JP2001257054A - Electrification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost electrification device which has little generation of nitrogen oxide or ozone and can make a stable discharge without heating means. SOLUTION: An electrification device comprises a substrate 1 made of an insulation material, a plurality of excitation electrodes 2 formed on the surface of substrate 1, a dielectric layer 3 covering the surface of the substrate 2 formed with the excitation electrode 2, a discharge electrode 4 which is formed on the dielectric layer and has an opening portion 5 at the corresponding position of the excitation electrode 2, and by impressing a prescribed driving voltage between the excitation electrode 2 and the discharge electrode 4, discharging is made and the charged body 7 is electrically charged by the charged particles generated by discharging. In it, the total area of the opening 5 is made 1/3 or less of the total area of the surface of the discharge electrode including the opening portion 5, and the area of each opening 5 is made 5,000 μm2 or more and 40,000 μm2 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device used in an image forming apparatus such as an electrostatic recording system and an electrophotographic recording system.

[0002]

2. Description of the Related Art Conventionally, as a charging device used for an image forming apparatus such as an electrostatic recording system or an electrophotographic recording system, for example, Japanese Patent Application Laid-Open No. 10-31345 discloses an insulating substrate made of alumina or the like, A dielectric layer formed on the surface on the side of the member to be charged (such as a photoreceptor); an induction electrode covered with the dielectric layer; and an opening provided on the opposite side of the induction electrode with the dielectric layer interposed therebetween. A discharge electrode for providing a discharge area, a discharge power supply for applying an AC voltage between the induction electrode and the discharge electrode, and a bias power supply for applying a predetermined bias voltage between the discharge electrode and the member to be charged. Creepage corona discharger is disclosed. In this discharger, a creeping corona discharge is generated at an end of a discharge electrode in a discharge area, and positive and negative charged particles are generated in the vicinity thereof to charge an object to be charged (such as a photoconductor).

[0003]

However, a charging device using a discharger of the type described above applies a high AC voltage between an induction electrode and a discharge electrode in order to generate charged particles by discharge. because there, nitrogen oxides (NO _X) and ozone is generated together with the charged particles. In addition to the problem that these nitrogen oxides and ozone adversely affect the human body and the environment, in electrophotographic devices such as electrophotographic copying machines and printers, ozone floating in the device adheres to toner. The external additives are peeled off from the toner to form an insulating film on the photoreceptor, or the nitrogen oxide reacts with moisture in the air on the photoreceptor to disturb the latent image, adversely affecting the image. There is a problem that exerts.

[0004] As a means for solving these problems, there has conventionally been found an apparatus in which exhaust gas from an electrophotographic apparatus such as a copying machine or a printer is filtered by an ozone filter to remove nitrogen oxides and ozone. However, even with this method, nitrogen oxides and ozone cannot be completely removed.

[0005] Further, the problems required for the image forming apparatus include a problem of reducing the power consumption of the image forming apparatus and a FCOT (First Copy Output).
Time), that is, how to shorten the time required from when a copy command is given to the image forming apparatus to when the first copy is output.

In order to reduce the power consumption of the image forming apparatus, it is important to reduce the power consumption of a charging device having a large-sized high-voltage power supply device. It is necessary to uniformly charge the object to be charged by performing a uniform discharge, and it is necessary to simultaneously achieve several problems that the FCOT needs to be shortened.

Conventionally, in order to solve these problems, for example, Japanese Patent Application Laid-Open No. 61-27570 discloses a means for detecting a temperature in the vicinity of a discharge electrode in order to realize stable and uniform charging. A method of providing a heater for heating the vicinity of the electrode and controlling the heater based on the detected temperature is disclosed. JP-A-63-18372 discloses a method for quickly and efficiently performing uniform and stable discharge under a wide range of environmental conditions by providing a heating means for heating the vicinity of a discharge electrode. I have. Japanese Patent Application Laid-Open No. 63-132270 discloses a dielectric layer in which at least two electrodes for applying an AC voltage are embedded, a heating means for heating the dielectric layer, the temperature of the dielectric layer and its vicinity. There is disclosed a method of providing a temperature detecting means for detecting, and controlling the heating means in accordance with the output of the temperature detecting means to realize a uniform discharge. Japanese Patent Application Laid-Open No. 63-136060 discloses a current detecting means for detecting a charging current flowing through a member to be charged at the time of charging, and a uniformity by controlling a frequency of an applied power source for discharging in accordance with the detected charging current. A method for performing stable charging is disclosed. Japanese Patent Application Laid-Open No. 10-198124 discloses that a heating electrode is integrally formed on the same surface as an excitation electrode when manufacturing a charging device having a built-in heating means for heating a substrate around the excitation electrode. A method of reducing the number of parts and thereby reducing the cost is disclosed. In addition, 2-62
No. 862, etc., a linear discharge electrode is provided on the surface of an alumina substrate, a planar excitation electrode is buried inside the substrate, and the linear discharge electrode and the planar excitation electrode are interposed via a dielectric layer. An opposed surface corona discharge element is disclosed.

However, in any of the above methods,
Since a method of stabilizing discharge by increasing the temperature of the solid-state charger is employed, there is a problem that power consumption increases due to heating.

Regarding the shortening of the FCOT, for example, Japanese Patent Laid-Open No. 1-7071 discloses an effect on the photoreceptor by setting the temperature of the discharger to a lower temperature during non-discharge than during use. A method for realizing stable discharge while reducing FCOT while reducing the size is disclosed.

However, in the charging device of the image forming apparatus, since the discharger is provided so as to face the photoconductor, the temperature of the photoconductor is raised by increasing the temperature of the substrate during use. The service life may be shortened.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a low-cost charging device which generates less nitrogen oxides and ozone and can perform stable discharge without a heating means.

[0012]

According to a first aspect of the present invention, there is provided a charging device comprising a substrate made of an insulator, a plurality of excitation electrodes formed on the surface of the substrate, and the excitation electrodes. A dielectric layer covering the surface of the substrate, and a discharge electrode formed on the surface of the dielectric layer and having an opening at a position corresponding to the excitation electrode, and a predetermined drive is provided between the excitation electrode and the discharge electrode. In a charging device that discharges by applying a voltage and charges an object to be charged with charged particles generated by the discharge, the total area of the openings is 1 / the total surface area of the discharge electrode including the openings. 3 or less, and the area of each opening is 500
Wherein the 0μm is ² or more 40000Myuemu ² or less.

Here, the dielectric layer and / or the discharge electrode preferably contain titanium oxide.

According to a second charging device of the present invention for achieving the above object, a substrate made of an insulator, a plurality of excitation electrodes formed on the substrate surface, and a substrate surface on which the excitation electrodes are formed are provided. A dielectric layer to cover, a discharge electrode formed on the surface of the dielectric layer and having an opening at a position corresponding to the excitation electrode, and applying a predetermined drive voltage between the excitation electrode and the discharge electrode; In a charging device for performing discharge by charging a charged object with charged particles generated by the discharge, a drive voltage application time for storing a time when a drive voltage is applied between the excitation electrode and the discharge electrode It is characterized by comprising storage means, and drive voltage control means for controlling the drive voltage application condition based on the drive voltage application time stored in the drive voltage application time storage means.

Here, it is preferable that the driving voltage is an alternating voltage.

In a preferred embodiment, the drive voltage control means controls at least one of a peak voltage and a frequency of the drive voltage.

[0017]

Embodiments of the present invention will be described below.

FIG. 1 is a schematic configuration diagram of an embodiment common to the first charging device and the second charging device of the present invention.

As shown in FIG. 1, this charging device 10
A substrate 1 made of an insulator such as alumina; an excitation electrode 2 formed on the surface of the substrate 1; a dielectric layer 3 covering the surface of the substrate 1 on which the excitation electrode 2 is formed; And a discharge electrode 4 having an opening 5 at a position corresponding to the excitation electrode 2. The discharge is performed by applying an AC driving voltage from a driving power supply 6 between the excitation electrode 2 and the discharge electrode 4. Then, the charged object 7 is charged by the charged particles P generated by the discharge.

The charging device 10 includes a driving power source 6.
A drive voltage application time storage means 8 for storing the time during which the drive voltage applied between the excitation electrode 2 and the discharge electrode 4 is applied; and a drive voltage application time stored in the drive voltage application time storage means 8. And a drive voltage control means 9 for controlling conditions for applying a drive voltage from the drive power supply 6 based on the drive voltage.

FIG. 2 is a top view (a) of the charging device 10 shown in FIG. 1 and a cross-sectional view taken along line AA of FIG.

As shown in FIGS. 2A and 2B, the excitation electrode 2 has a linear shape, and a plurality of excitation electrodes 2 are formed on the substrate 1 in parallel. The entire substrate 1 on which the excitation electrode 2 is formed is covered with a dielectric layer 3, and a discharge electrode 4 is formed on the dielectric layer 3. A plurality of openings 5 are formed at positions corresponding to 2.

The total area of the plurality of openings 5 is not more than 1/3 of the entire surface area of the discharge electrode 4 including the openings 5, and the area of each of the openings 5 is 5000.
It is formed in a thickness of not less than ² μm ^{2 and not} more than 40000 μm ² .

Next, a method of forming the charging device will be described.

FIG. 3 is an explanatory diagram of a method of forming the charging device shown in FIGS.

First, as shown in FIG. 3A, a plurality of linear excitation electrodes 2 (FIG.
(See (a)). The excitation electrode 2 is formed by printing a material such as Au, Ag, or AgPd on the alumina substrate 1 by a thick film printing method and firing the material.

As a method of forming a conductive film for forming the excitation electrode 2, a conductive film of Au, AgPd, chromium, copper, tungsten, aluminum, platinum, titanium or the like is formed by a sputtering method or the like. A thin film method for re-patterning by photolithographic etching may be employed.

Next, as shown in FIG. 3B, the dielectric layer 3 is formed so as to cover the entire surface of the substrate 1 on which the excitation electrode 2 is formed.
To form The dielectric layer 3 is preferably formed of a dielectric layer having a low dielectric constant.

Further, the dielectric layer 3 is formed by a thick film printing method so that a pattern (see FIG. 2A) in which a plurality of holes (openings) 5 are formed at positions corresponding to the excitation electrodes 2 is formed.
The discharge electrode 4 is formed thereon by a thick film printing method using a Ni, Au or Al film or the like.

Here, in the first charging device of the present invention, the total area of the plurality of openings (holes) 5 is not more than 1/3 of the entire surface area of the discharge electrode 4 including the openings 5, and The area of each of the plurality of openings 5 is 5000 μm ²
The charging device is formed so as to have a thickness of 400000 μm ² or less.

Next, the area and shape of the hole of the opening 5 will be described.

Table 1 is a table showing the hole shape (a) and the individual hole area (b) of the opening 5 in the first charging device of the present invention.

[0033]

[Table 1]

As shown in Tables 1 (a) and 1 (b), there are six types of hole shapes (square, rectangular 1, rectangular 2, circular, elliptical 1, elliptical 2) and individual hole areas of 6 types. Kinds (4000, 5000, 10,000, 2000
6 × 6 = 36 of 0.40000, 50000 μm ² )
Various types of charging devices were manufactured.

FIG. 4 is a diagram showing a hole shape in the first charging device of the present invention.

As shown in FIG. 4, a charging device having discharge holes of various shapes as shown in FIG. 4 was prepared, and a discharge test was performed. The results were evaluated. Instead, the result was determined by the hole area.

FIG. 5 is a graph showing the relationship between the area of each hole and the amount of generated nitrogen oxides in the first charging device of the present invention, and FIG. 6 is a graph showing the relationship between each hole in the first charging device of the present invention. It is a graph which shows the relationship between hole area and ozone generation amount.

The graphs shown in FIGS. 5 and 6 show the results of a discharge test performed using the charging device shown in FIG. That is, when a driving voltage of AC 2 kV (peak to peak) 100 kHz is applied between the excitation electrode 2 and the discharge electrode 4, a creeping discharge occurs in the opening 5, and the gas in the air is ionized. The ions (negative ions or positive ions) are transferred from the opening 5 to the surface of the member 7 by a predetermined bias potential applied between the discharge electrode 4 and the member 7. The graphs shown in FIG. 6 and FIG.
It is a result of measuring a current flowing at that time and a gas amount of generated nitrogen oxides and ozone.

As shown in FIG. 5 and FIG.
Both the amount of generated ozone and the amount of generated ozone
With the increase in
The amount of these gases generated depends on the individual hole area,
Hole area of 40000μm^TwoTo 20000 μm^Two , 5
000 μm^Two Gas generation
It can be seen that the amount gradually decreases. But individual
Hole area is 5000μm ^Two When the current is less than
Does not increase to about 20 μA or more.
I stayed at a level that could not meet this performance
U. On the other hand, each hole area is 50,000 μm^Two Exceeds
The amount of generated gas, especially the amount of nitrogen oxides, increases rapidly.
Image quality defects.

As described above, the area of each hole is set to 5000 μm.
By setting the range of ² or more 40000Myuemu ² or less, nitrogen oxides and less generation of ozone gas, sufficient counter electrode inrush current is obtained, it is possible to discharge performance is good, and to obtain a charging device life .

Further, in the charging device 10 of the present embodiment, it has been found that the ratio of the total area of the openings 5 to the entire surface area of the discharge electrode 4 also has a large effect on the discharge performance and life of the charging device. If the ratio of the total area of the openings 5 to the entire surface area of the discharge electrode 5 exceeds 1/3, the life of the charging device 10 is significantly reduced.

Therefore, in the first charging device of the present invention, the total area of the openings is determined to be 1/3 or less of the entire surface area of the discharge electrode including the openings, and the area of each opening is set to 5000 μm. It is defined ^more 40000Myuemu ² or less.

From the results of the above-mentioned discharge test, it can be seen that titanium oxide is contained in the constituent material of the dielectric layer 3 and / or the discharge electrode 4 of the first charging device 10 of the present invention. It has also been found that the amount of generation decreases.

Table 2 shows the effect on the amount of generated nitrogen oxides depending on whether or not titanium oxide is added to the dielectric layer.

[0045]

[Table 2]

As shown in Table 2, the nitrogen oxide concentration of the sample (A) in which titanium oxide was not added to the dielectric layer was 3.286 ppm on average, whereas titanium oxide was added to the dielectric layer. In addition, the nitrogen oxide concentration of the sample (B) was 2.934 ppm on average, and the nitrogen oxide concentration was reduced by about 10% by adding titanium oxide to the dielectric layer. Furthermore, when titanium oxide was added to the discharge electrode, a reduction in the amount of generated nitrogen oxides by about 40% was observed. From the above results, it is preferable to add titanium oxide to the dielectric layer and / or the discharge electrode in order to further reduce the amount of nitrogen oxide generated in the charging device of the present embodiment.

Next, an embodiment of the second charging device of the present invention will be described.

The schematic configuration of the second charging device of the present invention has been described with reference to the schematic configuration diagram (see FIG. 1) of the embodiment common to the first and second charging devices of the present invention. Has a characteristic of the second charging device of the present invention,
Drive voltage application time storage means 8 and drive voltage control means 9
Will be described.

As described above, it is known that it is effective to heat or keep the substrate of the charging device in order to reduce the FCOT of the image forming apparatus. When the temperature is raised, it is necessary to sufficiently consider the thermal effect on the heat-sensitive photoconductor disposed at a position facing the charging device.

Therefore, the present inventors have focused on the relationship between the drive voltage applied between the excitation electrode and the discharge electrode during use and the substrate temperature of the charging device, and as a result of various studies, have found that the excitation electrode and the discharge electrode Drive voltage application time storage means for storing the time during which the drive voltage is applied, and drive voltage control for controlling the drive voltage application conditions based on the drive voltage application time stored in the drive voltage application time storage means The present invention has led to the invention of a second charging device according to the present invention, comprising:

The operation of the second charging device of the present invention will be described with reference to FIG.

When a driving voltage of AC 2 kV (peak-to-peak) 100 kHz is applied between the excitation electrode 2 and the discharge electrode 4 of the charging device 10, surface discharge occurs in the opening 5,
The gas in the air is ionized. The ions (negative ions or positive ions) are transferred from the opening 5 to the surface of the member 7 by a predetermined bias potential applied between the discharge electrode 4 and the member 7. At this time, it is known that if the distance between the discharge electrode 4 and the charged body 7 is 1 mm and the bias potential is -700V, the charged body 7 is charged to about -650V.

FIG. 7 is a diagram showing the results of a print test performed using the second charging device of the present invention.

FIG. 7A shows the driving voltage and the image quality of a print sample obtained from the image forming apparatus when the substrate temperature is maintained at 70 ° C. The driving voltage is 1.8 kVp.
In the case of p or more, good image quality was obtained in all three print samples, but it can be seen that, at a driving voltage of 1.7 kVpp, vertical stripes were partially generated due to insufficient charging of the charging device.

FIG. 7B shows the driving voltage and the image quality of the print sample obtained from the image forming apparatus when the substrate temperature is maintained at 55 ° C., and is substantially the same as FIG. 7A. The results have been obtained.

FIG. 7C shows the driving voltage and the image quality of the print sample obtained from the image forming apparatus when the substrate temperature is maintained at 40 ° C. The driving voltage is 1.9 kVp.
At p or more, good image quality is obtained for both print samples. However, when the driving voltage is 1.8 kVpp, vertical stripes are partially generated due to insufficient charging of the charging device. It can be seen that the image quality has deteriorated.

FIG. 7D shows the driving voltage and the image quality of the print sample obtained from the image forming apparatus when the substrate temperature is maintained at 25 ° C. At a driving voltage of 2 kVpp, good image quality is obtained. Drive voltage of 1.9 kV
Below pp, image quality is degraded due to insufficient charging.

As described above, it is understood that a driving voltage of 2 kVpp or more is required at 25 ° C., that is, at room temperature.

Next, using this charging device, the relationship between the discharge current flowing through the member to be charged at a distance of 1 mm from the discharge surface, the substrate temperature of the charging device, and the driving voltage was examined.

FIG. 8 is a graph showing the results of a discharge test performed using the second charging device of the present invention.

As shown in FIG. 8, the discharge current is 100 μA
It is understood that a sufficient charge amount can be obtained if the above is satisfied. Generally, when the process speed is increased, the discharge current needs to be increased. In this case, the relationship between the substrate temperature and the drive voltage is as shown in FIG.

FIG. 9 is a graph showing the results of a discharge test performed using the second charging device of the present invention.

In FIG. 9, as shown by the solid line, driving is first started with the drive voltage kept constant at 3 kVpp, and the substrate temperature gradually rises from room temperature (25 ° C.) as shown by the dashed line. An example is shown in which, when the temperature reaches 50 ° C., the drive voltage is reduced to about 1.7 kVpp to drive the substrate temperature so as not to increase further.

FIG. 10 is a graph showing a temporal transition of the driving voltage in the second charging device of the present invention.

FIG. 10 shows a state in which the drive voltage is controlled at an appropriate timing from, for example, Vppl to Vpp2. By controlling the drive voltage in this manner, good charging can be obtained even at room temperature, and the rise in substrate temperature can be suppressed to a predetermined level.

Therefore, in the second charging device of the present invention, as shown in FIG. 1, the charging device 10 is provided with the driving voltage application time storage means 8 and the driving voltage control means 9, and the driving voltage application time storage means is provided. 8 stores the time during which the drive voltage is applied between the excitation electrode 2 and the discharge electrode 4. Based on the drive voltage application time stored in the drive voltage application time storage means 8, the drive voltage control means 9 The voltage application condition is controlled.

In the second charging device of the present invention, an example in which the alternating voltage is used as the driving voltage has been described. However, the alternating voltage is not necessarily used.
DC voltage may be used. Furthermore, when the alternating voltage is used as the driving voltage, the control by the driving voltage control means 9 may be controlled not only by the peak voltage of the driving voltage but also by the frequency of the alternating voltage as in the above-described embodiment. It should be noted that increasing the peak voltage of the driving voltage and increasing the frequency of the alternating voltage have substantially the same effect.

[0068]

As described above, according to the first charging device of the present invention, the total area of the openings of the discharge electrode is set to 1/3 or less of the entire surface area of the discharge electrode including the opening. And the area of each opening is 5000 μm ²
By setting it to 40,000 μm ² or less, good charging can be obtained even at room temperature without providing a heating means in the charging device, and it is possible to suppress the rise in the substrate temperature, and the generation of nitrogen oxides and ozone is small. In addition, it is possible to realize a charging device that has a short FCOT and can perform stable discharge without a heating unit.

According to the second charging device of the present invention,
A drive voltage application time storage unit that stores a time during which the drive voltage is applied between the excitation electrode and the discharge electrode; and a drive voltage control unit that controls application conditions of the drive voltage based on the drive voltage application time. As a result, F
A charging device having a short COT and capable of performing stable discharge can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment common to a first charging device and a second charging device of the present invention.

2A is a top view of the charging device 10 shown in FIG. 1 and FIG.

FIG. 3 is an explanatory diagram of a method of forming the charging device shown in FIGS. 1 and 2.

FIG. 4 is a diagram illustrating a hole shape in the first charging device of the present invention.

FIG. 5 is a graph showing the relationship between each hole area and the amount of generated nitrogen oxides in the first charging device of the present invention.

FIG. 6 is a graph showing the relationship between each hole area and the amount of ozone generated in the first charging device of the present invention.

FIG. 7 is a diagram showing the results of a print test performed using the second charging device of the present invention.

FIG. 8 is a graph showing the results of a discharge test performed using the second charging device of the present invention.

FIG. 9 is a graph showing the results of a discharge test performed using the second charging device of the present invention.

FIG. 10 is a graph showing a relationship between a driving time and a driving voltage in the second charging device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Excitation electrode 3 Dielectric layer 4 Discharge electrode 5 Opening 6 Drive power supply 7 Charged body 8 Driving voltage application time storage means 9 Driving voltage control means 10 Charging device P Charged particle

Continuing from the front page (72) Inventor Takeshi Kengawa 2274 Hongo, Ebina-shi, Kanagawa Prefecture F-term in Fuji Xerox Co., Ltd. Ebina Works (reference) 2H003 AA12 AA18 BB11 CC01 DD03 DD05 EE10 EE12

Claims (5)

[Claims] A substrate formed of an insulator, a plurality of excitation electrodes formed on the substrate surface, a dielectric layer covering the substrate surface on which the excitation electrodes are formed, and a dielectric layer formed on the dielectric layer surface. A discharge electrode having an opening at a position corresponding to the excitation electrode, and performing a discharge by applying a predetermined drive voltage between the excitation electrode and the discharge electrode to cause a charged particle generated by the discharge. In the charging device for charging a member to be charged, the total area of the openings is １ ／ or less of the entire surface area of the discharge electrode including the openings, and the area of each of the openings is 5000 μm ² or more and 40000 μm. Charging device characterized by being ² or less. 2. The charging device according to claim 1, wherein the dielectric layer and / or the discharge electrode contain titanium oxide. 3. A substrate made of an insulator, a plurality of excitation electrodes formed on the substrate surface, a dielectric layer covering the substrate surface on which the excitation electrodes are formed, and a dielectric layer formed on the dielectric layer surface. A discharge electrode having an opening at a position corresponding to the excitation electrode, and performing a discharge by applying a predetermined drive voltage between the excitation electrode and the discharge electrode to cause a charged particle generated by the discharge. In a charging device for charging an object to be charged, a drive voltage application time storage unit that stores a time when a drive voltage is applied between the excitation electrode and the discharge electrode, and a drive voltage application time storage unit that stores the drive voltage application time storage unit. A charging device comprising: a driving voltage control unit configured to control an application condition of the driving voltage based on a driving voltage application time. 4. The charging device according to claim 3, wherein said driving voltage is an alternating voltage. 5. The charging device according to claim 4, wherein said drive voltage control means controls at least one of a peak voltage and a frequency of said drive voltage.