JP2016031497A - Toner supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner supply device to a developing device 4, which can be used for a long period of time in any environment without causing toner clogging at a toner discharge port.SOLUTION: A toner supply device comprises: a storage part 301 which stores toner supplied from a toner container 70; conveyance means 303 of conveying the toner stored in the storage part 301 toward a developing device 4; detection means 53, 54 of detecting a toner amount level of the toner stored in the storage part 301; and control means 50 of carrying out toner supply from the toner container 70 to the storage part 301 until the toner amount level recovers to a predetermined level after toner is supplied by a predetermined amount to the developing device 4 by placing the conveyance means 303 in operation by a predetermined amount after detecting that the toner amount level is less than the predetermined level by the detection means 53, 54.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a toner replenishing device that supplies toner, which is taken out from a toner container and stored in a storage unit, to a developing device.

  Here, the toner is colored particles (powder) that adhere to the latent image formed on the image carrier and develop (develop) the latent image. Includes transparent and white ones. The two-component developer is a mixture of the toner (nonmagnetic or magnetic) and the carrier (magnetic or nonmagnetic), and the one-component developer is a toner (magnetic or nonmagnetic) only.

  In an image forming apparatus that forms a toner image and forms an image, a developing apparatus that uses a two-component developer also uses a one-component developer to supplement the toner in the developing apparatus consumed by the image formation. Is also equipped with a toner replenishing device.

  The toner replenishing device stores a certain amount of toner taken out from the toner container in a storage unit (hopper: storage unit), operates the conveying means at a necessary timing, and supplies the toner from the storage unit to the developing device. Yes.

  Patent Document 1 discloses toner replenishment in which toner taken out from a toner bottle, which is an example of a toner container, is stored in a small-capacity hopper, and the toner taken out from the bottom of the hopper is pumped and replenished to a developing device at a high place by a screw conveyance mechanism. The device is shown.

  The toner replenishing device needs to replenish a proper amount of toner from a toner container at a proper timing and continue to store a substantially constant amount of toner in the storage unit. Even if the storage amount (toner amount level) of toner in the storage portion becomes excessive or small, the amount of toner supplied to the developing device by the conveying means becomes large, which adversely affects the quality of the output image. Because.

  Accordingly, it has been proposed to form a light path that is shielded by the toner stored in the storage portion by arranging a pair of light transmitting members on the side wall of the storage portion. It has been proposed to control the removal of toner from the toner container by evaluating the toner amount level in the reservoir by transmitting / blocking light transmitted through the light transmitting member.

  In addition, in a toner replenishing device that stores a plurality of conveying members that convey toner from one end side to the other end side in the longitudinal direction of the storage unit, even if a discharge port that discharges toner from the side surface of the storage unit is provided, the discharge port is stable. Therefore, the toner can be conveyed. For this reason, in Patent Document 1, when a plurality of conveying members are arranged in a storage portion provided with a discharge port on the side surface, the toner flow from the plurality of transfer members to the discharge port is stabilized, and the amount of toner taken out from the discharge port The variation of the is to be less.

JP 2010-256758 A

  In the configuration disclosed in Patent Document 1, the flow of toner from a plurality of conveying members to the discharge port is stable, and the variation in the amount of toner taken out from the discharge port can be reduced. However, it has been found that toner clogging may occur at the discharge port under conditions where the toner adhesion is large, such as in a high temperature and high humidity environment. After the toner having a large adhesion force is transported by the upper transport unit, toner adhesion on the wall surface gradually grows in the transport path from the discharge port to the developing device, and the toner closes the discharge port, resulting in toner clogging. It has been found.

  The present invention is a further development of the above prior art. An object of the present invention is to provide a toner replenishing device that can be used for a long period of time so as not to cause toner clogging at a toner discharge port without being influenced by the environment.

  A typical configuration of a toner replenishing device according to the present invention for achieving the above object is a toner replenishing device for a developing device, in which a storage unit for storing toner supplied from a toner container, and the storage unit Conveying means for conveying the stored toner toward the developing device, detecting means for detecting the toner amount level of the toner stored in the storing portion, and the detecting means being less than a predetermined level with respect to the toner amount level The toner is supplied from the toner container to the storage unit until the toner amount level is restored to a predetermined level after the conveying means is operated for a predetermined amount to supply a predetermined amount of toner to the developing device. And a control means.

  According to the present invention, it is possible to provide a toner replenishing device that can be used for a long period of time even if the toner has a large adhesive force, without being influenced by the environment and without causing clogging at the toner discharge port. it can.

1 is an explanatory diagram of a configuration of an example of an image forming apparatus. FIG. 4 is a schematic diagram for explaining a developing device, a toner replenishing device for the developing device, and a control system. FIG. 3 is a partially cutaway perspective view of the toner supply device. It is sectional drawing similarly seen from the side surface. It is sectional drawing similarly seen from the rear side. It is a control flowchart. It is a block diagram of a control system. In Example 1, the amount of toner replenished after screw rotation and the durable number of occurrences of toner clogging In Example 2, the amount of toner replenished after screw rotation and the durable number of occurrences of toner clogging

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. According to the present invention, after the detection unit detects that the toner amount level in the toner storage unit is less than a predetermined level, the transport unit is operated by a predetermined amount to supply a predetermined amount of toner to the developing device, and then the toner container is moved from the toner container to the storage unit. As long as toner supply is executed, the configuration can be changed freely. That is, another embodiment in which part or all of the configuration of the embodiment is replaced with the alternative configuration can be implemented.

  Therefore, the present invention is not limited to the toner replenishing device and the developing device of the developing device using the two-component developer, but can be implemented by the developer (toner) replenishing device and the developing device of the developing device using the one-component developer. In this embodiment, only main parts related to toner image formation / transfer will be described. However, the present invention adds printers, various printing machines, copying machines, FAX machines, in addition to necessary equipment, equipment, and housing structure. It can be implemented in various applications such as a multifunction machine.

[Example 1]
<Image forming apparatus>
FIG. 1 is an explanatory diagram of a configuration of an example of an image forming apparatus. The image forming apparatus 100 is a tandem type intermediate transfer type electrophotographic full-color printer in which four image forming units 1Y, 1M, 1C, and 1Bk are arranged along the downward surface of the intermediate transfer belt 8.

  In the image forming unit 1Y, a yellow toner image is formed on the photosensitive drum 2a and transferred to the intermediate transfer belt 8. In the image forming unit 1M, a magenta toner image is formed on the photosensitive drum 2b and transferred to the intermediate transfer belt 8. In the image forming units 1C and 1Bk, a cyan toner image and a black toner image are formed on the photosensitive drums 2c and 2d, respectively, and transferred to the intermediate transfer belt 8.

  Thus, a superimposed toner image in which the above four color toner images are sequentially superimposed is formed on the intermediate transfer belt 8, and the superimposed toner image is conveyed to the secondary transfer portion T2 by the subsequent rotation of the intermediate transfer belt 8. Batch transfer is performed onto the recording material P. The recording material P on which the superimposed toner image is secondarily transferred is heated and pressed by the fixing device 16 to fix the toner image on the surface, and then discharged to the upper tray 17 through the discharge roller 15.

  The separation roller 19 separates the recording material P drawn from the recording material cassette 18 one by one and sends it to the registration roller 14. The registration roller 14 receives and waits for the recording material P in a stopped state, and sends the recording material P to the secondary transfer portion T2 in time with the toner image on the intermediate transfer belt 8.

  The fixing device 16 presses the pressure roller 16b against the fixing roller 16a provided with a heater to form a heating nip (fixing nip). The recording material P is heated and pressurized at the heating nip to melt the toner image and fix the full color image on the surface.

  The image forming units 1Y, 1M, 1C, and 1Bk are configured substantially the same except that the color of toner used in the developing devices 4a, 4b, 4c, and 4d is different from yellow, magenta, cyan, and black.

  Hereinafter, the image forming unit 1Y will be described as a representative, and the other image forming units 1M, 1C, and 1Bk will be described by replacing “a” at the end of the reference code with “b”, “c”, and “d”. . The image forming unit 1Y surrounds the photosensitive drum 2a and includes a charging roller 3a, an exposure device 7, a developing device 4a, a primary transfer roller 5a, and a cleaning device 6a. The photosensitive drum 2a has a negatively charged photosensitive layer formed on the outer peripheral surface of an aluminum cylinder. The photosensitive drum 2a is rotated at a predetermined process speed in the clockwise direction indicated by an arrow when a driving force is transmitted from a driving motor (not shown). To do.

  The charging roller 3a is driven to rotate by the photosensitive drum 2a and charges the photosensitive drum 2a to a uniform negative potential by applying an oscillating voltage obtained by superimposing an alternating voltage on a negative direct current voltage. The exposure device 7 scans the scanning line image data obtained by developing the yellow separation color image in the color image with a rotating mirror, and writes an electrostatic image of the image on the surface of the charged photosensitive drum 2a. . The developing device 4a transfers the toner to the photosensitive drum 2a and develops the electrostatic image into a yellow toner image.

  The primary transfer roller 5 a presses the intermediate transfer belt 8 to form a primary transfer portion Ta between the photosensitive drum 2 a and the intermediate transfer belt 8. By applying a positive DC voltage to the primary transfer roller 5a, a negative yellow toner image carried on the photosensitive drum 2a is primarily transferred to the intermediate transfer belt 8 passing through the primary transfer portion Ta. The cleaning device 6a removes the transfer residual toner adhering to the surface of the photosensitive drum 2a that has passed through the primary transfer portion Ta by sliding the cleaning blade on the photosensitive drum 2a.

  The intermediate transfer belt 8 is supported around a tension roller 11, a driving roller 10 that also serves as a secondary transfer counter roller, and a stretching roller 13, and is driven by the driving roller 10 to rotate in the counterclockwise direction indicated by an arrow R2. It rotates at a peripheral speed corresponding to the rotational peripheral speed of 2a.

  The secondary transfer portion T <b> 2 is configured by bringing the secondary transfer roller 12 into contact with the intermediate transfer belt 8 whose inner surface is stretched by the driving roller 10. By applying a positive DC voltage to the secondary transfer roller 12, a transfer electric field for the toner image is formed between the secondary transfer roller 12 and the driving roller 10 connected to the ground potential. The belt cleaning device 9 rubs the intermediate transfer belt 8 with a cleaning blade to remove the transfer residual toner attached to the surface of the intermediate transfer belt 8 that has passed through the secondary transfer portion T2.

  Below the developing devices 4a, 4b, 4c, and 4d, toner bottles 70a, 70b, 70c, and 70d are disposed as toner containers, respectively. The toner consumed by the developing devices 4a, 4b, 4c, and 4d by the image formation is replenished by toner replenishing devices described later from the toner bottles 70a, 70b, 70c, and 70d, respectively.

<Developing device>
FIG. 2 is a schematic diagram for explaining the developing device 4a, the toner replenishing device 301 for the developing device 4a, and the control system. 3, 4, and 5 are a partially cutaway perspective view, a cross-sectional view as viewed from the side, and a cross-sectional view as viewed from the rear, respectively, of the toner supply device 301. 2, 3, and 5 are views of the developing device 4 a and the toner replenishing device 301 of FIG. 1 as viewed from the rear side.

  The developing device 4a in this embodiment is a developing device that uses a two-component developer (non-magnetic toner + magnetic carrier), and is a horizontally long device along the longitudinal direction (rotation axis direction, generatrix direction) of the photosensitive drum 2a. is there. Here, in the apparatus of the present embodiment, the one end side (front side) in the longitudinal direction of the constituent member is the front side (back side in FIG. 2) in FIG. 1, and the other end side (rear side) is On the other side.

  As shown in FIG. 2, the developing device 4a includes a developing container (developer storage part) 41, a developing sleeve 42 as a developer carrier disposed in the developing container 41, a developing screw 43, A stirring screw 44 is provided. A magnet roller 45 is installed in the developing sleeve 42 in a non-rotating state. A predetermined amount of two-component developer (not shown) made of toner (non-magnetic) and carrier (magnetic) is stored (filled) in the developing container 41.

  The developing sleeve 42 is disposed so as to be rotatable in parallel with the photosensitive drum 2a and close to the photosensitive drum 2a with a predetermined slight gap. The developing screw 43 is disposed below the developing sleeve 42 so as to be parallel to the developing sleeve 42 and in a predetermined proximity to the developing sleeve 42 so as to be rotatable. The agitating screw 44 is disposed on the side of the developing screw 43 and at a position farther from the developing sleeve 42 than the developing screw 43, in parallel with the developing screw 43 and rotatably.

  The developing sleeve 42 is driven to rotate around the outer periphery of the magnet roller 45 at a predetermined peripheral speed in the forward direction in the rotation direction of the photosensitive drum 42 at the developing portion D that is a portion facing the photosensitive drum 42. The developing screw 43 and the stirring screw 44 are also driven to rotate at a predetermined speed and rotation direction, respectively.

  By rotating the agitating screw 44, the two-component developer around the screw is conveyed while being agitated from the other end side in the longitudinal direction of the developing container to the one end side in the developing container 41. Further, when the developing screw 43 is rotated, the two-component developer around the screw is conveyed while being stirred from one end side to the other end side in the developing container longitudinal direction in the developing container 41.

  By rotating the stirring screw 44 and the developing screw 43, the two-component developer in the developing container 41 circulates in the developing container 41 from the other end side in the longitudinal direction of the developing container to one end side and from one end side to the other end side. So that it is conveyed. As described above, in the process in which the two-component developer is circulated and conveyed in the developing container 41, the toner is frictionally charged to a predetermined polarity by the stirring contact with the carrier.

  A part of the two-component developer conveyed while being stirred along the developing screw 43 is supported on the surface of the developing sleeve 42 while being magnetically restrained as a developer layer by the magnetic force of the magnet roller 45. The developer is restrained by magnetically restraining the magnetic carrier. The developer layer is conveyed to the development site D by the rotation of the developing sleeve 42 and applied (supplied) to the photosensitive drum 2a.

  An oscillating voltage obtained by superimposing an AC voltage on a DC voltage is applied to the developing sleeve 42 as a developing bias from a developing bias applying power source 46. As a result, at the development site D, the toner in the two-component developer layer carried on the surface of the developing sleeve 42 is selectively transferred corresponding to the electrostatic image on the photosensitive drum 2a, and the electrostatic image is transferred. Developed as a toner image.

  The two-component developer layer on the developing sleeve 42 subjected to toner development of the electrostatic image at the developing portion D is conveyed back into the developing container 41 by the subsequent rotation of the developing sleeve 42. The returning developer layer is removed from the surface of the developing sleeve 42 by a peeling means (not shown: a magnetic peeling means or a physical peeling means such as a blade). The two-component developer removed from the surface of the developing sleeve 42 is mixed with the developer in the developing container 41. A fresh two-component developer layer is again formed and supported on the surface of the developing sleeve from which the developer layer has been peeled off by magnetic restraint.

<Toner supply device>
The toner of the two-component developer in the developing container 41 is consumed by image formation (electrostatic image development), and the ratio of the toner amount to the carrier amount decreases. In development with a two-component developer that has high image quality and low running costs, it is desirable to always keep the ratio between the carrier amount and the toner amount of the two-component developer in the developing container 41 substantially constant. The toner replenishing device 301 serves to keep the ratio of the amount of carrier and the amount of toner in the developing device 4a almost constant by appropriately supplementing the toner in the developing device consumed by the image formation.

  As the image is formed, the toner is transferred from the two-component developer to the photosensitive drum 2a and consumed, so the control unit (control means) 50 is only consumed in the previous image formation for each image formation. The toner replenishing device 301 is controlled so that the toner is replenished into the developing container 41.

  Further, if toner is replenished for each image formation, errors accumulate, and the two-component developer in the developer container 41 has a toner concentration (weight ratio of toner in the two-component developer) in an appropriate range. May deviate. Therefore, the control unit 50 maintains the toner concentration of the two-component developer in the developing container 41 within a predetermined concentration range, for example, 8 to 10% based on the output of the toner concentration sensor (magnetic permeability sensor) 47. Thus, the toner replenishing device 301 is controlled.

  In this embodiment, the toner replenishing device 301 is disposed on the other end side in the longitudinal direction of the developing device 4a (the back side of the image forming apparatus). The toner replenishing device 301 has a toner storage portion 302 as a storage portion for storing toner supplied from a toner bottle 70a as a toner container disposed at a lower position in the direction of gravity than the developing device 4a. In addition, the toner storage unit 302 includes a toner transport unit 303 that is an example of a transport unit that pumps and transports the toner stored in the toner storage unit 302 toward the developing container 41 of the developing device 4 a located higher than the toner storage unit 302.

  In the toner bottle 70a in this embodiment, a cylindrical container is filled with toner. A cylindrical opening 71 concentric with the container axis is provided on one end face side of the container. The opening 71 is normally closed by a sealing member (not shown) to prevent internal toner leakage. The toner bottle 70a is mounted on a predetermined mounting portion of the main body of the image forming apparatus in a predetermined mounting manner with the opening 71 side facing the toner replenishing device 301 and the container axis parallel to the longitudinal direction of the developing device 4a. The

  When the toner bottle 70a is mounted on the main body of the image forming apparatus in a predetermined manner, the lower surface of the toner bottle 70a rides on two parallel support rollers 18 (FIG. 2) of the mounting portion and is rotatably held around the container axis. Has been. Also. As shown in FIG. 4, the opening 71 of the toner bottle 70 a is held in a state of being pressed against the toner receiving port 302 a provided on the front end surface of the toner storage unit 302 of the toner supply device 301. In this state, the sealing of the sealing member in the opening 71 is released, and the opening 71 and the toner receiving port 302a are in communication with each other. In addition, the sealing release structure of the sealing member is omitted in the drawing.

  The toner bottle 70a is driven to rotate at a predetermined speed in the counterclockwise direction indicated by an arrow in FIG. 2 around the container axis by driving a bottle motor 51 controlled by the control unit 50. An inclined partition wall structure 72 (FIG. 4) for sequentially discharging the toner in the toner bottle 70a from the opening 71 as the toner bottle 70a rotates is disposed inside the toner bottle 70a.

  As the toner bottle 70a rotates, the toner sequentially discharged from the opening 71 drops by gravity into the toner reservoir 302 through the toner receiving port 302a that is in communication with the opening 71 and communicates therewith. Supply (discharge). As a result, toner accumulates in the toner reservoir 302. That is, the toner storage unit 302 stores the toner supplied from the toner bottle 70a. A seal structure (not shown) is provided so that the toner does not leak from a matching connection (meeting part) between the opening 71 of the toner bottle 70a and the toner receiving part 302a of the toner storage part 302.

  Two parallel coil screws 313 and 314 are disposed at the bottom of the toner storage portion 302 and flow while stirring the toner from one end side on the toner receiving port portion 302a side toward the other end side opposite thereto. Yes. Further, a toner discharge port 306 is disposed at a meeting portion between the side wall and the bottom wall on one side of the toner storage portion 302 on the other end side of the toner storage portion 302.

  While the bottle motor 51 is being driven, the coil screws 313 and 314 are driven by the driving force of the bottle motor 51 via the one-way clutch 316 and rotated in a predetermined direction R3 at a predetermined speed. Further, while the toner conveying motor 52 is being driven, the coil screws 313 and 314 are also driven to rotate in a predetermined direction at a predetermined speed by transmitting the driving force of the toner conveying motor 52 via the one-way clutch 317. The

  As the toner bottle 70a rotates, the toner supplied to the toner storage unit 302 and the toner stored in the toner storage unit 302 are agitated by the rotating coil screws 313 and 314 to improve fluidity. Then, the toner reservoir 302 flows from one end to the other end, and the surface of the toner reservoir in the toner reservoir 302 is kept substantially flat.

  The toner storage unit 302 includes detection means for detecting the toner amount level of the stored toner. In this embodiment, the detection means is an optical structure that optically detects the toner amount level as follows.

  A pair of light transmitting members 401 a and 401 b using an acrylic resin rod-like lens are disposed on the opposite side walls of the toner storage portion 302, with the inner end faces facing each other in the toner storage portion 302. An infrared light emitting diode 53 as a light source is disposed on the outer end surface of one light transmitting member 401a so as to face the light transmitting member 401a. A light receiving element (light receiving sensor) 54 is disposed facing the outer end surface of the other light transmitting member 401b.

  The light transmitting members 401 a and 401 b form an optical path 53 a in which the light emitted from the light emitting diode 53 (infrared ray: detection light) is incident on the light receiving element 54 in the toner reservoir 302. That is, the infrared light output from the light emitting diode 53 is emitted into the toner reservoir 302 through the light transmitting member 401a, and enters the light receiving element 54 through the light transmitting member 401b.

  The control unit 50 detects the light transmitted through the light transmitting members 401a and 401b and controls the supply of toner from the toner bottle 70a to the toner storage unit 302. That is, in order to realize stable toner supply from the toner storage unit 302 to the developing device 4a via the toner conveyance unit 303, a predetermined substantially constant amount of toner is always stored in the toner storage unit 302. Is desired.

  Therefore, the control unit 50 detects the toner amount (toner amount level: storage amount) of the toner storage unit 302 according to the transmission / light shielding of the optical path 53a in the toner storage unit 302, and the toner bottle according to the detection result. The toner supply from the toner storage unit 302 to the toner storage unit 302 is controlled.

  That is, when the light path 53 a is blocked by the toner reservoir stored in the toner reservoir 302 and the light from the light emitting diode 53 is not detected by the light receiving element 54, the controller 50 determines the toner amount level of the toner reservoir 302. Is determined to be at a predetermined level. In this case, control is performed to stop the rotation of the toner bottle 70a and stop the supply of toner from the toner bottle 70a to the toner storage unit 302.

  Further, when the light receiving element 54 receives infrared light (detection light) output from the light emitting diode 53, the control unit 50 determines that the toner amount level in the toner storage unit 302 has decreased below a predetermined level. . In this case, control is performed to start the supply of toner from the toner bottle 70a to the toner reservoir 302 by rotating the toner bottle 70a.

  When the toner amount level of the toner storage unit 302 increases due to this toner supply, the optical path 53 a is blocked by the toner storage stored in the toner storage unit 302, and the light from the light emitting diode 53 is not detected by the light receiving element 54. . Accordingly, the control unit 50 determines that the toner amount level of the toner storage unit 302 has recovered to a predetermined level, stops the rotation of the toner bottle 70a, and supplies toner from the toner bottle 70a to the toner storage unit 302. Control to stop.

  As described above, the control unit 50 controls the supply of toner from the toner bottle 70a to the toner storage unit 302 and the supply stop so that the toner amount level in the toner storage unit 302 is maintained at a predetermined substantially constant level. That is, the control unit 50 adjusts the amount of toner taken out from the toner bottle 70a so that the toner amount level in the toner storage unit 302 is maintained at a predetermined substantially constant level.

  The toner conveying unit 303 includes a cylindrical pipe 304 and a toner conveying screw 305 inserted through a hollow portion of the pipe 304. The screw 305 has a shaft whose upper end and lower end are rotatably supported with respect to the upper end and lower end of the pipe 304, respectively. A toner receiving hole 304 a is provided on the side surface of the pipe 304 on the lower end side. Further, a toner discharge hole 304b is provided on the side surface of the pipe 304 on the upper end side.

  A toner receiving hole 304 a on the lower end side of the pipe 304 of the toner transport unit 303 is fitted and engaged with the toner discharge port 306 of the toner storage unit 302 and connected to the toner storage unit 302. Further, the toner discharge hole 304b on the upper end side of the pipe 304 of the toner transport unit 303 is fitted and engaged with the toner receiving hole 41b on the developing container 41 side of the developing device 4a and connected to the developing container 41.

  In the present embodiment, the toner receiving hole 41b on the developing container 41 side is provided with respect to the extended cylindrical portion 41a provided so as to protrude to the rear end side of the developing container 41. The other end side of the stirring screw 44 in the developing container 41 is extended inside the extended cylindrical portion 41a.

  A drive gear G1 is fixed to the lower end portion of the shaft of the toner conveying screw 305. The driving force of the toner transport motor 52 controlled by the control unit 50 is transmitted to the gear G1 via the relay gear G2. As a result, the toner conveying screw 305 is rotationally driven in a predetermined direction at a predetermined speed.

  By the rotation of the toner conveyance screw 305, the toner conveyance unit 303 takes out the toner stored in the toner storage unit 302 from the discharge port 306 to the lower end portion in the pipe 304 and moves the upper portion in the pipe 304 toward the developing device 4a. Transport to. Then, the toner is supplied from the toner discharge hole 304b at the upper end of the pipe into the extended cylindrical portion 41a on the rear end side of the developing container 41. The toner replenished in the extension cylindrical portion 41a is taken into the developing container 41 by the rotation of the extension portion on the other end side of the stirring screw in the extension cylindrical portion 41a and is circulated and conveyed in the developing container 41. It diffuses in the agent.

  That is, the toner replenishing device 301 takes out the toner taken out from the toner bottle 70a and stored in the toner storage unit 302 from the discharge port 306 by the toner transport unit 303, and pumps up the toner to the developing device 4a with a controlled supply amount. In order to adjust the toner replenishment amount of the toner transport unit 303, it is essential that the pipe 304 is always filled with toner.

  In order to precisely control the amount of toner supplied from the toner storage unit 302 to the developing device 4a via the toner conveying unit 303, toner having a stable “bulk density” is developed according to the rotation angle of the screw 305. It is desirable to be supplied to. In order to supply toner having a stable bulk density to the developing device 4a, the toner bulk density of the toner in the vicinity of the toner discharge port 306 of the toner reservoir 302 is stabilized to the screw 305. It is desirable to feed toner stably and continuously.

  Therefore, as described above, the toner replenishing device 301 according to the present exemplary embodiment stirs the toner stored in the toner storage unit 302 with the coil screws 313 and 314 to increase the fluidity, The surface is kept substantially flat.

  The control unit 50 confirms that the toner concentration of the two-component developer in the developing container 41 has returned to the predetermined concentration range by supplying toner from the toner storage unit 302 to the developing device 4a via the toner conveying unit 303. When detected by the toner density sensor 47, the motor 52 is stopped. That is, the operation of the toner conveyance unit 303 is stopped, and the operation of supplying toner from the toner storage unit 302 to the developing device 4a is stopped.

  In this embodiment, the vibration generating unit 415 that generates vibration by driving the motor 52 is provided, and the vibration of the vibration generating unit 415 is transmitted to the light transmitting members 401 a and 401 b via the vibration transmitting unit 402. It is. By adopting a configuration in which the light transmitting members 401a and 401b are vibrated, the toner attached to the inner end surfaces of the light transmitting members 401a and 401b is shaken off, and the optical detection accuracy at the toner amount level is maintained.

<Toner bottle rotation start timing of comparative method>
In the comparative example method, when light from the light emitting diode 53 is detected by the light receiving element 54, the toner storage unit 302 determines that the toner amount level has decreased below a predetermined level and starts rotating the toner bottle 70a. That is, the supply of toner from the toner bottle 70a to the toner storage unit 302 is started.

  As the toner is supplied, the toner amount level in the toner reservoir 302 increases, and the surface of the toner reservoir reaches the optical path 53a between the light transmitting member 401a and the light transmitting member 401b, thereby blocking the optical path 53a. Then, the light from the light emitting diode 53 is not detected by the light receiving element 54. Accordingly, the control unit 50 determines that the toner amount level of the toner storage unit 302 has recovered to a predetermined level, stops the rotation of the toner bottle 70a, and supplies toner from the toner bottle 70a to the toner storage unit 302. Stop.

  As described above, the control unit 50 rotates the toner bottle 70 a until the detection light from the light emitting diode 53 is not detected by the light receiving element 54 to replenish new toner in the toner storage unit 302, and Increase toner level.

  When the toner concentration sensor 47 detects that the toner concentration of the two-component developer in the developing container 41 in the developing device 4a is lower than a predetermined concentration threshold, the controller 50 operates the motor 52. As a result, the screw 305 of the toner conveying unit 303 is rotationally driven, and the toner in the toner storage unit 302 is pumped up to the developing device 4a. In the developing device 4a, new toner is taken out from the toner bottle 70a and temporarily stored in the toner storage unit 302, and then supplied to the developing device 4a by a screw 305 by a necessary amount.

  However, in this comparative example method, the toner is clogged in the path for discharging and transporting the toner to the developing device 4a with a durability of 300,000 sheets in a high temperature and high humidity environment. The location where this toner clogging occurred was the toner discharge port of the conveying means. In a high temperature and high humidity environment, the adhesion of the toner increased and a toner immobile layer was generated on the wall surface of the discharge port.

  Further, it has been found that the reason why the adhesion force of the toner is increased is related to the toner bulk density in the toner storage unit 302 which is a storage unit in order to stabilize the amount of toner supplied to the developing device 4a. As a result of increasing the bulk density, a small amount of the wax component added to the toner surface in the vicinity of the surface of the toner to improve the fixing property, and the tendency to ooze out especially in a high temperature and high humidity environment. .

<Toner bottle rotation start timing of this embodiment>
On the other hand, in this embodiment, a method for controlling the toner bulk density in the toner storage unit 302 so as not to be raised excessively is used for such a problem. This will be described below. FIG. 6 shows a control flow, and FIG. 7 shows a control system block.

  In this embodiment, when the light from the light emitting diode 53 is detected by the light receiving element 54, the control unit 50 determines that the toner amount level has decreased below a predetermined level (no toner) in the toner storage unit 302 (FIG. 6: No in step S1).

  In this embodiment, the rotation of the toner bottle 70a is not immediately started here. That is, even if the absence of toner is detected in step S1, toner supply from the toner bottle 70a to the toner storage unit 302 is not started by the detection signal (yes in S1 → S6). After the light is detected by the light receiving element 54, the toner in the transport unit (in the toner supply device 301) is consumed more than a certain amount. The rotation of the toner bottle 70a is started for the first time after the predetermined amount operation by the conveying means 303 (No in S2 → S3). Here, the predetermined amount operation indicates a predetermined number of rotations of the screw 305.

  In this embodiment, when the cumulative supply counter 55 (FIG. 7) reaches 5 rotations, the rotation of the toner bottle 70a is started and the toner supply from the toner bottle 70a to the toner storage unit 302 is started (No in S2 → S3). When the cumulative supply counter 55 is 4 rotations or less, the toner supply from the toner bottle 70a to the toner storage unit 302 is not started (yes in S2 → S6).

  The control unit 50 determines that the toner amount level in the toner storage unit 302 has recovered to a predetermined level (there is toner) when the light is not detected by the light receiving element 54 due to toner supply in step S3 (Yes in S4). Then, the cumulative supply amount counter 55 by the screw 305 is reset (S5), and the rotation of the toner bottle 70a is stopped. That is, the toner supply from the toner bottle 70a to the toner storage unit 302 is stopped (S6).

  In this way, after the control unit 50 detects that the detection units 53 and 54 are less than the predetermined level with respect to the toner amount level, the control unit 50 operates the transport unit 303 by a predetermined amount to replenish the developing device 4 with a predetermined amount of toner. Toner is supplied to the toner storage unit 302. That is, the toner supply from the toner bottle 70a to the toner storage unit 302 is executed until the toner amount level in the toner storage unit 302 recovers to a predetermined level.

  FIG. 8 shows the relationship between the amount of replenishment per rotation that is supplied from the discharge port to the developing device 4a after waiting for a predetermined number of rotations of the screw 305, and the durable number of sheets until the occurrence of toner clogging in a high temperature and high humidity environment. According to this, by starting the rotation of the toner bottle 70a after the screw 305 has rotated five times or more, occurrence of toner clogging can be suppressed to about 440,000 sheets. Since the main body life of the image forming apparatus in the present embodiment is 400,000 sheets, this can prevent toner clogging.

  Concentration fluctuation is a concern as an adverse effect of 5 revolutions or more. However, it has been confirmed that even if the replenishment amount per block decreases by about 20%, the replenishment frequency to the developing device 4a is increased, so that there is almost no influence.

  On the other hand, in a normal environment or in a low-temperature and low-humidity environment, control may be performed so that productivity does not decrease for an image with a high printing rate by lowering the threshold value by two rotations or more.

  According to the present embodiment as described above, it is possible to suppress toner clogging at the toner discharge port from the storage portion through durability while stably supplying toner to the developing device 4a.

[Example 2]
The image forming apparatus according to the second embodiment has a main body life of 500,000 sheets, which is further improved from the first embodiment. Therefore, as a configuration of the toner replenishing device according to the second exemplary embodiment, in addition to the first exemplary embodiment, by adjusting the minimum rotational speed of the replenishing operation by the screw 305, the toner clogging that occurs through the durability is further improved. Below, the control method in the present Example 2 is demonstrated.

  FIG. 9 shows the relationship between the minimum rotation speed of the screw 305 and toner clogging. From the experimental results, it was found that the minimum number of rotations of the screw 305 has an influence. The reason for this will be described next.

  The screw 305 is driven using a general DC motor as a drive source. When the minimum number of rotations of the screw 305 is controlled every rotation, the rotation of the screw is controlled in the motor start-up region, so that the control is performed in a very slow region. This promoted toner clogging.

  On the other hand, it was found that the toner clogging can be suppressed by setting the minimum rotation number of the screw 305 to 3 rotations or more. In the second embodiment, the toner bottle rotation start timing is set to 5 rotations or more after the light detection by the light receiving sensor 54, and further, the minimum rotation number of the screw 305 is set to 3 rotations. And the main unit life of 500,000 sheets has been achieved.

  The balance with the control that suppresses the density fluctuation is more balanced, and toner clogging is unlikely to occur in a normal environment where the toner clogging is unlikely to occur or in a low temperature and low humidity environment.

  According to the second embodiment as described above, it is possible to suppress toner clogging at the toner discharge port from the storage portion through durability while stably supplying toner to the developing device 4a.

  In Examples 1 and 2, the toner may be a toner in a one-component developer instead of a toner in a two-component developer.

  1 (Y, M, C, Bk): image forming unit, 2 (a, b, c, d): photosensitive drum, 4 (a, b, c, d): developing device, 41: developing container, 42: Development sleeve, 50: control unit, 51/52: motor, 53: light emitting diode, 54: light receiving element, 70 (a, b, c, d): toner bottle, 301: toner replenishing device, 302: toner storage unit, 303: Toner conveying unit, 305: Screw, 306: Discharge port, 313/314: Coil screw, 316/317: One-way clutch, 401 (a / b): Light transmitting member

Claims (6)

A toner replenishing device for the developing device,
A storage unit for storing toner supplied from the toner container;
Conveying means for conveying the toner stored in the storage unit toward the developing device;
Detecting means for detecting a toner amount level of toner stored in the storage unit;
After the detecting means detects that the toner amount level is less than a predetermined level, the toner amount level is restored to the predetermined level after the conveying means is operated for a predetermined amount to supply a predetermined amount of toner to the developing device. Control means for executing the toner supply from the toner container to the storage unit,
A toner replenishing device.   The detection means includes a light transmission member that forms an optical path for detecting toner stored in the storage unit by positioning an end surface inside the storage unit, a light source, and the light transmission member through the end surface. The toner replenishing device according to claim 1, further comprising: a light receiving element that detects the light of the transmitted light source.   The toner replenishing device according to claim 1 or 2, wherein the predetermined amount of operation is the number of rotations of a toner conveying screw of the conveying unit.   The toner replenishing device according to claim 3, wherein a minimum number of rotations when the toner conveying screw rotates is at least two or more.   The toner replenishing device according to any one of claims 1 to 4, wherein the toner is toner in a two-component developer.   The toner replenishing device according to claim 1, wherein the toner is toner in a one-component developer.