JP3832242B2 - Development device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to electrophotographic image forming such as a printer, a copying machine, and a facsimile machine that visualizes an electrostatic latent image formed on an image carrier such as a photosensitive drum or a photosensitive belt by attaching toner. The present invention relates to a developing device used in the apparatus.
[0002]
[Prior art]
As this type of developing device, for example, a developing device described in Japanese Patent Laid-Open No. 4-199164 is known. In this developing device, a plurality of developing devices are arranged around the rotation axis of the developing device holding means (rotating support) provided in the vicinity of the image carrier (photosensitive drum) from the viewpoint of reducing the size of the device. Configured. More specifically, the developing device includes a developing unit having toner of each color of yellow (Y), magenta (M), cyan (C), and black (K) along the circumferential direction of the developing unit holding unit. Each developing device uses a developing roller that performs development by forming a toner layer on the surface and bringing it into contact with the image carrier, and a supply roller that supplies the toner in the developing device to the developing roller. Configured.
[0003]
[Problems to be solved by the invention]
However, in the above prior art, in order to stir the toner in the developing device, a stirring means (agitator) configured to forcibly rotate in the developing device is provided. A problem has arisen.
[0004]
According to the conventional technique, the stirring means is forcibly rotated in the developing device using a motor or the like, and the toner is stirred by the forcible rotational driving force of the stirring means. Therefore, there is a problem that the toner is subjected to stress more than necessary during the stirring, and the deterioration of the toner proceeds.
[0005]
Further, in the prior art, in order to stir the toner as described above, a driving means such as a motor for rotating the stirring means is required. Therefore, there is a problem that parts for constituting the driving means are required, and the apparatus becomes complicated, and it is difficult to shorten the assembly time of the apparatus and downsize the apparatus. Furthermore, when the apparatus becomes complicated and takes time to assemble the apparatus, there is a problem that the cost increases.
[0006]
Accordingly, the present invention has been made to solve such a problem, and by providing a toner agitation unit capable of agitating the toner without using a driving unit, the deterioration of the toner is prevented, and It is an object of the present invention to provide a developing device that can reduce the number of parts, reduce the size of the device, reduce costs, and the like.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is provided with a plurality of developing units that develop a latent image formed on an image carrier with toner, and a plurality of developing units that are rotatably provided around a predetermined rotation axis. Developing device holding means for holding the devices arranged in the rotation direction, and selectively positioning one of the plurality of developing devices as the image carrier by rotating and positioning the developing device holding means. A developing device that is disposed opposite to a body and performs toner development of a latent image by the developing unit, each developing unit including a housing that forms a toner containing portion that contains toner therein, and a toner containing portion that is contained in the toner containing portion A toner carrier that transports a portion of the toner that has been transported to a development position facing the image carrier, and a toner container that is rotatably supported with respect to the housing. And a toner agitating means for agitating the toner in the toner accommodating portion by rotating relative to the housing that moves concentrically around the rotation axis as the holding means rotates. It is a feature.
[0008]
According to the developing device configured as described above, since the toner agitating unit is rotatably supported with respect to the housing, the toner agitating unit is concentrically formed around the rotation axis as the developing device holding unit rotates. As the housing moves, the toner stirring means rotates relative to the housing. That is, the developing device according to the present invention can relatively rotate the toner agitating means in the housing without using a motor or the like for driving the toner agitating means. Therefore, according to this configuration, the toner accommodated in the housing can be appropriately agitated by the toner agitating means, so that the toner is not deteriorated without applying unnecessary stress to the toner during agitation. It becomes possible to prevent progress. Further, since driving means such as a motor for rotating the toner agitation means is not required, the number of parts, the assembly time, the size of the apparatus, and the cost can be reduced when forming the developing device. Can do.
[0009]
The toner agitating means includes a support shaft portion disposed substantially parallel to a rotation axis of the rotation shaft and having both ends pivotally supported with respect to the housing; and the support shaft portion And a balancer provided on at least one of the support shaft and the agitation unit, and the center of gravity of the balancer is located below the axis of the support shaft in the vertical direction. The stirring unit is held in a predetermined posture.
[0010]
According to such a configuration, the eccentric load of the balancer acts on the lower side in the vertical direction, and even if the housing moves concentrically around the rotation axis as the developing device holding means rotates. Since the posture of the stirring unit in the vertical direction is maintained, the toner stirring unit that rotates relatively in the housing can be easily realized.
[0011]
The toner agitating means includes a support shaft portion disposed substantially parallel to a rotation axis of the rotation shaft and having both ends pivotally supported with respect to the housing; and the support shaft portion A stirring portion provided on the support shaft portion, wherein the stirring portion has at least one stirring piece attached to the support shaft portion, and the center of gravity of the at least one stirring piece is an axis of the support shaft portion Alternatively, the stirring unit may be configured to be positioned at a lower position in the vertical direction than the predetermined direction.
[0012]
According to such a configuration, the eccentric load of at least one stirring piece whose center of gravity is shifted acts on the lower side in the vertical direction, and the housing rotates the rotation shaft with the rotation of the developing device holding means. Even if it moves concentrically to the center, since the posture of the stirring portion in the vertical direction is maintained, the toner stirring means that rotates relatively in the housing can be easily realized without providing a balancer or the like. be able to.
[0013]
In addition, the agitation part includes at least one first inclined agitation piece attached to the support shaft part so as to be inclined from a substantially central part of the support shaft part to one end part, and an abbreviation of the support shaft part. And at least one second inclined stirring piece that is attached to the support shaft portion while being inclined from the center portion toward the other end portion, and the stirring portion is held in the predetermined posture. The surface normal of the inclined upper surface of the first inclined stirring piece forms an acute angle with respect to the first imaginary line extending from the attachment position of the inclined stirring piece toward the one end, and the second inclined stirring piece It is preferable that the surface normal of the inclined upper surface forms an acute angle with respect to the second imaginary line extending from the attachment position of the inclined stirring piece toward the other end.
[0014]
According to this preferable configuration, the toner agitating means relatively rotates within the housing, so that the toner that contacts the first and second inclined agitating pieces is separated from the substantially central portion of the support shaft portion at each end. It will be transferred in the direction of the part. That is, according to such a configuration, it is possible to easily feed the toner in the longitudinal direction of the support shaft, which is relatively difficult.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a view showing an image forming apparatus equipped with an embodiment of a developing device according to the present invention. In this image forming apparatus, a photoconductor 2 is provided in the apparatus main body 1 so as to be rotatable in an arrow direction D1 in FIG. Around the photosensitive member 2, a charger 3 as a charging unit, a rotary developing unit 4 as a developing unit, and a cleaning unit 5 are arranged along the rotation direction D1. The charger 3 is applied with a charging bias from a charging bias circuit (not shown), and uniformly charges the outer peripheral surface of the photoreceptor 2.
[0016]
Then, laser light L is irradiated from the exposure unit 6 toward the outer peripheral surface of the photosensitive member 2 charged by the charger 3. The exposure unit 6 scans and exposes the photosensitive member 2 with a laser beam L in accordance with image data obtained by developing the image formation command and develops an electrostatic latent image corresponding to the image formation command on the photosensitive member 2. Form.
[0017]
The electrostatic latent image thus formed is developed with toner by the developing unit 4. That is, in this embodiment, as the developing unit 4, a yellow developing unit 4Y, a cyan developing unit 4C, a magenta developing unit 4M, and a black developing unit 4K are provided to be rotatable about an axis. . These developing units 4Y, 4C, 4M, and 4K are rotationally positioned and selectively abut against the photoreceptor 2 to apply toner to the surface of the photoreceptor 2. As a result, the electrostatic latent image on the photoreceptor 2 is visualized with the selected toner color. The configuration and operation of the developing unit 4 will be described in detail later.
[0018]
The toner image developed by the developing unit 4 as described above is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer region TR1. A cleaning unit 5 is disposed at a position where the photoconductor 2 advances in the circumferential direction (rotation direction D1 in FIG. 1) from the primary transfer region TR1, and the cleaning unit 5 is arranged on the outer periphery of the photoconductor 2 after the primary transfer. Scrape off any toner remaining on the surface.
[0019]
The transfer unit 7 includes an intermediate transfer belt 71 that is stretched around a plurality of rollers, and a drive unit (not shown) that drives the intermediate transfer belt 71 to rotate. When a color image is transferred to the sheet member S, each color toner image formed on the photosensitive member 2 is superimposed on the intermediate transfer belt 71 to form a color image, and a predetermined secondary transfer region. In TR2, the color image is secondarily transferred onto the sheet member S taken out from the cassette 8. The sheet member S on which the color image is formed in this way is conveyed to the discharge tray portion 11 provided on the upper surface portion of the apparatus main body 1 via the fixing unit 9.
[0020]
Next, the configuration and operation of the rotary developing unit 4 provided in the image forming apparatus of FIG. 1 will be described in detail. FIG. 2 is a partially enlarged view of the rotary developing unit of FIG. As shown in FIG. 1, the rotary developing unit 4 has a rotating shaft 4a at its center and a support frame 4b fixed to the rotating shaft 4a. The four color developing devices 4Y and 4C described above are used. , 4M, 4K are fixed radially to the support frame 4b around the rotation shaft 4a by fixing brackets (not shown). Further, a drive unit (not shown) is connected to the rotary shaft 4a via a clutch. By driving the drive unit, the support frame 4b is rotated, and the four developing devices 4Y, 4C, 4M, and 4K are rotated. One developing device can be selectively positioned at a developing position DP (FIG. 2) opposed to the photosensitive member 2. Thus, in this embodiment, the support frame 4b corresponds to the “developer holding unit” of the present invention.
[0021]
The developing devices 4Y, 4C, 4M, and 4K held by the support frame 4b have the same configuration. Therefore, here, the configuration of the developing device 4Y shown in FIG. 2 will be described in detail, and the description of the configuration of the other developing devices 4C, 4M, and 4K will be omitted.
[0022]
In the developing device 4Y, two housing members 41 and 42 are integrally combined to form a housing 43 serving as a main body of the developing device 4Y. Since the toner is stored in the housing 43, the toner storage space inside the housing 43 becomes the toner storage portion 44.
[0023]
A supply roller 46 is disposed in the toner storage portion 44 and rotates while being in contact with a developing roller 47 that is rotationally driven on the most distal side of the housing 43. The developing roller 47 carries the toner supplied from the supply roller 46 and rotates while being in contact with the photosensitive member 2, and causes the toner to adhere to the surface of the photosensitive member 2 at the developing position DP (FIG. 2). In this way, the yellow toner is rubbed against the surface of the developing roller 47, and a toner layer having a predetermined thickness (for example, several hundred μm) is formed on the surface of the developing roller 47. In this embodiment, the developing roller 47 functions as the “toner carrier” of the present invention.
[0024]
Further, a regulating blade 48 is disposed at a contact position CP (FIG. 2) between the contact position CP (FIG. 2) between the supply roller 46 and the development roller 47 and the development position DP. The regulation blade 48 includes a plate-like member 481 such as stainless steel or copper, and an elastic member 482 such as a rubber or a resin member attached to the tip of the plate-like member 481. The rear end portion of the plate-like member 481 is fixed to the housing member 41, and the elastic member 482 is in elastic contact with the surface of the developing roller 47 at the contact position EP. In this embodiment, the thickness of the toner layer formed on the surface of the developing roller 47 is finally restricted to about 100 μm by the restriction blade 48 configured as described above, and at this time, the toner is caused by friction with the restriction blade 48. Are charged to the same polarity. In this way, the toner charged to a predetermined polarity with respect to the developing roller 47 is supplied to the developing position DP, and the electrostatic latent image on the photoreceptor 2 can be developed with the toner on the developing roller 47.
[0025]
In addition, a toner stirring mechanism 49 that rotates relative to the housing 43 is provided in the housing 43 without using drive means or the like. Here, FIG. 3 is a schematic view showing a mounting state of the toner agitating mechanism 49 in the housing 43. Specifically, the housing 43, the supply roller 46, the developing roller 47, as viewed from the direction of arrow A in FIG. 4 is a schematic diagram showing the positional relationship of the toner stirring mechanism 49 and the like. In FIG. 3, in order to avoid complication of the drawing, the description of the components other than the supply roller 46, the developing roller 47, and the toner stirring mechanism 49 is omitted in principle, and the housing 43 is omitted. The shape of only the outer frame is indicated by a virtual line (two-dot chain line). FIG. 4 is a schematic perspective view of the toner stirring mechanism 49. In this embodiment, the toner stirring mechanism 49 functions as the “toner stirring unit” of the present invention.
[0026]
As shown in FIGS. 2 to 4, the toner stirring mechanism 49 has a support shaft portion 491 having a longitudinal direction in the direction of the rotation axis of the rotation shaft 4 a and provided substantially parallel to the direction of the rotation axis. The agitation part 492 having a plurality of agitation pieces 492a and 492b attached to the support shaft part 491, and the balancer 493 attached to both ends 491a and 491b of the support shaft part 491, respectively.
[0027]
Here, both end portions 491 a and 491 b of the support shaft portion 491 are respectively supported by using bearings 421 (for example, radial ball bearings) provided on the outer surface side of the housing member 42, and are rotatable with respect to the housing 43. It is configured.
[0028]
The stirring portion 492 includes a first inclined stirring piece 492a that is attached to the support shaft portion 491 so as to be inclined from the substantially central portion 491c of the support shaft portion 491 toward the one end portion 491a, and the support shaft portion 491. The second inclined stirring piece 492b is attached to the support shaft portion 491 so as to be inclined from the central portion 491c toward the other end portion. More specifically, in the first inclined stirring piece 492a, the surface normal line Fa (FIG. 3) of the inclined upper surface of the first inclined stirring piece 492a is one of the support shaft portions 491 from the mounting position of the first inclined stirring piece 492a. It is attached to the support shaft portion 491 so as to form an acute angle θa (FIG. 3) with respect to the first imaginary line Ha (FIG. 3) extending toward the end portion 491a, and the second inclined stirring piece 492b The surface normal Fb (FIG. 3) of the inclined upper surface of the stirring piece 492b extends to the second imaginary line Hb (FIG. 3) extending from the mounting position of the second inclined stirring piece 492b toward the other end 491b of the support shaft portion 491. It is attached to the support shaft portion 491 so as to form an acute angle θb (FIG. 3).
[0029]
Each balancer 493 is provided on the support shaft portion 491 so as to maintain the posture of the stirring portion 492 provided on the support shaft portion 491 in a predetermined state. Specifically, the two balancers 493 are attached to the support shaft portion 491 so that the center of gravity of each balancer 493 is positioned below the axis of the support shaft portion 491 in the vertical direction. An eccentric load is applied to the same direction (vertical downward direction B (FIG. 3)) of the supported support shaft portion 491. The posture of the toner stirring mechanism 49 in which the stirring unit 492 is maintained in the state shown in FIGS. 2 and 3 by the action of the balancer 493 is hereinafter referred to as “basic posture”.
[0030]
The toner stirring mechanism 49 is configured as described above, and the rotary developing unit 4 is configured using a plurality of developing devices 4Y, 4C, 4M, and 4K having the toner stirring mechanism 49 in the housing 43 (FIG. 1). ). The rotary developing unit 4 rotates the rotary developing unit 4 by 90 degrees about the rotation shaft 4a every time the toner color is switched, and the toner stirring mechanism 49 is configured as described above. As the toner rotates, the toner stirring mechanism 49 rotates relative to the housing 43 that moves concentrically around the rotating shaft 4a, so that the toner in the housing 43 is stirred. This will be specifically described below with reference to FIG.
[0031]
FIG. 5 is a diagram showing an operating state of the toner stirring mechanism 49. Specifically, FIG. 5 shows the movement of the toner in the developing device 4Y and the toner stirring mechanism 49 when the rotary developing unit 4 rotates around the rotation shaft 4a. As described above, since the developing devices 4Y, 4C, 4M, and 4K constituting the rotary developing unit 4 have the same configuration, only the configuration of the developing device 4Y is shown in FIG. Other configurations of the developing devices 4C, 4M, and 4K are omitted. In addition, regarding the operating state of the toner stirring mechanism 49 in each of the developing devices 4Y, 4C, 4M, and 4K, when each of the developing devices 4Y, 4C, 4M, and 4K is set to the same position (for example, the developing position). Therefore, only the operation state of the toner stirring mechanism 49 in the developing device 4Y will be described here.
[0032]
FIG. 5A shows a state in which the developing unit 4Y for yellow is set at the development position DP with respect to the photoreceptor 2. In this state, the toner in the toner container 44 is sent to the developing roller 47 by the supply roller 46, and a toner layer having a thickness of about 100 μm is formed on the surface of the developing roller 47. However, as described above, the surface of the photoreceptor 2 is developed with the toner T by rotating while contacting. The basic stirring posture of the toner stirring mechanism 49 in the housing 43 of the developing device 4Y is maintained by the action of the balancer 493. Hereinafter, the toner stirring mechanism that maintains the basic posture in a state in which the developing device 4Y is set to the development position DP is referred to as a “toner stirring mechanism 49a in the first basic posture”.
[0033]
Next, in FIG. 5B, the rotary developing unit 4 is rotated by 90 ° in the direction of arrow C around the rotation shaft 4a from the state of FIG. And the development position DP is set. The operation in the developing device 4C is the same as that described with reference to FIG. 5A for the developing device 4Y. The toner stirring mechanism 49 in the housing 43 of the developing device 4Y is operated by the support shaft portion 491 supported by the balancer 493 and the bearing 421 even when the developing device 4Y moves around the rotation shaft 4a. The basic posture is maintained. In other words, the support shaft portion 491 is rotatably supported by the bearing 421, and an eccentric load of the balancer 493 acts on the vertical direction B of the support shaft portion 491. Accordingly, the rotation of the developing device 4Y is accompanied. The toner stirring mechanism 49 swings and its basic posture is appropriately maintained. Hereinafter, the toner stirring mechanism that maintains the basic posture in a state where the developing device 4C is set to the development position DP is referred to as “toner stirring mechanism 49b in the second basic posture”.
[0034]
Next, in FIG. 5C, the rotary developing unit 4 is rotated 90 ° in the direction of arrow C around the rotation shaft 4a from the state of FIG. 5B, and the developing device 4M for magenta becomes the photosensitive member. And the development position DP is set. The operation in the developing device 4M is the same as that described with reference to FIG. 5A for the developing device 4Y. Further, the toner agitating mechanism 49 in the housing 43 of the developing device 4Y has the balancer 493 and the like as described with reference to FIG. 5B even when the developing device 4Y further moves around the rotation shaft 4a. The basic posture is maintained by the action of. Hereinafter, the toner stirring mechanism that maintains the basic posture in a state where the developing device 4M is set to the developing position DP is referred to as a “toner stirring mechanism 49c in the third basic posture”.
[0035]
Next, in FIG. 5D, the rotary developing unit 4 is rotated 90 ° from the state of FIG. 5C about the rotation shaft 4a in the direction of the arrow C, so that the black developing device 4K is the photosensitive member. And the development position DP is set. The operation in the developing device 4K is the same as that described with reference to FIG. 5A for the developing device 4Y. Further, the toner agitating mechanism 49 in the housing 43 of the developing device 4Y has the balancer 493 and the like as described with reference to FIG. 5B even when the developing device 4Y further moves around the rotation shaft 4a. The basic posture is maintained by the action of. Hereinafter, the toner stirring mechanism that maintains the basic posture in a state where the developing device 4K is set to the development position DP is referred to as a “toner stirring mechanism 49d in the fourth basic posture”.
[0036]
As shown in FIG. 5, when the rotary developing unit 4 rotates about the rotation shaft 4a, the toner is developed in the developing device 4Y that moves concentrically around the rotation shaft 4a as the support frame 4b rotates. The stirring mechanism 49 is always maintained in the vertical direction by the action of the balancer 493 and the like, regardless of whether the developing device 4Y is set at the developing position DP or any other position. When the rotary developing unit 4 rotates by 90 °, as shown in FIGS. 5A to 5D, the toner agitating mechanism 49 in the housing 43 is the same as the toner agitating mechanism 49a in the first basic posture. From the state, the toner stirring mechanisms 49b, 49c, and 49d in the second, third, and fourth basic postures are returned to the state of the toner stirring mechanism 49a in the first basic posture again.
[0037]
In the present embodiment, the toner agitation mechanism 49 is configured as described above, and the rotary agitation unit 4 is rotated about the rotation shaft 4a, so that the toner agitation mechanism 49 is mounted on the housing 43 without using any driving means. It can be rotated relatively.
[0038]
Therefore, according to the present embodiment, the toner T accommodated in the housing 43 can be appropriately stirred by the toner stirring mechanism 49 without using a forced rotational driving force. Therefore, it is possible to prevent the toner from progressing without applying more stress than necessary. Further, according to the present embodiment, driving means such as a motor for rotating the toner agitating mechanism 49 is not required, so that the number of parts when configuring the developing device is reduced, the assembling time is shortened, and the apparatus is downsized. And cost reduction of the apparatus can be realized.
[0039]
Further, the stirring unit 492 constituting the toner stirring mechanism 49 according to the present embodiment is configured as shown in FIG. 3, and each stirring piece 492a, 492b is a surface method of the inclined upper surface of each stirring piece 492a, 492b. The support shaft 491 has lines Fa and Fb so that they form acute angles θa and θb with respect to the virtual lines Ha and Hb extending from the mounting positions of the stirring pieces 492a and 492b toward the ends 491a and 491b, respectively. It is attached to. The two balancers 493 are attached to the support shaft portion 491 so that the center of gravity of each balancer 493 is positioned vertically below the shaft center of the support shaft portion 491. The eccentric load of the balancer 493 Thus, the posture of the stirring unit 492 is maintained as shown in FIG. Therefore, according to the present embodiment, the toner T that has come into contact with the stirring portion 492 of the toner stirring mechanism 49 extends from the substantially central portion 491c of the support shaft portion 491 to the end portions along the inclination angle of the stirring pieces 492a and 492b. The toner T is transferred in the directions 491a and 491b, and the stirring of the toner T in the housing 43 is further promoted.
[0040]
Further, in the present embodiment, when the toner T is accommodated in the housing 43 at a predetermined filling rate or less, the degree of freedom of the toner T in the housing 43 is increased, so that the rotary developing unit 4 is rotated. Thus, not only the toner stirring mechanism 49 rotates in the housing 43 but also a part of the toner T comes into contact with the toner stirring mechanism 49 as the rotary developing unit 4 rotates (see FIG. 5). Stirring is further promoted. That is, according to the present embodiment, it is possible to obtain a more appropriate stirring state according to the filling rate of the toner T. According to experiments, the filling rate of the toner T in the housing 43 is about 70% or less. Preferably there is.
[0041]
In the present embodiment, the toner stirring mechanism 49 includes a support shaft portion 491, a stirring portion 492 having first and second inclined stirring pieces 492a and 492b provided on the support shaft portion 491, and a support shaft portion. In the above description, the two balancers 493 provided in 491 are used. However, the present invention is not limited to this configuration, and is held in a predetermined posture regardless of the setting position of the developing device 4Y. In this case, the toner stirring mechanism may have any configuration. Therefore, for example, one balancer may be provided, and an earring-shaped (or eardrop-shaped) balancer may be provided for one or more of the stirring pieces constituting the stirring unit. As shown in FIG. 6, a part of the stirring pieces 492c and 492d constituting the stirring part 492 provided on the support shaft part 491 may be provided so as to function as a balancer. In FIG. 6, the center of gravity of each stirring piece 492c, 492d provided in the vicinity of both end portions 491a, 491b of the support shaft portion 491 is positioned lower than the axis of the support shaft portion 491 in the vertical direction, that is, It is attached to the support shaft portion 491 so as to be in an eccentric state. Therefore, when both end portions 491a and 491b of the support shaft portion 491 are supported by bearings, the toner stirring mechanism 49 is caused by the eccentric load of the stirring pieces 492c and 492d provided near the both end portions 491a and 491b. It will be held in a predetermined posture.
[0042]
In this embodiment, the case where one toner stirring mechanism 49 is provided in the housing 43 has been described. However, the present invention is not limited to this configuration, and a plurality of toner stirring mechanisms 49 may be provided in the housing as necessary. 43 may be provided. Further, in the present embodiment, the case where only the toner stirring mechanism 49 is provided has been described, but the present invention is not limited to this configuration, and the toner stirring mechanism 49 described above is provided at the central portion of the housing 43 as necessary. In addition, a rib or the like may be provided on the inner wall portion of the housing 43 to further promote the stirring of the toner.
[0043]
Furthermore, in the present embodiment, the case where the same number of stirring pieces constituting the stirring portion 492 is provided in the direction of the respective end portions 491a and 491b from the substantially central portion 491c of the support shaft portion 491 has been described. It is not limited to this configuration, and different numbers may be used as necessary. In the present embodiment, the case where the stirring pieces are arranged at substantially equal intervals from the substantially central portion 491c of the support shaft portion 491 in the direction of the end portions 491a and 491b has been described. It is not limited to a structure, You may provide each stirring piece with arbitrary space | intervals with respect to the support shaft part 491. FIG.
[0044]
In the present embodiment, the case has been described in which the angles formed by the surface normals Fa and Fb on the inclined upper surfaces of the stirring pieces 492a and 492b and the virtual lines Ha and Hb are acute angles θa and θb, respectively. The angles of the acute angles θa and θb are not limited to any value, and the acute angles θa and θb may be the same angle or different angles.
[0045]
Furthermore, the present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, the image forming apparatus according to the above embodiment is a printer that prints an image provided from an external device such as a host computer on a sheet such as copy paper, transfer paper, paper, and an OHP transparent sheet. The present invention can be applied to electrophotographic image forming apparatuses such as copying machines and facsimile machines.
[0046]
In the above-described embodiment, a color image is formed on the intermediate transfer belt 71 by performing a transfer process for transferring the toner image formed on the photoreceptor 21 onto the intermediate transfer belt 71 for each toner color. However, the present invention is also applied to an image forming apparatus that forms a color image by transferring a toner image to a transfer medium (transfer drum, transfer belt, transfer sheet, intermediate transfer drum, intermediate transfer sheet, etc.) other than the intermediate transfer belt. be able to.
[0047]
Furthermore, in the above embodiment, the present invention is applied to a developing device equipped in an image forming apparatus capable of forming a color image using four color toners. The image forming apparatus that forms a color image using toner of two colors, three colors, or five colors or more is not limited to the above, and the developing device is the so-called “rotary type” described in the above embodiment. If so, it can be applied naturally.
[0048]
Further, in the above embodiment, when the developing process is performed on the photosensitive member 2 by rotating the rotary developing unit 4 around the rotation shaft 4a, each of the developing devices 4Y, 4C, 4M, and 4K develops with the photosensitive member 2. It is fixed to the support frame 4b so that it can come into contact with the position DP in the order of the developing unit 4Y for yellow, the developing unit 4C for cyan, the developing unit 4M for magenta, and the developing unit 4K for black. The present invention is not limited to this configuration, and the developing devices 4Y, 4C, 4M, and 4K may be fixed to the support frame 4b in an arbitrary order. Therefore, for example, when developing processing is performed by rotating the rotary developing unit 4, the developing devices 4Y, 4C, 4M, and 4K are located at the developing position DP with respect to the photosensitive member 2 at the black developing device 4K and cyan. The developing unit 4C, the developing unit 4M for magenta, and the developing unit 4Y for yellow may be fixed to the support frame 4b so as to be contactable in this order.
[0049]
【The invention's effect】
As described above, in the developing device according to the present invention, the toner agitating mechanism that rotates relative to the housing that moves with the rotation of the developing device holding means is provided in the housing that contains the toner. Therefore, according to the present invention, the toner in the housing can be agitated without using the driving means, so that the toner can be prevented from being deteriorated, the number of parts can be reduced, the apparatus can be downsized, the cost can be reduced, and the like. Can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an image forming apparatus equipped with an embodiment of a developing device according to the present invention.
FIG. 2 is a partially enlarged view of the developing device of FIG.
FIG. 3 is a view for explaining a mounting state of a toner stirring mechanism in a developing device.
FIG. 4 is a schematic perspective view of a toner stirring mechanism.
FIG. 5 is a diagram for explaining an operating state of a toner stirring mechanism.
FIG. 6 is a schematic perspective view of a toner stirring mechanism according to another embodiment.
[Explanation of symbols]
2 ... Photoconductor (image carrier)
4 ... Rotary development unit
4Y, 4C, 4M, 4K ... Developer
4a ... Rotating shaft
4b ... Support frame (developer holding means)
43 ... Housing
44. Toner container
47. Developing roller (toner carrier)
49. Toner stirring mechanism (toner stirring means)
491 ... support shaft
491a ... One end
491b ... the other end
492 ... Stirrer
492a, 492c ... stirring pieces (first inclined stirring pieces)
492b, 492d ... stirring pieces (second inclined stirring pieces)
493 ... Balancer

Claims (4)

A plurality of developing units for developing the latent image formed on the image carrier with toner and a rotatable unit around a predetermined rotation axis, and holding the plurality of developing units arranged in the rotation direction. A developing device holding means, and by rotating and positioning the developing device holding means, one developing device of the plurality of developing devices is selectively arranged to face the image carrier, and a latent image by the developing device is provided. A developing device for developing toner,
Each developer is
A housing forming a toner containing portion for containing toner therein;
A toner carrier that conveys a portion of the toner contained in the toner container to a development position facing the image carrier;
Relative to the housing, which is disposed in the toner container in a state of being rotatably supported with respect to the housing, and moves concentrically around the rotation shaft as the developing device holding means rotates. A developing device comprising: a toner agitating means for agitating the toner in the toner accommodating portion by rotating. The toner agitating means is provided on the support shaft portion, a support shaft portion disposed substantially parallel to the rotation axis of the rotation shaft and having both ends pivotally supported with respect to the housing. And a balancer provided on at least one of the support shaft part and the stirring part,
The developing device according to claim 1, wherein a center of gravity of the balancer is positioned vertically below the axis of the support shaft to hold the stirring unit in a predetermined posture. The toner agitating means is provided on the support shaft portion, a support shaft portion disposed substantially parallel to the rotation axis of the rotation shaft and having both ends pivotally supported with respect to the housing. And a stirring part
The stirring unit has at least one stirring piece attached to the support shaft portion, and the center of gravity of the at least one stirring piece is positioned below the axis of the support shaft portion in the vertical direction. The developing device according to claim 1, wherein the stirring unit is held in a predetermined posture. The stirring portion includes at least one or more first inclined stirring pieces that are attached to the support shaft portion so as to be inclined from a substantially central portion of the support shaft portion to one end portion, and a substantially central portion of the support shaft portion. And at least one second inclined stirring piece attached to the support shaft portion inclined to the other end portion,
In a state where the stirring unit is held in the predetermined posture, the surface normal of the inclined upper surface of the first inclined stirring piece is a first virtual line extending from the attachment position of the inclined stirring piece toward the one end. The surface normal of the inclined upper surface of the second inclined stirring piece forms an acute angle with respect to the second imaginary line extending from the attachment position of the inclined stirring piece toward the other end. Or the developing device according to 3;

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