JPS6167874A - Polychromatic printer - Google Patents

Abstract

PURPOSE:To uniform unevenly charged potential after development and to remove color mixture in the succeeding development by attenuating the potential of a background part on a recording body by using light obtained at the non- recording time of an exposing part after recharging the surface of the recording body. CONSTITUTION:A corotron 17 of which opening part is opened to a photosensitive body 1 is used as the recharger 17 after the 1st development and the photosensitive body 1 is charged by its corona discharge. To attenuate the potential of the background down to the potential of a toner A part by irradiating weak light, the leaked light of laser light at the 2nd exposure 20 is used. In this case, the output of a gas laser oscillator 21 is bent at its path by a mirror 22 and the laser light is turned on and off by a modulator 23. The modulated primary light is made incident upon a rotary mirror 26 by a mirror 25 and the reflected light is irradiated to the surface of a photosensitive drum 28 by a projection lens 27. The unmodulated 0-degree light is increased up to a level attenuating the potential of the background down to the potential of the toner adhering part A.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a one-shot multicolor printing device using an electrophotographic recording method, and is designed to uniformize uneven charge potential on a recording medium after development in the previous stage. The present invention relates to a multicolor printing device that prevents color mixing during subsequent development in this manner.

With the development of information processing equipment, the performance of printing equipment, which is the output means, must also improve, and electrophotographic methods are being developed to print at high speed and with high quality in order to express more information in a more visible manner. started to be used.

An example of an electrophotographic recording system is a laser printer as shown in FIG. The surface of the dielectric layer of a photosensitive drum (hereinafter referred to as drum) l, whose basic components are a conductive support and a dielectric layer, is uniformly charged positively or negatively in the pre-charging section 2, and then exposed to laser light in the next exposure section 3. irradiation to form an electrostatic latent image on the drum 1. After the electrostatic latent image is developed with toner in the developing section 4, the paper 6 is pressed against the drum 1 in the transfer section 5, and the toner image on the drum 1 is transferred onto the paper 6 by the transfer device 7, and then fixed by the fixing device 8. do. Further, the residual electric charge on the surface of the drum 1 is removed by the neutralizing lamp 9, the residual toner on the drum is cleaned by the cleaning section 10, and the drum is charged again by the pre-charging section 2 and the process is repeated.

Although one color is printed with the above device, multicolor printing can be achieved by, for example, arranging two of the above devices and developing one color at a time, and by continuously bussing the paper 6. However, this method requires a large apparatus, so in order to make it faster and more compact, there is an l-process multicolor printing apparatus shown in FIG. 7 in which each color is developed in one process.

Although FIG. 7 shows an example of the case of two colors, the invention is not limited to this. In the figure, 11 is a recharging part, 12 is a second exposure part, 1
3 is a second developing section, and except for this, the process is the same as the electrophotographic process described above, so sections 11, 12, and 13 will be explained here. In the case of the generally used reversal development process (where the charge is removed from the area exposed to light and toner is attached to the removed area), the potential after the first development by the developing section 4 is as shown in FIG. The potential on the body is uneven. The reason why the potential of the toner A adhesion area is low is that saturation development is not performed during development. When it is recharged in this state 11, exposed in the second exposure section 12, and developed in the second development section 13, the toner A of the first development is
It will also be developed on top of the image, resulting in color mixture and an unsightly image.
An image without color mixture is desired.

[Conventional technology]

Conventionally, as a method of preventing color mixture, a grid-type corotron was used for recharging 11 so that the potential after the first development was uniform after the developing section 4, as shown in FIG. 9 (see FIG. 7). be. 10(a) and 10(b) show a grid type corotron, in which thin wires 15 are stretched at appropriate pitches in the opening facing the photoreceptor 1 of the corotron. Note that 16 indicates an insulator. B indicates a corona electrode.

The potential on the photoreceptor after the first development is uneven as shown in FIG. , corona discharge and return to the original potential (60 in the figure)
In this method, the temperature is returned to 0 V'j and second development is performed to prevent color mixing.

Another method for preventing color mixture is to combine light irradiation from a corotron 17 and a lamp 18, as shown in FIG. 11, instead of using a grid-type corotron for recharging. There is also one that eliminates the afterglow in Figure 8 and makes the charged potential more uniform.

[Problem that the invention seeks to solve]

The method of equalizing the charged potential using the grid-type corotron shown in Fig. 9 is a complicated structure in which the grid-type corotron has thin grid wires stretched across the opening and the corona electrode B inside. There were problems in that it was difficult to clean and could not be easily maintained by anyone.

Further, in the method of equalizing the charged potential by combining the corotron 17 and the lamp 18 shown in FIG. 11, the corotron 14 can be easily cleaned because there is no grid in the opening.

However, it is necessary to irradiate the lamp 18 with a very weak light intensity, and lamps generally have a deterioration in light intensity and it is difficult to adjust the light intensity by feedback.
The problem is that it lacks credibility.

[Means for solving problems]

The above-mentioned problem is solved by using a method to prevent color mixing in a multi-color printing device, in which the recording medium is recharged by corona discharge for the second development performed after the first development, and then the recording medium is recorded in the exposed area where the next latent image is formed. The present invention is characterized in that the background potential on the recording medium is attenuated by using the light intensity during non-recording between the light intensity during non-recording and the light intensity during non-recording, and the potential of the toner-adhered area is made uniform. Achieved by color printing equipment.

[Effect]

By raising the unevenness of the potential on the recording medium after the first development by corona charging, and then using the writing light during non-recording to eliminate the background potential to the level of the toner image potential developed in the previous stage. Color mixing is prevented by making the charged potential uniform and preventing toner from adhering to the toner image developed in the previous stage in the next stage of development. Also, since the corotron does not have thin wires in the opening, it is easy to clean the corotron.

〔Example〕.

Hereinafter, the gist of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a sectional view illustrating an embodiment of the present invention, FIG. 2 is a diagram showing the potential on the recording medium after the first development in FIG. 1,
FIG. 3 is a perspective view of an optical system used in the present invention, and FIG. 4 is a perspective view of another optical system used in the present invention. Note that the same reference numerals throughout the figures indicate the same objects.

In FIG. 1, the present invention first describes a recharging device 1 after first development.
Step 7: Charge the photoreceptor 1 by causing corona discharge using a corotron with an open opening facing the photoreceptor. Compared to the slit control type, this type of corotron has a simpler structure and is easier to maintain such as cleaning. However, the charging potential cannot be made uniform and the controllability of the charging potential is poor, and the potential after recharging is It will look like Figure 2. After this, the charged potential can be made uniform by irradiating weak light to attenuate the background potential to the potential of the toner A portion. Since the area with the steepest slope is the area to be used, the amount of irradiation light must always be within a certain area.

For this reason, in the present invention, the leakage light (light during non-printing) of the second exposure 20 by laser light is used instead of a lamp whose light intensity easily changes.

For example, in the case of a gas laser, the optical system is as shown in Figure 3, and the laser oscillator 21 usually does not have an oscillation stop.
The mirror 22 bends the path, and the deflection modulator 23 turns on the relay' and turns it Ql'F. The light when not modulated is called 0th order light, and the modulated light is called 1st order light, and the 1st order light is used for writing. The slit 24 has eight circumferences so that the first-order light passes through but the zero-order light does not pass through. Depending on how the slit 24 is adjusted, some zero-order light may also leak out when the slit 24 is OFF. The primary light is incident on the rotating mirror 26 by the mirror 25, and the reflected light is irradiated onto the angry light drum 28 by the projection lens 27.

In general, compared to the primary light for writing, the zero-order light of leakage light (non-printing light) is regulated to be sufficiently small so that it does not have a light history even if the same area is repeatedly irradiated when the photoreceptor is stopped. . In the present invention, the amount of zero-order light is made large enough to attenuate the background streetcar to the potential of the toner adhesion area A.

Note that a shutter 29 may be provided at the exit of the laser oscillator 21 or the like in order to prevent the above-mentioned adverse effects from occurring when the photoreceptor is stopped for a photoreceptor that is prone to light history.

The first-order light of the writing light and the zero-order light of the leakage light can be set to the same ratio, and since the writing light is generally controlled to maintain a constant light amount, stable leakage light can be easily obtained.

In the case of a semiconductor laser, the optical system is as shown in FIG. 28.

The information required at that time is obtained by controlling the semiconductor laser 19 to turn on and off while optically scanning. When ON, normal writing is performed and OI? At F, the potential of the photosensitive drum 28 is regulated at a level that does not lower it.

In the above-mentioned semiconductor laser control, the semiconductor laser control circuit can adjust the leakage light when the semiconductor laser is OFF to reduce the background potential to the level of the toner image A potential developed in the previous stage.

As described above, by using the corotron 17 for recharging after the first development, there is no slit in the opening facing the photoreceptor 1, so maintenance such as cleaning is easy and the structure is simple.

The irregularities in the potential on the photoreceptor after development (see Figure 8) are resolved by raising the potential once again with the corotron 17 for recharging as shown in Figure 2, and then increasing the background potential in the previous stage with the leakage light of the laser beam. By removing the charge to the level of the potential of the developed toner image A, the charged potential can be made uniform, and toner can be prevented from adhering to the toner image in the next stage developing section 12 (color mixing can be prevented).

〔Effect of the invention〕

As explained above, according to the present invention, uneven charge potential after development can be made uniform by providing a corotron recharging device that is easy to maintain and by obtaining stable leakage light from a latent image writing light source without taking up extra space. This has a sufficient effect in preventing color mixing in the next stage of development.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention, FIG. 2 is a diagram showing the potential on the recording medium after the first development in FIG. 1, and FIG. 3 is an example of an optical system used in the present invention. FIG. 4 is a perspective view of another optical system used in the present invention. Figure 5 is a diagram showing the sensitivity characteristics of the photoreceptor, Figure 6 is a diagram explaining the outline of a laser printer, Figure 7 is a diagram explaining a conventional multicolor printing device, and Figure 8 is a diagram after the first development. Figures 9 and 11 are diagrams showing the electric potential. Figures 9 and 11 are diagrams of a conventional device that aims to equalize the charged potential. Figure 10 is a diagram showing a bullitt type corotron. (a) is a front view, (b) FIG. 10 is a cross-sectional view of FIG. 10(A). In the figure, 1 is a photoreceptor, 2 is a pre-charging section, 3 is an exposure section, 4 is a development section, 12. 20 is a second exposure, 17 is a corotron, 19 is a semiconductor laser, 21 is a laser oscillator, 22. 25 is a mirror, 23 is a modulator, 24 is a slit, 26 is a rotating mirror, 27 is a projection lens, 28 is a photosensitive drum, 29 is a mirror, 30 is an Fθ lens, and 31 is a reflecting mirror. '#l Utaken 2z IIr-3 呵f--t-A'+sfT ￥-i war'11.74 Ura δ drunken ban 9th

Claims (1)

[Claims] A multicolor printing apparatus using an electrophotographic method, which is equipped with two or more color developing devices and color mixing prevention means between each of the developing devices, wherein the color mixing prevention means is used to prevent subsequent development performed after the previous development. Therefore, after recharging the recording medium with corona discharge,
Of the light amount during recording and the light amount during non-recording in the exposed area that forms the next latent image, the light amount during non-recording is used to attenuate the background potential on the recording medium and make it uniform with the potential on the toner-attached area. A multicolor printing device that is characterized by the ability to: