JPH0610374Y2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a belt shape in which a toner image obtained by developing a latent image formed by exposing on a photoconductor is transferred in contact with the photoconductor. The present invention relates to an image forming apparatus configured to transfer onto a transfer paper held by a transfer body.

(Prior Art) A color copying machine as an image forming apparatus will be described. A scanning optical system for scanning a document sequentially exposes a multi-color separated light image of a color document onto a drum-shaped photosensitive member to form a latent image for each color separation. Formed respectively. Then, each of the latent images is developed with complementary complementary color toners, and the toner images of each color are repeatedly transferred onto the transfer paper held on the transfer body.

In recent years, a belt-shaped transfer member is often used as the transfer member. This belt-shaped transfer member is one that is driven to reciprocate while holding a transfer paper, and holds the transfer paper fed from a transfer paper cassette by a paper feed roller and a registration roller and provides it for a plurality of times of transfer. It is a thing. Such a belt-shaped transfer member is arranged such that its transfer portion is close to the above-mentioned photosensitive member, and a transfer charger for transferring a toner image is arranged in the transfer portion. Further, a separation claw for peeling off the transfer paper on the belt-shaped transfer body is provided at a position slightly distant from the transfer section so as to swing. The separating claw is swung so that the tip end of the separating claw is brought into contact with the belt-shaped transfer body when separating the transfer portion sent from the transfer section while being held on the belt-shaped transfer body. Then, the transfer paper is peeled off by the front end of the transfer paper contacting the separation claw.

However, since the transfer paper after the transfer is attached to the belt-shaped transfer body with a relatively strong force by electrostatic attraction, the tip of the separation claw can perform a good peeling operation. However, there is often a problem that a jamming phenomenon of the transfer paper, a toner scattering phenomenon at the time of separation, and the like occur only by the action of the separating claw. In addition, when the transfer paper is peeled off, peeling discharge may occur to disturb the toner image, and at the time of separation, the transfer paper may be buckled to cause transfer blurring.

(Purpose) Therefore, an object of the present invention is to provide an image forming apparatus capable of favorably separating the transfer paper on the belt-shaped transfer body.

(Structure) In order to achieve the above object, the present invention provides a color copy by transferring a plurality of toner images of different colors sequentially formed on a photoconductor onto a transfer paper in the same number of times as the number of toner image colors. In the image forming apparatus for carrying out the above, a transfer belt that reciprocates while supporting the transfer paper, and a range of the transfer belt that reciprocates while supporting the transfer paper is at least twice as long as the transfer paper. A transfer belt having a transfer unit in contact with the photoconductor is located substantially at the center of the reciprocating range of the transfer belt, and is arranged above the transfer belt on the downstream side of the transfer unit to transfer the toner image on the transfer paper. A fixing device for fixing, a separation claw arranged between the transfer part and the fixing device and guiding the transfer paper on the transfer belt to the fixing device, and arranged between the separation claw and the transfer part. The above transfer belt and transfer paper Between the static eliminator for removing the static electricity, and the static eliminator and the separation claw, and is arranged inside the transfer belt near the tip of the separation claw, and the transfer belt is projected to the transfer paper holding side. And a transfer sheet deflecting member which is curved with a predetermined curvature so that

In the apparatus having such a configuration, the belt-shaped transfer body and the transfer paper sent from the transfer section while being held on the belt-shaped transfer body are first subjected to static elimination by the static eliminator, and then the belt-shaped transfer body. The body is curved with a predetermined curvature by the transfer paper deflecting member so as to be convex toward the transfer paper holding side, whereby the transfer paper is slightly lifted from the belt-shaped transfer body to create a separation start. In such a state, the front end portion of the transfer paper is reliably engaged with the front end portion of the separation claw, and the transfer paper is peeled off favorably from the transfer belt side.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows the overall construction of a color copying machine to which the present invention is applied. A photoconductor belt 1 that is transported in the direction of arrow A is provided at the center of the copying machine body. OPC, Se-based, ZnO-based, etc. are used as the photosensitive belt 1, but not limited to the belt-shaped photosensitive body as in the present embodiment, a drum-shaped one can also be adopted. Also,
A charging charger 2 and an eraser 3 are provided around the photoconductor belt 1, and a scanning optical system 4 is provided in the next stage. This scanning optical system 4
Is a well-known one, which is composed of a lamp, a plurality of mirrors, an imaging lens, etc., and repeats the operation of scanning from the home position to a length corresponding to the length of the document and returning to the home position again. is there. Then, in the optical path of the scanning optical system 4,
A color separation filter 5 is provided. Further, the developing device 6 is provided at a stage subsequent to the image forming position of the scanning optical system 4. The developing device 6 includes a black developing device 6B for black and white copying, a magenta developing device 6M, a cyan developing device 6C, and a yellow developing device 6Y for color copying. As each developing device, either one-component type or two-component type can be adopted.

Further, a pre-transfer static eliminator 7 is arranged at the subsequent stage of such a developing device 6, and immediately after that, a transfer belt 9 formed of an endless belt that holds the transfer paper 8 and drives it to reciprocate. It is provided. The transfer belt 9 holds the transfer paper 8 fed from the transfer paper cassette 10 by the paper feed roller 11 and the registration roller 12 and uses the transfer paper 8 for multiple times of transfer. A dielectric material (polyester film, vinylidene fluoride, nylon, etc.) is used as the belt material.

Such a transfer belt 9 is arranged such that its transfer portion is close to the photoreceptor belt 1, and
A transfer charger 13 for transferring the toner image is arranged. Further, the transfer belt 9 is swingably installed by a solenoid (not shown) or the like so as to be separated from the transfer portion as shown by a chain line. Further, as shown in FIG. 1 in particular, a static eliminator 14 for discharging the transfer paper 8 and the transfer belt 9 is located slightly away from the transfer section on the downstream side of the transfer section in the transfer sheet conveying direction (left direction in the drawing). And a fixed roller 15 as a transfer sheet deflecting member is provided immediately after the static eliminator 14 on the downstream side.
Are arranged so as to contact the inner surface side of the transfer belt 9. This fixed roller 15 is provided when the transfer belt 9 is pushed slightly downward by a separating claw 16 which will be described later.
The transfer belt 9 is curved with a predetermined curvature so as to be convex toward the holding side of the transfer paper 8. The separation claw 16 is
It is provided so as to be swingable further rearward of the fixed roller 15. The separation claw 16 is driven by a solenoid (not shown) or the like, and can be swung between a non-actuated position indicated by a two-dot chain line and a separation actuated position indicated by a solid line. ing. The swinging tip of the separation claw 16 at the separation operation position is pressed against the upper surface of the transfer belt 9, and the transfer belt 9 is pushed downward by a predetermined amount by the pressure contact force of the separation claw 16. In this state, the front end portion of the transfer paper 8 is engaged with the separation claw 9 and the transfer paper 8 is peeled off from the transfer belt 9 side.

Immediately after the separation claw 16, a guide plate 17 that guides the separated transfer paper is arranged close to it. The guide plate 17 extends to the fixing device 18. Reference numeral 19 indicates a transfer belt cleaning device that scrapes off the residual toner on the transfer belt 9, and reference numeral 20 indicates a cleaning device that scrapes off the residual toner on the photosensitive belt 1.

Next, the control system of such a copying machine will be described with reference to FIG.

For the photoconductor belt 1, the scanning optical system 4, and the transfer belt 9, a servo motor 2 as a drive source is provided.
1, 22, and 23 are provided independently of each other. The servo motor 22 is under the control of the motor control board 24, and the servo motors 21 and 23 are under the control of the motor control board 25. Further, the scanning optical system 4 is provided with a scanning home sensor for detecting a scanning start time, that is, a home position position.
The detection signal from the scanning home sensor is input to the main control board 26. Further, a position marker indicating the home position of the transfer belt 9 is attached, and this position marker is detected by the transfer belt home sensor, and the detection signal is also input to the main control board 26. A scanner running start signal, a photosensitive belt speed command signal, a transfer belt reference signal, and the like are communicated between the main control board 26 and the motor control board 24, and the motor control board 24 and the motor control board 25 are also communicated. A transfer belt position command signal, a transfer belt speed command signal, a photoconductor belt speed command signal, a clock pulse signal, and the like are communicated between and.

Furthermore, on the main control board 26,
An operation / display control board 27 is connected,
Between the operation / display control board 27 and the main control board 26, a transfer paper size signal, a copy number signal, a scaling signal, and a color / monochromatic copy mode signal are communicated.

In the apparatus in such an embodiment, the optical image of the original is exposed on the photosensitive belt 1 which is transported at a constant speed by scanning the original by the scanning optical system 4, and the image is formed on the photosensitive belt 1. The formed latent image is developed into a toner image in the developing device 6, and the toner image is transferred to the transfer paper 8 which is held and transferred by the transfer belt 9 to obtain a copy. The transfer paper 9 is sent from the transfer paper cassette 10 by the paper feed roller 11 and the registration roller 12 and placed on the transfer belt 9, and is transferred by the electric field generated from the transfer charger 13 at the transfer portion. The transfer belt 9 and the photoconductor belt 1 are transported in the same direction at the same speed.

The separation claw 16 is swung downward at the time of transfer or immediately after the transfer and is pressed against the transfer belt 9. This allows
The transfer belt 9 is pushed down by a predetermined amount, and the installation portion of the fixed roller 15 is curved upward in a convex shape. As a result, the transfer paper 8 is slightly floated from the transfer belt 9 side,
The stake for separating the transfer paper will be created. In this state, when the transfer paper 8 is conveyed and reaches the separation claw 16,
The front end portion of the separation claw 16 is securely engaged with the front end portion,
The transfer paper 8 is peeled off well from the transfer belt 9 side.

The transfer paper 8 after separation passes through the guide plate 17 and the fixing device 18
To be heated and fixed there, and then discharged outside the machine. In this case, during color copying, scanning is repeatedly performed to sequentially expose the color original on the photosensitive belt 1 in a plurality of colors, and each latent image is developed with complementary color toners and repeatedly transferred to the transfer paper 8. Becomes

When the transfer of the first color of the transfer belt 9 is completed, the transfer belt 9 is swung up to the position indicated by the one-dot chain line by a solenoid (not shown) and separated from the transfer section, and then transferred in the opposite direction and transferred. The paper 8 is returned to a position where its leading end does not come into contact with the transfer portion and stopped. Then, after the transfer belt 9 is returned to the position in contact with the transfer portion again, the transfer of the second color is performed. When such reverse conveyance and transfer of the second color are performed, since the transfer paper 8 has already been transferred for the first time, it is electrostatically adsorbed to the transfer belt 9 side and is displaced with respect to the transfer belt 9. It is conveyed integrally without causing. When a large-sized transfer sheet is used, it can be temporarily received by a transfer sheet receiving stand provided so as to extend from the front end portion (the left end portion in the drawing) of the transfer belt 9. By repeating such steps, color combination is performed and a final color image is obtained.

In such a copying operation, the transfer belt 9, the photoconductor belt 1 and the scanning optical system 4 are subjected to independent servo motor drive control.
Good synchronization is achieved, and positional deviations of the three parties are completely prevented. Further, the reverse conveyance speed (return speed) of the transfer belt 9 may be changed according to the size of the transfer paper 8, the moving amount (distance) of the transfer belt 9 may be changed, and the scanning optical system 4 may be short-returned. The copying operation can be efficiently executed by arbitrarily performing the above.

In the embodiment shown in FIG. 4 in which the same components as those of the embodiment shown in FIG. 1 are represented by the same reference numerals, the transfer sheet deflecting member is a rocking roller arranged so as to be in contact with the inner surface side of the transfer belt. It is formed from 31. This rocking roller 31
Is rotatably attached to one end of the lever 32, and is vertically moved by swinging the other end of the lever 32. Then, when the transfer paper 8 is separated, the swing roller 31 is lifted upward as shown in the drawing, and the transfer belt 9 is curved upward in a convex shape. As a result, the transfer paper 8 becomes the transfer belt 9
It will be slightly floated from the side, and it will be a starting point for separating the transfer paper. In this state, when the transfer paper 8 is conveyed and reaches the separation claw 16, the front end portion of the separation claw 16 is securely engaged with the transfer paper 8 and the transfer paper 8 is satisfactorily peeled from the transfer belt 9 side. It will be taken.

(Effects) As described above, according to the present invention, the transfer paper separating portion of the belt-shaped transfer body is provided with a static eliminator for removing electric charges, a transfer paper deflecting member for making a start for separating transfer paper, and a separation for separating transfer paper. Since the transfer paper is peeled off by arranging the claws in order, the transfer paper is peeled off smoothly and smoothly, and the image damage due to the occurrence of separation jam and toner scattering during separation is completely prevented. be able to. In addition, since a good separation operation can be performed, it is possible to reliably avoid the occurrence of transfer deviation or blurring at the transfer portion. Furthermore, the transfer paper deflecting member is disposed inside the transfer belt, Since the transfer sheet is curved so as to be convex on the transfer sheet holding side, the transfer sheet deflecting member does not touch the transfer sheet, and therefore the unfixed toner image on the transfer sheet is not disturbed, so that the image quality can be improved. it can.

[Brief description of drawings]

FIG. 1 is a partially enlarged schematic explanatory view showing a transfer paper separating portion in one embodiment of the present invention, and FIG. 2 is a schematic configuration explanatory view showing an entire copying machine in one embodiment of the present invention.
FIG. 4 is a block diagram of the operation control system, and FIG. 4 is a partially enlarged schematic explanatory view showing a transfer paper separating portion in another embodiment of the present invention. 1 ... Photosensitive belt, 9 ... Transfer belt, 13 ... Transfer charger, 14 ... Separation charger, 15 ... Fixed roller, 16 ... Separation claw, 31 ... Oscillating roller.

Claims (3)

[Scope of utility model registration request] 1. An image forming apparatus for performing color copying by transferring a plurality of toner images of different colors sequentially formed on a photoconductor onto a transfer paper by the same number of times as the number of toner image colors. A transfer belt that supports and reciprocates the transfer belt,
A transfer belt having a length at least twice that of the transfer paper and in which the transfer portion in contact with the photoconductor is located substantially in the center of the reciprocating range of the transfer belt; and the transfer belt on the downstream side of the transfer portion. A fixing device disposed above and fixing the toner image on the transfer paper; a separation claw disposed between the transfer unit and the fixing device and guiding the transfer paper on the transfer belt to the fixing device; A static eliminator disposed between the separation claw and the transfer portion to remove static electricity from the transfer belt and the transfer paper; and between the static eliminator and the separation claw, near the tip of the separation claw. An image forming apparatus comprising: a transfer sheet deflecting member that is disposed inside the transfer belt and that bends the transfer belt with a predetermined curvature so as to be convex toward the transfer sheet holding side. 2. The utility model registration claim wherein the transfer sheet deflecting member is a roller rotatable at a fixed position, and the separating claw is swingable so as to press the outer surface of the transfer belt. The image forming apparatus according to item 1 above. 3. The image forming apparatus according to claim 1, wherein the transfer sheet deflecting member is a roller that can swing in a direction of pressing the inner surface of the transfer belt.