JP6233185B2 - Developing apparatus, image forming apparatus, and developing apparatus control method - Google Patents

Description

  The present invention relates to an electrophotographic developing apparatus, an image forming apparatus, and a control method for the developing apparatus.

  Generally, in an electrophotographic image forming apparatus, the developing device includes a developer supply unit and a developing unit. The developer supply unit includes a developer container that stores a developer, and the developing unit includes a developing tank and a developing roller that temporarily stores the developer. In each of the developer container and the developing tank, there is a conveying member such as a screw type conveyor member. The developer moves from the developer container into the developer tank by the operation of the conveying member in the developer container.

  Further, it is known that the developer is less likely to be charged when the humidity of the environment is higher than when the humidity is low (see, for example, Patent Document 1). When the charge amount of the developer is insufficient, development failure tends to occur.

  The developing section transports the developer from the agitating chamber in the developing tank to the developing chamber, and a second feeding member supplies the developer from the developing chamber to the developing roller (developing sleeve). It is conceivable to include a conveying member. In this case, it is known to correct the operating speed of the first conveying member according to the temperature and humidity in the apparatus (see, for example, Patent Document 1).

  The developing device may include an intermediate hopper between the developer supply unit and the developing unit (see, for example, Patent Document 2). The intermediate hopper section includes an intermediate storage section that temporarily stores the developer supplied from the developer container, and the transport member that transports the developer while stirring in the intermediate storage section. In this case, the developer moves from the developer container to the developer tank through the intermediate container.

JP 2009-92911 A JP 2013-152357 A

  By the way, when the operation speed of the conveyance member in the developing tank is increased in order to promote charging of the developer, the developer may be excessively supplied to the developing roller.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device and an image which can suppress fluctuations in the charge amount of the developer by preventing the developer from being excessively supplied to the developing roller and promoting charging of the developer according to environmental changes. An object of the present invention is to provide a method for controlling a forming apparatus and a developing apparatus.

  A developing device according to one aspect of the present invention includes a developer supply unit, an intermediate hopper unit, a developing unit, a second passage restriction unit, and a control unit. The developer supply unit includes a developer container that contains a developer and a first transport member that transports the developer to the first passage while stirring the developer in the developer container. The intermediate hopper unit temporarily stores the developer supplied from the developer supply unit via the first passage, and conveys the developer to the second passage while stirring the developer in the intermediate storage unit. It has a 2nd conveyance member. The developing unit includes a developing tank that temporarily stores the developer supplied from the intermediate hopper through the second passage, a developing roller that supplies the developer in the developing tank to an image carrier, and the developing tank. And a third conveying member that conveys the developer to the developing roller while stirring. The second passage restriction unit is operable in a range from a restricted state in which the passage of the developer is restricted in the second passage to an unrestricted state in which the developer is not restricted. When the chargeability parameter indicating the chargeability of the developer is changed from a predetermined state to a state indicating that the developer is less likely to be charged, the control unit moves the second transport member to the second transport member. It is possible to execute charging promotion control that operates at a higher speed ratio with respect to the operation speed of the third conveying member and operates the second passage restriction unit from the non-restricted state to the restricted state.

  An image forming apparatus according to another aspect of the present invention includes the developing device and an image carrier to which the developer is supplied from the developing device.

  A developing device control method according to another aspect of the present invention is a developing device control method including the developer supply section, the intermediate hopper section, the developing section, and the second passage restriction section. The method includes an input step and a charge acceleration step. The input step is a step of inputting a chargeability parameter representing the chargeability of the developer. In the charging acceleration step, when the chargeability parameter is changed from a predetermined state to a state indicating that the developer is less likely to be charged, the operation speed of the third conveyance member is changed. And operating the second passage restriction unit from the non-restricted state to the restricted state.

  According to the present invention, a developing device and an image that can suppress fluctuations in the charge amount of the developer by promoting charging of the developer according to environmental changes while preventing the developer from being excessively supplied to the developing roller. It is possible to provide a method for controlling the forming apparatus and the developing apparatus.

FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the developing device according to the embodiment of the present invention. FIG. 3 is a schematic plan view of the first state of the second passage restriction portion in the developing device according to the embodiment of the present invention. FIG. 4 is a schematic plan view of the second state of the second passage restriction portion in the developing device according to the embodiment of the present invention. FIG. 5 is a schematic plan view of a third state of the second passage restriction portion in the developing device according to the embodiment of the present invention. FIG. 6 is a block diagram of related devices for developing device control in the image forming apparatus according to the embodiment of the present invention. FIG. 7 is a flowchart showing an example of the procedure of the developing device control method according to the embodiment of the present invention. FIG. 8 is a diagram showing an example of a developer chargeability estimation rule in the developing device control method according to the embodiment of the present invention. FIG. 9 is a diagram illustrating an example of a conveyance operation speed correction rule in the developing device control method according to the embodiment of the present invention. FIG. 10 is a diagram showing an example of a developer passage restriction rule in the developing device control method according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: It does not have the character which limits the technical scope of this invention.

[Schematic Configuration of Image Forming Apparatus 10]
The image forming apparatus 10 according to an embodiment of the present invention is an electrophotographic image forming apparatus. As shown in FIG. 1, the image forming apparatus 10 includes a sheet supply unit 2, a sheet conveyance unit 3, an image forming unit 4, an optical scanning unit 5, a fixing unit 6, a temperature sensor 801, and a humidity sensor 802 in a housing 100. And a control unit 8 and the like.

  The image forming apparatus 10 is, for example, a printer, a copier, a facsimile machine, or a multifunction machine. The multifunction machine has both the printer function and the copier function.

  The sheet supply unit 2 includes a sheet receiving unit 21 and a sheet sending unit 22. The sheet receiving portion 21 is configured to be able to stack a plurality of recording sheets 9. The recording sheet 9 is a sheet-like image forming medium such as paper, coated paper, postcard, envelope, and OHP sheet.

  The sheet feeding unit 22 rotates in contact with the recording sheet 9 to send the recording sheet 9 from the sheet receiving unit 21 toward the conveyance path 30.

  The sheet conveyance unit 3 includes a conveyance roller 31. The conveyance roller 31 conveys the recording sheet 9 supplied from the sheet supply unit 2 toward the image forming unit 4, and further, the recording sheet 9 after image formation is discharged from the discharge port of the conveyance path 30. The sheet is discharged onto the discharge tray 101.

  The image forming unit 4 forms an image on the surface of the recording sheet 9 that is supplied from the sheet feeding unit 22 and is moving along the conveyance path 30. The image forming unit 4 includes a drum-shaped photoreceptor 41, a charging device 42, a developing device 43, a transfer device 45, a cleaning device 47, and the like. The photoreceptor 41 is an example of an image carrier.

  The photoconductor 41 rotates and the charging device 42 charges the surface of the photoconductor 41 uniformly. Further, an electrostatic latent image is written on the surface of the photosensitive member 41 charged by scanning the laser beam with the optical scanning unit 5.

  The developing device 43 develops the electrostatic latent image by supplying a developer to the photoconductor 41. The developing device 43 includes a developer supply unit 11, an intermediate hopper unit 12, and a developing unit 13. The developer is a two-component developer containing, for example, a magnetic carrier and toner. For example, the carrier includes ferrite particles having magnetism and a coating resin on the surface thereof. It is also conceivable that the developer is a toner that does not contain the carrier.

  Between the developer supply part 11 and the intermediate hopper part 12, a first replenishment part 140 that forms a passage for the developer is provided. Between the intermediate hopper portion 12 and the developing portion 13, a second replenishing portion 150 that forms a passage for the developer is provided. Hereinafter, the passage of the first supply unit 140 is referred to as a first passage 14, and the passage of the second supply unit 150 is referred to as a second passage 15.

  The developing device 43 further includes a second passage restriction unit 17 provided in the second passage 15. In addition, the developing device 43 in the present embodiment also includes a first passage restriction unit 16 provided in the first passage 14.

  As shown in FIG. 2, the developer supply unit 11 includes a developer container 111, a first stirring member 112, a first transport member 113, and a developer supply driving unit 114.

  The developer container 111 is a container in which a first storage space 110 for storing the developer is formed. The developer container 111 is detachably attached to the casing 100 (main body) of the image forming apparatus 10. The first stirring member 112 is disposed in the developer container 111. The first conveying member 113 is disposed in the developer container 111 with a part thereof exposed to the outside. Accordingly, as the developer container 111 is mounted and removed, the first stirring member 112 and the first transport member 113 are also mounted and removed from the casing 100 (main body).

  The first agitation member 112 and the first conveyance member 113 are members that convey the developer in the developer container 111 while agitating by rotating. The first stirring member 112 mainly serves to stir the developer. At the same time, the first stirring member 112 transports the developer to a position near the first transport member 113 in the first accommodation space 110.

  The first transport member 113 transports the developer in the developer container 111 to the first passage 14 while stirring the developer. A first discharge port 1111 communicating with the first passage 14 is formed in the developer container 111. The developer conveyed by the first conveying member 113 falls from the first discharge port 1111 through the first passage 14.

  The developer supply drive unit 114 is a mechanism that rotationally drives the first stirring member 112 and the first transport member 113. In the present embodiment, the developer supply driving unit 114 can adjust the driving speeds of the first stirring member 112 and the first transport member 113. For example, the developer supply drive unit 114 includes a motor (not shown) and a gear mechanism that transmits the rotational force of the motor to the first stirring member 112 and the first transport member 113. Further, the developer supply driving unit 114 includes a known speed change mechanism for adjusting the driving speed.

  The intermediate hopper unit 12 includes an intermediate storage unit 121, a second stirring member 122, a second transport member 123, and an intermediate hopper driving unit 124. The intermediate accommodating portion 121 is formed with a first supply port 1210 communicating with the first passage 14 and the first discharge port 1111.

  The intermediate storage unit 121 is a container in which a second storage space 120 for storing the developer is formed. The intermediate storage unit 121 temporarily stores the developer supplied from the developer supply unit 11 via the first passage 14. The second stirring member 122 is disposed in the intermediate accommodating portion 121. The second transport member 123 is disposed in the intermediate accommodating portion 121 with a part thereof exposed to the outside.

  The second agitating member 122 and the second conveying member 123 are members that convey the developer in the intermediate accommodating portion 121 while being agitated by rotating. The second stirring member 122 mainly serves to stir the developer. At the same time, the second stirring member 122 transports the developer to a position near the second transport member 123 in the second storage space 120.

  The second conveying member 123 conveys the developer to the second passage 15 while stirring the developer in the intermediate accommodating portion 121. A second discharge port 1211 communicating with the second passage 15 is formed in the intermediate housing part 121. The developer conveyed by the second conveying member 123 falls from the second discharge port 1211 through the second passage 15.

  The intermediate hopper driving unit 124 is a mechanism that rotationally drives the second stirring member 122 and the second transport member 123. In the present embodiment, the intermediate hopper driving unit 124 can adjust the driving speeds of the second stirring member 122 and the second conveying member 123. For example, the intermediate hopper drive unit 124 includes a motor (not shown) and a gear mechanism that transmits the rotational force of the motor to the second stirring member 122 and the second transport member 123. Further, the intermediate hopper drive unit 124 includes a known speed change mechanism for adjusting the drive speed.

  The developing unit 13 includes a developing tank 131, a third conveying member 132, a developing roller 133, and a developing driving unit 134. A second supply port 1310 that communicates with the second passage 15 and the second discharge port 1211 is formed in the developing tank 131.

  The developer tank 131 is a container in which a third storage space 130 for storing the developer is formed. The developer tank 131 temporarily stores the developer supplied from the intermediate hopper 12 through the second passage 15. The third transport member 132 is disposed in the developing tank 131. The developing roller 133 is disposed in the developing tank 131 with a part thereof exposed to the outside.

  The third conveying member 132 rotates and conveys the developer in the developing tank 131 to a position near the developing roller 133 while stirring. The developing roller 133 supplies the developer to the surface of the photoreceptor 41 by rotating. As a result, the electrostatic latent image on the surface of the photoreceptor 41 is visualized by the developer. The developing roller 133 may be referred to as a developing sleeve.

  The development drive unit 134 is a mechanism that rotationally drives the third transport member 132 and the development roller 133. For example, the developing drive unit 134 includes a motor (not shown) and a gear mechanism that transmits the rotational force of the motor to the third transport member 132 and the developing roller 133.

  The first transport member 113, the second transport member 123, and the third transport member 132 are, for example, screw-type transport members having a rotating shaft portion and a spiral blade portion formed around the rotating shaft portion. is there.

  The second passage restriction unit 17 is a mechanism operable in a range from a restricted state in which the passage of the developer is restricted in the second passage 15 to a non-restricted state in which the developer is not restricted. The second passage restriction unit 17 includes a second shielding member 171 and a second shielding member driving unit 172 that are rotatably supported.

  An opening 170 occupying a range equal to or larger than the contour of the cross section of the second passage 15 is formed in a part of the second shielding member 171. The second shielding member driving unit 172 is a mechanism that rotationally drives the second shielding member 171 and holds the first shielding member 161 in a plurality of directions (rotation angles).

  3 to 5 are schematic plan views of a plurality of states of the second passage restriction unit 17. FIG. 3 shows a state where the entire cross section of the second passage 15 is accommodated in the opening 170 of the second shielding member 171. This state is the unrestricted state in which passage of the developer in the second passage 15 is not restricted.

  4 and 5 show a state in which a part of the cross section of the second passage 15 overlaps the second shielding member 171. FIG. These states are the restricted states that restrict the passage of the developer in the second passage 15. FIG. 4 shows a first restriction state in which the degree of restriction of the developer passage in the second passage 15 is relatively small, and FIG. 5 shows that the degree of restriction of the developer passage in the second passage 15 is relatively small. A large second restricted state.

  The second shielding member driving unit 172 positions the second shielding member 171 in a range from the non-restricted state to the second restricted state in accordance with a control signal from the control unit 8.

  The first passage restriction unit 16 is a mechanism operable in a range from the restricted state in which the passage of the developer is restricted in the first passage 14 to the unrestricted state in which the restriction is released. The first passage restriction unit 16 has the same configuration as the second passage restriction unit 17. That is, the first passage restriction unit 16 includes a first shielding member 161 and a first shielding member driving unit 162 that are rotatably supported.

  An opening 160 occupying a range equal to or larger than the contour of the cross section of the first passage 14 is formed in a part of the first shielding member 161. The first shielding member driving unit 162 is a mechanism that rotationally drives the first shielding member 161 and holds the first shielding member 161 in a plurality of directions (rotation angles).

  The first shielding member driving unit 162 positions the first shielding member 161 in a range from the non-restricted state to the second restricted state in accordance with a control signal from the control unit 8.

  The transfer device 45 transfers an image (developer image) on the surface of the photoconductor 41 to the recording sheet 9 that is moving along the conveyance path 30. Finally, the cleaning device 47 removes the developer remaining on the surface of the photoreceptor 41.

  The fixing unit 6 sandwiches the recording sheet 9 on which an image is formed between a fixing roller 61 including a heater 610 such as a halogen heater and a pressure roller 62, and sends the recording sheet 9 to a subsequent process. As a result, the fixing unit 6 heats the image of the developer on the recording sheet 9 and fixes the image on the recording sheet 9.

  The temperature sensor 801 and the humidity sensor 802 are sensors that measure the temperature and humidity of the environment in which the developing device 43 is disposed, respectively. The temperature sensor 801 and the humidity sensor 802 are arranged in the casing 100 or at a position along the casing 100.

  For example, the temperature sensor 801 and the humidity sensor 802 are attached to the position of the control unit 8 or a position around it. It is also conceivable that the temperature sensor 801 and the humidity sensor 802 are arranged at a position closer to the developing device 43.

  The temperature sensor 801 is, for example, a thermistor. The humidity sensor 802 is, for example, a polymer capacitive humidity sensor or a polymer resistance humidity sensor. In addition, a temperature / humidity sensor in which the temperature sensor 801 and the humidity sensor 802 are integrated may be employed.

  The control unit 8 controls various devices included in the image forming apparatus 10. For example, the control unit 8 controls the developer supply driving unit, the intermediate hopper driving unit 124, the first shielding member driving unit 162, and the second shielding member driving unit 172 according to the measurement result of the humidity sensor 802. Control.

  As shown in FIG. 6, the control unit 8 includes an MPU (Micro Processor Unit) 81, a memory 82, a signal interface 83, a drive circuit 84, and the like.

  The MPU 81 is a processor that executes various arithmetic processes. The memory 82 is a nonvolatile storage unit in which information such as control programs Pr1, Pr2, Pr3, Pr4 for causing the MPU 81 to execute various processes is stored in advance. Further, the memory 82 is also a storage unit in which various information can be read and written by the MPU 81.

  The control unit 8 performs overall control of the image forming apparatus 10 by the MPU 81 executing various control programs Pr1, Pr2, and Pr3 stored in the memory 82 in advance.

  The signal interface 83 is an interface circuit that relays signal transfer between the MPU 81 and the sensors and control target devices. The MPU 81 inputs detection signals (measurement signals) from the temperature sensor 801, the humidity sensor 802 and other sensors via the signal interface 83. Further, the MPU 81 outputs a control signal to the drive circuit 84 through the signal interface 83, whereby the developer supply drive unit 114, the intermediate hopper drive unit 124, the development drive unit 134, and the first shielding member. The driving unit 162 and the second shielding member driving unit 172 are controlled.

  The drive circuit 84 drives the developer supply drive unit 114, the intermediate hopper drive unit 124, the development drive unit 134, the first shielding member drive unit 162, and the second shielding member according to a control signal from the MPU 81. This is a circuit that outputs a drive signal to each of the units 172. Each of the developer supply driving unit 114, the intermediate hopper driving unit 124, the development driving unit 134, the first shielding member driving unit 162, and the second shielding member driving unit 172 operates according to the driving signal.

  The developing device 43 according to this embodiment includes a part of the control unit 8 in addition to the developer supply unit 11, the intermediate hopper unit 12, and the developing unit 13. That is, the control unit 8 controls the developer supply driving unit 114, the intermediate hopper driving unit 124, the development driving unit 134, the first shielding member driving unit 162, and the second shielding member driving unit 172. Is a part of the developing device 43 according to the present embodiment.

  By the way, it is known that when the charge amount of the developer is insufficient, development failure is likely to occur. If the operation speed of the third conveying member 132 in the developing tank 131 is increased in order to promote charging of the developer, the developer may be excessively supplied to the developing roller 133. is there. The same applies when the operation speeds of the second stirring member 122 and the second transport member 123 in the intermediate accommodating portion 121 are increased.

  On the other hand, according to the developing device 43 that executes control to be described later, by preventing the developer from being excessively supplied to the developing roller 133, the charging of the developer is promoted according to the environmental change, thereby It is possible to suppress fluctuations in the charge amount of the developer.

[Developer control method]
Next, an example of a method for controlling the developing device 43 will be described with reference to FIGS. FIG. 7 is a flowchart showing an example of a control process of the developing device 43 executed by the control unit 8. The control unit 8 executes the control process shown in FIG. 7 when the image forming unit 4 operates.

  For example, the control unit 8 executes the control process shown in FIG. 7 when an image forming job is generated by the image forming unit 4. In the following description, S1, S2,... Represent processing procedure identification codes. The processing of the control unit 8 shown below is realized by the MPU 81 executing a control program stored in the memory 82.

<Process S1>
First, the control unit 8 inputs measurement results of the temperature sensor 801 and the humidity sensor 802. This step S1 is a step in which the MPU 81 executes the input program Pr1, and is an example of an input step. In the following description, the measurement result of the temperature sensor 801 is referred to as measurement temperature, and the measurement result of the humidity sensor 802 is referred to as measurement humidity.

  Generally, it is known that the developer is more difficult to be charged when the environmental humidity is higher than when the humidity is low. Therefore, the measured humidity is an example of a chargeability parameter that represents the chargeability of the developer. The charging property is a property of being easily charged or difficult to be charged when stirred.

  A typical image forming apparatus often includes the humidity sensor 802. Therefore, when the measurement result of the humidity sensor is used as the chargeability parameter, it is not necessary to add a new sensor for obtaining the chargeability parameter.

<Process S2>
Next, the control unit 8 estimates the chargeability of the developer in the environment where the measurement result is obtained using the measurement result obtained in step S1. This step S2 is a step in which the MPU 81 executes the chargeability estimation program Pr2.

  In step S <b> 2, the control unit 8 estimates that the developer is poorly charged (not easily charged) when the measured humidity (measured value of environmental humidity) is higher than when the measured humidity is low. .

  In general, when the measured humidity (relative humidity) is the same, there is a tendency that the chargeability of the developer is worse (less likely to be charged) when the measured temperature is lower than when the measured temperature is high. Therefore, for example, it is conceivable that the measured humidity is corrected with the measured temperature, and the estimated humidity Hm after correction is used as a parameter used for estimating the chargeability of the developer. In this case, the estimation humidity Hm can be obtained by adding or multiplying the measurement humidity with a coefficient that increases as the measurement temperature decreases.

  FIG. 8 is a diagram illustrating an example of a rule for estimating the chargeability index value Iv of the developer from the estimation humidity Hm. For example, the control unit 8 refers to estimation rule data such as a conversion formula or a look-up table representing the relationship between the estimation humidity Hm and the chargeability index value Iv as shown in FIG. The chargeability index value Iv is estimated. The estimated rule data is recorded in the memory 82 in advance. In the example of FIG. 8, when the chargeability index value Iv is “1”, the chargeability of the developer is in a standard state.

<Process S3>
The control unit 8 controls the first shielding member driving unit 162 and the developer supply driving unit 114 according to the chargeability index value Iv obtained in step S2. Here, the chargeability index value Iv may change from a predetermined state to a state indicating that the chargeability of the developer is worse than that. In that case, the controller 8 causes the first stirring member 112 and the first transport member 113 to operate at a higher speed ratio with respect to the operation speed of the third transport member 132. In parallel with this, the control unit 8 operates the first passage restriction unit 16 from the non-restricted state to the restricted state. This step S3 is an example of a charging promotion control step (charging promotion step) in which the MPU 81 executes the upstream charging promotion control program Pr3.

<Step S4>
Similarly, the control unit 8 controls the second shielding member driving unit 172 and the intermediate hopper driving unit 124 according to the chargeability index value Iv obtained in step S2. Here, the chargeability index value Iv may change from a predetermined state to a state indicating that the chargeability of the developer is worse than that. In this case, the control unit 8 operates the second stirring member 122 and the second transport member 123 at a higher speed ratio with respect to the operation speed of the third transport member 132. In parallel, the control unit 8 operates the second passage restriction unit 17 from the non-restricted state to the restricted state. This step S4 is an example of the charge promotion control step (the charge promotion step) in which the MPU 81 executes the downstream charge promotion control program Pr4.

  FIG. 9 is a diagram illustrating an example of a conveyance operation speed correction rule used by the control unit 8 in steps S3 and S4. For example, the control unit 8 refers to operation speed correction rule data such as a conversion formula or a look-up table representing the relationship between the chargeability index value Iv and the operation speed correction coefficient Rv as shown in FIG. Then, the operation speed correction coefficient Rv is set.

  The operation speed correction coefficient Rv is determined for each of the reference operation speeds of the first stirring member 112 and the first transport member 113 and the reference operation speeds of the second stirring member 122 and the second transport member 123. The correction factor to be applied. The reference operation speed is a speed that forms a predetermined ratio with respect to the operation speed of the third transport member 132. However, the reference operation speeds of the first stirring member 112, the first transport member 113, the second stirring member 122, and the second transport member 123 are not necessarily the same.

  For example, when the control unit 8 operates the developing device 43, the third conveying member 132 and the developing roller 133 in the developing unit 13 are fixed regardless of the chargeability index value Iv (chargeability parameter). Operate at a speed of. In this case, the reference operation speed is a predetermined constant speed.

  In the example shown in FIG. 9, the operation speed correction coefficient Rv is a correction coefficient that is multiplied by the reference operation speed. However, it is also conceivable that the operation speed correction coefficient Rv is a correction coefficient that is added to or subtracted from the reference operation speed.

  In the example shown in FIG. 9, the control unit 8 sets the operation speed correction coefficient Rv to 1 when the chargeability index value Iv is equal to or less than a predetermined reference index value Ivx. Further, the control unit 8 sets the operation speed correction coefficient Rv to a value larger than 1 when the chargeability index value Iv exceeds the reference index value Ivx. Further, the control unit 8 sets the operation speed correction coefficient Rv to a larger value as the chargeability index value Iv becomes larger than the reference index value Ivx.

  Then, the control unit 8 corrects the driving speeds of the developer supply driving unit 114 and the intermediate hopper driving unit 124 in accordance with the operation speed correction coefficient Rv. More specifically, the control unit 8 corrects the first stirring member 112 and the first transport member 113 obtained by applying the operation speed correction coefficient Rv to the reference operation speed for them. Operate at a later speed.

  FIG. 10 is a diagram showing an example of a developer passage restriction rule used by the control unit 8 in steps S3 and S4. For example, the control unit 8 refers to passage restriction rule data such as a conversion formula or a lookup table representing the relationship between the chargeability index value Iv and the passage opening coefficient Ro as shown in FIG. A passage opening coefficient Ro is set.

  The passage opening coefficient Ro corresponds to the opening ratio of each of the first passage 14 and the second passage 15. The passage opening coefficient Ro being “1” means that the opening ratio of each of the first passage 14 and the second passage 15 is 100%. That is, when the passage opening coefficient Ro is set to “1”, the control unit 8 does not restrict the passage of the developer to each of the first passage restriction unit 16 and the second passage restriction unit 17. The unrestricted state is adjusted (see FIG. 3).

  On the other hand, when the passage opening coefficient Ro is set to a value smaller than “1”, the control unit 8 passes the developer through each of the first passage restriction unit 16 and the second passage restriction unit 17. Is adjusted to the restricted state (see FIGS. 4 and 5). However, the passage opening coefficient Ro for the first passage restriction portion 16 and the passage opening coefficient Ro for the second passage restriction portion 17 are not necessarily the same.

  In the example shown in FIG. 10, the passage opening coefficient Ro corresponds to the opening ratio of the developer passage, but the passage opening coefficient Ro is added to or subtracted from a predetermined reference opening ratio. It is also conceivable that the correction coefficient is set.

  In the example shown in FIG. 10, the control unit 8 sets the passage opening coefficient Ro to 1 when the chargeability index value Iv is equal to or less than the predetermined reference index value Ivx. Further, the control unit 8 sets the passage opening coefficient Ro to a value smaller than 1 when the charging index value Iv exceeds the reference index value Ivx. Further, the controller 8 sets the passage opening coefficient Ro to a smaller value as the charging index value Iv becomes larger than the reference index value Ivx.

  Then, the control unit 8 adjusts the first shielding member driving unit 162 and the second shielding member driving unit 172 according to the passage opening coefficient Ro. More specifically, the control unit 8 includes the first shielding member 161 and the second shielding member 161 so that each of the first passage 14 and the second passage 15 opens with an opening ratio corresponding to the passage opening coefficient Ro. The direction (rotation angle) of the second shielding member 171 is set.

  That is, in step S3, when the measured humidity (chargeability parameter) is changed from a predetermined state to a state indicating that the chargeability is worse than that, the first stirring member 112 is controlled. In addition, the first transport member 113 is operated at a higher speed ratio than the operation speed of the third transport member 132, and the first passage restriction unit 16 is operated from the unrestricted state to the restricted state.

  Similarly, in Step S4, when the measured humidity (chargeability parameter) changes from a predetermined state to a state indicating that the chargeability is worse than that, the second stirring member 122 and the second transport member 123 are operated at a higher speed ratio than the operation speed of the third transport member 132, and the second passage restriction unit 17 is operated from the unrestricted state to the restricted state. Steps S3 and S4 are an example of a charging promotion step.

  As described above, in an environment where the chargeability of the developer is deteriorated, the operation speed of the second stirring member 122 and the second transport member 123 in the intermediate accommodating portion 121 is increased (S4). . Thereby, charging of the developer is promoted, and the charge amount of the developer is appropriately maintained. As a result, poor development due to insufficient charging of the developer is prevented.

  In the present embodiment, the operating speed of the first stirring member 112 and the first transport member 113 in the developer container 111 is also increased in an environment where the chargeability of the developer deteriorates (S3). . Thereby, charging of the developer is further promoted, and the charge amount of the developer is more reliably maintained in an appropriate state.

  Further, when the operation speeds of the second stirring member 122 and the second transport member 123 are increased, the second passage restriction unit 17 restricts the passage of the developer in the second passage 15. This prevents the developer from being excessively supplied to the developing roller 133.

  Similarly, when the operating speed of the first stirring member 112 and the first transport member 113 is increased, the first passage restriction unit 16 restricts the passage of the developer in the first passage 14. As a result, it is possible to prevent the supply speed of the developer into the intermediate accommodating portion 121 from fluctuating in accordance with the change in the operation speed of the first transport member 113, and consequently the developer to the developing roller 133. It is possible to prevent the supply speed from fluctuating.

[Other application examples]
According to the example shown in FIG. 9, when the chargeability index value Iv exceeds the reference index value Ivx, the operating speeds of the first transport member 113 and the second transport member 123 are the chargeability index value. It is continuously changed according to the change of Iv. However, it is also conceivable that the operation speeds of the first transport member 113 and the second transport member 123 are changed stepwise in two steps or three or more steps according to the chargeability index value Iv.

  Further, according to the example shown in FIG. 10, when the chargeability index value Iv exceeds the reference index value Ivx, the degree of restriction on the passage of the developer in the first passage 14 and the second passage 15 ( The opening ratio of the passage is continuously changed according to the change of the chargeability index value Iv. However, it is also conceivable that the degree of restriction of the developer passage in the first passage 14 and the second passage 15 is changed stepwise in two steps or three or more steps according to the chargeability index value Iv. .

  In the control of the developing device 43, the measured humidity may be used as it is as the charging index value Iv. It is also conceivable that parameters other than the measured humidity are used as the chargeability parameter representing the chargeability of the developer.

  For example, the image forming unit 4 includes an image density sensor that measures the density of an image (developer image) on the photoconductor 41, and the image forming unit 4 performs a predetermined test on the photoconductor 41. It is conceivable to develop the image. In this case, it is considered that the density of the test image measured by the image density sensor is used as the chargeability parameter. A low density of the test image indicates that the developer is poorly charged.

  For example, it is conceivable that the test image is formed in an area outside the passing area of the recording sheet 9 on the surface of the photoreceptor 41. It is also conceivable that the development of the test image is performed at a timing different from the timing of image formation on the recording sheet 9.

  The density of the test image is a parameter that directly indicates a situation in which a deterioration in the charging property of the developer appears as a development failure. If the charge acceleration control is performed based on such parameters, it is possible to prevent development defects more reliably.

  The developing device, the image forming apparatus, and the developing device control method according to the present invention can be freely combined or implemented within the scope of the invention described in each claim. It is also possible to configure by modifying the form and application examples as appropriate or omitting some of them.

2: Sheet feeding unit 3: Sheet conveying unit 4: Image forming unit 5: Optical scanning unit 6: Fixing unit 8: Control unit 9: Recording sheet 10: Image forming apparatus 11: Developer supplying unit 12: Intermediate hopper unit 13: Developing unit 14: First passage 15: Second passage 16: First passage restriction unit 17: Second passage restriction unit 21: Sheet receiving unit 22: Sheet feeding unit 30: Conveying path 31: Conveying roller 41: Photoconductor (image) Carrier)
42: charging device 43: developing device 45: transfer device 47: cleaning device 61: fixing roller 62: pressure roller 81: MPU
82: Memory 83: Signal interface 84: Drive circuit 100: Housing 101: Discharge tray 110: First storage space 111: Developer container 112: First stirring member 113: First transport member 114: Developer supply driving unit 120 : Second accommodating space 121: intermediate accommodating portion 122: second agitating member 123: second conveying member 124: intermediate hopper drive unit 130: third accommodating space 131: developing tank 132: third conveying member 133: developing roller 134: Development drive unit 140: first supply unit 150: second supply unit 160: opening 161: first shielding member 162: first shielding member driving unit 170: opening 171: second shielding member 172: second shielding member driving unit 610: heater 801: temperature sensor 802: humidity sensor 1111: first discharge port 1210: first supply port 1211 : Second discharge port 1310: second supply port Pr1: input program Pr2: chargeability estimation program Pr3: upstream charging promotion control program Pr4: downstream charging promotion control program

Claims (6)

A developer container that contains a developer, and a developer supply section that has a first transport member that transports the developer to the first passage while stirring the developer in the developer container;
An intermediate storage portion for temporarily storing the developer supplied by dropping the first passage from the developer supply portion, and a second transport member for transporting the developer to the second passage while stirring the developer in the intermediate storage portion An intermediate hopper having
A developing tank for temporarily storing the developer supplied by dropping the second passage from the intermediate hopper, a developing roller for supplying the developer in the developing tank to an image carrier, and the developing tank in the developing tank A developing unit having a third conveying member that conveys the developer to the developing roller while stirring;
A second passage restriction portion operable in a range from a restricted state that restricts passage of the developer in the second passage to an unrestricted state that does not restrict the developer;
When the chargeability parameter representing the chargeability of the developer changes from a predetermined state to a state indicating that the developer is less likely to be charged, the second transport member is moved to the third transport member. And a control unit capable of performing charging promotion control that causes the second passage restriction unit to operate from the non-restricted state to the restricted state while operating at a higher speed ratio than the operation speed. A first passage restriction unit operable in a range from the restricted state to the unrestricted state in the first passage;
In the charge acceleration control, when the chargeability parameter is changed from a predetermined state to a state indicating that the developer is less likely to be charged, an operation speed of the third transport member is changed. The developing device according to claim 1, further comprising a control for operating the first passage restriction unit from the unrestricted state to the restricted state while operating at a faster speed ratio.   The chargeability parameter includes a measured value of environmental humidity, and indicates that the developer is less likely to be charged when the measured value of the environmental humidity is higher than when the measured value of the environmental humidity is low. Item 3. The developing device according to Item 2.   The developing device according to claim 1, wherein an operation speed of the third transport member is constant regardless of the charging parameter. A developing device according to any one of claims 1 to 4,
And an image carrier to which the developer is supplied from the developing device. A developer container that contains a developer, and a developer supply section that has a first transport member that transports the developer to the first passage while stirring the developer in the developer container;
An intermediate storage portion for temporarily storing the developer supplied by dropping the first passage from the developer supply portion, and a second transport member for transporting the developer to the second passage while stirring the developer in the intermediate storage portion An intermediate hopper having
A developing tank for temporarily storing the developer supplied by dropping the second passage from the intermediate hopper, a developing roller for supplying the developer in the developing tank to an image carrier, and the developing tank in the developing tank A developing unit having a third conveying member that conveys the developer to the developing roller while stirring;
A developing device control method comprising: a second passage restriction portion operable in a range from a restricted state that restricts passage of the developer in the second passage to an unrestricted state that does not restrict the developer,
An input step for inputting a chargeability parameter representing the chargeability of the developer;
When the charging property parameter changes from a predetermined state to a state indicating that the developer is less likely to be charged, the second transport member is faster than the operating speed of the third transport member. And a charging promotion step of operating the second passage restriction portion from the non-restricted state to the restricted state while operating at a ratio.

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