JPH11143249A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device equipped with a contact type sheet-like transfer device forming a uniform transfer current. SOLUTION: The transfer device 9 is constituted of a sheet-like member 21 and a supporting member 22 supporting the member 21. The member 21 is a nylon resin sheet and has the electric resistance value of 1×10<6> to 9×10<7> Ω because conductive carbon is dispersed in the sheet. The member 22 is constituted of an elastic PET film so that elastic force may be weak in the center part and it may be stronger and stronger toward both ends due to plural holes formed at different intervals or a circular-arc shaped edge the center part of which is recessed, and stuck the rear surface of the member 21 by using adhesive material 23 so as to elastically supporting the rear surface of the member 21. Thus, the leading edge of the member 21 being an extremely thin sheet rubs a transferring and carrying belt 1 with uniform pressing force, whereby the uniform transfer current is supplied to the belt 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a contact-type sheet transfer device for forming a uniform transfer current.

[0002]

2. Description of the Related Art Conventionally, there is an electrophotographic image forming apparatus. The image forming apparatus forms an electrostatic latent image on an image carrier by optical writing, converts the electrostatic latent image into a toner image, transfers the toner image to a sheet, and then fixes the toner image with a fixing device.

When the toner image is transferred onto paper, a corona discharger is used as a transfer unit so that sufficient transferability can be obtained even when the load of the system is changed due to environmental changes or the like. The corona discharger requires a relatively large current and is not only uneconomical in cost, but also increases the amount of ozone generated by the corona discharge in order to increase the processing speed, thereby polluting the working environment. In order to remove the ozone, a processing apparatus is required, which causes a problem that the apparatus is increased in size and cost is increased. For this reason, in recent years, various small-sized image forming apparatuses using a contact-type transfer device that does not rely on corona discharge are being put into practical use.

[0004] For example, a main part of such an image forming apparatus is constituted by a photosensitive drum, an initialization charging brush, a writing head, a developing device, a transfer brush and a cleaner along a circumferential surface of the photosensitive drum. You. The photoconductor drum has a photoconductor formed on its surface, is uniformly charged to a negative high potential by an initialization charging brush, is exposed by a writing head, and forms an electrostatic latent image corresponding to image information. You. The electrostatic latent image is formed into a toner image by a developing device, and the toner image is conveyed to a transfer unit where the photoconductor drum and the transfer brush are opposed to each other by rotation of the photoconductor drum, and is transferred onto a sheet by a transfer current from the transfer brush. Transcribed.

[0005] In recent years, in many cases, paper is conveyed to the transfer section by means of a transfer conveyer belt instead of conveying the sheet directly to the transfer section by a conveying roller. This is because the unstable state of the posture of the paper, such as the fluttering of the paper, which has been a problem when using the transport roller, is solved by using the transfer transport belt.

[0006]

By the way, the transfer current applied from the transfer unit to the sheet is effected through the transfer / transport belt, and is affected by the electrical characteristics of the transfer / transport belt.

Further, the above-mentioned transfer brush has a drawback that the electric resistance varies from place to place and is easily stained. However,
Since the transfer roller has a problem that the entire apparatus becomes large, a transfer sheet has been attracting attention in recent years.

However, the transfer sheet has a problem in electric resistance characteristics, and it can be said that various methods for supplying a stable transfer current are still being sought. The object of the present invention is to
An object of the present invention is to provide an image forming apparatus including a contact-type sheet transfer device that forms a uniform transfer current.

[0009]

The structure of the image forming apparatus of the present invention will be described below. First, the image forming apparatus according to the first aspect of the present invention provides an image carrier, a toner image forming unit that forms a toner image on the image carrier, and the image formed by the toner image forming unit. A transfer conveyance belt that adsorbs the transfer material on the outer peripheral surface thereof so as to contact the transfer material with the carrier, and that is circulated and moved inside the transfer conveyance belt; A sheet-shaped transfer device for transferring the toner image onto the transfer material by pressing the transferred transfer material against the image carrier via the transfer-conveying belt, and a transfer power for supplying power to the sheet-shaped transfer device An image forming apparatus including a supply unit, wherein the transfer conveyance belt is formed by mixing a conductive agent in an ethylene tetrafluoroethylene copolymer, and has a surface resistance value of 1 × 10 ^{11 to} 9 × after energization. 10 and ^{12 Ω} / cm mouth Set so that, the sheet transfer device, a resin sheet member and the resin sheet made by mixing a conductive agent composed of a support means for supporting, the resistance of the resin sheet member 1 × 10 ⁶ ~ 9x
It is configured by setting to 10 ⁷ Ω.

Next, an image forming apparatus according to a second aspect of the present invention provides an image carrier, a toner image forming means for forming a toner image on the image carrier, and a toner image forming means using the toner image forming means. A transfer conveyance belt that adsorbs the transfer material on the outer peripheral surface thereof so that the transfer material comes into contact with the image carrier, and is circulated and disposed inside the transfer conveyance belt in a circulating movement direction; A sheet-shaped transfer device that presses the transfer material conveyed by the transfer conveyance belt onto the image carrier through the transfer conveyance belt to transfer the toner image onto the transfer material; and supplies power to the sheet-shaped transfer device. An image forming apparatus comprising: a transfer power supply unit for supplying the sheet-like transfer device, wherein the sheet-like transfer device includes a resin sheet member mixed with a conductive agent and a support unit for elastically supporting a back surface of the resin sheet member. Make up the above resin sheet 1 the tip of the member than the supporting means
mm or more.

The resin sheet is made of, for example, a nylon resin. Further, the support means is made of an elastic support sheet laminated on the back surface of the resin sheet member, for example. And
The elastic support sheet may be, for example, P
It consists of ET resin.

In any of the above image forming apparatuses, for example, the pressing force of the sheet-like transfer device on the transfer / transport belt gradually changes along the direction of circulation of the transfer / transport belt. It is provided with a vertical direction changing means for changing the elastic force of the support means. Further, for example, the elastic force of the supporting means is changed so that the elastic supporting force of the sheet-like transfer device to the resin sheet member gradually changes in a direction orthogonal to the circulating movement direction of the transfer-conveying belt. It comprises a width direction changing means for changing.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view schematically illustrating a configuration of a main part of a tandem-type color image forming apparatus according to an embodiment. In the color image forming apparatus shown in FIG. 1, a transfer / conveyance belt 1 is disposed in the center of the apparatus in a flat loop shape in the front-rear direction, and both ends of the loop in the horizontal direction are held by a driving roller 2 and a driven roller 3. ing.

The transfer conveyor belt 1 is prepared by mixing a conductive agent into ETFE (ethylene tetrafluoroethylene copolymer), forming the film into a film having a thickness of about several hundred μm, and having a surface resistance value of 1 × after energization. It is set to be 10 ^{11 to} 9 × 10 ¹² Ω / cm. As a result, it is possible to stabilize the electric resistance value at the initial stage by performing predetermined energization. It has been found through experiments that the above-mentioned electric resistance value is a resistance value capable of exhibiting the most stable transferability to various types of paper.

The transfer transport belt 1 is driven by a driving rotary roller 2 and circulates in a counterclockwise direction indicated by an arrow A in the figure. In the upper circulating portion of the transfer conveyance belt 1,
Four photosensitive drums 4 (4a, 4b, 4
c, 4d) are arranged in a multi-stage manner in the paper transport direction (from right to left in the figure).

The photosensitive drum 4 is formed by uniformly applying a photoconductor to the surface of a conductive metal roller. Although not shown, the metal roller is grounded. Each of these photoconductor drums 4 is surrounded (hereinafter, only the devices around the photoconductor drum 4d are numbered and shown), a cleaner 5, an initialization charging brush 6, a writing head 7, a developing device 8 and a transfer unit 9 with the transfer and conveyance belt 1 interposed therebetween. Each of the four developing devices 8 from the developing device corresponding to the most upstream photosensitive drum 4a to the developing device corresponding to the most downstream photosensitive drum 4d has therein three subtractive primary colors, yellow (Y), The non-magnetic toner of magenta (M) and cyan (C) and the non-magnetic toner of black (Bk) dedicated to the black portion of the image are stored, respectively. At the lower openings of these developing devices 8, developing rollers 11 are provided.
Are rotatably supported. The developing roller 11 is supplied with a developing bias from a power supply (not shown),
Is pressed against.

The initialization charging brush 6 is connected to a high-voltage power supply (not shown) and applies a negative high voltage to the photosensitive drum 4.
To make the peripheral surface photosensitive layer of the photosensitive drum 4 have, for example, “−”.
650 V (volts) ". The writing head 7 is provided with a laser light source or an LED light source, and
Is selectively exposed according to image information. By this exposure, the potential on the surface of the photosensitive drum 4 becomes substantially “−70”.
V, a negative low-potential portion attenuated is formed.
70V "and the above-mentioned" -650 "which has been initialized and charged.
Thus, an electrostatic latent image composed of a high potential portion substantially maintaining V ”is formed.

The developing roller 11 of the developing device 8 has, for example, "-
250V "is applied. The toner in the developing device 8 is stirred by a stirrer 12 disposed in the developing device 8, charged to a weak negative potential by rubbing with a supply roller 13, supplied to the peripheral surface of the developing roller 11, and regulated by a regulating blade. The layer 14 is regulated to a constant layer thickness and adheres to the surface of the developing roller 11.

The toner is conveyed to the portion facing the photosensitive drum 4 while the developing roller 11 rotates. Developing roller 1
1 and the photosensitive drum 4, the above-mentioned “−70 V”
Between the low potential portion of the electrostatic latent image of FIG.
80V "potential difference is formed. That is, the low potential portion of the electrostatic latent image forms a positive potential relative to the developing roller 11. Due to this potential difference, the non-magnetic toner charged to the negative polarity is transferred to the low potential portion of the electrostatic latent image of the positive polarity of the photosensitive drum 4 to form a toner image (reversal development). This toner image is conveyed to the opposing portion between the photoconductor drum 4 and the transfer device 9 by the rotation of the photoconductor drum 4.

A sheet 15 as a transfer material is adsorbed and conveyed to the transfer / conveyance belt 1 at an opposing portion (transfer portion) between the photosensitive drum 4 and the transfer device 9. The paper 15 is taken out one by one from a paper cassette or the like (not shown) and fed, and is supplied to the upstream end portion of the transfer / transport belt 1 by a supply device such as a pair of standby rolls in synchronization with printing timing. A suction roller 16 is disposed at an upstream end of the transfer conveyance belt 1, and the suction roller 16 is pressed against the driven roller 3 via the transfer conveyance belt 1 to give a positive charge to the paper 15 and 15 is electrostatically attracted to the transfer / conveying belt 1. As a result, the paper 15 is transported in a stable state (posture) in the upper circulation section of the transfer transport belt 1.

A transfer unit 9, which will be described in detail later, is connected to a positive power supply (not shown), and applies a positive transfer bias via the transfer conveyance belt 1 to the photosensitive drum 4 and the transfer unit 9.
Is applied to the sheet 15 conveyed to the portion opposite to. As a result, the negative toner image on the photosensitive drum 4 is transferred to the paper 15 having a positive potential.

The paper 15 onto which the toner image has been transferred is separated from the transfer / transport belt 1 by a separation claw 17 whose leading end is in contact with the surface of the transfer / transport belt 1 at the downstream end in the transport direction, and is located downstream thereof. The sheet is carried into the fixing unit 18. The fixing unit 18 includes a heat roller, a pressure roller, and the like surrounded by a heat insulating plate. The toner image on the sheet 15 is thermally fixed on the paper surface while the paper 15 is held and transported by the rotating heat roller and the pressure roller. Then, the paper 15 on which the toner image is fixed is discharged out of the apparatus.

FIG. 2A is an enlarged view of the transfer portion.
FIG. 2B is a diagram showing the configuration of the transfer device 9. Figure (b)
Is composed of a sheet-like member 21 and a support member 22 for supporting the sheet-like member 21. In the present embodiment, the sheet-shaped member 21 is made of a nylon resin as a material, and carbon is dispersed as a conductive agent. This conductive nylon-based resin is formed in a sheet shape, and is set so that the electric resistance value is 1 × 10 ^{6 to} 9 × 10 ⁷ Ω.

The amount of carbon dispersed in the resin is
In the case of a nylon-based resin, carbon is “3” to “30” with respect to resin “100” in weight ratio. If the amount of carbon is further increased, it becomes difficult to uniformly disperse the carbon, and a collection portion of carbon is formed in some places, a locally low electric resistance portion is developed, and the carbon becomes unusable. . On the other hand, if the electric resistance is set to 10 ⁷ Ω or more, the amount of carbon is too small. In this case, it is difficult to uniformly disperse the carbon, and a locally high electric resistance is formed. After all, it will not be usable.

Next, the supporting member 22 is made of a resilient PET.
It is made of a film, is adhered to the back surface of the sheet member 21 using an adhesive material such as an adhesive or a double-sided tape, is laminated on the sheet member 21, and elastically supports the sheet member 21 from the back surface.

The transfer device 9 is provided with a support member 2 on the back side.
The lower end of the transfer device supporting member 2 is connected to the lower end of the transfer device supporting member 2 as shown in FIG.
4 is adhered to and supported by a support portion having a cross section at the tip end formed in a laterally oblique T-shape. This transfer device support member 2
One end of a conductive tape 25 is adhered to the lower end of the sheet-like member 21 which is the surface side of the transfer device 9 adhered and supported at the tip of the transfer tape 4, and the other end of the conductive tape 25 is The support member 24 is attached to the lower surface of the transfer device support member 24 by wrapping around the lower part of the oblique T-shape in the horizontal direction, and a wiring 26 for supplying a transfer current is connected to the portion attached to the lower surface.

The inclination of the laterally oblique T-shaped support portion of the transfer device support member 24 is perpendicular to the vertical line (perpendicular line from the back surface of the upper circulating portion of the transfer conveyance belt 1) in the circulating movement direction of the transfer conveyance belt 1. It is formed with an inclination of 35 ° on the side (the direction indicated by arrow B in the figure). As a result, the transfer device 9 is disposed at a 35 ° inclination on the downstream side in the circulating movement direction of the transfer conveyance belt 1.

The transfer unit 9 has a transfer and conveyance belt 1
The length is set such that the leading end thereof is 4 mm higher than the transfer surface of the transfer transfer belt 1 in a free state where no bending pressure is applied due to rubbing. Then, as shown in FIG. 2A, the transfer unit 9 is in a state of rubbing the transfer conveyance belt 1 and the rubbing portion is a contact portion between the photosensitive drum 4 and the transfer conveyance belt 1. It is arranged to be located directly below.

FIG. 3A is a view showing a method of measuring and testing the resistance value of the transfer unit 9 in the present embodiment, and FIG.
FIG. 4 is a diagram showing the results of the measurement test. As shown in FIG. 3A, the wiring 26 connected to the conductive tape 25
A 100 V DC power supply 27 is connected. Then, using a bar-shaped metal gauge 29 having one end connected to the resistance meter 28, the tip of the sheet-like member 21 of the transfer unit 9 is pressed from the one side end to the other side end while being pressed. Rub on the part. This is repeated several times, and the resistance value indicated on the resistance meter 28 is checked.

In FIG. 3B, the vertical axis represents the electric resistance value (MΩ: megaohm), and the horizontal axis represents the length in the width direction from the one side end to the other side end of the sheet-like member 21. Is shown. As shown in the figure, it can be seen that the distribution 31 of the measured electric resistance values is almost uniformly distributed. As described above, the transfer device 9 according to the present embodiment has extremely good electric resistance characteristics.

By the way, generally, the sheet-like member 2
As shown in FIG. 2A, when an extremely thin sheet member as shown in FIG. 1 is bent and pressed against a flat surface such as the transfer / conveying belt 1, the bending resistance at the edge of the sheet member against this bending pressure ( The stress acts strongly at the central portion having spread on both sides, and works weakly at both ends without spreading outward.

The same applies to the sheet-like member 21 of the transfer unit 9, and the bending resistance, that is, the pressing force on the transfer / transport belt 1 is strong at the center and weak at both ends. The pressing area in such bending pressing is proportional to the pressing force. In other words, the pressing area is different between the central portion and the both end portions, and the pressing area becomes uneven as a whole. If the pressing area is uneven, the current applied to the pressing partner, ie, the transfer current applied to the transfer conveyance belt 1, becomes uneven.

FIGS. 4A and 4B are views showing the structure of the transfer unit 9 in which the bending pressure of the sheet-like member 21 is constant at the center and both ends. In the transfer device 9 'shown in FIG. 9A, a plurality of inverted triangular holes 22-1 are provided in a support member 22 attached to the back surface of a sheet member 21. The plurality of holes 22-1 are
The interval is narrower toward the center and wider at the ends. As a result, the elastic supporting force of the support member 22 is formed to be weaker toward the center and stronger toward both ends.

As described above, the sheet-like member 21 of the transfer device 9
The elastic force of the supporting member 22 is changed so that the elastic supporting force of the supporting member 22 gradually changes in a direction orthogonal to the direction of circulating movement of the transfer conveyance belt 1. The supporting force is strong at the center of the above-mentioned sheet-like member 21 and neutralized with a weak bending pressure at both ends,
As for the transfer device 9, the pressing force can be obtained uniformly at the center portion and both end portions, and the unevenness of the transfer current described above is eliminated.

FIG. 3 (b) shows that, instead of providing a hole in the support member 22, the shape of the upper edge is formed in an arc shape that is concave at the center and elastic at the center and both ends. The bearing capacity is different. The elastic support force on the sheet-like member 21 is weak at the center where the edge of the support member 22 is a concave bottom, and the elastic support force on the sheet-like member 21 is strong at both ends which are the ends of the concave arc. work. Also in this case, the elastic supporting force that gradually changes in the width direction of the support member 22 is neutralized by the strong bending pressure at the center of the sheet-like member 21 and the weak bending pressure at both ends, and the transfer device 9
As a result, the pressing force can be obtained uniformly at the center and both ends, and the unevenness of the transfer current is eliminated.

By the way, in such a sheet-like transfer device, if the bending resistance with the transfer / transport belt is too strong, a problem occurs in the sheet conveyance of the transfer / transport belt. Fig. 7 (a), (b)
Is a diagram showing such a defect. FIG. 3A shows a state in which the tip of the sheet-like transfer device a has a strong bending resistance, and the transfer conveyance belt b is lifted up along the peripheral surface of the photosensitive drum c downstream of the transfer portion. I have. Also, FIG.
The figure shows a state in which the frictional resistance of the rubbing surface is increased due to the large bending resistance of the sheet-like transfer device a, and the transfer conveyance belt b is waving on the upstream side of the transfer portion. In any case, unevenness occurs in the conveyance of the sheet, and therefore, the formed image is also uneven, thereby deteriorating the image quality. Hereinafter, a transfer device that solves such a problem will be described.

FIG. 5 (a) is a view showing the structure of a sheet-like transfer device according to another embodiment, and FIG. 5 (b) is a side view in which the transfer device is attached to a transfer device support member. (c) is a diagram showing an engaged state of a transfer unit using the sheet-shaped transfer device. As shown in FIG.
Is made of the same material as that of the sheet member 21 as shown in FIG. 2B and the same material as the support member 22 of FIG. Only the support member 36 is slightly shorter. The length of the support member 36 is formed such that the tip is shorter than the tip of the sheet-shaped member 21 by X mm. The length set to this Xmm is 1 mm or more. This is disposed on the transfer device support member 24 as shown in FIG. 5B, as in the case of FIG. 2A. FIG. 5 (b) shows the conductive tape 2 shown in FIG. 2 (a).
5 is omitted.

This sheet-like transfer device 35 is bent and pressed against the transfer portion, and the tip of the support member 36 is contacted between the photosensitive drum 4 and the transfer / transport belt 1 (actually, as shown in FIG. 5C). (A tangent parallel to the axis of the photosensitive drum 4). As described above, the support member 36 only presses the sheet-like member 21 against the transfer / conveyance belt 1 in a narrow range of the leading end, and does not mean that the supporting member 36 presses the sheet-like member 21 in a wide range of the leading end as shown in FIGS. Since there is no transfer conveyor belt 1, there is no problem that the transfer conveyance belt 1 is lifted downstream or wavy upstream. Even if the supporting member 36 for pressing the sheet member 21 against the transfer / conveying belt 1 is so short, the supporting member 36 is not as strong as the supporting member 36 but is 1 mm larger than the supporting member 36 of the sheet member 21 having bending elasticity. Since the long end forms a wide contact surface with the transfer conveyance belt 1, a sufficient transfer current to be applied to the transfer conveyance belt 1 can be maintained.

As described above, by forming the sheet-like transfer device so that the pressing force of the sheet-like transfer device against the transfer / transport belt gradually changes along the circulating movement direction of the transfer / transport belt, the transfer due to too strong pressing is performed. A sufficient transfer current can be applied to the transfer / transport belt without causing a problem in the transportability of the transfer belt.

FIGS. 6 (a), 6 (b) and 6 (c) show sheet-like sheets formed such that the pressing force on the transfer / transport belt gradually changes along the direction of circulation of the transfer / transport belt as described above. FIG. 9 is a diagram illustrating another example of the transfer device. FIG. 7A shows the sheet-like member 21.
The supporting members 37 and 38 for supporting the sheet-like member 21 are sequentially formed with the leading ends thereof being shortened, whereby the pressing force of the supporting members 37 and 38 for supporting the sheet-like member 21 gradually changes along the circulating movement direction of the transfer conveyance belt. FIG.

FIG. 4B shows that one supporting member 39 for supporting the sheet-like member 21 is formed so as to become thinner toward the leading end, whereby the supporting member for supporting the sheet-like member 21 is formed. An example is shown in which the pressing force of No. 39 is formed so as to gradually change along the circulating direction of the transfer conveyance belt.

FIG. 3C shows that the sheet-like member 40 itself without the support member attached thereto is formed so as to become thinner toward the front end, and is directly attached to the transfer device support member 24. Thus, an example is shown in which the pressing force of the transfer unit is formed so as to gradually change along the circulating movement direction of the transfer conveyance belt.

[0043]

As described above in detail, according to the present invention, a sheet-like rubbing member having a fixed electric resistance is formed with different elasticity so that it becomes weaker at the center and gradually becomes stronger toward both ends. The transfer section is supported by the elastic sheet member provided, and a uniform transfer current in the width direction can be applied to the transfer conveyance belt. Therefore, a high-quality image can be formed with a small apparatus. . In addition, since the sheet-like rubbing member having a fixed electric resistance value is similarly supported by the elastic supporting member formed so that the elasticity gradually becomes weaker toward the rubbing end, the rubbing member is disposed in the transfer portion. It is possible to apply a sufficient transfer current to the transfer / transport belt with a large rubbing area without causing any trouble in the transfer / transport belt with an excessively strong pressing force. Therefore, it is possible to form and transfer a high-quality image with a small apparatus. It is possible to provide a color image forming apparatus in which no trouble occurs.

[Brief description of the drawings]

FIG. 1 is a side sectional view schematically illustrating a configuration of a main part of a tandem type color image forming apparatus according to an embodiment.

FIG. 2A is an enlarged view of a transfer unit of a color image forming apparatus,
(b) is a diagram showing a configuration of the transfer device.

FIG. 3A is a diagram illustrating a method of a measurement test of a resistance value of a transfer device according to an embodiment, and FIG. 3B is a diagram illustrating a result of the measurement test.

FIGS. 4A and 4B are diagrams showing a configuration in which the bending pressure of the sheet-like member of the transfer device according to one embodiment is constant at the center and both ends.

5A is a diagram showing a configuration of a sheet-like transfer device according to another embodiment, FIG. 5B is a side view of the sheet-like transfer device attached to a transfer device support member, and FIG. FIG. 6 is a diagram illustrating an engagement state of a transfer unit using a device.

FIGS. 6 (a), (b) and (c) are views showing a modification of the sheet transfer device.

FIGS. 7 (a) and 7 (b) are diagrams showing problems with a transfer conveyance belt due to strong bending resistance by a conventional sheet-like transfer device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transfer conveyance belt 2 Drive roller 3 Follower roller 4 (4a, 4b, 4c, 4d) Photoconductor drum 5 Cleaner 6 Initialization charging brush 7 Writing head 8 Developing device 9, 9 ', 9 "Transfer device (one embodiment) 11) developing roller 12 stirrer 13 supply roller 14 regulating blade 15 paper 16 suction roller 17 separation claw 18 fixing portion 21 sheet member 22 support member 22-1 hole 22-2 edge 23 adhesive material 24 transfer device support member 25 conductive Tape 26 Wiring 27 DC power supply 28 Resistance meter 29 Metal gauge 31 Resistance distribution 35 Transfer unit (other embodiments) 36, 37, 38, 39 Supporting member 40 Sheet member

Claims (7)

[Claims] An image carrier, a toner image forming means for forming a toner image on the image carrier, and a transfer material for contacting the image carrier on which a toner image has been formed by the toner image forming means. A transfer conveyance belt that adsorbs the transfer material on the outer peripheral surface and circulates, and the transfer material that is disposed inside the transfer conveyance belt and that is inclined in the circulation movement direction and transfers the transfer material conveyed by the transfer conveyance belt; An image forming apparatus comprising: a sheet-shaped transfer device that transfers the toner image onto the transfer material by pressing the image carrier through a conveyance belt; and a transfer power supply unit that supplies power to the sheet-shaped transfer device. The transfer / conveying belt is formed by mixing a conductive agent in an ethylene tetrafluoroethylene copolymer so that the surface resistance after energization is 1 × 10 ^{11 to} 9 × 10 ¹² Ω / square cm. Set to the sheet The transfer unit, constituted by formed by mixing a conductive agent and a resin sheet member and the support means for supporting the resin sheet,
The resistance value of the resin sheet member is 1 × 10 ^{6 to} 9 × 10 ⁷
An image forming apparatus characterized by being set to Ω. 2. An image carrier, a toner image forming means for forming a toner image on the image carrier, and a transfer material contacting the image carrier on which a toner image has been formed by the toner image forming means. A transfer conveyance belt that adsorbs the transfer material on the outer peripheral surface and circulates, and the transfer material that is disposed inside the transfer conveyance belt and that is inclined in the circulation movement direction and transfers the transfer material conveyed by the transfer conveyance belt; An image forming apparatus comprising: a sheet-shaped transfer device that transfers the toner image onto the transfer material by pressing the image carrier through a conveyance belt; and a transfer power supply unit that supplies power to the sheet-shaped transfer device. Wherein the sheet-like transfer device comprises a resin sheet member mixed with a conductive agent and supporting means for elastically supporting a back surface of the resin sheet member, and a tip of the resin sheet member is supported by the supporting means. Less than 1mm An image forming apparatus characterized in that is protruded. 3. The image forming apparatus according to claim 1, wherein the resin sheet is made of a nylon resin. 4. The image forming apparatus according to claim 1, wherein said support means comprises an elastic support sheet laminated on a back surface of said resin sheet member. 5. The image forming apparatus according to claim 4, wherein said elastic support sheet is made of PET resin. 6. A longitudinal elastic force changing means for changing an elastic force of said supporting means so that a pressing force of said sheet transfer device against said transfer / conveying belt gradually changes along a circulating movement direction of said transfer / conveying belt. The image forming apparatus according to claim 1, further comprising: 7. A width direction elastic force that changes the elastic force of the support means so that the elastic supporting force of the sheet-like transfer device on the resin sheet member gradually changes in a direction orthogonal to the circulating movement direction of the transfer conveyance belt. 3. The image forming apparatus according to claim 1, further comprising a change unit.