JPH0562338B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a method for 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.
It is an object of the present invention to provide a method for simply and easily obtaining two-color image recording.

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 to form an electrostatic latent image that changes in response to successive print signals.

Next, colored toner is attached to the electrostatic latent image and developed by a developing device 6, and the toner image is transferred onto a recording paper 7 by a transfer device 8, and finally fixed to obtain a recorded image. The photoreceptor 1 is cleaned by a cleaner 9 and used again for image formation.

Images recorded using this method can be overlaid with data and forms (such as ruled lines on form paper) on the photoreceptor using software, but are only recorded in the same color.

However, in commonly used printing,
Forms and data are often printed in different colors, which is preferable for administrative purposes. Therefore, a printer capable of printing in such different colors has been desired.

In response to the above-mentioned needs, the present invention aims to provide a non-impact printing method that allows stable two-color printing using a simple device.
A method of forming images in response to exposure to information light using a photoreceptor with a conductive layer laminated on the back side of a photoconductive layer, and when forming a recorded image, a DC voltage is applied to the conductive layer. Then, the photoconductive layer of this photoreceptor is uniformly neutralized using a static eliminating member. Thereafter, the surface of the photoconductor is exposed to information light to form a latent image, and this latent image is further transferred to a first developing device using a first color toner, which is opposite to the photoconductor, or to a first developer using a first color toner. The image is developed by a second developer using a second color toner different from the color toner.

Therefore, when forming a recorded image using the first color toner, the photoreceptor is exposed to the information light of the first image, and at the same time, a developing bias of a value for development is applied to the first developing device. On the other hand, when forming a recorded image with the second color toner, a developing bias of a value that does not cause development is applied to the developing device.On the other hand, when forming a recorded image with the second color toner, the second image is The photoreceptor is exposed to information light, and a developing bias having a value for developing is applied to the second developing device, and at the same time, a developing bias having a value for not developing is applied to the first developing device.

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 of FIG. 1, 6a is a developer holding a negative toner of a first color (for example, black), 6b is a developer holding a negative toner of a second color (for example, red), and 10 is a developing device that holds a negative toner of a second color (for example, red). The illustrated example of the static eliminating member that keeps the surface potential of the photoreceptor 1 at a constant potential (for example, ground potential) is a conductive roller.

Reference numeral 11 denotes a power source that constantly applies a DC voltage (+EV) to the conductive layer 1b, and the power source 11 supplies the developing devices 6a and 6.
It is also used for the bias of b, and the interlocking switch 1
2 and 13, when the black toner developing device 6a operates for image recording, the voltage applied to the developing device 6a is 0, and the voltage applied to the developing device 6b is D, which is slightly higher than the applied potential +E to the conductive layer 1b (Fig. 3). ) is applied.

In addition, a red toner developer 6b is used for form recording.
If the bias is activated, the switches 12 and 13 are used to reverse the bias.

Next, the action will be explained.

(1) Recording of the first image such as characters The photoconductive layer 1a of the photoreceptor 1 is charged with the potential +E applied to the conductive layer 1b, but the static eliminating member 10
The static electricity is removed uniformly at the ground potential.

Figure 3 shows changes in the surface potential of the photoreceptor 1, with the vertical axis representing the potential V and the horizontal axis representing the time t, where V _D is the area not irradiated with the laser beam, and V _L is the area irradiated with the laser beam. Represents surface potential.

The process shown in FIG. 3 is a static elimination process using the static elimination member 10, and shows that the surface potential of the photoreceptor becomes the ground potential V _D regardless of the history.

This equivalent circuit is shown in FIG. The surface potential of the photoreceptor is _VD .

When data (image) is irradiated with the laser beam 3', the part of the photoconductive layer 1a that is irradiated with the laser beam becomes a conductive layer, so it becomes V _L with the same potential +E as the conductive layer 1b.
A latent image is formed by the potential contrast with the ground potential V _D of the portion not irradiated with the laser beam.

Next, the developing section is reached, and the bias of the developing device 6a is set to 0.
The black negative toner moves to and adheres to the V _L portion of high potential +E. The red negative toner in the developing device 6b does not participate in the development because its bias is set to a potential D (dotted chain line) higher than the potential of V _L +E.

The developed toner image is transferred to recording paper 7 by transfer device 8.
After fixing, the recording paper is sent to the transfer section again in synchronization with the photoreceptor for the next form recording with red negative toner.

The process shown in FIG. 3 represents the above-mentioned exposure, development, and transfer process, and the surface potential (ground) of the portion V _D that is not irradiated with laser light does not change during the process. The equivalent circuit diagram <D> in FIG. 4 represents the state.

The portion irradiated with laser light is the photoconductive layer 1a.
The surface potential of is equal to the polar current voltage +E applied to the conductive layer 1b (FIG. 4 <L>).

Black negative toner with a bias of 0 flies along the lines of electric force at the +E _VL portion, and the data is developed into a visible image.

The photoreceptor is cleaned with a cleaner 9 and charged with a static eliminating member 1.
0, and the process ends with the first data recording using black negative toner.

(2) Recording of a second image such as a form, etc. At the boundary of the process shown in FIG.
The bias of the developing device 6a is changed to D' (dotted line in the step in FIG. 3), which is equal to D, and the bias of the red negative toner developing device 6b is changed to C' (ground potential), which is equal to C.

After the static elimination step, the operations of the exposure, development, and transfer steps are the same as those in the first image recording described in (1) above. That is, red negative toner with a bias of 0 adheres to the +E V _L ' portion of the exposed second image (ruled lines and other forms in the embodiment).

In this way, the red foam image is recorded on the recording paper on which the black data image has already been recorded, forming a two-color recorded image.

The static eliminator 10 may be a static eliminator using a conductive liquid. Further, the toner may be either two-component or one-component.

Further, it is also possible to perform transfer onto recording paper immediately after red toner development without performing the transfer, cleaning, and charge removal steps after black toner development.

The combination of black and red toner colors in the above embodiment is merely an 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 above example 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 charging, toner, and latent image potential is opposite to that described above. Become.

Since the present invention does not use corona charging to form a latent image, it does not require a high voltage power source using a high voltage transformer for latent image formation. Therefore, a latent image can be formed with only one low-voltage transformer, and the low-voltage transformer can also be used as a developing device bias, and the power supply can be manufactured at low cost.

Using the same transformer makes it easy to fine-tune each voltage. Even with changes in the environment, there is no relative fluctuation between the developer bias and the potential of the bright and dark areas, and there is no occurrence of fog due to fluctuations in the dark area potential as occurs during corona charging. Furthermore, since the potential of the latent image is determined by the potential of the applied DC power supply, it is possible to always obtain a stable image with little environmental dependence.

Furthermore, since the photoconductive layer does not have a high potential, there is no fatigue thereof. Even if the photoreceptor 1 suddenly stops when a trouble occurs in the apparatus, there is no need to worry about high-pressure corona remaining on the photoreceptor as a memory.

Furthermore, a two-color recorded image can be obtained by simply changing the developer bias level. In addition, since only one information light source is required, there are various other features such as more space around the photoreceptor.

[Brief explanation of the drawing]

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 1 in the method of the present invention. , FIG. 4 is an equivalent circuit diagram of the latent image forming process. 1 is a photoreceptor, 1a is a photoconductive layer, 1b is a conductive layer,
3 is a laser light source, 6a and 6b are developing devices, 7 is recording paper, 10 is a static eliminating member, 11 is a DC power source, 12,
13 is a bias changeover switch for the developing units 6a and 6b.

Claims (1)

[Scope of Claims] 1. A method of forming an image in response to exposure to information light using a photoreceptor in which a conductive layer is laminated on the back side of a photoconductive layer, wherein when forming a recorded image, the conductive layer is With a DC voltage applied to the photoconductor, the photoconductive layer of the photoconductor is uniformly neutralized with a static eliminating member, and then the surface of the photoconductor is exposed to information light to form a latent image. a first developer using a first color toner, facing the body;
When a recorded image is formed using the first color toner, the photoconductor is developed with the information light of the first image. Exposure and first
A developing bias with a value for developing is applied to the second developing device, and at the same time, a developing bias with a value of not developing is applied to the second developing device, and when forming a recorded image with the second color toner, the above-mentioned method is applied. With a DC voltage applied to the conductive layer of the photoreceptor, the photoreceptor is exposed to information light of a second image, and at the same time a developing bias of a value for developing is applied to the second developing device, the first developing device is An electrophotographic recording method characterized in that a developing bias of a value that does not cause development is applied to the device.