JPS59224865A - Corona discharger - Google Patents

Abstract

PURPOSE:To prevent the distribution of a discharge current which flows in the lengthwise direction of an electrode from becoming uneven with small power consumption by providing a device which applies repetitive mechanical strain to the electrode continuously. CONSTITUTION:The operation of an oscillator 16 is controlled by a control mechanism 17, and when a signal R1 is inputted with a copy button 18 turned on, the oscillator 16 is driven until the completion of copying operation to vibrate a vibrator 14 continuously during the copying operation. Consequently, a metallic thin wire 15 for discharge is extended and contracted lengthwise continuously during the copying operation, so lengthwise strain is generated among metallic crystal lattices repeatedly at a short period. Therefore, electrons are emitted from the surface of the metallic thin wire 15 through an exo-electron emission phenomenon and secondary electron operation necessary for corona discharge is supplemented to increase corona discharge current density. Thus, the density distribution of ions generated near the metallic thin wire 15 is uniformed lengthwise, so the distribution of the discharge current is extremely uniform in the lengthwise direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a corona discharge device used as a device for charging a photoreceptor of a copying machine.

Conventionally, as shown in FIG. 1, insulating blocks 2 and 3 are provided at both ends of a shield 1 in the longitudinal direction of a four-wheel discharge device, and a wire with a diameter of A fine discharge metal wire 4 of approximately 50 microns to 100 microns is stretched, and a high voltage of AC or DC (±3KV) is applied.
~±l OAT') is known to cause corona discharge.

This corona discharge device has a simple configuration and is therefore widely used in copying machines.

However, on the other hand, if the thin metal wire for discharge becomes dirty, the uniformity of the distribution of radiation and current along the length of the thin metal wire for discharge will be impaired (in other words, the discharge current will become non-uniform). It has its drawbacks.

This is remarkable when a negative (-) voltage is applied to the thin metal wire for discharge.

As mentioned above, if the uniformity of the discharge current is impaired, for example, when used as a charging device for a photoreceptor, the uniformity of the charging potential of the photoreceptor will be impaired, resulting in significant density shading in the copied image. This results in a decrease in image quality.

The reason why the uniformity of the discharge current is impaired is that when the surface of the fine metal wire for discharge becomes dirty due to toner particles adhering to it inside the copying machine, corona discharge in that area is inhibited.
Because there are variations in the oxidation state of the metal surface of the thin metal wire for discharge and variations in the work function, 2 is released from the surface.
This is thought to be due to the non-uniformity of secondary electrons.

Therefore, in order to solve the above-mentioned problems, conventional methods have been to increase the number of secondary electrons by heating thin discharge metal wires or to make scorotron barrels with grid electrodes.

However, either method consumes a lot of power and requires an expensive power source, resulting in problems such as increased costs.

OBJECT OF THE INVENTION It is an object of the invention to prevent uneven distribution of discharge current along the length direction of a corona discharge electrode with low single force consumption.

Structure of the Invention A device is provided that continuously applies repetitive mechanical strain to a corona discharge electrode.

Example The present invention will be described in detail below with reference to FIG. 2 and subsequent figures.

Insulating blocks I+, + are provided at both longitudinal ends of the shield 10.
The insulating block 11 is provided with a high voltage terminal 13, and the insulating block 12 is provided with a vibrator 14.
A thin discharge metal wire 15 serving as a corona discharge electrode is stretched between the vibrator 14 and the vibrator 14, and the high-voltage terminal 13 is connected to a high-voltage power source.

The vibrator 14 is an electrostrictive bimorph using a piezo effect, and the frequency may be any value in the range of about 100H2 to 100A''#z.

The operation of the oscillator 16 is controlled by a control mechanism 17, and the control mechanism 17 receives a signal R1 (
That is, when the copying start signal) is input, the oscillator 16 is driven until the copying operation is completed, and the vibrator 14 is caused to vibrate continuously according to the amount of copying operation.

As a result, the thin metal wire 15 for discharge is expanded and contracted in the length direction continuously with the amount of copying operation.

In this way, the thin metal wire 15 for discharge is expanded and contracted. (2) When the discharge metal wire is moved, distortion in the length direction occurs repeatedly at a fast cycle.

In other words, expansion and contraction distortion occurs.

For this reason, electrons are emitted from the surface of the fine discharge metal wire 15 due to the exoelectron emission phenomenon, and the emitted electrons supplement the secondary electron action necessary for corona discharge.
Corona release! Current density increases.

As a result, the density distribution of ions generated from the vicinity of the fine discharge metal wire 15 is made uniform in the length direction, so that the distribution of the discharge current becomes extremely uniform along the length direction.

Figure 3 shows the detected count of the number of electrons emitted from the surface of a thin metal wire when it is stretched at a constant speed.When stretching is applied, the number of emitted electrons increases rapidly and sequentially. However, it can be seen that when the elongation is stopped, the number of emitted electrons gradually decreases in a relatively short period of time, and when elongation is applied again, the number of emitted electrons increases again as described above.

From this, in order to stably emit electrons due to the exoelectron emission phenomenon, it is necessary to constantly apply elongation at a fast cycle, and in the present invention, the oscillator 16 performs a copying operation on the discharge metal a-line 15. The amount (that is, during discharge) is given continuous expansion and contraction motion.

Next, when a voltage of minus (-) 5 g was applied to the thin metal wire 15 for discharge, and the same stretching motion as described above was applied, the discharge current density distribution was measured, as shown in Fig. 4 (a). The distribution was extremely uniform.

In addition, when the discharge current density distribution was measured in a state where no stretching motion was applied, the distribution was non-uniform as shown in FIG.

From this, it is clear that by applying stretching motion (that is, periodic vibration in the length direction) to the thin metal wire 15 for discharge, it is possible to prevent the distribution of the discharge current from becoming uneven in the length direction. .

As shown in Fig. 5, even when a sawtooth electrode [15'] is used as a corona discharge electrode, it can be expanded and contracted by applying a constant period of vibration in the longitudinal direction of the sawtooth shape and crosspiece. By generating strain, it is possible to increase the corona discharge current generated from the tip of the sawtooth and make the discharge current distribution in the length direction uniform.

FIG. 6 is a perspective view of the second embodiment, in which the other side insulating block 12 is rotatably supported on the shield 10, and a thin metal wire 15 for discharging is stretched between the two insulating blocks +1.12. Motor 20 that rotates in forward and reverse directions on the other side insulating block 12
The rotating shaft 21' of the two is connected. In other words, the other insulating block 12 is a stepped cylinder, and is rotatably inserted into the stepped hole 12+α of the auxiliary insulating block 12'.

The operation of the motor 20 is controlled by the control mechanism 21, and the control mechanism 21 controls the motor 20 simultaneously with the voltage application (that is, at the same time as the discharge) using a signal from the means 22 for applying voltage to the high voltage terminal 13. Tighten and rotate forward and reverse.

As a result, 15 fine discharge metal wires are repeatedly rotated forward and reverse to impart twisting motion, and radial strain is repeatedly generated between the metal crystal lattices at a fast cycle. In other words, torsional strain occurs.

As a result, electrons are emitted by the exoelectron emission phenomenon in the same way as when expansion/contraction strain occurs, so that the discharge current distribution along the length of the fine discharge metal wire 15 becomes uniform as described above.

Note that the above-mentioned twisting motion is, for example, 5 rotations clockwise,
Next, it is necessary to repeatedly reverse the direction of rotation by rotating it counterclockwise 10 times to apply it to the thin metal wire 15 for discharge, and the rotation speed and number of rotations are determined by the thickness and length of the thin metal wire 15 for discharge. However, in the case of a corona discharge device used in a copying machine, it has been found that when the number of revolutions exceeds 10 times, the thin metal wire for discharge breaks.

To summarize the above, the exoelectron emission phenomenon can be achieved by applying mechanical strain such as expansion/contraction strain or torsional strain uniformly over the entire length of the electrode for corona emission ↑e in a steady and repeated manner at a rapid cycle. By emitting electrons, the secondary electron action necessary for discharge may be supplemented.

As a result, the density distribution of ions generated from the vicinity of the corona discharge electrode is made uniform, so that the distribution of the emitted Ti'Fl flow in the length direction becomes uniform.

When used as a photoreceptor charging device in a copying machine, the repetition frequency of mechanical strain is related to the overall speed of the copying process, and if the repetition frequency is too low relative to the copying speed, the density of emitted electrons will be reduced The density and power of charging are undesirable as they cause the density of the copied image to be too dark, but the copying speed is 1Qcm/? #C is about 50
? (If the value is 74ac or more, the image quality of multiple images will not be adversely affected.

Effects of the Invention Electrons are emitted from the corona discharge wire 15 by the exoelectron emission phenomenon, thereby replenishing the secondary electron action necessary for discharge, so that the distribution of discharge current becomes non-uniform in the length direction. This can be prevented, and since only a weak amount of power is required to drive an oscillator, power consumption is low, and it is advantageous in terms of cost.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a conventional example, Fig. 2 is a longitudinal sectional view showing an embodiment of the present invention, and Fig. 3 shows the relationship between the amount of elongation and the number of emitted electrons when elongation is given to a thin metal wire for discharge. Figure 4 is a table showing the discharge current density distribution with and without elongation, Figure 5 is a longitudinal cross-sectional view when a sawtooth discharge electrode is used, and Figure 6
The figure is a perspective view of the second embodiment. 10 is a shield, and 15 is a corona discharge electrode. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Masaaki Yonehara Patent Attorney Tadashi Flood Figure 1 Figure 2 Figure 5 Fuyukiyo 1. Ike Figure 3 Time-

Claims (1)

[Claims] In a corona discharge device in which a voltage is applied to a corona discharge mW 15 stretched in a shield 10 to cause corona discharge, a device is provided that continuously applies repetitive mechanical strain to the corona discharge electrode 15. A corona discharge device characterized in that: