JPS61249065A - Image forming device - Google Patents

Abstract

PURPOSE:To transfer developer images to the top and reverse surfaces of a transfer material simultaneously by forming developer images which differ in polarity on a couple of recording body belts, clamping surfaces of the both closely across the transfer material, and applying an electric field. CONSTITUTION:The couple of recording body belts 2 and 3 are extended rotatably among rollers 4a-4c and 5a-5c symmetrically about a transfer paper conveyance path 1 and a transfer position T is set where the belts 2 and 3 face each other closely. Those belts 2 and 3 are formed plural layers and a surface layer 2a is outside. Positive and negative bias voltage applying power sources 6 and 7 are connected to the 1st and the 2nd conductive layers 2b and 2d of the belt 2. Similarly, negative and positive bias voltage applying power sources are connected to the 1st and the 2nd conductive layers of the belt 3. Then, optical writers 10 and 11 which irradiate light as an image signal are provided at the inside of the belts 2 and 3 of the path 1 and toner images are formed at the outside of the belts 2 and 3 according to image signals.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a double-sided image forming apparatus, and more particularly to a double-sided image forming apparatus applicable to recording devices such as printers and copying machines.

As for electrophotographic copying machines, double-sided copying machines that produce images on both the front and back sides of transfer paper have already been put into practical use; After forming and fixing the image, the transfer paper is turned over and the same process is performed again on the other side to obtain an image. According to such a method, it takes more than twice as much time to obtain a double-sided image as compared to a single-sided image, and a mechanism for reversing the transfer paper is required, making the apparatus complicated and expensive.

Hiroshi lj The present invention has been made in view of the above points, and an object of the present invention is to provide an image forming apparatus that has a simple structure and can obtain double-sided images in a short time.

In order to achieve the above object, the present invention provides a transfer material transport path for transporting a transfer material along a predetermined path, and a surface layer, a first conductive layer, a photoconductive layer, and a translucent layer, respectively. It is formed by laminating a second conductive layer and a translucent base layer, and is rotated so that each of the surface layers faces outward and a portion of both surface layers approaches each other via the transfer material conveyance path. a pair of endless recording media stretched so as to be movable; a first voltage applying means for applying a bias voltage of opposite polarity to both of the first conductive layers; a second voltage applying means for applying bias voltages having polarities opposite to each other and having opposite polarities to the voltage applied to the first conductive layer in each recording medium; and a developing image charged to opposite polarities to the surface of each recording medium. The present invention is characterized by having a pair of developing means for supplying an agent, and a pair of optical recording means for irradiating each recording medium with light corresponding to an image signal.

Hereinafter, a specific explanation will be given based on one embodiment of the present invention. FIG. 1 is a schematic diagram showing one embodiment of the present invention. In FIG. 1, a conveyance path 1 for conveying the transfer paper is set up, and the transfer paper t is conveyed along this in the direction of the arrow at a predetermined speed. A pair of recording belts 2 and 3 are arranged symmetrically across the transfer paper conveyance path 1, each of which has a plurality of rollers 4a to 4c.
, 5a to 5c so as to be rotatable. In this case, one roller 4a, 5 of the plurality of rollers 4a to 4c, 5a to 5c supporting each recording belt 2, 3
a are arranged to face each other via the transfer paper conveyance path 1, and therefore, each recording body belt 2, 3 is close to the transfer paper conveyance path 1 at this opposing position, and a transfer position T as described later is established. It is formed. Also, each recording belt 2, 3
The directions of the rotational forces are set so that they move in the same direction in the transfer area T along the transfer paper conveyance direction.

For example, the recording belt 2 of the pair includes a surface layer 2a, a first conductive layer 2b, a photoconductive layer 2c, a transparent second conductive layer 2d, and a transparent base layer 2e, which are sequentially laminated as shown in FIG. It is formed into a five-layer structure. The dark resistance value Rpd, the bright resistance value Rpl of the photoconductive layer 2c, and the ground resistance values Rc1°Re of the first and second conductive layers are set to satisfy the following relationship.

Rpd ＞ ＞ Rax ＞ ＞ Rpl ＞ ＞ Re
2+Old++■Here, it is desirable that the layer thickness of the surface layer 2a is as thin as possible, and there is no particular restriction on the material as long as it is a normal dielectric material. Further, the material of the photoconductive layer 2c is preferably one having a fast photoresponse speed, and may be any material as long as it has sensitivity appropriate to the wavelength of the irradiated light.

The second conductive layer 2d may be formed of a translucent electrode material such as an ITO film, and in combination with the translucent base layer 2e, for example, a product under the trade name "High Beam" (manufactured by Toshi) can be used. It is. The other recording belt 3 is also formed in the same manner.

In this example, a pair of recording belts 2.degree. 3 constructed as described above are stretched between three rollers 4a to 4c and 5a to 5c so that the surface layer 2a of each belt is on the outside. and 1
For example, the first and second conductive layers 2b of one recording belt 2,
As shown in FIG. 3, first and second bias voltage application power supplies 6 and 7 of positive and negative polarities are connected to 2d to apply bias voltages of the respective polarities. Further, as shown in FIG. 5, the other recording belt 3 has a first belt.

Negative and positive bias voltage application sources 8 and 9 are connected to the second conductive layers 3b and 3d, respectively, to apply bias voltages of the respective polarities. That is, a pair of recording belts 2
, 3 corresponding pairs of first and second conductive layers 2a, 3a.
Bias voltages of opposite polarity are applied to 2d and 3d. If this is summarized and illustrated, it will look like FIG. 7.

In FIG. 1, optical writers 10 and 11 for irradiating light as an image signal are respectively disposed at appropriate positions near the inner side of the moving path of each recording belt 2.degree. Each optical writer 10, 11 includes, for example, a laser, an LED array, an LC
Light sources 10a and 11a that can irradiate each pixel on a recording belt such as an S array, and light sources 10a and 11a that can appropriately guide the irradiated light and make it enter the transparent base layers 2a and 3e on the inner surface of each recording belt 2.3. Optical systems 10b, 11. It is composed of b.

Developing units 12 and 13 are respectively disposed on the outside facing each optical writer 10 and 11 with the recording belts 2 and 3 interposed therebetween. Use magnetic toner. Of the pair of developing devices 12 and 13, for example, the developing device 12 disposed on the recording belt 2 is approximately the fifth developing device.
As shown in the figure, a developing sleeve 12a is grounded and rotatably supported at a position where a part of its peripheral surface can move in the same direction and come into contact with the surface layer 2a of the recording belt 2;
A hopper 12b that stores toner and replenishes the surface of the developing sleeve 12a in appropriate amounts, regulates the layer thickness of the toner carried on the sleeve 12a, and is tribo-electrified to the same positive polarity as the bias voltage applied to the first conductive layer 2b. The doctor blade 12c is made up of a doctor blade 12c. In this example,
A magnet roller 12d is disposed coaxially and rotatably within the sleeve 12a, thereby efficiently conveying the magnetic toner.

In the developing device 12 configured as described above, the hopper 1
The toner supplied from the sleeve 12b is frictionally charged to a positive polarity by the blade 12c and is uniformly thinned, and as the sleeve 12a rotates, the developing device! D, where the toner is electrically transferred to the surface layer 2a of the recording belt according to the image signal.
A toner image is formed by suction upward. The developing mechanism is as follows.

By the way, the recording belt 2 configured as described above has the following features:
An equivalent circuit as shown in FIG. 4 is formed. In FIG. 4, Cs and Cp represent the surface layer 2a and the photoconductive layer 2c, respectively.
represents each capacitance.

Here, if the applied voltages of the first and second bias power supplies 6 and 7 are respectively V and V2, the surface potential Vs of the surface layer 2a is Vs=1/(Rc, +Re, +Rp) X((Rp+Rcz )Vx RCzV2)" (2). Therefore, the surface potential Vsd in the dark area where light is not irradiated by the optical writer 10 is expressed as R in equation (2).
When P is set to Rpd and formula 1) is taken into account, Vsd value + V engineering (3) is obtained. Furthermore, since Rp becomes Rpl, the surface potential V s ] in the bright area similarly becomes Vsl'' Vz (4).

As described above, since the potential distribution of the surface layer 2a at the development position is formed according to the image signal, as shown in FIG.
Among the positively charged toners conveyed to the development position, toner corresponding to dark areas is repelled, and toner corresponding to bright areas is attracted and adheres to the surface layer 2a. In this manner, a toner image is formed on the surface layer 2a of the recording belt 2 in accordance with the image signal. The toner remaining on the sleeve 12a without being subjected to development is collected into the hopper 12b as the sleeve 12a rotates and is reused.

In the other recording medium belt 3, as shown in FIG. 1, a developing device 13 having the same structure as the developing device 12 is disposed at a symmetrical position with respect to the transfer paper conveyance path 5 in this example, and is placed at a developing position. D' is formed. However, in this case, the materials of the doctor blade 13c and the toner are selected so that the thin toner layer conveyed to the developing device 11D' is negatively charged by friction as shown in FIG.

Further, an equivalent circuit shown in FIG. 6 is formed on the recording belt 3. This equivalent circuit is the first equivalent circuit of the recording belt 2 shown in FIG.

The only difference is the polarity of the second bias power supply 8.9.
The other configurations are the same. Therefore, the surface potential Vsj of the recording body belt surface layer 3a at the development position D'' is as follows: Vs'=1/(Rc1+Re2+Rp)x(Rc,v,
-(Rp+Rc,)v,)-(5), and the surface potential Vsd' in the dark area is Vsd'=-Vl...
......(6) The surface potential Vsl' in the bright area is: V sl''' + V2... (7)
becomes. Development position D' where the potential distribution is formed as described above
Since the negatively charged toner is conveyed as described above, the toner is selectively attracted to the bright areas of the surface layer 3a, and a toner image is formed according to the image signal light irradiated by the optical writer 11. is formed.

Toner images of different polarities formed on the surface layers 2a, 3a of each recording belt 2, 3 are conveyed to a transfer position T as they rotate. The transfer operation at the transfer position T is schematically illustrated in FIG. In Figure 7,
The surface potential Vsd of the dark area of the recording belt 2 is a negative potential from equation (4), and the surface potential Vsd' of the recording belt 3 is given by (6).
Since the surface layer 2a is formed at a positive potential from the formula,
, 3a, a strong electric field is formed vertically in the figure. Therefore, the positive layer attached to each surface layer 2a, 3a,
A force acting on the negative toner causes the transfer paper to move upward from the surface layer 2a, 3a of each recording belt due to the electric field.

As a result, the toner is simultaneously transferred to both the front and back surfaces of the transfer paper t, and each toner image is transferred. The transfer paper t onto which the toner image has been transferred is conveyed in the direction of the arrow along a conveyance path 1, and the double-sided image is fixed through a fixing step (not shown). In this way, double-sided images can be easily and quickly obtained on both sides of the transfer paper t.

(L-Kaku) As detailed above, according to the present invention, developer images of different polarities are formed on a pair of recording belts, and an electric field is applied to the surfaces of both belts at a transfer position where they are brought close to each other with a transfer material in between. By acting on the developer, it is possible to transfer the developer image to both the front and back sides of the transfer material at the same time.Therefore, desired images can be easily and quickly formed on both sides of the transfer material. It goes without saying that the present invention is not limited to the specific embodiments and that various modifications can be made within the technical scope of the present invention.For example, the developer used is not limited to a magnetic component type, but may be a It is also possible to use magnetic or two-component developers.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, FIG. 2 is a schematic sectional view showing the structure of the recording belts 2 and 3, FIG. 3 is a schematic diagram showing the developing position, and FIG. Figure 4 shows recording belt 2.
5 is a schematic diagram showing the developing position D', and FIG. 6 is a circuit diagram showing an equivalent circuit representing the electrical configuration of the recording belt 3.
FIG. 7 is a schematic diagram showing the transfer position T. (Explanation of symbols) 1: Transfer paper conveyance path 2.3: Recording belt 6.7, 8, 9: Bias voltage application power source IQ, 11
: Optical writer 12.13: Developer patent applicant Rico Co., Ltd. - No. 21!1 = %4[! 1 6th (!l

Claims (1)

[Claims] 1. A transfer material conveyance path that conveys the transfer material along a predetermined path, and a surface layer, a first conductive layer, a photoconductive layer, a transparent second conductive layer, and a transparent base layer, each of which is laminated. a pair of endless recording media, each of which is rotatably stretched so that each surface layer faces outward and a portion of both surface layers approaches each other via the transfer material conveyance path; a first voltage applying means for applying bias voltages of opposite polarity to both of the first conductive layers; a second voltage applying means for applying a bias voltage of opposite polarity to the voltage applied to the layer; a pair of developing means for supplying a developer charged with opposite polarities to the surface of each of the recording media; An image forming apparatus comprising a pair of optical recording means that irradiates a medium with light corresponding to an image signal.