JPS5810767A - Transfer device - Google Patents

Abstract

PURPOSE:To improve the carriability and to prevent the pollution due to a toner for transfer, by setting the volume resistivity of a transfer material guide member to 10<5>-10<10>OMEGAcm when a transfer paper is guided onto a photosensitive drum, where a developed image is formed, by the transfer material guide member. CONSTITUTION:A developed image 2 is formed on a photosensitive drum 1 (image carrier) by a developed image-forming means. A transfer corona discharger 3 is provided. Resistance material layers 6 where carbon is dispersed in polyethylene to have a volume resistance of 10<5>-10<10>OMEGAcm are provided on metallic transfer material lower and upper guide members 4 and 5, and these members are grounded. The photosensitive drum 1 is rotated in the direction of an arrow, and the developed image 2 is transferred to a transfer paper with corona discharge. Though a high voltage is generated in the transfer process by the corona discharge, guide members 4 and 5 prevent the transfer current with resistance material layers 6; and thus, the carriability of the transfer paper is improved, and the phenomenon of transfer failure and the pollution due to a toner are prevented effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer device, and more particularly to a transfer device that enables smooth transfer without staining the transfer material.

Conventionally, IIt formed on an image carrier such as an electrophotographic photoreceptor
A transfer device that guides a transfer material using a transfer guide member and transfers the transfer material to the transfer material sh by applying a transfer voltage is commonly used.

However, in this type of transfer device that applies a specific transfer voltage, the transfer current leaks through the transfer material guide member at high temperatures, resulting in poor transfer and failure.

As a countermeasure for this, there is the following 3m technology.

The first method is to electrically float the transfer material guide member.

If this method is used, even if the transferred member absorbs moisture at high temperatures, transfer omission will not occur, but the transfer current flows into the transfer guide member and charges the transfer guide member, which removes floating toner and toner on the latent image carrier. When the paper is wet, the friction between the transfer material and the transfer material guide member is also charged and causes the dirt. ing.

The second method is to apply a bias voltage to the transfer material guide member to prevent leakage of transfer current. This method also prevents transfer omissions in the same way as the previous method, but special
! ! do. For this reason, the device becomes IIH. Moreover, since a voltage is applied, safety measures for operator maintenance are required, which further complicates the apparatus.

j13#i, the transfer material guide member is grounded via a resistor.

If a sufficient resistance is selected to prevent transfer failure at high temperatures, the transfer current is more likely to accumulate and toner staining is more likely to occur as the potential reaches a level that causes toner adsorption.

Furthermore, if the surface of the transfer material guide member is made of metal, the conveyance of the transfer material may deteriorate at high temperatures.

The present invention has been made in view of the above-mentioned points, and provides a transfer device that enables good transfer. In a transfer device that guides a transfer material and transfers developed images onto the transfer material, the transfer material guide member has a volume resistance of 10'' to
It is characterized by being formed of a material with a capacity of 10"lJ-cm.

The details of the present invention will be explained below with reference to specific examples.
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The first factor is the side 1iia of the amount of transferred iron in the embodiment based on the present invention.
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A photosensitive drum is rotated in the direction of an arrow by a drive means (not shown).

Reference numeral 2 denotes developed images formed on the photosensitive drum by a latent image forming means and a developing means (not shown).

-3 is a transfer material discharger, 4 is a transfer material lower guide member made of metal, and 5 is a transfer material upper guide member also made of metal.

Reference numeral 6 denotes a resistive material layer provided on the surface of the lower transfer material guide member, and in the illustrated example, carmen is dispersed in high molecular weight polyethylene to give a volume resistivity of 1089·l.

Such a configuration allows good transfer to the transfer material 7 even in a high humidity environment (for example, 80 degrees RH).

Incidentally, the resistive material layer 6 is made of high molecular weight polyethylene without carbon dispersed therein (volume resistance of 1011JLoa or more).
When using a low tIk11A environment (e.g.
), the transfer material lower guide member 4 is charged by friction between the transfer material lower guide member 4 and the transfer paper 7. According to experiments, when the distance between the photosensitive drum 1 and the transfer material lower guide member 4 is 1.2 mm, the potential of the transfer material lower guide member reaches 11000 V or more.

However, when the voltage exceeds -500V, there is a torque on the tip of the guide member.
It was found that the toner adhered to the image on the next transfer paper and the back side of the leading edge of the image became smudged.It was also confirmed that the closer the potential was to OK, the less likely it was to become stained.90In this case, negative polarity toner was used. It is thought that the glass was charged with electricity due to exposure to the transfer material and adhered to the guide.0 Important At high temperatures, the corner current from the transfer corona discharger 6 passes through the low resistance transfer paper 7 to the transfer material lower guide member. If the guide is charged to 0 plus which has charged up the guide to +1000V or more, it is +700V.
As described above, it was found that the guide becomes dirty and the back side of the image becomes dirty.On the other hand, when a predetermined resistive material layer such as carbon-dispersed polymeric polyethylene is provided on the surface of the guide member 4 as in the above-mentioned odor body example device of the present invention, , the potential of the guide can be suppressed to within 1,300V at low temperatures and +500V even at high temperatures, and the guide will not become contaminated at all. However, it is sufficient to form a resistive material layer that suppresses the potential by -500V to +700VK.For practical use, the volume resistivity should be 10"g・1 or less, and preferably 108Ω・1 or less. On the other hand, it is inconvenient to make it smaller than 10'#-cm in practice in order to prevent transfer omissions.Then, it is preferably 10'?·α or more.

FIG. 2 is a side view illustrating another specific example of iron content based on the present invention. Components common to FIG. 1 are designated by numerals 11. In the apparatus shown in FIG. 2, a predetermined resistive material layer 6' is also provided on the transfer material contacting surface side of the transfer material upper guide member 5 to promote the certainty of transfer current leakage. Even when used for a period of time, it is possible to prevent the developer toner from adhering to the surface of the transfer material lower guide member 5. Therefore, it is possible to prevent the developer from spilling onto the front side of the transfer material.

Incidentally, as the above-mentioned resistive material, a material with additional teeth may be selected in consideration of the line separation property with the transfer material.

Furthermore, even if the material is originally an insulating material, a conductive material or a surfactant may be mixed therein to give it an appropriate volume resistance, as described above.

Further, in the illustrated example, the surface of the metallic guide member is coated with a resistive material layer, but it goes without saying that the guide member may be formed of a resistive material having an appropriate degree of breakage. Both of these are molded from high-polymer polyethylene mixed with carbon.

In this case as well, toner adhesion could be prevented even after long-term use, and toner contamination of the transfer material did not occur.

As the resin, in addition to high-molecular polyethylene, any material suitable for the purpose of the present invention may be used, such as polycarbonate and polypropylene.

As mentioned above from Gutai MK, the device of the present invention is excellent in that it does not cause toner adhesion and does not stain the transfer material even when used for a long time.

4Iliw's Easy I! Akira Figure 1 is a side view of a specific example transfer device based on the invention.

@Figure 2 is a side view of a modified iron amount based on the invention.

Fig. 3, further modification based on the present invention, iron amount side 1liI
It is III.

In the figure, 1: photosensitive drum (image carrier), 2: fi images,
3: Transfer corona discharger, 4.5: Transfer material (inner material), 6:
Resistive material layer 0 Applicant Canon Co., Ltd.

Claims (1)

[Claims] (1) In a transfer device that transfers MLtllk onto a transfer material by guiding a transfer material tube to a II carrier with developed images formed thereon by a transfer material guide member, the transfer material guide member has a volume resistance of 101 to 104 Ω. A transcription device O characterized by being formed with the ethics of