JP2009294478A - Electrifying device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrifying device capable of obtaining stable electrifying performance by preventing irregular electrification, and to provide an image forming apparatus equipped therewith. <P>SOLUTION: The electrifying device includes a conductive holding body and a discharge electrode held by the conductive holding body, and uniformly electrifies a surface of a latent image carrier of the image forming apparatus by generating discharge between an edge or surface of the discharge electrode to which electrifying bias is applied and the latent image carrier through a gap, wherein discharge is generated between the discharge electrode and the latent image carrier through an electrode which has a plurality of apertures opposed to the edge or the surface of the discharge electrode and to which bias having a different value from the electrifying bias is applied. The discharge electrodes are arranged in shape of a brush while they are bundled, the edge of each in the bundle of the discharge electrodes is cut obliquely, and the edge part of the bundle of the discharge electrodes is arranged at some pitch. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charging device used for image formation, such as a copying machine, a printer, and a fax machine, and an image forming apparatus including the charging device.

Conventionally, a scorotron charger is known as a charging device. The scorotron charger includes a mesh-like grid electrode that faces the latent image carrier via a predetermined gap, and a wire that is stretched in such a manner that its peripheral surface faces the latent image carrier via the grid electrode. It has. When a predetermined bias is applied to the wire and a bias having a value closer to the uniform charging potential of the photoconductor than the bias is applied to the grid electrode, the wire is placed between the peripheral surface of the wire and the photoconductor. Corona discharge occurs. By this corona discharge, the surface of the photoreceptor is uniformly charged with the same polarity as the bias applied to the wire. In such a configuration, in order to generate corona discharge between the wire and the latent image carrier, it is necessary to apply a high voltage of 5 [kV] or more to the wire.
On the other hand, in Patent Document 1, a sawtooth discharge electrode having a plurality of sharp teeth is used instead of a wire as a member that generates a discharge while facing a latent image carrier via a mesh-like grid electrode. A charging device is disclosed. In such a configuration, in the discharge electrode to which a bias is applied, the electric charge is concentrated on a plurality of sharp teeth facing the grid electrode, so that the voltage is lower than that of a stretched wire type scorotron charger. Corona discharge can be generated.

However, in this charging device, the discharge is generated only from the tooth tip of the saw-tooth discharge electrode facing the grid electrode, so that charging due to poor charging of the non-face facing portion of the latent image carrier is performed. It was easy to cause unevenness. Although it is possible to suppress charging unevenness to some extent by making the tooth interval as small as possible, there is a limit to reducing the interval.
As described above, corona discharge can be generated at a voltage lower than that of the scorotron charger, but a voltage of 4 [kV] or more is still necessary, and further improvement is desired from the viewpoint of lowering the potential. It was.
A charging device using a carbon nanotube as a charging member for uniformly charging a photoconductor and emitting electrons from a nanometer-order through hole of the carbon nanotube to which a charging bias is applied toward the photoconductor is proposed. (For example, refer to Patent Document 2).
However, in this method, in order to emit electrons from the through holes of the carbon nanotubes toward the photoreceptor, it is necessary to place the carbon nanotubes and the photoreceptor in a reduced pressure environment close to vacuum. Since it is extremely difficult to create such a reduced pressure environment in a printer that passes recording paper, such a method lacks practicality. In addition, even if electrons can be emitted well from the through holes of the carbon nanotubes, the toner is likely to be clogged in the printer in which the toner is scattered, so that the charging performance is stable over a long period of time. It seems difficult to maintain.

In response to this, Patent Document 3 proposes a non-contact brush charging machine using micro-order conductive fibers. Compared to a wire (φ60 μm) or a saw tooth (50 μm thickness), since a thin electrode is used, low energy charging is possible.
However, in the case of an electrode in which the woven fiber is sandwiched between metals or films, variations occur at the tip of the electrode. The variation causes a difference in the discharge start voltage between the electrodes, resulting in unevenness in the longitudinal direction of the photoreceptor.
FIG. 12 shows a process for processing a braided brush. As a general processing method, a production method is adopted in which a knitted fiber bundle is sandwiched between holding bodies. In this method, the fiber bundle sandwiched between the holding bodies spreads toward the tip.

JP 2006-243286 A JP 2001-250467 A JP 2007-063975 A

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a charging device capable of preventing charging unevenness and obtaining stable charging performance, and an image forming apparatus including the charging device. It is said.

The features of the present invention, which is a means for solving the above problems, are listed below.
The charging device of the present invention includes a conductive holder and a discharge electrode held by the conductive holder, and a gap is formed between the tip or surface of the discharge electrode to which a charging bias is applied and the latent image carrier of the image forming apparatus. A charging device for uniformly charging the surface of the latent image carrier by causing discharge through the discharge electrode, and having a plurality of openings opposed to the tip or the surface of the discharge electrode and different from the charging bias In a charging device that generates a discharge between the discharge electrode and the latent image carrier through an electrode to which a bias of a value is applied, the discharge electrodes are arranged in a brush shape while forming a bundle, Each of the discharge electrode bundle tips is cut obliquely, and the discharge electrode bundle tip portions are arranged with a pitch.
Further, the charging device of the present invention is further characterized in that the discharge electrodes are arranged in a line to form an electrode bundle.
The charging device of the present invention is further characterized in that the discharge electrode has a cylindrical shape.
Further, the charging device of the present invention is further characterized in that the electrode tip is arranged in a spiral shape.
Further, the charging device of the present invention is further characterized in that the electrode and the conductive holding body are detachable.
The charging device of the present invention is further characterized in that one electrode unit is constituted by a plurality of electrodes.
An image forming apparatus according to the present invention includes any of the above-described charging devices.

According to the first aspect of the present invention, since the discharge occurs at the more protruding tip (where the difference in electric field strength is large) by cutting the tip of the brush obliquely, the discharge location can be specified. By arranging the discharge points at the same pitch, uneven charging can be suppressed. Here, description will be made using equipotential lines in FIG. When the electrode tips are close to each other, the equipotential electrode tips interfere with each other, and the “inclination of the electric field strength” in the field becomes small. When the tip of the brush is cut obliquely, the area around the tip of the electrode becomes sparse, and the “gradient of electric field strength” increases. Moreover, since the electrode bundle has a width, it is difficult to specify from which position in the electrode bundle the discharge is performed. On the other hand, it is possible to specify the discharge location by cutting the fiber tip obliquely.
According to the second to fourth aspects of the present invention, since the number of electrodes is reduced around the discharge point, the discharge can be performed with a smaller applied voltage. That is, the energy can be reduced.
The invention according to claim 5 can be easily repaired without damaging the electrode when discharge variation (charging unevenness) due to electrode contamination with time or electrode deterioration occurs. Compared with the replacement of one charging brush, the cost can be reduced.
According to the sixth aspect of the present invention, when performing electrode replacement for discharge variation (charging unevenness) due to local contamination by toner or fixing unit silicon vapor floating in the machine, a plurality of electrode replacements are performed collectively. Is possible, and it does not require time and effort.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for those skilled in the art to make other embodiments by changing or modifying the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of an electrophotographic printer (hereinafter simply referred to as a printer) will be described.
First, a basic configuration of the printer according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram illustrating a printer according to the present embodiment. This printer includes four process units 1Y, C, M, and K for yellow, cyan, magenta, and black (hereinafter referred to as Y, C, M, and K). These use Y, C, M, and K toners of different colors as image forming substances for forming an image, but the other configurations are the same. Taking a process unit 1Y for generating a Y toner image as an example, this has a photoconductor unit 2Y and a developing unit 7Y as shown in FIG. As shown in FIG. 3, the photosensitive unit 2Y and the developing unit 7Y are integrally attached to and detached from the printer body as a process unit 1Y. However, in a state where it is detached from the printer main body, as shown in FIG. 4, the developing unit 7Y can be attached to and detached from a photoreceptor unit (not shown).

In FIG. 2 described above, the photoconductor unit 2Y includes a drum-shaped photoconductor 3Y serving as a latent image carrier, a drum cleaning device 4Y, a static eliminator (not shown), a charging device 5Y, and the like. As the photoreceptor 3Y, an organic photoreceptor having a multilayer structure in which a charge generation layer and a charge transport layer are coated on the peripheral surface of an aluminum tube is used, but a single layer structure may be used.
The charging device 5Y uniformly charges the surface of the photoreceptor 3Y that is driven to rotate in the clockwise direction in the drawing by a driving unit (not shown). The surface of the photoreceptor 3Y uniformly charged by the charging device 5Y is exposed and scanned by a laser beam emitted from an optical writing unit to be described later, and carries a Y electrostatic latent image.
The developing unit 7Y as developing means has a first agent accommodating portion 9Y in which a first conveying screw 8Y is disposed. Further, it also has a second agent storage portion 14Y in which a toner concentration sensor (hereinafter referred to as a toner concentration sensor) 10Y composed of a magnetic permeability sensor, a second conveying screw 11Y, a developing roll 12Y, a doctor blade 13Y, and the like are disposed. . In these two agent storage portions, a Y developer (not shown) composed of a magnetic carrier and a negatively chargeable Y toner is included. The first transport screw 8Y is driven to rotate by a driving unit (not shown), thereby transporting the Y developer in the first agent storage unit 9Y from the near side to the far side in the direction perpendicular to the drawing sheet. And it penetrates into the 2nd agent accommodating part 14Y through the communication port which is not shown in the partition wall between the 1st agent accommodating part 9Y and the 2nd agent accommodating part 14Y.

  The second transport screw 11Y in the second agent storage portion 14Y is driven to rotate by a driving means (not shown), thereby transporting the Y developer from the back side to the front side in the drawing. The Y developer during conveyance is detected by the toner concentration sensor 10Y fixed to the bottom of the second agent container 14Y. In this manner, the developing roll 12Y is arranged in a posture parallel to the second transport screw 11Y above the second transport screw 11Y that transports the Y developer. The developing roll 12Y includes a magnet roller 16Y in a developing sleeve 15Y made of a non-magnetic pipe that is driven to rotate counterclockwise in the drawing. A part of the Y developer conveyed by the second conveying screw 11Y is pumped up to the surface of the developing sleeve 15Y by the magnetic force generated by the magnet roller 16Y. Then, after the layer thickness is regulated by the doctor blade 13Y disposed so as to maintain a predetermined gap from the developing sleeve 15Y as a developing member, the layer thickness is regulated and conveyed to the developing area facing the photosensitive member 3Y. Y toner is adhered to the Y electrostatic latent image. This adhesion forms a Y toner image on the photoreceptor 3Y. The Y developer that has consumed the Y toner by the development is returned to the second conveying screw 11Y as the developing sleeve 15Y of the developing roll 12Y rotates. And if it conveys to the near end in a figure, it will return in the 1st agent accommodating part 9Y via the communication port which is not shown in figure.

  The result of detecting the magnetic permeability of the Y developer by the toner concentration sensor 10Y is sent as a voltage signal to a control unit (not shown). Since the magnetic permeability of the Y developer shows a correlation with the Y toner density of the Y developer, the toner density sensor 10Y outputs a voltage having a value corresponding to the Y toner density. The control unit includes a data storage means such as a RAM, in which a V Vref for Y which is a target value of the output voltage from the toner density sensor 10Y, and C, M, and K mounted on other developing units. The data of C Vtref, M Vtref, and K Vtref, which are target values of output voltages from the toner density sensors, are stored. For the Y developing unit 7Y, the value of the output voltage from the toner density sensor 10Y is compared with the Y Vtref, and the Y toner supply device (not shown) is driven for a time corresponding to the comparison result. With this driving, an appropriate amount of Y toner is supplied to the Y developer whose Y toner density has been reduced by the consumption of Y toner accompanying development in the first agent storage portion 9Y. For this reason, the Y toner concentration of the Y developer in the second agent container 14Y is maintained within a predetermined range. Similar toner supply control is performed for the developers in the process units (1C, M, K) for other colors.

The Y toner image formed on the photoreceptor 3Y is intermediately transferred to an intermediate transfer belt described later. The drum cleaning device 4Y of the photoreceptor unit 2Y removes the toner remaining on the surface of the photoreceptor 3Y after the intermediate transfer process. As a result, the surface of the photoreceptor 3Y that has been subjected to the cleaning process is neutralized by a neutralizing device (not shown). By this charge removal, the surface of the photoreceptor 3Y is initialized and prepared for the next image formation. In FIG. 1 described above, in the process units 1C, M, and K for other colors, C, M, and K toner images are similarly formed on the photoreceptors 3C, M, and K, and the intermediate transfer belt is formed. Intermediate transfer.
An optical writing unit 20 is arranged below the process units 1Y, 1C, 1M, and 1K in the drawing. The optical writing unit 20 serving as a latent image forming unit irradiates the photoconductors 3Y, C, M, and K of the process units 1Y, C, M, and K with a laser beam L emitted based on the image information. Thereby, electrostatic latent images for Y, C, M, and K are formed on the photoreceptors 3Y, 3C, 3M, and 3K. The optical writing unit 20 deflects the laser light L emitted from the light source by the polygon mirror 21 that is rotationally driven by a motor, and passes through the photosensitive members 3Y, 3C, 3M, and 3K via a plurality of optical lenses and mirrors. Is irradiated. Instead of such a configuration, it is also possible to employ one that performs optical scanning with an LED array.

  A first paper feed cassette 31 and a second paper feed cassette 32 are disposed below the optical writing unit 20 so as to overlap in the vertical direction. In each of these paper feed cassettes, a plurality of recording papers P as recording members are accommodated in a stack of recording papers. The uppermost recording paper P includes a first paper feed roller 31a, The second paper feed rollers 32a are in contact with each other. When the first paper feed roller 31a is driven to rotate counterclockwise in the figure by a driving means (not shown), the uppermost recording paper P in the first paper feed cassette 31 is vertically oriented on the right side of the cassette in the figure. The paper is discharged toward the paper feed path 33 arranged so as to extend. Further, when the second paper feed roller 32 a is driven to rotate counterclockwise in the figure by a driving means (not shown), the uppermost recording paper P in the second paper feed cassette 32 is directed toward the paper feed path 33. Discharged. A plurality of transport roller pairs 34 are arranged in the paper feed path 33, and the recording paper P fed into the paper feed path 33 is sandwiched between the rollers of the transport roller pair 34 while being fed between the paper feed paths 33. 33 is conveyed from the lower side to the upper side in the figure.

A registration roller pair 35 is disposed at the end of the paper feed path 33. The registration roller pair 35 temporarily stops the rotation of both rollers as soon as the recording paper P fed from the conveyance roller pair 34 is sandwiched between the rollers. Then, the recording paper P is sent out toward a later-described secondary transfer nip at an appropriate timing.
Above each of the process units 1Y, 1C, 1M, and 1K, a transfer unit 40 that is endlessly moved counterclockwise in the drawing while an intermediate transfer belt 41 that is an endless moving body is stretched is disposed. The transfer unit 40 serving as transfer means includes an intermediate transfer belt 41, a belt cleaning unit 42, a first bracket 43, a second bracket 44, and the like. Further, four primary transfer rollers 45Y, 45C, 45M, 45K, a secondary transfer backup roller 46, a drive roller 47, an auxiliary roller 48, a tension roller 49, and the like are also provided. The intermediate transfer belt 41 is endlessly moved counterclockwise in the figure by the rotational driving of the driving roller 47 while being stretched by these eight rollers. The four primary transfer rollers 45Y, 45C, 45M, 45K each sandwich the intermediate transfer belt 41 moved endlessly in this manner from the photoreceptors 3Y, 3C, 3M, and 3K to form primary transfer nips. ing. Then, a transfer bias having a polarity opposite to that of the toner (for example, plus) is applied to the back surface (loop inner peripheral surface) of the intermediate transfer belt 41. The intermediate transfer belt 41 sequentially passes through the primary transfer nips for Y, C, M, and K along with its endless movement, and on the photoreceptor 3Y, C, M, and K on the front surface. The Y, C, M, and K toner images are superimposed and primarily transferred. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the intermediate transfer belt 41.

The secondary transfer backup roller 46 sandwiches the intermediate transfer belt 41 with the secondary transfer roller 50 disposed outside the loop of the intermediate transfer belt 41 to form a secondary transfer nip. The registration roller pair 35 described above feeds the recording paper P sandwiched between the rollers toward the secondary transfer nip at a timing at which the recording paper P can be synchronized with the four-color toner image on the intermediate transfer belt 41. The four-color toner image on the intermediate transfer belt 41 is affected by the secondary transfer electric field formed between the secondary transfer roller 50 to which the secondary transfer bias is applied and the secondary transfer backup roller 46, and the influence of the nip pressure. The secondary transfer is batch-transferred onto the recording paper P in the secondary transfer nip. Then, combined with the white color of the recording paper P, a full color toner image is obtained.
Untransferred toner that has not been transferred to the recording paper P adheres to the intermediate transfer belt 41 after passing through the secondary transfer nip. This is cleaned by the belt cleaning unit 42. In the belt cleaning unit 42, the cleaning blade 42a is brought into contact with the front surface of the intermediate transfer belt 41, whereby the transfer residual toner on the belt is scraped off and removed.

  The first bracket 43 of the transfer unit 40 swings at a predetermined rotation angle about the rotation axis of the auxiliary roller 48 as the solenoid (not shown) is turned on / off. When forming a monochrome image, the printer of the present image forming system rotates the first bracket 43 a little counterclockwise in the drawing by driving the solenoid described above. This rotation causes the Y, C, M primary transfer rollers 45Y, C, M to revolve counterclockwise in the drawing around the rotation axis of the auxiliary roller 48, thereby causing the intermediate transfer belt 41 to move in the Y, C direction. , M is separated from the photoconductors 3Y, 3C, 3M. Of the four process units 1Y, 1C, 1M, and 1K, only the K process unit 1K is driven to form a monochrome image. As a result, it is possible to avoid exhaustion of the process units due to wastefully driving the process units for Y, C, and M during monochrome image formation.

  A fixing unit 60 is disposed above the secondary transfer nip in the drawing. The fixing unit 60 includes a pressure heating roller 61 that includes a heat source such as a halogen lamp, and a fixing belt unit 62. The fixing belt unit 62 includes a fixing belt 64 as a fixing member, a heating roller 63 containing a heat source such as a halogen lamp, a tension roller 65, a driving roller 66, a temperature sensor (not shown), and the like. Then, the endless fixing belt 64 is endlessly moved in the counterclockwise direction in the drawing while being stretched by the heating roller 63, the tension roller 65, and the driving roller 66. In the process of endless movement, the fixing belt 64 is heated from the back side by the heating roller 63. A pressure heating roller 61 that is rotationally driven in the clockwise direction in the drawing is in contact with the surface of the fixing belt 64 that is heated in this manner from the front side. Thereby, a fixing nip where the pressure heating roller 61 and the fixing belt 64 abut is formed.

Outside the loop of the fixing belt 64, a temperature sensor (not shown) is disposed so as to face the front surface of the fixing belt 64 with a predetermined gap, and the fixing belt 64 just before entering the fixing nip. Detect surface temperature. This detection result is sent to a fixing power supply circuit (not shown). The fixing power supply circuit performs on / off control of power supply to the heat generation source included in the heating roller 63 and the heat generation source included in the pressure heating roller 61 based on the detection result of the temperature sensor. As a result, the surface temperature of the fixing belt 64 is maintained at about 140 [°].
In FIG. 1 described above, the recording paper P that has passed through the secondary transfer nip is separated from the intermediate transfer belt 41 and then sent into the fixing unit 60. Then, in the process of being conveyed from the lower side to the upper side in the figure while being sandwiched between the fixing nips in the fixing unit 60, the full-color toner image is fixed by being heated or pressed by the fixing belt 64.

The recording paper P subjected to the fixing process in this manner is discharged outside the apparatus after passing between the rollers of the paper discharge roller pair 67. A stack unit 68 is formed on the upper surface of the housing of the printer main body, and the recording paper P discharged to the outside by the discharge roller pair 67 is sequentially stacked on the stack unit 68.
Above the transfer unit 40, four toner cartridges 100 Y, C, M, and K that store Y, C, M, and K toners are disposed. The Y, C, M, and K toners in the toner cartridges 100Y, 100C, M, and K are appropriately supplied to the developing units 7Y, C, M, and K of the process units 1Y, C, M, and K. These toner cartridges 100Y, 100C, 100M, and 100K are detachable from the printer main body independently of the process units 1Y, 1C, 1M, and 1K.

Next, a characteristic configuration of the printer will be described.
FIG. 5 is a perspective view showing the Y charging device 5Y together with the Y photoconductor 3Y. FIG. 6 is an exploded perspective view showing the charging device 5Y. FIG. 7 is an enlarged configuration diagram showing the charging device 5Y together with the photoreceptor 3Y.
As shown in FIG. 5, the charging device 5Y disposed immediately below the photoreceptor 3Y includes a casing 501Y and a grid electrode 503Y. The grid electrode 503Y is made of a metal material such as stainless steel, copper, or iron in order to exhibit a function as an electrode. In addition to the role as an electrode, as shown in FIG. 6, it plays a role as a lid that covers a maintenance inspection opening provided in the casing 501Y. However, the inside of the casing 501Y is exposed through a plurality of slits 504Y as openings provided therein.
As shown in FIG. 7, the casing 501 </ b> Y is fixed in the printer main body so that the maintenance / inspection opening to which the grid electrode 503 </ b> Y is fixed faces the photoconductor 3 </ b> Y directly above. A ventilation opening 502Y is provided on the bottom plate facing downward in the vertical direction.
A charging brush 507Y is fixed in the casing 501Y. The charging brush 507Y has a metal holder 506Y as a conductive holding body, and a brush portion 505Y made of a plurality of conductive fibers (discharge electrodes) that are conductive fibers erected on the metal holder 506Y. Yes. The metal holder 506Y is fixed to the casing 501Y by being screwed to the casing 501Y. Examples of conductive fibers include petroleum pitch carbon fibers made from synthetic fibers such as acrylic, PAN-based carbon fibers made from coal tar, metal fibers made from stainless steel, and the like. Carbon fibers are advantageous in reducing manufacturing costs because they are cheaper and easier to obtain than metal fibers.

  As shown in FIG. 7, the slit 504Y of the grid electrode 503Y faces the tip of the conductive fiber of the charging brush 507Y fixed in the casing 501Y. In such a state, a charging bias having the same polarity (negative polarity in this example) as the uniform charging potential of the photoreceptor 3Y is applied to the metal holder 506Y of the charging brush 507Y by the charging power source 511Y. In addition, a grid bias having the same polarity as the uniform charging potential of the photoreceptor 3Y and having an absolute value smaller than the charging bias is applied to the grid electrode 503Y by the grid power source 510Y. Then, a discharge occurs between the tip of the conductive fiber of the charging brush 507Y and the photosensitive member 3Y as a latent image carrier through the slit 504Y of the grid electrode 503Y as an opening electrode, and the photosensitive member 3Y becomes negative. Uniform charging.

Next, a first example of a brush member in which conductive fibers are attached to a conductive holding body will be described with reference to FIGS. 8 to 11 and FIG. Conductive fibers (wax) are held at the ends of the conductive holder (a). The conductive fiber may be carbon fiber, or may be nylon, acrylic polyester, vinylon-containing fiber, or the like. The conductive fibers are arranged in a certain direction with equal density. The conductive holding body is not particularly limited as a material, and metals such as stainless steel (SUS), iron, copper, aluminum, molybdenum, and tartan, carbon fibers imparted with conductivity, ceramics, and phosphor bronze. It is made of an alloy.
In the normal brush, the fibers are arranged without any gaps (FIG. 8), but the electrodes of the proposed brush are arranged with a pitch, and the respective tips of the discharge electrode bundle are cut obliquely. (FIG. 9, FIG. 21). The length of the brush from the conductive support is equal to every electrode.
FIG. 10 is a diagram showing how the electrode portions of the brush are connected inside the conductive holding body. Adjacent electrodes are connected to each other, and the tip of the electrode section is gently “shaped”. A conductive holding body covers the brush electrode to form one brush (FIG. 10).
At this time, since the electrode part is cut diagonally, the shape of the cut is like a bamboo cut diagonally.
FIG. 12 shows a process for processing a braided brush. As a general processing method, a production method is adopted in which a knitted fiber bundle is sandwiched between holding bodies. In this method, the fiber bundle sandwiched between the holding bodies spreads toward the tip.

Next, a second example of a brush member in which conductive fibers are attached to a conductive holding body will be described with reference to FIGS. First, the form of the carbon fiber circulating in the world will be described. Since the diameter of the carbon fiber is very thin, about 6 μm, a plurality of carbon fibers are used in the world as a bundle. For example, 500 (or 1000/3000/6000/12000 ...) forms one bundle, and the shape of the bundle is flat and thin (FIG. 13).
Explain how to make this brush.
When this fiber is woven with a satin weave, a state shown in FIG. 14 is obtained, and a base fabric can be formed without breaking the shape of the flat fiber. The tip of the brush is formed by pulling out this base fabric with a Thomson type (FIG. 15). The base fabric from which the weft of the cut portion is removed is placed on the conductive holding body with a conductive adhesive or a conductive tape (FIG. 16).
Each electrode is in a state in which fibers are arranged thinly, and the tip is cut obliquely. The length of the brush from the conductive support is equal to every electrode.

  Next, a third example of a brush member in which conductive fibers are attached to a conductive holding body will be described with reference to FIG. The carbon fiber is attached to the cylindrical conductive member using a conductive adhesive or a conductive tape. The tip of the carbon fiber is cut obliquely using a cutter or the like. The cut surface of the carbon fiber has an elliptical shape. Each fiber is arranged in a cylindrical shape to form one electrode.

  Next, a fourth example of a brush member in which conductive fibers are attached to a conductive holding body will be described with reference to FIG. The carbon fiber is attached to the cylindrical conductive member using a conductive adhesive or a conductive tape. The tip of the carbon fiber is cut obliquely using a cutter or the like. The tip of the carbon fiber has a spiral shape. Each fiber is arranged in a cylindrical shape to form one electrode.

Next, the 5th example of the brush member by which the electroconductive fiber was attached to the electroconductive holding body is demonstrated using FIG. The carbon fiber is temporarily fixed to a metal plate such as SUS by using a conductive adhesive or a conductive tape, and then fixed by bending the metal plate. The tip of the carbon fiber is cut obliquely using a cutter or the like. Conductive grease may be applied between the metal plate and the carbon fiber.
The electrode unit configured as described above is attached to the conductive holding body. The conductive holding body is provided with mounting holes at an equal pitch, and the electrode unit is mounted by press-fitting into each hole. At this time, conductive grease may be applied between the electrode unit and the conductive holding body.

Next, a sixth example of a brush member in which conductive fibers are attached to a conductive holding body will be described with reference to FIGS. The carbon fiber is attached to the cylindrical conductive member using a conductive adhesive or a conductive tape. The tip of the carbon fiber is cut obliquely using a cutter or the like. The shape of the electrode tip of the electrode unit differs depending on the order of cutting and pasting, but it may be either as long as it is unified into one. Fig. 18 (A) shows the pasted cut fiber, and Fig. 18 (B) shows the cut cut after pasting.
The electrode unit configured as described above is attached to the conductive holding body. The conductive holder is provided with mounting holes at an equal pitch, and the electrode unit is mounted by press-fitting. At this time, conductive grease may be applied between the electrode unit and the conductive holding body.

Next, a seventh example of a brush member in which conductive fibers are attached to a conductive holder will be described with reference to FIG. Three electrodes constitute one unit. The carbon fiber is temporarily fixed to a metal plate such as SUS by using a conductive adhesive or a conductive tape, and then fixed by bending the metal plate. The tip of the carbon fiber is cut obliquely using a cutter or the like. Conductive grease may be applied between the metal plate and the carbon fiber.
The electrode unit configured as described above is attached to the conductive holding body. The conductive holding body is provided with mounting holes at an equal pitch, and the electrode unit is mounted by press-fitting into each hole. At this time, conductive grease may be applied between the electrode unit and the conductive holding body.

FIG. 1 is a schematic cross-sectional view showing an embodiment of an image forming apparatus according to the present invention. FIG. 2 is an explanatory view showing a combination of the photosensitive unit and the developing unit. FIG. 3 is a perspective view showing the process unit. FIG. 4 is a perspective view showing the developing unit. FIG. 5 is a perspective view showing the charging device together with the photosensitive member. FIG. 6 is an exploded perspective view showing the charging device. FIG. 7 is an explanatory diagram showing the structure of the charging device. FIG. 8 is an explanatory view showing a brush member in which conductive fibers are attached to a conventional ordinary conductive holding body. FIG. 9 is an explanatory view showing a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. FIG. 10 is an explanatory diagram relating to the brush member according to the present invention in which conductive fibers are attached to the conductive holding body of the present invention. FIG. 11 is an explanatory diagram relating to a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. FIG. 12 is an explanatory diagram showing a processing step for a braided brush. FIG. 13 is an explanatory diagram relating to a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. FIG. 14 is an explanatory view of a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. FIG. 15 is an explanatory view of a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. FIG. 16 is an explanatory view of a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. FIG. 17 is an explanatory view of a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. FIG. 18 is an explanatory diagram relating to a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. Fig. 18 (A) shows the cut fiber that is pasted, and Fig. 18 (B) shows the cut fiber after it has been pasted. FIG. 19 is an explanatory view of a brush member according to the present invention in which conductive fibers are attached to a conductive holding body. FIG. 20 is an explanatory diagram showing equipotential lines in the brush member. FIG. 21 is an explanatory diagram relating to a brush member according to the present invention in which conductive fibers are attached to a conductive holding body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Process unit 2 Photoconductor unit 3 Photoconductor 4 Dry cleaning apparatus 5 Charging apparatus 7 Developing unit 8 1st conveyance screw 9 1st agent accommodating part 10 Toner density sensor 11 2nd conveyance screw 12 Developing roll 13 Doctor blade 14 2nd agent Housing 15 Development sleeve 16 Magnet roller 20 Optical writing unit 21 Polygon mirror 31 First paper feed cassette 31a First paper feed roller 32 Second paper feed cassette 32a Second paper feed roller 33 Paper feed path 34 Conveying roller pair 35 Resist Roller pair 40 Transfer unit 41 Intermediate transfer belt 42 Belt cleaning unit 42a Cleaning blade 43 First bracket 44 Second bracket 45 Primary transfer roller 46 Secondary transfer backup roller 47 Drive roller 48 Auxiliary roller 49 50 Roller 50 Secondary transfer roller 60 Fixing unit 61 Pressure heating roller 62 Fixing belt unit 63 Heating roller 64 Fixing belt 65 Tension roller 66 Driving roller 67 Paper discharge roller pair 68 Stack unit 100 Toner cartridge 501 Casing 502 Ventilation opening 503 Grid Electrode 504 Slit 505 Brush part 506 Metal holder 507 Charging brush 510 Grid power supply 511 Charging power supply L Laser light P Recording paper

Claims (7)

A conductive holding body and a discharge electrode held by the conductive holding body, and causing discharge through a gap between the tip or surface of the discharge electrode to which a charging bias is applied and the latent image carrier of the image forming apparatus. A charging device for uniformly charging the surface of the latent image carrier,
Discharging between the discharge electrode and the latent image carrier via an electrode having a plurality of openings facing the tip or surface of the discharge electrode and to which a bias having a value different from the charging bias is applied. In the charging device to be generated,
The discharge electrodes are arranged in a brush shape while forming a bundle, the tips of the discharge electrode bundle are cut obliquely, and the tips of the discharge electrode bundle are arranged with a pitch. A charging device. The charging device according to claim 1,
A charging device, wherein discharge electrodes are arranged in a line to form an electrode bundle. The charging device according to claim 1,
A charging device, wherein the discharge electrode has a cylindrical shape. The charging device according to claim 3,
A charging device, wherein the electrode tip is arranged in a spiral shape. The charging device according to any one of claims 1 to 4,
A charging device characterized in that an electrode and a conductive holder are detachable. The charging device according to any one of claims 1 to 4,
A charging device comprising a plurality of electrodes as one electrode unit. An image forming apparatus comprising the charging device according to claim 1.

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