JP2000021550A - Discharge device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge device that accelerates the decomposition of gas by concentrating energy while securing a desired charge quantity and restrains the production of the gas generated in conjunction with discharge. SOLUTION: This device is composed by providing a plate-like board 11 formed from a dielectric, linear excitation electrodes 40 juxtaposed on the surface of the board 11, and discharge electrodes 50 having discharge opening parts 70 which are arranged corresponding to the excitation electrodes 40 through a dielectric 20. In this case, for the discharge opening parts 70 of the discharge electrodes 50, a dimension h1 of each of the opening planes of their surfaces facing to the excitation electrodes 40 is set larger than a dimension h2 of the upper opening plane, so that the shape of the discharge surfaces of the discharge electrodes 50 is so formed that their upper parts are shaped into a projecting form. The electric lines of force of the discharge opening parts 70 having such a shape are concentrated short in discharging so that electric field intensity is increased and the decomposition of a discharge gas by energy enhancement is accelerated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge device for performing discharge such as charging and discharging in an image forming apparatus using electrostatic recording, electrophotography, and the like, and in particular, suppresses ozone generated during discharge to a low concentration. Therefore, the present invention relates to a solid-state discharge device in which the electric field strength is increased and ozonolysis is promoted, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in this type of image forming apparatus, various discharge devices have been used for forming an image by charging an image carrier such as a photosensitive member. For example,
As a device for charging the image carrier, (1) a photoreceptor is charged by corona discharge using a corotron charger or a scorotron charger. (2) Creeping corona discharge is performed by a creeping corona discharge by a creeping discharge element of a linear excitation electrode disposed on the surface of an alumina substrate and a planar discharge electrode buried opposite to each other via a dielectric to charge the photosensitive member ( JP-A-54-53537, JP-A-59-53537
-44797). Etc.

Here, the discharge device (2) will be described with reference to FIG. A linear excitation electrode 4 (4
a, 4b, 4c, and 4d) are formed by directly forming a thick film by printing, or forming a conductive layer by a method such as sputtering, and then patterning by photolithographic etching. The excitation electrode 4 is connected to a power supply 5. Further, a discharge electrode 3 connected to a power supply 5 via a dielectric 2 is formed by the same method as the excitation electrode 4, and a protective film 6 is formed thereon to form a surface discharge element. By the way, in a discharge device and a creeping corona discharge element formed in this way, in addition to the problem that nitrogen oxides and ozone generated by discharge have a bad effect on a human body and an environment, in an image forming apparatus, Ozone floating inside peels off the external additive adhering to the toner, forms an insulating film on the photoreceptor, and has a problem of affecting the image.

To solve these problems, conventionally, an ozone filter was used to forcibly discharge nitrogen oxides and ozone inside an electrophotographic apparatus. However, it was not completely discharged. On the other hand, the concentration of nitrogen oxides and ozone
Since the decomposition of gas is promoted by applying energy to the discharge portion, a heating method has been proposed in which heat is applied from the outside to decompose these gases generated at the time of discharge (JP-A-60-79637). Reference).

[0005]

However, in the discharge device of the conventional image forming apparatus, the discharge device is arranged close to the image carrier in order to improve charging efficiency and the like. For this reason, in the heating method, there has been a problem that the temperature of the photoconductor rises due to heat applied to the discharge device, which causes deterioration of the photoconductor. Therefore, the discharge device and the method of manufacturing the same according to the present invention solve these problems, concentrate energy while maintaining a desired charge amount, promote gas decomposition, and suppress generation of gas generated by discharge. That is the task.

[0006]

According to the present invention, there is provided a discharge apparatus which has an excitation electrode (40) provided on a substrate (11) formed of a dielectric, and which faces the excitation electrode (40) via the dielectric. Discharge electrode (5) having a discharge opening (70)
0), and the discharge opening (70) of the discharge electrode (50) has a configuration in which the opening bottom surface (71) facing the excitation electrode (40) is larger than the opening upper surface. In the discharge device according to the present invention, when a discharge voltage is applied to the excitation electrode and the discharge electrode to generate a discharge from the discharge opening, the bottom of the opening facing the excitation electrode has a shape larger than the upper surface of the opening. Since the discharge surface is at an acute angle to the substrate and the length of the line of electric force can be shortened, the electric field intensity on the discharge surface is strong, energy is concentrated, and the discharge represented by ozone generated together with the discharge Gas decomposition is promoted.

In the method of manufacturing a discharge device by lift-off thick film printing according to the present invention, the substrate (1) on which the excitation electrode (40) is formed is formed.
1) A resist layer forming step of forming a resist layer (80) on a dielectric (20) via a dielectric (20);
A trapezoidal cured resist (81) in which the area of the bottom face facing the excitation electrode (40) is larger than the area of the top face via
The exposure step is to adjust the exposure conditions so as to form, for example, an exposure step of exposing the resist layer with the exposure conditions being overexposure, a development step of developing a cured resist (81) cured by exposure, and a discharge electrode layer (55). A step of forming a discharge electrode layer to be formed, a lapping step of removing an electrode material on the cured resist (81), and a discharge opening for burning the cured resist (81) to form an opening (70) in the discharge electrode layer (55). Forming step. Similar formation of a cured resist can also be achieved by adjusting the developing conditions in the developing step instead of adjusting the exposure conditions. When the discharge openings of the discharge electrodes are formed by photolithography, the discharge openings of the present invention are formed by selecting electrode materials having different etching rates.

According to these discharge device manufacturing methods, the exposure conditions in the discharge electrode manufacturing method by lift-off thick film printing are adjusted to overexposure or the developing conditions are set to insufficient development.
Alternatively, in the case of the photolithographic etching method, by disposing an electrode material having a high etching rate in the opening bottom layer, a discharge opening is formed in which the upper opening surface is smaller than the opening surface facing the excitation electrode. . Since the discharge opening of this shape makes the discharge surface an acute angle to the substrate and shortens the length of the line of electric force, the electric field intensity on the discharge surface is strong, energy is concentrated, and typical ozone is generated with discharge. A discharge device can be manufactured in which accelerated decomposition of the discharge gas is achieved.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 of the present invention will be described with reference to FIGS. 1 is a plan view of the discharge device, FIG. 2 is a cross-sectional view of a discharge opening of the discharge device showing a cross section taken along line AA of FIG. 1, FIG. 3 is an explanatory view of a discharge opening forming process, and FIG. It is an enlarged view.

The discharge device 10 includes a linear excitation electrode 40 made of Au formed by a thick film printing method on a central portion on a substrate 11 made of ceramic or alumina, and a discharge electrode 10 formed on the substrate 11 and the excitation electrode 40. A formed dielectric layer 20,
Discharge electrode 50 is provided on dielectric layer 20 and has opening 70 at a position corresponding to excitation electrode 40. The dielectric layer 20 is formed using a dielectric material having a dielectric constant lower than that of the substrate 11. The discharge electrode 50 is formed by stacking Ni or LaB ₆ films by a lift-off thick film printing method. An opening 70 is formed in the discharge electrode 50 at a position corresponding to the excitation electrode 40.

Here, the opening 70 is formed by a lift-off thick film printing method.
A method for forming the discharge electrode 50 having the following will be described with reference to FIGS. (1) The dielectric layer 2 is formed on the substrate 11 on which the excitation electrode 40 is formed.
0, and a resist is applied thereon to form a resist layer 8
0 is formed. ... Resist layer forming step (see FIG. 3A) (2) Using a mask 83 on which a pattern P corresponding to a discharge opening is drawn, the resist layer 8 is irradiated with ultraviolet rays S.
By exposing 0, a hardened resist 81 is formed on the excitation electrode 40. Exposure step (see FIG. 3 (b)) As shown in this figure, when the resist 80 is of a negative type, the portion of the resin irradiated with the ultraviolet rays S that has passed through the mask 83 is cured, and the cured resist 81 Become. At this time, the shape of the cured resist 81 is controlled by adjusting the exposure conditions. For example, overexposure is performed by increasing the exposure light amount by 10% to 20% of the normal light amount. Alternatively, overexposure is performed by setting the exposure time to twice the normal time. The formation of the cured resist 81 when the exposure condition is overexposure will be described. In the overexposed resist layer 80, the curing of the resist on the substrate 11 side proceeds due to the reflection of the ultraviolet rays from the substrate, and as shown in FIGS.
Dimensions h ₁ of 1 side bottom is against the upper side of the dimension h ₂ corresponding, the dimensions h _1> upper side of the dimension h ₂ relationship of the base, is formed into gentle mountain shape. (3) By developing the resist layer 80, the cured resist 81 formed in the exposure step remains on the dielectric layer 20. ...... Developing process (see FIG. 3 (c))

(4) Next, the dielectric layer 20 and the cured resist 81 are coated and a discharge electrode material 55 is laminated by a thick film printing method, and then dried. …… Discharge electrode layer forming step (FIG. 3)
(5) The discharge electrode material 55 covering the upper surface of the mountain-shaped resist 81 is scraped off. ...... Wrapping process (Fig. 3 (e)
In this step, when the discharge electrode material 55 is printed on the mountain-shaped cured resist 81 and baked in the next step, a film in which the thickness dimension of the discharge electrode material 55 is changed is formed. Not formed. Therefore, in this step, the discharge electrode material 55 formed on the mountain-shaped resist 81 is removed so that holes can be formed when the cured resist is baked in the next step. (6) Finally, the cured resist 81 is completely burned,
A discharge opening 70 having a mountain-shaped resist shape is formed in the discharge electrode 55. ... Discharge hole forming step (see FIG. 3 (f)) Then, although not shown, a protective layer is formed on the upper surface of the discharge electrode 50 such that a part of the discharge electrode in the opening 70 of the discharge electrode is exposed. Is formed.

The discharge electrode 50 thus formed is
At positions corresponding to the excitation electrode 40, a small upper dimension h ₂ with respect to the dimensions h ₁ of the base of the substrate side, a discharge opening 70 having a cross-sectional trapezoidal shape is formed. As a result, the discharge opening 70 of the discharge electrode 50 has an upper surface projecting toward the electrode surface, and has an opening surface corresponding to the excitation electrode 40 (opening bottom surface 7).
From 1), an inversely tapered cross-section is obtained in which the opening becomes smaller continuously toward the upper surface of the opening on the electrode surface.

In the above embodiment, the shape of the cured resist 81 is controlled by the exposure condition. However, the shape of the cured resist 81 may be controlled by the developing condition in the developing step. As adjustments in the development process, by shortening the development time and making the development insufficient,
The shape of the cured resist 81 is controlled.

In the discharge device 10 thus formed, the excitation electrode 40 and the discharge electrode 50 are connected to a high voltage power supply 60. The discharge device 10 is a discharge electrode 50 in the image forming apparatus.
Is disposed so as to face the image carrier which is the member to be charged. Then, a voltage is applied between the excitation electrode 40 and the discharge electrode 50 to generate discharge ions by corona discharge from the discharge opening 70 of the discharge electrode 50 toward the image carrier as a member to be charged. At this time, oxygen atoms generated in the ionization stage of air due to corona discharge react with oxygen molecules to generate ozone. The generated ozone is promoted to be decomposed by increasing the energy of the discharge portion as described above.

A description will now be given of the state of the energy of the discharge portion in the discharge device of the present invention in which the discharge opening 70 of the discharge electrode 50 has a shape in which the upper side protrudes toward the electrode surface. First, the state of electric field lines and electric field formation due to the difference in the shape of the discharge opening between the discharge device of the present invention and the conventional discharge device will be described with reference to FIG. FIG. 8 shows lines of electric force when the shape of the discharge surface of the discharge electrode disposed on the substrate 11 is changed. The discharge electrode 50 shown in (A) is the discharge electrode according to the present invention, and the angle θ formed between the substrate 11 and the discharge surface 501 of the electrode 50 is an acute angle. Electric lines of force of the discharge electrodes 50 of this shape, as shown by the broken line, the curved length of the electric line of force to the substrate 11 is L _1.
The discharge electrode 50B shown in (B) is a discharge electrode of a conventional discharge device, and the discharge surface 501B is perpendicular to the substrate (θ = 9).
0 °). Electric lines of force of the discharge electrode 50B of this shape becomes a greater curvature line with respect to the substrate 11 as shown by the broken line, the length of the lines of electric force longer L ₂ than L _1, the electric power lines L ₁ <electric lines of force L ₂ become. Discharge electrode 50C shown in (C)
Indicates a discharge electrode of a conventional discharge device, in which a discharge surface 501C forms a gentle curved surface, and an angle θ formed by the discharge surface 501C and the substrate 11 is an obtuse angle. Electric lines of force of the discharge electrode 50C of this shape becomes a line curved radius of curvature larger than the substrate 11 as shown by the broken line, the length of the electric lines of force becomes L _3. The length L ₃ of the electric flux line is longer than the length L _2. That is, the relationship of the lengths of the electric lines of force is such that the lines of electric force L ₁ <the lines of electric force L ₂ <the lines of electric force L ₃ .

Next, the relationship between the lines of electric force and the state of formation of the electric field will be described. The upper surface of the discharge opening of the present invention and the upper surface of the discharge opening of the conventional discharge device have a discharge opening 70 having the same shape in plan view as shown in FIG. 5, but the discharge electrode of the discharge device 10 according to the present invention. Since the discharge opening 70 has a trapezoidal cross section, the shape of the bottom surface 71 of the opening is larger than the upper surface of the opening as shown by a broken line. It has a protruding reverse taper shape. Therefore, FIG. 9 shows a state in which an electric field is formed at each height from the substrate layer of a discharge device having a discharge electrode 50 having a reverse tapered shape with respect to a substrate according to the present invention, and FIG. 5 shows a state in which an electric field is formed at each height from a substrate layer of a discharge device having a discharge electrode 50B perpendicular to FIG.

According to this experiment, the conventional discharge electrode 50B
Against 106V / [mu] m in height H _1, the height H ₁ from the substrate layer of the discharge electrodes 50 of the present invention 137
The electric field intensity is V / μm. Similarly, at the height H ₂ , the electric field intensity formed in the conventional discharge opening is 70
V / μm, the electric field strength of the present invention is 92 V / μm, and the height H ₃
, The electric field intensity formed in the conventional discharge opening is 54 V / μm, the electric field intensity of the present invention is 73 V / μm, and the electric field intensity formed in the conventional discharge opening is 42 V / μm at the height H ₄ . μm, and the electric field strength of the present invention is 56 V / μm.

As shown by the electric field strength due to the shape of the discharge opening, the electric field strength formed by the discharge electrode of the present invention is approximately equal to the electric field strength formed by the discharge electrode having a long line of electric force in the conventional discharge device. It is 30% stronger, indicating that the lines of electric force are concentrated. As described above, the electric field intensity is strong in the discharge opening 70 of the discharge electrode 50 according to the present invention during discharge, and energy is concentrated. As a result, the energy is increased and the decomposition of the discharge gas is promoted. Further, according to the present invention, since the electric field intensity is strong with respect to the applied discharge voltage, the discharge voltage can be suppressed low, and effective discharge can be performed with a low discharge voltage. Normally, ozone gas and the like are generated by air discharge, but the amount of ozone gas generated decreases by lowering the discharge voltage. In this way, the discharge device 10 can achieve a reduction in the amount of ozone gas generated due to a decrease in the discharge voltage, and can efficiently decompose the generated ozone and reduce the ozone concentration in the discharge portion. Then, when the ozone concentration at the time of discharge by this discharge device 10 was measured, the ozone concentration was reduced from ／ to 、 ２ as compared with the ozone concentration at the time of discharge by the conventional device.

As described above, in the discharge device 10 according to this embodiment, the discharge region can be expanded by making the discharge start voltage low, the electric field intensity is increased, and a desired charge amount is secured by efficient discharge. While reducing the generation of ozone gas and promoting the decomposition of the generated ozone, the ozone concentration can be reduced.

Embodiment 2 (see FIGS. 6 and 7) In the discharge device of this embodiment, a conductive film is formed on a substrate 11 by a technique such as spargling. Then, the conductive film is patterned by photolithographic etching to form a plurality of excitation electrodes 400. Examples of the conductive material of the conductive film include chromium, copper, tungsten, aluminum, platinum, titanium, and Au.

Next, a discharge electrode 500 is formed on the excitation electrode 400 via the dielectric layer 20. In this embodiment,
The discharge electrode 500 is formed by an etching method.
In forming the discharge electrode, first, a plurality of types of discharge electrode materials are stacked on the dielectric layer 20. The electrode materials to be laminated use materials having different etching rates, and in the etching process,
The shape of the discharge opening is formed such that the opening area of the discharge electrode layer facing the excitation electrode is large and the opening area of the other discharge electrode layers is small due to the difference in etching rate. Therefore, the material for forming the lower layer laminated on the dielectric layer 20 is a material having a higher etching rate than the material laminated for the upper layer,
An opening having a shape in which the bottom surface of the opening is large and the top surface of the opening is small is formed. In the embodiment shown in the drawings, the case where two types of materials are used is described. A first layer 51 laminated on the dielectric layer 20 and a second layer 5 laminated on the first layer 51;
3 and the electrode material forming the first layer 51 is the second electrode material.
The material has a higher etching rate than the electrode material forming the layer 53 of FIG.

A resist pattern 85 is formed on the second layer 53 using a photomask corresponding to the discharge opening. Next, etching is performed using the resist pattern 85 as a mask. At this time, since the material forming the first layer 51 has a higher etching rate than the second layer 53, the etching proceeds faster than the etching rate of the second layer. Thus, by the time the etching of the second layer 53 is completed along the resist pattern 85, the material of the first layer 51 is over-etched, and as shown in FIG.
The first layer 51 has a tapered shape whose top surface dimension is smaller than the bottom dimension on the substrate side. On the other hand, the second layer 5
3 is etched along the resist pattern 85.
As a result, the second layer 53 formed corresponding to the resist pattern 85 has a shape protruding with respect to the first layer 51, and the second layer 53 with respect to the opening dimension H 30 facing the excitation electrode 400. A discharge opening 700 having a reduced opening dimension H40 is formed.

The discharge device according to the present embodiment also has a discharge electrode 5 having a discharge opening 700 with a protruding upper part.
00, and the concentration is strong and the decomposition of the discharge gas is promoted. In addition, in the method of manufacturing this discharge device, by performing a normal etching process by selecting a material having a different etching rate, the bottom surface of the electrode opening of the electrode is larger than the upper surface of the opening, and the shape of the upper portion protrudes. Discharge opening 7
00 can be formed.

[0025]

As described above, in the discharge device of the present invention, the shape of the discharge opening is made larger at the bottom surface facing the excitation electrode than at the upper surface of the opening to increase the electric field strength at the time of discharge. Energy can be concentrated to reduce the generation of ozone and promote the decomposition of ozone while securing a desired charge amount. The manufacturing method of the discharge device of the present invention, the increase in the number of steps of the conventional manufacturing process, or without changing the process, exposure conditions, or adjustment of the development conditions, or by adjusting the electrode material, the electric field strength is strong, A discharge electrode that promotes ozonolysis can be formed.

[Brief description of the drawings]

FIG. 1 is a plan view of a discharge device.

FIG. 2 is a cross-sectional view of a discharge opening of the discharge device showing a cross section taken along line AA of FIG.

FIG. 3 is an explanatory view showing a manufacturing process of the discharge device.

FIG. 4 is a partially enlarged view of a resist forming step.

FIG. 5 is an enlarged plane of a discharge electrode.

FIG. 6 is an explanatory diagram of a manufacturing process of the discharge device according to the second embodiment.

FIG. 7 is a cross-sectional view of a discharge device in Embodiment 2.

FIG. 8 is an explanatory diagram of electric lines of force according to shapes of discharge electrodes.

FIG. 9 is an explanatory diagram of a state of forming an electric field at a discharge opening according to the present invention.

FIG. 10 is an explanatory diagram of a state of forming an electric field at a discharge opening of a conventional discharge electrode.

FIG. 11 is a sectional view of a conventional discharge device.

[Explanation of symbols]

Reference Signs List 10 discharge device, 11 substrate, 20 dielectric, 4
0,400 excitation electrode, 50,500 discharge electrode,
51 first layer, 53 second layer, 55 electrode material,
60 high voltage power supply, 70,700 discharge opening, 7
1 opening bottom, 80 resist, 81 cured resist exposed to ultraviolet rays, 83 photolithographic mask,
UV light passing through the P pattern and the S mask.

Claims (4)

[Claims] 1. A discharge comprising: a substrate formed of a dielectric; an excitation electrode provided on the substrate; and a discharge electrode having a discharge opening disposed to face the excitation electrode via the dielectric. In the discharge device, a discharge opening of the discharge electrode has a shape in which an opening surface of a bottom surface facing the excitation electrode is larger than an upper surface of the opening. 2. A discharge comprising: a substrate formed of a dielectric; an excitation electrode provided on the substrate; and a discharge electrode having a discharge opening disposed to face the excitation electrode via the dielectric. In the method for manufacturing a device, a resist layer forming step of forming a resist layer via a dielectric on the substrate on which the excitation electrode is formed, an exposing step of exposing the resist layer through the pattern of the discharge opening, A developing step of developing the cured resist,
A discharge electrode layer forming step of forming an electrode layer made of an electrode material on the dielectric and the cured resist, a lapping step of removing the electrode material on the cured resist, and burning the cured resist to form the discharge electrode layer A discharge opening forming step of forming an opening, wherein the exposing step adjusts exposure conditions so as to form a cured resist in which the area of the bottom surface facing the excitation electrode is larger than the area of the upper surface. Manufacturing method. 3. A discharge comprising: a substrate formed of a dielectric; an excitation electrode provided on the substrate; and a discharge electrode having a discharge opening disposed opposite to the excitation electrode via the dielectric. In the method for manufacturing a device, a resist layer forming step of forming a resist layer via a dielectric on the substrate on which the excitation electrode is formed, an exposing step of exposing the resist layer through the pattern of the discharge opening, A developing step of developing the cured resist,
A discharge electrode layer forming step of forming an electrode layer made of an electrode material on the dielectric and the cured resist, a lapping step of removing the electrode material on the cured resist, and burning the cured resist to form the discharge electrode layer A discharge opening forming step of forming an opening, wherein the developing step is performed by adjusting developing conditions so as to form a cured resist in which the area of the bottom surface facing the excitation electrode is larger than the area of the upper surface. Manufacturing method. 4. A discharge comprising: a substrate formed of a dielectric; an excitation electrode provided on the substrate; and a discharge electrode having a discharge opening disposed to face the excitation electrode via the dielectric. In the method for manufacturing a device, a step of forming a first discharge electrode layer via a dielectric on a substrate on which the excitation electrode is formed; and a step of forming an electrode material of the first discharge electrode on the first discharge electrode layer. Forming a discharge electrode layer made of an electrode material having an etching rate lower than an etching rate, and an etching step of etching the discharge electrode layer through the pattern of the discharge opening, In the etching step, the opening rate of the discharge electrode layer facing the excitation electrode is increased by increasing the etching rate of the first discharge electrode layer facing the excitation electrode in comparison with the etching rate of the other discharge electrode layers. Increasing the product, method of manufacturing the discharge device to reduce forming the opening area of the other discharge electrode layers.