JPS608853A - Two-color electrophotographic recording method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention provides two-color image recording when recording optical information such as a laser beam, an LED element array, a combination of a light source, and a liquid crystal shutter using electrophotographic technology. The purpose is to provide a simple and easy way to obtain information.

FIG. 1 illustrates a laser beam printer as an example. The photoreceptor 1 is uniformly charged by a charger 2. Next, a light beam 3' emitted from a laser light source 3 is scanned and exposed onto the photoreceptor by a scanner 4 and a lens 5, thereby forming an electrostatic latent image of an image that changes in accordance with successive printing patterns.

Next, colored toner is applied to the electrostatic latent image in the developing device 6 and developed, and the toner image is transferred to the recording paper 7 in the transfer device 8, and finally fixed to form a recorded image. (■) be. The photoreceptor 1 is cleaned by a cleaner 9 and used again for image formation.

Images recorded in this way contain data and forms (
Although it is possible to print lines (such as ruled lines on form paper) on the photoreceptor using software, they are only recorded in the same color.

However, in commonly used prints, the form and data are often printed in different colors, which is preferable for business processing. Therefore, a printer capable of printing in such different colors has been desired.

In response to the above-mentioned needs, an object of the present invention is to provide a non-impact printing method that can perform stable two-color printing using a simple device. In the photoreceptor, a conductive layer is laminated on the back side of a photoconductive layer, and when recording a first image, a DC voltage of a first polarity is applied to the conductive layer, and a first polarity is applied to a first color toner developer. Apply polar DC voltage bias,
In addition, when recording a second image by keeping the static eliminating member of the photoreceptor at a potential lower than the 18i 7heyas voltage, a DC voltage of a second polarity opposite to the first polarity is applied to the conductive layer. At the same time, a DC voltage of the second polarity /Heas is applied to the color toner developer of ff12, and the first and second 2 characterized by switching the polarity of the DC power supply.
This is a color electrophotographic recording method.

FIG. 2 shows an example of an apparatus for carrying out the method of the present invention, in which a photoreceptor 1 consists of a photoconductive layer 1a on the front surface and a bipolar conductive layer 1b on the back surface. 3' is the modulated laser beam shown in FIG. 1, 6a is a developer that holds a first color toner (for example, black), 6b is a developer that holds a second color toner (for example, red), and 7 is a recording paper. , 9 is a cleaning device, l
O is a transfer fixing device.

Reference numeral 11 denotes an antistatic member that maintains the surface potential of the photoreceptor l at a constant potential, and although the illustrated example shows a conductive roller, it may be one using a conductive liquid or the like. 12 is a DC power supply having three levels, 12a is positive, 12b is negative, and 13 and 14 are power supplies 12a and 1.
If 13 selects 12a with the changeover switch 2b, 14 will also select 12a, and if 13 selects 12b,
14 is also configured to select 12b.

Further, in the positive DC power supply 12a, in descending order of potential, (1) is the first polarity applied potential (+EV) to the conductive layer 1b, (2) is the first polarity bias potential (+EV) for black toner development @ 6a, and (2) is the +EV The electric potential of the static eliminating member 11 (for example, OV) is set in the order of lower electric potential (OV). Negative DC power supply 1
In order of decreasing potential of 2b, (2) is the second polarity applied potential (-EV) to the conductive layer 1b, (2) the second polarity bias potential (-ev) to the red toner developer 6b, and (2) is the -e.
11 of the potential (for example, OV) of the static eliminating member 11 higher than v
It is set to 11.

In the above configuration, an image is formed by the following process.

Recording data such as characters as the first image (1) When the selector switches 13 and 14 are set to the DC power supply 12a,
The static eliminating member 11 is at ground potential (OV), and the conductive layer 1b is at +E.
, the photoconductive layer 1a is charged with +E, but its surface potential is at ground potential.

Figure 3. Curve of change in surface potential of photoreceptor l (vertical axis shows potential -
(The horizontal axis represents the JP-A t), (L step during one drum rotation period A and during the print signal stop period), (Fig. 4 equivalent circuit (I) of the latent image forming process, B is the photoreceptor's equivalent circuit (I)), surface potential).

(2) The photoreceptor is irradiated with laser light 3 that changes in response to sequential print signals to form a latent image (data). Photoconductive layer 1a in the portion VL hit by light (solid line in FIG. 3)
becomes a conductor, so it has the same polarity and the same potential as the conductive layer ib.
becomes. (Fig. 3 2 steps during the laser beam irradiation period) (
Figure 4 (II) <VL>).

Since the surface potential of the portion VD (broken line in FIG. 3) which is not irradiated with the laser is OV (FIG. 4 (IF) <VD>), a latent image is formed by the contrast between VD and VL.

(3) The black negative toner of the developing device 6a to which a bias of 10 ev is applied adheres to the VL portion and is developed (step 3 in period A in FIG. 3).

In this case, a bias of -ev is applied to the developing device 6b,
Since the red toner is positive, it does not participate in development.

(4) With the subsequent rotation of the photoreceptor 1, transfer, pressure stabilization, and (
The data recording process is completed by completing one revolution through the 5 steps of period A in FIG. 3, which are the 4 steps in period A in FIG.

The form recording paper 7 as the second image is sent again to the position of the transfer fixing device 10 in synchronization with the photoreceptor 1.

(1) Simultaneously with the start of static elimination by the static eliminating member 11 at point A in FIG. 3 when the above-mentioned one rotation is completed, the changeover switches 13 and 14 are switched to the negative DC power source 12b side.

At this moment, the surface potential of the photoconductor l is ground potential at the static eliminating member 11, and the conductive layer 1b is -E (1 step during the A period in Figure fJS3 and during the print signal stop period) (Equivalent circuit (■) in Figure 4) 2) Irradiate the form of the original onto the photoreceptor with laser light 3'. The photoconductive layer la of the portion VL exposed to light is -EV
(Figure 3: Laser light irradiation period 2).

Since the surface potential of the portion VD not irradiated by the laser beam is 0, a latent image is formed in contrast with -EV of the portion VL irradiated by the light.

(3) The VL portion is developed with the red positive toner of the developing device 6b to which a bias of -ev is applied (3 steps in period A' in FIG. 3).

/ (4) The following 4 steps during the period A in FIG. 3 include transfer, pressure fixing, and cleaning to the static elimination member 11, and the 5 steps during the period 7' in FIG. is recorded with red toner. That is, a two-color recorded image is formed.

The combination of black and red toner colors in the above embodiment is just one example, and may be applied to toners of various other colors such as blue, sepia, and others. Furthermore, the order of image formation is also arbitrary.

In addition, the example L shows an example in which an N-type material such as CdS is used as the photoconductive layer, but if a P-type material such as selenium is used, the polarity of the charge, toner, and latent image potential will be opposite to the above. become.

According to the present invention, the conductive layer 1b of the photoreceptor l in which the photoconductive layer 1a and the conductive layer 1b are superposed, and the first color toner developer 6
a. The apparatus is simple because two-color recorded images can be obtained by simply switching the polarity of the DC voltage power supply applied to the second color toner developing device 6b. Further, in this case, the power source is inexpensive because a high voltage power source such as that used for corona discharge is not required. Furthermore, since only one information light source is required, there are moderate structural advantages such as freeing up space around the photoreceptor.

Furthermore, since the photoconductive layer 1a does not have a high potential, there is no fatigue thereof. Furthermore, even if the photoreceptor 1 suddenly stops when a trouble occurs, there is no risk of high-pressure corona remaining on the photoreceptor as a memory. Unlike corona charging, there is no attenuation of the potential due to the discharge of the applied corona, so there is little environmental dependence.Furthermore, the potential of the latent image for both colors is determined by the potential of the DC power supply, so it is always stable. Its functional characteristics are also remarkable.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional laser beam printer, FIG. 2 is a schematic diagram showing an example of an apparatus for carrying out the method of the present invention, and FIG. 3 is a curve diagram showing changes in the surface potential of the photoreceptor l in the present invention. Figure 4 is an equivalent circuit of the latent image forming process. la is the photoconductive layer of the photoreceptor 1, lb is the conductive layer, 3 is the laser beam, 6a and 6b are the developing devices, 7 is the recording paper, 10 is the transfer/fixing device, 11 is the neutralizing member, and 12a is the direct current voltage. Power supply, 12. b is a negative DC voltage power supply, and 13 and 14 are power supply selector switches. Figure 3 Figure 4 (I) (If) (I[) Figure 1? Figure 2 ■hie)

Claims (1)

[Claims] (1) In a method of forming an image in response to exposure to information light, a photoreceptor is used in which a conductive layer is laminated on the back side of a photovoltaic layer, and when recording a first image, a first polarity is applied to the conductive layer. Applying a direct current voltage and applying a bias of a first polarity direct current voltage to the first color toner developer, and also keeping the static eliminating member of the photoreceptor at a potential lower than the first polarity bias voltage, and forming a second image. When recording, a DC voltage of a second polarity opposite to the first polarity is applied to the conductive layer, and a DC voltage bias of the second polarity is applied to the second color toner developer. , and a two-color electrophotographic recording method characterized in that the DC power sources of the first and second polarities are switched so as to keep the static eliminating member of the photoreceptor at a lower potential than the bias voltage of the second polarity.