JPH0561629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a corona discharge device that applies electric charge by corona discharge.

Prior Art Generally, in a corona discharge device, a large amount of ozone is generated during discharge. It is known that this ozone not only deteriorates the photoreceptor of a copying machine, but also is harmful to the human body. For this reason, in Japanese Patent Application Laid-Open No. 56-154759, as shown in FIGS. 1 to 4, a heat generating member 5,
A corona discharge device has been proposed in which a plurality of heat generating members 5, 6, 8 are installed in tension, and the ozone generated in the vicinity of the corona electrode 1 is thermally decomposed by the heat generating members 5, 6, 8.

However, in the above device, the heat generating member 5,
6 and 8, the heat generation temperature is 200 DEG C. to 300 DEG C., so the corona electrode 1 expands due to the heat, resulting in non-uniform discharge characteristics. Furthermore, when the above-mentioned apparatus is used in an electrophotographic copying machine, the heat generated by the heat-generating members 5, 6, and 8 causes deterioration of the photoreceptor and fusion of toner, and further disadvantages arise in that power consumption increases.

In order to explain many of the above problems, the heat generating member 5,
It is possible to suppress the amount of heat generated by 6.8. However, when the heat generation temperature is lowered, part of the ozone generated near the corona electrode 1 is transferred to the heat generation member 5,
Although some ozone is thermally decomposed by the ozone decomposition members 5, 6, and 8, some of them pass between the heat generating members 5, 6, and 8 without being decomposed, resulting in low ozone decomposition efficiency.

Purpose The present invention has been made in view of the above points, and its purpose is to efficiently decompose generated ozone and to prevent deterioration of the photoreceptor, toner fusion, increase in electric power, etc. There is no corona discharge device provided.

Summary In order to achieve the above object, a corona discharge device according to the present invention includes a counter electrode formed of a metal plate,
A heat-resistant insulating member that covers the surface of the counter electrode, a thin wire-shaped excitation electrode fixed to the surface of the counter electrode so as to face the counter electrode via the heat-resistant insulating member, and creeping discharge generated near the excitation electrode. A power supply that applies high-voltage alternating current between the counter electrode and the excitation electrode in order to The gist is that the device is equipped with an electrode.

Embodiment FIG. 5 shows an embodiment of the present invention, in which 10 is a main body of a corona discharge device, in which a counter electrode 11a made of metal such as copper is covered with a heat-resistant insulating member 11b made of ceramic, glass, polyimide resin, etc. At the same time, a charging panel 11 having a thin wire-shaped excitation electrode 11c fixed on its outer surface, a mesh-shaped control electrode 12 provided adjacent to the charging panel 11, and a U-shaped insulating member is used to charge the charging panel 11. Support member 13 that covers three sides of panel 11 and supports control electrode 12
, a high voltage AC power supply 14 connected between the counter electrode 11a and the excitation electrode 11c, and a first DC power supply 1 connected between the excitation electrode 11c and the control electrode 12.
5, and a second DC power supply 18 connected between the control electrode 12 and the back electrode 17 of the charged object 16.

In the above configuration, when a high voltage AC voltage is applied between the counter electrode 11a and the excitation electrode 11c by the high voltage AC power supply 14, a corona discharge (creeping discharge) occurs near the excitation electrode 11c, and positive and negative Ions are generated. These ions can charge the charging object 16 to arbitrary polarity and potential depending on the polarity of bias applied by the first DC power supply 15 and the second DC power supply 18. For example, when charging the charging object 16 to a positive polarity, as shown in the figure, the positive electrode of the first DC power supply 15 is connected to the excitation electrode 11.
c. Connect the negative electrode to the control electrode 12, connect the positive electrode of the second DC power supply 18 to the control electrode 12, and connect the negative electrode to the back electrode 11.
a, an electric field is formed from the excitation electrode 11c toward the charged object 16, and the excitation electrode 1
Of the positive and negative ions generated in the vicinity of 1c, only positive ions are accelerated in the direction of the charging object 16 to impart a charge. Note that the charged object 16 is charged to approximately the same potential as the control electrode 12.

Incidentally, the creeping discharge that occurs in the charging panel 11 is accompanied by considerable heat generation. The corona discharge device has a function of decomposing ozone generated during creeping discharge by skillfully utilizing its heat generation.

Specifically, the control electrode 12 adjacent to the charging panel 11 is heated by the heat generated by the creeping discharge, and thermally decomposes ozone in the space A surrounded by the control electrode 12, the charging panel 11, and the support member 13. .

Furthermore, by forming the support member 13 that surrounds the corona discharge device on three sides from a material with good heat insulation properties such as acrylic, it is possible to efficiently heat the space A without letting the heat generated by the creeping discharge escape to the outside. can. In order to heat the space A to a temperature sufficient for ozone decomposition, the thickness d ₁ of the support member 13 must be approximately 5 mm, and the gap between the charging panel 11 and the control electrode 12 must be approximately 1 mm.
It is preferable to set it to about 5 mm.

Using the above corona discharge device 10, the output of the high voltage AC power supply 14 is 7.5KVrms and 10KHz, the output of the first DC power supply 15 is 5KV, and the output of the second DC power supply 18 is
When the voltage was 9 KV, the width d ₁ of the support member 13 was 2 mm, and the gap d ₂ between the charging panel 11 and the control electrode 12 was 3 mm, the temperature of the charging panel 11 rose to 62°C and the temperature of the control electrode 12 rose to 50°C. Was. At this time, the ozone concentration outside the control electrode 12 was measured and found to be 0.2 ppm. When the ozone concentration was measured under the same conditions except that the control electrode was removed, it was 2 to 3 ppm.

As is clear from the above experiment, the amount of ozone generated by the corona discharge device 10 could be reduced to 1/10 or less compared to one without the control electrode 12. this is,
It was also confirmed that the results were almost the same as when ozone was removed using an ozone filter. In addition, control electrode 1 with an ozone concentration of 0.2 ppm and 50 °C
It was also confirmed that the temperature at 2 temperatures had virtually no adverse effect on the photoreceptor.

FIG. 6 shows a second embodiment, in which the control electrode 12 is formed of an electric heating member such as nichrome, and a heater power source 19 is provided, but the other configuration is the same as that in FIG. 5.

The heater power source 19 is turned on for a certain period of time from the start of creeping discharge to heat the control electrode 12. That is, it is used to supplementally heat the control electrode 12 during the rise time until the control electrode 12 is sufficiently heated by the heat generated by the creeping discharge, and the ozone generated at the rise of the creeping discharge can also be efficiently decomposed. can.

FIG. 7 shows a third embodiment in which the corona discharge device 10 according to the present invention is applied to a static elimination charger that performs AC corona discharge, and the first DC power supply 15 in the embodiment of FIG. The power supply 20 and the second DC power supply 18 are replaced by a second AC power supply 21.

In the above configuration, the alternating electric field between the excitation electrode 11c and the control electrode 12 formed by the second AC power supply 20 is applied to positive and negative ions generated due to creeping discharge occurring near the excitation electrode 11c. Therefore, it is periodically accelerated in the direction of the control electrode 12, and is further periodically accelerated in the direction of the charged object 16 by the alternating electric field between the control electrode 12 and the back electrode 17 formed by the third AC power source 21. is accelerated to In this way, positive and negative ions are applied onto the charged object 16 to eliminate the charge on the charged object 16.

Specifically, the output of the second AC power supply 20 is 3~
10KVrms 40-5000Hz, preferably 7KVrms,
400Hz, and the output of the third AC electrode 21 is 3
~10KVrms, preferably 5KVrms at 40-5000Hz,
It is 400Hz.

FIG. 8 shows a modification of the third embodiment, in which the third AC power source 21 is removed, and the control electrode 12 and back electrode 1 are removed.
7 at the same potential.

In the above configuration, the control electrode 12 and the back electrode 17
Since they are at the same potential, when there is no charge on the charged object 16, the control electrode 12 and the charged object 16
No electric field is formed therebetween, and therefore the positive and negative ions generated by the creeping discharge are not supplied to the object to be charged.

However, if the charged object 16 has some charge even partially, an electric field is formed between the charged object 16 and the control electrode 12, and the positive or Negative ions are charged object 1
6 is given.

For example, when the charged object 16 is positively charged as shown in the figure, an electric field is formed from the charged object 16 toward the control electrode 12, and of the positive and negative ions generated by the creeping discharge, only the negative ions are A charge is applied to the charged object 16 by the action of this electric field. When the charges on the charged object 16 are neutralized by this charge application, the electric field between the charged object 16 and the control electrode 12 disappears, and the charge application also stops. In this way, the charge on the charged object 16 is removed.

In the third embodiment and its modifications, it goes without saying that ozone is decomposed by the action of heat generated by creeping discharge in the same way as in the first embodiment.

Effects As is clear from the above explanation, the corona discharge device according to the present invention decomposes ozone by efficiently utilizing the heat generated by creeping discharge, and therefore consumes no power for ozone decomposition. Not, also,
Since the heat generation temperature is also low, it does not cause deterioration of the photoreceptor or fusion of toner. Furthermore, by using the control electrode as a heating element and heating it only at the start of the creeping discharge, ozone decomposition at the start of the discharge can be efficiently performed without consuming a large amount of power.

[Brief explanation of the drawing]

1 to 4 are diagrams showing the conventional technology of a corona discharge device having an ozone decomposition function, FIG. 5 is a sectional view of the corona discharge device according to the present invention, and FIG.
FIG. 7 is a sectional view showing the third embodiment, and FIG. 8 is a diagram showing a modification of the third embodiment. 10... Corona discharge device main body, 11a... Counter electrode, 11b... Heat resistant insulating member, 11c... Excitation electrode, 12... Control electrode, 13... Support member,
14... High voltage AC power supply, 19... Power supply for heater.

Claims (1)

[Claims] 1. A counter electrode formed of a metal plate, a heat-resistant insulating member covering the surface of the counter electrode, and a heat-resistant insulating member fixed to the surface of the counter electrode so as to face the counter electrode through the heat-resistant insulating member. A thin wire-shaped excitation electrode, a power supply that applies high-voltage alternating current between the counter electrode and the excitation electrode in order to generate a creeping discharge near the excitation electrode, and a power source that faces the excitation electrode with a small distance between them and A corona discharge device characterized by comprising a mesh-shaped control electrode heated by heat generated during discharge. 2. The corona discharge device according to claim 1, wherein the control electrode is supported by an insulating and heat-insulating member. 3. The corona discharge device according to claim 2, wherein the insulating and heat-insulating member covers three directions other than the direction in which the excitation electrode of the corona discharge device is provided in a U-shape. 4. The corona discharge device according to claim 1, wherein the control electrode includes a heat generating means and generates heat for a certain period of time upon the start of corona discharge.