JP2011002562A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of reducing the cost, simplifying the mechanism and solving various problems, and to provide a process cartridge that use the developing device and an image forming apparatus (including a color image forming apparatus).SOLUTION: The developing device includes a developer carrier supplying a two-component developer, comprising a toner and a carrier to a latent image carrier and a developer-stirring and conveying means for stirring and conveying the two-component developer comprising the toner and the carrier and makes an electrostatic latent image on the latent image carrier visible. In the developing device, the developer stirring and conveying means constitutes an endless conveying member.

Description

  The present invention relates to a developer carrying member and a developing device that develops an electrostatic latent image with a two-component developer composed of a toner and a carrier, a process cartridge having the developing device, and an image forming apparatus.

A developing device having a conveying screw provided for stirring, conveying and circulating the developer is well known.
With respect to these developing devices, the developer movement direction is substantially the same in the two openings communicating with the developer conveyance path formed on both ends of the developer conveyance path, which is the developer delivery section at the end of the conveyance screw. Since it changes at a right angle, the flow of the developer becomes worse, and there is a problem that the developer stays.
In particular, in recent years, there has been a trend toward downsizing of the developing device, and in the conveying screw type developing device arranged above and below, in addition to the above problems, the side of conveying the developer against the gravity direction (lifting up) is also provided. As a result, the occurrence of stagnation became more prominent.
The following items become new problems due to the occurrence of the retention of the developer.
・ Torque increase due to developer retention ・ Developer agglomerates due to heat and pressure near the developer retention part (near the transport screw bearing) ・ White due to the agglomeration between the development roller and blade Abnormal image generation such as streaks ・ Insufficient stirring due to retention of developer ・ Insufficient stirring causes abnormal image generation such as density unevenness due to non-uniformity of toner density, charge amount, etc. For the purpose of preventing the developer from staying at the downstream end in the direction, the invention of Japanese Patent Application Laid-Open No. 2006-003524 is known. However, this invention has the disadvantages that the developing device becomes large and the cost is high.
In addition, in a developing device having a conveying screw arranged above and below, an invention is proposed in which the developer is lifted using a magnet roller, scooping means, developer conveying member, etc. as described in Patent Documents 2 to 4 etc. However, there are disadvantages such as an increase in cost or a complicated mechanism due to the addition of another member.

  The present invention has been invented in view of the above problems, and by constituting the developer conveying means with an endless conveying member, cost reduction and simplification of the mechanism can be achieved, and the various problems described above can be solved. An object is to provide a developing device, a process cartridge using the developing device, and an image forming apparatus (including a color image forming apparatus).

In order to solve the above-described problems, the present invention has the following solutions.
According to the first aspect of the present invention, there is provided a developer carrying member for supplying a two-component developer comprising a toner and a carrier to the latent image carrier, and development for stirring and conveying the two-component developer comprising the toner and the carrier. And a developer agitating / conveying means, wherein the developer agitating / conveying means comprises an endless conveying member. The developing device visualizes the electrostatic latent image on the latent image carrier.
According to a second aspect of the present invention, in the developing device according to the first aspect, the developer conveying means is a belt-like member having a plurality of convex portions.
Further, the invention according to claim 3 is the developing device according to claim 1, wherein the developer conveying means is a belt-like member having a plurality of convex portions, and the convex portions are inclined in the traveling direction. It is characterized by being.
According to a fourth aspect of the present invention, in the developing device according to the first aspect, the developer conveying means is a belt-shaped member having a plurality of convex portions and the convex portions having slits. Features.
Further, the invention according to claim 5 is the developing device according to claim 1, wherein the developer conveying means is a belt-like member having a plurality of convex portions, and the convex portions randomly having slits. It is characterized by that.
A sixth aspect of the present invention is a process cartridge including the developing device according to any one of the first to fifth aspects.
According to a seventh aspect of the invention, there is provided a developing device according to any one of the first to fifth aspects, or an image forming apparatus provided with the process cartridge according to the sixth aspect.
According to an eighth aspect of the present invention, there is provided a color image forming apparatus including a developing device according to any one of the first to fifth aspects or a plurality of process cartridges according to the sixth aspect.

By constituting the developer conveying means with an endless conveying member, the cost can be reduced and the mechanism can be simplified, and the following merits can be obtained.
・ Preventing developer retention ・ Preventing torque increase due to smooth developer flow ・ Preventing aggregates due to smooth developer flow ・ Preventing abnormal images such as white streaks due to aggregate prevention・ Prevents insufficient agitation due to smooth developer flow ・ Prevents abnormal images such as density unevenness due to insufficient agitation ・ Prevents unevenness in screw pitch by not using a conveying screw

1 is a diagram illustrating a schematic configuration of an image forming apparatus (printer) according to the present invention. It is a figure which shows schematic structure of the conventional process cartridge. It is the perspective view which decomposed | disassembled the conventional image development apparatus 5 (5Y). It is sectional drawing which shows the structure of the conventional image development apparatus 5 (5Y). It is sectional drawing of the SS line | wire of FIG. It is sectional drawing which shows the structure of the developing apparatus 5 (5Y) of this invention. It is a perspective view which shows the structure of the stirring conveyance means which is the principal part of the image development apparatus 5 (5Y) of this invention. It is a perspective view which shows the structural example of the stirring conveyance means of the principal part of the developing apparatus 5 (5Y) of this invention. It is an expansion perspective view which shows the example of the stirring conveyance means of the principal part of the developing apparatus 5 (5Y) of this invention. It is an expansion perspective view which shows the example which provided the slit 83Y in the convex part 82Y of the belt-shaped member shown in FIG. It is an expansion perspective view which shows the structure which formed the slit 83Y diagonally in the convex part 82Y of the belt-shaped member shown in FIG. FIG. 9 is an enlarged perspective view showing a configuration in which slits 83Y are randomly formed in the convex portions 82Y of the belt-like member shown in FIG.

Hereinafter, the present invention will be described in detail with reference to the drawings.
As an example of an embodiment of an image forming apparatus to which the present invention is applied, an electrophotographic printer (hereinafter simply referred to as a printer) will be described. The image forming unit will be described as a process cartridge. The process cartridge is a cartridge in which at least one of a charging unit, a developing unit, and a cleaning unit and an electrophotographic photosensitive member are integrally configured so as to be detachable from the image forming apparatus main body.
First, the basic configuration of the printer will be described. FIG. 1 is a schematic configuration diagram of the printer.
In FIG. 1, a printer 100 includes four process cartridges 6 (6Y, 6M, 6C, and 6K) for generating yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and K) toner images. It has. These use Y, M, C, and K toners of different colors, but other than that, they have the same configuration, and are replaced when the lifetime is reached. Taking a process cartridge 6Y for generating a Y toner image as an example, as shown in FIG. 2, a drum-shaped photosensitive member 1Y, a drum cleaning device 2Y, a charge eliminating device (not shown), a charging device 4Y, a developing device 5Y, etc. I have.

The process cartridge 6Y can be attached to and detached from the main body of the printer 100 so that consumable parts can be replaced at a time. The charging device 4Y uniformly charges the surface of the photoreceptor 1Y that is rotated clockwise in the drawing by a driving unit (not shown). The uniformly charged surface of the photoreceptor 1 </ b> Y is exposed and scanned by the laser beam L to carry an electrostatic latent image for Y. This Y electrostatic latent image is developed into a Y toner image by the developing device 5Y using Y toner. Then, intermediate transfer is performed on the intermediate transfer belt 8. The drum cleaning device 2Y removes the toner remaining on the surface of the photoreceptor 1Y after the intermediate transfer process. The static eliminator neutralizes residual charges on the photoreceptor 1Y after cleaning. By this charge removal, the surface of the photoreceptor 1Y is initialized and prepared for the next image formation.
In the other process cartridges 6M, 6C, and 6K, M, C, and K toner images are similarly formed on the photoreceptors 1M, 1C, and 1K, and are intermediately transferred onto the intermediate transfer belt 8. In FIG. 1, the exposure device 7 is disposed below the process cartridges 6Y, 6M, 6C, and 6K. The exposure apparatus 7 serving as a latent image forming unit irradiates the photosensitive members 1Y, 1M, 1C, and 1K in the process cartridges 6Y, 6M, 6C, and 6K with a laser beam L emitted based on the image information. By this exposure, electrostatic latent images for Y, M, C, and K are formed on the photoreceptors 1Y, 1M, 1C, and 1K. The exposure device 7 irradiates the photoconductor 1 through a plurality of optical lenses and mirrors while scanning laser light (L) emitted from a light source with a polygon mirror rotated by a motor.

In the lower side of the exposure apparatus 7 in FIG. 1, paper supply means 26 including a paper storage cassette 26 for storing paper P as a recording medium, a paper supply roller 27 incorporated therein, a registration roller pair 28, and the like are disposed. Yes. The paper storage cassette 26 stores a plurality of transfer papers P as recording bodies, and a paper feed roller 27 is in contact with each uppermost transfer paper P. When the paper feeding roller 27 is rotated counterclockwise in the drawing by a driving means (not shown), the uppermost transfer paper P is fed toward the rollers of the registration roller pair 28.
The registration roller pair 28 rotationally drives both rollers to sandwich the transfer paper P, but temporarily stops rotating immediately after sandwiching. Then, the transfer paper P is sent out toward a later-described secondary transfer nip at an appropriate timing. In the sheet feeding unit having such a configuration, a conveying unit is configured by a combination of the sheet feeding roller 27 and the registration roller pair 28 corresponding to the timing roller. This transport means transports the transfer paper P from a paper storage cassette 26 serving as a storage means to a secondary transfer nip described later.
Above the process cartridges 6Y, 6M, 6C, and 6K in FIG. 1, an intermediate transfer unit 15 that moves the intermediate transfer belt 8 as an intermediate transfer member endlessly while stretching is disposed. In addition to the intermediate transfer belt 8, the intermediate transfer unit 15 includes four primary transfer bias rollers 9Y, 9M, 9C, and 9K, a cleaning device 10, and the like. A secondary transfer backup roller 12, a cleaning backup roller 13, a tension roller 14 and the like are also provided.

The intermediate transfer belt 8 is endlessly moved in the counterclockwise direction in the figure by the rotational drive of at least one of the rollers while being stretched around these three rollers. The primary transfer bias rollers 9Y, 9M, 9C, and 9K sandwich the intermediate transfer belt 8 that is moved endlessly in this manner from the photoreceptors 1Y, 1M, 1C, and 1K to form primary transfer nips, respectively. Yes. In these methods, a transfer bias having a polarity opposite to that of toner (for example, plus) is applied to the back surface (loop inner peripheral surface) of the intermediate transfer belt 8. All the rollers except the primary transfer bias rollers 9Y, 9M, 9C, and 9K are electrically grounded.
The intermediate transfer belt 8 sequentially passes through the primary transfer nips for Y, M, C, and K along with the endless movement thereof, and Y, M, and C on the photoreceptors 1Y, 1M, 1C, and 1K. , K toner images are superimposed and primarily transferred. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the intermediate transfer belt 8. The secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 between the secondary transfer roller 19 and forms a secondary transfer nip. The four-color toner image formed on the intermediate transfer belt 8 is transferred to the transfer paper P at the secondary transfer nip.

Transfer residual toner, which is toner that has not been transferred to the transfer paper P, adheres to the intermediate transfer belt 8 after passing through the secondary transfer nip. This is cleaned by the cleaning device 10. In the secondary transfer nip, the transfer paper P is sandwiched between the intermediate transfer belt 8 whose surface moves in the forward direction and the secondary transfer roller 19 and conveyed in the direction opposite to the registration roller pair 28 side. When the transfer paper P sent out from the secondary transfer nip passes between the rollers of the fixing device 20, the four-color toner image transferred to the surface is fixed by heat and pressure. Thereafter, the transfer paper P is discharged out of the apparatus through a pair of paper discharge rollers 29.
A stack unit 30 is formed on the upper surface of the printer body, and the transfer paper P discharged outside the apparatus by the discharge roller pair 29 is sequentially stacked on the stack unit 30. Note that toner bottles 32Y, 32M, 32C, and 32K for the respective colors are provided below the stack unit 30. Reference numeral 31 denotes a toner bottle holder. As the image forming apparatus of the present invention, a conventional apparatus can be used except that the developing apparatus of the present invention to be described later is provided or a plurality of process cartridges having the developing apparatus of the present invention are provided.

Returning to FIG. 2 again, the configuration of the developing device 5Y in the conventional process cartridge 6Y will be described.
The developing device 5Y includes a magnetic field generating means inside, a developing roller 51Y as a developer carrying member that carries and conveys a two-component developer containing magnetic particles and toner, and is carried on the developing roller 51Y. And a doctor 52Y as a developer regulating member that regulates the layer thickness of the conveyed developer. Here, a place where the developing roller 51Y is accommodated is a first chamber 53Y.
Further, the place where the developer is accommodated is a second chamber 54Y, and a toner conveying screw (conveying body) 55Y (first member) for agitating and conveying the toner (as a developer conveying means) in the second chamber 54Y. A conveying screw 55Ya, a second conveying screw 55Yb), a toner supply port 58Y for taking the toner into the second chamber 54Y, and a communication port 59Y between the first chamber 53Y.
Above the toner supply port 58Y, there are provided a shutter 71Y for closing the toner supply port 58Y and a toner supply port case 72Y that holds the shutter 71Y and is provided so as to cover the toner supply port 58Y.
Here, reference numeral 56Y denotes a density detection sensor for detecting the toner density of the developer. When the density detection sensor 56Y detects a lack of toner density in the second chamber 54Y, a replenishment signal from the control unit 57Y. As a result, the drive motor 41Y rotates and the toner bottle 32Y rotates to replenish toner. Further, the developing device 5Y is largely formed by a first member 75Y (upper case) including the inner wall of the first chamber 53Y and a second member 76Y (lower case) including the inner wall of the second chamber 54Y.

FIG. 3 is an exploded perspective view of a conventional developing device 5Y.
The second chamber 54Y including the toner conveying screw 55Y is also divided into 54Ya including the first conveying screw 55Ya and 54Yb including the second conveying screw 55Yb, with the partition wall 61Y as a boundary. Here, the second chambers 54Ya and 54Yb divided into two are connected via openings 62Ya and 62Yb located at both ends of the partition wall 61Y, and the developer passes through the openings 62Ya and 62Yb. 54Ya and 54Yb in the second room 54Y are circulated. Note that 54Ya and 54Yb in which the developer circulates are referred to as a developer conveyance path. (Arrow is the direction of circulation)
Further, the circulation of the developer is performed by the first conveying screw 55Ya and the second conveying screw 55Yb described above, and the conveying screw 55Y is assembled to the second member 76Y (lower case) by the bearing 65Y.
Here, the drive-side bearing of the first conveying screw 55Ya is 65Ya, the driven-side bearing is 65Yb, the driving-side bearing of the second conveying screw 55Yb is 65Yc, and the driven-side bearing is 65Yd.

FIG. 4 is a cross-sectional view showing a configuration of a conventional developing device 5 (5Y), and FIG. 5 is a diagram in which the cross section taken along the line S-S in FIG. However, the same parts as described above are indicated by the same numbers as above.
The developer in the developing device 5Y is conveyed by two different developer circulation paths.
The first developer circulation path is a circulation path according to arrows C → D → E → F → C shown in FIG. The developer conveyance of the arrows C and E is performed by rotation of the second conveyance screw 55Yb and the first conveyance screw 55Ya, respectively. Further, the developer conveyance of the arrow D is performed by lifting the developer from the second conveyance screw 55Yb side against the gravity to the first conveyance screw 55Ya side, and the conveyance of the arrow F is a gravity drop.
In the second developer circulation path, as shown by an arrow G, the developer is replenished to the developing roller 51Y from the first conveying screw 55Ya side, and sent to the second conveying screw 55Yb side via the developing roller 51Y. (See FIG. 4).

[Embodiment (Developing Device)]
The developing device of the present invention will be described below.
First, FIG. 6 is a diagram showing an example of the developing device of the present invention.
In the present invention, description will be given using the developing device 5Y that has a developer transport path at the top and bottom, which is considered to be prone to developer stagnation, but there are at least two developer transport paths other than two at the top and bottom. The present invention is also effective in the developing device 5Y having a horizontal or substantially horizontal developer conveyance path.
In the present invention, an endless conveying member 80 (80Y) is provided as a developer stirring and conveying means in place of the conventionally used conveying screw 55Y. Such an endless conveying member may be any of a belt-like member, an auger-like member, and a screw-like member.
First, an example in which a belt-like member is used as an endless conveying member as a developer stirring and conveying means used in the developing device of the present invention will be described.
In the present invention, instead of the conventionally used conveying screw 55Y, a belt-like member 80Y having a plurality of convex portions 82Y is provided. The belt-shaped member 80Y has a configuration in which a plurality of convex portions 82Y are provided on a belt portion (belt base portion) 81Y.
Here, by providing the belt-shaped member 80Y, two belt screws 80Y are conventionally required, whereas only one belt-shaped member 80Y is required. For this reason, the cost can be reduced, and the merit that the problem is less likely to be generated by simplifying the mechanism can be obtained.

FIG. 7 is a perspective view of the developing device 5Y of FIG. In order to facilitate understanding of the mechanism, the photoconductor 1Y, the doctor 52Y, the case, and the like are omitted.
The developer is conveyed in the direction of the arrow in FIG. 85Y is a member for driving the belt-shaped member 80Y, and 86Y is a driven member (the driving member 85Y and the driven member 86Y may be reversed).
In order to drive the belt-shaped member 80Y, for example, the belt base member 81Y may use friction such as a V belt, a round belt, or a flat belt, or may be a toothed transmission belt such as a timing belt. Absent.
As described above, by using the belt-like member as the developer stirring and conveying means, the flow of the developer becomes smooth, and the following effects are obtained.
・ Prevents stagnation due to smooth developer flow ・ Prevents torque increase due to smooth developer flow ・ Prevents aggregate formation due to smooth developer flow ・ White due to aggregate prevention Prevention of abnormal images such as streaks ・ Prevents insufficient stirring due to smooth developer flow ・ Prevents abnormal images such as density unevenness due to insufficient stirring ・ Prevents unevenness of screw pitch due to non-use of conveying screw

FIG. 8 is a perspective view of a single belt-shaped member 80Y used as the developer conveying means, and FIGS. 9 to 12 are diagrams showing other embodiments.
In addition, regarding other embodiment, it has shown in the form which paid its attention to the A section of the belt-shaped member 80Y of FIG.
FIG. 9 shows the convex portion 82Y having an inclination with respect to the traveling direction. Due to this inclination, when the developer is conveyed, the supply of the developer to the developing roller 51Y side is further improved.
FIG. 10 shows the belt-like member shown in FIG. 8 with a slit 83Y on the convex portion 82Y. The slit 83Y is formed straight with respect to the belt portion 81Y.
By providing the slit 83Y in this manner, the developer transport speed varies from place to place during developer transport (because there is a difference in transport speed), the shear is applied to the developer and the agitation is improved. .

FIG. 11 is a diagram illustrating a configuration in which the slits 83Y are formed obliquely, and FIG. 12 is a diagram illustrating a configuration in which the slits 83Y are randomly formed.
Stirability is further improved by providing the slits 83Y obliquely or randomly from the straight.
In the present invention, the developer is transported and stirred by the belt-shaped member 80Y and supplied to the developing roller 51Y. However, as the developer stirring and transporting means used in the present invention, a stirring member or a supply member is used. May be provided separately and used together with the belt-shaped member 80Y.
At this time, as the stirring member or the supply member, a paddle-shaped rotating member having flat blades is considered good.

  The example of the above embodiment has been described mainly with respect to the developing device alone, but the same invention can be implemented with a process cartridge using a developing device equipped with the present invention. Naturally, a developing device, an image forming device using a process cartridge, or a color image forming device using a plurality of developing devices and a plurality of process cartridges are also possible and can be sufficiently understood from the above description. Therefore, further explanation is omitted. Note that a belt-like member is used as the developer agitating and conveying means 80, and the developer is intruded inside the drive unit (on the side of the belt-like member on which the developer is conveyed, not on the conveying surface side). Means to prevent can be provided.

  1 image carrier (photosensitive drum), 1Y image carrier for yellow (photosensitive drum for yellow), 1M image carrier for magenta (photosensitive drum for magenta), 1C image carrier for cyan (photosensitive drum for cyan) ) 1K black image carrier (photosensitive drum for black), 5 developing device (5Y yellow developing device, 5M magenta developing device, 5C cyan developing device, 5K black developing device)), 6 process cartridge ( 6Y yellow process cartridge, 6M magenta process cartridge, 6C cyan process cartridge, 6K black process cartridge), 51 developer carrier, 80 belt-like member (80Y yellow belt-like member), 81 belt base, 81Y yellow Belt base, 82 convex (82Y Y convex ), 83 slits (83Y for yellow slits) 85 belt-shaped member of the drive member, a driven member 86 belt-shaped member

JP 2006-003524 A JP 2000-181231 A JP 2002-365909 A Patent No. 4093677

Claims (8)

A developer carrying member for supplying a two-component developer comprising a toner and a carrier to a latent image carrier, and a developer stirring and conveying means for stirring and conveying the two-component developer comprising the toner and a carrier, In the developing device for visualizing the electrostatic latent image on the latent image carrier,
The developing device, wherein the developer agitating / conveying means comprises an endless conveying member.   2. The developing device according to claim 1, wherein the developer conveying means is a belt-like member having a plurality of convex portions.   The developing device according to claim 1, wherein the developer conveying unit is a belt-like member having a plurality of convex portions, and the convex portions are inclined in the traveling direction.   The developing device according to claim 1, wherein the developer conveying unit is a belt-shaped member having a plurality of convex portions and the convex portions having slits.   2. The developing device according to claim 1, wherein the developer conveying unit is a belt-like member having a plurality of convex portions, and the convex portions randomly have slits.   A process cartridge comprising the developing device according to claim 1.   An image forming apparatus comprising the developing device according to claim 1 or the process cartridge according to claim 6.   A color image forming apparatus comprising a plurality of the developing devices according to claim 1 or a plurality of process cartridges according to claim 6.

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