JPH0570821B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a transfer device for transferring toner images formed on a plurality of photosensitive drums of a color copying machine onto a sheet of paper in superimposed colors.

2. Description of the Related Art In general, as a means of obtaining a color image by electrophotography, an electrostatic latent image formed on a single photosensitive drum is developed three times using toners of three colors, for example, yellow, magenta, and cyan. A method of obtaining a transferred image by overlapping the colors three times by transferring these developed images onto paper;
There is a method of forming yellow, magenta, and cyan developed images on a plurality of, for example, three photosensitive drums, and transferring these developed images onto paper three times at different transfer points to obtain a transferred image. 1977-
122067, 49-84446).

Regarding a transfer device that independently forms and transfers toner images onto three photosensitive drums, the applicant has proposed, for example, a device as shown in FIGS. 3 to 6. When the transfer paper 3 is conveyed from the paper feed cassette 1 onto the conveyor belt 4 by the conveyor roll 2, a paper feed sensor (not shown) moves the transfer paper 3 onto the conveyor belt 4.
The rotation timing of the photosensitive drums 5 to 7 is determined based on this detected paper feeding signal. The electrostatic latent images formed on the photosensitive drums 5 to 7 are made visible by a developing device (not shown) that supplies cyan, magenta, and yellow toners, and this visible image travels on the conveyor belt 4 as shown in FIG. The image is transferred onto a transfer sheet transported in the direction of arrow A at a predetermined timing. On the surface of the conveyor belt 4 opposite to the photosensitive drums 5 to 7, suction brushes 10 to 12 for sucking paper onto the conveyor belt 4 are provided corresponding to the photosensitive drums 5 to 7, respectively.
Transfer brushes 13 to 1 which transfer the toner images on the photosensitive drums 5 to 7 onto paper onto the downstream side of the photosensitive drums 5 to 12, respectively.
5 is installed. On the downstream side of each transfer point of the photosensitive drums 5 to 7, there is a peeling claw 16 that peels off the transfer paper from the drum surface so that the transfer paper onto which a predetermined color toner image has been transferred does not wrap around the respective photosensitive drums 5 to 7. ~18 are provided.

As shown in FIGS. 3 and 4, the conveyor belt 4 is
It is constructed by adhering a support 21 to the back side of a semiconductive resin film 20 with a thickness of 0.5 mm and a volume resistivity of 10 ^{to 10} Ω·cm, and the support 21 is provided with a predetermined interval in the belt conveyance direction. The electrodes 25 and 26 are arranged alternately. The ends of the electrodes 25 and 26 are connected to the support 21
Terminals 25a and 26a are exposed on both sides on the back surface of the , and suction brushes 10 to 1 are attached to these terminals 25a and 26a from the bottom surface as the conveyor belt 4 moves.
2 or transfer brushes 13 to 15 are in contact with each other.

When the electrodes 25 and 26 contact the suction brushes 10 to 12, for example, the grounded brush contacts the terminal 25a of the electrode 25, and the terminal 26a of the other electrode 26 is connected to the terminal 26a of the other electrode 26 via the DC power supply 27 and the switch 28. A positive voltage is applied,
As a result, the electrostatic attraction generated between the electrodes 25 and 26 causes the paper to be attracted onto the surface of the semiconductive resin film 20. When the electrodes 25 and 26 contact the transfer brushes 13 to 15, the DC power source 29
A positive voltage is applied to both the electrodes 25 and 26 via the switch 30, so that the negatively charged toner images on the photosensitive drums 5 to 7 are transferred to the transfer paper on the semiconductive resin film 20. It's getting old.

In this way, the paper is attracted onto the conveyor belt 4 by the suction brush 10, and the cyan toner image is transferred onto the photosensitive drum 5 at the transfer point by the transfer brush 13, and then onto the conveyor belt by the suction belt 11. The transfer paper is transferred while being adsorbed, and the transfer brush 14 transfers the magenta toner image on the photosensitive drum 6 in a superimposed color.The transfer paper is then transferred to the conveyor belt 4 while being adsorbed by the suction brush 12. The yellow toner image on the photosensitive drum 7 is transferred onto the transfer paper by the transfer brush 15 in superimposed colors, thereby forming a desired color image on the transfer paper, and then the color image is fixed by a fixing device (not shown). .

Problems to be Solved by the Invention However, in the transfer device of such a conventional color copying machine, since the conveyance body for the transfer paper is constituted by the conveyance belt 4, it is necessary to avoid problems due to the flexible nature of the belt. There is a problem in that the so-called belt creep causes color misregistration when three colors of toner are superimposed on a sheet of transfer paper. Furthermore, in the conventional apparatus, cyan, magenta, and yellow toner images are transferred onto the horizontal surface of the conveyor belt 4 by independent photosensitive drums 5 to 7.
There was a problem in that the arrangement of the apparatus became long in a straight line, and the size of the apparatus itself was unavoidable.

An object of the present invention is to solve the above-mentioned problems, and to obtain color images without color shift even with a relatively small-sized device.

Means for Solving the Problems In order to solve the problems of the prior art, the present invention provides a semi-conductive resin film that circulates in close contact with a sheet of paper to which a toner image on a photosensitive drum is transferred at a transfer position; a plurality of electrodes arranged at regular intervals in the conveying direction of the semiconductive resin film on an insulating support provided on the inner peripheral surface of the semiconductive resin film; and an electrode on the upstream side of the transfer position. a plurality of suction brushes that slide on the inner peripheral side of the electrodes and electrostatically attract the transfer paper onto the semiconductive resin film by supplying a DC voltage to the electrodes; and when the electrodes move to the transfer position, In a transfer device of a color copying machine, the insulating support is attached to a rigid drum, and is equipped with a plurality of transfer brushes that slide on the inner peripheral side and perform transfer by applying a voltage of opposite polarity to the toner on the photosensitive drum. To provide a transfer device for a color copying machine, characterized in that it is shaped like a.

Effects According to the present invention, by energizing the suction brush at a predetermined timing, the paper to be transferred is attracted to an arbitrary position on the rigid drum, and the gap between the paper and the paper is fixed regardless of the size in the longitudinal direction of the paper. can be brought relatively close to each other, and the copying speed can be increased accordingly. In addition, at the transfer point of each photosensitive drum, each toner image on the drum is accurately transferred onto the paper by the transfer brush, and the rigid drum does not expand or contract, which reduces the paper conveyance distance. Since no errors occur, the toner images on each photosensitive drum can be superimposed in color at the preset positions, and the color image input on the photosensitive drum can be accurately transferred onto paper.

The rigid drum serving as the transfer drum is formed into a cylindrical shape, and therefore, it is possible to arrange multiple photosensitive drums circumscribing this drum, making it possible to effectively utilize the internal space of the copying machine main body, allowing the device to It is possible to reduce the size of the device itself.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings.

As shown in FIG. 1, the paper stacked in the paper feed cassette 1 is sent out by the paper feed roll 2, and the paper is supplied to the rigid body drum 35 as a transfer drum via the chute 42 by the transport rolls 40, 41. ing. As shown in FIGS. 2 to 4, this rigid drum 35 has a thickness of, for example, 0.5 mm.
A support 21 made of an insulating material is adhered to the back side of a semiconductive resin film 20 with a volume resistivity of 10 ^{to 10} Ω·cm, and an electrode 2 having a width of, for example, 1 mm is attached in the direction of conveyance of this support 21.
5 and 26 are arranged alternately with a gap of 1 mm,
Terminals 25a and 26a are exposed on the lower surface of the eaves of the support 21, respectively, as shown in FIG.

As shown in FIG. 5, on the inside of the support body 21 facing the terminals 25a, 26a of the electrodes 25, 26, there are terminals 25a and 2 at both ends of the rigid drum 35 in the width direction.
6a, suction brushes 43a and 4 that come into sliding contact with each other.
5a, 47a, 49a and suction brushes 43b, 45
b, 47b, and 49b are photosensitive drums 36 to 49b, respectively.
It is arranged upstream of No. 39 transfer points. The suction brushes 43a, 45a, 47a, 49a are grounded, and the other suction brushes 43b, 45b,
47b, 49b are DC power supply 27 and switch 28
A positive voltage is applied through the As shown in FIG. 1, transfer brushes 44, 46, 48, 50 are provided downstream of these suction brushes 43, 45, 47, 49 at positions facing each of the transfer drums 36-39.
are arranged on both sides facing the terminals 25a and 26a, and these transfer brushes are connected to a DC power source 29.
A predetermined positive voltage is applied via the switch 30.

The rigid drum 35 is rotated at a constant speed clockwise in FIG. 1 by a motor (not shown), and a transfer drum cleaner 51 is provided upstream of the chute 42 to clean the drum surface. . Adsorption brush and transfer brush 43~
50 is formed by implanting conductive fibers with a specific resistance of 10 ² Ω·cm and a length of 5 mm into a conductive support cloth.

To explain the operation of this embodiment, first, paper is guided from the paper feed cassette 1 to the chute 42 via the transport rolls 40 and 41, and the paper fed onto the transfer drum 35 at a predetermined timing is transferred to the transfer drum 3.
5 by suction brush 43. This first
In the suction part, when the switch 28 is turned on, a voltage of, for example, 1000 volts is applied from the DC power supply 27 to the suction brush 43b.
By applying a predetermined high voltage to the electrode 25 through the terminal 25a that is in sliding contact with the other suction brush 43a and grounding the electrode 26 of the terminal 26a that is in sliding contact with the other suction brush 43a, a potential difference is generated between the electrodes 25 and 26. A predetermined electric field pattern is generated on the surface of the semiconductive resin film 20, thereby attracting the paper onto the semiconductive resin film 20.

The paper adsorbed onto the semiconductive resin film 20 by the first adsorption section is conveyed to the first transfer section. In the first transfer section, a predetermined transfer voltage is applied from the DC power supply 29 to the transfer brushes 44a and 44b by turning on the switch 30 at a predetermined transfer timing.
Terminals 2 that come into sliding contact with the transfer brushes 44a and 44b
A transfer voltage is applied to the electrodes 25 and 26 of 5a and 26a, thereby transferring the yellow toner image on the photosensitive drum 36 onto the paper at the transfer point by electrostatic attraction.

In this case, the electrostatic latent image formed on the photosensitive drum 36 is imaged by, for example, a laser, and the electrostatic latent image formed is developed and visualized by a yellow developing roll (not shown). The photosensitive drum 36 at this time
The transfer point is set so that the rotation of the transfer drum 35 and the conveyance of the paper on the transfer drum 35 have a predetermined timing.

The paper onto which the yellow toner image has been transferred is conveyed to the second suction section, where it is moved by a second suction brush 45.
By applying electricity to a and 45b, the image is attracted onto the transfer drum 35 and transported to the next second transfer section. In the second transfer section, the magenta toner image formed on the photosensitive drum 37 at the transfer point is transferred at a predetermined timing by energizing the transfer brush 46, and the magenta toner image is transferred onto the yellow toner image. The image is overlaid with colors. Similarly, when transferring the cyan toner image and black toner image of the third and fourth photosensitive drums 38 and 39 onto the paper, the suction brushes 47 and 49
and the transfer drum 35 by the transfer brushes 48 and 50.
A cyan toner image from the photosensitive drum 38 and a black toner image from the photosensitive drum 39 are transferred onto the upper paper in superimposed colors.

In this way, the color image obtained by overlapping the four-color toner images on the photosensitive drums 36 to 39 is
The resulting color image is fixed by a fixing device (not shown) via a transport roll (not shown), and the resulting color image becomes an accurate color copy according to the image information without color shift because the transfer drum 35 is formed of a rigid drum.

If each of the photosensitive drums 36 to 39 disposed around the outer periphery of the transfer drum 35 is constructed of a xerographic photosensitive member, the diameter of the photosensitive drum is set to, for example, about 40 mm, and other components such as a developing device etc. The size of the copying machine itself can also be reduced accordingly, and if a semiconductor laser, for example, is used to expose the photosensitive drums 36 to 39, the size of the copying machine itself can be further reduced.

In this embodiment, unlike a conventional transfer drum, it does not have a gripper, so the transfer drum 35 can be set at any position on the transfer drum regardless of the relative position between the paper and the longitudinal direction of the paper. By setting the distance between sheets to a desired narrow interval regardless of the size of the paper, copying speed can be greatly increased.

Effects of the Invention According to the present invention, the paper transport body that transfers and transports the paper while circumscribing a plurality of photosensitive drums at transfer points is configured as a transfer drum made of a cylindrical rigid body. It is possible to obtain color copies with less misregistration, and because the photosensitive drum is disposed around the transfer drum, it is possible to further reduce the size of the apparatus. In addition, on the inner circumferential side of the transfer drum, a suction brush corresponding to the plurality of photosensitive drums and an electrostatic attraction based on the transfer brush are used to attract the paper onto the transfer drum and ensure the toner image is transferred at the transfer point. With this configuration, you can obtain color images with less color shift, and the copy speed can be significantly increased by allowing you to set the position of each sheet of paper that is conveyed one after another to any position depending on the timing of energizing the brush. It also has the effect of increasing your performance.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention, FIG. 2 is a partially cutaway sectional view of the transfer drum,
3 is a partial sectional view of the transfer drum, FIG. 4 is a bottom view showing the transfer drum, FIG. 5 is a circuit configuration diagram showing the power supply wiring in FIG. 1, and FIG. 6 is a schematic configuration diagram showing a conventional example. It is. DESCRIPTION OF SYMBOLS 1... Paper feed cassette, 20... Semiconductive resin film, 21... Support body, 25, 26... Electrode, 2
7, 29...DC power supply, 35...Transfer drum (rigid drum), 36-39...Photosensitive drum, 43,
45, 47, 49... Suction brush, 44, 46,
48, 50...Transfer brush.

Claims (1)

[Scope of Claims] 1. A semiconductive resin film that circulates in close contact with the paper to which the toner image on the photosensitive drum is transferred at the transfer position, and an insulating film provided on the inner peripheral surface of the semiconductive resin film. A plurality of electrodes are arranged on the support at regular intervals in the transport direction of the semiconductive resin film, and the inner circumferential side of the electrode slides on the upstream side of the transfer position, and a DC voltage is applied to the electrode. a plurality of adsorption brushes that electrostatically adsorb the transfer paper onto the semiconductive resin film; 1. A transfer device for a color copying machine equipped with a plurality of transfer brushes that perform transfer by supplying voltages of opposite polarity, wherein the insulating support is in the shape of a rigid drum.