JP2005091715A - Toner supply system and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner supply system for acquiring high-quality image by highly precisely supplying toner to a development device, and also to provide an image forming apparatus. <P>SOLUTION: The toner supply system is provided with: a sub-hopper 61 provided between a toner vessel 80 and the development device 60 and storing the toner supplied to the development device 60 once; upper and lower partitioning members 64 for partitioning the sub-hopper 61 in a gravity direction; an upper chamber 62 and a lower chamber 63 formed in the sub-hopper 61 by the upper and lower partitioning members 64; a powder pump 70 for moving the toner from the toner vessel 80 to the upper chamber 62 of the sub-hopper 61; a toner circulating means provided in the upper chamber 62 of the sub-hopper 61; a lower screw 86 for supplying the toner to the development device 60 provided in the lower chamber 63 of the sub-hopper 61; and a rib 87 for preventing the toner moved from the toner vessel 80 to the sub-hopper 61 from flowing into the development device 60 through the lower chamber 63 without being circulated in the upper chamber 62. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a toner replenishing device and an image forming apparatus for replenishing toner stored in a toner storing means to a developing device that performs visible image processing on an electrostatic latent image formed on an image carrier.

  Conventionally, in image forming apparatuses such as printers, copiers, and facsimile machines, a toner storage container for storing toner such as a toner bottle or a toner cartridge is set in the apparatus main body, and toner is supplied from the container to the developing device. It has been. Most of this type of image forming apparatus supplies toner stored in a toner storage container to the developing device by free fall, or supplies toner to the developing device using mechanical auger means.

  However, the former toner transfer by free fall is greatly restricted by the arrangement relationship between the storage container and the developing device, and the toner transfer amount cannot be controlled. In addition, although the toner transfer by the latter auger means can control the toner transfer amount, the transfer path is almost linearly limited, and if the transfer path is long, the toner agglomerates and the like deteriorates the toner quality. There is a problem to let you do. For this reason, in an apparatus that performs toner transfer by the auger means, the toner storage container must be disposed in the vicinity of the developing device, and the auger means cannot lift the toner at a steep angle even if the transfer distance is short. It was also difficult to dispose the toner storage container below the developing device.

JP 2000-47465 A JP 2000-98721 A JP 2003-131485 A

  Patent Documents 1 and 2 disclose toner transfer devices that can relieve the problems of the conventional image forming apparatus. Such a toner replenishing device is configured to transfer toner by the suction force of the powder pump. Accordingly, the toner storage container can be installed at almost any position without being restricted by the position of the developing device, and a flexible container can be used, so that the container can be easily recovered and the transportation cost does not increase. . Furthermore, since air is supplied into the toner container and the air sufficiently agitates the toner, the toner quality can be maintained in a favorable state.

  In the toner transfer device disclosed in the above-mentioned publication, the powder pump is operated by the signal of the toner concentration sensor, and the toner is replenished. Toner replenishment in this case is very often a case where a small amount of toner is supplied many times, and the powder pump repeatedly operates in a short time.

  However, although the powder pump is suitable for transferring a certain amount of toner, it can be said that it is relatively unsuitable for transferring toner in small amounts with high accuracy. That is, due to the configuration in which the toner is transferred by the negative pressure generated by the powder pump, the discharge amount varies depending on the type of toner and the solid-gas ratio, and therefore it has been difficult to always supply the required small amount of toner with high accuracy. . For this reason, toner density control in the developing device may become unstable, which may affect image density stability. Such a problem causes a change in the toner density to be large for a recent developing apparatus in which a reduction in the size of the developing unit is promoted because the amount of developer stored is small.

  Furthermore, if the powder pump is repeatedly turned on and off in a short time, the powder pump has a high torque at the start of rotation, which accelerates the wear of the rubber stator and shortens the life of the powder pump. It was. Furthermore, in the toner transfer device, since the toner is transferred by the negative pressure of the powder pump, the generation time of the negative pressure is short when replenishing a small amount, and there is a problem that the toner is easily clogged in the toner transfer tube.

  A toner replenishing device that can alleviate this problem is disclosed in Patent Document 3. The toner replenishing device described in this publication is configured so that the toner transferred by the powder pump is temporarily stored in the sub hopper, and the toner stored in the sub hopper is replenished to the developing device according to the consumption amount. Therefore, the weak point of the powder pump is covered by providing the sub hopper, and a stable and long-life toner replenishing device can be provided.

  By the way, in the toner replenishing device using the powder pump, since the path from the toner container to the powder pump is sealed, the sub hopper downstream of the powder pump is likely to generate a pressure increase with toner conveyance. In addition, the toner conveyed by the powder pump has higher fluidity than that of the screw conveyance or the like that is normally used. For this reason, the toner conveyed to the sub hopper by the powder pump flows into the developing device through the toner already stored in the sub hopper, and there is a problem that the toner is excessively replenished and the image quality is deteriorated. there were.

  An object of the present invention is to provide a toner replenishing device and an image forming apparatus that can replenish toner to a developing device with high accuracy and obtain a high-quality image.

  In order to solve the above-described problems, the present invention provides a toner replenishing device that replenishes toner stored in a toner storage unit to a developing device that performs visible image processing on an electrostatic latent image formed on an image carrier. A sub-toner storage unit that is provided between the storage unit and the developing device and temporarily stores toner to be replenished to the developing device; an upper and lower partition member that partitions the sub-toner storage unit in the direction of gravity; and the upper and lower partition members An upper chamber and a lower chamber formed in the sub-toner storage unit, and the toner in the toner storage unit is replenished to the developing device via the upper chamber and the lower chamber of the sub-toner storage unit in order. It is a feature.

The toner replenishing device of the present invention is effective when the upper chamber has a larger floor area than the lower chamber.
Further, the sub-accommodating unit supplies the toner transferred from the toner storing means provided in the upper chamber and the toner in the upper chamber provided in the upper and lower partition members to the lower chamber. It is effective if a supply unit is provided.

  In order to solve the above problems, the present invention provides a toner replenishing device for replenishing toner stored in a toner storage unit to a developing device that performs visible image processing on an electrostatic latent image formed on an image carrier. A sub-toner storage unit that is provided between the toner storage unit and the developing device and temporarily stores toner to be replenished to the developing device, a vertical partition member that partitions the secondary toner storage unit in the direction of gravity, and the vertical partition member An upper chamber and a lower chamber formed in the sub toner storage unit, a toner moving means for moving toner from the toner storage unit to the upper chamber of the sub toner storage unit, and an upper chamber of the sub toner storage unit. The toner circulating means, the toner replenishing means for replenishing toner to the developing device provided in the lower chamber of the sub-toner storage section, and the toner moved from the toner storage section to the sub-toner storage means It is characterized by having a means for preventing flow to prevent the flow into the developing device through the lower chamber without circulation in the chamber.

  The toner replenishing device according to the present invention includes two screws that move the toner in opposite directions to each other, wherein the toner circulating means is disposed in each of a partition plate having both ends opened and a space partitioned by the partition plate. It is effective to be composed of

Furthermore, the toner replenishing device of the present invention is effective when the toner replenishing means is constituted by a single screw.
Furthermore, in the toner replenishing device of the present invention, the toner moving means includes a screw having an elastic member having a spiral groove therein and a rotor that moves the toner in the axial direction by rotating inside the stator. The pump means is effective.

  Furthermore, the toner replenishing device according to the present invention is configured so that the toner sent from the receiving unit to the upper chamber is supplied to the lower chamber after being circulated more than a half of a circulation path by the toner circulation unit. It is effective when the position of the supply unit is set.

Furthermore, the toner replenishing device of the present invention is effective when the toner replenishing means replenishes the developing device with an amount of toner corresponding to the rotation time of the screw.
Furthermore, the toner replenishing device of the present invention is effective when the toner flow preventing means is a rib provided on the lower chamber side of the upper and lower partition members.

Furthermore, the toner replenishing device of the present invention is effective when the leading edge of the rib is formed in a circular arc concentric with the screw provided in the lower chamber.
Furthermore, the toner replenishing device of the present invention is effective when the distance between the leading edge of the rib and the outer diameter of the screw provided in the lower chamber is 1 mm or less.

  Furthermore, in the toner replenishing device of the present invention, it is effective that the toner flow preventing means is an air pressure adjusting unit provided between the toner replenishing path from the outlet of the toner moving means to the developing device inlet. .

Furthermore, in the toner replenishing device of the present invention, it is effective that the air pressure adjusting unit is an opening covered with a filter that releases the internal pressure to the outside air.
Furthermore, the toner replenishing device of the present invention is effective when the opening is provided in the vicinity of the outlet of the toner moving means.

  Furthermore, in the toner replenishing device of the present invention, the toner inflow prevention means does not drive one screw provided in the lower chamber of the sub toner storage means while the toner moving means is being driven. Control is effective.

According to the configuration of the first aspect, the toner replenishment path of the sub toner storage portion can be made long.
According to the configuration of the second and third aspects, in addition to the above effects, highly accurate toner supply can be obtained.

  According to the fourth aspect of the present invention, it is possible to prevent the toner moved from the toner storage portion to the sub toner storage means from flowing into the developing device via the lower chamber without circulating in the upper chamber.

According to the configuration of the fifth to eighth aspects, it is possible to suppress the occurrence of toner inflow by lengthening the toner replenishment path of the sub toner storage portion.
According to the configuration of the seventh aspect, it is possible to lengthen the toner replenishment path of the sub toner storage means and suppress the occurrence of toner flow.

According to the configuration of the twelfth to fourteenth aspects, it is possible to prevent the toner from flowing into the developing device with a simple configuration of providing the rib.
According to the configurations of the fifteenth to seventeenth aspects, it is possible to prevent the toner from flowing into the developing device with a simple configuration in which the atmospheric pressure adjusting unit is provided.

  According to the configuration of the eighteenth aspect, the toner developing device can be connected to the toner developing device with a simple configuration in which the driving of the single screw provided in the lower chamber of the sub toner storage unit is not performed during the driving of the toner moving unit. Inflow can be prevented.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic view showing a color copying machine as an example of an image forming apparatus according to the present invention. In this color copying machine, a copying machine main body 100 is arranged at the center, and a sheet feeding unit 200 configured in a table shape is arranged below the copying machine main body 100. It is the composition which arranged.

  The copying machine main body 100 is provided with an intermediate transfer belt 10 as an image carrier constituted by a flexible endless belt wound around a plurality of rollers 14, 15, 16. In the intermediate transfer belt 10, one of the plurality of rollers 14, 15, 16 is rotationally driven by a driving device (not shown), whereby the intermediate transfer belt 10 is driven to run in the clockwise direction indicated by an arrow, and the other The roller rotates. Black, cyan, magenta, and yellow image forming units 18 are arranged side by side on the upper traveling side of the intermediate transfer belt 10 that travels in this way. That is, the tandem image forming apparatus 20 is configured by arranging four image forming means 18 on the running side between the roller 14 and the roller 15.

  The four image forming units 18 include a photosensitive drum 40 as a latent image carrier in contact with the intermediate transfer belt 10. Around the photosensitive drum 40, a charging device, a developing device, a cleaning device, a static eliminator, and the like are disposed. Further, a transfer device is disposed inside the intermediate transfer belt 10 at a position where the photosensitive drum 40 contacts the intermediate transfer belt 10. 62 is provided. In the present embodiment, the four image forming units 8 have the same structure, but the color of the toner of the developing device is divided into four colors of black, cyan, magenta, and yellow. Further, an exposure device 21 for irradiating the surface of each photosensitive drum with light-modulated laser light is disposed above each image forming unit 18, and this laser light is applied to the photosensitive drum between the charging device and the developing device. To do. Although the exposure apparatus 21 may be provided for each image forming unit 18, using the common exposure apparatus 21 is advantageous in terms of cost.

  On the other hand, a secondary transfer device 22 is provided on the opposite side of the intermediate transfer belt 10 from the tandem image forming device 20. The secondary transfer device 22 is arranged so that a secondary transfer belt 24, which is an endless belt, is wound between rollers 23, and the belt is pressed against the roller 16 via the intermediate transfer belt 10.

  In FIG. 1, a fixing device 25 for fixing a transfer image carried on a sheet is provided on the left side of the secondary transfer device 22. The fixing device 25 of this embodiment includes a pressure roller 27 and a fixing belt 26 that is an endless belt pressed against the pressure roller 27.

  The secondary transfer device 22 described above is also provided with a sheet transport function for transporting the image-transferred sheet to the fixing device 25. Of course, a non-contact charger may be disposed as the secondary transfer device 22. In such a case, it is necessary to separately provide a sheet conveying device for conveying the transferred sheet to the fixing device 25.

  In the illustrated example, a sheet reversing device 28 for reversing the sheet so as to record images on both sides of the sheet is provided below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming device 20 described above. It has.

  Now, when making a copy using a color copying machine having such a configuration, a document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed by it.

  When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. When this happens, the scanner 300 is immediately driven to travel on the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

  Further, when a start switch (not shown) is pressed, the intermediate transfer belt 10 is rotated, and at the same time, the photosensitive member 40 is rotated by the individual image forming means 18 so that the black, yellow, A magenta / cyan monochrome image is formed. Then, as the intermediate transfer belt 10 travels, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.

  On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed unit 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller The sheet is separated one by one at 45 and put into the sheet feeding path 46, conveyed by the conveying roller 47, guided to the sheet feeding path 48 in the copying machine main body 100, abutted against the registration roller 49 and stopped.

  Alternatively, when manual feeding is selected, the sheet feeding roller 50 is rotated to feed out the sheets on the manual tray 51, separated one by one by the separation roller 52, and put into the manual feeding path 53. Stop by hitting.

  Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. Full color images are recorded on the sheet at once.

  The image-transferred sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to fix the transferred image. Are discharged and stacked on the discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.

  On the other hand, the intermediate transfer belt 10 after image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 10 after image transfer, and is prepared for re-image formation by the tandem image forming apparatus 20.

FIG. 2 is a configuration diagram of a toner supply mechanism for supplying toner to the developing device of the image forming unit 18.
In FIG. 2, a toner container 80 serving as a toner storage unit that stores toner to be replenished to the developing device 60 is set in a set unit (not shown) provided in the copying machine main body 100. In this setting portion, a nozzle 90 to be inserted into the toner container 80 is provided in a machine frame (not shown), and when the toner container 80 is set in the setting portion, the shutter 81 is pushed out to the side, and the nozzle 90 is inserted. The nozzle 90 has a single tube structure, and a toner transfer tube 59 is connected to the end opposite to the insertion side of the nozzle 90.

  The toner container 80 is a flexible and deformable bag-like body, and the bag portion has a single-layer or multi-layer configuration of a flexible sheet material (thickness of about 80 to 125 μm) such as a polyester film or a polyethylene film. It is a container-shaped powder. The toner container 80 is provided with a toner discharge hole 83 in the lower center thereof, and a base member 82 made of resin such as polyethylene or nylon is fixed. The toner discharge hole 83 of the base member 82 is normally closed by the shutter 81. However, when the toner container 80 is set in the setting portion, the shutter 81 is pushed out to the side by the nozzle 90, and the opening of the nozzle 90. The toner discharge hole 83 communicates. Reference numeral 91 denotes a spring for returning the shutter 81, which is used to return the toner container 80 to a position where the toner discharge hole 83 is closed when the toner container 80 is removed from the set portion.

  On the other hand, the developing device 60 is provided with a sub hopper 61 as an auxiliary toner storage means at the top thereof, and the toner in the toner container 80 is temporarily stored in the sub hopper 61. On the sub hopper 61, a powder pump 70 is provided as a toner moving means for moving the toner in the toner container 80 to the sub hopper 61. This powder pump 70 is a uniaxial eccentric screw pump, and is made of a rotor 71 made of a screw shape eccentric with a material having rigidity such as metal, and an elastic body such as rubber, and is a double screw shape. And a holder 73 made of a resin material or the like that wraps these and forms a powder conveyance path. In the rotor 71, a gear 75 (shown in FIG. 3) integrally connected to a drive shaft 74 connected by a pin joint is drivingly connected to a first clutch 76 via an idle gear (not shown). The operation of the powder pump 70 is controlled by turning on / off 76. The first clutch 76 and a second clutch 68 described later are provided on a rotary drive shaft 79 that is driven by a drive device (not shown).

  A toner suction part 77 is provided at the tip of the holder 73, that is, the right end in FIG. 2, and the toner transfer tube 59 is connected to the toner suction part 77. As the toner transfer tube 59, for example, a flexible tube having a diameter of 4 to 10 mm and made of a rubber material having excellent toner resistance (for example, polyurethane, nitrile, EPDM, silicon, etc.) is extremely used. An effective and flexible tube can be easily piped up and down, left and right. If the powder pump 70 described above is used, the toner in the toner container 80 can be smoothly conveyed even when the toner discharge port of the toner storage means is at a lower position in the vertical direction than the toner receiving port of the sub hopper 61. it can. As shown in FIGS. 2 and 3, the sub-popper 61 is formed in a substantially inverted triangular shape in its longitudinal cross section, and the inside thereof is divided in the direction of gravity by an upper and lower partition member 64 to provide an upper chamber 62 and a lower chamber 63. It has been. The upper chamber 62 having a floor area larger than that of the lower chamber 63 is provided with a pair of upper screws 84 and 85 that are driven to rotate in opposite directions, and a partition plate 66 that is disposed between both screws and is open at both ends. Yes. Although the partition plate 66 is formed integrally with the upper and lower partition members 64, both members may be configured as separate members.

  As shown in FIG. 4, the upper chamber 62 configured as described above has a position indicated by symbol A as a supply position of the toner conveyed by the powder pump 70, and the toner supplied to the position A is the upper screw 84. , 85 are circulated in the direction of arrow P1, that is, counterclockwise. Reference symbol B is a communication hole between the upper chamber 62 and the lower chamber 63, and the toner circulating in the direction of the arrow P <b> 1 by the upper screws 84 and 85 falls from the communication hole B to the lower chamber 63. Further, as shown in FIG. 5, the lower chamber 63 is provided with a lower screw 86, and the toner supplied to the position B ′ through the communication hole B is moved in the direction of the arrow P <b> 2 by the rotation of the lower screw 86. Reference numeral C is a replenishing port for communicating the lower chamber 63 and the developing device 60. The toner moved in the direction of the arrow P2 drops from the replenishing port C into the developing device 60 and is replenished.

  The sub hopper 61 configured as described above temporarily stores the toner supplied by the powder pump 70 and is transferred to the developing device 60 by a screw. The upper screws 84 and 85 and the lower screw 86 are drivingly connected to the second clutch 88 provided on the rotary drive shaft 79 via the idle gear train 87, with the gears 84a, 85a and 86a of the respective screws being connected to the second clutch. The on / off of the drive is controlled by 88. The upper screws 84 and 85 and the lower screw 86 are set so that the toner conveyance amount of the upper screws 84 and 85 is larger than that of the lower screw 86 by, for example, different screw diameters and rotational speeds. Accordingly, since the upper screws 84 and 85 and the lower screw 86 of this example are driven simultaneously, the lower chamber 63 is normally almost full of toner, and the toner in the upper chamber 62 circulates in the direction of the arrow P1, When the toner is replenished, the corresponding toner falls from the communication hole B to the lower chamber 63. The driving of the upper screws 84 and 85 and the lower screw 86 can be controlled separately.

  Further, the sub hopper 61 is provided with a toner sensor 69 as toner detecting means for detecting the presence or absence of toner on the side wall in the vicinity of the upstream side in the toner circulation direction of the position A to which the toner transferred by the powder pump 70 is supplied. The toner sensor of this example is a vibration type sensor, and detects the presence or absence of toner on a toner sensor detection surface 69a that contacts the toner in the upper chamber 63.

  In the toner replenishing device configured as described above, when a toner replenishing command is issued to the developing device 60, the second clutch 68 is turned on to operate the upper screws 84 and 85 and the lower screw 86. An amount of toner corresponding to the rotation time of the lower screw 86 is supplied to the developing device 60. On the other hand, in the toner replenishment from the toner container 80 to the sub hopper 61, the toner sensor 69 monitors the toner in the hopper upper chamber 62. When the toner decreases from the detection position of the sensor, the powder pump 70 is activated. The toner in the toner container 80 is supplied into the sub hopper 61. At this time, it is not necessary to control the toner replenishment amount to the sub hopper 61 with high accuracy, and therefore, the toner transfer amount by the powder pump 70 is set to be larger than the amount replenished to the developing device 60 by the lower screw. .

  In addition, if the detected amount of toner in the toner sensor 69 remains below a specified amount even after the powder pump 70 is operated several times, it is determined that the toner in the toner container 80 is almost out of toner. When it is determined that the toner near end is reached, a predetermined operation, for example, indicating that the cartridge is replaced with an operation panel (not shown) is displayed, and image formation is stopped after a predetermined number of image formations. Further, when the toner near end is detected, the sub hopper 61 does not have any toner, so the toner density of the developing device 60 does not decrease, and therefore the image density does not become unstable when the toner near end is detected.

  In order to enjoy such an effect, the toner sensor 69 is preferably arranged in the vicinity of the upstream of the position A where the toner is replenished by the powder pump 70. A toner circulation path is formed so that the maximum amount of toner can be stored using the internal space. Accordingly, the upper screw 62, 85 has a gap of more than half a circumference of the path through which the toner circulates from the position A where the toner is replenished by the powder pump 70 in the upper chamber 62 to the communication hole B which supplies the toner to the lower chamber 63. When the amount of toner is low, the toner from the toner container 80 does not immediately fall into the lower chamber 63, and toner supply to the developing device can be continued to some extent even if it is determined that the toner is near the end. Accordingly, it is possible to surely prevent the occurrence of a recorded matter having a lowered image quality due to a change in image density, which often occurs at the time of toner near-end.

  Incidentally, in the toner replenishing device shown in FIG. 2, there has been a phenomenon in which the toner replenishment to the developing device 60 becomes excessive, and the toner density of the developing device 60 increases and a high-quality image cannot be obtained. Therefore, the inventor of the present application investigated in detail the cause of the phenomenon.

  As a result, the toner transported by the powder pump 70 has higher fluidity than the screw transport toner that is normally used, and in the toner transport using the powder pump 70, the toner transport path from the toner container 80 to the screw pump. It has been found that this is because the pressure rises with toner conveyance in the sub hopper 61 downstream of the screw pump. Further, it has been found that the above phenomenon occurs when the powder pump 70 operates the conveying and the upper and lower screws 84, 85, 86 simultaneously. Further, when the movement of the toner during the above phenomenon was examined, the toner conveyed to the sub hopper 61 by the powder pump 70 flows back in the upper chamber 62 against the toner circulation as if water flows, that is, from the replenishment position A to the shortest. It has been found that it flows in the direction of the communication hole B at a distance, and further flows into the developing device 60 through a gap formed between the upper surface of the toner and the lower surface of the upper and lower partition members 64 in the lower chamber 63. In order to suppress the occurrence of the toner backflow phenomenon, the supply unit B is set so as to be separated from the receiving unit A and not on the same screw, but only the positional relationship between the receiving unit A and the supplying unit B is set. However, the toner backflow phenomenon could not be eliminated.

  Therefore, the toner replenishing device is provided with a flow preventing means for preventing the toner from flowing into the developing device 60.

  FIG. 6 is a cross-sectional explanatory view of the sub hopper 61 showing the first embodiment of the present invention. In this embodiment, the toner flowing out to the developing device 60 is interposed between the toner upper surface of the lower chamber 63 and the lower surface of the upper and lower partition members 64. A rib 87 for stopping the flow of toner is provided in the lower chamber 63 as a flow-in prevention means because it passes through the formed gap. The ends of the ribs 87 are formed substantially concentrically with the axis of the lower screw 86, and are configured to make the gap g between the lower screw 86 and the outer periphery as small as possible. When the gap g was 1 mm or less, the toner flow was stopped and it was effective. The rib 87 is made of a thin plate, and even one sheet is effective. However, it is more effective to provide a plurality of ribs with appropriate intervals. Further, even if the lower surface of the upper and lower partition members 64 has the same shape at the end of the ribs over the entire length instead of the ribs 87, it is effective in preventing the inflow. However, with this configuration, the toner storage capacity of the lower chamber 63 is reduced. Therefore, it is inferior to the rib 87 in that respect.

  The toner flowing out to the developing device 60 is also caused by the increase in pressure in the sub hopper 61 downstream of the pump due to the toner conveyance using the powder pump (screw pump) 70, so that the inflow prevention means Between the toner supply path from the outlet of the powder pump 70 to the inlet of the developing device 60, that is, the supply port C, in this embodiment, as shown in FIG. 2, an air pressure adjusting unit as an opening 88 provided in the vicinity of the outlet of the powder pump 70. It consists of At this time, the rising pressure in the sub hopper 61 by the powder pump 70 is very small. However, when the pressure is released by the opening 88, the toner does not flow in and is effective. However, the opening 88 is preferably provided on the upper surface in the direction of gravity in order to prevent scattering of the toner. To satisfy this condition, the opening 88 is the upper surface near the outlet of the powder pump 70 in the example of FIG. Further, the opening 88 is preferably closed with a filter (not shown) to prevent toner scattering. A filter with a coarser mesh is effective because the pressure to be released is smaller, and the problem of toner scattering does not occur even if the filter is used roughly the same as or slightly coarser than the toner particles.

  FIG. 7 is an example of control of the toner replenishing device, and shows that a repeat image is being formed. While the repeat image is being formed, the write signal is continuously turned on. For this reason, the toner concentration in the developer in the developing device 60 is lowered, and a rotation time that satisfies the required toner amount is set based on the detection result, and the second clutch 68 is controlled to be turned on. In the illustrated example, at the time of the second image formation, the detection result of the toner sensor 69 installed in the sub hopper 61 starts to indicate an L state (the toner amount is less than a specified value). Based on the detection result, after the toner sensor signal becomes L for a predetermined number of times (time), the first clutch 76 is turned on for a predetermined time, and the powder pump 70 is driven to supply a predetermined amount of toner. Supply to the sub hopper 61 at a stretch. Here, if the output of the toner sensor 69 does not become H even after a predetermined time has elapsed since the start of the driving of the first clutch 76, this indicates that the toner supply from the toner container 80 is insufficient, and the main body control unit It is determined that the toner near end is detected.

  At this toner replenishment timing, if the powder pump 70 and the upper and lower screws 84, 85, 86 are operated at the same time, toner flows in. Therefore, as shown in FIG. Control is performed so that the operations of the upper and lower screws 84, 85, 86 do not overlap.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said embodiment, Various modifications can be carried out.
For example, the toner detection means provided in the sub hopper 61 is not limited to the vibration type but may be a transmission type sensor. The sub hopper 61 may be a hopper that is not divided into upper and lower chambers.

1 is a schematic view showing a color copying machine as an example of an image forming apparatus according to the present invention. 1 is a configuration diagram illustrating a toner replenishing device of an image forming apparatus of the present invention. 3 is an external perspective view of a toner replenishing unit. FIG. It is explanatory drawing of the upper chamber of a sub hopper. It is explanatory drawing of the lower chamber of a sub hopper. 2 is a cross-sectional explanatory view of a sub hopper showing Embodiment 1. FIG. 10 is a timing chart illustrating a control example of Embodiment 3.

Explanation of symbols

60 Developing Device 61 Sub Hopper 62 Upper Chamber 63 Lower Chamber 69 Toner Sensor 70 Powder Pump 80 Toner Container 84, 85 Upper Screw 86 Lower Screw 87 Rib 88 Opening

Claims (19)

In a toner replenishing device for replenishing toner stored in a toner storage unit to a developing device that performs visible image processing on an electrostatic latent image formed on an image carrier,
A sub-toner storage unit that is provided between the toner storage unit and the developing device and temporarily stores toner to be replenished to the developing device, a vertical partition member that partitions the secondary toner storage unit in the direction of gravity, and the vertical partition member And an upper chamber and a lower chamber formed in the sub toner storage portion, and the toner in the toner storage portion is replenished to the developing device via the upper chamber and the lower chamber of the sub toner storage portion in order. A toner replenishing device.   The toner replenishing device according to claim 1, wherein the upper chamber has a larger floor area than the lower chamber.   2. The toner replenishing device according to claim 1, wherein the sub-accommodating portion includes a receiving portion that receives toner moved from the toner accommodating means provided in the upper chamber, and the upper chamber provided in the upper and lower partition members. And a supply unit for supplying the toner to the lower chamber. In a toner replenishing device for replenishing toner stored in a toner storage unit to a developing device that performs visible image processing on an electrostatic latent image formed on an image carrier,
A sub-toner storage unit that is provided between the toner storage unit and the developing device and temporarily stores toner to be replenished to the developing device, a vertical partition member that partitions the secondary toner storage unit in the direction of gravity, and the vertical partition member An upper chamber and a lower chamber formed in the sub toner storage unit, a toner moving means for moving toner from the toner storage unit to the upper chamber of the sub toner storage unit, and an upper chamber of the sub toner storage unit. The toner circulating means, the toner replenishing means for replenishing toner to the developing device provided in the lower chamber of the sub-toner storage section, and the toner moved from the toner storage section to the sub-toner storage means And a flow preventing means for preventing the toner from flowing into the developing device through the lower chamber without circulation.   5. The toner replenishing device according to claim 4, wherein the upper chamber has a larger floor area than the lower chamber.   5. The toner replenishing device according to claim 4, wherein the sub-accommodating portion includes a receiving portion that receives toner moved from the toner accommodating means provided in the upper chamber, and the upper chamber provided in the upper and lower partition members. And a supply unit for supplying the toner to the lower chamber.   5. The toner replenishing device according to claim 4, wherein the toner circulating means is disposed in each of a partition plate having both ends opened and a space partitioned by the partition plate, and moves toner in opposite directions. A toner replenishing device comprising a screw.   5. The toner replenishing device according to claim 4, wherein the toner replenishing means is constituted by a single screw.   5. The toner replenishing device according to claim 4, wherein the toner moving means includes a stator of an elastic member having a spiral groove therein, and a rotor that moves toner in an axial direction by rotating inside the stator. A toner replenishing device which is a pump means.   The toner replenishing device according to claim 6, wherein the toner sent from the receiving unit to the upper chamber is supplied to the lower chamber after being circulated more than a half of a circulation path by the toner circulation unit. A toner replenishing device in which a position of a supply unit is set.   9. The toner replenishing device according to claim 8, wherein the toner replenishing unit replenishes the developing device with an amount of toner corresponding to a rotation time of the screw. 5. The toner replenishing device according to claim 4, wherein the toner flow preventing means is a rib provided on a lower chamber side of the upper and lower partition members. 13. The toner replenishing device according to claim 12, wherein a leading edge of the rib is formed in an arc concentric with a screw provided in the lower chamber. 13. The toner replenishing device according to claim 12, wherein a distance between a leading edge of the rib and an outer diameter of a screw provided in the lower chamber is 1 mm or less. 5. The toner replenishing device according to claim 4, wherein the toner flow preventing means is an air pressure adjusting portion provided between a toner replenishing path from an outlet of the toner moving means to an inlet of the developing device. Replenishment device. The toner replenishing device according to claim 15, wherein the air pressure adjusting unit is an opening covered with a filter that allows internal pressure to escape to outside air. The toner replenishing device according to claim 16, wherein the opening is provided in the vicinity of an outlet of the toner moving unit. 5. The toner replenishing device according to claim 4, wherein the toner inflow prevention means does not drive a single screw provided in a lower chamber of the sub toner storage means while the toner moving means is being driven. A toner replenishing device, characterized by being controlled. An image forming apparatus using the toner replenishing device according to claim 1.

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