JP6611073B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device for developing a latent image formed on the surface of an image carrier such as a photosensitive drum or a photosensitive belt, a process cartridge including the developing device, a copying machine including the same, a printer, a facsimile, In addition, the present invention relates to an image forming apparatus using an electrophotographic system such as a multi-function machine, and more particularly to a developing device, a process cartridge, and an image forming device using a two-component developer.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a developing device containing a two-component developer (including a case where an additive or the like is added) composed of a toner and a carrier is included. For the purpose of accelerating the charging of the developer carried on the developing roller while reducing the above, on the back surface of the regulating member main portion (nonmagnetic plate) made of a nonmagnetic material in the developer regulating member (doctor blade), One in which a magnetic member (magnetic plate) is installed in close contact is known (for example, see Patent Document 1).

  In a developing device using a two-component developer, toner is appropriately replenished into the developing device from a toner replenishing port provided in a part of the developing device according to toner consumption in the developing device. The replenished toner is agitated and mixed together with the developer in the developing device by a conveying member such as a conveying screw. Part of the stirred and mixed developer is supplied to a developing roller (developer carrier). The developer carried on the developing roller is regulated to an appropriate amount by a doctor blade (developer regulating member) installed so as to face the developing roller, and then the toner in the two-component developer is transferred to the photosensitive drum (image). It adheres to the latent image on the photosensitive drum at a position facing the carrier.

  On the other hand, in Patent Document 1, for the purpose of stabilizing the amount of developer carried on the developing roller toward the developing region, a regulating member main portion (non-magnetic) in a developer regulating member (regulating blade). A technique is disclosed in which the tip of a magnetic member (magnetic plate) is projected from the tip of the plate toward the developing roller (developing sleeve) in the longitudinal direction.

In a conventional developing device, during operation, a large pressure is applied by the developer G staying at the position of the doctor gap where the developing roller and the developer regulating member face each other or in the vicinity thereof, or by the developer carried on the developing roller. In some cases, the developing roller may be bent in a substantially arcuate shape due to acting on the developing roller or the weight of the developing roller itself acting on the developing roller.
When the developing roller is bent in such a manner, the doctor gap with the developer regulating member is not uniform in the longitudinal direction, and the developer amount (pumping amount) on the developing roller regulated by the developer regulating member. However, it is not uniform over the longitudinal direction, and an image density deviation occurs in the toner image formed on the image carrier (photosensitive drum).

  The present invention has been made to solve the above-described problems. Even when the developing roller is bent, the amount of developer on the developing roller regulated by the developer regulating member is made uniform in the longitudinal direction. The present invention provides a developing device, a process cartridge, and an image forming apparatus.

A developing device according to the present invention is a developing device for developing a latent image formed on the surface of an image carrier while containing a developer having a carrier and a toner, and developing the latent image on the surface of the image carrier. agent and a developing roller that rotates in a predetermined direction while carrying, is disposed so as to face the predetermined face direction against the developing roller, the developer regulating the amount of developer carried on the developing roller A regulating member, and the developer regulating member is formed of a non-magnetic material and is opposed to the developing roller, and is fixedly installed so as to contact the regulating member main part. A magnetic member facing the developing roller closer to the developing roller than the main part of the regulating member, and at least both longitudinal end portions and a central portion corresponding to the rotation axis direction of the developing roller with respect to the developing device. Is fixed Is, the developing roller, comprising a sleeve, and a magnet disposed in the non-rotating inside the sleeve, the magnetic member of said developer regulating member is in a state where the deflection of the facing direction does not occur The length protruding in the opposite direction from the virtual line parallel to the developing roller toward the developing roller is formed so that the central portion in the longitudinal direction is longer than both end portions in the longitudinal direction. It is a thing.

  According to the present invention, a developing device, a process cartridge, and an image forming apparatus in which the amount of developer on the developing roller regulated by the developer regulating member is made uniform in the longitudinal direction even when the developing roller is bent. 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. (A) The schematic sectional view which looked at the upper part of the developing device in the longitudinal direction, (B) The schematic sectional view which looked at the lower part of the developing device in the longitudinal direction. FIG. 2A is a schematic cross-sectional view showing a central portion in the longitudinal direction and (B) a schematic cross-sectional view showing an end portion in the longitudinal direction in the main part of the developing device in a state where operation is stopped. (A) The schematic which shows the positional relationship of the longitudinal direction of a developing roller and a doctor blade, (B) The graph which shows the longitudinal distribution of the magnitude | size of the magnetic force of a doctor opposing pole in the magnet of a developing roller. It is a schematic perspective view which shows the state in which a doctor blade is installed in a developing case. It is a figure which shows a doctor blade as a modification in a longitudinal direction.

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 overall configuration and operation of the image forming apparatus will be described with reference to FIG.
In FIG. 1, 1 is a tandem color copier as an image forming apparatus, 2 is a writing unit that emits laser light based on input image information, 3 is a document conveying unit that conveys a document D to a document reading unit 4, and 4 is An original reading unit that reads image information of the original 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, 10Y, 10M, Reference numerals 10C and 10BK denote process cartridges (image forming units) on which toner images of respective colors (yellow, magenta, cyan, and black) are formed.

  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 20 for cleaning the belt 17 is a primary transfer bias for transferring the toner images formed on the photosensitive drums 12 of the process cartridges 10Y, 10M, 10C, and 10BK on the intermediate transfer belt 17 in an overlapping manner. A roller, 30 is a fixing device that fixes an unfixed image on the recording medium P, and 50Y, 50M, 50C, and 50BK are toner cartridges (toner containers) that contain toner of each color (yellow, magenta, cyan, black). Show.

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 12 of the process cartridges 10Y, 10M, 10C, and 10BK.

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 drum 12.

On the other hand, the photosensitive drums 12 of the four process cartridges 10Y, 10M, 10C, and 10BK are rotated counterclockwise in FIG. First, the surface of the photoconductive drum 12 is uniformly charged at a portion facing the charging roller 14 (charging portion) (this is a charging step). Thus, a charged potential is formed on the photosensitive drum 12K. Thereafter, the surface of the charged photosensitive drum 12 reaches the irradiation position of each laser beam.
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).

  The laser beam corresponding to the yellow component is applied to the surface of the photosensitive drum 12 of the first process cartridge 10Y 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 12 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 12 after being charged by the charging roller 14.

  Similarly, the laser beam corresponding to the magenta component is irradiated on the surface of the photosensitive drum 12 of the second process cartridge 10M 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 photosensitive drum 12 of the third process cartridge 10C from the left side of the drawing, thereby forming an electrostatic latent image of the cyan component. The black component laser light is applied to the surface of the photoconductive drum 12K of the fourth process cartridge 10BK from the left side of the drawing to form an electrostatic latent image of the black component.

Thereafter, the surface of the photosensitive drum 12 on which the electrostatic latent images of the respective colors are formed reaches a position facing the developing device 13 (developing unit). Then, each color toner is supplied from each developing device 13 onto the photosensitive drum 12, and the latent image on the photosensitive drum 12 is developed (this is a developing step).
Thereafter, the surface of the photoconductor drum 12 after the development process reaches a portion facing the intermediate transfer belt 17. Here, a primary transfer bias roller 20 is installed at each facing portion so as to abut on the inner peripheral surface of the intermediate transfer belt 17. Then, the toner images of the respective colors formed on the photosensitive drums 12 of the process cartridges 10Y, 10M, 10C, and 10BK are sequentially superimposed and transferred onto the intermediate transfer belt 17 at the position of the primary transfer bias roller 20. (This is a primary transfer process.)

Then, the surface of the photosensitive drum 12 after the transfer process reaches a position facing the cleaning blade 15 (cleaning unit). Then, the untransferred toner remaining on the photosensitive drum 12 is collected by the cleaning blade 15 (cleaning process).
Thereafter, the surface of the photoconductive drum 12 passes through a static elimination unit (not shown), and a series of image forming processes on the photoconductive drum 12 is completed.

On the other hand, the intermediate transfer belt 17 on which the toner images of the respective colors on the photosensitive drums 12 of the process cartridges 10Y, 10M, 10C, and 10BK are transferred (carrying) is run in the clockwise direction in the drawing and is secondary. It reaches a position facing the transfer bias roller 18. 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 30 by the conveyance belt. In the fixing device 30, 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 a paper discharge roller, and a series of image forming processes is completed.

Next, the process cartridge 10 (image forming unit) will be described in detail with reference to FIGS.
As illustrated in FIG. 2, the process cartridge 10 includes a photosensitive drum 12 as an image carrier, a charging roller 14 as a charging unit that charges the photosensitive drum 12, and a latent image formed on the surface of the photosensitive drum 12. A developing device 13 (developing unit) for developing, a cleaning blade 15 (cleaning unit) for removing untransferred toner on the photosensitive drum 12, and a lubricant supplying device 16 (lubricant supplying) for supplying a lubricant onto the photosensitive drum 12 Part), etc. The process cartridge 10 is configured to be detachable (replaceable) from the apparatus main body 1.
Since the process cartridges of the respective colors have almost the same structure, the process cartridges, the photosensitive drums, and the developing devices are excluded from the alphabets (Y, C, M, BK) in FIGS. Illustrated.

Here, the photosensitive drum 12 as an image bearing member is a negatively charged organic photosensitive member, and a photosensitive layer or the like is provided on a drum-shaped conductive support.
Although not shown, the photosensitive drum 12 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 12, a conductive material having a volume resistance of 10 ¹⁰ Ωcm or less can be used.

The charging roller 14 serving as a charging unit is a roller member formed by coating an outer periphery of a conductive metal core (shaft) with an intermediate resistance elastic layer, and the rotation of the photosensitive drum 12 with respect to the lubricant supply device 16. It is disposed so as to contact the photosensitive drum 12 on the downstream side in the direction.
A predetermined voltage (charging bias) is applied to the charging roller 14 from a power supply unit (not shown) installed in the apparatus main body 1, thereby uniformly charging the surface of the opposing photosensitive drum 12.
In the present embodiment, the charging roller 14 is in contact with the photosensitive drum 12, but the charging roller 14 may be opposed to the photosensitive drum 12 with a small gap therebetween.

The cleaning blade 15 (cleaning unit) is disposed on the downstream side in the rotation direction of the photosensitive drum 12 with respect to the lubricant supply device 16. The cleaning blade 15 is made of a rubber material such as urethane rubber, and is in contact with the surface of the photosensitive drum 12 at a predetermined angle and a predetermined pressure. As a result, deposits such as untransferred toner adhering to the photosensitive drum 12 are mechanically scraped and collected in the process cartridge 10. The toner collected in the process cartridge 10 is disposed as a waste toner in a waste toner collection container (not shown, and is detachably installed on the back side of the apparatus main body 1 in FIG. 1 in the direction perpendicular to the paper surface). It is conveyed toward the conveying screw 15b. Here, examples of the adhering matter adhering to the photosensitive drum 12 include paper powder generated from the recording medium P (paper) in addition to the untransferred toner, and a discharge product generated on the photosensitive drum 12 when discharged by the charging roller 14. And additives added to the toner.
The cleaning blade 15 in the present embodiment also functions as a thinning blade that thins the lubricant supplied onto the photosensitive drum 12 by the lubricant supply roller 16a.

The lubricant supply device 16 (lubricant supply unit) holds the solid lubricant 16b, the lubricant supply roller 16a (brush-shaped roller) that is in sliding contact with the photosensitive drum 12 and the solid lubricant 16b, and the solid lubricant 16b. A compression spring 16c that urges the holding member 16e toward the lubricant supply roller 16a together with the member 16e and the solid lubricant 16b is formed.
The lubricant is supplied onto the photosensitive drum 12 by the lubricant supply device 16 configured as described above. Then, the lubricant supplied onto the photosensitive drum 12 is thinned by the cleaning blade 15 disposed on the downstream side of the lubricant supply device 16.

  2 and 3, the developing device 13 has a developing roller 13a as a developer carrying member disposed so as to face the photosensitive drum 12 with a minute gap between them. A developing area (developing nip portion) where the photosensitive drum 12 and the magnetic brush come into contact is formed. A developer G (two-component developer) composed of toner T and carrier C is accommodated in the developing device 13. The developing device 13 develops the electrostatic latent image formed on the photosensitive drum 12 (forms a toner image). The configuration and operation of the developing device 13 will be described in detail later.

Referring to FIG. 1, toner cartridges 50Y, 50M, 50C, and 50BK (toner containers) contain toner T to be supplied into developing device 13 therein. Specifically, based on the information of the toner concentration (the ratio of the toner T in the developer G) detected by the magnetic sensor 13h (see FIG. 3) installed in the developing device 13, it is not shown. The toner T is appropriately replenished from the toner replenishing port 13e from the corresponding toner cartridge of the four toner cartridges 50Y, 50M, 50C, and 50BK into the developing device 13 through the toner replenishing device.
The replenishment of the toner T is not limited to the toner density information, but is performed based on the image density information detected from the reflectance of the toner image formed on the photosensitive drum 12, the intermediate transfer belt 17, or the like. May be. Further, it may be determined that toner T is replenished by combining these different pieces of information.
Further, as a toner replenishing device for replenishing toner to the developing device 13, a toner replenishing device that transports toner using a transport auger, a device that transports toner with air using a screw pump, and the like are known. Things can be used.
Further, the four toner cartridges 50Y, 50M, 50C, and 50BK are configured to be detachable from the apparatus main body from the back side in the vertical direction (the front side in the operation direction) of the apparatus main body 1 in FIG. When the toner in the cartridge runs out, it is replaced with a new one.

Hereinafter, the developing device 13 in the image forming apparatus will be described in detail.
2 and 3, the developing device 13 includes a developing roller 13a as a developer carrier, conveying screws 13b1 and 13b2 (auger screws) as conveying members, a doctor blade 13c as a developer regulating member, and the like. It consists of
An opening is formed in the developing case 13k of the developing device 13 in order to expose a part of the developing roller 13a to the photosensitive drum 12 side. In the developing roller 13a, a sleeve 13a2 formed of a non-magnetic material in a cylindrical shape is rotated by a rotation driving mechanism (not shown) (a driving gear meshing with a gear installed on the sleeve shaft is installed). It is configured as follows.
The sleeve 13a2 can be formed of a nonmagnetic material such as aluminum, stainless steel, brass, or conductive resin. However, in this embodiment, emphasis is placed on ease of processing, low cost, and light weight. The sleeve 13a2 is made of aluminum.

  In the sleeve 13a2 of the developing roller 13a, a magnet 13a1 that forms a plurality of magnetic poles (refer to the S1 to S3 poles and the N1 to N2 poles described in FIG. 4) on the peripheral surface of the sleeve 13a2 is fixed in a non-rotating manner. (The magnet shaft is lightly press-fitted into the side plate.) The developer G carried on the developing roller 13a is conveyed as the developing roller 13a (sleeve 13a2) rotates in the direction of the arrow, and reaches the position of the doctor blade 13c (developer regulating member). The developer G on the developing roller 13a is regulated to an appropriate amount at this position, and then conveyed to a position facing the photosensitive drum 12 (developing area). The toner is attracted to the latent image formed on the photosensitive drum 12 by the electric field (developing electric field) formed in the developing area.

The doctor blade 13c as a developer restricting member includes a substantially plate-like magnetic member 13c2 (magnetic plate) made of a magnetic material on a substantially plate-like blade main portion 13c1 (regulating member main portion) made of a nonmagnetic material. ) Are in close contact with each other and are disposed so as to face the upper side of the developing roller 13a. The developing roller 13a rotates in the clockwise direction in FIG. 2, and the photosensitive drum 12 rotates in the counterclockwise direction in FIG.
The doctor blade 13c will be described in more detail later.

The two conveying screws 13b1 and 13b2 (conveying members) allow the developer G accommodated in the developing device 13 to move in the longitudinal direction (the vertical direction in FIG. 2 and the left and right direction in FIG. 3), and the developing roller 13a. In the same direction as the rotation axis direction).
The first transport screw 13b1 as the first transport member is disposed at a position facing the developing roller 13a, and transports the developer G horizontally in the longitudinal direction (rotation axis direction) (see FIG. 3A). At the same time, the developer G is supplied onto the developing roller 13a at the position of the pumping magnetic pole (supply in the direction of the white arrow in FIG. 3A).

The second conveying screw 13b2 as the second conveying member is disposed at a position facing the developing roller 13a at a position below the first conveying screw 13b1. The developer G released from the developing roller 13a (the developer G released from the developing roller 13a by the agent separating magnetic pole after the developing process, which is released in the direction of the white arrow in FIG. 3B). Are transported horizontally in the longitudinal direction (the transport in the right direction indicated by the broken line arrow in FIG. 3B).
Then, the second transport screw 13b2 secondly supplies the developer G circulated from the downstream side of the transport path by the first transport screw 13b1 via the first relay portion 13g to the upstream side of the transport path by the first transport screw 13b1. It conveys via the relay part 13f (it is the conveyance shown by the dashed-dotted arrow of FIG. 3).
The two conveying screws 13b1 and 13b2 are arranged so that the rotation axis is substantially horizontal, like the developing roller 13a and the photosensitive drum 12. Moreover, as for the two conveyance screws 13b1 and 13b2, both have a screw part helically wound around the rotating shaft part.

The conveyance path (first conveyance path) by the first conveyance screw 13b1 and the conveyance path (second conveyance path) by the second conveyance screw 13b2 are isolated from each other by a wall portion.
Referring to FIG. 3, the downstream side of the transport path (second transport path) by the second transport screw 13b2 and the upstream side of the transport path (first transport path) by the first transport screw 13b1 are the second relay unit. It communicates via 13f. The developer G that has reached the downstream side of the second conveyance path by the second conveyance screw 13b2 stays in the vicinity of the second relay portion 13f and rises up, and the first conveyance screw 13b1 makes the first through the second relay portion 13f. It is transported (supplied) to the upstream side of the transport path.
In addition, the downstream side of the conveyance path by the first conveyance screw 13b1 and the upstream side of the conveyance path by the second conveyance screw 13b2 communicate with each other via the first relay portion 13g. Then, the developer G that has not been supplied onto the developing roller 13a in the first conveyance path by the first conveyance screw 13b1 falls by its own weight at the first relay portion 13g and reaches the upstream side of the second conveyance path. become.
In addition, in order to improve the transportability of the developer in the second relay portion 13f (delivery of the developer against the direction of gravity from the second transport path to the first transport path), the second transport screw 13b2 A paddle-shaped portion or a screw portion in which the screw winding direction is formed in the reverse direction can also be provided at a downstream position (a position corresponding to the second relay portion 13f).

  With such a configuration, a circulation path for circulating the developer G in the longitudinal direction in the developing device 13 is formed by the two conveying screws 13b1 and 13b2. That is, when the developing device 13 is operated, the developer G accommodated in the device flows in the direction of the broken arrow in FIG. Thus, the developer G supply path to the developing roller 13a (the first transport path by the first transport screw 13b1) and the developer G recovery path (second transport screw) separated from the developing roller 13a. 13b2), the density deviation of the toner image formed on the photosensitive drum 12 can be reduced.

  2 and 3A, in the conveyance path by the first conveyance screw 13b1 (below the first conveyance screw 13b1 and at the upstream side of the first conveyance path). A magnetic sensor 13h (toner concentration detecting means) for detecting the toner concentration of the developer circulating in the apparatus is installed. Based on the toner density information detected by the magnetic sensor 13h, the toner cartridge 50 is directed into the developing device 13 through the toner supply port 13e (located in the vicinity of the second relay portion 13f). Then, new toner T is supplied.

Referring to FIG. 3, the toner replenishing port 13e is located above the upstream side of the conveyance path by the first conveyance screw 13b1 and away from the development area (outside the longitudinal range of the development roller 13a). Is).
In the present embodiment, the toner replenishing port 13e is disposed in the conveying path by the first conveying screw 13b1, but the position of the toner replenishing port 13e is not limited to this, and for example, in the second conveying path. It can also be arranged above the upstream side.

Hereinafter, the characteristic configuration and operation of the developing device 13 (process cartridge 10) according to the present embodiment will be described in detail with reference to FIGS.
The developing device 13 according to the present embodiment includes a doctor blade as a developer regulating member that regulates the amount of the developer G carried on the developing roller 13a as described above with reference to FIGS. 13c is arranged to face the developing roller 13a.
4 to 6, the doctor blade 13c (developer regulating member) mainly includes a blade main portion 13c1 (nonmagnetic plate) as a regulating member main portion, and a magnetic member 13c2 (magnetic plate). , Is composed of.

The blade main portion 13c1 (regulating member main portion) is a substantially rectangular plate-like member that is made of a nonmagnetic material such as aluminum and is disposed so as to face the developing roller 13a. In the present embodiment, the tip of the blade main portion 13c1 (the portion that forms a doctor gap facing the developing roller 13a) is formed in a substantially horizontal plane.
The magnetic member 13c2 is fixed and installed so as to contact the blade main portion 13c1 (regulating member main portion), and is a plate disposed so as to face the developing roller 13a closer to the blade main portion 13c1. It is a shaped member. The magnetic member 13c2 is formed of a magnetic metal material such as magnetic stainless steel having a plate thickness (for example, about 0.1 to 1.0 mm) thinner than the plate thickness of the blade main portion 13c1.

In this way, the magnetic member 13c2 is installed on the nonmagnetic blade main portion 13c1, and the doctor blade 13c is configured so that the tip end of the magnetic member 13c2 protrudes from the tip end of the blade main portion 13c1, thereby developing the developer G. The amount of the developer G carried on the developing roller 13a toward the developing region through the position of the doctor gap while accelerating the charging of the developer G carried on the developing roller 13a while reducing the deterioration of the toner. Can be stabilized.
In the present embodiment, the tip portion of the magnetic member 13c2 (the portion that forms the doctor gap facing the developing roller 13a) is formed in a curved shape (convex shape downward). This will be described in detail later.

Further, in the present embodiment, the doctor blade 13c (developer regulating member) is a developing device so as not to bend in the facing direction (the vertical direction in FIGS. 4 and 5) facing the developing roller 13a. 13, at least both ends and the center of the longitudinal direction (the direction corresponding to the rotation axis direction of the developing roller 13a) are fixedly installed. That is, the doctor blade 13c is bent in a substantially arcuate shape with the rotation axis of the developing roller 13a as a reference, and the gap (doctor gap) with the developing roller 13a (the developing roller 13a in a state where no bending occurs) changes. It is fixed and installed in the developing device 13 so that it does not occur.
Specifically, in the present embodiment, the doctor blade 13c is in the longitudinal direction (the direction corresponding to the rotation axis direction of the developing roller 13a, which is the vertical direction in FIG. 4 and the left-right direction in FIG. 5). Both end portions and the central portion are fixed to attachment portions of the developing device 13 (developing case 13k) by fastening screws 13n.

More specifically, with reference to FIGS. 4 to 6, a planar attachment portion for attaching the doctor blade 13 c in surface contact is formed in the developing case 13 k. In addition, female screw portions 13k1 are formed at three portions of the attaching portion of the developing case 13k, that is, both ends in the longitudinal direction and the central portion in the longitudinal direction.
Also, the blade main portion 13c1 of the doctor blade 13c is also provided with three screw fastening holes at positions corresponding to the female screw portion 13k1 of the developing case 13k, at three positions of the longitudinal end portions and the longitudinal center portion. A portion 13c10 is formed.
In the present embodiment, the back surface of the blade main portion 13c1 (the surface on the side facing the mounting portion of the developing case 13k) is not disturbed by the contact between the hole 13c10 and the female screw portion 13k1. The magnetic member 13c2 (magnetic plate) is joined by an adhesive or welding in a state of surface contact. Further, the attachment portion of the developing case 13k has a thickness (or slightly larger than the plate thickness) of the magnetic member 13c2 so that the magnetic member 13c2 does not hinder the surface contact between the blade main portion 13c1 and the attachment portion. Step) is provided. Further, in the present embodiment, in order to appropriately adjust the size of the doctor gap, the hole 13c10 of the blade main portion 13c1 is a long hole (a long hole whose longitudinal direction is the direction facing the developing roller 13a). Can also be).
Then, the screws 13n are screwed into the three female screw portions 13k1 of the developing case 13k through the three hole portions 13c10 of the blade main portion 13c1, so that the doctor blade 13c becomes the developing case 13k (the developing device 13). ) Will be fixed and installed.

  As described above, the doctor blade 13c is provided at three positions, both in the longitudinal direction at both ends and in the longitudinal direction, with respect to the attachment portion of the developing case 13k, and fixed portions are provided at approximately a plurality of positions in the longitudinal direction. Since the doctor blade 13c is fixed / installed, the doctor blade 13c is more reliably bent (deformed) than the case where the doctor blade 13c is fixed / installed at two positions on both ends in the longitudinal direction with respect to the mounting portion of the developing case 13k. Can be reduced. That is, with the above-described configuration, the doctor blade 13c (the blade main portion 13c1 and the magnetic member 13c2) has a pressure (agent pressure) by the developer G carried on the developing roller 13a at the position of the doctor gap facing the developing roller 13a. Even if it receives, it becomes easy to maintain a desired doctor gap over a longitudinal direction, without producing the bending which a doctor gap spreads in a longitudinal direction center part.

In this embodiment, the doctor blade 13c is screwed to the attachment portion of the developing case 13k at three positions in the longitudinal direction. However, the doctor blade 13c is attached to the attachment portion of the developing case 13k at four positions in the longitudinal direction. The screw can be fastened as described above. However, in this case, the screw positions are arranged so as to include at least both ends in the longitudinal direction and the central portion in the longitudinal direction so as to prevent the doctor blade 13c from being bent (deformed).
In the present embodiment, the doctor blade 13c may be fixed to the attachment portion of the developing case 13k using an adhesive or the like instead of using the screw 13n.

Here, as described above with reference to FIG. 3 and the like, in the present embodiment, the developing roller 13a has the magnet 13a1 installed non-rotatingly inside the sleeve 13a2.
Then, referring to FIG. 5, in the present embodiment, magnet 13a1 is a magnetic pole formed at a position facing doctor blade 13c or in the vicinity thereof (the doctor facing pole N1 shown in FIG. 4). The range M in the longitudinal direction (the direction corresponding to the rotation axis direction of the developing roller 13a) includes the range W in the longitudinal direction of the magnetic member 13c2 of the doctor blade 13c.

Specifically, the doctor facing pole N1 formed by the magnet 13a1 has a longitudinal range M in which the magnetic force is generated, like the other magnetic poles (the S1 to S3 poles and the N2 poles in FIG. 4). It almost coincides with the longitudinal range M of 13a1. However, the magnitude of the magnetic force is not uniform in the longitudinal direction, and for manufacturing reasons, as shown in FIG. 5B, both ends in the longitudinal direction (in the range of several mm) are local. The other range N becomes the magnetic force stable range, and the magnitude of the magnetic force becomes uniform.
In the present embodiment, since the magnetic member 13c2 is provided in the magnetic force stability range N inside the longitudinal range M of the doctor counter pole N1, the developing roller is stabilized by the magnetic force stable in the magnetic force stability range N. Since the developer G carried in a uniform amount in the longitudinal direction on 13a is further optimized by the magnetic member 13c2, the pumping amount of the developer on the developing roller 13a is made uniform in the longitudinal direction ( The pumping deviation will be stable).
In the present embodiment, both ends in the longitudinal direction of the magnet 13a1 (the portions where the magnetic force increases) are areas covered by side seals provided at both ends in the longitudinal direction of the opening of the developing case 13k. Thus, the non-development area does not contribute to the development process.

Here, referring to FIGS. 4 to 6, in the present embodiment, the magnetic member 13c2 of the doctor blade 13c (developer regulating member) has a length protruding in the facing direction toward the developing roller 13a. The central part in the longitudinal direction is formed to be longer than both ends in the longitudinal direction. Specifically, the magnetic member 13c2 is formed such that the length protruding in the facing direction toward the developing roller 13a is longer by 20 to 100 μm in the central portion in the longitudinal direction than both ends in the longitudinal direction.
That is, the magnetic member 13c2 is formed such that a gap (doctor gap) with respect to the developing roller 13a in a state where no bending in the opposing direction occurs is smaller in the center portion in the longitudinal direction than in both end portions in the longitudinal direction. Specifically, as shown in FIG. 5A, in the present embodiment, both ends in the longitudinal direction of the developing roller 13a in an unused state (or operation stopped state) in which no bending occurs and the magnetic member 13c2 are used. The gap H1 in the central portion in the longitudinal direction is formed to be smaller by 20 to 100 μm than the gap H2 in the portion.

  In this configuration, the developing roller 13a has shafts at both ends in the longitudinal direction supported by the developing case 13k. When the developing device 13 is in operation (in use), the developing roller 13a, the doctor blade 13c, In the vicinity of the doctor gap facing or near the developer gap, a large pressure acts on the developing roller 13a due to the developer G staying at the position or the developer G carried on the developing roller 13a, or the developing roller 13a itself. This is because the weight acts on the developing roller 13a and the developing roller 13a bends in a substantially arcuate shape as indicated by the one-dot chain line in FIG. That is, unlike the present embodiment, when the tip of the magnetic member 13c2 is a horizontal plane, the magnetic member 13c2 (doctor blade 13c) may be deformed if the developing roller 13a bends during the operation. The developer gap on the developing roller 13a regulated by the doctor blade 13c (magnetic member 13c2) is not uniform in the longitudinal direction, and the photosensitive drum is not uniform in the longitudinal direction. Therefore, an image density deviation occurs in the toner image formed on the toner image 12.

On the other hand, in the present embodiment, the shape of the tip of the original magnetic member 13c2 is matched to the bending of the developing roller 13a so as to cancel the change in the doctor gap due to the bending of the developing roller 13a during operation. Is formed in a convex shape downward. As a result, even if the developing roller 13a bends during operation, the gap between the developing roller 13a and the magnetic member 13c2 is substantially uniform in the longitudinal direction, and therefore the developer on the developing roller 13a regulated by the doctor blade 13c. The amount (pumping amount) is also made uniform over the longitudinal direction. Therefore, a problem that an image density deviation is generated in the toner image formed on the photosensitive drum 12 is surely reduced.
In particular, in the present embodiment, as described above, the doctor blade 13c (the blade main portion 13c1 and the magnetic member 13c2) is configured not to bend, and furthermore, the magnetic field stability range of the doctor counter pole N1. Since the doctor gap is formed of N, the above-described effects are surely exhibited.

Further, in the present embodiment, as described above, the doctor blade 13c (developer regulating member) is disposed so as to face the developing roller 13a at an upper position. Therefore, a large pressure is applied to the developing roller 13a due to the developer G staying at or near the doctor gap and the developer G carried on the developing roller 13a, or the weight of the developing roller 13a itself is the developing roller. The developing roller 13a is likely to be bent.
Furthermore, since the sleeve 13a2 of the developing roller 13a is formed of aluminum having a relatively low mechanical strength, the developing roller 13a is likely to be bent.
Also from these things, it becomes useful to form the magnetic member 13c2 in a substantially convex shape as described above.

In the present embodiment, the shape of the tip of the magnetic member 13c2 is formed in a substantially convex shape according to the degree of bending of the developing roller 13a during operation, but the shape of the tip of the blade main portion 13c1 is Since the developing roller 13a bends during operation because of the horizontal planar shape, the gap between the developing roller 13a and the blade main portion 13c1 is narrow at both ends in the longitudinal direction and widened at the center in the longitudinal direction. However, the important characteristics regarding the developing ability such as the amount of pumping of the developing roller 13a and the charging quality of the developer G passing through the position of the doctor gap are different from the developing roller 13a and the blade main portion 13c1 in comparison with the gap between the developing roller 13a and the blade main portion 13c1. Since the gap between 13a and the magnetic member 13c2 is dominant, the above-described effects of the present invention are not affected. That is, the gap between the developing roller 13a and the magnetic member 13c2 functions as a main doctor gap.
In the present embodiment, the tip of the magnetic member 13c2 is formed in a substantially convex shape in accordance with the degree of bending of the developing roller 13a during operation. When the developing roller 13a is not bent, the gap between the developing roller 13a and the magnetic member 13c2 is wide at both ends in the longitudinal direction and narrows at the center in the longitudinal direction (H1 <H2 .) For this reason, when the developing roller 13a is not bent, the above-described gap H1 is less than 0 so that the magnetic member 13c2 does not come into contact with the surface of the developing roller 13a and damage the surface of the developing roller 13a. It is preferable to set so that it may become large.

Further, in the present embodiment, the magnetic member 13c2 has a curved tip at the front end facing the developing roller 13a. That is, the tip of the magnetic member 13c2 is formed in a substantially convex shape toward the developing roller 13a so as to draw a gentle curve locus from both ends in the longitudinal direction to the center in the longitudinal direction.
The bending of the developing roller 13a has a curved shape as indicated by the one-dot broken line in FIG. 5A, and therefore the tip of the magnetic member 13c2 is formed so as to match the shape. The effect of is surely demonstrated.

In the present embodiment, the tip of the magnetic member 13c2 in the doctor blade 13c is formed in a curved shape. However, the shape of the tip of the magnetic member 13c2 is not limited to this, and it is sufficient that the doctor gap of the magnetic member 13c2 is substantially uniform in the longitudinal direction in accordance with the bending shape of the developing roller 13a during operation. .
For example, as shown in FIG. 7A, the tip of the magnetic member 13c2 is linearly inclined from both ends in the width direction toward the center in the width direction and is substantially convex toward the developing roller 13a. It can also be formed.
Further, as shown in FIG. 7B, the tip of the magnetic member 13c2 is linearly inclined from the both ends in the width direction toward the flat range from the center in the width direction toward the developing roller 13a. It can also be formed in a substantially convex shape.
However, as shown in FIG. 5, if the tip of the magnetic member 13c2 is formed in a curved shape in accordance with the bending of the developing roller 13a, the accuracy with which the doctor gap is made uniform in the longitudinal direction is improved. Compared with the example of the example, the effect of the present invention is greatly exhibited.

Further, in the present embodiment, three screw fastening holes 13c10 are formed only in the blade main part 13c1 of the doctor blade 13c, and these holes 13c10 are positioned at the positions of the female screw parts 13k1 of the developing case 13k. Screwed together.
On the other hand, as shown in FIG. 7, in addition to the three holes 13c10 formed in the blade main part 13c1 of the doctor blade 13c, the magnetic member 13c2 also has a screw fastening hole 13c20 at a position corresponding to them. Can be formed in three places, and the holes 13c10 and 13c20 can be screwed in accordance with the position of the female screw portion 13k1 of the developing case 13k. In this case, the magnetic member 13c2 directly comes into surface contact with the attachment portion of the developing case 13k, and the blade main portion 13c1 faces the attachment portion via the magnetic member 13c2.
Even in such a case, the bending of the doctor blade 13c (the blade main portion 13c1 and the magnetic member 13c2) can be reduced. Even when such a doctor blade 13c is used, the gap between the developing roller 13a and the magnetic member 13c2 that bends during operation can be made substantially uniform over the longitudinal direction.

As described above, the developing device 13 according to the present embodiment has the doctor blade 13c (developer) provided with the magnetic member 13c2 opposed to the developing roller 13a closer to the developing roller 13a than the blade main portion 13c1 (regulating member main portion). The regulating member is fixed to the developing device 13 at least at both ends in the longitudinal direction and at the center in the longitudinal direction. The magnet 13a1 provided in the developing roller 13a is configured such that the longitudinal range M of the doctor facing pole N1 includes the longitudinal range W of the magnetic member 13c2 of the doctor blade 13c. The magnetic member 13c2 of the doctor blade 13c is formed such that the length protruding toward the developing roller 13a is longer at the center in the longitudinal direction than at both ends in the longitudinal direction.
Thereby, even if the developing roller 13a is bent, the amount of developer on the developing roller 13a regulated by the doctor blade 13c can be made uniform over the longitudinal direction.

In the present embodiment, the present invention is applied to the image forming apparatus 1 in which the developing device 13 is unitized as a constituent member of the process cartridge 10 together with other image forming members. However, the application of the present invention is not limited to this, and the developing device 13 is not formed as a process cartridge but is configured to be detachably installed as a single unit with respect to the image forming apparatus. Of course, the present invention can be applied.
In the present application, the “process cartridge” refers to a charging unit that charges the image carrier, a developing device (developing unit) that develops a latent image formed on the image carrier, and a cleaning on the image carrier. It is defined as a unit in which at least one of the cleaning units and the image carrier are integrated and installed detachably with respect to the image forming apparatus main body.

Further, in the present embodiment, the present invention is applied to the developing device 13 in which one developing roller 13a is installed and two conveying screws as conveying members are installed in the vertical direction. However, the application of the present invention is not limited to this, and the present invention can be applied to various types of developing devices. For example, a developing device in which two or more developing rollers are arranged in parallel in the vertical direction so that the developing roller faces the image carrier, a developing device in which two conveying screws are arranged in parallel in the horizontal direction, or three or more conveying devices Naturally, the present invention can also be applied to a developing device in which a screw is installed, a developing device in which a paddle-like roller is used as a conveying member, and the like.
Even in such a case, the same effect as this embodiment can be obtained.

  In this embodiment, the toner T is supplied from the toner container 28 toward the developing device 13, but the developer G (toner T and carrier C) is directed toward the developing device 13 from the toner container (developer container). It can also be supplied. In that case, a means for appropriately discharging excess developer from the developing device 13 is provided. Even in such a case, the same effect as in the present embodiment 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 (image forming apparatus main body),
10, 10Y, 10M, 10C, 10BK process cartridge,
12 Photosensitive drum (image carrier),
13 Development device,
13a Development roller (developer carrier),
13a1 magnet,
13a2 sleeve,
13c Doctor blade (developer regulating member),
13c1 blade main part (regulator member main part),
13c2 magnetic member (magnetic plate),
13c10, 13c20 hole (fixed part),
13k development case (mounting part),
13k1 female thread,
G Developer.

JP 2014-89386 A

Claims (11)

A developing device for containing a developer having a carrier and a toner and developing a latent image formed on the surface of the image carrier,
A developing roller that faces the image carrier and rotates in a predetermined direction while carrying a developer;
Is disposed so as to face the predetermined face direction against the developing roller, and a developer regulating member for regulating the amount of developer carried on the developing roller,
With
The developer regulating member is made of a non-magnetic material and is disposed so as to be in contact with the regulating member main part facing the developing roller. A magnetic member facing and adjacent to the developing roller, and at least a longitudinal end portion and a central portion corresponding to the rotational axis direction of the developing roller are fixedly installed with respect to the developing device,
The developing roller includes a sleeve and a magnet that is non-rotatably installed inside the sleeve ,
The magnetic member of the developer regulating member has a length protruding in the facing direction from a virtual line parallel to the developing roller in a state in which no bending in the facing direction occurs to the developing roller side. 2. A developing device according to claim 1, wherein a central portion in the longitudinal direction is longer than both ends in the longitudinal direction. A developing device for containing a developer having a carrier and a toner and developing a latent image formed on the surface of the image carrier,
A developing roller that faces the image carrier and rotates in a predetermined direction while carrying a developer;
A developer regulating member that is disposed to face the developing roller in a predetermined facing direction and regulates the amount of developer carried on the developing roller;
With
The developer regulating member is made of a non-magnetic material and is disposed so as to be in contact with the regulating member main part facing the developing roller. A magnetic member facing and adjacent to the developing roller, and at least a longitudinal end portion and a central portion corresponding to the rotational axis direction of the developing roller are fixedly installed with respect to the developing device,
The developing roller includes a sleeve and a magnet that is non-rotatably installed inside the sleeve,
The developing device according to claim 1, wherein the magnetic member of the developer regulating member is formed such that a tip end portion is substantially convex toward the developing roller. The magnetic member is formed such that a gap with respect to the developing roller in a state where the bending in the facing direction is not generated is smaller in a central portion in the longitudinal direction than in both end portions in the longitudinal direction. The developing device according to claim 1 or 2. 4. The developing device according to claim 1, wherein a tip portion of the magnetic member facing the developing roller is formed in a curved shape along the longitudinal direction. 5. The length of the magnetic member protruding in the facing direction toward the developing roller from a virtual line parallel to the developing roller in a state where the bending in the facing direction is not generated has both end portions in the longitudinal direction. 5. The developing device according to claim 1, wherein the central portion in the longitudinal direction is longer by 20 to 100 μm than the developing device. 6. The development according to claim 1, wherein the developer regulating member has both end portions and a center portion in the longitudinal direction fixed to attachment portions in the developing device. apparatus. The developing device according to claim 1, wherein the developer regulating member is disposed to face the developing roller at an upper position. The developing device according to claim 1, wherein the sleeve of the developing roller is made of aluminum. In the magnet, the range in the longitudinal direction of the magnetic pole formed at a position facing or near the developer regulating member includes the range in the longitudinal direction of the magnetic member of the developer regulating member. The developing device according to claim 1, wherein the developing device is configured as described above. A process cartridge that is detachably installed on the main body of the image forming apparatus,
10. A process cartridge in which the developing device according to claim 1 and the image carrier are integrated. An image forming apparatus comprising the developing device according to claim 1 and the image carrier.

Images