JP6327228B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus including a developing device that supplies a developer to an image carrier.

  An electrophotographic image forming apparatus irradiates a peripheral surface of an image carrier (photosensitive drum) with light based on image information read from an original image or image information transmitted from an external device such as a computer. An electrostatic latent image is formed, toner is supplied from the developing device to the electrostatic latent image to form a toner image, and then the toner image is transferred to a sheet. The paper after the transfer process is subjected to a toner image fixing process and then discharged to the outside.

  By the way, in recent years, in the image forming apparatus, the configuration of the apparatus becomes complicated with the progress of color printing and high-speed processing, and the toner stirring member in the developing device is forced to rotate at high speed to cope with high-speed processing. . In particular, in a development method using a two-component developer including a magnetic carrier and a toner and using a magnetic roller (toner supply roller) that carries the developer and a development roller that carries only the toner, the development roller and the magnetic roller In the opposite portion, only the toner is carried on the developing roller by the magnetic brush formed on the magnetic roller, and the toner that has not been used for development is peeled off from the developing roller. Therefore, toner scattering is likely to occur in the vicinity of the facing portion between the developing roller and the magnetic roller, and the toner floating in the developing device accumulates around the earbrush blade (regulating blade), and the accumulated toner aggregates. If the toner adheres to the developing roller, the toner may be dropped and an image defect may occur.

  Therefore, for example, Patent Document 1 discloses a developing device that uses a two-component developer including a magnetic carrier and a toner and uses a magnetic roller that supports the developer and a developing roller that supports only the toner. Development provided with a toner receiving support member facing the roller, a toner receiving member that is disposed along the longitudinal direction of the toner receiving support member and that receives toner falling from the developing roller, and a vibration generating means that vibrates the toner receiving member An apparatus is disclosed.

  Patent Document 2 discloses a developing device in which a sheet-like vibration adjusting member is disposed at a predetermined distance from both ends of the toner receiving support member in the longitudinal direction. In this developing device, when the toner receiving member vibrates, the toner receiving member comes into contact with the vibration adjusting member, so that the free end of the toner receiving member vibrates so as to draw an arc and vibrates so as to be deposited on the free end side of the toner receiving member. Move the toner to the fulcrum side.

JP 2012-208469 A Japanese Patent Laying-Open No. 2014-6411

  In the configurations of Patent Documents 1 and 2, the toner receiving member is vibrated at predetermined intervals to shake off the accumulated toner, thereby preventing toner drop. However, since the amount of floating toner generated varies depending on the charge attenuation level of the toner in the developing device, the amount of toner deposited on the toner receiving member also varies.

  Specifically, the lower the charge attenuation level of the toner, the more the charge amount of the toner on the developing roller is held, so the amount of floating toner generated is reduced. On the other hand, as the charge attenuation level of the toner increases, the charge amount of the toner on the developing roller decreases without being retained, so that the amount of floating toner generated increases and a large amount of toner accumulates on the toner receiving member. When the toner receiving member is vibrated in this state, a large amount of the aggregated toner falls on the magnetic roller at a time, and cannot be completely collected in the magnetic brush on the magnetic roller and adheres to the developing roller. There was a risk of toner dropping.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an image forming apparatus capable of maintaining the recovery performance of toner deposited on a toner receiving member even when the charge attenuation level of toner in a two-component developer changes. And

  In order to achieve the above object, a first configuration of the present invention is an image forming apparatus including an image carrier, a developing device, and a control unit. An electrostatic latent image is formed on the image carrier. The developing device includes a developing roller, a toner supply roller, a regulating blade, a casing, a toner receiving support member, a toner receiving member, and vibration generating means, and includes an electrostatic latent image formed on the image carrier. Develop the image. The developing roller is disposed to face the image carrier and supplies toner to the image carrier in a region facing the image carrier. The toner supply roller is disposed to face the developing roller, and supplies toner to the developing roller in a region facing the developing roller. The regulating blade is disposed to face the toner supply roller at a predetermined interval. The casing houses a developing roller, a toner supply roller, and a regulating blade. The toner receiving support member is disposed in the casing and faces the developing roller or the toner supply roller between the regulating blade and the image carrier. The toner receiving member has a toner receiving surface that is disposed along the longitudinal direction of the toner receiving support member and receives toner falling from the developing roller. The vibration generating means vibrates the toner receiving member. The control unit controls driving of the developing device. The image forming apparatus can execute a toner recovery mode in which the toner receiving member is vibrated by the vibration generating means during non-image formation to shake off the toner deposited on the toner receiving surface. The toner recovery mode is executed by alternately repeating a driving period in which the vibration generating unit is continuously driven for a predetermined time and a stop period in which the driving of the vibration generating unit is stopped for a predetermined time. When the charge decay constant of the toner in the two-component developer stored in the casing is greater than or equal to a predetermined value, the control unit determines the number of repetitions of the drive period and the stop period compared to when the charge decay constant is less than the predetermined value. increase.

  According to the first configuration of the present invention, when the charge attenuation constant of the toner is higher than a predetermined value, the toner charge attenuation is increased by increasing the number of repetitions of the drive period and the stop period of the vibration generating unit in the toner recovery mode. In a state where the constant is high and the floating toner is likely to be generated, the total driving time of the vibration generating means can be lengthened to collect more toner deposited on the toner receiving member.

1 is a schematic configuration diagram of a color printer 100 according to an embodiment of the present invention. Side sectional view of the developing device 3a mounted on the color printer 100 of the present invention. Block diagram showing the control path of the color printer 100 The perspective view which looked at the toner receiving support member 35 used for the developing device 3a from the inside of the developing container 20 The perspective view of the support member main body 36 which comprises the toner receiving support member 35 The perspective view which looked at the toner receiving member 37 which comprises the toner receiving support member 35 from the back surface side The perspective view which shows the internal structure of the vibration generator 40 with which the toner receiving member 37 is mounted | worn. Front view of vibration motor 43 Side view of the vibration motor 43 as seen from the side of the vibration weight 50 FIG. 4 is a side cross-sectional view around the toner receiving support member 35 of the developing device 3a, showing a cross section near the vibration motor 43; 10 is a partially enlarged view of the toner receiving support member 35 in FIG. Timing chart showing operation of toner recovery mode in color printer 100 of the present invention FIG. 10 is a timing chart showing another operation pattern of the vibration motor 43 in the toner recovery mode, and shows a pattern in which the number of repetitions of the operation cycle of the vibration motor 43 is increased. It is a timing chart which shows the other operation pattern of the vibration motor 43 in toner collection mode, and is a figure which shows the pattern which extended the drive time of the vibration motor 43 in steps. Side sectional view showing the developing device 3a of the present invention in which the arrangement of the toner supply roller 30 and the developing roller 31 is reversed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an image forming apparatus on which developing devices 3a to 3d of the present invention are mounted. Here, a tandem color printer is shown. In the main body of the color printer 100, four image forming portions Pa, Pb, Pc, and Pd are sequentially arranged from the upstream side in the transport direction (the right side in FIG. 1). These image forming portions Pa to Pd are provided corresponding to images of four different colors (cyan, magenta, yellow, and black), and cyan, magenta, and yellow are respectively performed by charging, exposure, development, and transfer processes. And a black image are sequentially formed.

  These image forming portions Pa to Pd are provided with photosensitive drums 1a, 1b, 1c and 1d which carry visible images (toner images) of the respective colors, and are further illustrated by a driving means (not shown). 1, an intermediate transfer belt 8 that rotates in the clockwise direction is provided adjacent to each of the image forming portions Pa to Pd. The toner images formed on the photosensitive drums 1a to 1d are sequentially primary-transferred and superimposed on the intermediate transfer belt 8 that moves while contacting the photosensitive drums 1a to 1d. Thereafter, the toner image primarily transferred onto the intermediate transfer belt 8 is secondarily transferred onto a transfer paper P as an example of a recording medium by the action of the secondary transfer roller 9. Further, the transfer paper P onto which the toner image is secondarily transferred is discharged from the main body of the color printer 100 after the toner image is fixed in the fixing unit 13. An image forming process for each of the photosensitive drums 1a to 1d is executed while rotating the photosensitive drums 1a to 1d in the counterclockwise direction in FIG.

  The transfer paper P on which the toner image is secondarily transferred is accommodated in a paper cassette 16 disposed at the lower part of the main body of the color printer 100, and the secondary transfer roller 9 via the paper feed roller 12a and the registration roller pair 12b. And the intermediate transfer belt 8 to be described later is conveyed to a nip portion with a driving roller 11. A sheet made of dielectric resin is used for the intermediate transfer belt 8, and a (seamless) belt having no seam is mainly used. Further, a blade-like belt cleaner 19 for removing toner remaining on the surface of the intermediate transfer belt 8 is disposed on the downstream side of the secondary transfer roller 9.

  Next, the image forming units Pa to Pd will be described. Around and below the photosensitive drums 1a to 1d arranged to be rotatable, chargers 2a, 2b, 2c and 2d for charging the photosensitive drums 1a to 1d, and image information to each of the photosensitive drums 1a to 1d. The exposure device 5 for exposing the toner, the developing devices 3a, 3b, 3c and 3d for forming toner images on the photosensitive drums 1a to 1d, and the developer (toner) remaining on the photosensitive drums 1a to 1d are removed. Cleaning parts 7a, 7b, 7c and 7d are provided.

  When image data is input from a host device such as a personal computer, first, the surfaces of the photosensitive drums 1a to 1d are uniformly charged by the chargers 2a to 2d, and then light is irradiated according to the image data by the exposure device 5. The electrostatic latent images corresponding to the image data are formed on the respective photosensitive drums 1a to 1d. Each of the developing devices 3a to 3d is filled with a predetermined amount of a two-component developer containing toner of each color of cyan, magenta, yellow, and black. In addition, when the ratio of the toner in the two-component developer filled in each developing device 3a to 3d falls below a specified value due to the formation of a toner image described later, each developing device 3a to 3d is transferred from the toner container 4a to 4d. Toner is replenished. The toner in the developer is supplied onto the photosensitive drums 1a to 1d by the developing devices 3a to 3d and electrostatically adheres to the electrostatic latent image formed by the exposure from the exposure device 5. A toner image is formed.

  The primary transfer rollers 6a to 6d apply an electric field at a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d, and cyan, magenta, yellow, and yellow on the photosensitive drums 1a to 1d. A black toner image is primarily transferred onto the intermediate transfer belt 8. These four color images are formed with a predetermined positional relationship predetermined for forming a predetermined full-color image. Thereafter, in preparation for the subsequent formation of a new electrostatic latent image, the toner remaining on the surfaces of the photosensitive drums 1a to 1d after the primary transfer is removed by the cleaning units 7a to 7d.

  The intermediate transfer belt 8 is stretched over an upstream driven roller 10 and a downstream drive roller 11, and the intermediate transfer belt 8 rotates clockwise as the drive roller 11 is rotated by a drive motor (not shown). When rotation in the direction starts, the transfer paper P is conveyed from the registration roller pair 12b to the nip portion (secondary transfer nip portion) between the driving roller 11 and the secondary transfer roller 9 provided adjacent thereto at a predetermined timing. Then, the full color image on the intermediate transfer belt 8 is secondarily transferred onto the transfer paper P. The transfer sheet P on which the toner image is secondarily transferred is conveyed to the fixing unit 13.

  The transfer paper P conveyed to the fixing unit 13 is heated and pressed by the fixing roller pair 13a to fix the toner image on the surface of the transfer paper P, and a predetermined full-color image is formed. The transfer paper P on which the full-color image is formed is distributed in the transport direction by the branching portion 14 that branches in a plurality of directions. When an image is formed on only one side of the transfer paper P, it is discharged as it is onto the discharge tray 17 by the discharge roller pair 15.

  On the other hand, when forming images on both sides of the transfer paper P, the transfer paper P that has passed through the fixing unit 13 is once conveyed in the direction of the discharge roller pair 15. Then, after the trailing edge of the transfer paper P has passed through the branch portion 14, the discharge roller pair 15 is rotated in the reverse direction and the transport direction of the branch portion 14 is switched. As a result, the transfer paper P is distributed from the rear end to the paper transport path 18 and is transported again to the secondary transfer nip portion with the image surface reversed. Then, the next toner image formed on the intermediate transfer belt 8 is secondarily transferred to the surface of the transfer paper P on which the image is not formed by the secondary transfer roller 9. The transfer paper P onto which the toner image has been secondarily transferred is conveyed to the fixing unit 13 where the toner image is fixed and then discharged onto the discharge tray 17.

  FIG. 2 is a side cross-sectional view of the developing device 3 a mounted on the color printer 100. 2 shows a state viewed from the back side of FIG. 1, and the arrangement of each member in the developing device 3a is opposite to that in FIG. Further, in the following description, the developing device 3a disposed in the image forming unit Pa of FIG. 1 is illustrated, but the configuration of the developing devices 3b to 3d disposed in the image forming units Pb to Pd is basically the same. Therefore, explanation is omitted.

  As shown in FIG. 2, the developing device 3a includes a developing container (casing) 20 in which a two-component developer (hereinafter simply referred to as a developer) composed of toner and a magnetic carrier is stored. The partition wall 20a is divided into an agitating and conveying chamber 21 and a supply and conveying chamber 22. In the agitating / conveying chamber 21 and the supply / conveying chamber 22, the agitating / conveying screw 25 a for supplying toner (positively charged toner) supplied from the toner container 4 a (see FIG. 1) with the carrier, agitating and charging, and the supplying and conveying Each screw 25b is rotatably arranged.

  Then, the developer is agitated by the agitating / conveying screw 25a and the supply / conveying screw 25b and conveyed in the axial direction (perpendicular to the paper surface of FIG. 2) to pass through the developer (not shown) formed at both ends of the partition wall 20a. It circulates between the stirring and conveying chamber 21 and the supply and conveying chamber 22 through the path. That is, a developer circulation path is formed in the developer container 20 by the agitating / conveying chamber 21, the supply / conveying chamber 22, and the developer passage.

  The developing container 20 extends obliquely upward to the right in FIG. 2. A toner supply roller 30 (developer carrying member) is disposed above the supply / conveying screw 25 b in the developing container 20. A developing roller 31 is disposed diagonally upward. The developing roller 31 faces the photosensitive drum 1a (see FIG. 1) on the opening side (the right side in FIG. 2) of the developing container 20, and the toner supply roller 30 and the developing roller 31 are shown in FIG. 2 rotates counterclockwise.

  In the agitating / conveying chamber 21, a toner concentration detection sensor 27 is disposed so as to face the agitating / conveying screw 25a. The toner concentration detection sensor 27 detects the ratio (T / C) of the toner to the carrier in the developer. Based on the detection result of the toner concentration detection sensor 27, a toner supply port (not shown) is opened from the toner container 4a. Thus, the toner is supplied to the agitating / conveying chamber 21. As the toner concentration detection sensor 27, for example, a magnetic permeability sensor that detects the magnetic permeability of the developer in the developing container 20 is used.

  The toner supply roller 30 is composed of a non-magnetic rotating sleeve that rotates counterclockwise in FIG. 2 and a fixed magnet body having a plurality of magnetic poles contained in the rotating sleeve.

  The developing roller 31 includes a cylindrical developing sleeve that rotates counterclockwise in FIG. 2 and a developing roller side magnetic pole that is fixed in the developing sleeve. It faces with a predetermined gap at the facing position (facing position). The developing roller side magnetic pole has a different polarity from the opposing magnetic pole (main pole) of the fixed magnet body.

  Further, a spike cutting blade 33 is attached to the developing container 20 along the longitudinal direction of the toner supply roller 30 (a direction perpendicular to the paper surface of FIG. 2), and the spike cutting blade 33 rotates in the rotation direction of the toner supply roller 30. In the counterclockwise direction in FIG. 2, the developing roller 31 and the toner supply roller 30 are positioned on the upstream side. A slight gap (gap) is formed between the tip of the ear cutting blade 33 and the surface of the toner supply roller 30.

  A DC voltage (hereinafter referred to as Vslv (DC)) and an AC voltage (hereinafter referred to as Vslv (AC)) are applied to the developing roller 31, and a DC voltage (hereinafter referred to as Vmag (DC)) is applied to the toner supply roller 30. ) And an alternating voltage (hereinafter referred to as Vmag (AC)). These DC voltage and AC voltage are applied from the developing bias power supply 53 to the developing roller 31 and the toner supply roller 30 via the bias control circuit 55 (both see FIG. 3).

  As described above, the developer is agitated by the agitating / conveying screw 25a and the supply / conveying screw 25b, and the toner is charged by circulating through the agitating / conveying chamber 21 and the supplying / conveying chamber 22 in the developing container 20, and the supply / conveying screw 25b. The developer is conveyed to the toner supply roller 30. Then, a magnetic brush (not shown) is formed on the toner supply roller 30. After the layer thickness of the magnetic brush on the toner supply roller 30 is regulated by the earbrushing blade 33, the toner supply roller 30 and the developing roller 31 are separated. A thin toner layer is formed on the developing roller 31 by a potential difference ΔV between Vmag (DC) applied to the toner supply roller 30 and Vslv (DC) applied to the developing roller 31 and a magnetic field.

  The thickness of the toner layer on the developing roller 31 varies depending on the resistance of the developer, the rotational speed difference between the toner supply roller 30 and the developing roller 31, and the like, but can be controlled by ΔV. When ΔV is increased, the toner layer on the developing roller 31 is thickened, and when ΔV is decreased, the toner layer is thinned. The range of ΔV at the time of development is generally about 100V to 350V.

  The toner thin layer formed on the developing roller 31 by contact with the magnetic brush on the toner supply roller 30 is conveyed to a facing portion (facing region) between the photosensitive drum 1 a and the developing roller 31 by the rotation of the developing roller 31. The Since Vslv (DC) and Vslv (AC) are applied to the developing roller 31, the toner flies due to a potential difference with the photosensitive drum 1a, and the electrostatic latent image on the photosensitive drum 1a is developed. .

  Remaining toner that is not used for development is conveyed again to the opposite portion between the developing roller 31 and the toner supply roller 30 and is collected by the magnetic brush on the toner supply roller 30. The magnetic brush is peeled off from the toner supply roller 30 at the same polarity portion of the fixed magnet body, and then falls into the supply conveyance chamber 22.

  Thereafter, a predetermined amount of toner is replenished from a toner replenishing port (not shown) based on the detection result of the toner concentration detecting sensor 27, and uniform with an appropriate toner concentration again while circulating through the supply transport chamber 22 and the stirring transport chamber Becomes a two-component developer charged in a negative direction. This developer is again supplied onto the toner supply roller 30 by the supply agitating screw 25 b to form a magnetic brush, and is conveyed to the ear cutting blade 33.

  A toner receiving and supporting member 35 having a triangular cross-section projecting inward of the developing container 20 is provided in the vicinity of the developing roller 31 on the right side wall in FIG. As shown in FIG. 2, the toner receiving support member 35 is disposed along the longitudinal direction of the developing container 20 (the direction perpendicular to the paper surface of FIG. 2). A wall portion that faces the developing roller 31 and is inclined downward from the developing roller 31 toward the toner supply roller 30 is configured. On the upper surface of the toner receiving support member 35, a toner receiving member 37 is attached along the longitudinal direction for receiving the toner that is peeled off from the developing roller 31 and falls.

  FIG. 3 is a block diagram illustrating an example of a control path used in the color printer 100 of the present invention. In addition, since various controls of each part of the apparatus are performed when the color printer 100 is used, the control path of the entire color printer 100 becomes complicated. Therefore, here, a portion of the control path that is necessary for the implementation of the present invention will be mainly described.

  The bias control circuit 55 is connected to the charging bias power source 52, the developing bias power source 53, and the transfer bias power source 54, and operates each of these power sources in accordance with an output signal from the control unit 90. In accordance with a control signal from the control circuit 55, the charging bias power source 52 is supplied to the charging rollers in the charging devices 2a to 2d, and the developing bias power source 53 is transferred to the toner supply roller 30 and the developing roller 31 in the developing devices 3a to 3d. A predetermined bias 54 is applied to the primary transfer rollers 6a to 6d and the secondary transfer roller 9, respectively.

  The reader / writer module 57 faces the IC chip 58 attached to the toner containers 4a to 4d in a state where the toner containers 4a to 4d are accommodated in the image forming apparatus 100 (state shown in FIG. 1). . When data is written to the memory of the IC chip 58, the reader / writer module 57 generates an electromagnetic wave including a write command and data. The IC chip 58 is activated by receiving the electromagnetic wave, and sends data to the memory according to the write command. Data is written. When reading data from the memory of the IC chip 58, the reader / writer module 57 generates an electromagnetic wave including a read command, and the IC chip 58 is activated by receiving the electromagnetic wave and stores it in the memory according to the read command. The read data is transmitted to the reader / writer module 57.

  The image input unit 60 is a receiving unit that receives image data transmitted to the color printer 100 from a personal computer or the like. The image signal input from the image input unit 60 is converted into a digital signal and then sent to the temporary storage unit 94.

  The operation unit 70 is provided with a liquid crystal display unit 71 and LEDs 72 indicating various states, and displays the state of the color printer 100 and displays the image forming status and the number of copies to be printed. Various settings of the color printer 100 are performed from a printer driver of a personal computer.

  In addition, the operation unit 70 includes a start button for instructing the user to start image formation, a stop / clear button used when the image formation is stopped, and various settings of the color printer 100 when making the default settings. A reset button or the like to be used is provided.

  The in-machine temperature sensor 80 detects the temperature inside the color printer 100, particularly the temperature of the surface or the periphery of the photosensitive drums 1a to 1d, and is disposed in the vicinity of the image forming units Pa to Pd.

  The control unit 90 includes a central processing unit (CPU) 91 as a central processing unit, a read only memory (ROM) 92 that is a read-only storage unit, a random access memory (RAM) 93 that is a readable / writable storage unit, A plurality of (two in this case) that transmit control signals to and receive input signals from the operation unit 50, such as a temporary storage unit 94 for storing image data and the like, a counter 95, and each device in the color printer 100. At least an I / F (interface) 96 is provided. For example, detection signals from the reader / writer module 57 and the in-machine temperature / humidity sensor 80 are transmitted to the CPU 91 in the control unit 90 via the I / F (interface) 96.

  The ROM 92 stores a program for controlling the color printer 100, numerical values necessary for control, and the like that are not changed during use of the color printer 100. The RAM 93 stores necessary data generated during control of the color printer 100, data temporarily required for control of the color printer 100, and the like. The RAM 93 (or ROM 92) also stores a table associating the toner density in the developing devices 3a to 3d with the operation pattern of the vibration motor when executing the toner recovery mode, as will be described later. The temporary storage unit 94 temporarily stores an image signal input from an image input unit (not shown) that receives image data transmitted from a personal computer or the like and converted into a digital signal. The counter 95 counts the accumulated number of printed sheets.

  The control unit 90 transmits a control signal from the CPU 91 to the respective units and devices in the color printer 100 through the I / F 96. In addition, a signal indicating the state and an input signal are transmitted from each part or device to the CPU 91 through the I / F 96. Examples of the parts and devices controlled by the control unit 90 include, for example, the image forming units Pa to Pd, the exposure device 5, the intermediate transfer belt 8, the secondary transfer roller 9, the fixing unit 13, the bias control circuit 55, and the image input unit 60. And the operation unit 70 and the like.

  4 is a perspective view of the toner receiving support member 35 used in the developing devices 3a to 3d as viewed from the inside of the developing container 20 (left side in FIG. 2), and FIG. 5 is a support member main body constituting the toner receiving support member 35. 36 is a perspective view of the toner receiving member 37 constituting the toner receiving support member 35 as viewed from the inside of the toner receiving support member 35. FIG. FIG. 5 shows a state in which the support member main body 36 is viewed from the mounting direction of the toner receiving member 37.

  The toner receiving support member 35 is attached to a resin supporting member main body 36, a sheet metal toner receiving member 37 that is swingably supported by the supporting member main body 36, and a substantially central portion in the longitudinal direction of the toner receiving member 37. Vibration generator 40 to be operated. The support member main body 36 is formed with a storage portion 36a in which the vibration generating device 40 is stored when the toner receiving member 37 is mounted.

  A film-like seal member 44 is provided at the upper end of the support member main body 36. The seal member 44 extends in the longitudinal direction (left-right direction in FIG. 4) of the support member main body 36 so that the tip portion contacts the surface of the photosensitive drum 1a, and the seal member 44 is in the developing container 20 (see FIG. 2). It has a function of shielding the toner from leaking outside.

  The toner receiving member 37 has a bent shape in which a bent portion 37a is formed along the longitudinal direction, the toner receiving surface 37b facing the developing roller 31 (see FIG. 2) with the bent portion 37a interposed therebetween, and the toner supply roller 30. And a substantially vertical toner dropping surface 37c facing the surface. On one end side in the longitudinal direction of the toner receiving member 37, an engaging portion 38 is formed that engages a contact spring 48 that grounds (grounds) the toner receiving member 37. A lower end portion of the contact spring 48 contacts the spike cutting blade 33 (see FIG. 2) via a conductive spring receiving member (not shown). A holding portion 39 having a pair of holding claws 39 a that hold the vibration generating device 40 is formed at a substantially central portion in the longitudinal direction of the toner receiving member 37. A substrate 45 on which a circuit for controlling driving of the vibration motor 43 (see FIG. 7) and electronic components (not shown) are mounted is fixed to the vibration generator 40 by screws 46.

  Sheet members 41 a and 41 b are attached to the surface of the toner receiving member 37 (the surface facing the developing roller 31 or the toner supply roller 30). The sheet members 41 a and 41 b are formed of a material that prevents toner from adhering to the toner receiving member 37 in order to suppress toner adhesion to the toner receiving member 37. Examples of the material of the sheet members 41a and 41b include a fluororesin sheet.

  FIG. 7 is a perspective view of the vibration generator 40. 7 shows a state in which the substrate 45 (see FIG. 6) is removed from the motor mounting holder 42 so that the inside of the vibration generating device 40 can be seen. The vibration generator 40 includes a motor mounting holder 42 and a vibration motor 43, and the motor mounting holder 42 is formed with a motor holding portion 42 a for holding the vibration motor 43 and a screw hole 42 b for fastening a screw 46. A vibration weight 50 is fixed to the output shaft 43 a of the vibration motor 43. When the vibration generating device 40 is attached to the toner receiving member 37, the output shaft 43 a of the vibration motor 43 is fixed along the longitudinal direction of the toner receiving member 37. A lead wire (not shown) for supplying power to the vibration motor 43 is connected to the motor mounting holder 42.

  FIG. 8 is a front view of the vibration motor 43, and FIG. 9 is a side view of the vibration motor 43 as viewed from the side of the vibration weight 50. When seen from the direction of the output shaft 43a of the vibration motor 43 (the right direction in FIG. 8), the vibration weight 50 has a cam shape in which a notch 50a is formed in a part of the disk as shown in FIG. Thus, the shape is asymmetric with respect to the output shaft 43a. When the output shaft 43a rotates at a speed higher than a predetermined speed, the centrifugal force acting on the notch 50a is smaller than that of the other portions, so that an uneven centrifugal force is applied to the vibration weight 50. As the centrifugal force is transmitted to the output shaft 43a, the vibration motor 43 vibrates. The shape of the vibration weight 50 is not limited to a cam shape, and may be an arbitrary shape that shifts the center of gravity with respect to the output shaft 43a.

  FIG. 10 is a side cross-sectional view showing a cross section (cross section taken along the line XX ′ in FIG. 4) of the toner receiving support member 35 used in the developing device 3a of this embodiment in the vicinity of the vibration motor 43, and FIG. 3 is a partially enlarged view of a toner receiving support member 35. FIG.

  As shown in FIGS. 10 and 11, only the edge 37d on the toner supply roller 30 side of the toner receiving member 37 is in contact with the support member main body 36, and the edge 37e on the opposite side (photosensitive drum 1a side) is It is a free end. The substantially central portion of the toner receiving surface 37b in the width direction (the left-right direction in FIG. 10) is supported by the support member main body 36 via the vibration generator 40. Thereby, the toner receiving member 37 is configured to be swingable with the end edge 37d as a fulcrum. Further, the vibration motor 43 is disposed so that the output shaft 43 a is substantially parallel to the longitudinal direction of the toner receiving member 37.

  The toner receiving member 37 is inclined such that the toner receiving surface 37b facing the developing roller 31 is inclined upward from the toner supply roller 30 side toward the photosensitive drum 1a side, and the toner falling surface 37c facing the toner supply roller 30. Are arranged so as to be substantially vertical.

  The sheet member 41 a is affixed so as to cover the surface of the toner receiving member 37 (toner dropping surface 37 c) including the boundary between the support member main body 36 and the toner receiving member 37 on the ear cutting blade 33 side. The sheet member 41b covers the entire area of the toner receiving surface 37b including the boundary between the support member main body 36 and the toner receiving member 37 on the seal member 44 side, the engaging portion 38, and the holding portion 39 (see FIG. 5). It is pasted. The sheet members 41 a and 41 b prevent toner from adhering to the toner receiving surface 37 b and the toner dropping surface 37 c, as well as toner leakage from the boundary between the toner receiving support member 35 and the toner receiving member 37, and the toner receiving support member 35. This prevents the toner from entering the inside of the printer and the malfunction of the vibration motor 43 due to the toner entering.

  The color printer 100 according to the present embodiment can execute a toner recovery mode in which the toner receiving member 37 in the developing devices 3a to 3d is vibrated by the vibration generating device 40 during non-image formation to shake off the toner accumulated on the toner receiving surface 37b. It is. Specifically, when the output shaft 43a of the vibration motor 43 is rotated at a high speed (for example, about 10,000 rpm) during non-image formation, the excitation weight 50 also rotates at a high speed together with the output shaft 43a. At this time, since an uneven centrifugal force is applied to the vibration weight 50, the vibration generator 40 including the vibration motor 43 and the motor mounting holder 42 vibrates via the output shaft 43a. The toner receiving member 37 to which the vibration generating device 40 is attached also vibrates. Specifically, the toner receiving surface 37b of the toner receiving member 37 vibrates so that the amplitude becomes larger toward the end edge 37e with the end edge 37d as a fulcrum.

  In the toner recovery mode, the output shaft 43a of the vibration motor 43 and the outer peripheral surface of the output shaft 43a facing the toner receiving member 37 are supported from the free end (end edge 37e) of the toner receiving member 37 as a fulcrum (end edge 37d). In the direction of moving toward (counterclockwise in FIG. 11). By rotating the output shaft 43a in this direction, the toner receiving member 37 vibrates so as to move the toner accumulated on the toner receiving surface 37b from the end edge 37e side to the end edge 37d side.

  On the other hand, when the output shaft 43a is rotated in the reverse direction (clockwise in FIG. 11), the toner is moved up from the edge 37d side to the edge 37e side by the vibration of the toner receiving member 37. Therefore, the toner deposited on the toner receiving surface 37b does not slide down. Therefore, by rotating the output shaft 43a of the vibration motor 43 as in the present embodiment, the toner accumulated on the toner receiving surface 37b can be effectively dropped to the region R along a descending gradient.

  The execution timing of the toner recovery mode may be performed every time the printing operation is completed, or at a predetermined timing such as when the number of printed sheets reaches a predetermined number or when the temperature in the developing device 3a exceeds a predetermined level. You may make it do. In addition, the timing for vibrating the toner receiving member 37 and the timing for forward rotation (or reverse rotation) of the developing roller 31 and the toner supply roller 30 may be the same or different. Further, by vibrating the toner receiving member 37 every time the predetermined number of printed sheets is reached, the vibration of the toner receiving member 37 is automatically executed according to the number of printed sheets. Therefore, it is not necessary for the user himself to manually set the vibration of the toner receiving member 37, and it is possible to avoid setting mistakes, forgetting to set, or unnecessary vibration.

  FIG. 12 is a timing chart showing the operation in the toner recovery mode. When executing the toner recovery mode, first, driving of the color developing devices 3a to 3c and the black developing device 3d is started. The development devices 3a to 3d are driven and stopped by turning on / off the main motor 45 (see FIG. 3) or a clutch (not shown) provided between the main motor 45 and the development devices 3a to 3c and the development device 3d. ) Is turned on / off. In this embodiment, when the vibration generator 40 is driven, the toner supply roller 30 and the developing roller 31 are rotated (reversely rotated) in the opposite direction (clockwise direction in FIG. 11) to that during image formation.

  Next, the toner accumulated on the toner receiving surface 37b is shaken off by operating the vibration motor 43 after a time t1 (here, 0.3 seconds) from the start of driving of the developing devices 3a to 3d. The operation pattern of the vibration motor 43 is repeated for a predetermined number of cycles, with the operation of driving the vibration motor 43 for time t2 (drive period) and stopping for only time t3 (stop period) as one cycle. In this embodiment, t2 = 0.6 seconds and t3 = 0.2 seconds, and the time of one cycle (t2 + t3) is 0.8 seconds, and 6 cycles are repeated.

  As shown in FIG. 11, due to the vibration of the toner receiving surface 37b, the toner T accumulated on the toner receiving surface 37b slides downward (in the direction of the white arrow in FIG. 11) along the inclination of the toner receiving surface 37b and becomes substantially vertical. The toner falls freely into a region R sandwiched between the toner dropping surface 37c and the toner supply roller 30. Part of the toner that has fallen from the toner receiving surface 37 b to the region R adheres to the magnetic brush on the toner supply roller 30. A part of the remaining toner that has not adhered to the magnetic brush on the toner supply roller 30 accumulates on the tip of the spike blade 33, but is scraped off by the magnetic brush of the toner supply roller 30 that rotates in the reverse direction. At this time, the spike cutting blade 33 is adjusted by adjusting the magnetic force and arrangement of the magnetic poles (regulatory poles) of the fixed magnet body facing the spike cutting blade 33 so that the spike of the magnetic brush formed on the toner supply roller 30 becomes long. The scraping effect of the toner accumulated on the tip of the toner increases.

  The toner adhering to the magnetic brush on the toner supply roller 30 rotates along the surface of the toner supply roller 30 and passes through the gap between the toner supply roller 30 and the earbrushing blade 33, and is supplied at the same polarity portion of the fixed magnet body. After being peeled off from the roller 30, it is forcibly returned to the supply conveyance chamber 22.

  When the developing roller 31 and the toner supply roller 30 are rotated in the reverse direction, the developer in the developing container 20 overflows from the toner replenishing port, or the developer is biased in the developing container 20 to cause noise in the toner concentration detection sensor. May occur. Therefore, after the developing roller 31 and the toner supply roller 30 are rotated in the reverse direction, the developing roller 31 and the toner supply roller 30 are continuously rotated in the same direction as the image formation (counterclockwise direction in FIG. 11) ( (Forward rotation) is preferable.

  In this embodiment, after the driving of the vibration motor 43 in the final cycle (here, the sixth cycle) is completed, the developing roller 31 and the toner supply roller 30 are turned on for a time t4 (= 0.5 seconds + 8 rotations of the toner supply roller 30). The rotation is continued for only the rotation time of minutes).

  Incidentally, the amount of toner deposited on the toner receiving member 37 varies depending on the charge attenuation level of the toner in the developer. For example, when the toner charge attenuation level is low, the toner charge amount on the developing roller 31 is maintained, so that the toner scattering amount in the developing container 20 is reduced and the toner deposited on the toner receiving member 37 is also reduced. On the other hand, when the charge attenuation level of the toner is high, the toner charge amount on the developing roller 31 is lowered without being held. Therefore, the amount of toner scattered in the developing container 20 increases, and much toner accumulates on the toner receiving member 37. Become. As a result, when the charge attenuation level of the toner is high, toner drop is likely to occur. The charge attenuation level varies depending on the color of toner (whether it is black toner or color toner) and the material.

  The charge attenuation level of the toner can be determined by measuring the charge attenuation constant of the toner. The charge decay constant is a charge decay rate that can be measured using an electrostatic diffusivity measurement device. Specifically, for example, it can be measured as follows.

  First, as a measurement cell, a metal measurement cell in which a recess having an inner diameter of 10 mm and a depth of 1 mm is formed is used. Toner is put into this measurement cell and pushed in from above with a slide glass. Then, the overflowing toner is scraped off from the measurement cell by reciprocating the surface of the measurement cell with the slide glass that has been pushed in. At this time, the degree of pressing with the slide glass is adjusted so that the amount of toner filling the recesses is 0.04 g or more and 0.06 g or less.

Next, the measurement cell filled with toner is left in an environment of 32.5 ° C. and 80% relative humidity for 12 hours, and then placed in the electrostatic diffusivity measurement device in a grounded state, and corona discharge is performed. I do. Then, after 0.7 seconds have elapsed from the end of corona discharge, the surface potential of the toner is continuously measured. Based on the measurement result, a charge decay constant (charge decay rate) α is calculated from the following equation (1).
V = V ₀ exp (−α√t) (1)
In the above formula (1), V represents a surface potential (V), V ₀ represents an initial surface potential (V), α represents a charge decay constant (charge decay rate), and t represents a decay time. (Seconds).

  In the color printer 100 of this embodiment, when the charge decay constant of the toner is equal to or greater than the predetermined value A1, the number of repetitions of the operation cycle of the vibration motor 43 is increased. Specifically, the measured charge decay constant (charge decay level information) is input to the IC chip 58 of the toner containers 4a to 4d, and based on the charge decay constant read by the reader / writer module 57. The total drive time of the vibration motor 43 is varied.

  For example, when the charge decay constant is less than 0.03 (normal toner decay level), as shown in FIG. 12, the drive time t2 = 0.6 seconds during the operation cycle of the vibration motor 43, and the stop time t3. Repeat for 6 cycles with = 0.2 seconds. On the other hand, when the charge decay constant is not less than 0.03 and less than 0.05, as shown in FIG. 13, the drive time t2 = 0.6 seconds and the stop time t3 = 0.2 during one operation cycle of the vibration motor 43. Repeat 11 cycles as seconds.

  As described above, when the charge decay constant of the toner is higher than the predetermined value, the number of repetitions of the operation cycle of the vibration motor 43 is increased, so that the total driving time of the vibration motor 43 is lengthened and deposited on the toner receiving surface 37b. More toner can be collected.

  Further, when the charge decay constant of the toner is further increased, if the toner accumulated on the toner receiving surface 37b is dropped at once by increasing the total driving time of the dynamic motor 43 as shown in FIG. Concentration rises rapidly. As a result, the toner is likely to scatter in the vicinity of the facing portion between the developing roller and the magnetic roller, and the toner may fall off.

  Therefore, in the color printer 100 of this embodiment, when the charge decay constant of the toner is equal to or greater than the predetermined value A2 (A2> A1), the number of repetitions of the operation cycle of the vibration motor 43 is increased and the operation of the vibration motor 43 is performed. The drive time t2 is increased stepwise over a plurality of times from the start.

  For example, when the charge decay constant is 0.05 or more, as shown in FIG. 14, the driving time t2 of the first cycle of the vibration motor 43 is 0.2 seconds, the driving time t2 of the second cycle is 0. The driving time t2 of the third cycle, t2 = 0.4 seconds, the driving time t2 of the fourth cycle is set to 0.5 seconds, the driving time t2 after the sixth cycle is set to 0.6 seconds, and 12 cycles are repeated.

  As a result, the toner deposited on the toner receiving surface 37b does not fall at a time and is collected little by little by the toner supply roller 30, so that the toner concentration in the developer does not rise abruptly, and the occurrence of toner dropping is effective. Can be suppressed. As described above, in the color printer 100 of the present invention, the total driving time of the vibration motor 43 or the driving time per operation of the vibration motor 43 can be changed according to the charge attenuation constant of the toner. Regardless of the charge attenuation level, the occurrence of toner drop can be effectively suppressed.

  The number of repetitions of the operation cycle of the vibration motor 43 in FIG. 13 and the number of times the drive time t2 of the vibration motor 43 in FIG. 14 is increased stepwise can be appropriately set according to the charge attenuation level of the toner.

  By the way, when the toner receiving member 37 is vibrated, the toner supply roller 30 and the developing roller 31 can be rotated forward. By rotating the toner supply roller 30 forward, a part of the toner dropped from the toner receiving surface 37 b to the region R adheres to the magnetic brush on the toner supply roller 30. The remaining toner that has not adhered to the magnetic brush on the toner supply roller 30 passes through the gap between the toner supply roller 30 and the ear cutting blade 33 and falls into the supply conveyance chamber 22.

  Note that by rotating the developing roller 31 and the toner supply roller 30 forward, a part of the toner attached to the magnetic brush of the toner supply roller 30 moves onto the developing roller 31. However, since Vslv (DC) is not applied to the developing roller 31 during non-image formation, the potential difference between the developing roller 31 and the photosensitive drum 1a is zero. Accordingly, even if the developing roller 31 rotates and the toner adheres to the surface of the developing roller 31 and passes through the portion facing the photosensitive drum 1a, the toner does not move toward the photosensitive drum 1a.

  Further, when the toner receiving member 37 is vibrated, Vslv (DC) having the same polarity as the toner may be applied to the developing roller 31 without applying Vmag (DC) to the toner supply roller 30. In this way, a potential difference in the direction in which the toner moves from the developing roller 31 to the toner supply roller 30 is generated, so that the toner shaken off from the toner receiving member 37 and attached to the toner supply roller 30 moves to the developing roller 31. This phenomenon can be effectively suppressed.

  When the developing roller 31 and the toner supply roller 30 are rotated forward when the toner receiving member 37 is vibrated, as shown in FIG. 12, the driving of the vibration motor 43 in the final cycle (here, the sixth cycle) is completed. Further, it is not necessary to continuously rotate the developing roller 31 and the toner supply roller 30 for a predetermined time. Therefore, the execution time of the toner recovery mode can be shortened.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, the shape and configuration of the toner receiving support member 35 and the toner receiving member 37 shown in the above embodiment are merely examples, and are not particularly limited to the above embodiment, and these are appropriately set according to the apparatus configuration and the like. be able to.

  In the above-described embodiment, the present invention uses a two-component developer, forms a magnetic brush on the toner supply roller 30, moves only the toner from the toner supply roller 30 to the development roller 31, and performs photosensitivity from the development roller 31. Although the present invention is applied to the developing devices 3a to 3d for supplying toner to the body drums 1a to 1d, as shown in FIG. 14, the development roller 31 and the toner supply roller 30 are arranged opposite to those in the above embodiment. Toner is supplied to the photosensitive drums 1a to 1d by a magnetic brush made of a two-component developer held on the surface of a roller 31 (in this configuration, a magnetic roller having the same configuration as the toner supply roller 30 of the above embodiment). The toner supply roller 30 is held on the surface of the toner supply roller 30 (in this configuration, the same configuration as the developing roller 31 of the above embodiment). That supplies to the developing roller 31 the toner, in the developing device to recover the excess toner in the developing roller 31 surface with a toner supply roller 30 can be applied. Even in this configuration, it is possible to effectively suppress the toner dropped from the developing roller 31 from being accumulated around the regulating blade 33 facing the toner supply roller 30. Hereinafter, the effects of the present invention will be described more specifically with reference to examples.

  The relationship between the operation pattern of the vibration motor 43 and the occurrence of toner drop in the toner recovery mode when the charge attenuation level of the toner is changed was investigated. As a test method, the charge attenuation constant α of the toner in the developing devices 3a to 3d is changed in three stages of less than 0.03, 0.03 or more and less than 0.05, and 0.05 or more, and the operation shown in FIG. Pattern 1 (repeated 6 cycles with drive time t2 = 0.6 seconds and stop time t3 = 0.2 seconds during one operation cycle), operation pattern 2 shown in FIG. 13 (drive time t2 = one operation cycle = 11 seconds repeated with 0.6 seconds and stop time t3 = 0.2 seconds) and the operation pattern 3 shown in FIG. 14 (drive time t2 for the first cycle of operation = 0.2 seconds, drive time for the second cycle) t2 = 0.3 seconds, drive time t2 of the third cycle t2 = 0.4 seconds, drive time t2 of the fourth cycle t2 = 0.5 seconds, drive time t6 after the sixth cycle = 0.6 seconds, Toner recovery mode in cycle repetition) Run was visually observed toner off of generation when performing printing immediately. An electrostatic diffusivity measuring device (NS-D100 type, manufactured by Nano Seeds) was used for measuring the charge decay constant α.

  The process speed of the color printer 100 is 25 sheets / minute, the rotational speed of the photosensitive drums 1a to 1d is 210 mm / second, the drum surface potential (bright potential) V0 = + 430V, the image portion potential (dark potential) VL = + 100V, The peripheral speed ratio of the developing roller 31 to the photosensitive drums 1a to 1d is 1.5 (with rotation), the peripheral speed ratio of the toner supply roller 30 to the developing roller 31 is 1.2 (counter rotation), and between the drum and the developing roller The gap was 0.12 mm, and the gap between the developing roller and the toner supply roller was 0.3 mm.

The developing roller 31 is made of alumite-treated surface and laminated with a resin coating layer. The DC component Vslv (DC) = 50 V and the AC component Vslv (AC) (Vpp = 1500 V, frequency 3.7 kHz, duty ratio 27%). ) And a bias in which an AC component Vmag (AC) (Vpp = 2200 V, frequency 4.7 kHz, Duty ratio 68%) is superimposed on the DC component Vmag (DC) = 350 V. Was applied. Further, a positively chargeable toner having an average particle diameter of 6.8 μm was used as the toner, and a coated ferrite carrier having a volume resistivity of 10 ¹⁰ Ωcm, a saturation magnetization of 65 eum / g, and an average particle diameter of 35 μm was used as the carrier.

The toner receiving member 37 was prepared by bonding two stainless steel plates having a thickness of 0.1 mm, and had a length of 317 mm, a width of the toner receiving surface 37b of 12.7 mm, and a thickness of 0.2 mm. The vibration motor 43 uses a motor with a rated rotational speed of 10000 ± 3000 rpm, a rated voltage of 3.0 V (rated voltage range of 2.6 to 3.6 V), a rated current of 160 mA, and a starting current of 175 mA. A weight of a semi-cylindrical tungsten alloy having a semicircular bottom with a corner of 150 ° and a length of 3.6 mm (volume 42.39 mm ³ , mass 0.838 g) was fixed. The results are shown in Table 1.

  As shown in Table 1, in the operation pattern 1 shown in FIG. 12, no toner drop occurred when α <0.03 (Example 1), but when 0.03 ≦ α <0.05. And α> 0.05, toner drop occurred (Comparative Examples 1 and 2).

  Further, in the operation pattern 2 shown in FIG. 13, no toner drop occurred when 0.03 ≦ α <0.05 (Example 2), but no toner drop occurred when α> 0.05. (Comparative Example 3). Further, in the operation pattern 3 shown in FIG. 14, no toner drop occurred even when α> 0.05 (Example 3).

  From the above results, when the toner charge attenuation level is increased, the total driving time of the vibration motor 43 in the toner recovery mode is lengthened, and when the toner charge attenuation level is further increased, the vibration motor 43 is operated once. It was confirmed that toner drop can be suppressed by increasing the driving time per step in steps.

  The present invention can be used for an image forming apparatus including a developing device having a toner receiving member facing the developing roller between a region where the image carrier and the developing roller are opposed to each other and a regulating blade. By utilizing the present invention, an image forming apparatus capable of maintaining the recovery performance of toner deposited on a toner receiving member and suppressing image defects due to toner dropping even when the charge attenuation level of toner in a two-component developer changes. Can be provided.

Pa to Pd Image forming section 1a to 1d Photosensitive drum (image carrier)
3a to 3d Developing device 4a to 4d Toner container (toner container)
20 Developer container (casing)
20a Partition wall 30 Toner supply roller 31 Development roller 33 Ear cutting blade (regulating blade)
35 toner receiving support member 35a tip portion 36 support member body 37 toner receiving member 37a bent portion 37b toner receiving surface 37c toner dropping surface 40 vibration generating device (vibration generating means)
41a, 41b Sheet member 42 Motor mounting holder 43 Vibration motor 43a Output shaft 48 Contact spring 50 Excitation weight 57 Reader / writer module (reading module)
58 IC chip (memory means)
90 control unit 100 color printer (image forming apparatus)

Claims (5)

An image carrier on which an electrostatic latent image is formed;
A developing roller that is disposed to face the image carrier and supplies toner to the image carrier in a region facing the image carrier;
A toner supply roller that is disposed to face the developing roller and supplies toner to the developing roller in a region facing the developing roller;
A regulating blade disposed opposite to the toner supply roller at a predetermined interval;
A casing that houses the developing roller, the toner supply roller, and the regulating blade;
A toner receiving support member disposed in the casing and facing the developing roller or the toner supply roller between the regulating blade and the image carrier;
A toner receiving member disposed along the longitudinal direction of the toner receiving support member and having a toner receiving surface for receiving toner falling from the developing roller;
Vibration generating means for vibrating the toner receiving member;
A developing device for developing an electrostatic latent image formed on the image carrier,
A control unit for controlling driving of the developing device;
An image forming apparatus capable of executing a toner recovery mode in which the toner receiving member is vibrated by the vibration generating means during non-image formation to shake off the toner deposited on the toner receiving surface.
In the toner recovery mode, a driving period in which the vibration generating unit is continuously driven for a certain period of time and a stop period in which the driving of the vibration generating unit is stopped for a certain period of time are alternately repeated.
When the charge attenuation constant of the toner in the two-component developer stored in the casing is greater than or equal to a predetermined value, the control unit is configured to reduce the drive period and the stop compared to when the charge attenuation constant is less than the predetermined value. An image forming apparatus characterized by increasing the number of repetitions of a period.   2. The control unit according to claim 1, wherein when the charge decay constant is equal to or greater than a predetermined value, the control unit lengthens the drive period in a stepwise manner over a plurality of times from the start of driving of the vibration generating unit. Image forming apparatus. A toner storage container for storing toner to be supplied to the developing device;
A reading module for reading information stored in a non-volatile storage means mounted on the toner container,
The control unit changes the number of repetitions of the driving period and the stop period or the length of the driving period based on a toner charge decay constant in the storage unit read by the reading module. The image forming apparatus according to claim 1.   4. The image formation according to claim 1, wherein the control unit rotates the developing roller and the toner supply roller in the same direction as during image formation during execution of the toner recovery mode. apparatus.   The controller rotates the developing roller and the toner supply roller in a direction opposite to that at the time of image formation while driving the vibration generating unit, and after the driving of the vibration generating unit is finished, the developing roller and the toner supply roller 4. The image forming apparatus according to claim 1, wherein the image forming apparatus is rotated in the same direction as that during image formation for a predetermined time.

Images