JPS61159678A - Transfer and separation device for electrophotographic device - Google Patents

Abstract

PURPOSE:To perform invariably stable transfer and separation by setting discharging current values and AC component frequencies of electrostatic charging before transfer, transfer charging, and separation charging to optimum values according to the kind of toner used for development. CONSTITUTION:The 1st developing device 13 and the 2nd developing device 14 contain different kind of toner. A high voltage controller 30 is provided to select current values of electrostatic charging, transfer charging, and separation charging which are optimum for various characteristics of toner in use. A before-transfer electrostatic charger 15, transfer charger 18, and separation charger 19 are put in discharging operation with the selected values.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic device such as a color electrophotographic copying device, a color recording device for a computer output section, etc., and particularly to an electrophotographic device capable of using two or more types of toner. This invention relates to a transfer and separation device.

E Liao J and 11 A conventional transfer and separation device for an electrophotographic device first transfers a latent image carrier 1, which is developed by a developing device to the photosensitive surface of a photosensitive drum, on which a visible powder image of toner is formed, before transfer. After exposure and pre-transfer charging by adding DC discharge with the same polarity as the toner polarity or AC discharge to strengthen the charge amount of the toner and eliminate the charge on the photosensitive surface to which toner is not attached, A transfer paper is brought into close contact with the photosensitive surface, the polarity of the toner is reversed on the back side of the transfer paper, and the toner on the photosensitive surface is transferred to the transfer paper using electrostatic force.

Next, the back side of the transfer paper after the transfer is charged with AC discharge or DC discharge with the same polarity as the toner.
The structure is such that the transfer paper is neutralized, the electrostatic adhesion between the transfer paper and the latent image carrier is removed, and the transfer paper is separated from the photosensitive surface using the elastic force of the transfer paper.

However, when an electrophotographic apparatus uses, for example, a multicolor developing device, two or more types of toner are used. In this case, since the electrical characteristics, particle shape, size, and other characteristics of different types of toner are not the same, the adhesion between the transfer paper and the latent image carrier after transfer is greatly different. Separability also differs greatly. Therefore, if the transfer and separation conditions are set to be the same for all toners as in the conventional configuration described above, transfer and separation can be performed for a certain toner, but other toners can also be transferred and separated. There is a drawback that stable transfer and separation cannot be performed, and re-transfer 1 separation failures occur frequently, resulting in significant deterioration and trouble in image quality and paper feeding.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a transfer and separation device for an electrophotographic device that can always perform stable transfer and separation regardless of the type of toner used.

To summarize the present invention, the following objects are completely achieved by the transfer and separation device for an electrophotographic device according to the present invention:
The present invention provides an electrophotographic apparatus that can selectively use two or more types of toner to develop an electrostatic latent image formed on the surface of a latent image carrier. By changing the current for charging, transfer charging, and separation charging,
This is a transfer and separation device for an electrophotographic device, which is characterized in that it transfers a developed visible powder image to a transfer material and separates it from a latent image carrier.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The attached drawing is a schematic configuration diagram showing an example of an electrophotographic apparatus embodying the present invention, and includes a latent image carrier 10 in the form of two cylindrical drums.
rotates in the direction of the arrow shown in the figure, and first, the Wft carrier (in the non-embodiment example), the photosensitive surface of the photosensitive drum 10 is uniformly charged by the primary charger it, and then an image corresponding to the original is exposed in the exposure section 12. , an electrostatic latent image is formed. This electrostatic latent image on the photosensitive surface is selectively developed by the next first developing device 13 or second developing device 14, and a visible powder image of the toner image is formed.

Next, a pre-transfer exposure device 16 and a pre-transfer charger 1 which performs a DC discharge of the same polarity as the toner of the visible powder image or a discharge obtained by adding AC discharge to the photosensitive surface on which the visible powder image is formed are applied.
5 is used to expose and charge the toner, strengthen the charge on the toner, and remove the charge from the areas on the photosensitive surface to which no toner is attached.Visible powder is applied to the transfer paper 20 that is brought into close contact with the photosensitive surface through the transfer guide 17. Transfer the image. This transfer is achieved by charging the back side of the transfer paper 20 with a polarity opposite to that of the toner using the transfer charger 18, and using electrostatic force to transfer the visible powder image on the photosensitive surface to the transfer paper 20. .

After that, the back side of the transfer paper 20 is charged with an AC discharge or a DC discharge of the same polarity as the toner using a separation charger 19, and the charge is removed from the transfer paper 20, thereby causing electrostatic adsorption between the transfer paper 20 and the photosensitive surface. The force is removed and the elastic force of the transfer paper 20 is used to separate the transfer paper 20 from the latent image carrier 10. Toner remaining on the photosensitive surface is removed by a cleaning device 21, and the photosensitive surface is cleaned and prepared for the next cycle.

In the electrophotographic apparatus having the above configuration, the first developing device 13
The second developing device 14 contains different types of toner. Therefore, since the characteristics of the two toners are different from each other, if pre-transfer charging, transfer charging, and separation charging are performed under the same conditions, stable transfer and separation can be performed for one toner, but for the other toner, Stable transfer and separation cannot be performed. Therefore, in the present invention, a high voltage control device 30 is provided, and current values for pre-transfer charging, transfer charging, and separation charging that are optimal for the characteristics of the toner used are selected by this control device 30, and the current values for the pre-transfer charging, transfer charging, and separation charging are selected. The pre-transfer charger 15, the transfer charger 18, and the separation charger 19 are configured to perform a discharging operation at the current value.

For example, when an l-component magnetic toner is used in the fjSl developing device 13 and a two-component non-magnetic toner is used in the second developing device 14, the amount of charge of the toner on the photosensitive surface is the latter. is larger, and the adhesion between the transfer paper 20 and the photosensitive surface of the latent image carrier 10 is better in the latter due to the difference in the type of external additive in the toner. Retransfer and separation defects are more likely to occur when the image is developed using the developing device 14.

However, in the present invention, when developing with the second developing device 14, the high voltage control device 30 lowers the pre-transfer charging D compared to when developing with the first developing device 13.
The discharge current of the C component is selected to a small value to prevent the amount of charge on the toner from becoming excessive, the transfer current is also selected to a small value to prevent toner scattering, etc., and the separation charging is performed using the current of the AC component. is selected to a large value or the frequency is set high to strengthen the static elimination effect on the transfer paper 20.

Therefore, even when developing with the second developing device 14, stable transfer and separation can be performed without causing re-transfer or separation failure as in the conventional case.

The following table shows an example of transfer and separation conditions when carrying out the present invention.

When pre-transfer, transfer, and separation discharges were performed under the conditions specified in the table above, it was found that the first
Even in the case of development by the second developing device 13 using two-component non-magnetic toner, stable transfer and separation can be performed, and re-transfer and separation failures will not occur. There were none.

In this way, in the present invention, the discharge current value and A of pre-transfer charging, transfer charging, and separation charging are adjusted according to the type of developed toner.
Since the C component frequency is selected at an optimum value, there is no occurrence of toner scattering, retransfer, poor separation, etc. during transfer, and there is an excellent advantage that stable transfer and separation can be performed at all times. Furthermore, since the high voltage control device 30 simply selects the discharge current value and frequency that match the type of toner used, the configuration is simple and there are no problems in terms of manufacturing or cost.

In the above embodiment, two developing devices are used,
Although two types of toner are used, it goes without saying that the present invention can also be applied to an electrophotographic device that selectively performs development using three or more types of toner. , transfer charging, and separation charging may be controlled differently from the above-mentioned values depending on the characteristics of the toner or the discharge distribution of various chargers for greater effect. It should be noted that.

Furthermore, it is possible to separate the pre-transfer exposure depending on the type of toner.

[Brief explanation of the drawing]

The accompanying drawings are schematic configuration diagrams showing an example of an electrophotographic apparatus embodying the present invention. lO: latent image carrier 11; primary charger 12, g tip 13, first developing device 14: second developing device 15: pre-transfer charger 16: pre-transfer exposure device 18: transfer charger 19: Separation charger 20: Transfer paper 30: High voltage control device

Claims (1)

[Claims] 1) In an electrophotographic device that can selectively use two or more types of toner to develop an electrostatic latent image formed on the surface of a latent image carrier, pre-transfer charging, A transfer and separation device for an electrophotographic apparatus, characterized in that the currents for transfer charging and separation charging are changed to transfer a developed visible powder image to a transfer material and separate it from a latent image carrier.