JPH02109079A - Transfer roller and transfer device for electrophotographic copying device - Google Patents

Abstract

PURPOSE:To prevent the dielectric breakdown of the surface layer of a transfer roller and to make the performance of cleaning for the transfer roller good by providing an elastic member layer on the circumference of the core bar of the roller and also providing a conductive resin layer on the outmost layer. CONSTITUTION:The transfer roller 4 is constituted of the core bar 1 whose outer circumference is covered with a conductive and elastic resin layer 2 and also whose outmost layer is provided with the conductive resin layer 3. As to the layer 2, the layer which keeps itself soft even if the moderate conductivity is given is used. This is the reason why a photosensitive body is easy to be hurt if the roller 4 is hard. Moreover, it is good to set up so that the specific resistance of the layer 3 may become equal or below 10 times as much as that of the layer 2. As stated above, since the outmost layer of the roller 4 is covered with the conductive resin layer, the performance of cleaning for the roller 4 can be improved and also the dielectric breakdown of the outmost layer can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transfer device for an electrophotographic apparatus, and in particular to a roller transfer device suitable for applying a bias voltage of opposite polarity to the toner to transfer a toner image onto paper. The present invention relates to a device and a transfer roller of a roller transfer device.

[Conventional technology]

Generally, when a toner image formed on a photoreceptor of an electrophotographic apparatus is transferred to paper, the transfer is performed by applying a voltage to the back surface of the paper to form an electric field. A conventional transfer roller uses a roller 4 in which a conductive elastic member 2 is provided around a roller core 1 and a highly insulating layer is provided thereon, and the toner is transferred by applying a high voltage to the conductive member 8. Images are being transferred. The conductive elastic member 2 described in ``2'' needs to have appropriate conductivity and low rubber hardness, and conductive additives such as carbon black or iTJ% agent are dispersed in the rubber or f4y! 1. It is made to be. However, it is difficult to set the resistance value of conductive elastic members with the above characteristics.
Due to resistance changes due to moisture absorption, plasticizer flow, and rills,
As shown in FIG. 2, a transfer roller has also been proposed in which a conductive layer and an elastic layer having separate conductive and elastic functions are provided instead of the conductive elastic member 2.

Incidentally, related devices of this type include, for example, Utility Model Application No. 53-]]2933g, and JP-A No. 53-7753.
3 can be mentioned. However, all of the above transfer rollers have thin outermost layers and cost $1! Due to the high insulating layer, there is a risk of dielectric breakdown in the highly insulating layer if the surface layer wears out due to long-term use or if metal particles contained in the developer are caught between the photoreceptor and the transfer roller. was not taken into account.

On the other hand, a roller without a highly insulating layer on the outermost layer has been devised, and without the highly insulating layer, the above-mentioned dielectric breakdown of the surface Jf'J can be prevented, but the toner adhering to the rubber surface of the transfer roller Even if an attempt was made to remove the stain using a cleaning means such as a brush, there was a tendency for it to become difficult to remove and cause stains on the back of the paper.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer roller and a transfer device that eliminate the above-described drawbacks of the prior art, prevent dielectric breakdown of the surface layer, and allow the transfer roller to be easily cleaned.

[Means to solve the problem]

The above object is achieved by providing an elastic member layer around the roller core metal and providing a conductive resin layer as the outermost layer.

[Effect]

Since the outermost layer of the transfer roller of the present invention is made of a conductive material, it is possible to reduce the potential difference acting on both sides of the surface layer during transfer, thereby preventing dielectric breakdown of the surface layer of the transfer roller. Furthermore, the surface of the rubber 11, which has high adhesiveness to the 1-ner, is coated with a resin layer, so that the transfer roll can be easily cleaned.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, the transfer roller 4 of the present invention has a core metal 1 whose outer periphery is covered with a conductive elastic layer 2 made of conductive rubber, conductive sponge, etc., and an outermost layer made of conductive resin. It is constructed by providing layer 3. The core metal is made of a metal such as stainless steel, aluminum, or iron, or a conductive member such as glass fiber, and a voltage is applied to one or both ends by contacting with a power supply member, such as a carbon brush or a bearing. The conductive elastic layer 2 usually contains conductive additives to impart appropriate conductivity, but still has softness (rubber hardness JI).
Use a rubber that can maintain a temperature of about 40 degrees SA or less, such as conductive silicone rubber, conductive urethane rubber, or a conductive sponge made of foamed conductive urethane. This is because if the transfer roller 4 is hard, it will damage the photoreceptor! This is because it makes it easier to move.

The conductive resin layer 3 is desired to have good toner releasability in order to improve the cleaning performance of the transfer roller 4, and to have good mechanical strength even if it is thinned to about 10 to 100 μm. Suitable materials for this include conductive fluororesin, conductive silicone resin, and conductive nylon.

The inventors have discovered that conductive polyimide and the like can be used. Furthermore, it has been found that the resistance value Rr between the unit surface (per square centimeter) of the transfer roller and the core metal is preferably about 1 x 10 δ to 5 x 10'' (Ω) in terms of toner transferability and pressure resistance of the photosensitive material. In other words, if the value is lower than this, the current during transfer will become large and the paper will be overcharged.This may cause damage to the photosensitive material, such as the paper wrapping around the photosensitive drum or disturbing the transferred toner image due to arc discharge. Further, if the resistance value is higher than the above value, it is necessary to set the voltage applied to the transfer roller 4 to be about 2000 V or even higher in order to obtain a predetermined transfer efficiency. This is because in the case of a photoreceptor with a relatively thin photoreceptor layer (approximately 30 μm or less) such as an organic photoreceptor or amorphous silicon, there is a risk that the photoreceptor layer will cause dielectric breakdown due to contact with the transfer roller 4. Because there is. Furthermore, in order to prevent dielectric breakdown of the conductive resin 3 during carrier entrainment, the electric field strength Es of the conductive resin layer 3 should not be extremely high compared to the electric field strength Ea of the conductive elastic layer 2 (1
) It is necessary to set it like the expression.

Es< 10 X Ea ・=(
1) Here, 5 Q is the thickness, R is the resistance per unit area, ρ
Let be the specific resistance.

Q s Q a Also, Rs”ρsQs, Ra=pa (because it is AG, (
Equation 2) is transformed into the following equation (3).

Rs< 10 X pa ・=(3
) Therefore, the specific resistance of the conductive resin layer 3 may be set to about 10 times or less the specific resistance of the conductive elastic layer 2.

As described above, according to this embodiment, since the outermost layer of the transfer roller is coated with a conductive resin layer, the transfer roller can be cleaned easily and dielectric breakdown of the outermost layer can be prevented.

3 and 4 show modified examples of the present invention 6. The difference from the embodiment shown in FIGS. 1 and 2 is that an insulating elastic layer 5 is provided on the outer circumference of the core metal 1 and the The point is that a conductive member 6 is provided at the end portion to provide conduction between the conductive resin layer 3 and the core metal 1. In such a configuration, the structure becomes complicated due to the provision of the conductive member 6, but since there is no need to add a conductive additive to the insulating elastic layer 5, the range of low hardness rubber materials that can be used is widened. There is an effect that a softer transfer roller 4 can be obtained compared to the example shown in FIG. 1.2.

The manufacturing method for forming the above-mentioned conductive resin layer 3 includes a method in which the conductive resin is liquefied with a solvent or the like and a coating treatment is applied to the surface of the conductive or insulating elastic layer, and a method in which the conductive resin is formed after forming one elastic layer. A method of covering the tube or a method of pouring liquid conductive rubber into a conductive resin tube can be applied. Moreover, the conductive resin WJ3 and the elastic layer 2,
A primer layer may be provided between the base plate and the base plate 5 to improve adhesion.

FIG. 7 shows another embodiment of the present invention, in which a transfer device 22 incorporating the transfer roller 4 of the present invention shown in FIGS. 1 to 4 is shown.
It shows. The transfer roller 4 is rotatably held by the transfer device frame 21 via a bearing. Further, in order to apply an appropriate pressing pressure to overlap the paper 17 with the photoreceptor 15, the pressure of the pressure spring 13 is transferred to an appropriate pressure transmission member 12.
is connected to the core metal 1 of the transfer roller 4. Further, a voltage supplied from a bias voltage g9 is applied to the core metal 1 by a carbon brush. In order to remove the toner 16 adhering to the transfer roller 4, a cleaning brush 18 and a scrubber 19 are arranged inside the transfer device 22, and the removed toner is sucked into the suction air 2o.
It is discharged together with In order to dissipate the electric charge accumulated in the cleaning brush 18, it is preferable that the tapping rod 19 be grounded and that the resistance between the surface of the cleaning brush 18 and the base be set to 106 to 1 QilΩ. This is because if the resistance value of the cleaning brush 18 is made too low, the bias voltage will leak and transfer performance will be impaired.

Further, the transfer device 22 is provided with a contact/separation mechanism for bringing the transfer roller 4 into contact with the photoreceptor 15 or pulling it away from the photoreceptor 15. The contact/separation mechanism includes a pivot 11, an arm 12, and a pressing spring 13. It consists of a solenoid 14 and the like, and is actuated by a predetermined sequence signal to cause the transfer roller 4 to approach and separate.

Regarding the additional resistance 10, the resistance R4 of the transfer roller 4
As mentioned above, it is not necessary to provide an additional resistor of 10 to 106 Ω if the resistance value of the transfer roller 4 is approximately 10 Ω or less and difficult to adjust.
It can be applied if you set it up.

FIG. 8 is a modification of FIG. 7, in which a sheet-like photoreceptor 26 is used as the photoreceptor and a photoreceptor winding drum 23 is used. When the photosensitive sheet 26 is wound up by the take-up roller 25 and the feed roller 24 after a predetermined printing page is completed, the solenoid of the contact/separation mechanism is operated to keep the transfer roller 4 separated from the photosensitive sheet 2G by a distance δ. This is accompanied by the effect of preventing damage to the surfaces of the photosensitive sheet 26 and the transfer roller 4 and peeling of the coating during winding.

FIG. 9 shows another embodiment of the present invention, in which a transfer device 22 of the present invention simultaneously transfers and prints two-color toner images by rotating a photoreceptor 151, and has a paper reversing mechanism capable of double-sided printing. This is an example applied to a color printer. Chargers 27 and 3 are installed around the photoreceptor 15 to create a two-color toner image.
0. An exposure device 28.31 and a developing device 29.32 are provided.

Further, behind the fixing device 37, there is a paper path switching valve 38, a reversing path 39. A switchback device 40 is provided to form a paper reversal mechanism. Further, a peeling corotron 33 is provided at the rear of the transfer device 22 to eliminate static electricity from the paper and peel it off from the photoreceptor.1 The transfer device 22 of the present invention can also be applied to such a double-sided printing two-color printer. 1) Even if wrinkles occur while the paper is being fed through the reversing path, transfer omissions can be prevented.

(2) There is also the effect that good transferability can be obtained even with two types of toners having different characteristics.

The transfer device according to the present invention can be used as a transfer device of a terminal printer device of a computer system, and can also be used as a transfer device of a recording device of a facsimile machine or a word processor. This makes it possible to improve the quality and prevent dielectric breakdown of the surface layer.

As mentioned above, when the present invention is applied to a transfer device of an electrophotographic apparatus, cleaning of the transfer roller is improved and stains on the back of the paper are prevented, and stains tend to occur when the transfer roller is used for a long period of time or when carriers are involved. This has the effect of preventing dielectric breakdown of the surface layer.

Further, the present invention provides a transfer member that is used for transfer by applying a bias voltage without being restricted by a transfer roller, for example,
It can also be applied to transfer belts, transfer drums of color recording devices, etc.

[Brief explanation of the drawing]

1 is a longitudinal cross-sectional view of one embodiment of the transfer roller of the present invention; FIG. 2 is a cross-sectional view of the embodiment of FIG. 1; FIG. 3 is a longitudinal cross-sectional view of another embodiment of the transfer roller of the present invention; Figure 4 is the fruit of Figure 3, W
FIGS. 5 and 6 are longitudinal sectional views of the conventional example, and FIGS. 7 to 9 are longitudinal sectional views of embodiments of the transfer apparatus of the present invention. ■ Core metal, 2 Conductive elastic layer, 3 Conductive resin base 54 Transfer roller, 5 Insulating elastic layer, 6
・Conducting part. 7... Insulating resin layer, 8... Conductive member 59/bias power supply, 10... Additional resistance, 11... Pivot 1-1
12...A1%, 13...Pressure spring, 14...Solenoid. 15... Photoreceptor, 16... Toner, 17... Paper,
18...cleaning brush, 19...beating stick, 2o...
Suction air, 21... Transfer device frame, 22... Transfer device, 23... Photosensitive sheet winding red drum, 24...
・Feeding roller, 25... Winding roller, 26・
- Sheet photoreceptor, 27... Charger, 28... Exposure device, 29... Developing machine, 30... Charger, 31...
- Exposure device, 32... Developing machine, 33... Peeling corotron, 34... Photoconductor cleaning brush, 35... Static eliminator, 36... Paper feed stunker 37... Fixing device, 38...
...Paper path switching valve, 39...Paper reversal path, 40.
...Switchback device. 1 day ago 10 Figure 8

Claims (1)

[Scope of Claims] 1. A transfer roller for an electrophotographic apparatus, characterized in that an elastic member layer is provided around the roller core metal, and a conductive resin layer is provided as the outermost layer. 2. Transfer of an electrophotographic apparatus, characterized in that the transfer roller according to item 1 and a roller cleaning means for cleaning the transfer roller are arranged, and a bias voltage is applied to the transfer roller to transfer a toner image onto recording paper. Device. 3. The transfer roller for an electrophotographic apparatus according to item 1, wherein the conductive resin layer is manufactured using a conductive resin tube. 4. The transfer roller for an electrophotographic apparatus according to item 1, wherein the conductive resin layer is manufactured by coating the elastic body with a liquid material in which a conductive resin is dissolved or dispersed in a solvent. 5. The transfer roller for an electrophotographic apparatus according to item 1, characterized in that the elastic member layer is made of conductive rubber. 6. The transfer of an electrophotographic apparatus according to item 1, characterized in that the elastic member layer is made of insulating rubber and is provided with a conductive means for electrically conducting between the conductive resin layer and the roller core metal. roller. 7. In item 1, the elastic body has a rubber hardness of 18 to 35.
A transfer roller for an electrophotographic device, characterized in that it is made of an elastic body of 100% (JISA). 8. In item 1, the resistance between the unit area (1 cm^2) of the pressing part of the conductive resin layer and the roller core metal is 1 x 10^
A transfer roller for an electrophotographic device, characterized in that the resistance is set to 8 to 5×10^9 (Ω). 9. The transfer device for an electrophotographic apparatus according to item 2, characterized in that the resistance between the roller cleaning means and the ground is 10^8 to 10^1^1 Ω. 10. The transfer device for an electrophotographic apparatus according to item 2, characterized in that a bias voltage of 500 to 1500 V is applied. 11. The transfer device for an electrophotographic apparatus according to item 2, characterized in that a resistor of 1 to 100 MΩ is connected between the roller core metal and the bias power source. 12. The transfer device described in item 2 has a photosensitive layer having a typical thickness of 30 μm.
1. A transfer device for an electrophotographic apparatus, characterized in that it is used in combination with a photoreceptor having a size of less than m. 13. The transfer device of an electrophotographic apparatus according to item 2, characterized in that the transfer device has a transfer roller contact/separation mechanism that separates the transfer roller from the photoreceptor. 14. The transfer device described in Items 2 and 13 is used in an electrophotographic apparatus having a photoreceptor of a photoreceptor sheet winding type, and the transfer roller is separated from the surface of the photoreceptor when the photoreceptor sheet is wound. A transfer device for an electrophotographic device, characterized in that: 15. A transfer roller and transfer device for an electrophotographic apparatus, wherein the transfer roller or transfer device described in items 1 to 14 is used as a transfer device for an optical printer, a copying machine, or a FAX. 16. A transfer roller and transfer device for an electrophotographic apparatus, wherein the transfer roller or transfer device according to items 1 to 14 is used as a transfer device for a double-sided printing optical printer and a double-sided printing copying machine. 17. A transfer roller and transfer device for an electrophotographic apparatus, wherein the transfer roller or transfer device described in items 1 to 14 is used as a transfer device for an optical printer for a computer terminal. 18. A transfer member for a color electrophotographic apparatus, characterized in that an elastic member layer is provided around a drum-shaped base and a conductive resin layer is provided as the outermost layer. 19. A transfer member for an electrophotographic apparatus, characterized in that an elastic member layer is provided on the outer periphery of a belt-shaped base body, and a conductive resin layer is provided as the outermost layer. 20. The transfer roller and transfer member according to item 1, item 18, or item 19, characterized in that the specific resistance of the conductive resin layer is set to about 10 times or less the specific resistance of the elastic layer. 21. The transfer roller and transfer member for an electrophotographic apparatus according to Items 1, 18, and 19, wherein the conductive resin layer is composed of at least a fluororesin and a conductive substance. 22. The transfer roller and transfer member for an electrophotographic apparatus according to Items 1, 18, and 19, wherein the conductive resin layer is composed of at least a nylon resin and a conductive substance.