JPH0336229B2 - - Google Patents

Description

Detailed Description of the Invention (A) Technical Field of the Invention The present invention relates to a multicolor recording device such as an electrophotographic recording device or an electrostatic recording device, and particularly relates to a recharging process for obtaining good multicolor recording. This invention relates to an improved multicolor recording device.

(B) Prior Art and Problems FIG. 1 is a diagram for explaining a conventional two-color recording device. FIG. 2 is a diagram showing the potential level on the photoreceptor of the two-color recording apparatus shown in FIG.

In the figure, a photoreceptor 1 which is an endless image carrier
The initial charger 2 uniformly charges the top. The potential at this time is set to V _S1 as shown in FIG.
Next, as shown in FIG.
An image corresponding to the color (A color) is exposed. At this time, the potential of the exposed portion is attenuated to approximately 0 [V].
After that, a first reduction is performed. As shown in FIG. 2, a two-component magnetic brush developer 4 using a developer with a positive toner charge is used for the first color (color A), and the developing bias voltage V _B1 is set slightly higher than V _S1 . Set it to a low value and perform development. Then, as shown in FIG. 2, toner adheres to the portion from which the charge has been removed. Next, recharging is carried out by the recharging device 5 as shown in FIG. 2, thereby increasing the potential on the photoreceptor 1 and decreasing the unsaturated potential ΔV caused by the first development. This is because in the one-component magnetic toner development used in the second development, the required latent image strength to obtain a sufficiently high density recording is greater than in the two-component magnetic brush development method. This prevents magnetic toner from adhering to unsaturated areas of the first development. Let the potential on the sight body obtained by recharging be V _S2 . Next, as shown in FIG. 2, a second color (B
Expose the image corresponding to the color (color). At this time as well, the potential of the exposed portion is attenuated to approximately 0 [V]. After that, a second development is performed. This is 1 of the second color (B color)
Development is performed using a one-component magnetic toner developer 7 using component magnetic toner, with the developing bias voltage V _B2 set to approximately the same value as V _S2 . Then, as shown in FIG. 2, toner adheres to the portion from which the charge has been removed.
A two-color toner image of A color and B color is formed on the photoreceptor 1. Thereafter, the toner image is transferred onto recording paper 9 by transfer device 8 . Next, one process is completed through the fixing of the toner image, the static elimination process 10, and the cleaning process 11 in the same way as in a normal electrophotographic process. This method allows good two-color recording.

For the sake of simplicity, a two-color recording device has been described as an example, but in such a device, when developing with B color toner by the one-component magnetic toner developer 7, the two-component magnetic brush imager is first developed. In step 4, the B color toner also adheres to the area where the A color toner has been developed, resulting in color mixture, which may deteriorate the recording quality.

The reason why such a phenomenon occurs is that when a photoreceptor with a large capacitance is used, even if recharging is performed by the recharging device 5 during the recharging process, the first
This is because the unsaturated potential ΔV during development is not sufficiently reduced.

In order to eliminate such defects, conventionally, as shown in FIG. 3, the entire surface is irradiated after the first development.
The present inventors have proposed a method in which the potential of the non-image area is attenuated to reduce the potential difference between the image area and the non-image area, and then recharging is performed. Although good two-color recording can be obtained with this method, it has the disadvantage that it adds the step of irradiating the entire surface, making the process complicated.

(C) Object of the Invention In view of the above-mentioned conventional drawbacks, the object of the present invention is to provide a multicolor recording device in which the potential difference between the image area and the background area (unsaturated potential ΔV) is removed by a simplified process, and color mixing does not occur. Our goal is to provide the following.

(D) Structure of the Invention The object of the present invention is to provide an endless image carrier, and a method of forming an electrostatic latent image on each of the image carriers arranged along the moving direction on the image carrier. a plurality of image forming means, a plurality of developing means provided corresponding to the image forming means and developing the electrostatic latent image formed on the image carrier using toners of different colors; Recharging means for recharging the image bearing member immediately before the image forming means other than the foremost image forming means with respect to the moving direction of the image bearing member among the plurality of image forming means, and This is achieved by providing a multicolor recording device characterized in that the recharging means is a scorotron, and the scorotron performs recharging in a corona discharge region accompanied by light emission.

(E) Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In the present invention, a scorotron is used as a recharging device. FIG. 4 shows the structure of this scorotron. A metal wire having a diameter of about 50 to 150 μm is provided as a corona wire 12 inside a grounded metal case 14, and a high voltage of 7 to 9 kV is applied. In addition, as a grid wire 13 at the opening of the metal case 14, the pitch is about 1 to 3 mm and the diameter is about 50 mm.
Multiple 150μm metal wires are provided. The voltage (MV) applied to the grid wire 13 is approximately the same voltage as the desired charging potential of the photoreceptor. The voltage (Hv) applied to the corona wire 12 is
Corona discharge starts around 4 kV, and it becomes possible to charge the photoreceptor 1. When the corona applied voltage (Hv) reaches about 7 to 9 kV, corona discharge becomes active and a large amount of corona ions are generated, and a light emission phenomenon is observed around the corona wire 12. However, even if a large amount of corona ions are generated, the controllability of the grid wire 13 allows the photoreceptor 1 to be charged to an arbitrary potential. When a charger that utilizes such a discharge state is used in the recharging process of a two-color recording device as shown in FIG. It plays the role of irradiating the entire surface, and charges to a predetermined potential while suppressing the rise in potential of the background area after the first development. As a result, there is no need to provide a special step of irradiating the entire surface as in the past, and uniform recharging can be obtained simply by setting a high corona applied voltage.

Next, a specific example of a two-color recording apparatus using the charger having the above-described structure will be described below with reference to FIG. Initial charger 2 using Se-Te drum as photoreceptor 1
Uniform charging of about 500V is performed. Next, negative exposure corresponding to color A is performed to form a latent image, and then first development, that is, reversal development using a two-component magnetic brush developer 4 using positive polarity toner is performed in red. The bias voltage applied to the developing device 4 is
The voltage should be 300-400V. As a result, a red first image is formed on the photoreceptor 1. At this time, the unsaturated potential ΔV due to the first development is about 200V. Next, a scorotron is used as the rebander 5 to apply approximately 7 to 9 KV to the corona wire and approximately 800 to 1000 V to the grid wire. A bluish light is generated around the corona wire, and this light charges the entire photoreceptor 1 to about 800V while suppressing the increase in the potential of the background area after the first development. As a result, the first
The unsaturated potential due to development can be suppressed to 50V or less. Next, negative exposure corresponding to B color is performed to form a latent image. Thereafter, a one-component magnetic toner developer 7 is used to perform reversal development of black magnetic toner. The bias voltage applied to the developing device 7 is
The voltage should be around 800V. Through the above steps, it is possible to form good two-color toner images of red and black on the photoreceptor.

The luminescence phenomenon in corona discharge is positive corona discharge,
Although this can be seen in both negative corona discharges, positive corona discharge results in a more uniform luminescence distribution, while negative corona discharge produces multiple bright spots on the corona wire and the luminescence distribution is non-uniform.

In this example, the case of positive corona discharge was described, but since the distance between the corona wire and the photoreceptor in the corona charger is about 10 to 20 mm, the light intensity distribution on the photoreceptor is uniform even in negative corona discharge, and the positive corona Almost the same effect as in the case of electric discharge can be obtained.

In this embodiment, a two-color recording apparatus has been described, but the present invention is to align the potential of the image area after the first development and the potential of the background area before the second exposure, and perform recharging. This method can also be implemented in a multicolor recording device that uses three or more colors.

Furthermore, in the present embodiment, the first developing device 4 is described as one that uses red two-component magnetic brush development, and the second developing device 7 is described as one that uses black one-component magnetic toner development. It is not limited by the color of the toner or the color of the toner.

(F) Effects of the invention As explained in detail above, according to the present invention,
Since recharging is carried out using a scorotron in a discharge area accompanied by a light emission phenomenon, uniform charging can be performed while eliminating the potential difference (unsaturated potential ΔV) between the image area and the background area. This has the effect that good multicolor recording without color mixing can be obtained with a simplified process.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a two-color recording device, and Figure 2 is a schematic diagram of a two-color recording device.
FIG. 3 is a diagram for explaining conventional recharging control, and FIG. 4 is a diagram of a scorotron, which is a recharging device used in the present invention. It is a schematic diagram. In the drawings, 1 is a photoreceptor which is an image forming medium;
5 is a recharger, 12 is a corona wire, 13 is a grid wire, and 14 is a metal case.

Claims (1)

[Scope of Claims] 1. an endless image bearing member; a plurality of image forming means arranged along the moving direction on the image bearing member and each forming an electrostatic latent image on the image bearing member; A plurality of developing means are provided corresponding to the image forming means and develop the electrostatic latent image formed on the image carrier using toners of different colors; and among the plurality of image forming means. and a recharging means for recharging the image bearing member immediately before the image forming means other than the image forming means at the frontmost stage with respect to the moving direction of the image bearing member, and the recharging means is a scorotron. A multicolor recording device characterized in that the scorotron performs recharging in a corona discharge region accompanied by light emission.