JPH0296787A - Transfer material separating device - Google Patents

Abstract

PURPOSE:To prevent the soil of a separating claw by providing a means electrifying the inbetween of toner images on an image carrier to polarity opposite to the toner at the position in front of the separating claw. CONSTITUTION:A main eraser lamp 2, an electrification charger 3, an inter- image eraser 4 made of an LED array, an image exposing part 5 where an optical system exposes, a developing device 6, a transfer charger 7, a separation charger 8, the separating claw 9, a cleaner 10, etc., are disposed in that order on the outer periphery of a photosensitive drum 1 in the rotating direction. Moreover, the means is provided to electrify the inbetween of toner images on the image carrier 1 to polarity opposite to the toner at the position in front of the separating claw 9. Consequently, the toner attaching to the separating claw 9 can be bonded on the side of the image carrier 1 to prevent the soil of the separating claw 9. In addition, the toner never drops to transfer material or the device, nor soils the parts.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a transfer material separation device for separating a transfer material from an image carrier after transferring a toner image in an image forming apparatus such as a copying machine or a laser printer. It is.

(Prior Art) Conventionally, in image forming devices such as electrophotographic copying machines and laser printers, photoreceptor drums (image bearing members) have been used during transfer.
As a method for separating the transfer material stuck to the photoreceptor drum l from the photoreceptor drum, a method is widely practiced in which the transfer material is peeled off using a separating claw that is brought into pressure contact with the photoreceptor drum.

If this separating claw is constantly pressed against the photoreceptor drum, the photosensitive drum will be more likely to be damaged. When the tip of the separation claw passes through, the separation claw is configured to separate the separation claw.

(Problem to be Solved by the Invention) However, the transfer efficiency is usually not 100% (because some toner remains on the photoreceptor drum even after the toner image is transferred from the photoreceptor drum to the transfer material, This residual toner adheres to the separation claw.When this adhered toner is sold in bulk, it will fall off the separation claw, especially if it spills onto the transfer material when the separation claw is separated from the photoreceptor drum. However, there is a problem in that the image becomes smeared and the image quality deteriorates.

Note that Japanese Patent Application Laid-Open No. 61-277985 discloses a device in which the surface of the separating claw is made conductive in order to prevent dirt on the separating claw, but this method is not sufficiently effective in preventing the adhesion of residual toner. I can't. Further, Japanese Patent Application Laid-Open No. 59-193477 discloses a device that is provided with a member for cleaning the separation claw, but there is a problem in that the structure becomes complicated due to the cleaning operation of the separation claw.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, it is an object of the present invention to provide a transfer material separation device that can effectively prevent toner adhering to a separating claw from spilling out with a wheel-like configuration.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a pressure contact with the image carrier so that the transfer material can be separated from the image carrier.
The present invention is characterized in that it includes a separating pawl for causing the toner images to separate, and a means for charging the inter-image area between the toner images on the image carrier to a polarity opposite to that of the toner at a position in front of the separating pawl.

(Function) Since the present invention has the above configuration, by charging the inter-image area on the image carrier at a position in front of the separation claw to a polarity opposite to that of the toner, the toner adhering to the separation claw is attached to the image carrier side. This prevents the separating claw from getting dirty and prevents the toner from spilling into the transfer material or inside the machine. Note that the toner adhering to the image carrier from the separating claw is removed by a cleaner together with the remaining toner.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 4.

First, the structure of the separating claw arrangement section will be explained with reference to FIG. Reference numeral 1 denotes a photoreceptor drum 1 serving as an image carrier, and an organic photoreceptor layer is formed on the outer peripheral surface of the drum. This photosensitive drum 1 is rotatable in the direction of arrow A, and on its outer periphery, along the direction of rotation, there are a main eraser lamp 2, a charger 3, an inter-image eraser 4 consisting of an LED array, and an image exposure section using an optical system. 5, developing device 6, transfer charger 7
, a separation charger 8, a separation claw 9, a cleaner 10, etc. are arranged in this order.

Reference numeral 12 denotes a register roller that feeds a transfer material toward the transfer section 11 between the photoreceptor drum 1 and the transfer charger 7 in synchronization with the toner image on the photoreceptor drum 1, and 13 the toner image is transferred to the photoreceptor. This conveyor belt conveys the transfer material separated from the body drum l toward a fixing section (not shown).

Then, the entire surface of the photoreceptor layer of the photoreceptor drum l is neutralized by the main eraser lamp 2, charged uniformly to, for example, a negative polarity by the charger 3, and then the image area is removed by the inter-image eraser 4. After the image is exposed and development of the inter-image area is prevented, the image is exposed in the exposure section 5 and left undisturbed. ! A latent image is formed, and then developed by a developing device 6 using toner triboelectrically charged to a positive polarity. Next, in the transfer section 11, a negative charge is applied to the back surface of the transfer material by the transfer charger 7, and the toner image on the photosensitive drum 1 is transferred to the transfer material.

Thereafter, the transfer charge is removed by a separation charger 8 to which an alternating voltage is applied, and the transfer material is separated from the photoconductor drum 1 by being peeled off by a separation claw 9, and then transported to a fixing section by a conveyor belt 13. After being conveyed and having the toner image fixed thereon, it is discharged outside the machine. The residual toner on the photosensitive drum l is cleaned by a cleaner 10.

The separating claw 9 is fixed to a shaft 14 rotatably installed parallel to the axial direction of the photosensitive drum 1 at a position rearward from the transfer section 11 in the rotational direction of the photosensitive drum 1 . This shaft 14
As shown in FIG. 2, one end of a swinging lever 15 is fixed to an appropriate location of the swinging lever 15, and a spring 16 connected to the other end of the swinging lever 15 causes the separating claw 9 to constantly hold the photosensitive drum 1.
is biased in the direction away from the Further, a plunger 17a of a solenoid 17 is connected to the other end of the swing lever 15, and the swing lever 17a resists the biasing force of the spring 16.
5 to the right in the drawing, the separating claw 9 can be brought into pressure contact with the photosensitive drum 1.

The solenoid 17 is a CP that controls the entire image forming device.
The drive is controlled via the drive circuit 18 at U20. Further, the CPU 20 includes a transfer charger 7, a separation charger 8
, register roller 12, etc. are controlled based on input signals via respective drive circuits and control means.

In the above configuration, in a normal state, the separating claw 9 is held apart from the photosensitive drum 1 by the biasing force of the spring 16 in order to prevent the photosensitive drum 1 from being damaged. When the transfer material is supplied, just before the leading edge of the transfer material reaches the position of the separation claw 9, the solenoid 17 is activated and the swing lever 15 is activated.
is driven to swing, the separation claw 9 comes into pressure contact with the photoreceptor drum l via the shaft 14, and the leading edge of the transfer material stuck to the photoreceptor drum 1 is peeled off from the photoreceptor drum 1. After that, a predetermined period of time has elapsed. The operation of the rear solenoid 17 is released, and the separation claw 9
are held apart by a spring 16.

Therefore, as shown in FIG. 3, after a predetermined time T from the drive signal for the register roller 12, the solenoid I7 is activated and the separation claw 9 is pressed against the separation claw 9, and then, after an elapse of T2, the solenoid 17 is deactivated. The separation claw 9 is released from pressure. This T, 72 hours is set based on the time T0 required for the transfer material to reach the separation claw 9 from the register roller 12. Normally, the tip of the transfer material is 20m
When the transfer material reaches the front end, the pressure contact is made and the leading edge is separated from the photosensitive drum 1. After that, the leading edge of the transfer material is separated relatively easily without contacting the separating claw 9, so that the leading edge of the transfer material reaches 40 m.
T2 and Tt are set so that the pressure contact is released after 111 has gone too far.

During the above-described separation operation of the transfer material by the separating claw 9, the separating claw 9 moves approximately 40 mm from the leading edge of the image area on the photoreceptor drum 1.
It is indirect before m111. Therefore, the residual toner after transfer in this section adheres to the separation claw 9, and the separation claw 9 becomes dirty. When the adhering toner exceeds a certain amount, it falls off the separation claw 9 and adheres to the transfer material passing under the separation claw 9, which stains the image and deteriorates the image quality.

In order to prevent this, the transfer charger 7 is kept in the on state as before, while the minute charger 8 is kept in the on state in the image area to have a function of separating the transfer material, and is turned off in the inter-image area. In this way, the transfer charger 7 charges the inter-image area of the photosensitive drum 1 to a polarity opposite to that of the toner. As a result, the toner that has adhered to the separation claw 9 and is about to fall off is attracted to the photosensitive drum 1 in the inter-image area, and the separation claw 9 is cleaned.

To explain in more detail in FIG. 4, FIG. 4 shows the separation claw 9.
((a) in the same figure), the charging state of the image area and the inter-image area after inter-image erasing ((b) in the same figure), the charging state after exposure ((C) in the same figure), and the charging state of the transfer charger 7 (((C) in the same figure). The operating state ((d) in the same figure), the operating state of the separate charger 8 ((e) in the same figure)
), and the charged state after transfer and passing through the separation charger 7.8 (([)) in the same figure. As is clear from FIG. 4 ([), after passing through the transfer and separation charger 7.8,
At a position in front of the separation claw 9, the inter-image area of the photoreceptor drum 1 is charged with a polarity opposite to that of the toner. Therefore, if toner adheres to the separation claw 9, this adhered toner is attracted to the photoreceptor drum 1. It is.

Conventionally, both the transfer charger 7 and the separation charger 8 are continuously maintained in the on state, so as shown in FIG. It is not effective in adsorbing l/ner adhering to the separating claw 9.

In the above embodiment, an example was shown in which the photoreceptor drum 1 is charged to the opposite polarity to the toner at a position in front of the separation claw by controlling the operating states of the transfer charger 7 and the separation charger 8. Another charger may be provided at a position in front of the battery to charge the battery.

Further, as shown by imaginary lines in FIG. 1, means 19 for selectively applying a positive potential and a negative potential to the separating claw 9
A potential of opposite polarity to the toner is applied to the separating claw 9 to hold the attached toner during the transfer passage, that is, while the image area is passing, and when the transfer material is not passing, that is, the image area. An even greater cleaning effect can be obtained by applying a potential of the same polarity as the toner during the passage of the toner to repel the attached toner.

Note that the switching timing of the voltage applied to the separation claw 9 is based on the drive start signal of the register roller on the tip side, and should be switched with a margin of about 10 to 20 mm from the edge of the image, or synchronized with the pressure contact timing of the separation claw 9. Alternatively, on the trailing edge side, passage of the trailing edge of the transfer material may be detected by an ultrasonic sensor or the like, and switching may be performed based on the detection signal. Further, the timing of these switching is preferably controlled by the CPU 20. The potential applied to the separation claw 9 with the opposite polarity to the toner is preferably set to be lower than the surface potential of the photoreceptor drum 1 to make it difficult for residual toner to adhere to the separation claw 9. Since the image potential is usually about -600V, the potential is -300 to -300V. Approximately -400V is desirable.

(Effects of the Invention) According to the transfer material separation device of the present invention, as is clear from the above description, by charging the inter-image area on the image carrier to the opposite polarity to the toner at a position in front of the separation claw, The toner attached to the separation claw can be attached to the image carrier side.

Therefore, it is possible to prevent the separating claw from becoming dirty, and the toner is not spilled into the transfer material or the machine body, thereby preventing it from becoming dirty.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, FIG. 1 is a schematic diagram of the main parts, FIG. 2 is a block diagram of the control section, FIG. 3 is an operation timing diagram of the separation claw, and FIG. FIG. 4 is an explanatory diagram of the action.

Claims (1)

[Claims] (1) A separation claw that separates and presses against the image carrier to separate the transfer material from the image carrier, and a position in front of the separation claw that separates the image area between the toner images on the image carrier. A transfer material separation device comprising means for charging the toner to a polarity opposite to that of the toner.