JPS63154571A - Guide device for transfer material - Google Patents

Abstract

PURPOSE:To reduce the size of a device, to prevent turbulence of a picture due to discharge of a transfer material, and to prevent fly of a toner due to electrification of a guide member, by a method wherein a guide member, guiding transfer of a transfer material, forms double constitution of a thin insulating layer and a conductive layer, and a voltage having the same polarity as that of a transfer change is applied on the conductive layer. CONSTITUTION:When a transfer material is separated from a sensitized substance 1 after transfer, a distance therebetween is rapidly increased, and the earth capacity of the transfer material is extremely decreased. Since, although the potential of the separated transfer material is increased by a residual charge during transfer, a voltage is applied on a Conductive layer 7b of a guide member 7, an electric field being so high enough to allow generation of discharge is not generated between the guide member 7 and the transfer material. A residual charge is enoughly eliminated by means of two destaticizing needles 5 and 6, and turbulence of a picture due to discharge is prevented from occurring. In an electric field generated by friction electrification generated between the transfer material and the guide member 7, an electric field being locally high is prevented from generation since an insulating layer 7a is thin. In potential distribution produced to this extent, flying phenomenon of a toner is prevented from occurring.

Description

Detailed Description of the Invention (1) Object of the Invention (Field of Industrial Application) This invention relates to an image forming apparatus that utilizes an electrostatic transfer process, such as an electrostatic copying machine or a printer, and particularly to a transfer material guiding device thereof. It is related to.

(Prior art and issues to be solved) A process of transferring a transferable toner image formed on the surface of an image carrier by contacting it with a sheet-like transfer material such as paper, and then separating this transfer material from the image carrier. Repetitive image forming devices are well known in the art.

In this type of image forming apparatus, conventionally, after the transfer material is transferred through a transfer site equipped with a transfer charger disposed close to the image carrier, the transfer charger is placed in the vicinity of the image carrier. A configuration in which a separation charger is provided on the downstream side has been widely put into practical use.

However, in recent years, this type of image forming apparatus has become significantly smaller and lighter, and as a result, the diameter of the image carrier, which is usually formed in a rotating cylindrical shape, has become smaller, and the space required for the arrangement of various image forming members has also become smaller. Therefore, instead of using large separation means such as a separation charger, 4
A static eliminating needle made of a plate material with a serrated tip is disposed downstream of the transfer charger to eliminate static electricity from the dry photographic material. Separating means or small separating means such as separating claws are gradually coming into practical use to separate transfer materials.

Furthermore, when conveying the separated transfer material to the next fixing site, a fixed guide member is now used instead of a conveyor belt that runs to guide the transfer material.

Since such a guide member is usually made of a synthetic resin molded product, when a transfer material is passed over this surface, it is inevitable that the guide member will become charged due to the friction between the two.

In this case, the contact status between the two differs depending on the location, so
A locally strong electric field may be generated, and particularly when this electric field acts in a direction that repels the toner on the transfer material, there is a risk that the toner will be scattered and the image will be disturbed.

In order to avoid such inconveniences, for example, it is possible to form the guide member from a low-resistance material, but if this is done, the residual charge remaining on the transfer material will be discharged, resulting in image distortion. was there. In addition, it is possible to select a material for the guide member that has a low coefficient of friction with the transfer material, or a material that has a charge polarity opposite to that of the toner. Since various materials such as paper and film are used, it is practically impossible to select materials suitable for all transfer materials.

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 transfer material guiding device that can always obtain good images regardless of the type of transfer material. .

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention includes an image carrier and a transfer charger disposed close to the image carrier, In an image forming apparatus in which a static eliminating member is disposed downstream of a transfer charger when viewed in the running direction, and the separated transfer material is guided to the next process by a fixed guide material, □
This problem is characterized in that the guide member has a superimposed structure of a thin insulating layer and a conductive layer, and a voltage of the same polarity as the transferred charge cannot be applied to the conductive layer.

With this configuration, even if the potential of the separated transfer material is high, no discharge is generated between the guide member and δ, and frictional electrification is also prevented from being applied to the guide member. Since the variation range i can be maintained within a small range compared to the voltage, a strong electric field is not generated locally, and toner scattering can be prevented.

(Description of Embodiments) FIG. 1 is a side view of essential parts of an embodiment in which the present invention is applied to a copying machine equipped with a rotating cylindrical image carrier (photoreceptor). The toner image formed on the photoconductor 1 rotating in the direction of arrow A is transferred to the photoconductor 1 in synchronization with the transfer material (not shown) conveyed by the conveyance path 2.
The transfer material reaches a transfer site equipped with a transfer charger 3 and is transferred to a transfer material, and is then separated from the photoreceptor and fed to the next process through a conveyance guide 8.

Note that this copying machine will be described assuming that the toner is negatively charged.

The conveyance guide 8 is disposed on the downstream side of the transfer charger when viewed in the traveling direction of the transfer material, and when viewed from the transfer charger 3 side, the first static elimination needle 5, the insulating layer 7a on the surface, and the conductive layer on the inside. It has a guide member 7 formed from 7b and a second static elimination needle 6,
Furthermore, on the downstream side, a guide section 9 is formed to guide the transfer material to the fixing site.

It goes without saying that a negative charger, an image signal applying means, a developing device, a cleaning device, and other members necessary for forming a solid image are arranged around the photoreceptor 1, and all of these are provided in the present invention. Since they are not directly related, they are all omitted.

In such a device, a voltage of the same polarity as that of the transfer charger, in this case +2000 V, is applied to the conductive layer 7b of the guide member 7, and the shield of the transfer charger and each static elimination needle are grounded. .

The insulating layer 7a is made of a material having a resistance of 10I4ΩCf11 or more, such as polyethylene, polyester, tetrafluoroethylene, polyamide, polyimide, polyvinylidene fluoride, etc.
, iron, Sus, etc., with a thickness of 0 on the surface of the conductive layer 7b.
．． It is formed by adhesion or coating to a length of 54 mm or less.

After the transfer, when the transfer material separates from the photoreceptor, the distance between the two rapidly increases, and the ground capacity of the transfer material becomes extremely small. Residual charge remains on the transfer material during transfer, and for this reason, its potential is high, ranging from 1000 to 3000
It will be about V.

However, since the voltage of +2000V is applied to the conductive layer of the guide member 7 as described above, an electric field sufficient to cause discharge is not generated between the transfer material and the guide member.
Since a strong concentrated electric field is generated between the two charge-eliminating needles, residual charges on the transfer material are sufficiently removed by the charge-eliminating needles, and henceforth, image disturbances due to discharge during transportation will not occur.

As for the frictional electrification that occurs between the transfer material and the guide member 7, the electric field that is generated is small because the insulating layer is thin.
No locally strong electric field is generated. This means that the charge generated by frictional electrification is at most 10-'c
/m-, and the capacitance of the guide member 7 is 3.3X if the dielectric constant of this kind of insulating layer is about 2 to 5 and the thickness of the insulating layer is 0.54 mm or less. 10-
Since it is 8 F/m' or more, the potential distribution due to frictional charging is generally within 30 Ov.

Figure 2 shows the potential distribution in the longitudinal direction on the guide member, based on the voltage applied to the conductive layer, which is +2000V. It has been confirmed that toner scattering does not occur with any transfer material as long as the toner scattering phenomenon is satisfied.

Curve a in FIG. 3 represents the case where the conductive layer 7b is grounded.
This is a potential distribution generated by frictional charging with the transfer material, and although no strong local electric field is generated, since the absolute value of the potential is less than +300V, discharge from the transfer material is likely to occur, and in this case, Since the capacitance on the guide member side is large,
A considerable amount of discharge occurs before the discharge stops, resulting in image disturbance. Curve b in the same figure shows the potential distribution when the conductive layer is excluded. In this case, the capacitance is small, about 5 X I O-'F/rIf, so frictional charging with the transfer material Therefore, a potential difference of 2000 V or more is locally generated, which may cause toner scattering.

As explained above, in an image forming apparatus configured to guide the separated transfer material to the next process by a fixed guide member after transfer, the guide member is made of polyethylene, polyester, polyamide, polyimide, polytetrafluoride, etc. Thickness 0.5 selected from ethylene, polyfluoroethylene, etc.
4 mm or less (preferably 0.1 to 0.0 mm from the viewpoint of durability)
A guide member formed by superimposing a conductive layer selected from AM, iron, Sus, etc. on the inner layer as an outer layer of a film (between 54 mm) and a conductive layer selected from AM, iron, Sus, etc. is placed on the downstream side of the transfer charger, By applying a bias of 500 to 3000 V to prevent this from occurring, it is possible to prevent both image disturbance due to discharge and toner scattering due to frictional charging when the transfer material is conveyed.

FIG. 4 shows another embodiment of the guide member according to the present invention, in which parts corresponding to those of the above-mentioned device are denoted by the same reference numerals, and a description of their structure is omitted. do.

In this device, the conductive layer 7b of the guide member 7 and the shield of the transfer charger 3 are grounded via a constant voltage element or a load resistance 10 of IOMΩ or more, and the conductive layer 7b is
Apply a voltage of 0 to 2000v.

With this configuration, a strong positive electric field is generated from the transfer charger 3 to the guide member 7, and this is concentrated on the second static elimination needle 6, so that the static elimination efficiency of the static elimination needle is improved, and the first This eliminates the need for a static eliminating needle and also eliminates the need for a power source to bias the conductive layer, simplifying the configuration.

(3) Effects of the Invention As explained above, in an image forming apparatus that separates and conveys the transfer material using a static elimination needle after transfer, the guide member that guides the conveyance of the transfer material is insulated. The structure is extremely simple and compact because it has a multilayer structure consisting of a conductive layer and a conductive layer, and a bias is applied to the lid conductive layer.
It is possible to effectively prevent image disturbance due to discharge of the transfer material and scattering of toner due to charging of the guide member.

[Brief explanation of the drawing]

Figure 1 is a side view of essential parts showing an embodiment in which the present invention is applied to a copying machine equipped with a rotating cylindrical photoreceptor, and Figures 2 and 3 show potential distributions of the present invention and a comparative example, respectively. Graph and FIG. 4 are side views of essential parts showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 3... Transfer charger, 5... First static elimination needle, 6... Second static elimination needle, 7... Guide member, 7a.
- Middle insulating layer, 7b--conductive layer. Figure 2 Snow grain (V) Oyosho 1 Figure 3 Figure 4

Claims (1)

[Scope of Claims] An image forming apparatus that transfers an image on the surface of an image carrier to the transfer material by passing a sheet-like transfer material through a transfer site equipped with a transfer charger disposed close to the image carrier, A guide member for guiding the separated transfer material has a multilayer structure including an outer layer made of an insulating material and an inner layer made of a conductive material,
A transfer material guiding device characterized in that the thickness of the insulating outer layer is 0.54 mm or less, and a voltage having the same polarity as the transfer charge is applied to the conductive inner layer.