JP6011839B2 - Bearing, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a bearing that rotatably holds a shaft portion of a rotating member, and a copying machine, a printer, a facsimile, or a complex machine thereof, and is detachably installed therein. Process cartridge.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, an electrode plate (electrode) is slidably brought into contact with an end surface of a shaft portion of a rotating member such as a charging roller, and the charging roller from the image forming apparatus main body side through the electrode plate There is known a technique for applying a predetermined charging bias to (see, for example, Patent Document 1).

  Specifically, in Patent Document 1 and the like, the charging roller is disposed so that the shaft portion thereof is rotatably supported by a bearing and is in contact with (or is not contacted with) a photosensitive drum as an image carrier. ing. In addition, the electrode plate is installed so that the tip of the electrode plate comes into pressure contact with the end surface of the shaft portion of the charging roller with a predetermined pressure. A predetermined voltage (charging bias) is applied to the charging roller from the power supply unit of the image forming apparatus main body via the electrode plate, so that the surface of the photosensitive drum is charged by the charging roller.

  The conventional technology has a problem in that shaving powder is generated from the electrode plate that is in sliding contact with the end surface of the shaft portion of the charging roller due to the rotation of the charging roller. If such shaving powder falls down and adheres to the photosensitive drum (image carrier), an abnormal image may be generated in the toner image formed on the photosensitive drum. It was.

Such a problem is not particularly negligible in a high-speed machine in which the charging roller is rotated at a high speed because the sliding resistance between the shaft portion and the electrode plate increases.
Such a problem is not limited to the case where the electrode plate is slidably contacted with the end face of the shaft portion of the charging roller, but is common when the slidable contact member is slidably contacted with the shaft portion of various rotating members. Can happen.

  This invention was made in order to solve the problems as described above, and by causing the sliding contact member to slide in contact with the shaft portion of the rotating member, even if shaving powder or the like is generated from the sliding contact member or the shaft portion, It is an object of the present invention to provide a bearing, a process cartridge, and an image forming apparatus that are less likely to cause a problem of adhering to a lower member.

The bearing according to the first aspect of the present invention is a bearing in which the shaft portion of the rotating member is rotatably held, and the end surface of the shaft portion is directed toward a space below the position where the sliding contact member is in sliding contact . And a tray portion that collects falling objects that fall at that position.

  In the present application, the “process cartridge” refers to a charging unit that charges the image carrier, a developing unit (developing device) that develops a latent image formed on the image carrier, and a cleaning on the image carrier. It is defined that at least one of the cleaning units and the image carrier are a unit that is integrated and detachably installed on the main body of the image forming apparatus.

  In the bearing in which the shaft portion of the rotating member is rotatably held, the present invention projects toward a space below the position where the sliding contact member is slidably contacted with the shaft portion, and collects falling objects falling to that position. A saucer is provided. Thereby, even if shaving powder or the like is generated from the sliding contact member or the shaft portion by causing the sliding contact member to be in sliding contact with the shaft portion of the rotating member, the bearing or process is less likely to cause a problem that it adheres to the lower member. A cartridge and an image forming apparatus can be provided.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is a block diagram which shows an image creation part. It is a schematic perspective view which shows a process cartridge. It is a schematic side view showing an internal configuration of a process cartridge. It is a perspective view which shows a part of structure inside a process cartridge. It is a front view which shows a part of internal structure of a process cartridge. FIG. 3 is a perspective view showing the vicinity of a main body electrode plate of the image forming apparatus main body. It is a schematic side view which shows the state in which an electrode plate is connected to a main body electrode plate. It is a schematic perspective view which shows the vicinity of the bearing of another form. It is a schematic perspective view which shows the vicinity of the bearing of another form.

Embodiment.
Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an apparatus main body of a tandem color copier as an image forming apparatus, 2 a writing unit that emits laser light based on input image information, and 3 an original conveying unit that conveys an original D to an original reading unit 4. 4 is a document reading unit that reads image information of the document D, 7 is a paper feeding unit that accommodates a recording medium P such as transfer paper, 9 is a registration roller (timing roller) that adjusts the conveyance timing of the recording medium P, and 11Y. , 11M, 11C, and 11BK are photosensitive drums as image carriers on which toner images of respective colors (yellow, magenta, cyan, and black) are formed, and 12 is charged on the photosensitive drums 11Y, 11M, 11C, and 11BK. A charging roller (charging unit) 13 is a developing device for developing an electrostatic latent image formed on each of the photosensitive drums 11Y, 11M, 11C, and 11BK, and 14 is a photosensitive drum 11. Shows 11M, 11C, transfer bias roller for transferring superimposed on the recording medium P the toner image formed on 11BK (1 primary transfer bias roller), 15 the process cartridge (detachable unit), a.

  Reference numeral 17 denotes an intermediate transfer belt onto which toner images of a plurality of colors are transferred, 18 denotes a secondary transfer bias roller for transferring the color toner image on the intermediate transfer belt 17 onto the recording medium P, and 19 denotes an intermediate transfer. An intermediate transfer belt cleaning unit for cleaning the belt 17 and a fixing device 20 for fixing an unfixed image on the recording medium P are shown.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described. Note that FIG. 2 can also be referred to for the image forming process performed on the photosensitive drums 11Y, 11M, 11C, and 11BK.
First, the document D is transported from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 3 and placed on the contact glass 5 of the document reading unit 4. Then, the document reading unit 4 optically reads the image information of the document D placed on the contact glass 5.

  Specifically, the document reading unit 4 scans the image of the document D on the contact glass 5 while irradiating light emitted from an illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. The writing unit 2 emits laser light L (see FIG. 2) based on the image information of each color toward the corresponding photosensitive drums 11Y, 11M, 11C, and 11BK.

On the other hand, the four photosensitive drums 11Y, 11M, 11C, and 11BK are rotated counterclockwise in FIG. First, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK are uniformly charged at a portion facing the charging roller 12 (rotating member) (a charging process). Thus, a charged potential is formed on the photosensitive drums 11Y, 11M, 11C, and 11BK. Thereafter, the charged surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK reach the irradiation positions of the respective laser beams.
In the writing unit 2, laser light corresponding to the image signal is emitted from the four light sources corresponding to each color. Each laser beam passes through a separate optical path for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

  Laser light corresponding to the yellow component is irradiated on the surface of the first photosensitive drum 11Y from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 11Y by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 11Y after being charged by the charging roller 12.

  Similarly, the laser beam corresponding to the magenta component is irradiated onto the surface of the second photosensitive drum 11M from the left side of the paper, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light is applied to the surface of the third photosensitive drum 11C from the left side of the paper, and an electrostatic latent image of the cyan component is formed. The black component laser beam is applied to the surface of the fourth photosensitive drum 11BK from the left side of the paper, and an electrostatic latent image of the black component is formed.

Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK on which the electrostatic latent images of the respective colors are formed reach positions facing the developing device 13, respectively. Then, the respective color toners are supplied from the developing devices 13 onto the photosensitive drums 11Y, 11M, 11C, and 11BK, and the latent images on the photosensitive drums 11Y, 11M, 11C, and 11BK are developed (development process). .)
Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK after the development process reach the facing portions of the intermediate transfer belt 17, respectively. Here, a transfer bias roller 14 is installed at each facing portion so as to contact the inner peripheral surface of the intermediate transfer belt 17. Then, the toner images of the respective colors formed on the photosensitive drums 11Y, 11M, 11C, and 11BK are sequentially superimposed and transferred onto the intermediate transfer belt 17 at the position of the transfer bias roller 14 (in the primary transfer process). is there.).

Then, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK after the transfer process reach positions facing the cleaning blade 15a (cleaning unit), respectively. Then, the untransferred toner remaining on the photosensitive drums 11Y, 11M, 11C, and 11BK is collected by the cleaning blade 15a (this is a cleaning process).
Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK pass through a neutralization unit (not shown), and a series of image forming processes on the photoconductive drums 11Y, 11M, 11C, and 11BK is completed.

On the other hand, the intermediate transfer belt 17 on which the toners of the respective colors on the photosensitive drums 11Y, 11M, 11C, and 11BK are transferred (carrying) are run in the clockwise direction in the drawing and are connected to the secondary transfer bias roller 18. Reach the opposite position. Then, a color toner image carried on the intermediate transfer belt 17 is transferred onto the recording medium P at a position facing the secondary transfer bias roller 18 (secondary transfer step).
Thereafter, the surface of the intermediate transfer belt 17 reaches the position of the intermediate transfer belt cleaning unit 19. Then, the untransferred toner adhered on the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit 19, and a series of transfer processes in the intermediate transfer belt 17 is completed.

Here, the recording medium P transported between the intermediate transfer belt 17 and the secondary transfer bias roller 18 (secondary transfer nip) is transported from the paper supply unit 7 via the registration roller 9 and the like. It is a thing.
Specifically, the recording medium P fed by the paper feeding roller 8 from the paper feeding unit 7 that stores the recording medium P is guided to the registration roller 9 after passing through the conveyance guide. The recording medium P that has reached the registration roller 9 is conveyed toward the secondary transfer nip at the same timing.

Then, the recording medium P on which the full-color image is transferred is guided to the fixing device 20 by the transport belt. In the fixing device 20, the color image is fixed on the recording medium P at the nip between the fixing belt and the pressure roller.
Then, the recording medium P after the fixing step is discharged as an output image outside the apparatus main body 1 by the discharge roller, and a series of image forming processes is completed.

Next, the image forming unit of the image forming apparatus will be described in detail with reference to FIG.
As shown in FIG. 2, the image forming unit includes a photosensitive drum 11 as an image carrier, a charging roller 12 as a rotating member that charges the photosensitive drum 11, and an electrostatic latent image formed on the photosensitive drum 11. A developing device 13 (developing unit) that develops toner, a cleaning blade 15a (cleaning unit) that collects untransferred toner on the photosensitive drum 11, and a lubricant supply device 16 (lubricant) that supplies lubricant to the photosensitive drum 11 And a cleaning roller 21 for cleaning the charging roller 12, and the like.
In the present embodiment, among the constituent members of the image forming unit, the photosensitive drum 11, the charging roller 12, the cleaning blade 15 a (cleaning unit), the lubricant supply device 16, and the cleaning roller 21 are used as the process cartridge 15. It is integrated and configured to be detachable from the apparatus main body 1 as a process cartridge 15 (detachable unit). Further, the developing device 13 is configured to be detachable from the apparatus main body 1 as a unit different from the process cartridge 15.
Since the image forming sections (or process cartridges) of the respective colors have almost the same structure, the image forming sections and process cartridges in FIGS. 2 to 9 exclude the alphabets (Y, C, M, BK). And illustrated.
Further, the process cartridge 15 generally has an appearance as shown in FIG.

Here, the photoconductor drum 11 as an image carrier is a negatively chargeable organic photoconductor, which is a constituent member provided with a photosensitive layer or the like on a drum-like conductive support.
Although not shown, the photosensitive drum 11 has an undercoat layer that is an insulating layer, a charge generation layer and a charge transport layer as a photosensitive layer, and a protective layer (surface layer) in this order on a conductive support as a base layer. Are stacked.
As the conductive support (base layer) of the photosensitive drum 11, a conductive material having a volume resistance of 10 ¹⁰ Ωcm or less can be used.

The charging roller 12 as a rotating member is a roller member formed by covering an outer periphery of a shaft portion 12 a (conductive cored bar) with a medium-resistance elastic layer. It is arranged so as to face the photosensitive drum 11 with a small gap on the downstream side in the rotation direction. In the present embodiment, the charging roller 12 is urged toward the photosensitive drum 11 by a spring 24 (biasing member) via a bearing 22 (charging roller bearing portion 22a) and is inserted into the shaft portion 12a. The roller 25 provided is in contact with the photosensitive drum 11 to face the photosensitive drum 11 with a small gap (see FIG. 4). Also, the charging roller 12 is in pressure contact with a cleaning roller 21 held by a bearing 22 (cleaning roller bearing portion 22b) so as to be movable in the direction of gravity (see FIG. 4).
A predetermined voltage (charging bias) is applied to the charging roller 12 via a main body electrode plate 110 and an electrode plate 30 (sliding contact member) from a power supply unit (not shown) installed in the apparatus main body 1. To uniformly charge the surface of the opposing photosensitive drum 11.
In the present embodiment, the charging roller 12 is opposed to the photosensitive drum 11 in a non-contact manner with a small gap, but the charging roller 12 may be brought into contact with the photosensitive drum 11.

The developing device 13 is disposed such that the developing roller 13a is in contact with the photosensitive drum 11, and a developing region (developing nip portion) is formed between both members. In the developing device 13, toner T (one-component developer) is accommodated. The developing device 13 develops the electrostatic latent image formed on the photosensitive drum 11 (forms a toner image).
Specifically, referring to FIG. 2, the developing device 13 in the present embodiment is a one-component developing type developing device, and includes a developing roller 13a (developer carrier), a supply roller 13b, and a thinning member. Doctor blade 13c, stirring member 13d, and the like.

The developing device 13 configured as described above operates as follows.
First, a part of the toner supplied and stored in the developing device 13 is carried on the supply roller 13b. The toner carried on the supply roller 13b is frictionally charged at the pressure contact portion with the developing roller 13a, and then moved and carried on the developing roller 13a. Thereafter, the toner carried on the developing roller 13a reaches the contact position (development region) with the photosensitive drum 11 after being thinned and uniformized at the position of the doctor blade 13c. At this position, toner is attracted to the latent image formed on the photosensitive drum 11 by an electric field (developing electric field) formed in the developing region.

  In the present embodiment, spherical toner having a circularity of 0.98 or more is used as the toner T in order to improve the image quality. The “circularity” is an average circularity measured by a flow type particle image analyzer “FPIA-2000” (manufactured by Toa Medical Electronics Co., Ltd.). Specifically, 0.1 to 0.5 ml of a surfactant (preferably an alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of water from which impure solids have been removed in advance. Further, about 0.1 to 0.5 g of a measurement sample (toner) is added. Thereafter, the suspension in which the toner is dispersed is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the dispersion liquid concentration is set to 3000 to 10000 / μl in the above-described analyzer. Then, the shape and distribution of the toner are measured.

As the spherical toner, it is possible to use an irregularly shaped toner (pulverized toner) whose shape is distorted by a pulverization method that has been widely used so far, which is spheroidized by heat treatment or the like, or a toner manufactured by a polymerization method. it can.
When such a spherical toner is used, conventionally, there is a case in which a slight gap between the cleaning blade 15a and the photosensitive drum 11 enters the gap and eventually passes through the gap, resulting in poor cleaning. However, in the present embodiment, a lubricant is applied to the surface of the photosensitive drum 11 by the lubricant supply device 16 to improve the toner peelability (removability) on the photosensitive drum 11, so that a cleaning failure occurs. Is suppressed.

The cleaning blade 15 a is disposed on the downstream side in the rotation direction of the photosensitive drum 11 with respect to the lubricant supply device 16. The cleaning blade 15a is made of a rubber material such as urethane rubber, and is in contact with the surface of the photosensitive drum 11 at a predetermined angle and a predetermined pressure. As a result, deposits such as untransferred toner adhering to the photosensitive drum 11 are mechanically scraped and collected in the process cartridge 15. Then, the toner collected in the process cartridge 15 is conveyed as a waste toner toward a waste toner collection container (not shown) by the conveyance coil 15b. Here, examples of the deposit that adheres to the photosensitive drum 11 include untransferred toner, paper dust generated from the recording medium P (paper), and a discharge product generated on the photosensitive drum 11 when discharged by the charging roller 12a. And additives added to the toner.
In addition, the cleaning blade 15a in the present embodiment also functions as a thinning blade that thins the lubricant supplied onto the photosensitive drum 11 by the lubricant supply roller 16a.

The lubricant supply device 16 includes a solid lubricant 16b, a lubricant supply roller 16a (brush roller) that is in sliding contact with the photosensitive drum 11 and the solid lubricant 16b, a holding member 16e that holds the solid lubricant 16b, and a solid lubricant. 16b and a compression spring 16c as an urging means for urging the holding member 16e toward the lubricant supply roller 16a.
The lubricant is supplied onto the photosensitive drum 11 by the lubricant supply device 16 configured as described above. Then, the lubricant supplied onto the photosensitive drum 11 is thinned by the cleaning blade 15 a disposed on the downstream side of the lubricant supply device 16.

Here, as for the lubricant supply roller 16a (brush-shaped roller), brush hair having a length (hair foot) in the range of 0.2 to 20 mm (preferably 0.5 to 10 mm) was planted on the base fabric. An object is wound around a metal core in a spiral shape.
When the length of the bristle exceeds 20 mm, the bristle falls in a predetermined direction due to repeated rubbing with the photosensitive drum 11 over time, and the scraping property of the solid lubricant 16b or from the photosensitive drum 11 is reduced. Toner removability is reduced. On the other hand, if the length of the bristle is less than 0.2 mm, the physical contact force with respect to the solid lubricant 16b and the photosensitive drum 11 is insufficient. Therefore, it is preferable that the length of the bristle is in the above range.

The lubricant supply roller 16a rotates so as to come into contact with the photosensitive drum 11 that rotates counterclockwise in FIG. 2 in the counter direction (counterclockwise rotation in FIG. 2). The lubricant supply roller 16a (brush bristles) is disposed so as to be in sliding contact with the solid lubricant 16b and the photosensitive drum 11, and the lubricant supply roller 16a rotates to rotate the lubricant from the solid lubricant 16b. After the scraped lubricant is conveyed to the sliding contact position with the photosensitive drum 11, the lubricant is applied onto the photosensitive drum 11.
A compression spring 16c is disposed behind the solid lubricant 16b in order to eliminate uneven contact between the lubricant supply roller 16a and the solid lubricant 16b, and is held (adhered) to the holding member 16e. The solid lubricant 16b is urged toward the lubricant supply roller 16a.

In the present embodiment, the solid lubricant 16b is mainly formed of zinc stearate. Specifically, the solid lubricant 16b is preferably prepared by dissolving a lubricating oil additive mainly composed of zinc stearate, having no side effects due to overcoating, and having sufficient lubricity.
Zinc stearate is a typical lamellar crystal powder. A lamellar crystal has a layered structure in which amphiphilic molecules are self-organized, and when a shearing force is applied, the crystal breaks along the layers and is slippery. Therefore, the surface of the photosensitive drum 11 can be made to have low friction. In other words, the surface of the photosensitive drum 11 can be effectively covered with a small amount of lubricant by the lamellar crystals that receive the shearing force and uniformly cover the surface of the photosensitive drum 11.

  As the solid lubricant 16b, in addition to zinc stearate, stearic acid groups such as barium stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, etc. The thing which has can be used. In addition, the same fatty acid group zinc oleate, barium oleate, lead oleate, the same compound as stearic acid, zinc palmitate, barium palmitate, lead palmitate, the following compound similar to stearic acid May be used. In addition, caprylic acid, linolenic acid, corinolenic acid and the like can be used as the fatty acid group. In addition, waxes such as candelilla wax, canrunauba wax, rice wax, wax, coconut oil, beeswax, and lanolin can also be used. These easily become organic solid lubricants and have good compatibility with the toner.

When the solid lubricant 16b is applied to the surface of the photosensitive drum 11 via the lubricant supply roller 16a, a powdery lubricant is applied to the surface of the photosensitive drum 11, but the lubricity is sufficient in this state. Therefore, the cleaning blade 15a also functions as a thinned blade that makes the lubricant uniform. The cleaning blade 15a forms a film of the lubricant on the photosensitive drum 11, and the lubricant exhibits its lubricity sufficiently.
At this time, the finer the powdery lubricant applied by the lubricant supply roller 16a, the thinner the thin film on the photosensitive drum 11 at the molecular film level by the cleaning blade 15a.

Hereinafter, the configuration and operation of the process cartridge 15 and the image forming apparatus 1 which are characteristic in the present embodiment will be described in detail with reference to FIGS.
As described above, the process cartridge 15 is detachably installed on the image forming apparatus main body 1. Specifically, in the apparatus main body 1 of FIG. 1, the process cartridges 15 of the respective colors are respectively mounted in the + X direction (or detached in the −X direction) with a main body cover (not shown) being opened. become.).
Although illustration is omitted, the process cartridge 15 is mounted along the guide rail of the apparatus main body 1, and the position in the apparatus main body 1 is determined. Then, as the process cartridge 15 is mounted on the apparatus main body 1, an electrode plate 30 (also referred to FIGS. 3 to 5) as a sliding contact member installed on the process cartridge 15 is shown in FIG. In addition, the image forming apparatus main body 1 is electrically connected to the main body electrode plate 110 (see FIG. 7 as well) to which a voltage is applied.

As shown in FIGS. 4 and 5, the electrode plate 30 (sliding contact member) is electrically connected to a charging roller 12 as a rotating member constituting the process cartridge 15. Specifically, the electrode plate 30 (sliding contact member) is disposed so as to be in sliding contact (contact) with the end surface of the shaft portion 12a on one end side (the right side in FIG. 4) of the charging roller 12 (rotating member). ing.
The electrode plate 30 is obtained by bending a plate-like metal material having spring properties such as stainless steel. The plate thickness of the electrode plate 30 is preferably about 0.05 to 0.2 mm, and is set to 0.1 mm in the present embodiment. The electrode plate 30 is pressed against the inner wall surface by a compression spring 24 as an urging member while being held along the inner wall surface of the side cover 15d (see FIG. 3) of the process cartridge 15. It is held fixed. Referring to FIG. 3, the side cover 15 d is installed so as to cover the side of the case 15 c that functions as the main housing of the process cartridge 15.

More specifically, as shown in FIG. 5, a first contact portion 30a, a second contact portion 30b, and the like are formed on the electrode plate 30 as a sliding contact member by bending.
The first contact portion 30a of the electrode plate 30 is in contact with the main body electrode plate 110 of the apparatus main body 1 while being elastically deformed in a predetermined direction (in the direction of the arrow in FIG. 8B). Specifically, as shown in FIG. 3, the side cover 15d of the process cartridge 15 is formed with an opening 15d1 through which the first contact portion 30a of the electrode plate 30 is exposed. When the process cartridge 15 shown in FIG. 3 is mounted in the + X direction on the apparatus main body 1, the first contact portion 30a of the electrode plate 30 exposed from the opening 15d1 is installed on the main body side plate installed on the back side in the mounting direction. The main body electrode plate 110 (refer to FIG. 7) held by the holding portion 100a of 100 is brought into contact. At this time, as shown in FIGS. 8A to 8B, when the first contact portion 30a comes into contact with the main body electrode plate 110 in accordance with the mounting operation of the process cartridge 15, the main body electrode plate 110 causes the first contact. The portion 30a is pushed and elastically deformed in the direction of the arrow in FIG. As described above, the first contact portion 30a is elastically deformed to come into contact with the main body electrode plate 110, so that both the electrodes 30, 110 can be reliably connected to each other, and the contact between the both electrodes 30, 110 can be ensured. This prevents a problem that prevents the process cartridge 15 from being mounted.

Here, in the present embodiment, main body electrode plate 110 is a relatively rigid rod-shaped member made of a metal material (sheet metal) such as stainless steel having a plate thickness of about 0.5 mm. The main body electrode plate 110 is connected to a power supply unit (not shown) in the apparatus main body 1 and is supplied with a predetermined voltage (charging bias). Further, as shown in FIGS. 4 and 5, the second contact portion 30 b of the electrode plate 30 contacts the end surface of the shaft portion 12 a of the charging roller 12 rotatably held by the bearing 22 (charging roller bearing portion 22 a). The electrode plate 30 is electrically connected to the charging roller 12. With such a configuration, a predetermined voltage (charging bias) is applied to the charging roller 12 of the process cartridge 15 mounted on the apparatus body 1 from the apparatus body 1 side via the body electrode plate 110 and the electrode plate 30. Will be.
In the present embodiment, the bearing 22 (charging roller bearing portion 22a) is formed of a conductive resin material, and the compression spring 24 is formed of a conductive metal material. Therefore, the charging roller 12 of the process cartridge 15 attached to the apparatus main body 1 is different from the above-described path through the main body electrode plate 110, the electrode plate 30, the compression spring 24, and the bearing 22 from the apparatus main body 1 side. A charging bias is also applied to the path. Thereby, even if a contact failure occurs between the second contact portion 30b and the shaft portion 12a, it is possible to prevent a problem that the charging bias is not applied to the charging roller 12.

Further, referring to FIG. 4, along with the mounting operation of process cartridge 15 to apparatus main body 1, the inner peripheral portion of the flange on the back side (one end side in the rotation axis direction) of photosensitive drum 11 of process cartridge 15 is mounted. The coupling 11 a as a drive transmission portion formed in the above is fitted into the main body side coupling 115 installed on the main body side plate 100.
The coupling 11a is formed so as to be exposed to the outside (on the main body coupling 115 side of the apparatus main body 1) from the opening (not shown) of the side cover 15d shown in FIG. . In the coupling 11a, a plurality of claw portions arranged at intervals in the rotation direction are formed so as to protrude in the + X direction.
Although not shown, a drive motor having a main body side coupling 115 installed on the motor shaft is fixed to the main body side plate 100 of the apparatus main body 1. Further, the main body side coupling 115 is formed with a plurality of claw portions arranged at intervals in the rotation direction so as to protrude in the −X direction, and these claw portions are coupled to the coupling 11 a of the photosensitive drum 11. The drive is transmitted by meshing with the claws.

  Then, with the coupling 11a (drive transmission unit) and the main body coupling 115 engaged with each other as described above, the photosensitive drum 11 (through the main body coupling 115 and the coupling 11a from the driving motor of the image forming apparatus main body 1 is connected. Driving force is transmitted to the image carrier, and the photosensitive drum 11 rotates in a predetermined direction (counterclockwise in FIG. 2). Further, the driving force is transmitted from the photosensitive drum 11 to the charging roller 12, the conveying screw 15b, and the lubricant supply roller 16a as a plurality of driven rotating bodies, and the driven rotating bodies 12, 15b and 16a are respectively in predetermined directions. It will be driven and rotated.

Specifically, referring to FIG. 4, helical gears 11b and 11c are installed at both ends in the rotation axis direction of the photosensitive drum 11 as an image carrier.
Specifically, a first helical gear 11b is formed on the outer peripheral portion and a coupling 11a is formed on the inner peripheral portion on one end side of the cylindrical (drum-shaped) drum main portion on which the photosensitive layer and the like are formed. The flange is press-fit. Further, a flange having a second helical gear 11c formed on the outer peripheral portion is press-fitted and bonded to the other end side of the drum main portion.
On the other hand, a helical gear 12b (charging roller helical gear) that meshes with the second helical gear 11c of the photosensitive drum 11 is provided on the shaft portion on the other end side of the charging roller 12. Although not shown, a helical gear (a helical gear for the lubricant supply roller) that meshes with the first helical gear 11b of the photosensitive drum 11 is installed on the shaft portion on one end side of the lubricant supply roller 16a. Yes. Further, although not shown in the drawing, a helical gear (carrying screw helical gear) that meshes with the lubricant supply roller helical gear is installed on the shaft portion on one end side of the conveying screw 15b.

  With such a configuration, when a driving force is transmitted from the driving motor 116 of the image forming apparatus main body 1 to the photosensitive drum 11 via the main body coupling 115 and the coupling 11a, the second helical gear 11c is transferred from the photosensitive drum 11. Then, the driving force is transmitted to the charging roller 12 via the charging roller helical gear 12b, and the driving force is transmitted from the photosensitive drum 11 to the lubricant supplying roller 16a via the first helical gear 11b and the lubricant supplying roller helical gear. Further, the driving force is transmitted to the conveying screw 15b through the lubricant supply roller helical gear and the conveying screw helical gear. Then, each driven rotor 12, 15b, 16a rotates in a predetermined direction.

Here, in the present embodiment, the direction in which the charging roller 12 thrust moves in the direction of the rotation axis by the force acting on the helical gear 12b (charging roller helical gear) installed on the charging roller 12 is a direction away from one end side ( (It is the -X direction in FIG. 3). Specifically, the helical surface of the charging roller helical gear 12b is set so that the torsion direction of the charging roller helical gear 12b is leftward, and the tooth surface of the charging roller helical gear 12b receives the driving force transmitted from the photosensitive drum 11 to the charging roller 12. Then, the reaction force does not act in the + X direction depending on the inclination direction of the tooth surface, but acts in the −X direction.
As described above, when the driving of the process cartridge 15 is started, the charging roller 12 performs a thrust movement in the −X direction (in the direction of the white arrow in FIG. 3), and thus the shaft portion 12a on the + X direction side. The problem that the contact pressure of the electrode plate 30 (second contact portion 30b) in contact with the electrode plate becomes too strong and the electrode plate 30 and the shaft portion 12a are shaved can be reduced.
A force is also applied to the charging roller helical gear 12b in the + Z direction by drive transmission, but the spring force of the compression spring 24 is sufficiently applied in the -Z direction. The desired gap with the body drum 11 is maintained.

  Here, referring to FIGS. 4 to 6, in the present embodiment, bearing 22 on one end side that rotatably holds shaft portion 12 a of charging roller 12 (bearing 22 installed on the right side in FIG. 4). .) Is integrally formed with a charging roller bearing 22a, a cleaning roller bearing 22b, a tray 22c, and the like. Further, a charging roller bearing portion, a cleaning roller bearing portion, and the like are also provided on the other end side bearing 23 (the bearing 22 installed on the left side in FIG. 4) that rotatably holds the shaft portion 12a of the charging roller 12. It is integrally formed. The bearing 23 on the other end side is configured in substantially the same manner as the bearing 22 on the one end side, except that the tray portion 22c is not installed and formed symmetrically. Description is omitted.

  The charging roller bearing portion 22 a of the bearing 22 is a portion in which a hole portion into which the shaft portion 12 a of the charging roller 12 is inserted is formed and functions as a sliding bearing of the charging roller 12. A groove portion is formed on the side of the charging roller bearing portion 22a, and the groove portion is fitted to a convex rail portion (not shown) formed on the inner wall surface of the cover 15c of the process cartridge 15. In the process cartridge 15, the bearing 22 (charging roller 12) is held so as to be slidable toward the photosensitive drum 11. The bearing 22 (charging roller 12) is urged toward the photosensitive drum 11 by the spring force of the compression spring 24, and the roller 25 (outer diameter of the charging roller 12) inserted into the shaft portion 12 a of the charging roller 12. Is formed so as to have a slightly larger outer diameter.) By contacting the photosensitive drum 11, the charging roller 12 is installed with a desired minute gap with respect to the photosensitive drum 11. Become. As described above, the charging roller 12 is rotated in the clockwise direction in FIG. 2 by the drive transmission from the photosensitive drum 11 to the helical gear 12b.

The cleaning roller bearing portion 22b of the bearing 22 is formed with an elongated hole portion (formed so that the longitudinal direction is a vertical direction) into which the shaft portion of the cleaning roller 21 is inserted, and the cleaning roller 21 has its own weight. This part functions as a bearing that contacts the charging roller 12 and rotates the cleaning roller 21 by frictional resistance in conjunction with the rotation of the charging roller 12. With such a configuration, a member such as a gear for driving the cleaning roller 21 is not required, so that the process cartridge 15 can be reduced in cost and size.
The cleaning roller 21 is a roller member in which an elastic foam layer made of a melamine resin foam or the like is formed on a shaft portion (core metal), and is for cleaning the surface of the charging roller 12.

4 to 6, the tray 22c of the bearing 22 is directed toward a space below the position where the electrode plate 30 (sliding contact member) is in sliding contact with the end surface of the shaft portion 12a of the charging roller 12 (rotating member). It is formed to protrude. That is, the saucer portion 22c is formed in a dish shape so as to cover the lower space of the sliding contact position between the shaft portion 12a and the electrode plate 30, and is formed so as to collect falling objects falling at that position (upper surface). Has been.
With such a configuration, even when the charging roller 12 rotates and the electrode plate 30 is in sliding contact with the end surface of the shaft portion 12a to generate shaving powder from the electrode plate 30 or the shaft portion 12a, the shaving powder is As a fallen object, it falls on the tray 22c of the bearing 22 and is collected without falling and adhering onto the photosensitive drum 11 positioned below. Thereby, it is possible to prevent a problem that an abnormal image is generated in the toner image formed on the photosensitive drum 11 due to the metal material shavings adhering to the photosensitive drum 11.

  Note that the tray 22c of the bearing 22 is connected to the charging roller 12 in order to reliably prevent the problem that the dust generated from the sliding contact position between the electrode plate 30 and the shaft portion 12a adheres to the photosensitive drum 11 in this manner. As shown in FIG. 6, it is preferable to form at least a region below the shaft portion 12 a and a region facing the photosensitive drum 11 when viewed in a cross section orthogonal to the rotation axis direction.

  Moreover, it is preferable to form the upper surface of the saucer part 22c with a viscous material so that the shavings (falling material) deposited on the upper surface of the saucer part 22c (collecting part) do not spill and scatter from the saucer part 22c. . Specifically, a viscous material such as an adhesive can be applied to the upper surface of the saucer portion 22c, or a viscous member such as a double-sided tape can be attached to the upper surface of the saucer portion 22c. With such a configuration, the shavings dropped on the saucer part 22c adheres to the upper surface of the saucer part 22c, and it is difficult for it to spill and scatter from there.

  In the present embodiment, the shape of the tip of the shaft portion 12a and the tip of the second contact portion 30b is formed in a hemispherical shape in order to make it difficult for shaving to be generated by sliding contact between the electrode plate 30 and the shaft portion 12a. The contact area between both members 12a and 30 can be reduced. Further, conductive grease can be applied to the sliding contact position between the electrode plate 30 and the shaft portion 12a.

In addition, the shape of the saucer part 22c formed in the bearing 22 is not limited to the thing of this Embodiment, For example, as shown in FIG. 9, ranges other than the upper surface of the axial part 12a which protrudes from the bearing 22 are shown. It can also form in a bag shape so that it may cover. Even in such a case, the same effect as that of the present embodiment can be obtained.
Further, as shown in FIG. 10, even when the electrode plate 30 (second contact portion 30 b) is configured to be in sliding contact with the peripheral surface of the shaft portion 12 a instead of the end surface of the shaft portion 12 a, the sliding is also performed. By forming the tray part 22c so as to protrude toward the lower space of the contact position, the same effect as that of the present embodiment can be obtained.

  As described above, according to the present embodiment, in the bearing 22 where the shaft portion 12a of the charging roller 12 (rotating member) is rotatably held, the electrode plate 30 (sliding contact member) slides on the shaft portion 12a. A saucer portion 22c that projects toward a space below the contact position and collects falling objects falling at that position is provided. As a result, when the electrode plate 22 is slidably contacted with the shaft portion 12a of the charging roller 12, even if shaving powder or the like is generated from the electrode plate 22 or the shaft portion 12a, it adheres to the lower member such as the photosensitive drum 11. It is possible to make it difficult to cause problems.

In the present embodiment, the photosensitive drum 11, the charging roller 12, the cleaning blade 15a (cleaning unit), and the lubricant supply device 16 in the image forming unit are integrated to form the process cartridge 15, and the image forming unit It is designed to be compact and improve maintenance workability.
On the other hand, the developing device 13 can also be a constituent member of the process cartridge 15. Furthermore, each unit 11, 12, 13, 15a, 16 in the image forming unit may be configured as a detachable unit that is detachably (replaceable) installed in the apparatus main body 1 as a single unit without being a component of the process cartridge. it can. Even in such a case, the same effect as the present embodiment can be obtained.
In the present embodiment, the present invention is applied to the image forming apparatus equipped with the one-component developing type developing device 13 using the one-component developer. However, the two-component developing type using the two-component developer is used. Of course, the present invention can also be applied to an image forming apparatus in which the developing device 13 is mounted.

  In the present embodiment, the present invention is applied to a tandem type color image forming apparatus using the intermediate transfer belt 17. In contrast, a tandem color image forming apparatus using a transfer conveyance belt (a recording in which toner images on a plurality of photosensitive drums arranged in parallel so as to face the transfer conveyance belt are conveyed by the transfer conveyance belt. The present invention can also be applied to other image forming apparatuses such as a monochrome image forming apparatus. Even in such a case, the same effect as in the present embodiment can be obtained.

  In the present embodiment, in the configuration in which the electrode plate 30 as the sliding contact member is in sliding contact with the shaft portion 12a of the charging roller 12 as the rotating member, the bearing 22 that rotatably holds the shaft portion 12a of the charging roller 12 is used. The present invention was applied to this. However, the application of the present invention is not limited to this, and any sliding member (for example, a ground plate or the like) is attached to the shaft portion of another rotating member (for example, a developing roller, a transfer roller, or a fixing roller). In the configuration in which the shaft portion of the rotating member is rotatably held, the present invention can be applied to a bearing that rotatably holds the shaft portion of the rotating member. Even in such a case, the same effect as the present embodiment can be obtained by forming the tray portion on the bearing so as to protrude toward the space below the position where the sliding member slides on the rotating member. Can be obtained.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

1 image forming apparatus body (apparatus body),
11, 11Y, 11M, 11C, 11B Photosensitive drum (image carrier),
12 Charging roller (rotating member),
12a shank,
12b Hasuba gear,
15 process cartridge,
21 Cleaning roller,
22 bearings,
22a charging roller bearing, 22b cleaning roller bearing,
22c saucer part,
24 compression spring (biasing member),
25.
30 electrode plate (sliding contact member),
30a 1st contact part,
30b second contact portion,
100 body side plate,
110 Main body electrode plate.

JP-A-5-303263

Claims (6)

A bearing in which a shaft portion of a rotating member is rotatably held,
A bearing comprising: a tray portion that protrudes from an end surface of the shaft portion toward a space below a position where the sliding contact member is in sliding contact, and that collects falling objects falling at the position.   The bearing according to claim 1, wherein an upper surface of the tray portion is made of a viscous material. A process cartridge that is detachably attached to the image forming apparatus main body,
An image carrier that rotates in a predetermined direction;
A charging roller disposed at a position above the image carrier and rotating in a predetermined direction to charge the image carrier;
An electrode plate that is in sliding contact with the end surface of the shaft portion on one end side of the charging roller and that applies a predetermined voltage to the charging roller;
With
The rotating member is the charging roller,
The sliding contact member is the electrode plate,
3. A process cartridge in which the bearing according to claim 1 or 2 is installed on a shaft portion on the one end side of the charging roller.   The tray portion of the bearing is formed so as to cover at least a region below the shaft portion and a region facing the image carrier when viewed in a cross section orthogonal to the rotation axis direction of the charging roller. The process cartridge according to claim 3.   The charging roller is provided with a helical gear that meshes with a helical gear provided on the image carrier, and the direction in which the charging roller thrusts in the direction of the rotation axis is separated from the one end side by the force acting on the helical gear. 5. The process cartridge according to claim 3, wherein the process cartridge is formed in a direction.   An image forming apparatus comprising the process cartridge according to claim 3 in the image forming apparatus main body.

Images