JPS6395474A - Discharge device - Google Patents

Abstract

PURPOSE:To obtain an electrostatically charged width corresponding to a copying size while the electrified potential is maintained at a fixed level, by providing a switching means which can selectively connect control electrodes divided into plural parts to either an earth or earthed constant-voltage element. CONSTITUTION:Control electrodes 6 which are divided into plural parts corresponding to copying sizes are provided between a discharge element 1 and body 5 to be charged electrostatically and switching means which can selectively connect the divided control electrodes 6 to either specific potential terminals including earths or earthed constant-voltage elements if necessary. When, for example, the copying size has a width (l), switches 15a and 15b are connected to B side and the remaining switches 16a and 16b are connected to A side. Then the control electrode 6 corresponding to the required copying width (l) is connected to constant-voltage elements 18a and 18b and a part of the control electrodes connected to the switches 15a and 15b are earthed. Since electrification of a width corresponding to the copying size is obtained, therefore, no erase lamp is required and, the cost can be reduced.

Description

[Detailed description of the invention] (Technical field) It relates to charge removal devices for electrostatic recording, electrophotography, etc.

The present invention relates to a discharge device having a discharge element comprising an internal electrode covered with a dielectric and a discharge electrode disposed opposite to the internal electrode with the dielectric interposed therebetween. This type of discharge device can be used as a charge removal device for electrostatic recording, electrophotography, etc., and can also be applied to various fields as a discharger and an ion source.

(Prior Art) Conventionally, in an electrophotographic mount, a discharge device such as a corona charger charges the entire surface of a charged object such as a photoreceptor.
Because of the developing structure, in order to obtain copies of each copy size, it was necessary to dispose an erase lamp between the charger and the developing device to expose and eliminate unnecessary portions.

Therefore, an internal electrode covered with a dielectric material and a radiation 1! A technique has been proposed that attempts to solve this problem by using a discharge device composed of electrodes.

According to Japanese Unexamined Patent Publication No. 58-48073, the necessary N7F1 width can be obtained by dividing the internal electrode into a plurality of parts and applying a voltage to each electrode according to the paper size.

According to Japanese Patent Application Laid-Open No. 60-181763, a similar effect can be obtained by providing a plurality of the discharge electrodes and selectively applying a voltage to the discharge electrodes according to a desired charging width.

However, these techniques also have drawbacks.

That is, if the number of electrodes to which a voltage is applied or the length of the electrodes changes, the load capacitance with respect to 1 changes, and the intensity of discharge changes, so that a constant potential cannot be obtained for band 1.

In order to solve this problem, the output of the power supply must be made variable according to changes in the load capacity, but this not only increases costs but also requires high AC or DC voltage to be applied to the switching means, such as switches. Therefore, sufficient withstand voltage is required.

(Purpose) The present invention was made based on this background,
It is an object of the present invention to provide a control electrode between a discharge device and a charged belt, thereby making it possible to vary the charging width depending on the copy size.

(Structure) That is, the present invention provides a switching means that can selectively connect a plurality of divided control electrodes to either the ground or the grounded constant voltage element, thereby maintaining a constant charging potential. , it is an object of the present invention to provide a discharge device that can obtain a charging width that corresponds to the copy size.

A detailed description will be given below based on the drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

The discharge element 1 is composed of an internal electrode 2 covered with a dielectric 4 and a discharge electrode 3 provided facing the outer surface of the dielectric 4, and is arranged facing a charged object 5 such as a photoreceptor. will be established. An AC voltage is applied between the internal electrode 2 and the discharge electrode 3 by a power source 10. This AC voltage is obtained by boosting the output from the low voltage drive circuit 11 with a step-up transformer 12. Furthermore, a DC electric field is formed between the discharge element 1 and the charged object 5 by the voltage doubler rectifier circuit 13 .

Further, a charging current detection circuit 14 composed of a resistor and a capacitor is connected between the part indicated by point P of the voltage doubler rectifier circuit 13 and the back electrode of the charged object 5, and the output of this detection circuit 14 is a low voltage. By being fed back to the drive circuit 11, the power supply 1o is controlled to have a constant current.

In the discharge device configured as described above, a control electrode 6 divided according to the copy size is arranged between the discharge element 1 and the charged object 5, and the divided control electrode 6 is connected to the ground as necessary. A switching means is provided to enable selective connection to either a specific potential terminal (including zero potential) or a grounded constant voltage element.

Therefore, for example, if the copy size is the width indicated by l in the figure, by connecting switch 15a and switch 15b to the B side, and connecting the remaining switches 16a and 16b to the A side, the width required for copying can be adjusted. The control electrode 6 corresponding to Vl is connected to constant voltage elements (ZNR) 18a and 18b, and the control electrode 6 corresponding to Vl is connected to the switches 153 and 15b. The 1B electrode is grounded.

Therefore, the portion of the charged body 5 corresponding to the grounded control electrode 6 is not charged because the charging current flows to the control electrode 6, and as a result, the charged body 5 is! It is charged to a potential determined by ZNR with a width indicated by . Therefore, charging of unnecessary non-image areas can be prevented. In the figure, the B side terminal of the switch is connected to the ground (zero potential), but by connecting it to a potential terminal with a polarity opposite to that of the charging polarity, charging of the charged object can be completely prevented.

Note that 17a, 17b, and 19 are also constant voltage elements.

FIG. 2 shows various shapes of the control electrode 6.
fa) is a slit shape, (bl is a mesh shape, and (C) is a honeycomb shape.

In addition, these figures show the case where the original is centered, and the control electrode 6 is divided at both ends. However, when the original is one-sided, one end of the control electrode 60 is divided according to the copy size. Just split it up.

Although only three types of shapes are shown here, the shape of the control is not limited to these, and any shape may be used as long as it fulfills the desired function.

FIG. 3 shows examples in which discharge elements 1 of various shapes are used.

As described above, the control 1i pole divided according to the copy size is arranged between the discharge element and the charged object, and the specific potential terminal including the ground (zero potential) and the grounded constant voltage element are connected to each other. By providing a switching means that can selectively connect the divided control electrodes, a charging width corresponding to the size of the copy can be obtained, which eliminates the need for an erase lamp that was previously required, resulting in cost reduction. It can be measured.

Also, system '4B 1! By connecting a constant voltage element (Zener diode) to the grid, an effect similar to that of a grid conventionally used in a scorotron or the like can be obtained, and the charging potential can be controlled.

Furthermore, since the load capacity of the discharge element itself is constant, there is no need to vary the output of the power supply.

(Effects) As described above, according to the present invention, (1) an electrification width corresponding to the copy size can be obtained, so an erase lamp is not necessary.

(2) There is no need to make the power output variable.

(3) By connecting a constant voltage element (Zener diode) to the control electrode, a grid effect can be obtained and the charging potential can be controlled.

(4) Since no voltage drop is applied to the limiting electrode a, there is no need to consider withstand voltage.

It has the following effects.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of a discharge device showing one embodiment of the present invention, Fig. 2 (+!l), (b), (C1, a diagram showing various shapes of control electrodes, Fig. 3) (a), (b),
(C1, (d+ is a simplified diagram showing an example in which discharge elements of different shapes are used. 2... Internal electrode, 3... Discharge electrode, 4... Dielectric, 5...・Charged object, 6... Control electrode, 10... AC applying means, 13... DC electric field applying means. Fig. 2'22

Claims (2)

[Claims] (1) A discharge element consisting of an internal electrode covered with a dielectric and a discharge electrode disposed opposite to the internal electrode via the dielectric, and means for applying an alternating current voltage between the two electrodes. a means for applying a DC voltage between the discharge element and the charged object; a means for forming a DC electric field between the discharge element and the charged object; and a plurality of means arranged between the discharge element and the charged object. A discharge device characterized in that it has a control electrode divided into two. (2) At least one of the plurality of control electrodes is provided with a switching means so that it can be selectively connected to either a specific potential terminal including ground (zero potential) or a grounded constant voltage element. A discharge device according to claim (1).