JPS6392978A - Separate charger - Google Patents

Abstract

PURPOSE:To attain stable and efficient separation for a long period by arranging a separation charger formed by a destaticizing stylus and a block consisting of an insulating material supporting the stylus on the downstream side of a transfer charger and setting up to surface resistance of the block to a prescribed conditional value. CONSTITUTION:The separation charger 3 formed by the block 3b consisting of the insulating material such as synthetic resin and the destaticizing stylus 3a planted into the block 3b is unitedly and adjacently arranged with/to one side of a shield case 2a of the transfer charger 2 on the downstream side of the charger 2 in the traveling direction of a photosensitive body 1. A groove-like recessed part is formed on the block 3b in its longitudinal direction on the opposite side to the photosensitive body 1 and the point part of the stylus 3a is exposed, opposed to the photosensitive body 1 and connected to a high voltage power supply 5. At least a part of the surface of the block 3b is constituted so as to have resistance values 10<6>-10<15>OMEGAcm as shown by number 7 and the part is connected to the earthed shield case 2a.

Description

Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus that uses an electrostatic transfer process, such as an electrostatic copying machine or a printer, and particularly to a separation charger thereof. It is.

(Prior Art and Issues to be Solved) There is a problem with a well-known image forming apparatus configured to electrostatically transfer a transferable toner image on the surface of an image carrier onto a sheet-like transfer material, mainly a sheet of paper. In order to transfer the charged toner to the transfer material, a charge of opposite polarity to the toner is applied to the back surface of the transfer material at the transfer site, and the electrostatic adsorption force between this and the toner is utilized. Normally, the transfer is performed by

In such a device, the presence of electric charge applied to the transfer material during transfer tends to cause the transfer material to stick to the image carrier after transfer, so it is necessary to actively separate the two.

A number of proposals have been made for separation means for this purpose. For example, one has a structure similar to that of a transfer charger, and this applies an electric charge of opposite polarity to the transfer material to transfer it. Things that neutralize the electric charge of time are well known.

However, such a device requires a separate power source for separation, and is inevitably inconvenient not only from a cost perspective but also from a space perspective in view of the recent trend toward miniaturization of image forming apparatuses.

In order to avoid such drawbacks, a block made of an insulating material having a Kt and integrated with the transfer charger is provided with a large number of needle-like members or sawtooth-like members facing the transfer material, and the image carrier or the A type of transfer material that eliminates static electricity from the transfer material by constantly applying a voltage of opposite polarity to that during transfer, which does not start discharge between the transfer material and the transfer material, is difficult.

This type of structure has made it possible to provide a small and inexpensive separation means, but on the other hand, this type of device may have insufficient separation effect at low humidity, and also requires a large number of sheets. If images were created continuously, there was a risk that the separation function would gradually deteriorate.

This is because the surface of the insulating block that supports the static elimination needle is gradually charged up by the discharge charge of the static elimination needle, and as a result, the surface potential of the block increases, and the contrast with the static elimination needle potential becomes smaller, causing the discharge current of the static elimination needle to increase. suppressed,
This is thought to be due to the fact that the adsorption force of the transfer material cannot be sufficiently weakened, and this tendency becomes more pronounced when the humidity is low.

The present invention has been made in order to cope with such a situation, and it is an object of the present invention to provide a separation device that can always maintain a good separation function regardless of the environment or the number of images. This is the purpose.

(2) Object of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention provides a transfer charger, an insulator integrated with the charger, and an insulator equipped with a static elimination needle. In a separation device consisting of a block made of material, the surface of the insulating block is
It is characterized by surface treatment to prevent charge-up.

By configuring in this manner, it is possible to prevent the potential contrast of the static eliminating needle from decreasing as described above, and to always perform a good separation function.

(Description of an Embodiment) FIG. 1 is a side view of a main part showing an embodiment in which the present invention is applied to a copying machine equipped with a cylindrical photoreceptor that rotates once. A shield case 2 extends parallel to the photoconductor 1 in the vicinity of the photoconductor 1 traveling in the direction of the photoconductor.
A transfer charger 2 consisting of a high voltage charging wire 2b and a high voltage charging wire 2b installed in the transfer charger 2 is disposed.
It is assumed that the toner image on the surface of the photoreceptor is transferred to the transfer material supplied along the chain line P.

As is well known, around the photoreceptor 1, there are of course a negative charger, an image signal applying means, a developing device, a cleaning device, and other members necessary for image formation. Since they are not directly related to the present invention, they are all omitted.

On the downstream side of the transfer charger 2 as seen in the traveling direction of the photoreceptor 1, on one side of the shield case 2a of the charger 2, there is a block 3b made of an insulating material such as synthetic resin made of an appropriate material.
and a static elimination needle 3a disposed thereon.
are integrally arranged adjacent to each other.

As shown in the figure, the block 3b has a groove-shaped recess formed in the longitudinal direction on the side facing the photoconductor, so that the tip of the static elimination needle is exposed and is exposed to the photoconductor or the transfer material passing through. They face each other and are connected to a high voltage power source 5.

With this configuration, the charge eliminating needle 3a does not normally discharge between itself and the photoreceptor, but only when the transfer charger 2 operates, discharge occurs to perform a separation action.

As mentioned above, in such a configuration, the potential of the block 3b, especially on the surface near the static eliminating needle, gradually rises due to the discharge of the static eliminating needle, and as a result, the potential contrast of the static eliminating needle weakens, and the discharge is suppressed to prevent transfer. There is a risk that static electricity removal from the material may be insufficient, resulting in poor separation.

Therefore, in the present invention, as shown by reference numeral 7 in the figure, at least a portion of the surface of the block 3b has a resistance of 10'.
It is configured to have a value of -101sΩC1, and this part is connected to a shield case that is grounded.

In order to construct the block in this manner, the block may be formed of such a material, and an appropriate substance may be coated on the surface of the block or a t-film may be formed.

With the above configuration, the charge on the block caused by the discharge of the static eliminating needle escapes to the ground, and the block surface will not be charged up even when used for a long time in low humidity, and a stable separation function can be expected.

Experimental examples of the present invention will be explained.

-5.3KV to the charging wire of the transfer charger, +3.5 to the static elimination needle
KV(7) voltage was applied, 52g/m was horizontally oriented in the direction of travel in an environment of 15°C and 1O%RH.
A paper-threading test was conducted using A4-sized thin paper.

(If the surface of Xun Static Eliminator Pro 5 is 10"0cm,
Separation was performed normally for the 1st to 8th sheets, but on the 9th sheet, the separation was already poor and the transfer paper adhered to the photoreceptor.

At this time, the surface potential of the block was 2.9 KV.

■ The surface resistance of the static elimination needle block is 1OIs or 10G.
When it was within the range of Ωc11 and grounded by contacting the shield case of the transfer charger, stable separation was performed not only on the 10th sheet of transfer paper but also on subsequent sheets.

The surface potential of the block at this time is 2.8 to 2, OK
It was V.

(When the surface resistance of the ψ block is io'ocm, when it is grounded as shown above, a leak occurs in a part of the static elimination needle.

Based on these results, the surface resistance of the block is set to 10'-
It has been found that good results can be obtained when the resistance is 101 Ωcm.

Although the present invention has been described above with respect to a copying machine having a rotating cylindrical photoreceptor, it is noted that the present invention can be applied to copying machines having other configurations, and furthermore, to image forming apparatuses other than copying machines. This should be easy to understand.

(3) Effects of the Invention Since the present invention has the configuration described above, it is possible to stably perform good separation over a long period of time regardless of the environment or the usage condition of the image forming apparatus.

[Brief explanation of the drawing]

FIG. 1 is a side view of a main part showing an embodiment in which the present invention is applied to a copying machine, and FIG. 2 is an enlarged perspective view of a part of the same. 1-...Photoreceptor, 2...Transfer charger, 3...Separation charger,

Claims (1)

[Claims] In an image forming apparatus including a traveling image carrier and a transfer charger disposed close to the image carrier, a charge eliminating needle and a charge eliminating needle are supported downstream of the transfer charger when viewed in the running direction of the image carrier. A separation charger formed of a block made of an insulating material is arranged, and the surface resistance of the block at least on the upstream side of the static elimination needle is set to 10^6 to 10^1.
A separation charger with 5Ωcm and a part of the surface grounded.