JP2018136398A - Image forming apparatus and developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently stabilize the amount of charging of developer.SOLUTION: An image forming apparatus comprises: a developing device 10 that supplies a developer containing toner to a developing area where a toner image is formed; and a control part. The developing device 10 includes a plurality of conveying members 31, 32 that convey, while stirring, the developer in a predetermined direction along a circulation path. The control part controls the operations of the conveying members 31, 32 such that a difference occurs in conveyance speed of the developer conveyed respectively by adjacent two conveying members 31, 32 in the circulation path.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus suitable for controlling a developing device that supplies a developer containing toner to a developing region where a toner image is formed, and the developing device.

  Conventionally, in a developing device of an image forming apparatus such as an MFP (Multi-Functional Peripheral), a printer, and a facsimile, a two-component developer including toner and a magnetic carrier is sometimes used. In such a two-component developer, when the charge amount becomes unstable, the print quality is deteriorated or the toner is scattered from the developing device.

  The charge amount of the developer is stabilized by increasing the collision energy between the toner and the magnetic carrier. The collision energy can be adjusted by the stirring energy for stirring the developer. The stirring energy varies depending on the stirring time, the stirring speed, and the stirring torque.

  For example, in a developing device, depending on at least one of a cumulative rotation time of a developing roller (hereinafter also referred to as “developer carrier”) and a standing time from a previous image formation request, a stirring blade (hereinafter referred to as “conveying member”). (Also referred to as Patent Document 1).

JP 2010-156911 A

  However, in the conventional technique, most of the stirring energy due to the increase in at least one of the stirring time and the stirring speed is consumed as transport energy for circulating the developer in the developing device. For this reason, it is conceivable to stabilize the charge amount of the developer more efficiently by increasing the stirring energy.

  The present invention has been made to solve the above-described problems, and one of the objects of the present invention is to provide an image forming apparatus and a developing apparatus capable of efficiently stabilizing the charge amount of the developer. It is.

  In order to achieve the above object, according to one aspect of the present invention, an image forming apparatus includes a developing device that supplies a developer containing toner to a developing region where a toner image is formed, and a control unit. . The developing device includes a plurality of transport members that stir while transporting the developer in a predetermined direction along the circulation path. The control unit controls the operation of the transport member so that a difference occurs in the transport speed of the developer transported by each of the two transport members adjacent in the circulation path.

  Preferably, the conveying member is agitated while being conveyed in the direction of the rotation axis by being rotated. The control unit controls the rotation speed of the transport member so that a difference occurs in the transport speed of the developer transported by each of the two transport members adjacent in the circulation path.

  More preferably, as long as each conveying member has the same rotation speed, the developer can be conveyed at a similar conveying speed. The control unit controls the rotation speed of the conveyance member so that a difference occurs between the rotation speeds of two conveyance members adjacent in the circulation path.

  Preferably, the control unit controls the transport speed of the transport member so that the transport speed of the first transport member is faster than the transport speed of the second transport member farther from the development region than the first transport member.

  Preferably, before the developer is supplied to the development area, the control unit determines the difference in transport speed between the two transport members adjacent to each other in the circulation path according to the time during which the developer is left without stirring. Change.

  Preferably, the control unit periodically changes a difference in conveyance speed between two conveyance members adjacent in the circulation path.

  Preferably, the apparatus further includes a detection unit that detects torque for operating any one of the conveying members. The control unit changes the difference between the conveyance speeds of the two conveyance members adjacent in the circulation path according to the torque detected by the detection unit.

  Preferably, before supplying the developer to the development area, the control unit conveys the developer so that the amount of the developer near the development area in the circulation path is smaller than when the developer is supplied to the development area. To control the transport speed.

  Preferably, the developing device further includes a supply member that supplies a developer to the developing region. The plurality of conveyance members are provided in a second circulation path that communicates with a first conveyance member provided in the first circulation path along the supply member in the circulation path and a downstream communication portion with respect to a predetermined direction of the first circulation path. Second conveying member. The developing device further includes a retention portion that retains the developer in the communication portion.

  According to another aspect of the present invention, the developing device is a developing device that supplies a developer containing toner to a developing region where a toner image is formed. The developing device includes a plurality of transport members that stir while transporting the developer in a predetermined direction along the circulation path. Each transport member is operable so that a difference occurs in the transport speed of the developer transported by each of the two transport members adjacent in the circulation path.

  According to the present invention, it is possible to provide an image forming apparatus and a developing apparatus capable of efficiently stabilizing the charge amount of the developer.

1 is a block diagram illustrating an outline of a configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a diagram illustrating a main part of an image forming apparatus according to an embodiment. It is a figure which shows the outline of a structure of the developing device in this Embodiment. It is a figure which shows the change of the rotational speed ratio of the conveyance member of the developing device in 3rd Embodiment. It is a figure which shows the outline of a structure of the developing device in 4th Embodiment. It is a figure which shows the outline of a structure of the developing device in 5th Embodiment. It is a figure which shows the liquid level of the developer of the developing device in 5th Embodiment.

  Embodiments of the present invention will be described in detail with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a block diagram showing an outline of the configuration of an image forming apparatus 100 according to an embodiment of the present invention. Referring to FIG. 1, image forming apparatus 100 controls controller 210 for controlling the entire image forming apparatus 100, storage unit 220 for storing predetermined information, and image forming apparatus 100. An operation unit 230, a display unit 240 for displaying predetermined information of the image forming apparatus 100, a communication unit 260 for communicating with an external apparatus via the private network 900, and a scanner for reading a predetermined image. A unit 270 and a printer unit 280 for printing a predetermined image.

  The storage unit 220 includes a RAM (Random Access Memory) used as a work area necessary for executing a program by the control unit 210 and a ROM (Read Only Memory) for storing a program to be executed by the control unit 210. Including. In addition, a program and data for executing a predetermined process are read and stored in the RAM from the operation unit 230, the communication unit 260, or the scanner unit 270. Furthermore, a hard disk drive or a memory card may be used as an auxiliary storage device for assisting the storage area of the RAM.

  The operation unit 230 includes a plurality of operation buttons for causing the image forming apparatus 100 to execute a predetermined function, and a touch panel configured on a display of the display unit 240. An operation signal indicating the operation content input to the image forming apparatus 100 by operating the operation button and the touch panel of the operation unit 230 is transferred to the control unit 210.

  The display unit 240 includes a liquid crystal display device (hereinafter referred to as “LCD”) having a touch panel as a display. The LCD of the display unit 240 displays an image received from the control unit 210 and indicating the state of the image forming apparatus 100 and the operation buttons of the touch panel. The display unit 240 may include another flat panel display (FPD) such as an EL (Electro-Luminescence) display, a plasma display, or an SED (Surface-conduction Electron-emitter Display) instead of the LCD.

  The communication unit 260 transmits / receives data to / from an external device through the private network 900 using a predetermined protocol. The communication unit 260 transmits data received from the control unit 210 to the outside, and transfers data received from the outside to the control unit 210.

  The scanner unit 270 optically reads visible information on the surface of paper or other objects, converts the read image into image data, and passes the image data to the control unit 210.

  The printer unit 280 converts the image data received from the control unit 210 into an image, and prints the image on printing paper.

  The control unit 210 includes an MPU (Micro Processing Unit) and its auxiliary circuit. The control unit 210 controls the storage unit 220, the operation unit 230, the display unit 240, the communication unit 260, the scanner unit 270, and the printer unit 280, and executes predetermined processing according to programs and data stored in the storage unit 220. The data input from the operation unit 230, the communication unit 260, or the scanner unit 270 is processed, and the processed data is stored in the storage unit 220, displayed on the display unit 240, or output from the communication unit 260. The printer unit 280 performs printing.

  The copy function, printer function, scanner function, facsimile function and communication function of the image forming apparatus 100 are respectively the control unit 210, storage unit 220, operation unit 230, display unit 240, communication unit 260, scanner unit 270 and printer unit 280. This is realized by the cooperation of each unit of the image forming apparatus 100.

  FIG. 2 is a diagram showing a main part of the image forming apparatus 100 in this embodiment. Referring to FIG. 2, an image forming apparatus 100 is an apparatus that forms an image by transferring a toner image formed on an image carrier (photoconductor) 51 to a transfer medium 110 such as a sheet by an electrophotographic method.

  The printer unit 280 of the image forming apparatus 100 includes an image carrier 51, a charging member 53, an exposure device 56, a developing device 10, a transfer roller 54, and a cleaning blade 55.

  The image carrier 51 carries an image. The image carrier 51 is provided to be rotatable in the direction indicated by the arrow A. The charging member 53, the exposure device 56, the developing device 10, the transfer roller 54, and the cleaning blade 55 are provided side by side in the rotation direction of the image carrier 51 in the order listed here.

  The charging member 53 is provided as a charging unit for charging the image carrier 51. The exposure device 56 irradiates the image carrier 51 with light, thereby lowering the charge level in the irradiated region and forming an electrostatic latent image. The developing device 10 develops the electrostatic latent image on the image carrier 51. That is, the developing device 10 supplies a developer to the image carrier 51 and forms a toner image by attaching the toner contained in the developer to the electrostatic latent image. The transfer roller 54 transfers the toner image on the image carrier 51 to the transfer medium 110. The cleaning blade 55 is provided as a means for removing residual toner on the image carrier 51.

  The flow of image formation in the image forming apparatus 100 will be described. First, the image carrier 51 is charged by the charging member 53. Next, an electrostatic latent image is formed on the surface of the image carrier 51 by being exposed by an exposure device 56 equipped with a laser emitter or the like at the position of point E in the drawing. The developing device 10 develops the electrostatic latent image into a toner image. The transfer roller 54 transfers the toner image on the image carrier 51 to the transfer medium 110, and then discharges the transfer medium 110 in the direction indicated by the arrow C in the drawing. The cleaning blade 55 removes the residual toner on the image carrier 51 after the transfer with a mechanical force.

  A known electrophotographic technique may be arbitrarily used as the image carrier 51, the charging member 53, the exposure device 56, the transfer roller 54, the cleaning blade 55, and the like used in the image forming apparatus 100. For example, although a charging roller is shown as the charging member 53 in FIG. 1, a charging device that is not in contact with the image carrier 51 may be used. For example, the cleaning blade 55 may not be used.

  Next, the structure of the developing device 10 will be described. The developing device 10 includes a casing 20, a developer carrier 11, a regulating member 16, a conveyance member (developer carrier side) 31, a conveyance member (toner supply side) 32, and a toner supply unit 15.

  The developer carrier 11 carries and conveys the developer 23 stored in the developer tank 17 on the surface thereof. The developer carrier 11 has a magnet roller 25 and a sleeve roller 26. The magnet roller 25 is fixed. The sleeve roller 26 is provided so as to contain the magnet roller 25. The sleeve roller 26 is provided to be rotatable in the direction indicated by the arrow B. At the time of image formation, a bias for developing toner from the developer carrier 11 to the image carrier 51 is applied to the developer carrier 11.

  The regulating member 16 is disposed with a gap from the outer peripheral surface of the developer carrier 11 (sleeve roller 26). The regulating member 16 is for developer thinning, and regulates the amount of developer on the developer carrier 11. As a result, a part of the developer 23 conveyed by the developer carrier 11 is returned to the developer recovery region 13.

  The casing 20 forms a developer tank 17. A developer 23 is stored in the developer tank 17. The conveyance member 31 and the conveyance member 32 are accommodated in the casing 20. The conveying member 31 and the conveying member 32 circulate and convey the developer carrier 11 in the developer tank 17 while mixing and stirring the developer 23. The conveyance member 31 is disposed to face the developer carrier 11. The developer 23 is supplied to the developer carrier 11 while being transported by the transport member 31.

  Preferably, an ATDC (Automatic Toner Density Control) sensor 21 for toner density detection is provided at a position facing the conveying member 32.

  The toner replenishing unit 15 replenishes the developer tank 17 with the amount of toner consumed by the supply from the developer carrier 11 to the image carrier 51. The conveying member 32 is disposed to face the toner replenishing unit 15. The toner replenishing unit 15 replenishes the replenishment toner 22 into the developer tank 17 from above the conveyance member 32.

  The toner supply unit 15 includes a hopper 15 h that stores the supply toner 22. The casing 20 is provided with a toner supply port 15i. The toner replenishing port 15 i is opened above the conveying member 32. The replenishing toner 22 sent from the hopper 15h is replenished into the developer tank 17 through the toner replenishing port 15i.

  The developer 23 is a developer (two-component developer) containing toner and a carrier for charging the toner.

  The toner is not particularly limited, and a commonly known toner can be used. As the toner, it is possible to use a binder resin containing a colorant, and if necessary, a charge control agent or a release agent, and further processed with an external additive. The toner particle size is not particularly limited, but is preferably about 3 to 15 μm.

  The carrier is not particularly limited, and a known carrier that is generally used can be used. For example, a binder-type carrier or a coat-type carrier can be used. The particle size of the carrier is not particularly limited, but is preferably 15 to 100 μm.

  The binder type carrier is obtained by dispersing magnetic fine particles in a binder resin, and positive or negative chargeable fine particles can be fixed to the carrier surface or a surface coating layer can be provided. Charging characteristics such as polarity of the binder type carrier can be controlled by the material of the binder resin, the chargeable fine particles, and the type of the surface coating layer.

  The mixing ratio of the toner and the carrier may be adjusted so as to obtain a desired toner charge amount. The toner ratio is preferably 3 to 50% by weight, more preferably 6 to 30% by weight, based on the total amount of toner and carrier.

  Here, the operation of the developing device 10 will be described. The developer 23 in the developer tank 17 is mixed and stirred by the transport member 31 and the transport member 32 so as to be frictionally charged and simultaneously circulated and transported in the developer tank 17. During this time, the developer 23 is supplied from the conveying member 31 to the sleeve roller 26 on the surface of the developer carrier 11. The developer 23 is held on the surface side of the sleeve roller 26 by the magnetic force of the magnet roller 25 inside the developer carrier 11 and rotates together with the sleeve roller 26. The developer 23 held by the sleeve roller 26 is restricted in its passing amount by a regulating member 16 provided facing the developer carrier 11. The developer carrier 11 is applied with a DC voltage alone or a bias in which an AC voltage is superimposed on the DC voltage, and the toner is developed from the developer carrier 11 to the image carrier 51 in the development region 62.

  The developer 23 that has passed through the development region 62 is conveyed toward the developer tank 17 as the sleeve roller 26 rotates. The developer 23 is peeled from the developer carrier 11 by the repulsive magnetic field generated by the magnet roller 25 in the developer recovery area 13 and recovered into the developer tank 17. When a supply control unit (not shown) provided in the toner supply unit 15 detects from the output value of the ATDC sensor 21 that the toner concentration in the developer 23 has become equal to or lower than the minimum toner concentration for ensuring image density, The replenishing toner 22 stored in the hopper 15h is supplied into the developer tank 17 through the toner replenishing port 15i.

  The conveying member 32 is composed of a screw. More specifically, the conveying member has a shaft portion and a blade portion. The shaft portion has a shaft shape extending along the central axis. The shaft portion is provided so as to be rotatable about the central axis. That is, the central axis is the rotational central axis of the shaft portion.

  The blade portion extends in the radial direction from the shaft portion, and is provided in a spiral shape along the axial direction of the shaft portion. When the shaft portion rotates, the blade portion is integrated with the shaft portion and rotates around the central axis. Thereby, the developer 23 in the casing 20 is conveyed by receiving the driving force from the blade portion. The transport member 31 has the same screw structure as that of the transport member 32.

  FIG. 3 is a diagram showing an outline of the configuration of the developing device 10 in this embodiment. With reference to FIG. 3, the conveying member 31 is arranged in parallel with the conveying member 32. The transport path 74 of the developer 23 by the transport member 31 and the transport path 75 of the developer 23 by the transport member 32 are connected at both ends of the transport paths 74 and 75. The developer 23 receives a driving force as the conveying members 31 and 32 rotate, and is conveyed in the directions of the arrows indicating the conveying paths 74 and 75 in FIG. 3, respectively. That is, the conveyance paths 74 and 75 constitute a circulation path for the developer 23 that is conveyed in the direction of the arrow.

[First Embodiment]
In the above configuration, if the rotation speeds of the conveyance members 31 and 32 are the same, the conveyance speeds of the developer 23 in the conveyance paths 74 and 75 are conveyed at the same rotation speed when the conveyance speeds of the developer 23 are the same. When the members 31 and 32 are driven, the transport speeds of the developer 23 in the transport paths 74 and 75 are approximately the same. In such a case, most of the stirring energy given to the developer 23 by the transport members 31 and 32 is consumed as transport energy for circulating the developer 23 in the casing 20 of the developing device 10. For this reason, it is conceivable to stabilize the charge amount of the developer 23 more efficiently by increasing the stirring energy.

  Therefore, in the first embodiment, when the developing device 10 includes a plurality of transport members 31 and 32 that stir while transporting the developer 23 in a predetermined direction along the circulation path including the transport paths 74 and 75. The control unit 210 controls the operations of the transport members 31 and 32 so that a difference occurs in the transport speed of the developer 23 transported by each of the two transport members 31 and 32 adjacent in the circulation path. As a result, shearing between the particles of the developer 23 occurs, the conveyance torque increases, and energy given to the developer 23 is consumed not only for conveyance but also for stirring. As a result, since the collision energy and the contact probability between the carrier of the developer 23 and the toner increase, the charge amount of the developer 23 can be stabilized efficiently.

  The conveyance speed of the developer 23 is determined by the conveyance capability, the rotation speed, the cross-sectional shape of the conveyance path, and the like. In this embodiment, it is assumed that the cross-sectional shapes of the conveyance paths 74 and 75 on the plane perpendicular to the rotation center axis of the conveyance members 31 and 32 are substantially the same. In addition, it is assumed that the conveyance capabilities of the conveyance members 31 and 32 are substantially the same. That is, in this embodiment, the conveyance speed of the developer 23 in the conveyance paths 74 and 75 is substantially the same if the rotation speeds of the conveyance members 31 and 32 are the same.

  The motor 71 is controlled by the control unit 210 to rotate the transport member 31. The motor 72 is controlled by the control unit 210 to rotate the transport member 32. And the control part 210 controls the motors 71 and 72 so that the rotational speed of the conveyance members 31 and 32 may differ.

  Table 1 shows data of examples and comparative examples when the rotation speeds of the conveying members 31 and 32 are controlled to be different.

  Referring to Table 1, these values are obtained by using a developer 23 having a usage history of about 2 hours, and the coverage (printing rate), which is the ratio of printed portions per unit area, is 10 to 30%. This is the value when development is performed for a minute.

  The rotation speed ratio of the conveying members 31 and 32 is n1: n2. The agitation energy per unit mass given to the developer 23 is changed from the energy per unit mass given to the conveyance member from the motor to the conveyance energy consumed for the movement of the developer 23 per unit mass and heat. Calculated by subtracting other energy consumed. However, here, assuming that the conveyance energy and other energy are approximated to zero, the stirring energy per unit mass given to the developer 23 is equal to the energy per unit mass given from the motor to the conveyance member. .

  The charge stability rate of the developer 23 is calculated by dividing the increased charge amount by the target charge amount, assuming that it is a coincidence rate with the target charge rate. The scattering amount of the developer 23 was obtained by measuring an integrated value per minute of the number of particles of 5 μm or more in 1 L of air using a particle counter (manufactured by Rion Co., Ltd., model: KR-11B).

  As Comparative Example 1, when the rotation speed ratio is n1: n2 = 1.0: 1.0, the stirring energy ratio given to the developer 23 based on the value in Example 1-1 is 0.1, and the charging stability ratio is 80%, and the amount of scattering is 360 / L.

  In contrast, in Example 1-1, when the rotation speed ratio is n1: n2 = 1.0: 0.8, the charging stability is 97% and the scattering amount is 250 / L.

  Further, as Example 1-2, when the rotation speed ratio n1: n2 = 0.8: 1.0, the stirring energy ratio given to the developer 23 based on the value in Example 1-1 is 1.0. The charging stability rate is 97%, and the amount of scattering is 270 / L.

  Thus, like Example 1-1 and Example 1-2, when the difference of the rotational speed of the conveyance members 31 and 32 is attached, the case of the comparative example 1 which does not attach the difference of rotational speed is added. In comparison, more agitation energy can be applied to the developer 23. As a result, the charging stability rate of the developer 23 increases and the amount of scattering of the developer 23 decreases.

  Further, as in Example 1-2, when the rotation speed of the conveying member 31 on the side close to the developer carrier 11 is made slower than in the case of Example 1-1, the developer carrier 11 is in contact. The amount of the developer 23 in the transport path 74 is increased. As a result, the amount of the developer 23 supplied to the developer carrier 11 is increased, so the amount of the developer 23 returned to the developer recovery region 13 is increased, and the developer recovery region 13 is easily clogged. As a result, the flow of the developer 23 passing through the regulating member 16 becomes unstable, so that excessive stress is applied to the developer 23 or the developer 23 is likely to be scattered.

  When the printing is not being performed, the developer carrier 11 may be stopped so that the developer 23 is not exposed to the outside of the developing device 10.

[Second Embodiment]
In the second embodiment, the control unit 210 changes the difference in transport speed according to the time during which the developer 23 is left without stirring. Table 2 shows data of Examples and Comparative Examples for each developer 23 leaving time.

  Referring to Table 2, these values are obtained using the developer 23 left at high temperature (30 ° C.) and high humidity (80%) during the storage time shown in Table 2, respectively. Similarly, the coverage (printing rate), which is the ratio of the printed portion per unit area, is 10 to 30%, and is a value when development is performed for 1 minute.

  As Example 2, when the charge amount after storage is 0.96 (fc / μm) at a storage time of 100 hours, and the rotation speed ratio is n1: n2 = 1.0: 1.0, the storage time of Example 2 is 200 hours. The stirring energy ratio given to the developer 23 based on the value is 0.1, and the charging stability rate is 97%.

  When the storage amount is 150 hours and the charge amount after storage is 0.91 (fc / μm), the rotation speed ratio is n1: n2 = 1.0: 0.9, and the value when the storage time is 200 hours in Example 2 is used as a reference. The stirring energy ratio given to the developer 23 is 0.5, and the charging stability is 97%.

  When the charge amount after storage is 0.86 (fc / μm) with a storage time of 200 hours, the charge stability ratio is 97% when the rotation speed ratio is n1: n2 = 1.0: 0.8.

  As Comparative Example 2, when the charge amount after storage is 0.96 (fc / μm) at a storage time of 100 hours, the rotation speed ratio is n1: n2 = 1.0: 1.0, and the storage time of Example 2 is 200 hours. The stirring energy ratio given to the developer 23 based on the value is 0.1, and the charging stability rate is 97%.

  When the storage amount is 150 hours and the charge amount after storage is 0.91 (fc / μm), the rotation speed ratio is n1: n2 = 1.0: 1.0, and the value when the storage time is 200 hours in Example 2 is used as a reference. The stirring energy ratio given to the developer 23 is 0.1, and the charging stability rate is 92%.

  When the charge amount after storage is 0.86 (fc / μm) at a storage time of 200 hours, the rotation speed ratio is n1: n2 = 1.0: 1.0, and the value at the storage time of 200 hours in Example 2 is used as a reference. The stirring energy ratio applied to the developer 23 is 0.1, and the charging stability ratio is 87%.

  Thus, the longer the storage time, the greater the difference in rotational speed as in Example 2, as compared to the case in which no difference in rotational speed is provided, as in Comparative Example 2. Agitation energy can be applied to the developer 23, and as a result, the charging stability rate of the developer 23 increases. Further, if the minimum required stirring energy is given to the developer 23 according to the storage time, efficient control can be performed. As in the first embodiment, the higher the charging stability rate, the smaller the scattering amount of the developer 23.

[Third Embodiment]
In the third embodiment, the control unit 210 periodically changes the difference in the conveyance speed. FIG. 4 is a diagram illustrating a change in the rotational speed ratio of the conveying members 31 and 32 of the developing device 10 according to the third embodiment. Referring to FIG. 4, in this embodiment, control unit 210 has a rotation speed ratio of conveyance member 31 when the rotation speed of conveyance member 32 is 0.9. ), The difference in the rotational speeds of the conveying members 31 and 32 is periodically changed so as to change in a pulse shape. Table 3 shows data of examples and comparative examples when the difference in the conveyance speed of the developer 23 is periodically changed.

  Referring to Table 3, these values indicate that the fluidity of the developer 23 deteriorates due to an error (the life of the developer 23, the environment, the toner concentration, etc.) that changes the fluidity of the developer 23, and the difference in conveyance speed. As shown in Table 1, the coverage (printing rate), which is the ratio of the printed portion per unit area, is 10 to 30%, and is the value when development is performed for 1 minute. is there.

  As Comparative Example 3, the rotation speed ratio n1: n2 = 1.0: 0.8 and no period change. Thus, as in Comparative Example 3, when the rotational speed ratio is in a state with a constant difference, the flow of the developer 23 deteriorates due to an error, and development in a state where clogging due to a difference in transport speed is likely to occur. When the agent 23 is used, a state in which the liquid level of the developer 23 in the conveyance path 74 in contact with the developer carrying member 11 becomes relatively high becomes remarkable. Here, the developer 23 is powder, not liquid, but the upper surface of the developer 23 in the conveyance path 74 is conventionally called the liquid level.

  On the other hand, as Example 3, the rotational speed ratio n1: n2 = 1.0 to 0.8: 0.9, and the cycle of the rotational speed n1 is 2.0 Hz. As described above, the third embodiment includes a case where the magnitude relationship between the rotational speeds of the transport members 31 and 32 is reversed or equal. Further, the time average of the rotation speed of the transport member 31 is made equal to the rotation speed of the transport member 32. As a result, the liquid level of the developer 23 in the conveyance path 74 in contact with the developer carrier 11 becomes lower than that in the case of Comparative Example 3. Thus, in the case of Example 3, the clogging of the developer 23 can be reduced as compared with the case of Comparative Example 3.

  In Example 3, the rotation speed of the conveyance member 32 far from the developer carrier 11 is kept constant, and the rotation speed of the conveyance member 31 closer to the developer carrier 11 is changed. However, the present invention is not limited to this, and conversely, the rotational speed of the transport member 31 closer to the developer carrier 11 is made constant, and the rotational speed of the transport member 32 far from the developer carrier 11 is changed. May be.

[Fourth Embodiment]
In the fourth embodiment, a torque sensor 73 that detects torque for operating one of the conveying members 31 and 32 is further provided, and the control unit 210 is adjacent to the two conveying members 31 and 32 in the circulation path. The difference in the respective transport speeds is changed according to the torque detected by the torque sensor 73.

  FIG. 5 is a diagram showing an outline of the configuration of the developing device 10A according to the fourth embodiment. Referring to FIG. 5, in the configuration of developing device 10A of the fourth embodiment, in addition to the configuration of developing device 10 of the first embodiment shown in FIG. A torque sensor 73 is provided between the two.

  For example, as the torque detected by the torque sensor 73 increases, the control unit 210 reduces the difference in rotational speed between the conveying members 31 and 32 or increases the period of change in rotational speed. , 72 are controlled.

  When the fluidity of the developer 23 changes due to the surrounding environment of the developing device 10, the usage history of the developer 23, the change in toner density, or the like, excessive stirring energy may be given to the developer 23. . However, as in the fourth embodiment, control is performed so that the stirring energy applied to the developer 23 does not become excessive by changing the difference in the conveyance speed of the plurality of conveyance members 31 and 32 according to the torque. Can do.

  The torque sensor 73 may be provided at another location, for example, between the motor 72 and the conveying member 32. Further, as long as the flowability of the developer 23 in the conveyance path can be detected, the torque sensor 73 is not limited to be provided between the motor and the conveyance member, and another configuration may be used.

[Fifth Embodiment]
FIG. 6 is a diagram schematically illustrating the configuration of the developing devices 10B and 10C according to the fifth embodiment. Referring to FIG. 6, in the fifth embodiment, developing devices 10 </ b> B and 10 </ b> C are connected to communicating portions on the downstream side of conveyance path 74 and the upstream side of conveyance path 75, respectively, and stay portions 76 </ b> B for developer 23. 76C.

  In the developing device 10 according to the first embodiment or the like, as shown in FIG. 6A, the width of the staying portion 76A is set to L1 by the partition wall portion 43 that separates the conveying path 74 and the conveying path 75. I made it.

  On the other hand, as shown in FIG. 6B, in the developing device 10B, the shaft portion on the side of the staying portion 76B of the conveying members 31A and 32A is made more than the conveying members 31 and 32 of the first embodiment or the like. Also, the width of the staying part 76B is set to L2 (> L1) so that the volume of the staying part 76B is increased. For example, it can be considered that L2 = n1 / n2 × L1. If n1 and n2 are variable, it is conceivable to calculate L2 using n1 and n2 when the difference is the largest.

  As shown in FIG. 6C, in the developing device 10C, the staying part 76C is made shorter by making the staying part 76B side of the partitioning part 43A shorter than the partitioning part 43 in the first embodiment or the like. Is set to L3 (> L1) so that the volume of the staying portion 76C is increased. For example, it can be considered that L3 = n1 / n2 × L1. When n1 and n2 are variable, it is conceivable to calculate L3 using n1 and n2 when the difference is the largest.

  FIG. 7 is a diagram illustrating the liquid level of the developer 23 of the developing devices 10B and 10C according to the fifth embodiment. When the rotation speed of the conveyance member 31 is made higher than the rotation speed of the conveyance member 32, as shown in FIG. 7A, the liquid level in the conveyance path 74 becomes higher, so that the developer 23 on the developer carrier 11 is moved to. The contact area becomes larger. At this time, since the supply amount of the developer 23 to the developer carrier 11 becomes excessive, the amount of scattering increases both during printing and during warm-up.

  On the other hand, as shown in FIGS. 6 (B) and 6 (C), when the volumes of the staying portions 76B and 76C are increased, as shown in FIGS. 7 (B) and 7 (C), the conveyance is performed. Since the liquid level of the path 74 can be prevented from becoming higher than that shown in FIG. 7A, the contact area of the developer carrier 11 with the developer 23 can be reduced. As a result, the supply amount of the developer 23 to the developer carrier 11 becomes appropriate, and the exposure of the developer 23 from the developer carrier 11 to the outside of the developing devices 10B and 10C is reduced, so that the scattering amount is reduced. be able to. That is, the effect of suppressing the scattering of the developer 23 can be enhanced while increasing the stirring energy applied to the developer 23.

  At the same time, when the image forming apparatus 100 is warmed up, it is not necessary to supply the developer 23 to the developer carrier 11, so that the control unit 210 is more than the amount of the developer 23 in the transport path 74 than during printing. It is preferable to control the transport speed of the transport members 31 and 32 so that the number of the transport members 31 and 32 is reduced. Thereby, the above-described effect can be further enhanced.

[Other embodiments]
(1) In the above-described embodiment, as shown in FIG. 3, one motor 71, 72 is provided for each of the plurality of conveying members 31, 32.

  However, the present invention is not limited to this, and a plurality of conveying members may be driven by a single motor. In this case, after the output from one motor is divided into a plurality of outputs by a gear mechanism or the like, the rotational speed of each output is changed to a target value by CVT (Continuously Variable Transmission), and then each conveying member You may make it transmit to.

  You may make it transmit an output to any one conveyance member with the rotational speed of a motor not passing through CVT. Also, when the rotation speed ratio of the plurality of conveying members is constant, the output of the motor can be divided and increased or decelerated and transmitted to each conveying member only by the gear mechanism without using CVT. it can.

  (2) In the above-described embodiment, the two conveying members 31 and 32 are provided in the circulation path of the developer 23 inside the developing device 10. However, the present invention is not limited to this, and three or more conveying members may be provided. In this case, in order to obtain the same effect as that of the above-described embodiment, the control unit 210 is configured so that a difference occurs in the transport speed of the developer 23 transported by each of the two transport members adjacent in the circulation path. The operation of the conveying member is controlled.

  (3) In the above-described embodiment, the developer 23 can be transported at the same transport speed as long as the two adjacent transport members 31 and 32 have the same rotational speed. However, the present invention is not limited to this, and the above-described embodiment can be applied even when the conveyance speeds of the respective developers 23 are different when the rotation speeds of two adjacent conveyance members are the same. . In this case, the control unit 210 may control the rotational speed of the transport member so that a difference occurs in the transport speed of the developer 23 transported by each of the two transport members adjacent in the circulation path.

  (4) In the above-described embodiment, the conveying members 31 and 32 are rotated and agitated while conveying the developer in the rotation axis direction. However, the present invention is not limited to this, and the conveying member may be any other member as long as it stirs while conveying the developer in a predetermined direction along the circulation path. There may be. In this case, the control unit may control the operation of the transport member so that a difference occurs in the transport speed of the developer transported by each of the two transport members adjacent in the circulation path.

[Summary]
(1) As described above, the image forming apparatus 100 includes the developing devices 10, 10 </ b> A to 10 </ b> C that supply the developer 23 containing toner to the developing region 62 where the toner image is formed, and the control unit 210. Prepare. The developing devices 10, 10 </ b> A to 10 </ b> C include a plurality of transport members 31 and 32 that stir while transporting the developer 23 in a predetermined direction along the circulation path. As described in the first embodiment and the like, the controller 210 controls the transport member so that a difference occurs in the transport speed of the developer 23 transported by each of the two transport members 31 and 32 adjacent in the circulation path. The operations of 31 and 32 are controlled.

  Thereby, more agitation energy can be given to the developer 23 by the conveying members 31 and 32. As a result, the charge amount of the developer 23 can be stabilized efficiently.

  (2) The conveying members 31 and 32 are rotated and agitated while conveying the developer 23 in the rotation axis direction. As described in the first embodiment and the like, the controller 210 controls the transport member so that a difference occurs in the transport speed of the developer 23 transported by each of the two transport members 31 and 32 adjacent in the circulation path. The rotational speeds 31 and 32 are controlled.

  Accordingly, more agitation energy can be given to the developer 23 by the rotation of the conveying members 31 and 32. As a result, the charge amount of the developer 23 can be efficiently stabilized by the rotation of the transport members 31 and 32.

  (3) Each of the transport members 31 and 32 can transport the developer 23 at the same transport speed as long as the rotation speed is the same. As described in the first embodiment and the like, the control unit 210 controls the rotation speeds of the conveyance members 31 and 32 so that a difference occurs between the rotation speeds of the two conveyance members 31 and 32 adjacent in the circulation path. Control.

  Thereby, more agitation energy can be given to the developer 23 due to the difference in rotational speed between the conveying members 31 and 32. As a result, the charge amount of the developer 23 can be efficiently stabilized by the difference in the rotation speeds of the transport members 31 and 32.

  (4) As described in the first embodiment and the like, the control unit 210 makes the conveyance speed of the conveyance member 31 faster than the conveyance speed of the conveyance member 32 farther from the development region 62 than the conveyance member 31. The conveying speed of the conveying members 31 and 32 is controlled.

  Thereby, since the amount of the developer 23 supplied to the developer carrier 11 can be suppressed, the amount of the developer 23 returned to the developer recovery region 13 is reduced, and the developer recovery region 13 is hardly clogged. As a result, the flow of the developer 23 that passes through the regulating member 16 is less likely to become unstable, so that it is difficult for excessive stress to be applied to the developer 23 or the developer 23 is difficult to scatter.

  (5) As described in the second embodiment, the controller 210 controls the transport speeds of the two transport members 31 and 32 adjacent to each other in the circulation path before supplying the developer 23 to the development area 62. The difference is changed according to the time during which the developer 23 is left without stirring.

  Accordingly, more agitation energy can be given to the developer 23 according to the time the developer 23 is left without agitation, and the charging stability rate of the developer 23 can be increased efficiently. .

  (6) As described in the third embodiment, the control unit 210 periodically changes the difference between the conveyance speeds of the two conveyance members 31 and 32 adjacent in the circulation path.

  Thereby, the liquid level of the developer 23 in the conveyance path 74 with which the developer carrier 11 is in contact can be lowered. As a result, clogging of the developer 23 can be reduced.

  (7) As described in the fourth embodiment, a torque sensor 73 that detects torque for operating one of the conveying members 31 and 32 is further provided. The control unit 210 changes the difference in conveyance speed between the two conveyance members 31 and 32 adjacent to each other in the circulation path in accordance with the torque detected by the torque sensor 73.

  Thereby, it is possible to control so that the stirring energy given to the developer 23 by the transport members 31 and 32 does not become excessive.

  (8) As described in the fifth embodiment, the control unit 210 develops during printing before supplying the developer 23 to the developing area 62 during warm-up of the image forming apparatus 100. The conveyance speeds of the conveyance members 31 and 32 are controlled so that the amount of the developer 23 in the conveyance path 74 that is a portion near the development area 62 in the circulation path is smaller than when the developer 23 is supplied to the area 62.

  Accordingly, the liquid level of the developer 23 in the transport path 74 can be prevented from becoming high during the warm-up, so that the contact area of the developer carrier 11 with the developer 23 can be reduced. As a result, since the exposure of the developer 23 from the developer carrier 11 to the outside of the developing device 10 is reduced, the amount of scattering can be reduced.

  (9) The developing devices 10 </ b> B and 10 </ b> C further include a developer carrier 11 that supplies the developer 23 to the developing region 62. The plurality of transport members 31 and 32 are respectively provided in a transport path 74 along the developer carrier 11 in the circulation path and a transport path 75 communicating with a downstream communication portion with respect to a predetermined direction of the transport path 74. . The developing devices 10B and 10C further include retention portions 76B and 76C that retain the developer 23 in the communication portion.

  Accordingly, the liquid level of the developer 23 in the transport path 74 can be prevented from becoming high during the warm-up, so that the contact area of the developer carrier 11 with the developer 23 can be reduced. As a result, since the exposure of the developer 23 from the developer carrier 11 to the outside of the developing device 10 is reduced, the amount of scattering can be reduced.

  The above-described embodiment can be regarded as the invention of the image forming apparatus 100 and also as the invention of the developing devices 10 and 10A to 10C.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  10, 10A, 10B, 10C Developing device, 11 Developer carrier, 13 Developer collecting area, 15 Toner replenishing section, 15h Hopper, 15i Toner replenishing port, 16 Regulating member, 17 Developer tank, 20 Casing, 21 ATDC sensor , 22 Supply toner, 23 Developer, 25 Magnet roller, 26 Sleeve roller, 31, 31A, 32, 32A Conveying member, 43, 43A Partition, 51 Image carrier, 53 Charging member, 54 Transfer roller, 55 Cleaning blade, 56 Exposure device, 62 Development area, 71, 72 Motor, 73 Torque sensor, 74, 75 Conveyance path, 76A, 76B, 76C Retention unit, 100 Image forming device, 110 Transfer medium, 210 Control unit, 220 Storage unit, 230 Operation Section, 240 display section, 260 communication section, 270 scanner section, 2 0 printer unit, 900 private network.

Claims (10)

A developing device for supplying a developer containing toner to a developing region where a toner image is formed;
A control unit,
The developing device includes:
A plurality of conveying members that stir while conveying the developer in a predetermined direction along the circulation path;
The image forming apparatus, wherein the control unit controls the operation of the conveying member such that a difference occurs in the conveying speed of the developer conveyed by each of the two conveying members adjacent in the circulation path. The conveying member is agitated while being conveyed in the rotation axis direction by being rotated,
2. The control unit according to claim 1, wherein the control unit controls a rotation speed of the transport member so that a difference occurs in a transport speed of the developer transported by each of the two transport members adjacent in the circulation path. Image forming apparatus. Each of the transport members can transport the developer at the same transport speed as long as the rotation speed is the same.
The image forming apparatus according to claim 2, wherein the control unit controls the rotation speed of the transport member so that a difference is generated between the rotation speeds of the two transport members adjacent in the circulation path.   The control unit controls the transport speed of the transport member so that the transport speed of the first transport member is faster than the transport speed of the second transport member farther from the development region than the first transport member. Item 2. The image forming apparatus according to Item 1.   Before supplying the developer to the development area, the control unit leaves the difference in transport speed between the two transport members adjacent in the circulation path without stirring the developer. The image forming apparatus according to claim 1, wherein the image forming apparatus is changed according to time.   The image forming apparatus according to claim 1, wherein the control unit periodically changes a difference in conveyance speed between two conveyance members adjacent in the circulation path. A detector for detecting torque for operating any of the conveying members;
The image forming apparatus according to claim 1, wherein the control unit changes a difference in conveyance speed between two conveyance members adjacent to each other in the circulation path according to a torque detected by the detection unit.   The controller may reduce the amount of the developer in a portion near the development area of the circulation path before supplying the developer to the development area than when supplying the developer to the development area. The image forming apparatus according to claim 1, wherein the conveyance speed of the conveyance member is controlled so as to be. The developing device includes:
A supply member for supplying the developer to the development region;
The plurality of transport members communicate with a first transport member provided in a first circulation path along the supply member in the circulation path, at a communication portion on the downstream side with respect to the predetermined direction of the first circulation path. A second conveying member provided in two circulation paths,
The developing device includes:
The image forming apparatus according to claim 1, further comprising a retention portion that retains the developer in the communication portion. A developing device that supplies a developer containing toner to a developing region where a toner image is formed, and includes a plurality of conveying members that agitate while conveying the developer in a predetermined direction along a circulation path;
Each of the transport members is operable to cause a difference in transport speed of the developer transported by each of the two transport members adjacent in the circulation path.

Images