JPH08234588A - Image forming device and transfer device - Google Patents

Abstract

PURPOSE: To provide a transfer device and an image forming device capable of obtaining the image of higher quality, by reducing an inrush action force into a gripper of a transfer material, and eliminating a mechanical inference to a latent image forming as well as the transferred image thereby. CONSTITUTION: A transfer drum 3A is provided with a gripper 3f equipped with an upper pawl 37 for gripping to hold a leading end of the transfer material 2 pressing from its upper part. The butting face 36c, to which the leading end of the transfer material 2 butts, formed in the gripper 3f, is formed in a state of more protruding the lower side of the upper pawl 37 than another section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system or an electrostatic recording system in which a visible image formed on an image carrier is transferred onto a recording material conveyed by a transfer device to obtain an image. The present invention relates to an image forming apparatus and a transfer apparatus such as a copying machine and a laser beam printer, which can stabilize a high quality multicolor image particularly when embodied in a color image forming apparatus and a transfer apparatus used therein. Can be obtained.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus, the same recording material usually carried and conveyed by a transfer device having a transfer drum,
That is, there is a so-called multiple transfer type electrophotographic color copying machine or color printer that obtains a color image by transferring a plurality of visible images (toner images) of different colors onto a transfer material. In such an image forming apparatus, for example, as shown in FIG. 1, the transfer material 2 fed from the feeding unit 1 is gripped at the tip of the transfer material 2 by a gripper 3f provided on the transfer drum 3A. The sheet is conveyed to the outer periphery of the transfer drum 3A, the transfer step is performed, and after the transfer step is completed, it is separated from the transfer drum by the separating means 40 and is conveyed to the fixing and sheet discharging steps.

The transfer drum comprises cylindrical flanges 31 arranged on both sides, as will be understood with reference to FIG.
It has a drum cylinder 32 arranged between both flanges 31. The drum cylinder 32 is provided with a gripper 3f that holds the tip of the transfer material. The transfer drum is
It can be rotated around the central axis 3e in the arrow direction (clockwise direction) in FIG.

FIG. 3 shows a conventional gripper 3f.
The gripper 3f has a gripper main body 33 having a substantially rectangular cross section, and a C-shaped mounting portion 34 is formed at both ends of a side surface 36a along the longitudinal direction of the gripper main body 33. To be done. The gripper 3f is attached to the pivot shaft 35 provided on the transfer drum 3A via the attachment portion 34. The gripper 3f is, for example, a spring S.
(FIG. 4) or the like, it is constantly urged toward the center of the transfer drum 3A.

The pivot shaft 35 is integrally attached to an actuating lever 35 extending inward in the radial direction of the transfer drum 3A, as shown in FIG. When the actuating lever 35 is swung in the arrow direction by the driving means 50 such as an electromagnetic solenoid, the pivot shaft 35 is also swung in the same direction. As a result, the gripper 3f swings between the closed position for holding the transfer material 2 (the position indicated by the alternate long and short dash line in FIG. 4) and the open position for receiving or releasing the transfer material (the position indicated by the solid line in FIG. 4). To do.

Further, the other side surface 36b of the gripper main body 33
Forms an abutting surface against which the tip of the transfer material 2 fed to the transfer drum 3A abuts, and the upper surfaces of both ends thereof cooperate with the transfer material carrying surface of the transfer drum 3A when the gripper 3f is closed. Upper claw 37 that presses the upper end of the tip of the transfer material 2
The lower claw 38 is formed on the lower surface of the lower surface of the transfer material 2 to push the transfer material 2 outward from the surface of the transfer drum when the gripper 3f is opened.
Therefore, the abutting surface 36b of the gripper body 33, the upper claw 3
A concave portion for receiving the transfer material 2 is formed by 7 and the lower claw 38.

Thus, the conventional gripper 3 having the above structure
At f, when the transfer material 2 fed from the feeding unit 1 is gripped by the gripper 3f, the abutting surface 3 of the gripper 3f.
It was shaped so as to hit the entire width of 6b.
Further, when the transfer material 2 fed from the feeding unit 1 is gripped by the gripper 3f, the tip of the transfer material is abutted against the gripper surface 36b.
In order to ensure that the leading edge of the image writing is aligned, the pushing amount of the transfer material, that is, the so-called loop amount at the time of abutting, is 1.5 mm to 2.5 mm. The delivery was controlled.

[0008]

However, in the conventional apparatus, as shown in FIG. 4, when the transfer material 2 fed from the feeding portion 1 is rushed into the gripper, the tip of the transfer material is placed on the entire abutting surface of the gripper 3f. Upon impact, the shock affects the latent image formation, and further, at the transfer position T, the transfer material 2
In some cases, the toner image transferred to was disturbed. Also, due to the large loop amount, the acting force on the gripper increases, and the shock may affect the image.

On the other hand, if the gripper 3f is contaminated due to toner scattering in the image forming apparatus or due to toner scattering during cleaning of the transfer drum, if toner adheres to a portion other than the back side of the upper claw 37 of the gripper. , The tip of the transfer material might hit the part, resulting in edge contamination.

Therefore, an object of the present invention is to minimize the area of the transfer material abutting surface of the gripper, to provide a cushioning material on the surface of the gripper against which the transfer material abuts, or to the gripper of the transfer material. By reducing the amount of plunge of the transfer material, and further by forming the loop of the transfer material at the time of the gripper plunge, the force of the transfer material to plunge into the gripper is reduced, thereby forming a latent image and a transferred image. To provide a transfer device and an image forming apparatus capable of obtaining a higher quality image by eliminating the mechanical influence of the above.

Another object of the present invention is to provide a transfer device and an image forming device capable of preventing the tip portion of the transfer material from being soiled and obtaining a higher quality image.

[0012]

The above object can be achieved by a transfer device and an image forming apparatus according to the present invention. In summary, according to the first invention, a latent image is formed on an image carrier,
In the image forming apparatus, the latent image is developed into a visible image, and the visible image is transferred onto a transfer material carried on a transfer material carrying surface of a transfer device to obtain an image. Has a gripper having a claw for pressing and gripping the tip of the transfer material from above, and the abutting surface of the gripper against which the tip of the transfer material fed to the transfer device abuts is the claw. There is provided an image forming apparatus characterized in that a lower part of the lower part is formed to be more convex than the other part. This image forming apparatus forms a latent image corresponding to each color component on an image carrier, develops the latent image with a developer corresponding to each color component to form a visible image, and the visible image is A color that forms a multicolor image by superposing and transferring on a transfer material that is carried by a transfer device and conveyed can be used as an image forming device.

Preferably, the transfer device includes a transfer drum which provides a transfer material carrying surface, and the gripper is provided on the transfer drum. According to one embodiment of the present invention, an elastic member made of sponge or rubber is provided on the lower surface of the claw on the abutting surface of the gripper. Also, preferably,
When the front end of the transfer material fed to the transfer device is abutted against the abutting surface of the gripper, the pushing amount is 0 to
The length of the transfer material is 1.5 mm, and a loop of the transfer material is formed on the lower side when the front end of the transfer material fed to the transfer device abuts against the abutting surface of the gripper.

According to the second aspect of the invention, in a transfer device which carries and conveys the transfer material in order to transfer the visible image formed on the image carrier to the transfer material, the tip of the transfer material is placed above the transfer material. The gripper is provided with a claw for holding and gripping the gripper, and the abutting surface of the gripper against which the tip of the transfer material fed to the transfer device abuts has a lower part of the claw than other parts. Provided is a transfer device characterized by being formed in a convex shape.

Preferably, the transfer device comprises a transfer drum, and the transfer drum is provided with a gripper. An elastic member made of sponge or rubber is provided on the lower surface of the claw on the abutting surface of the gripper.

[0016]

The image forming apparatus of the present invention will be described in more detail with reference to the drawings. In the embodiments described below, the image forming apparatus is an electrophotographic color laser beam printer, but the present invention is not limited to this.

Embodiment 1 FIG. 1 shows an electrophotographic color laser beam printer according to an embodiment of the present invention.

[Overall Description of Image Forming Apparatus] First, the overall configuration of a laser beam printer will be outlined with reference to FIG.

In the present embodiment, the laser beam printer has an image bearing member 4a which is a drum-shaped electrophotographic photosensitive member. Around the photosensitive drum 4a, a charging means 4b and an exposure device. 10, a developing device 5, a transfer device 3, and a cleaning means 4c are arranged. In this embodiment,
The photosensitive drum 4a, the charging unit 4b, and the cleaning unit 4c form the image carrier unit 4. Further, in FIG. 1, a fixing unit 6 is arranged obliquely above the transfer device 3, and a feeding unit 1 is arranged below the transfer device 3.

The recording material fed from the feeding portion 1, that is, the transfer material 2 is wound around the transfer drum 3A of the transfer device 3 and conveyed, and four developing devices 5M, 5C, 5Y, 5 which are rotatably movable.
A color image is formed on the transfer material 2 by multiple-transferring the toner images developed by the developing device 5 loaded with Bk onto the transfer material 2. The transfer material 2 is separated by the separating means 40.
Then, the color image is separated from the transfer drum 3A and conveyed to the fixing unit 6, where the color image is fixed on the transfer material 2, and is discharged to the discharging unit 8 at the upper part of the apparatus by the discharging roller pair 7.

Next, the configuration of each part of the image forming apparatus will be sequentially described in detail.

[Image-bearing member (photosensitive drum)] In this embodiment, the image-bearing member is the electrophotographic photosensitive drum 4a as described above, and the organic photoconductive material is formed on the outer peripheral surface of the aluminum cylinder having a diameter of about 40 mm. The body layer is formed by coating, and its rotation shaft 4e is rotatably supported by the image carrier unit 4. The photoconductor drum 4a transmits the driving force of a drive motor (not shown) to one end of the rotary shaft 4e, thereby causing the photoconductor drum 4a to move in the arrow direction (counterclockwise direction) of FIG. 1 according to the image forming operation. Rotate to. This image carrier unit 4
Is detachable from the apparatus main body 9, and the photosensitive drum 4
It can be easily replaced according to the life of a.

[Charging Means] The charging means 4b is disclosed in JP-A-63
It is a so-called contact charging device as disclosed in Japanese Patent Publication No. 149669, in which a conductive roller is brought into contact with the photosensitive drum 4a,
By applying a voltage to this conductive roller, the surface of the photosensitive drum 4a is uniformly charged.

[Exposure Device] The exposure device 10 includes a scanner unit, and exposes the photosensitive drum 4a. That is,
When the image signal is given to the laser diode, the laser diode irradiates the polygon mirror 10a with image light corresponding to the image signal. This polygon mirror 10a
Is rotated at a high speed by a scanner motor, and the image light reflected by the polygon mirror 10a is irradiated from the exposure section of the photoconductor drum unit 4 via the imaging lens 10b and the reflection mirror 10c to selectively expose the photoconductor drum 4a. .
As a result, a latent image is formed on the photosensitive drum 4a.

[Developing Device] The developing device 5 develops the latent image into a toner image, that is, a visible image, and four developing devices capable of developing magenta, cyan, yellow, and black colors. It has vessels 5M, 5C, 5Y and 5Bk. These four developing units 5M, 5C, 5Y and 5Bk have the same structure and are rotatably arranged around the shaft 5e.
Although not shown, the center of each developing device is configured to rotate in association with a rotation gear arranged on the outer periphery of the revolving gear, so that the posture of the developing device is always kept constant.

At the time of image formation, developing devices 5M and 5M corresponding to each color development of magenta, cyan, yellow and black.
C, 5Y, and 5Bk rotate around the shaft 5e, and the predetermined developing device stops at the position facing the photoconductor drum 4a.
In FIG. 1, the magenta developing device 5M is in the developing position. In this state, the developing sleeve 5b of each developing unit is positioned so as to face the photoconductor drum 4a with a minute gap (about 300 μm), and a visible image is formed on the photoconductor drum 4a by toner.

In each developing device, the toner in the container corresponding to the color to be developed is fed to the coating roller 5a by the feeding mechanism, and a thin layer of toner is coated on the outer periphery of the sleeve 5b rotated by the rotary coating roller 5a and the blade 5c. In addition, the toner is charged (triboelectrically charged). By applying a developing bias between the sleeve 5b and the photoconductor drum 4a on which the latent image is formed, toner development is performed on the photoconductor drum 4a according to the latent image.

Further, the sleeve 5b of each developing unit 5 is connected to a high-voltage power source for developing each color provided in the apparatus main body 9 when each developing unit is rotationally moved to the developing position, and it is selective for each developing of each color. A voltage is applied to.

The rotatable developing device is detachably attached to the apparatus main body 9.

[Feeding Unit] The feeding unit 1 feeds the transfer material 2 to the transfer device 3, and a paper feed cassette 1 a containing a plurality of transfer materials 2 is provided on the inner bottom of the apparatus main body 9. To load. During image formation, the feeding roller 1b is driven and rotated according to the image forming operation to separate and feed the transfer materials 2 in the cassette 1a one by one, and are guided by the guide plates 1c and 1d to be transferred through the registration rollers 1e. Feed to drum 3A.

The feeding of the transfer material 2 to the transfer drum 3A is stopped after the leading edge is detected by an optical leading edge detection sensor 16 disposed downstream of the registration roller after passing through the registration roller 1e, and the transfer drum 3A is stopped. When the predetermined position of is detected, the sheet is fed again, guided by the guide member 15 and transferred to the transfer drum 3A.

[Transfer Device] The transfer device 3 is provided with a drum-shaped transfer drum 3A in the present embodiment, the transfer material 2 fed from the feeding portion 1 is wound around, and a toner image of each color is formed on the photosensitive drum 4a. In order to transfer to the transfer material 2, it rotates in the arrow direction of FIG. The transfer drum 3A has cylindrical flanges 31 arranged on both sides, as will be understood with reference to FIG.
And a drum cylinder 32 disposed between both flanges 31.

In the present embodiment, the drum cylinder 32 comprises an aluminum cylinder 3a having a diameter of about 160 mm, an elastic layer 3b such as sponge or rubber formed on the outer circumference of the aluminum cylinder 3a, and a resistance layer 3c on the outer circumference thereof. It is composed of the dielectric layer 3d provided on the outermost periphery.

The transfer drum 3A is rotatably supported by a fixed shaft 3e, and the driving force of a drive motor (not shown) is transmitted to a gear 33 (FIG. 2) fixed to the transfer drum 3A to form an image. In accordance with the operation, it rotates in the arrow direction (clockwise direction) in FIG.

At a predetermined position on the outer circumference of the transfer drum 3A,
As can be seen from FIG. 2, in this embodiment, grippers 3f are provided at two locations to grip the leading end of the fed transfer material 2. The place where the gripper 3f is installed is not limited to two places as shown in FIG. 2, and may be arbitrary as required.

The gripper 3f is located radially inward of the circumferential surface of the flange 36 of the transfer drum 3A with which the photosensitive drum 4a abuts in order to avoid contact with the photosensitive drum 4a. When the transfer material 2 is separated, the gripper 3f is opened and the tip of the transfer material is lifted by the push-up portion of the gripper 3f, and is guided to the tip of the separation claw of the separation means 40 and separated.

Further, the transfer device 3 has an electrostatic attraction roller 3g which is provided on the outer circumference of the transfer drum 3A so as to be able to come into contact with and separate from it. The transfer material 2 is pressed against the outer circumference of the transfer drum 3A by the electrostatic suction roller 3g so as to be sandwiched between the electrostatic suction roller 3g and the transfer drum 3A, and between the electrostatic suction roller 3g and the transfer drum 3A. By applying a voltage to the transfer material 2 which is a dielectric and the dielectric layer 3d of the transfer drum 3A, an electric charge is induced, and the transfer material 2 is transferred to the transfer drum 3A.
Electrostatically adsorbed on the outer circumference of A.

The method of attracting the transfer material 2 to the transfer drum 3A is not limited to the electrostatic attraction, but may be a suction method using air or the like.

The surface of the transfer drum 3A is cleaned by the transfer drum cleaning means 20 as needed.

[Cleaning Means] In this embodiment, the cleaning means comprises a cleaning blade 4c mounted on the image carrier unit 4 and removes the untransferred residual toner remaining on the photosensitive drum 4a. Clean with a blade.

In the cleaning means 4c of this embodiment, the toner removed from the photosensitive drum 4a is sent to the waste toner container (not shown) attached to the side surface of the main body by the waste toner carrying screw 4d, and the waste toner container When the waste toner of is full, it is removed and replaced.

[Fixing Section] The transfer material 2 on which the multicolor image has been transferred and separated from the transfer drum 3A by the separating means 40 is fed to the fixing section 6, and the toner image on the transfer material 2 is transferred. It is fixed on the material 2. The fixing unit 6, as shown in FIG.
It is composed of a driving roller 6a that is driven and rotated, and a fixing roller 6b that presses against the driving roller 6a and applies heat and pressure to the transfer material 2.
That is, the transfer material 2 separated from the transfer drum 3A is fixed to the fixing unit 6
While being conveyed by the drive roller 6a, heat and pressure are applied by the fixing roller 6b. As a result, the image forming toner is fixed on the transfer material 2.

The cleaning member 6c is in contact with the fixing roller 6b, and the toner attached to the fixing roller 6b is removed by the cleaning member 6c.

[Image Forming Operation] Next, an image forming operation of the image forming apparatus having the above-described configuration will be described.

The feeding roller 1b shown in FIG. 1 is rotated to separate one transfer material 2 in the paper feeding cassette 1a, and the transfer drum 3
Deliver to A. The transfer drum 3A rotates in the direction of the arrow in FIG. 1 and holds the front end of the transfer material 2 fed by the gripper 3f at a timely timing, and electrostatically adsorbs it on its peripheral surface.

In synchronization with the rotation of the transfer drum 3A, the photosensitive drum 4a is rotated in the direction of the arrow in FIG. 1, and the photosensitive drum 4a is uniformly charged on the drum surface by the charging means 4b. A magenta image is irradiated by 10 to form a magenta latent image on the photosensitive drum 4a. At the same time as this latent image formation, the magenta developing device 5
M is driven, and magenta development is performed by applying a voltage of substantially the same potential as the charging polarity of the photosensitive drum 4a so that magenta toner adheres to the latent image on the photosensitive drum 4a. By applying a voltage having a polarity opposite to that of the toner, the toner on the photosensitive drum 4a is transferred to the transfer material 2 on the transfer drum 3A.

When the transfer of the magenta toner is completed as described above, the next developing device is rotationally moved and positioned at a position facing the photosensitive drum, and latent images of cyan, yellow and black are formed in the same manner as magenta. And toner transfer are sequentially performed to form a color image on the transfer material 2.

When the image formation is completed, the transfer material 2 is neutralized by the static eliminator 3h, then separated from the transfer drum 3A by the separating means 40, conveyed to the fixing section 6, and fixed by the fixing section 6. After that, the sheet is discharged onto the discharge tray 8 by the pair of discharge rollers 7.

Next, the gripper 3f of the transfer device 3 constructed according to the present invention will be described with reference to FIG.

The entire structure of the gripper 3f is similar to the conventional one. The gripper 3f has a gripper main body 33 having a substantially rectangular cross section, and both ends of a side surface 36a along the longitudinal direction of the gripper main body 33, A C-shaped mounting portion 34 is formed. The gripper 3f is attached to the pivot shaft 35 provided on the transfer drum 3A via the attachment portion 34.

The pivot shaft 35 is integrally attached to the actuating lever 35 extending inward in the radial direction of the transfer drum 3A as shown in FIG.
Drive means 50 such as a drive cam or electromagnetic solenoid
Thus, when the actuating lever 35 is swung in the arrow direction, the pivot shaft 35 is also swung in the same direction. As a result, the gripper 3f swings between the closed position for holding the transfer material 2 (the position indicated by the alternate long and short dash line in FIG. 4) and the open position for receiving or releasing the transfer material (the position indicated by the solid line in FIG. 4). To do. This structure is also similar to the conventional one.

On the other side surface 36b side of the gripper main body 33, on both upper surfaces of both ends thereof, the transfer material 2 cooperates with the transfer material carrying surface of the transfer drum 3A when the gripper 3f is closed.
An upper claw 37 that presses the upper end of the
When the gripper 3f is opened, the lower claw 38 for contacting with the lower end of the tip of the transfer material 2 and pushing the transfer material 2 outward from the surface of the transfer drum is formed.

According to the present invention, the side surface 36b has the upper claw 37.
The lower part is formed to be more convex than the other parts. Therefore,
The tip of the transfer material 2 will abut this convex side surface 36c of the side surface 36b. Since the other portion of the side surface 36b is a concave portion than the convex side surface 36c, the tip of the transfer material 2 does not abut.

According to the present invention, by arranging the gripper 3f as described above, it will be understood as compared with the conventional gripper of FIG. 3 (the structure shown by the phantom line in FIG. 5).
The area in which the transfer material 2 abuts on the gripper 3f can be reduced, and therefore, the shock when the transfer material enters the gripper 3f can be alleviated. for that reason,
In the present invention, the problem that the toner image transferred to the transfer material 2b at the transfer position T is disturbed due to the rush shock when the transfer material 2 rushes into the gripper 3f as described in FIG. 3 is prevented. At the same time, it is possible to prevent edge of the transfer material 2 from being soiled.

Further, according to the present invention, since the contact area of the gripper 3f with the transfer material 2 is made small, the gripper 3f is caused by the toner scattering in the image forming apparatus or the toner scattering at the time of cleaning the transfer drum. Can be minimized, and therefore, toner adhesion to the tip of the transfer material can be prevented.

Embodiment 2 FIG. 6 shows a second embodiment of the present invention. In Example 1,
On the side surface 36b side of the gripper body 33, except for the lower portion of the upper claw 37, the lower portion of the upper claw 37 is formed in a convex shape by forming the other portion to be a concave portion. In the second embodiment, the upper claw 3 of the abutting surface 36b of the gripper 3f.
Elastic member 39 made of sponge or rubber on the lower part of 7.
By providing the above, the lower portion of the upper claw 37 is formed in a convex shape.

Therefore, also in this embodiment, the abutting surface against which the tip of the transfer material abuts is formed by the convex side surface of the elastic member 39 provided on the side surface 36b, and the other side surface 36b portion is formed by this elastic member. Since the concave side is formed from the convex side surface, the tip of the transfer material 2 does not hit.

Further, according to this embodiment, since the convex portion on which the transfer material abuts is an elastic member, the rush shock when the transfer material 2 rushes into the gripper 3f is alleviated, and the transfer material 2 is gripped. It is possible to effectively prevent the problem that the toner image transferred to the transfer material 2b is disturbed at the transfer position T due to the rush shock when entering the 3f, and at the same time, to prevent the edge of the transfer material 2 from being soiled. it can.

Third Embodiment FIG. 7 shows a third embodiment of the present invention. Generally, the protrusion amount of the transfer material 2 fed from the feeding unit 1 into the gripper 3f is set to about 1.5 to 2.0 mm as shown in FIG. 6, but in the present embodiment, it is previously set. , The transfer timing of the transfer material 2 at the registration roller 1e is adjusted, and the gripper 3f is adjusted.
The amount of rush into is set to 0 to 1.5 mm.

With such a structure, the loop of the transfer material 2 formed when the transfer material 2 plunges into the gripper 3f can be made small, whereby the force of the transfer material 2 pressing the transfer drum 3A becomes small, and the gripper 3f becomes small. The inrush shock is alleviated, the adverse effect on the latent image formation and the transfer material 2
It is possible to prevent the image from being disturbed.

Further, more preferably, as shown in FIGS. 6 and 7, the loop of the transfer material 2 when the gripper is inserted is formed so as to be on the lower side. With this configuration, the force of the transfer material 2 pressing the transfer drum 3A is reduced, the gripper rush shock is alleviated, and it is possible to prevent an adverse effect on latent image formation and an image disturbance of the transfer material 2.

[0062]

As described above, in the transfer device and the image forming apparatus according to the present invention, the transfer device is provided with the gripper having the claw for pressing and holding the tip of the transfer material from the upper part thereof. As for the abutting surface on which the tip of the transfer material fed to the transfer device abuts, the lower part of the claw is formed to be more convex than the other part, or the abutting surface of the gripper has a convex cushioning material. According to another method, the amount of transfer material rushing into the gripper is reduced, and more preferably, the transfer material loop is formed on the lower side when the gripper rushes, so that a latent image is formed. In addition, it is possible to obtain a higher quality image by eliminating the mechanical influence on the transferred image. Further, according to the present invention, by improving the shape of the gripper, it is possible to prevent the tip portion of the transfer material from being soiled.

[Brief description of drawings]

FIG. 1 is a schematic configuration sectional view showing an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a plan view of the transfer device of the present invention, showing the relationship between the gripper and the transfer drum.

FIG. 3 is a perspective view of a conventional gripper.

FIG. 4 is an explanatory diagram showing a relationship between a transfer drum and a transfer material fed.

FIG. 5 is a perspective view of one embodiment of a gripper according to the present invention.

FIG. 6 is a perspective view of another embodiment of the gripper according to the present invention.

FIG. 7 is an explanatory diagram showing a relationship between a transfer drum and a transfer material fed.

FIG. 8 is an explanatory diagram showing a relationship between a transfer drum and a transfer material fed.

[Explanation of symbols]

 1 Feeding Part 2 Transfer Material 3 Transfer Device 3A Transfer Drum 3f Gripper 33 Gripper Body 34 Attachment Part 36c Convex Part 37 Upper Claw 38 Lower Claw 39 Elastic Member 4a Image Carrier (Photoreceptor Drum) 5 Developing Device

Claims (10)

[Claims] 1. A transfer material in which a latent image is formed on an image carrier, the latent image is developed to form a visible image, and the visible image is carried on a transfer material carrying surface of a transfer device and conveyed. In the image forming apparatus for transferring the image onto the transfer device, the transfer device has a gripper having a claw for holding and holding the tip of the transfer material from above, and the gripper is fed to the transfer device. The image forming apparatus is characterized in that an abutting surface against which the leading end of the supplied transfer material abuts is formed such that a lower side portion of the claw is more convex than other portions. 2. The image forming apparatus is a color image forming apparatus, which forms a latent image according to each color component on an image carrier,
A latent image is developed with a developer corresponding to each color component to form a visible image, and the visible image is superimposed and transferred onto a transfer material carried by a transfer device and conveyed to obtain a multicolor image. The image forming apparatus according to item 1. 3. The image forming apparatus according to claim 1, wherein the transfer device includes a transfer drum that provides a transfer material carrying surface, and the gripper is provided on the transfer drum. 4. The image forming apparatus according to claim 1, 2 or 3, wherein an elastic member made of sponge or rubber is provided on a lower portion of the claw on an abutting surface of the gripper to form a convex shape. 5. The pressing amount when the front end of the transfer material fed to the transfer device is abutted against the abutting surface of the gripper is 0 to 1.5 mm.
Image forming apparatus. 6. The loop of the transfer material when the front end of the transfer material fed to the transfer device abuts on the abutting surface of the gripper, the loop of the transfer material is formed on the lower side. 2, 3, 4 or 5 image forming apparatus. 7. A transfer material in which a latent image is formed on an image carrier, the latent image is developed to form a visible image, and the visible image is carried on a transfer material carrying surface of a transfer device and conveyed. In the image forming apparatus for transferring the image onto the transfer device, the transfer device has a gripper for gripping the tip of the transfer material, and the tip of the transfer material fed to the transfer device is protruded by the gripper. An image forming apparatus characterized in that the amount of pushing when hitting the contact surface is 0 to 1.5 mm. 8. A transfer device, which carries and conveys a transfer material for transferring a visible image formed on an image bearing member onto the transfer material, for pressing and grasping the tip of the transfer material from above. Having a gripper with claws, of this gripper,
The transfer device is characterized in that an abutting surface against which a tip of a transfer material fed to the transfer device abuts is formed such that a lower part of the claw is formed in a convex shape as compared with other parts. 9. The transfer device according to claim 8, wherein the transfer device includes a transfer drum that provides a transfer material carrying surface, and a gripper is provided on the transfer drum. 10. The transfer device according to claim 8, wherein an elastic member made of sponge or rubber is provided on a lower side portion of the claw on an abutting surface of the gripper to form a convex shape.