JPH0463370A - Scorotron electrifier - Google Patents

Abstract

PURPOSE:To allow the sufficient electrification of a photosensitive body is a short period of time and to decrease the amt. of the ozone to be generated by setting the potential difference between a discharge wire and a shield smaller than the potential difference between the discharge wire and a grid. CONSTITUTION:This electrifier is constituted of the discharge wire 1, the shielding electrode 3 and the grid electrode 3. A high-voltage power source 4 is connected to the discharge wire 1, a varistor 5a to the shielding electrode 3 and a varistor 5b to the grid electrode 3, respectively. The potential difference between the discharge wire 1 and the shield 2 is set smaller than the potential difference between the discharge wire 1 and the grid 3. The ratio of the quantity of the charge flowing from the conventional Scorotron electrifier to the shield is, therefore, decreased and the photosensitive body is sufficiently electrified even if the current quantity to be applied to the discharge wire is small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a scorotron charger, and more particularly to a scorotron charger used in electrophotographic image forming apparatuses such as copying machines and printers.

[Conventional technology]

As shown in Fig. 2, a conventional scorotron charger consists of a discharge wire 1, a shield 2, and a grid 3. A high-voltage power supply 4 is connected between the discharge wire 1 and the ground, and a varistor resistor or the like is connected between the grid 3 and the ground. A grid potential control means 5 is provided, and the shield 2 is directly connected to ground or connected to a third
As shown in the figure, it was normal to have the same potential as grid 3.

[Problem to be solved by the invention]

In the conventional scorotron charger described above, the potential difference between the discharge wire potential and the grid potential is equal to or less than the potential difference between the discharge wire potential and the shield potential. Normally, the amount of charge emitted from the discharge wire is the sum of the amount that contributes to the charge on the photoreceptor, the amount that flows into the grid, and the amount that flows into the shield. The ratio of the amount of charge flowing into the shield is large. Therefore, in processes such as high-speed printers that require a sufficient amount of charge to be applied to the photoreceptor in a short period of time, it may not be possible to obtain sufficient charge, or it may be necessary to apply a large current to the discharge wire in order to obtain sufficient charge. This has the disadvantage of increasing the amount of ozone generated.

[Means to solve the problem]

The scorotron charger of the present invention is configured such that the potential difference between the discharge wire and the shield is smaller than the potential difference between the discharge wire and the grid in the scorotron charger that charges the photoreceptor of an electrophotographic image forming apparatus.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing a cross section of an embodiment of the present invention.6 This embodiment is composed of a discharge wire 1, a shield electrode 2, and a grid electrode 3. But, shield electric! A varistor 5a is connected to the grid electric wire fi3, and a varistor 5b is connected to the grid electric fi3. In the case of a negative charging type scorotron charger, the output voltage of the varistor 5a is ○V>grid potential>shield potential>
The discharge wire potential becomes the discharge wire potential, and in the case of a positively charged scorotron, the discharge wire potential>shield potential>grid potential>○V
It is determined that

Therefore, the potential difference between the discharge wire 1 and the shield 2 is smaller than the potential difference between the discharge wire 1 and the grid 3, and the proportion of charge flowing into the shield is higher than that of the conventional scorotron charger shown in FIGS. 2 and 3. becomes smaller,
Even if the amount of current applied to the discharge wire is small, it is possible to sufficiently charge the photoreceptor.

〔Effect of the invention〕

As explained above, the present invention connects a voltage generating means to the shield electrode, and (potential difference between the discharge wire and the grid)
(potential difference between the discharge wire and the shield), it is possible to sufficiently charge the photoreceptor in a short time, and by reducing the amount of charge applied to the discharge wire, the amount of ozone generated can be reduced. There is an effect.

In this embodiment, a varistor is used as the voltage generating means, but the same effect can be obtained by using a high resistance body or a constant voltage power supply.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a cross section of one embodiment of the present invention, and FIG.
Figures 1 to 3 are explanatory diagrams showing a cross section of a scorotron charger according to the prior art. DESCRIPTION OF SYMBOLS 1... Discharge wire, 2... Shield, 3... Grid, 4... High voltage power supply, 5a, 5b, Revaristor. Diagram

Claims (1)

[Claims] 1. A scorotron charger for charging a photoreceptor of an electrophotographic image forming apparatus, characterized in that the potential difference between the discharge wire and the shield is smaller than the potential difference between the discharge wire and the grid. Scorotron charger. 2. A high-voltage power supply that supplies power to the discharge wire, a first element connected to the shield and having a voltage drop between the terminals smaller than the output voltage of the high-voltage power supply, and a first element connected to the grid and connected between the terminals. 2. The scorotron charger according to claim 1, further comprising a second element whose voltage drop is smaller than a voltage drop between terminals of said first element. 3. The scorotron charger according to claim 2, wherein a varistor is used for the first and second elements.