JPH0734432Y2 - Corona discharge device and shield for corona discharge device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a corona discharge device in an image forming apparatus such as an electrophotographic copying machine and a laser printer.

[Prior Art] A commonly used electrophotographic copying machine has a structure as shown in FIG.

That is, a document table 20 on which a document 19 to be copied is placed is provided above a drum-shaped charge receptor 18 having a photoconductor layer formed on an aluminum substrate. 19
Light source 21 that illuminates the
An optical system 22 leading to 18 is installed. First, the charge acceptor
The surface of 18 is uniformly charged by the charging device 23 before the image information is irradiated, and the electrostatic latent image formed on the surface of the charge receptor 18 in the next exposure step is the charge receptor. After being developed into a toner image by the developing device 24 installed in the vicinity of 18, the toner image reaches the transfer device 25, and the toner image is transferred to the paper 27 fed from the paper feeding device 26. Paper with toner image transferred 27
Is removed by the peeling charging device 28, peeled off from the charge acceptor 18, and sent to the fixing device 29. The fixing device 29 fixes the toner image on the paper 27 to the paper 27. After the transfer step, the untransferred toner remaining on the surface of the charge receptor 18 is discharged by the precleaning corotron 30 and removed from the surface of the charge receptor 18 by the cleaning device 31. Further, the charge acceptor after the toner transfer is a corona charging device (not shown) for static elimination.
Is used for reuse by removing the residual charge with a static elimination lamp.

A corona discharge device used for charging and discharging in such an electrophotographic copying machine is a discharge device called a corotron whose perspective view is shown in FIG. 7 and whose schematic sectional view is shown in FIG. A pair of insulating blocks 11 is arranged at both ends of 10, and both ends of the thin discharge wire 12 are fastened to the pair of insulating blocks 11 with screws 13 via washers 13a and stopped, and a predetermined tension is applied and stretched. The thing is typical.

A discharge wire that generates a corona discharge usually has a wire diameter of 10
Since a metal wire such as a thin tungsten wire of 0 μm or less is used and it determines the corona discharge characteristics, it is necessary to attach it accurately with a constant tension without damaging the wire itself or attaching dirt. is there. Also,
The discharge wire that generates the corona discharge is contaminated with discharge products and a developer accompanying the discharge. As a result, the surface of the photoconductor becomes non-uniformly charged, and unevenness occurs in the toner image. In order to improve this, a discharge device called a scorotron provided with a screen 15 for controlling the discharge current between the discharge wire 12 and the photoconductor 18 as shown in a schematic sectional view in FIG. It is used.

In corotrons and scorotrons that generate these corona discharges, corona discharges are performed in the air, and ozone is generated by the reaction between oxygen active particles and oxygen molecules generated by the inelastic collision of charged particles and oxygen molecules accelerated in the discharge field. Known to produce. The air containing ozone is discharged from the exhaust unit installed in the electrophotographic copying machine to the outside of the machine, but ozone is a gas with a very strong odor, and people with ozone at a concentration of 0.1 ppm in the air for a long period of time. Contact with it may cause physiological effects such as shortness of breath, dizziness, headache, nausea, etc., which is harmful to the human body and is a major drawback of office equipment.

Conventionally, as a means for removing or reducing ozone discharged from an electrophotographic copying machine, for example, air containing ozone is decomposed through a layer space having a large contact area by filling an ozone decomposing substance or fixing it on a non-woven fabric in the discharging process. There is a way. As another example, a catalyst such as manganese dioxide, lead peroxide, palladium, platinum, nickel, or an ozone decomposition catalyst supporting metal oxides such as rhodium is dispersed on water on activated carbon powder, and this is dispersed in water. There is a method of reducing ozone in the corotron by using the one coated and dried on the shield surface. It has also been proposed to use a sheet made of activated carbon fiber or powdered activated carbon (hereinafter, both are collectively referred to as activated carbon paper) as an ozone decomposing substance used on the shield surface of such a corotron.

[Problems to be Solved by the Invention] A shield made of such activated carbon paper may deform or warp the sheet due to moisture absorption in the environment or the like, thereby impairing the performance of the corona discharger. Further, even during drying, the shape may be shrunk or warped, the edges of the sheet may be frayed or fluffed to cause deterioration of corona discharge performance and spark discharge.

Therefore, as shown in a perspective view in FIG. 10 (a) and a partially enlarged view in FIG. 10 (b), three activated carbon papers (outer liner 1, inner liner 2 and core 3) are formed into a cardboard shape. The processed one is also used.

In the conventional corrugated activated carbon shield, the parallelism of both sides of the shield is non-uniform, and the shield side surface is easily deformed due to environmental changes or external force, resulting in extremely weak shape retention. And the corona discharge becomes non-uniform, resulting in uneven charge amount of the photoconductor and uneven toner image.

Therefore, the object of the present invention is to solve the above-mentioned drawbacks of the corona discharge device provided with a shield in which activated carbon paper is laminated or processed into a corrugated shape, to enhance the O ₃ adsorption performance of the shield itself, and at the same time, at a low cost. An object of the present invention is to provide a corona discharge device and a shield for the corona discharge device, which can enhance the rigidity and keep the corona discharge performance stable for a long period of time.

[Means for Solving the Problems] The present invention has a structure in which a discharge wire, a discharge wire fixing portion provided at an end portion of the discharge wire, and a surface of the discharge wire, which faces each other, are bent to form a gutter shape. In a corona discharge device provided with a shield member made of a sheet having a uniform thickness, at least the shield member surface is formed of activated carbon paper, and at least a part of the thickness of the bent portion of the sheet is cut out to form a curable resin. A corona discharge device, and a discharge wire, a discharge wire fixing portion provided at an end portion of the discharge wire, and a gutter shape in which each surface is disposed so as to face the discharge wire. A shield member for use in a corona discharge device comprising a shield member made of a sheet having a bent thickness, wherein at least the shield member surface is formed of activated carbon paper, and The corona discharge device shield is characterized in that at least a part of the thickness of the bent portion of the gutter is cut out and replaced with a curable resin.

Examples of the sheet-like material include a laminated-type sheet-like material having at least the surface of activated carbon paper, a corrugated cardboard sheet formed of activated carbon paper, and the like.

[Effect of the Invention] The present invention is a sheet-like object whose surface is formed of activated carbon paper,
In addition, the bent portion (corner) of the shield is fixed with an ultraviolet curable resin or a thermosetting resin to enhance the rigidity and shape retention of the sheet-like activated carbon shield. The parallelism can be made uniform to prevent deformation due to an external force, the spatial distance to the discharge wire can be kept uniform, and stable discharge performance can be maintained for a long period of time.

[Examples] Hereinafter, the present invention will be described with reference to the drawings based on examples of a shield made of activated carbon paper processed into a corrugated cardboard. However, the present invention is not limited to the following examples, and activated carbon is present at least on the surface. Naturally, a laminated type shield provided with paper is also included in the scope of the present invention.

Embodiment 1 FIG. 1 (a) is a perspective view of an embodiment of the present invention, and FIG. 1 (b) is an enlarged cross-sectional view of a corrugated cardboard shield in which a notch is formed in a corner portion thereof before being strengthened, FIG. 1 (c) is an enlarged view of a corner portion of the embodiment of the present invention.

Outer liner 1 in corrugated activated carbon shield
A cut is made in the shield longitudinal direction from the apex of the corner to the corner of the inner liner 2. The cut amount at this time is such that the inner liner 2 is not cut off. FIG. 1 (b) shows such a cut state. Therefore, the inner right side liner 2b and the inner left side liner 2c are held at a right angle with respect to the inner upper surface liner 2a, and UV (ULTRA VIOLET) curability is applied to the corner portion opened by the cut as shown in FIG. 1 (c). Apply resin. This UV curable resin has a viscosity of 5,00
In the range of 0 to 100,000 cps, the curing reaction reference wavelength is, for example, 365
nm version is available.

As shown in the perspective view of FIG. 2, the coating method is such that the UV curable resin is put in advance in a container having a tip nozzle 5a of a dispenser 5 or the like having a diameter of 0.1 to 2 mm, and a pressure of 0.5 to 5 kg is applied inside the container.
/ cm ² of UV curable resin 4 is evenly extruded in a uniform amount and is applied at a constant speed in the longitudinal direction of the shield. Next, as shown in FIG. 3, the corrugated shield with the UV curable resin applied to both corners is placed in the UV irradiation device.

The output of the UV irradiation device is 0.4-2kw, and the wavelength of the irradiation light is 36
Based on the 5 nm peak. At this time, the light source distance to the irradiation body is set to 10 to 150 mm, and the resin is cured during the irradiation time of 5 to 120 seconds.

Due to this resin curing, the outer liners 1a and 1b, the inner liners 2a and 2b, and the inner cores 3a and 3b are exposed to UV light at the bent portions at right angles.
It is reinforced and held by the curable resin, and the rigidity of the corrugated cardboard-like activated carbon shield is enhanced.

Embodiment 2 FIG. 4 is a perspective view of another embodiment of the present invention. In this embodiment, a thermosetting resin 9 is used instead of the UV curable resin 4 of the above-mentioned embodiment 1, and the constitution is the same as that of the above-mentioned embodiment 1. That is, in the corrugated cardboard-like activated carbon shield, a cut is made in the shield longitudinal direction from the corner apex of the outer liner 1 toward the corner of the inner liner 2. The depth of cut at this time is such that the inner liner 2 is not cut off. Here, the liners 2b and 2c are held at a right angle with respect to the inner liner 2a, and the thermosetting resin 9 is applied to the corners opened by cutting. As the thermosetting resin, for example, a melamine resin, a urea resin, a one-component epoxy resin, a two-component epoxy resin or the like having a viscosity of 5,000 to 100,000 cps is used.

The coating method is the same as in the case of the UV curable resin of the above embodiment (see FIG. 2), and the tip nozzle diameter of the dispenser 5 and the like is 0.
Put thermosetting resin in a container of 1-2 mm in advance, apply 0.5 to 5 kg / cm ² of pressure to the inside of the container to extrude the thermosetting resin evenly in a fixed amount, and apply it at a constant speed in the longitudinal direction of the shield. To go. Insert the cardboard-like activated carbon shield with both sides coated with thermosetting resin into a heat dissipation device such as an electric furnace, and set the furnace temperature at 50 to 200 ° C to ± 10 ° C. The time for leaving in the furnace is 10 to 60 minutes, and heat is applied to the thermosetting resin.

By this heating, the outer liners 1a and 1b, the inner liner
The cores 2a and 2b and the cores 3a and 3b are reinforced and held by the right angle state and the thermosetting resin, and the rigidity of the corrugated cardboard-like activated carbon shield can be increased.

Embodiment 3 FIG. 5 (a) is a sectional view of a preferred embodiment of the present invention in which the outer corner portion and the inner corner portion of the shield are reinforced with a cured resin.

In the case where only the outer corners are reinforced with the cured resin as in the first and second embodiments, the shape of the shield is maintained when the tension load of the discharge wire is large and when the discharge wire is exposed to a hot and humid environment for a long time. This may result in warping in the axial direction of the shield wire, spread of the shield opening, and waviness, which not only makes it impossible to uniformly charge the photoreceptor, but also causes spark discharge.

Therefore, in this example, as shown in FIG. 5 (b), the rigidity of the shield is reinforced by applying a hardening resin to the inside corner of the shield in an amount that does not affect the discharge by the wire. That is, when the UV curable resin or the thermosetting resin described in Examples 1 and 2 is R _{0 for} the distance from the discharge wire to the shield and B for the distance from the discharge wire to the inner corner, the coating amount A Is applied in an amount of A ≦ B−R ₀ . As the curing agent used in this case, a conductive adhesive having a volume resistance of 10 ⁰ to 10 ⁴ Ω · cm is preferable.

[Brief description of drawings]

FIG. 1 (a) is a perspective view of an embodiment of the present invention, FIG. 1 (b) is an enlarged view of a shield before being strengthened with a notch in a shield corner, and FIG. 1 (c) is of the present invention. Enlarged view of the corner of the embodiment, FIG. 2 is a perspective view showing the state of application of UV curable resin, FIG. 3 is a sectional view showing the layout of UV irradiation, and FIG. 4 is the present invention using thermosetting resin. 5 is a perspective view of an embodiment, FIG. 5 (a) is a sectional view showing another embodiment of the present invention, FIG. 5 (b) is an explanatory view of the amount of curing agent applied, and FIG. 6 is a conventional electrophotographic copying. Fig. 7 is a perspective view of a conventional corona discharge device, Fig. 8 is a schematic sectional view of another conventional corona discharge device, and Fig. 9 is a schematic view of another conventional corona discharge device. FIG. 10 (a) is a perspective view of a shield of a corona discharge device using a conventional corrugated carbon shield, and FIG. 10 (b) is a sectional view of the structure. Is a partially enlarged cross-sectional view. Symbols in the figure: 1 …… Activated carbon paper outer liner; 2 …… Activated carbon paper inner liner; 3 …… Activated carbon paper core; 4 …… Ultraviolet (UV) curable resin; 5 …… Dispenser; 5a …… Dispenser nozzle;
6 …… UV irradiation device; 7 …… Reflecting mirror; 8 …… Light source lamp; 9 ……
Thermosetting resin; 10 …… Shield; 11 …… Insulation block; 12
...... Discharge wire; 13a ...... washer; 13 ...... screw; 14a, 14b, 14c
...... Power supply; 15 ...... Screen; 18 ...... Charge receptor; 19 ......
Manuscript; 20 ... Original plate; 21 ... Light source; 22 ... Optical system; 23 ... Charging device; 24 ... Developing device; 25 ... Transfer device; 26 ... Paper feeding device; 27
…… Paper; 28 Peeling device; 29 …… Fixer; 30 …… Pre-cleaning corotron; 31 …… Cleaning device.

Front page continuation (72) Kenji Saida, 17-9 Nihonbashi Koamicho, Chuo-ku, Tokyo Toyobo Co., Ltd. Tokyo Branch (72) Eiji Yoshimura 2-1-1 Katata, Otsu, Shiga Toyobo Co., Ltd. Corporate Research Institute (56) Reference JP-A-63-208070 (JP, A) Actually open 57-3607 (JP, U) Actually open 57-169624 (JP, U) Actually open 57-196626 (JP , U)

Claims (6)

[Scope of utility model registration request] 1. A shield comprising a discharge wire, a discharge wire fixing portion provided at an end portion of the discharge wire, and a sheet having a thickness bent in a gutter shape, each surface of which faces the discharge wire. In a corona discharge device including a member, at least the shield member surface is formed of activated carbon paper, and at least a part of the thickness of the bent portion of the sheet is cut out and replaced with a curable resin. Corona discharge device. 2. The corona discharge device according to claim 1, wherein the bent portion of the shield member is also reinforced from inside by a curable resin. 3. The corona discharge device according to claim 1, wherein the curable resin is a thermosetting resin or a UV curable resin. 4. A shield comprising a discharge wire, a discharge wire fixing portion provided at an end portion of the discharge wire, and a sheet having a thickness bent in a gutter shape, each surface of which faces the discharge wire. A shield member used in a corona discharge device including a member, wherein at least the shield member surface is formed of activated carbon paper, and at least a part of the thickness of the bent portion of the sheet is cut out and made of a curable resin. Corona discharge device shield characterized by being replaced. 5. The shield for a corona discharge device according to claim 4, wherein the shield is also reinforced from inside by curable resin along the edge line of the bent portion. 6. The shield for a corona discharge device according to claim 4, wherein the curable resin is a thermosetting resin or a UV curable resin.