JPH0117582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method of separating a transfer paper from a photoreceptor by bringing the transfer paper close to or in contact with a conductor after transfer in an electrophotographic copying machine. The purpose is to reliably prevent the image transferred to the transfer paper from being reversely transferred to the photoreceptor after separation of the transfer paper, depending on the type and size of the paper, and the occurrence of transfer omissions.

Conventionally, when the transfer paper of an electrophotographic copying machine approaches or contacts a conductor to separate the transfer paper from the photoreceptor after transfer, a voltage with the same polarity as the transfer charge polarity is applied to the conductor. The toner transferred from the body to the transfer paper is no longer reversely transferred to the photoreceptor when separated, and transfer omission can be prevented, but there is a drawback that the separation performance becomes unstable. Therefore, in order to satisfy both of these contradictory performances, the conductor should be replaced with a resistor,
The transfer paper is grounded through a constant voltage element, or by connecting a resistor and a constant voltage element in parallel, so that the charge applied to the transfer paper from the transfer charge generates a voltage between the conductor and the ground. Even if transfer failure occurs only at the initial stage when the tip approaches or contacts the conductor, separation is ensured, and then after separation, transfer is ensured by the voltage described above, but transfer paper is used as a voltage generating means. Since the internal charge is used, the potential rise time varies greatly depending on the type and size of the transfer paper, which has the disadvantage of causing problems in both separation and transfer performance.

The present invention detects the moment when the transfer paper reaches the separation position by an appropriate means, adjusts the timing using a separately provided power supply based on this detection time, and applies a power supply voltage to the conductor, thereby eliminating the drawbacks of the conventional method. This is what I tried to remove.

Next, one embodiment shown in the accompanying drawings will be described in detail. Reference numeral 1 denotes a photoreceptor drum, on the surface of which a charged electrostatic latent image 2 is formed, and charged toner 3 is adhered thereto. A transfer paper 4 is fed by a pair of registration rollers 5 and 6, and a transfer charger 7 applies a transfer electric field to the poles.
Reference numeral 8 denotes a pulley 8 which is stretched between a first pulley 10 disposed close to the photoconductor 1 on the exit side of the transfer section and a second pulley 11 disposed at a position away from the photoconductor 1. The part facing the photoconductor 1 is a conductive belt that runs in the same direction as the photoconductor 1, and is made of a sheet of nickel with a thickness of 40 μm. It's getting old.

Next, the method of the present invention will be explained. When a polar transfer electric field is applied to the transfer paper 4 by the transfer charger 7, the polar toner on the photosensitive drum 1 is transferred to the transfer paper 4. When the leading edge of the transfer paper 4 approaches or contacts the conductive belt 8, the leading edge of the transfer paper 4 is attracted and separated by the conductive belt 8 due to dielectric action. At the same time, the moment when the transfer paper 4 reaches the separation position is detected by a paper feed registration signal, an optical system signal, and a paper edge detection sensor installed in the paper feed path, and a voltage application circuit is activated at a predetermined timing from the start of separation. 9 to apply a predetermined polar voltage to the transfer paper 4.

At the time of separation, the potential of the conductive belt 8 is zero or close to zero, so that the dielectric effect ensures the separation. However, during this separation, the toner on the transfer paper 4 is attracted to the photoconductor 1 and reversely transferred, resulting in transfer omission, but this only occurs in a very narrow part at the leading edge of the transfer paper, and once separation is performed, Since a polar voltage is applied to the transfer paper 4 at a predetermined timing, no transfer omission occurs.

According to the present invention, toner is attracted to an electrostatic latent image formed on a photoreceptor, and the resulting toner image is transferred to copy paper in a transfer section under the application of a transfer electric field, and then the copy paper In a transfer/separation device of an electrophotographic copying machine that separates the copy paper from the photoreceptor by applying an electrostatic attraction force between the conductive conveyance member and the conductive conveying member, a The first pulley is placed close to the photoconductor, and the second pulley is placed away from the photoconductor, with the part facing the photoconductor facing the same direction as the photoconductor. After the leading edge of the transfer paper is attracted and separated by an endless conductive belt that runs on the
Since a voltage of the same polarity as the charge caused by the transfer electric field of the transfer paper is applied to the conductive belt, both separation and transfer performance can be performed properly regardless of the type and size of the transfer paper. , it is possible to reliably prevent transfer failure after separation.

[Brief explanation of drawings]

The figure is a front view of an embodiment of an apparatus for carrying out the method of the present invention. 1... Photosensitive drum, 2... Electrostatic latent image, 3...
Toner, 7... Transfer charger, 8... Conductive belt, 9... Voltage application circuit.

Claims (1)

[Claims] 1. Toner is attracted to the electrostatic latent image formed on the photoconductor, and the resulting toner image is transferred to copy paper in a transfer section under the application of a transfer electric field, and then the copy paper and conductive In a transfer/separation device of an electrophotographic copying machine that separates the copy paper from the photoreceptor by applying an electrostatic attraction force between the conveying members, the copy paper is separated from the photoreceptor at the exit side of the transfer section. An endless device that is spanned between a first pulley placed close to the photoreceptor and a second pulley placed farther away from the photoreceptor, with the part facing the photoreceptor running in the same direction as the photoreceptor. Transfer/separation of an electrophotographic copying machine characterized in that after a leading edge of a transfer paper is adsorbed and separated by a conductive belt, a voltage of the same polarity as the charge of the transfer paper due to a transfer electric field is applied to the conductive belt. Device.