JPS59224866A - 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 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 for a specific time to vibrate a vibrator 14 of electrostrictive type bimorph material, etc., using piezoelectric effect continuously for the specific time. Consequently, a metallic thin wire 15 for discharge is extended and contracted lengthwise at specific intervals of time, 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 longitudinal ends of a shield 1 as a corona discharge device, and a corona discharge electrode is formed between the insulating blocks 2 and 3 with a heel diameter of 50 microns. A fine discharge metal wire 4 of approximately 100 microns is stretched, and a high voltage of AC or DC (±3KV) is applied.
A device in which corona discharge is caused by applying a voltage of ~±1 pulsation is known.

Since this corona discharge device is easy to produce, it is widely used in copying machines.

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

This is remarkable when a negative (-) polarity voltage is applied to the thin discharge metal strip 1.

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 discharge metal fine fibers becomes dirty due to toner particles adhering to the inside of the machine, corona discharge in that area is inhibited.
Release 1'! This is thought to be due to variations in the oxidation state of the metal surface of the thin metal wire for use, resulting in variations in the number of work gates, and thus the secondary electrons emitted from the surface are non-uniform.

Therefore, in order to solve the above-mentioned problem, conventionally, the number of secondary electrons is increased by heating the discharge metal #I wire with electricity, or a scorotron structure is provided with a grid electrode.

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

OBJECTS OF THE INVENTION It is an object of the invention to prevent non-uniform distribution of discharge current along the length of a corona discharge electrode with low power consumption.

Composition of the invention A device equipped with a device that applies mechanical strain to the corona discharge electrode.

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

Insulating blocks II, +
The t@R block 11 is provided with a high voltage terminal 13, the insulating block 12 is provided with a vibrator 14, and a corona discharge electrode is provided between the insulating block 11 and the vibrator 14. A fine discharge metal wire I5 is stretched, the high voltage terminal 13 is connected to a high voltage power source, and the vibrator 14 is given vibration by an oscillator 16.

The vibrator 14 is an electrostrictive bimorph using a piezo effect, and the frequency may be any value in the range of about 100 H'Z to 10 KFIz.

The operation is controlled by the oscillator 16 control mechanism 17, and the signal R1 (
That is, when the copy start signal) is input, the oscillator 16 is driven for a predetermined period of time, and the vibrator 14 is vibrated for a predetermined period of time.

Due to the breakage, the fine discharge metal wire I5 is expanded and contracted in the length direction at predetermined time intervals.

When the thin metal wire 15 for discharge is expanded and contracted in this way, strain in the length direction is repeatedly generated between the metal crystal lattices of the thin metal wire 15 for discharge at a fast cycle.

In other words, expansion and contraction distortion occurs.

For this reason, electrons are emitted from the surface of the discharge metal thin wire 150 due to the exoelectron emission phenomenon, and the secondary electron action necessary for corona discharge is supplemented by the emitted electrons.
, the corona discharge current density increases.

Due to the breakage, the density distribution of ions generated from the vicinity of the thin metal wire 15 for discharge metal is made uniform in the length direction.
The distribution of the free 'FA' f4 flow is quite uniform along the length.

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.

Therefore, in order to stably emit electrons by the exoelectron emission phenomenon, it is necessary to give elongation at a constant and fast cycle, and in the present invention, the oscillator 16 is used to give the fine discharge metal wire 15 a constant cycle. I tried to give it a stretching 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.

Furthermore, when the discharge current density distribution was measured in a state where no expansion/contraction N@ was applied, it was found that the distribution was non-uniform as shown in FIG.

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

As shown in Fig. 5, even when a sawtooth electrode +5' is used as a corona discharge electrode, expansion and contraction strain is generated by applying vibration at a constant period in the length direction of the sawtooth electrode. By doing so, it is possible to increase the corona discharge current generated from the sawtooth tip 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 the discharging metal wire 15 is stretched between the insulating bronzes 211 and 12 on both sides. , a motor 2o that rotates in forward and reverse directions on the other side insulating block 12
The rotating shaft 21' of the two is connected. The other insulating block 12 is a stepped cylinder, and is rotatably inserted into the stepped hole 121α of the auxiliary insulating block 121.

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

As a result, the fine discharge metal wire 15 is repeatedly rotated forward and backward, giving it a twisting motion, and radial strain is repeatedly generated between the metal crystal lattices at an annual cycle. Twisting and torsional distortion occur.

As a result, electrons are emitted due to the exoelectron emission phenomenon in the same way as in the case where expansion/contraction strain occurs, so that the discharge current distribution along the long direction of the discharge metal thin i (I l 5) 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 rotation speed exceeds 10@, the thin metal wire for discharge breaks.

In summary, by applying mechanical strain such as expansion/contraction strain or torsional strain to the corona discharge electrode uniformly over its entire length and at regular, rapid cycles at predetermined time intervals, electrons can be generated by the exoelectron emission phenomenon. By emitting , the secondary electron action necessary for discharge may be supplemented.

This equalizes the density distribution of ions generated from the vicinity of the corona discharge electrode, so that the distribution of discharge current in the length direction becomes extremely uniform.

Effects of the Invention Electrons are emitted from the corona discharge electrode 15 by an exoelectron emission phenomenon, thereby supplementing the secondary electron action necessary for discharge, so that the distribution of discharge current becomes non-uniform in the length direction. f that can be prevented and also drive an oscillator, etc.
Since it requires only a little less than 2 liters of power, the power consumption is low and it is advantageous in terms of cost.

[Brief explanation of drawings]

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 the front page 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 is a longitudinal cross-sectional view when a sawtooth discharge electrode is used.
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 Soeki Figure 1 Figure 2 Figure 5 Figure 5 I Dera I, Commercial.

Claims (1)

[Claims] In a corona discharge device in which a voltage is applied to a copper discharge electrode I5 stretched within a shield 10 to cause a corona discharge, a device for applying mechanical strain to the corona discharge electric plate 15 is provided. Characteristic corona discharge device.