JP2010032890A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device and an image forming apparatus for inexpensively preventing adhesion of toner in a toner conveyance path between a toner bottle and a developing unit. <P>SOLUTION: The image forming apparatus 100 is provided with the toner conveyance path 13 connecting a toner hopper part 12 and a toner buffer part 14. The apparatus 100 is provided with a conveying member 15 conveying the toner from the toner hopper part 12 to the toner conveyance path 13, and a conveying member 16 conveying the toner from the toner conveyance path 13 to the toner buffer part 14. When stopping conveyance of the toner from the toner hopper part 12 to the toner buffer part 14, conveying operation of the conveying member 15 is stopped, and conveyance of the toner in the conveyance path 13 to the toner buffer part 14 is finished, and then conveying operation of the conveying member 16 is stopped. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image on a sheet, and more particularly to an image forming apparatus in which a toner bottle and a developing device are connected by a toner conveyance path.

  Conventionally, high-productivity image forming apparatuses often use large-capacity toner bottles due to the large amount of toner consumed. However, it is difficult to arrange toner bottles inside the apparatus because of space. It was. In this case, due to the configuration of the apparatus, the toner bottle is disposed at a position away from the developing device, and the toner is transported by connecting the toner bottle and the developing device with a pipe-shaped toner transport path.

  However, in such an image forming apparatus, the heat generated from the fixing device 7 provided inside the apparatus affects the toner in the toner conveyance path. In this case, since it is affected by heat from the entire circumference of the pipe-shaped toner conveyance path, the temperature of the toner in the toner conveyance path tends to be higher than the toner in the toner bottle and the developing device.

  When the toner stays in the conveyance path at a high temperature, the toner melts and adheres to the conveyance path. Particularly in recent years, there is a tendency to use toner having a low melting point from the viewpoint of energy saving and efficiency, and it is desirable not to apply excessive heat to the toner.

Therefore, as a technique for suppressing the temperature rise of the toner in the image forming apparatus, there is a technique that provides a cooling fan (Patent Document 1) or a technique that suppresses the temperature rise by using a developer stirring and conveying member as a high heat conductive member such as a heat pipe. It has been proposed (Patent Document 2).
JP 2000-305344 A JP 2002-278386 A

  However, when a cooling fan is added as in Patent Document 1, not only the cost is increased, but there is a problem that noise is generated by the rotation of the cooling fan. There is also a problem that extra power is required to rotate the cooling fan.

  Further, when the material of the developer agitating / conveying member is a high heat conducting member such as a heat pipe as in Patent Document 2, there is a problem that the cost increases.

  SUMMARY An advantage of some aspects of the invention is that it provides a developing device and an image forming apparatus that can prevent toner from sticking in a toner conveyance path between a toner bottle and a developing device at low cost.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a first storage unit that stores a developer, a second storage unit that stores a developer, the first storage unit, and the second storage unit. A developer transport path connecting the storage means, a first transport means for transporting the developer from the first storage means to the developer transport path, and a second storage means from the developer transport path. The developer is transported from the first storage means to the second storage means through the developer transport path by the second transport means for transporting the developer to the first transport means and the first and second transport means. At the same time, when the conveyance is stopped, after the conveyance operation of the first conveyance unit is stopped, the developer in the developer conveyance path is transferred to the second storage unit by the second conveyance unit. After the operation for carrying, the control means for stopping the carrying operation of the second carrying means And having a, the.

  The image forming apparatus according to the present invention includes a first storage unit that stores a developer, a second storage unit that stores the developer, the first storage unit, and the second storage unit. A developer conveyance path to be connected, a first conveyance means for conveying the developer from the first storage means to the developer conveyance path, and a developer conveyance from the developer conveyance path to the second storage means Developer is transported from the first storage means to the second storage means through the developer transport path by the second transport means, and the first and second transport means. When the operation is stopped, the second transfer means is stopped in response to a lapse of a predetermined time after the transfer operation of the first transfer means is stopped after the transfer operation of the first transfer means is stopped. And a control means for stopping the transfer operation.

  According to the present invention, it is possible to provide an image forming apparatus capable of preventing the fixing of the developer in the developer transport path between the first storage unit and the second storage unit at a low cost. .

(First embodiment)
FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to the present embodiment.

  In FIG. 1, an image forming apparatus 100 is provided with a photosensitive drum 1 as an image carrier that is rotatable. Around the photosensitive drum 1, a charger 2, a laser exposure unit 3, and a developing unit 4 are arranged.

  The reader unit 200 is a device that reads an image of a document and outputs an image signal. The image signal output from the reader unit 200 is converted into an optical signal by the laser exposure unit 3, and the laser beam converted into the optical signal is reflected by the polygon mirror, and irradiated to the photosensitive drum 1 through the lens and each reflection mirror. Is done.

  When image formation is performed, the photosensitive drum 1 rotates, the charger 2 uniformly charges the surface of the photosensitive drum 1, and then the laser exposure unit 3 irradiates the photosensitive drum 1 with the laser light. A latent image is formed on the top. Next, the latent image on the photosensitive drum 1 is developed with a developer (toner) by the developing device 4 to form a toner image on the photosensitive drum 1.

  Here, the toner is replenished to the developing device 4 from the toner storage unit 10 in which the toner bottle 11 is stored through the toner hopper unit 12, the toner transport path 13 as a developer transport path, and the toner buffer unit 14.

  On the other hand, the recording medium is conveyed one by one from the storage unit 5 by the paper feed roller, and is conveyed to the transfer unit 6 at a desired timing. The recording medium on which the toner image is transferred by the transfer unit 6 is heated and fixed by a fixing device 7 having a heat roller, and is discharged to a paper post-processing device such as a paper discharge tray 8 or a finisher.

  When images are formed on both sides of the recording medium, after the recording medium passes through the fixing device 7, the conveyance path switching guide 19 is driven to guide the recording medium to the reversing path 20 and convey it to the reversing roller 21. . Then, the reverse roller 21 is reversely rotated to reverse the conveyance direction, and the recording medium is sent to the duplex conveyance path 22. Thereafter, the recording medium that has passed through the double-sided conveyance path 22 is again transferred to the other side by the above-described image forming process.

  FIG. 2 is a diagram illustrating toner conveyance from the toner bottle to the developing device.

  A toner bottle 11 is stored in the toner storage unit 10, and a mechanism is provided to allow the user to replace the toner bottle when the toner in the toner bottle 11 runs out.

  The toner bottle 11 is rotatably provided, and the toner bottle 11 is driven to rotate by a motor 211. When the toner bottle 11 rotates, the toner inside is sequentially discharged from the opening provided in the toner bottle 11 and is conveyed to the toner hopper unit 12.

  The toner hopper unit 12 is a first storage unit that stores toner replenished from the toner bottle 11. A sensor 201 is provided in the toner hopper 12. When the sensor 201 detects the absence of toner, the motor 211 rotates the toner bottle 11 and replenishes toner from the toner bottle 11 to the toner hopper unit 12.

  Further, a toner agitating / conveying member 15 is provided in the toner hopper section 12 and is configured to operate by a motor 212. When the motor 212 is rotated forward, the toner in the toner hopper 12 is agitated. When the motor 212 is rotated backward, the toner is transported from the toner hopper 12 to the toner transport path 13.

  A toner agitation / conveyance member 16 is provided in the toner conveyance path 13, and the toner is conveyed to the toner buffer unit 14 while agitating the toner in the toner conveyance path 13 by driving the motor 213. The toner conveyance path 13 is provided above the fixing unit 7 and is inclined downward from the toner hopper unit 12 toward the toner buffer unit 14.

  A sensor 204 is provided at the outlet of the toner conveyance path 13. The sensor 204 is a sensor for determining whether toner remains in the toner conveyance path 13. If the sensor 204 does not detect toner even when the motor 213 is rotated for a predetermined time, the toner in the toner conveyance path 13 is detected. Is determined not to remain.

  The toner buffer unit 14 is a second storage unit that stores toner. A sensor 202 is provided in the toner buffer unit 14. When the sensor 202 detects the absence of toner, the toner stirring / conveying members 15 and 16 are operated by the motors 212 and 213 to replenish the toner from the toner hopper unit 12 to the toner buffer unit 14.

  In addition, a toner agitating / conveying member 17 is provided in the toner buffer unit 14, and the toner agitating member 18 is driven by a motor 214 to agitate the toner in the toner buffer unit 14, and to the developing device 4. Transports toner.

  The developing device 4 is a device for forming a toner image on the photosensitive drum 1. A sensor 203 is provided in the developing device 4. When the sensor 203 detects that there is no toner, the motor 214 operates the toner stirring / conveying member 17 to replenish the toner from the toner buffer unit 14 to the developing device 4.

  Further, a toner stirring member 18 is provided in the developing device 4, and a toner image is formed on the photosensitive drum 1 while stirring the toner in the developing device 4 by driving a motor 215.

  FIG. 3 is a control block diagram of the image forming apparatus.

  A CPU (Central Processing Unit) 301 is a control circuit that controls the image forming apparatus 100. The CPU 301 is connected to a ROM 302 that stores a control program, a RAM 303 that holds setting values necessary for control, an operation unit 304 that receives operation input from a user, a timer 305, and an ASIC 310. The ASIC 310 includes a motor control unit 311 for driving various motors, a high voltage control unit 312 for controlling high voltage such as development, charging, and transfer, and an I / O control unit 313 for controlling I / O of various sensors. Consists of.

  The motors 211 to 215 are controlled by the motor control unit 311. Output signals from the sensors 201 to 204 and the temperature sensor 306 are acquired by the I / O control unit 313.

  FIG. 4 is a flowchart showing toner supply control to the toner hopper.

  A control program for executing this flowchart is stored in the ROM 302 and executed by the CPU 301.

  The CPU 301 determines whether or not the user has instructed the start of the image forming operation from the operation unit 304 (S401). When an instruction to start an image forming operation is given, it is determined whether or not the sensor 201 is turned off in order to monitor the toner remaining state in the toner hopper 12 (S402). Here, when the remaining amount of toner is less than the position where the sensor 201 is provided, the sensor 201 is turned off.

  When the sensor 201 is off, the CPU 301 instructs the motor control unit 311 to turn on the motor 211 and turn on the motor 212 in the forward rotation direction to perform the stirring operation (S403). Thus, toner is replenished from the toner bottle 11 to the toner hopper unit 12.

  Next, the CPU 301 determines whether or not a predetermined time has elapsed since the start of toner supply in step S403 (S404). If the sensor 201 remains off even after a predetermined time has elapsed after the toner replenishment operation, the CPU 301 determines that there is no toner in the toner bottle 11 and the toner is displayed on the liquid crystal display screen on the operation unit 304. A warning to the effect that no longer exists is displayed (405).

  Even when the warning is being displayed, the image forming operation can be continued. This is because even if the toner in the toner bottle 11 runs out, toner still remains in the toner conveyance path 13, the toner buffer unit 14, and the developing device 4, and the image forming operation can be continued for a while. .

  Next, the CPU 301 determines whether or not image formation has been completed (S407). If the image formation has not ended, the process returns to step S402. If the image formation has ended, the control flow ends.

  In step S402, when the sensor 201 is turned on before the predetermined time has elapsed, the CPU 301 instructs the motor control unit 311 to turn off the motors 211 and 212, and stops the toner transport operation (S406).

  Then, the process proceeds to step S407 described above. If the image formation is not completed, the process returns to step S402. If the image formation is completed, the control flow is terminated.

  FIG. 5 is a flowchart illustrating toner supply control to the toner buffer unit.

  A control program for executing this flowchart is stored in the ROM 302 and executed by the CPU 301.

  The CPU 301 determines whether or not the user has instructed the start of the image forming operation from the operation unit 304 (S501). When an instruction to start an image forming operation is given, it is determined whether or not the sensor 202 is off in order to monitor the toner remaining state in the toner buffer unit 14 (S502). Here, when the remaining amount of toner is smaller than the position where the sensor 202 is provided, the sensor 202 is turned off.

  When the sensor 202 is off, the CPU 301 causes the motor control unit 311 to turn on the motor 212 in the reverse direction to perform the replenishment operation, turn on the motor 213, and turn on the motor 214 in the forward direction. An instruction to perform the stirring operation is issued (S503). Thus, toner is replenished from the toner hopper unit 12 to the toner buffer unit 14.

  Next, the CPU 301 determines whether or not a predetermined time has elapsed since the start of toner replenishment in step S503 (S504). If the sensor 202 remains off even after a predetermined time has elapsed, the CPU 301 determines that further image formation cannot be continued, and displays a warning that the toner has run out on the liquid crystal display screen on the operation unit 304. (S505). Thereafter, the CPU 301 interrupts the image forming operation (S506).

  In step S504, if the predetermined time has not elapsed since the start of toner replenishment, the CPU 301 determines whether or not image formation has ended (S512). If the image formation has not ended, the process returns to step S502. If the image formation has ended, the control flow ends.

  On the other hand, if it is determined in step S502 that the sensor 202 is on, the CPU 301 refers to the output signal of the temperature sensor 306 and determines whether or not the internal temperature exceeds a predetermined temperature (here, 50 ° C.). Is determined (S507). Here, the temperature sensor 306 is a sensor that detects the temperature in the image forming apparatus, and is preferably provided in the toner conveyance path 13.

If the in-machine temperature exceeds 50 ° C., the CPU 301 stops the motor 212 and starts the timer 305 (S508). Then, the CPU 301 determines whether or not the timer 305 has reached a predetermined count value and the time is up (S509).
The predetermined count value until the time is up is obtained by an experiment in advance so as to be the time required for the toner in the toner conveyance path 13 to be completely conveyed to the toner buffer unit 14 with the motor 212 stopped. Stored in the ROM 302. That is, the timer 305 measures the elapsed time from the stop of the toner transport operation of the transport member 15 until the toner in the toner transport path 13 is completely removed.

  After the timer 305 counts up, the CPU 301 turns off the motors 213 and 214 (S510). Then, it is determined whether or not the image formation is completed (S512). If the image formation is not completed, the process returns to step S502, and if the image formation is completed, the control flow is terminated.

  In this way, the temperature inside the machine is detected by the temperature sensor 306, and when the temperature inside the machine exceeds a predetermined temperature, control is performed so as not to leave toner in the toner carrying path 13, so Toner sticking can be prevented.

  On the other hand, if the toner is not always left in the toner conveyance path 13, the amount of toner supplied to the developing device 4 or the toner buffer unit 14 varies greatly. Therefore, it is desirable to leave the toner in the toner transport path 13 when the toner does not adhere.

  Therefore, in step S507, if the in-machine temperature does not exceed 50 ° C., the CPU 301 turns off the motors 212, 213, and 214 and performs the toner transport operation with the toner remaining in the toner transport path 13. Stop (S511).

  Then, the CPU 301 determines whether or not the image formation has ended (S512). If the image formation has not ended, the process returns to step S502, and if the image formation has ended, this control flow ends.

  FIG. 6 is a flowchart showing toner supply control to the developing device.

  A control program for executing this flowchart is stored in the ROM 302 and executed by the CPU 301.

  The CPU 301 determines whether or not the user has instructed the start of the image forming operation from the operation unit 304 (S601). When an instruction to start an image forming operation is given, the CPU 301 turns on the motor 215 in the motor control unit 311 to stir the toner in the developing device 4 (602).

  Next, the CPU 301 determines whether or not the sensor 203 is off in order to monitor the toner remaining state in the developing device 4 (S603). Here, when the remaining amount of toner is smaller than the position where the sensor 203 is provided, the sensor 203 is turned off.

  When the sensor 203 is off, the CPU 301 instructs the motor control unit 311 to turn on the motor 214 (S604). As a result, toner is replenished from the toner buffer unit 14 to the developing device 4.

  Next, the CPU 301 determines whether a predetermined time has elapsed since the start of toner replenishment in step S604 (S605). If the sensor 203 remains off even after a predetermined time has elapsed, the CPU 301 determines that further image formation cannot be continued and displays a warning that the toner has run out on the liquid crystal display screen on the operation unit 304. (S606). Thereafter, the CPU 301 turns off the motors 214 and 215 (S607), and interrupts the image forming operation (S608).

  In step S605, if the predetermined time has not elapsed since the start of toner replenishment, the CPU 301 determines whether image formation has ended (S610). If the image formation has not ended, the process returns to step S603. When the image formation is completed, the CPU 301 turns off the motor 215 (S611) and ends this control flow.

  On the other hand, if it is determined in step S603 that the sensor 203 is on, the CPU 301 turns off the motor 214 and stops the toner supply operation from the toner buffer unit 14 to the developing device 4 (S609). Then, the CPU 301 determines whether or not the image formation has been completed (S610). If the image formation has not been completed, the process returns to step S603. When the image formation is completed, the CPU 301 turns off the motor 215 to stop the stirring operation (S611), and ends this control flow.

(Second Embodiment)
In the first embodiment, the timer 305 is used to count the time until the toner in the toner conveyance path 13 is completely conveyed to the toner buffer unit 14. On the other hand, in the second embodiment, the presence or absence of toner in the toner transport path 13 is detected by the sensor 204 without using the timer 305, and the toner in the toner transport path 13 is completely transported to the toner buffer unit 14. It is configured to detect this.

  FIG. 7 is a flowchart illustrating toner supply control to the toner buffer unit according to the second embodiment of the present invention.

  A control program for executing this flowchart is stored in the ROM 302 and executed by the CPU 301.

  The processing from step S701 to step S707 is the same as the processing from step S501 to step S507 in FIG.

  In step S707, if the internal temperature exceeds 50 ° C., the CPU 301 turns off the motor 212 (S708). Then, the CPU 301 waits until the toner in the toner conveyance path 13 is completely conveyed to the toner buffer unit 14, that is, until the sensor 204 is turned off (S709). When the sensor 204 is turned off, the CPU 301 turns off the motors 213 and 214 (S710).

  Then, the CPU 301 determines whether or not the image formation is completed (S712). If the image formation has not ended, the process returns to step S702. If the image formation has ended, the control flow ends.

  On the other hand, if the internal temperature does not exceed 50 ° C. in step S707, the CPU 301 turns off the motors 212, 213, and 214 to leave the toner in the toner transport path 13 (S711). Then, the CPU 301 determines whether or not the image formation has ended (S712). If the image formation has not ended, the process returns to step S702, and if the image formation has ended, this control flow ends.

  According to the second embodiment, by using the sensor 204 as the developer detection means, it is detected that the toner in the toner transport path 13 is completely transported to the toner buffer unit 14 without using the timer 305. can do.

  FIG. 8 is a diagram showing the arrangement of sensors in the toner buffer unit.

  FIG. 8A shows the moment when the sensor 202 changes from a toner-free state to a toner-present state. At this time, all the toner in the toner conveyance path 13 is conveyed to the toner buffer unit 14 so that the toner does not melt and adhere in the toner conveyance path 13.

  FIG. 8B shows a state in which the toner in the toner transport path 13 has been sent to the toner buffer unit 14 from the state of FIG. As described above, the sensor 202 is disposed at a position where the toner buffer unit 14 does not become full even if all of the toner in the toner transport path 13 is sent immediately after detecting the toner presence state.

  FIG. 8C shows the moment when the sensor 202 changes from the presence of toner to the absence of toner. At this time, the toner in the toner hopper unit 12 is conveyed to the toner buffer unit 14 via the toner conveyance path 13.

  FIG. 8D shows a state in which the toner conveyed in the toner conveyance path 13 has started to reach the toner buffer unit 14. As described above, the sensor 202 is disposed at a position where the toner buffer unit 14 is not emptied after the toner-free state is detected during the image forming operation and before the toner buffer unit 14 is supplied with toner. Yes.

  As described above, according to the embodiment of the present invention, it is possible to prevent toner from sticking in the developer transport path, that is, in the toner transport path 13 at a low cost. If the predetermined temperature is not exceeded by the detection result of the temperature sensor 306, the toner transport operation is stopped while the toner remains in the toner transport path 13, so that the developer 4 or the toner buffer unit 14 is replenished. Fluctuations in toner amount can be reduced.

1 is a schematic sectional view of an image forming apparatus. FIG. 6 is a diagram illustrating toner conveyance from a toner bottle to a developing device. 2 is a control block diagram of the image forming apparatus. FIG. 4 is a flowchart illustrating toner supply control to a toner hopper in the first embodiment. 6 is a flowchart illustrating toner supply control to a toner buffer unit according to the first embodiment. 6 is a flowchart illustrating toner replenishment control for a developing device according to the first exemplary embodiment. 10 is a flowchart illustrating toner supply control to a toner buffer unit according to a second embodiment. FIG. 4 is a diagram illustrating an arrangement of sensors in a toner buffer unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 Developing device 10 Toner storage part 11 Toner bottle 12 Toner hopper part 13 Toner conveyance path 14 Toner buffer part 15 Conveyance member 16 Conveyance member 17 Conveyance member 18 Toner stirring member 100 Image forming apparatus 201 Sensor 202 Sensor 203 Sensor 204 Sensor 211 Motor 212 Motor 213 Motor 214 Motor 215 Motor 301 CPU
304 Operation unit 305 Timer 306 Temperature sensor

Claims (5)

First storage means for storing developer;
Second storage means for storing the developer;
A developer transport path connecting the first storage means and the second storage means;
First conveying means for conveying developer from the first storage means to the developer conveying path;
Second conveying means for conveying the developer from the developer conveying path to the second storage means;
When the developer is transported from the first storage means to the second storage means through the developer transport path by the first and second transport means, and when the transport is stopped, After stopping the conveying operation of the first conveying means, the second conveying means after the operation for conveying the developer in the developer conveying path to the second storing means by the second conveying means. Control means for stopping the conveying operation of
An image forming apparatus comprising: Measuring means for measuring an elapsed time from the stop of the transport operation of the first transport means;
The image forming apparatus according to claim 1, wherein the control unit stops the transport operation of the second transport unit when the time measured by the measurement unit reaches a predetermined time. A developer detecting means for detecting the presence or absence of the developer in the developer transport path;
The control means stops the conveying operation of the second conveying means when the developer detecting means detects that there is no developer in the developer conveying path. Item 2. The image forming apparatus according to Item 1. A temperature detecting means for detecting the temperature in the image forming apparatus;
The control means, when stopping transport of the developer from the first storage means to the second storage means, if the predetermined temperature is not exceeded by the detection result of the temperature detection means, The transport operation of the second transport unit is stopped without performing an operation for transporting the developer in the developer transport path to the second storage unit. The image forming apparatus according to 1. First storage means for storing developer;
Second storage means for storing the developer;
A developer transport path connecting the first storage means and the second storage means;
First conveying means for conveying developer from the first storage means to the developer conveying path;
Second conveying means for conveying the developer from the developer conveying path to the second storage means;
When the developer is transported from the first storage means to the second storage means through the developer transport path by the first and second transport means, and when the transport is stopped, Control means for stopping the transport operation of the second transport means in response to a lapse of a predetermined time after the transport operation of the first transport means is stopped after the transport operation of the first transport means is stopped. When,
An image forming apparatus comprising:

Images