JP5104231B2 - Developing device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a rotary developing device and an improvement of an image forming apparatus using the same.

JP-A-10-142888 JP 2004-333684 A

  Conventionally, in an image forming apparatus using an electrophotographic method or an electrostatic recording method, a developing device that develops an electrostatic latent image formed on an image carrier such as a photosensitive drum is used. As such a developing device, a plurality of developing units are accommodated in a rotating frame, and corresponding developing units are opposed to the image holding body according to electrostatic latent images of different colors sequentially formed on the image holding body. There is known a so-called rotary type developing device that sequentially rotates and moves to a predetermined developing position to form a toner image of a predetermined color on the image carrier (see, for example, Patent Documents 1 and 2).

  Here, Patent Document 1 discloses a rotary type developing device configured to collect discharged developer at one place by utilizing the rotational movement of the developing unit.

  Further, in Patent Document 2, the developer surface near the discharge port can be stabilized in a short time by setting the cross-sectional area of the developer accommodating portion near the developer discharge port to be larger than the other regions. A rotary developing device is disclosed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device capable of suppressing the unexpected recovery of a developer accompanying a rotating operation in a rotary developing device and an image forming apparatus using the developing device at a low cost with a simple configuration. There is to do.

  In order to achieve the above object, the image forming apparatus according to claim 1 is arranged along the circumferential direction of the rotating body, and corresponds to images of different colors sequentially formed on the image holding body, A rotary developing device including a plurality of developing units that sequentially rotate and move to a predetermined developing position facing the image carrier, wherein the developing unit is rotatable to hold and convey a two-component developer to a developing area. And a first agitating and conveying member that agitates and conveys the two-component developer in the axial direction on the back side of the developing roll, and the two-component developer can be supplied to the developing roll. A first developer accommodating portion for accommodating, and a second agitating and conveying member that adjoins the first developer accommodating portion and conveys the two-component developer in a direction opposite to the first agitating and conveying member. The two-component developer can be circulated between the first developer container and the first developer container. And a developer discharge port having a shutter member that can be opened and closed by gravity. The second developer storage portion includes a second developer storage portion. At the same time, a developer discharge suppressing means for suppressing the opening operation of the shutter member by the movement of the developer accompanying the rotation of the rotating body is formed at a portion corresponding to the shutter member of the second stirring and conveying member. It is characterized by being.

  According to a second aspect of the present invention, there is provided the developing device according to the first aspect, wherein the developer discharge restraining means protrudes radially in the predetermined portion of the rotation shaft of the second agitating and conveying member in the axial direction. At least one flat plate member is attached to the rotating body in a state where the extending flat plate member is attached, the developing unit is moved to the developing position, and the driving of the second stirring and conveying member is stopped. The flat plate member is arranged so as to be positioned in the tangential direction of the rotation axis of the second stirring and conveying member when viewed from the center of rotation.

  According to a third aspect of the present invention, there is provided the developing device according to the second aspect, wherein the driving time of the developing unit is set to an integral multiple of the rotation period of the flat plate member / 2. It is.

  According to a fourth aspect of the present invention, there is provided the developing device according to the first aspect, wherein the developer discharge restraining means places a flat plate member in the circumferential direction on the predetermined portion of the rotation shaft of the second agitating and conveying member. It is characterized by being arranged at equal intervals at three or more locations.

  According to a fifth aspect of the present invention, in the developing device according to any one of the second to fourth aspects, an axial length of the flat plate member is longer than an axial length of the shutter member. It is what.

  An image forming apparatus according to a sixth aspect includes the developing device according to any one of the first to fifth aspects and an image forming unit that forms a predetermined image on a recording sheet.

  According to the first aspect of the present invention, the developer discharge suppressing means for suppressing the opening operation of the shutter member by the movement of the two-component developer accompanying the rotating operation of the rotating body does not add any new driving mechanism. Unexpected developer discharge due to rotational movement can be suppressed.

  According to the second aspect of the present invention, the opening operation suppressing means for suppressing the unexpected developer discharge due to the rotating operation of the rotating body can be easily realized with a simple configuration by arranging the flat plate member at a predetermined position. can do.

  According to the third aspect of the present invention, the phase of the flat plate member is necessarily the same phase or the reverse phase at the start of driving at the end of driving of the developing unit. The predetermined phase arrangement of the member can be ensured.

  According to the fourth aspect of the present invention, since at least one flat plate member is always disposed in a predetermined phase range, an unexpected development due to the rotating operation of the rotating body without any special drive mechanism or control is required. The developer discharge suppressing means for suppressing the discharge of the developer can be easily realized with a simple configuration.

  According to the fifth aspect of the present invention, the developer accumulated on the flat plate member is more effectively pressed against the shutter by utilizing the rotating operation of the rotating body, and the unexpected discharge of the developer accompanying the rotating operation is suppressed. can do.

  According to the sixth aspect of the present invention, the present invention can also be applied to an image forming apparatus including the developing device.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

  First, a schematic configuration of an embodiment of an image forming apparatus to which the present invention can be applied will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a color image forming apparatus 1 according to an embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a main body of a color image forming apparatus, and an automatic original conveying apparatus that automatically conveys originals 2 in a separated state one by one on the upper part of the main body 1 of the color image forming apparatus. 3 and a document reading device 4 for reading an image of the document 2 conveyed by the automatic document conveying device 3. The document reader 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reflects a reflected light image from the document 2 from a full-rate mirror 7, half-rate mirrors 8 and 9, and an imaging lens 10. The image reading element 11 composed of a CCD or the like is scanned and exposed through a reduction optical system, and the color material reflected light image of the document 2 is formed at a predetermined dot density (for example, 16 dots / mm) by the image reading element 11. It is supposed to read.

  The color material reflected light image of the document 2 read by the document reading device 4 is subjected to image processing, for example, as document reflectance data of three colors of red (R), green (G), and blue (B) (8 bits each). The image processing apparatus 12 sends a predetermined correction such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame erasing, color / moving editing, etc., to the reflectance data of the document 2. Image processing is performed.

  The image data that has been subjected to the predetermined image processing by the image processing apparatus 12 as described above is a four-color document of yellow (Y), magenta (M), cyan (C), and black (K) (each 8 bits). The color material gradation data is sent to a ROS 13 (Raster Output Scanner), and the ROS 13 performs image exposure with laser light in accordance with the original color material gradation data. The color image forming apparatus is also configured to function as a printer. When the color image forming apparatus functions as a printer, image data is input to the image processing apparatus 12 from a host computer such as a personal computer. After being input and subjected to predetermined image processing by the image processing apparatus 12, the original color material gradation data of four colors is output to the ROS 13.

  An image forming unit capable of forming a plurality of toner images having different colors is disposed inside the color image forming apparatus main body 1. The image forming means mainly includes a photosensitive drum 17 as an image carrier on which an electrostatic latent image is formed, and a plurality of toner images having different colors by developing the electrostatic latent image formed on the photosensitive drum 17. And a rotary type developing device 19 as developing means capable of forming the film.

  The ROS 13 modulates a semiconductor laser (not shown) according to the original color material gradation data, and emits a laser beam LB from the semiconductor laser according to the gradation data. The laser beam LB emitted from the semiconductor laser is deflected and scanned by the rotating polygon mirror 14 and scanned and exposed on the photosensitive drum 17 as an image carrier through the f · θ lens 15 and the reflecting mirror 16.

  The photosensitive drum 17 on which the laser beam LB is scanned and exposed by the ROS 13 is driven to rotate at a predetermined speed in the direction of the arrow by a driving unit (not shown). The surface of the photosensitive drum 17 is charged in advance with a predetermined polarity (for example, negative polarity) and potential by a scorotron 18 for primary charging, and then laser light LB is scanned and exposed in accordance with the original color material gradation data. As a result, an electrostatic latent image is formed. The electrostatic latent image formed on the photosensitive drum 17 can rotate four color developing units 19Y, 19M, 19C, and 19K of yellow (Y), magenta (M), cyan (C), and black (K). The rotary developing device 19 included in the image is reversely developed, for example, with a toner charged to a negative polarity that is the same as the charged polarity of the photosensitive drum 17 to form a toner image of a predetermined color. Specifically, for example, if the electrostatic latent image formed on the photosensitive drum 17 corresponds to yellow (Y), the electrostatic latent image is developed by the developing unit 19Y corresponding to yellow (Y). The toner image is developed and a yellow (Y) toner image is formed on the photosensitive drum 17. For other magenta (M), cyan (C), and black (K), corresponding color toner images are sequentially formed on the photosensitive drum 17 by the same process. The toner image formed on the photosensitive drum 17 is charged with negative polarity or the like by the pre-transfer charger 20 as necessary, and the charge amount is adjusted.

  The toner images of the respective colors formed on the photosensitive drum 17 are transferred in multiple by a primary transfer roll 22 onto an intermediate transfer belt 21 as an intermediate transfer member disposed below the photosensitive drum 17. The intermediate transfer belt 21 includes a driving roll 23, a driven roll 24 a, a driven roll 24 b, a tension roll 24 c, a driven roll 24 d, and a backup roll 25 as a counter roll that constitutes a part of the secondary transfer unit. It is supported so as to be rotatable along the direction of the arrow at the same moving speed as the peripheral speed.

  On the intermediate transfer belt 21, all four colors of yellow (Y), magenta (M), cyan (C), and black (K) formed on the photosensitive drum 17 in accordance with the color of the image to be formed. Alternatively, a part of the toner image is transferred in a state of being sequentially superimposed by the primary transfer roll 22. Specifically, when a single color image is formed, a toner image of a predetermined color that is primarily transferred onto the intermediate transfer belt 21 is immediately secondary transferred onto the recording paper 26, but a toner image of a plurality of colors is used. In the case of forming a color image in which the toner images are superimposed, the steps of forming a toner image of a predetermined color on the photosensitive drum 17 and performing primary transfer of the toner image onto the intermediate transfer belt 21 are performed for a predetermined number of colors. Only repeated.

  For example, when a full color image is formed by superimposing four color toner images of yellow (Y), magenta (M), cyan (C), and black (K), each rotation of the toner image is formed on the photosensitive drum 17. In addition, yellow (Y), magenta (M), cyan (C), and black (K) toner images are sequentially formed, and these four color toner images are sequentially superimposed on the intermediate transfer belt 21. The primary transfer.

  At this time, the intermediate transfer belt 21 is rotated at a period synchronized with the photosensitive drum 17 while holding the yellow (Y) unfixed toner image that was first primarily transferred, and on the intermediate transfer belt 21. The magenta (M), cyan (C), and black (K) unfixed toner images are transferred in such a manner that they are sequentially superimposed on the yellow (Y) unfixed toner images for each rotation.

  The unfixed toner image primarily transferred to the intermediate transfer belt 21 in this way is conveyed to a secondary transfer position facing the conveyance path of the recording paper 26 as the intermediate transfer belt 21 rotates. The toner image transferred onto the intermediate transfer belt 21 is placed on a recording sheet 26 as a transfer member that is conveyed to a secondary transfer position at a predetermined timing, and a backup roll 25 that supports the intermediate transfer belt 21, Transfer is performed by the pressure contact force and electrostatic force of the secondary transfer roll 27 that constitutes a part of the secondary transfer unit that is in pressure contact with the backup roll 25.

  On the other hand, as shown in FIG. 1, the recording paper 26 is supplied from any one of a plurality of paper feeding cassettes 28, 29, 30, and 31 serving as recording paper accommodation members disposed in the lower part of the color image forming apparatus main body 1. Paper of a predetermined size is fed by feed rolls 28a, 29a, 30a, 31a. The fed recording paper 26 is conveyed to a secondary transfer position of the intermediate transfer belt 21 by a plurality of conveying rolls 32 and registration rolls 33 at a predetermined timing. Then, as described above, a toner image of a predetermined color is collectively transferred from the intermediate transfer belt 21 to the recording paper 26 by the backup roll 25 and the secondary transfer roll 27 as secondary transfer means. It has become so.

  The recording paper 26 onto which the toner image of a predetermined color has been transferred from the intermediate transfer belt 21 is separated from the intermediate transfer belt 21 and then conveyed to the fixing device 35 by the conveying belt 34. Thus, the toner image is fixed on the recording paper 26 by heat and pressure, and in the case of single-sided copying, the toner image is directly discharged onto the paper discharge tray 36 and the color image copying process is completed.

  In the case of duplex copying, the recording paper 26 on which the color image is formed on the first surface (front surface) is not discharged onto the paper discharge tray 36 as it is, but the conveyance direction is changed downward by a reversing gate (not shown). The three rolls are temporarily conveyed to the reverse passage 39 by the tri-roll 37 and the reverse roll 38 in pressure contact. Then, the recording paper 26 is conveyed to the double-sided passage 40 by the reversing roll 38 which is reversed this time, and is temporarily conveyed to the registration roll 33 by the conveying roll 41 provided in the double-sided passage 40 and stopped. The recording paper 26 is transported again by the registration roll 33 in synchronization with the toner image on the intermediate transfer belt 21, and the toner image transfer / fixing process is performed on the second surface (back surface) of the recording paper 26. After being performed, it is discharged onto the discharge tray 36. In the figure, reference numeral 42 denotes a cleaning device for removing residual toner, paper dust and the like from the surface of the photosensitive drum 17 after the transfer process is completed, and reference numeral 43 denotes a manual feed tray.

  Next, the configuration of the rotary developing device according to the present embodiment will be described with reference to FIG. Here, FIG. 2 is a schematic diagram showing a configuration of the rotary developing device according to the present embodiment.

  As schematically shown in FIG. 2, the rotary developing device 19 according to this embodiment includes four developing units 19Y of yellow (Y), magenta (M), cyan (C), and black (K). , 19M, 19C, 19K are mounted at predetermined intervals along the circumferential direction of the rotating frame 19F that rotates about the rotating shaft 19o. The four developing units 19Y, 19M, 19C, and 19K of yellow (Y), magenta (M), cyan (C), and black (K) are provided with the rotation position of the rotation frame 19F in the rotation frame 19F. The developing rolls 190Y, 190M, 190C, and 190K provided in the opening portions of the developing units 19Y, 19M, 19C, and 19K are opposed to the photosensitive drum 17 by detecting and controlling the positions based on the positions of the slits (not shown). The electrostatic latent image of each color is developed with the corresponding toner of each color by sequentially moving to a predetermined development position and applying a predetermined development electric field. In the present embodiment, the rotating shaft 19o is formed in a hollow cylindrical shape, and a waste developer discharge channel discharged from a developer discharge port of each of the developing units 19Y, 19M, 19C, and 19K described later. Is also used.

  Further, the yellow (Y), magenta (M), cyan (C), and black (K) developing units 19Y, 19M, 19C, and 19K are adjacent to the developing units 19Y, 19M, 19C, and 19K. As described above, the toner cartridges TY, TM, TC, and TK are mounted. For example, when the toner density in the developing units 19Y, 19M, 19C, and 19K falls below a predetermined density range due to a developing action or the like based on the detection result of a density sensor (not shown), the toner cartridges TY and TM , TC, TK to supply the corresponding color toner to each developing unit 19Y, 19M, 19C, 19K, thereby maintaining the toner density in each developing unit 19Y, 19M, 19C, 19K within a predetermined range. Is possible. Note that a two-component developer composed of toner and a magnetic carrier is used as the developer in the present embodiment.

  In this embodiment, among the four toner cartridges TY, TM, TC, and TK of yellow (Y), magenta (M), cyan (C), and black (K), the black that consumes the largest amount of toner. The (K) toner cartridge TK is formed larger than the other color toner cartridges TY, TM, and TC, and the black (K) toner cartridge TK contains a large amount of toner. It is configured to be able to.

  Next, details of each developing unit constituting the rotary type developing apparatus according to the present embodiment will be described with reference to FIGS. Here, FIG. 3 is a schematic cross-sectional view for explaining the configuration of the developing unit according to the present embodiment, and FIG. 4 is a diagram for explaining the flow path configuration of the developing unit according to the present embodiment. It is a typical top view. Since the developing units 19Y, 19M, 19C, and 19K and their constituent members have the same structure, the symbols are hereinafter collectively referred to (for example, the developing unit 19).

  As shown in FIG. 3, the developing unit 19 according to the present embodiment is a developing unit that accommodates a two-component developer by opening a corresponding part in a predetermined developing region facing the photosensitive drum 17 that is an image carrier. A developing roll 190 that is a developer holding member is disposed facing the opening of the developing housing 191, and a two-component developer is placed in a portion of the developing housing 191 adjacent to the developing roll 190. The first developer accommodating portion 193a to be accommodated is adjacent to the first developer accommodating portion 193a via the partition wall W and communicates with the first developer accommodating portion 193a at both axial end portions thereof. And a second developer container 193b. Each of the first developer accommodating portion 193a and the second developer accommodating portion 193b according to the present embodiment has a space for accommodating the two-component developer, and the first developer accommodating portion 193a. A spiral supply auger 195 that is a first agitating and conveying member that conveys the two-component developer in a predetermined axial direction (for example, from the back side to the near side in FIG. 3) is disposed. On the other hand, in the second developer accommodating portion 193b, a spiral that is a second agitating and conveying member that conveys the two-component developer in a direction opposite to the supply auger 195 (for example, from the front side to the back side in FIG. 3). A shaped admix auger 197 is provided.

  In the present embodiment, the developing roll 190 includes a developing sleeve 190a that rotates in a predetermined direction (for example, clockwise direction) during a developing operation, and a magnet roll 190b fixed inside the developing sleeve 190a. Yes.

  Here, the developing sleeve 190a rotates in a predetermined direction, and faces the photosensitive drum 17 at a predetermined separation distance at the opening of the developing housing 191 in a predetermined developing area facing the photosensitive drum 17. Settings are arranged. The developing sleeve 190a is connected to a bias power source (not shown) for applying a developing bias composed of a DC bias with an alternating current superimposed thereon.

  The magnet roll 190b is formed by arranging a plurality of magnet members in the circumferential direction to form a roll, and includes a developing magnetic pole arranged corresponding to the developing region and a conveying magnetic pole arranged at a predetermined angular interval. A pick-off magnetic pole, a trimming magnetic pole, a pick-up magnetic pole, and the like. The arrangement and number of magnetic poles in the magnet roll 190b may be appropriately selected.

  Further, in the vicinity of the lower side of the developing roll 190, a substantially L-shaped layer thickness regulating member 194 extending along the axial direction of the developing roll 190 so that the facing surface thereof is close to the developing roll 190 with a predetermined gap. The two-component developer on the developing roll 190 is regulated to a predetermined amount (layer thickness).

  As shown in FIG. 4, in the present embodiment, the supply auger 195 accommodated in the first developer accommodating portion 193a supplies the two-component developer in a predetermined axial direction (from right to left in FIG. 4). And has a spiral blade 195b formed around the rotation shaft 195a. The spiral blade 195b is disposed in the first developer container 193a so as to be close to the surrounding wall surface. (See FIG. 3).

  On the other hand, the admix auger 197 accommodated in the second developer accommodating portion 193b has a rotating shaft so that the two-component developer is agitated and conveyed in the direction opposite to the supply auger 195 (from left to right in FIG. 4). A spiral blade 197b formed around 197a is provided, and this spiral blade 197b is disposed in the second developer container 193b so as to be close to the surrounding wall surface (see FIG. 3). ). The supply auger 195 accommodated in the first developer accommodating portion 193a and the admix auger 197 accommodated in the second developer accommodating portion 193b are partitioned by the partition wall W and partitioned. By opening both ends in the axial direction (longitudinal direction) of the wall, the first developer accommodating portion 193a and the second developer accommodating portion 193b are communicated with each other. In FIG. 4, a developer circulation conveyance path that circulates and conveys in the counterclockwise direction indicated by the arrow is formed.

  In the developing unit 19 according to the present embodiment configured as described above, the two-component developer in the developing housing 191 is transported by a pair of developer agitators at a predetermined developing position where the developing roll 190 faces the photosensitive drum 17. The material is stirred while being circulated and conveyed by members 195 and 197, and is captured by the pickup magnetic pole in the developing roll 190. Thereafter, the captured two-component developer is conveyed in the rotating direction of the developing roll 190 (developing sleeve 190a) by the magnetic attraction force of the pickup magnetic pole and the frictional force between the surface of the developing roll 190. When the conveyed two-component developer reaches the vicinity of the layer thickness regulating member 194, it forms spikes by the trimming magnetic pole. Further, the spikes of the two-component developer are regulated by the layer thickness regulating member 194, so that a developer layer having a predetermined layer thickness is formed on the developing roll 190 and conveyed to the development area. Further, the developer layer of the two-component developer conveyed to the development area forms a magnetic brush by the magnetic attraction force of the developing magnetic pole, and the toner in the two-component developer that forms this magnetic brush is the same as the photosensitive drum 17. The electrostatic latent image on the photosensitive drum 17 is visualized by a developing electric field formed between the developing roll 190. On the other hand, the surplus toner that has passed through the developing area moves along with the rotation of the developing roll 190 and is returned to the developing housing 191 again by the magnetic force of the pick-off magnetic pole to prepare for the next developing operation.

  Here, the rotating members of the developing roll 190, the supply auger 195, and the admix auger 197 are rotationally driven when the developing unit 19 moves to a predetermined developing position facing the photosensitive drum 17 and performs the developing operation. These rotating members are stopped during the rotating operation of the rotating frame 19F (hereinafter also referred to as a revolving operation). In other words, the rotating members of the developing roll 190, the supply auger 195, and the admix auger 197 are driven to rotate only during a predetermined developing period during which the developing operation is performed after the developing unit 19 has moved to a predetermined developing position. It is like that.

  Further, as best shown in FIG. 4, in the developing unit 19 according to the present embodiment, the extended region end of the partition wall W (the upstream end along the developer transport direction of the admix auger 197). ) Is formed on the side wall of the second developer accommodating portion 193b corresponding to (2), a developer collecting portion 200 having a substantially U-shaped cross section protruding from the side wall, so that the deteriorated developer is gradually discharged. The trickle method is adopted.

  Specifically, as best shown in FIG. 3, it is on the developer collection unit 200 side of the admix auger 197 and is substantially above the rotation axis center 197a (in FIG. 3, the rotation axis center of the admix auger 197). A developer discharge port 205 having a plate-like shutter member 205S is opened on the upper right of 197a. The shutter member 205S has a rotation shaft 205Sa in the vicinity of the upper end side of the developer discharge port 205, and is attached so that it can be opened and closed by gravity as the rotating frame 19F rotates. The operation enables communication / shielding between the second developer accommodating portion 193b and the developer collecting portion 200. As a result, the shutter member 205S is opened and closed without any drive mechanism in accordance with the revolving operation of the rotating frame 19F, and the deteriorated developer is introduced into the developer recovery unit 200 and discharged. .

  In the developing device configured to collect the deteriorated developer by opening and closing the shutter member 205S using the revolution operation of the rotating frame 19F in this way, a special drive mechanism for collecting the developer is provided. The shutter member 205S is easy to be opened due to vibration during the revolution operation, and the operation becomes unstable due to the need to reduce the size and cost. The problem of becoming will arise.

  Therefore, in the present embodiment, by providing the following developer discharge suppression means, the opening operation of the shutter member 205S during the revolution operation is stabilized without providing any special drive mechanism, Unexpected developer discharge is prevented. Hereinafter, the configuration of the developer discharge suppressing unit according to the present embodiment will be further described with reference to the drawings.

  As shown in FIG. 3, the developer discharge suppressing unit according to the present embodiment rotates the flat plate member 210 protruding in the radial direction along the axial direction at a portion corresponding to the shutter member 205 </ b> S of the admix auger 197. The flat plate member 210 is attached to the shaft 197a and arranged in a predetermined phase (position). Specifically, as shown schematically in FIG. 5, the flat plate member 210 is in a state in which an arbitrary developing unit 19 has moved to a predetermined developing position and the rotation of the admix auger 197 has stopped. The tangential direction of the center of the rotation axis 197a of the admix auger 197 viewed from the center of the rotation axis 19o of the rotation frame 19F (the straight line connecting the center of the rotation axis 19o of the rotation frame 19F and the center of the rotation axis 197a of the admix auger 197) It is arranged so that at least one flat plate member 210 exists in the direction of a straight line Lo that is orthogonal and passes through the center of the rotation shaft 197a. FIG. 5 shows an example in which the flat plate member 210 is disposed on the tangent Lo and above the rotation shaft 197a. However, the flat plate is disposed below the rotation shaft 197a (phase position reversed with the flat plate member 210). A flat member (a flat plate member 210 ′ indicated by a dotted line in the figure) may be provided, or two flat plate members 210 and 210 ′ may be provided in both the upper and lower directions of the rotating shaft 197a.

  6 and 7 are compared with the case where the flat plate member 210 is arranged at such a predetermined phase (position) in comparison with the case where the flat plate member 210 is arranged at a position other than the predetermined phase (position). The description will be given with reference. Here, FIG. 6 is a diagram for explaining the operation when the flat plate member 210 is arranged at a position other than the predetermined phase (position), and FIG. 7 is the case when the flat plate member 210 is arranged at the predetermined phase (position). It is a figure explaining an effect | action.

  First, as shown in FIG. 6A, in the state where the developing unit 19 has moved to a predetermined developing position and the rotation of the admix auger 197 has stopped (hereinafter, this state is also referred to as a reference position), the flat plate When the shaped member 210 exists outside a predetermined phase (in this example, 3 o'clock direction as viewed from the rotation axis center 197a), the developer interface is formed between the first developer accommodating portion 193a and the second developer. The shutter member 205 </ b> S is opened by gravity to open the developer discharge port 205 over the housing portion 193 b.

  Next, when the rotating frame 19F rotates approximately 90 ° in a predetermined direction (clockwise direction in this example) in accordance with the revolution operation, the second developer accommodating portion 193b develops when the state shown in FIG. The shutter member 205S is closed by gravity and closes the developer discharge port 205 while being filled with the developer. At this time, the flat plate member 210 is moved in the direction of about 6 o'clock when viewed from the rotation axis center 197a with the revolution operation.

Further, when the rotating frame 19F rotates approximately 90 ° to the state shown in FIG. 6 (3), the shutter member 205S maintains the state where the developer discharge port 205 is closed, but the flat plate member 210 performs the revolution operation. Along with this rotation, the developer G ₀ is accumulated (residual) around the flat plate member 210 in the upper and lower portions.

Thereafter, when the rotating frame 19F further rotates by approximately 90 ° to reach the state of FIG. 6 (4), the developer G ₀ deposited around the flat plate member 210 in the state of FIG. While moving with the rotational movement of 210, it falls to the first developer accommodating portion 193a and the developing roll 190 side due to the influence of gravity. At this time, the shutter member 205S is also opened by gravity to open the developer discharge port 205. However, the shutter member 205S is dropped due to vibrations caused by the rotational movement when moving from FIG. 6 (3) to FIG. 6 (4). The developer G ₀ to be moved up is lifted up by the flat plate member 210, and the developer G ₀ rides on the shutter member 205S and is discharged as an unexpected and unexpected developer. That is, when the opening / closing operation of the developer discharge port 205 is performed using the revolving operation without providing any driving mechanism as in the developing device according to the present embodiment, the revolving operation as described above is performed. At this time, unexpected developer is discharged with the unstable operation of the shutter member 205S, resulting in instability of the developer recovery amount. In particular, this tendency becomes a significant problem with the recent increase in the operation speed of developing devices.

  In addition, even when the flat plate member 210 is arranged at the position (9 o'clock direction as viewed from the rotation axis center 197a) and the position (9 o'clock direction as viewed from the rotation axis center 197a) in the above example (revolution axis center 197a), the revolution is caused by the same action. Unexpected developer discharge occurs during operation.

  Therefore, in order to avoid such a problem, an operation in the case where the flat plate member 210 is arranged in the substantially tangential line Lo direction of the rotation shaft 197a of the admix auger 197 at the reference position will be described with reference to FIG.

  As shown in FIG. 7A, when the developing unit 19 is at the reference position, the flat plate member 210 is substantially in the tangential Lo direction (in this example, 12 o'clock direction when viewed from the rotation axis center 197a). The developer interface is substantially horizontal across the first developer accommodating portion 193a and the second developer accommodating portion 193b, and the shutter member 205S is opened by gravity to open the developer discharge port 205. It is open.

  Next, when the rotating frame 19F is rotated by approximately 90 ° in a predetermined direction (clockwise direction in this example) in accordance with the revolution operation and becomes the state of FIG. 7B, the second developer accommodating portion 193b develops. The shutter member 205S is closed by gravity and closes the developer discharge port 205 while being filled with the developer. At this time, the flat plate member 210 is moved in the 3 o'clock direction as viewed from the rotation axis center 197a along with the revolution operation.

Further, when the rotating frame 19F rotates approximately 90 ° to the state shown in FIG. 7 (3), the shutter member 205S maintains the state where the developer discharge port 205 is closed, but the flat plate member 210 performs the revolution operation. Along with this rotation, the developer G ₁ is accumulated (residual) on the left side of the flat plate member 210.

Thereafter, when the rotating frame 19F further rotates by approximately 90 ° to reach the state shown in FIG. 7 (4), the developer G ₁ on the left side of the flat member 210 in the state shown in FIG. As the plate member 210 moves while pressing the shutter member 205S against the developer discharge port 205 side, the developer G ₁ deposited on the upper side (downstream in the rotation direction) is prevented from dropping due to gravity. Further, the unstable opening operation of the shutter member 205S can be suppressed, and thereby, the unexpected developer discharge accompanying the revolution operation can be suppressed.

  In addition, even when the flat plate member 210 is arranged at a position (6 o'clock direction as viewed from the rotation axis center 197a) in the above example (12 o'clock direction as viewed from the rotation axis center 197a) and a reversal phase (rear rotation axis center 197a as viewed from the 6 o'clock direction). Unexpected developer discharge due to movement can be suppressed.

  In the above example, the rotation axis center 19o of the rotating frame 19F and the admix auger at the reference position (the developing unit 19 has moved to the predetermined developing position and the admix auger 197 has stopped rotating). Although the rotation axis center 197a of 197 is in a horizontal state, even when the state where both are not horizontal is the reference position, the arrangement of the plate-like members 210 is set in the substantially tangential Lo direction at the reference position. Therefore, the discharge of the developer can be effectively suppressed. Further, in this example, at the reference position, the rotation axis center 19o of the rotation frame 19F, the rotation axis center 197a of the admix auger 197, and the rotation axis center 195a of the supply auger 195 are all in a horizontal state. For example, in the developing unit having a configuration in which the rotation axis center 195a of the supply auger 195 and the rotation axis center 197a of the admix auger 197 are different in height, the arrangement of the flat plate members 210 is substantially tangential at the reference position. By setting the Lo direction, the developer discharge can be effectively suppressed.

  Next, as described above, the developer discharge when the arrangement of the flat plate member 210 is changed (in this example, 3 o'clock direction, 6 o'clock direction, 9 o'clock direction, 12 o'clock direction as viewed from the rotation axis center 197a). The verification results obtained by measuring the amount are shown in FIG. In the figure, level 1 indicates the mounting position of the flat plate member 210 at 3 o'clock, level 2 at 9 o'clock, level 3 at 12 o'clock, and level 4 at 6 o'clock. Further, as a criterion for judgment, if the amount is 10 g or less at 500 revolutions of revolution, the developer recovery amount is appropriate, and if it exceeds that, it is judged that the unexpected developer accompanying the revolutions is collected. The

  As can be seen from FIG. 8, the level 1 to level 4 have good linearity, and in the case of level 1 (3 o'clock direction), the development is about 16.5 g at the revolution operation of 500 revolutions. In the case of level 2 (9 o'clock direction), the amount of the agent recovered was about 13.3 g at the time of the revolution operation of 500 revolutions. Therefore, in the case of level 1 (in the 3 o'clock direction) and level 2 (in the 9 o'clock direction), it is determined that any unexpected developer accompanying the revolution operation is discharged.

  On the other hand, in the case of level 3 (12 o'clock direction), the developer recovery amount is about 7.3 g at 500 revolutions, and in level 4 (6 o'clock), at 500 revolutions. It was found that the developer recovery amount was about 5.8 g, all satisfying the standard value of 10 g or less, and unexpected developer discharge accompanying the revolution operation was suppressed.

  That is, it is understood that, by arranging the flat plate member 210 in the substantially tangent Lo direction of the admix auger 197 at the reference position, unexpected developer discharge associated with the revolution operation can be suppressed.

  In order to control the flat plate member 210 to be arranged in the substantially tangential Lo direction at the reference position, for example, the position of the drive gear (not shown) of the admix auger 197 is detected by an optical sensor or the like. The phase position 210 may be controlled, but the driving (operation) time of the developing unit 19 may be set to be an integral multiple of the rotation period / 2 of the admix auger 197.

  In such a configuration, once the arrangement of the flat plate member 210 is set at the reference position, the position of the flat plate member 210 is the same phase as the initial state or the reverse phase when the development unit 19 is driven. Therefore, the flat plate member 210 always exists at the predetermined position, and the discharge of the developer due to the revolution operation can be effectively suppressed.

  Furthermore, in order to suppress the discharge of the developer accompanying the revolution operation, it is preferable to arrange at least one flat plate member 210 in the substantially tangential Lo direction at the reference position as described above. As schematically shown in FIG. 9, at least one flat plate member 210 is provided in any one of the upper and lower regions (shaded region in the drawing) viewed from the rotation axis 197a of ± 45 ° with respect to the tangent line Lo. If it exists, it has been found that the reference value (in this example, the developer recovery amount is 10 g or less at 500 revolutions) and a certain degree of suppression effect can be obtained.

  Therefore, as a simpler configuration of the developer discharge suppressing means, as shown in FIG. 9, three or more flat plate members are provided on the rotary shaft 197a at a portion corresponding to the shutter member 205S of the admix auger 197. You may comprise so that it may arrange | position with the space | interval at equal intervals in the circumferential direction (In this example, 3 plate-shaped member 210a, 210b, 210c is arrange | positioned in the circumferential direction at intervals of 120 degrees seeing from the rotation center 197a).

  In the case of such a configuration, at least one flat plate member 210 is necessarily arranged in the predetermined area (the hatched area in the figure), so that no special drive mechanism is required, And it becomes possible to suppress the unexpected discharge | emission of the developer accompanying a revolution operation with a simple structure, without requiring any special control.

  The developer discharge suppressing means according to the present invention is not limited to the flat plate member described above, and a member capable of suppressing the shutter opening operation using the movement of the developer accompanying the revolution operation is added. It can be configured by being provided at a predetermined part of the rotating shaft of the mix auger.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. 1 is a schematic cross-sectional view illustrating a configuration of an embodiment of a developing device according to the present invention. FIG. 2 is a schematic cross-sectional view illustrating a configuration of an embodiment of a developing unit according to the present invention. It is a schematic diagram which shows the structure of one Embodiment of the developer stirring conveyance member which concerns on this invention. It is a schematic diagram for demonstrating arrangement | positioning of the flat member which concerns on this invention. It is a schematic diagram for demonstrating an effect | action at the time of arrange | positioning the flat member which concerns on this invention out of a predetermined | prescribed phase (position). It is a schematic diagram for demonstrating an effect | action at the time of arrange | positioning the flat member which concerns on this invention in a predetermined phase (position). It is a figure which shows the verification result which measured the developer collection | recovery amount at the time of changing the attachment position of a flat member. It is a schematic diagram for demonstrating the structure which has arrange | positioned the several flat member at the circumferential direction at equal intervals.

Explanation of symbols

  1: color image forming device, 17: photosensitive drum, 18: scorotron, 19: developing device, 19F: rotating frame, 19Y, 19M, 19C, 19K: developing unit, 19o: rotating shaft, 21: intermediate transfer belt, 22: Primary transfer roll, 25: backup roll, 26: recording paper, 27: secondary transfer roll, 28: paper feed cassette, 33: registration roll, 34: transport belt, 35: fixing device, 190: development roll, 190a: development Sleeve, 190b: magnet roll, 191: developing housing, 193a: first developer accommodating portion, 193b: second developer accommodating portion, 194: layer thickness regulating member, 195: supply auger, 197: admix auger, 197a: Rotating shaft, 197b: Blade, 200: Developer recovery unit, 200S: Shutter member, 205: Current Agent outlet, 205S: shutter member, 205Sa: rotary shaft, 210,210a, 210b, 210c: plate member, TY, TM, TC, TK: toner cartridge, Lo: tangential, W: partition wall

Claims (5)

A plurality of developments arranged along the circumferential direction of the rotating body and sequentially rotating and moving to predetermined developing positions facing the image holding body corresponding to the images of different colors sequentially formed on the image holding body. A rotary type developing device equipped with a unit,
The developing unit includes a developing roller that is rotatably formed to hold and convey the two-component developer to the developing area;
A first developer container having a first agitating and conveying member that agitates and conveys the two-component developer in the axial direction on the back side of the developing roll, and accommodates the two-component developer so as to be supplied to the developing roll. And
A second agitating and conveying member that adjoins the first developer accommodating section and conveys the two-component developer in a direction opposite to the first agitating and conveying member; A second developer container that is circulated between the developer container and the developer container,
A developer discharge port having a shutter member that can be opened and closed by gravity is formed at one axial end portion of the second developer accommodating portion, and the shutter member of the second agitating and conveying member. in the portions corresponding, and suppressing developer discharge suppression means the opening operation of the gravitational direction before Symbol shutter member is formed,
The developer discharge restraining means allows the developer moving with the rotation of the rotating body to be located above the developer discharge restraining means and in the state where the shutter member is in a position where the shutter member can be opened in the direction of gravity. A developing apparatus characterized in that the opening operation in the direction of gravity of the shutter member is suppressed by depositing downward . The developer discharge suppressing means attaches a flat plate-like member that protrudes in the radial direction and extends in the axial direction to the predetermined portion of the rotation shaft of the second agitating and conveying member, and the developing unit moves to the developing position. And, in a state where the driving of the second agitating and conveying member is stopped, at least one of the flat plate members is on a surface passing through the rotation center of the rotating body and the rotation axis center of the second agitating and conveying member. 2. The developing device according to claim 1, wherein the flat plate member is disposed so as to protrude in a direction perpendicular to the developing device.   The developer discharge suppressing means is configured by arranging flat members at three or more locations in the circumferential direction at equal intervals on the predetermined portion of the rotation shaft of the second stirring and conveying member. The developing device according to claim 1. The axial length of the flat plate-like member, a developing device according to claim 2 or 3, characterized in that longer than the axial length of the shutter member. A developing device according to any one of claims 1 to 4, the image forming apparatus, comprising an image forming means for forming a predetermined image on the recording sheet.

Images