcrum shaft for pressing the transfer charge applying means against the transfer belt,
The transfer conveyance device according to claim 1, wherein the pressing force generating member is provided on the side of the fulcrum shaft opposite to the transfer charge applying unit.