JP2017122834A - Powder conveying device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder conveying device that can accurately perform powder detection with powder amount detection means, and an image forming apparatus.SOLUTION: In a powder conveying device 190 comprising: a powder pump 30 for mixing a powder with a gas and conveying a resulting mixture; a first powder retention part 20 that temporarily retains the powder; and powder amount detection means 22 that is provided inside the first powder retention part and detects the amount of powder inside the first powder retention part, a second powder retention part 80 that temporarily retains a powder conveyed by the powder pump is provided between the powder pump and the first powder retention part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a powder conveying apparatus and an image forming apparatus.

  2. Description of the Related Art Conventionally, powder conveying apparatuses that convey powder using a pump are known.

  Japanese Patent Application Laid-Open No. 2004-228688 discloses a powder conveying apparatus that supplies toner to a sub hopper that is a toner storage unit using a powder pump from a toner container that stores toner that is powder, and develops the toner through the sub hopper. An apparatus for conveying toner to an apparatus is described. A toner end sensor is provided in the sub hopper for detecting the presence or absence of toner in the sub hopper by the pressure exerted on the detection surface by the toner.

  The position of the toner end sensor provided in the sub hopper is preferably located at a position farther downstream in the developer transport direction than the toner discharge port of the powder pump. This is because the toner is discharged while spreading together with air from the toner discharge port of the powder pump into the sub hopper, so that the bulk density of the toner tends to become unstable in the vicinity of the toner discharge port. This is because the bulk density of the toner is stable at a distant position. However, if the toner end sensor is separated from the toner discharge port, toner detection can be performed with high accuracy during a toner recovery operation in which toner is supplied to the sub hopper while driving of the conveying screw provided in the sub hopper is stopped. There can be problems such as

  In order to solve the above problems, the present invention provides a powder pump for transporting powder mixed with gas, a first powder storage section for temporarily storing powder, and the first powder. In a powder conveyance device provided with a powder amount detection means for detecting the amount of powder in the first powder storage unit provided in the storage unit, between the powder pump and the first powder storage unit The second powder storage unit is provided for temporarily storing the powder conveyed by the powder pump.

  As described above, according to the present invention, there is an excellent effect that powder detection can be performed with high accuracy by the powder amount detection means.

FIG. 2 is a schematic configuration diagram of a developing unit. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 4 is a schematic diagram illustrating toner conveyance in a developing unit. (A) The perspective view of a sub hopper, (b) The top view which looked at the sub hopper from the upper part. The conceptual diagram which shows the conveyance path of the side by which one screw is arrange | positioned among the toner stirring circulation paths of a sub hopper, and the sensor was attached to the side surface. The conceptual diagram which shows the example which the sensor position shifted | deviated to the upstream with respect to the pump discharge port. 4A is a plan view of a toner storage unit in the development unit, FIG. 3B is a side view of the toner storage unit in the development unit, and FIG. 3C is a cross-sectional view of the toner storage unit in the development unit. FIG. 3 is a schematic configuration diagram of a developing unit according to a comparative example. FIG. 6 is a schematic diagram illustrating toner conveyance in a developing unit according to a comparative example. The schematic diagram at the time of providing the screw for conveying a toner in a small sub hopper. FIG. 6 is a schematic diagram when a toner stirring member for stirring toner is provided in a small sub hopper. The figure which shows the arrangement position of the toner end sensor in a sub hopper. FIG. 3 is a schematic diagram of a developer conveying device when a pressure relief hole is provided in a small sub hopper.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, referring to FIG. 2, a schematic configuration of a tandem type intermediate transfer color printer which is an electrophotographic image forming apparatus will be described. The color printer (hereinafter referred to as a printer) 100 includes an apparatus main body 110, a paper feed unit 140, an image forming unit 150, and a paper discharge unit 180. The paper feeding unit 140 is arranged at the lower part of the apparatus main body 110, and has a configuration for feeding the transfer paper S to the upper and lower paper feeding cassettes 121 and 122 and the image forming unit 150 that accommodate the transfer paper S that is a sheet-like recording medium. I have. The image forming unit 150 is disposed at a substantially central portion of the apparatus main body 110 and has a configuration for forming an image. The paper discharge unit 180 is disposed on the upper surface of the apparatus main body 110 and includes a paper discharge roller 138 for discharging the transfer paper S on which an image is formed, a paper discharge tray 181 for stacking the discharged transfer paper S, and the like.

  In the image forming unit 150, an intermediate transfer belt 127 configured by an endless belt as an intermediate transfer member is disposed. Below the intermediate transfer belt 127, four image forming units 2Y, 2M, 2C, and 2K are arranged in order from the upstream side in the rotation direction of the intermediate transfer belt 127. These are image forming units corresponding to yellow, magenta, cyan, and black, and the configuration thereof is the same except that colors used in the image forming process are different. In the following description, each image forming unit is common. Only the reference numerals are shown, and the subscripts representing the toner color are omitted.

  The image forming unit 2 includes a photoconductor 1, a charging unit 8 disposed around the photoconductor 1, a developing unit 9, a primary transfer unit n1 including a primary transfer roller 4, a cleaning unit 3, and the like. The photosensitive member 1 is a drum-shaped rotating member and functions as an image carrier. The charging unit 8 functions as a charging unit, the developing unit 9 functions as a developing unit, the primary transfer unit n1 including the primary transfer roller 4 functions as a primary transfer unit, and the cleaning unit 3 functions as a cleaning unit.

  The developing unit 9 processes a latent image on the photoreceptor 1 with a two-component developer including toner and carrier, and has a developing device as a main part. A well-known image forming process (charging process, exposure process, developing process, primary transfer process, cleaning process) is performed on the photoreceptor 1, and a desired toner image is formed on the photoreceptor 1.

  The photosensitive member 1 is rotationally driven in the clockwise direction in the drawing by the driving means, and is uniformly charged by the charging unit 8 (charging process). Next, an electrostatic latent image is formed on the surface of the photoreceptor 1 by irradiation based on image information of a laser beam emitted from an optical writing unit 111 as an exposure unit disposed below the image forming unit 2. (Exposure process). When the electrostatic latent image reaches a position facing the developing unit 9, the electrostatic latent image is subjected to visible image processing with toner contained in the developer supplied from the developing unit 9 (developing step). The toner image on the photoreceptor 1 subjected to the visible image processing in the development process is transferred onto the intermediate transfer belt 127 in the primary transfer portion n1 formed by the intermediate transfer belt 127 and the primary transfer roller 4 (primary transfer). Process). After the transfer, the surface of the photosensitive member 1 reaches a position facing the cleaning unit 3 and untransferred toner remaining on the photosensitive member 1 is collected (cleaning step). After cleaning, the potential of the surface of the photosensitive member 1 is initialized by a static elimination roller. By going through such steps, a series of image forming processes performed on the photoreceptor 1 is completed. The above-described image forming process is executed at the time of forming a single image of only a monochrome image and at the time of forming a full color image. At the time of forming a full color image, each process is performed in each of the four image forming units 2Y to 2K shown in FIG. Executed. The toner images of the respective colors formed on the respective photoreceptors through the development process are transferred onto the intermediate transfer belt 127 so as to form a color image on the intermediate transfer belt 127.

  The intermediate transfer belt 127 onto which the toner images of the respective colors are transferred in a superimposed manner is formed by sandwiching the intermediate transfer belt 127 between a secondary transfer roller 133 and a secondary transfer counter roller 131 as secondary transfer means. Part n2 is reached. The color toner image formed on the intermediate transfer belt 127 is collectively transferred onto the transfer sheet S conveyed to the position of the secondary transfer portion n2.

  A plurality of transfer sheets S are stacked and stored in sheet feeding cassettes 121 and 122 (the upper and lower transfer sheets S have different sizes) in the sheet feeding unit 140 that conveys the transfer sheet S to the position of the secondary transfer unit n2. Yes. The transfer sheets S on the upper and lower sheet feeding cassettes are separated and fed one by one by the cooperative action of sheet feeding rollers 123 and 124 as sheet feeding means and separation means. The fed transfer sheet S is guided to the roller row and temporarily stopped by the registration roller pair 126. After correcting the oblique deviation and the like, the registration sheet pair 126 conveys the transfer sheet S toward the secondary transfer unit n2 at a predetermined timing. Is done.

  The transfer sheet S on which the color image is transferred at the position of the secondary transfer unit n2 is conveyed to the fixing unit 134. Here, the fixing roller 135 is heated by electromagnetic induction by, for example, the IH coil 137. The toner is dissolved by the heat and clamping pressure of the fixing roller 135 and the pressure roller 136, and the color image transferred on the surface of the transfer paper S is fixed. After the fixing, the transfer sheet S is discharged as an output image onto an output tray 181 formed on the upper surface of the apparatus main body 110 by an output roller 138 constituting an output section and stacked. Thus, a series of image forming processes in the image forming apparatus is completed. In FIG. 2, reference numeral 128 denotes a cleaning device for the intermediate transfer belt 127.

  The image forming apparatus 100 according to the present embodiment has a feature in the developer transport device 190 attached to the developing device 10 constituting the developing unit 9, and the configuration will be described in detail. FIG. 1 is a schematic configuration diagram of the developing unit 9. FIG. 3 is a schematic diagram illustrating toner conveyance in the developing unit 9. Here, the developing device 10 and the replenishing means 160 are connected by the transport (circulation) mechanism PD, and the pump 30, the small sub hopper 80, the sub hopper 20, and the like are arranged in the middle of the transport mechanism PD, and these constitute the developer transport device 190. To do. Hereinafter, the developer in the toner container 70 is referred to as toner.

  The developing device 10 is disposed to face the photoreceptor 1. Inside the developing device 10, a developer G in which toner and carrier are mixed is stored, and the developer G is stirred and circulated by the conveying screws 13a and 13b. The developer G transported by the transport screw 13b is transferred to the surface of the developing roller 12 by magnetic force, and develops the latent image on the photoreceptor 1. The developer G on the developing roller is regulated to a certain height or thickness by the doctor blade 14 before reaching the primary transfer nip.

  When the developing process is executed in the developing device 10, the developer conveying device 190 is driven and toner is supplied. A sub hopper 20 that replenishes toner through a vertical pipe 17 is disposed above the developing device 10, and the toner is temporarily stored in the sub hopper 20. The sub hopper 20 is provided with a pair of conveyance paths constituting a toner agitation circulation path in parallel with each other in the horizontal direction. Screws 21a and 21b are rotatably arranged in these conveyance paths, and circulate and convey the temporarily stored toner. As the screws 21a and 21b are rotated by the driving means, the toner is supplied from the vertical pipe 17 to the developing device 10 by free fall while ensuring the dispersibility of the toner in the sub hopper 20. A toner end sensor 22 is attached to the side surface (hopper side surface) of the sub hopper 20.

  A small sub hopper 80 is connected above the sub hopper 20, and a pump 30 is connected above the small sub hopper 80. The pump 30 includes a pump case 34, a diaphragm 33, a suction valve 32 that opens and closes an inflow port 37, and a discharge valve 31 that opens and closes a discharge port 38. The pump 30 reciprocally displaces the diaphragm 33 by a motor 35 and an eccentric shaft portion 36 directly connected to the motor 35, thereby changing the volume of the pump chamber, which is the internal space, to increase and decrease, and positive pressure and negative pressure are alternately changed according to the volume change. This is a positive displacement pump. The pump 30 is a main part of the developer transport device 190 and can transport toner from an arbitrary place to an arbitrary place. Here, the pump 30 sucks the toner in the toner storage unit 60 every driving cycle, and conveys (discharges) the toner to the small sub hopper 80 downstream of the pump. The small sub hopper 80 provided between the sub hopper 20 and the pump 30 temporarily stores the toner mixed with the gas by the pump 30 and transported the toner to the sub hopper 20 by the screw 81 (discharge). To do.

  FIG. 4A is a perspective view of the sub hopper 20. FIG. 4B is a plan view of the sub hopper 20 as viewed from above. As can be seen from FIG. 4, the sub hopper 20 is surrounded by side walls 20a, 20b extending parallel to the two screws 21a, 21b and bearing walls 20c, 20d provided with bearings for the two screws 21a, 21b. Space. Further, the bottom surface 20e of the sub hopper 20 has two parallel arcuate curved surfaces along the outer shapes of the two screws 21a and 21b. The inside of the sub hopper is partitioned into a first transport path 24 and a second transport path 25 by a partition wall 23 having openings at both ends in the longitudinal direction of the screws 21a and 21b, and the screws 21a and 21b are transported respectively. It is provided in the paths 24 and 25. As the screws 21a and 21b rotate, the toner in the sub hopper is conveyed by the screws 21a and 21b. That is, the toner transported to the end side of the first transport path 24 is delivered to the upstream side of the second transport path 25 in the toner transport direction through the opening 23 a of the partition wall 23. The toner transported to the end side of the second transport path 25 is delivered to the upstream side of the first transport path 24 in the toner transport direction through the opening 23 b of the partition wall 23. By this operation, the toner circulates in the sub hopper 20.

  A discharge port 26 for discharging toner from the second conveyance path 25 to the outside of the conveyance path is provided on the bottom surface on the downstream side of the second conveyance path 25. In this example, the toner discharged from the discharge port 26 is conveyed to the developing device 10 through the vertical pipe 17. On the other hand, the toner discharged from the discharge port 82 of the small sub hopper 80 is discharged to the first transport path 24 from the opening 27 provided in the upper part (ceiling part) of the first transport path 24. The opening 27 is provided above the screw 21 a of the first transport path 24. A toner end sensor 22 is provided on the side wall 20 a constituting the first transport path 24. The toner end sensor 22 is a piezoelectric sensor, and detects the presence of toner when the toner contacts the sensor detection surface and a predetermined pressure is applied.

  Here, the positional relationship between the toner end sensor 22 attached to the side surface of the housing of the sub hopper 20 and the discharge port 82 of the small sub hopper 80 will be described. As shown in FIG. 5, the toner end sensor 22 is disposed at a position perpendicular to the longitudinal direction of the screw 21 a and intersecting with a vertical plane passing through the discharge port 82 of the small sub hopper 80. That is, the toner discharge position of the small sub hopper 80 and the mounting position of the toner end sensor 22 in the sub hopper 20 are substantially coincident with each other on a certain vertical plane. When the toner flows into the sub hopper 20 from the discharge port 82 of the small sub hopper 80, the toner flows while spreading slightly as shown in FIG. The term “substantially coincides” can be understood to refer to such a region where the toner spreads and flows, and the toner end sensor 22 shown in FIG. 6 also includes the discharge port 82 of the small sub hopper 80 and the vertical surface. It can be said that it is “almost identical”. In FIG. 6, for example, the toner is conveyed from left to right, and the discharge port 82 of the small sub hopper 80 is shifted to the upstream side in the toner conveyance direction by the screw 21 with respect to the toner end sensor 22.

  The toner container 70 of the replenishing means 160 is a general cylindrical bottle having a spiral groove provided therein as shown in FIG. 1, and the toner inside is discharged by rotating. A seal member 71 installed at the tip of the toner container 70 is made of an elastic material such as sponge, and is fitted through a holder 61 and a toner storage portion 60 that is a space for temporarily storing toner discharged from the toner container 70. And slide and rotate.

  As shown in FIG. 7, the toner storage unit 60 stores agitators 75 a and 75 b which are a pair of plate-like paddle rotation members arranged in parallel inside the casing 601. The rotation shafts 76 of the agitators 75a and 75b are rotatably supported by the casing 601. A rotation drive source 78 is connected to the rotation shaft 76, and at the same time, the pair of agitators 75a and 75b rotate in the direction of the arrow shown in FIG. The agitators 75a and 75b are formed of resin or metal thin plates, and are integrally coupled (attached) to the resin or metal rotating shaft 76.

  As shown in FIG. 7C, the bottom wall of the casing 601 of the toner storage unit 60 is formed in a conical conical surface 602 that is gently inclined toward the center, and a discharge port 64 is formed at the deepest part in the center. Is formed. The discharge port 64 communicates with the pipe 604 of the transport mechanism PD via a lateral discharge path 603 (see FIG. 1), and the tip of the pipe 604 is connected to the inlet 37 of the pump case 34. As shown in FIGS. 7A and 7B, the rotary shafts 76 to which the agitators 75a and 75b are attached are installed at positions shifted from the discharge port 64 as viewed from above. A storage unit sensor 62 is attached to the side surface of the casing 601.

  Next, the toner supply operation will be described. When the toner in the developing device 10 is consumed by image formation (development process), density detection is performed by a toner density sensor attached to the housing of the developing device 10. When the density falls below the appropriate value, a drive command is issued from the control unit 95 (see FIG. 2) to the motor that is the drive source of the sub hopper 20, the screws 21a and 21b of the sub hopper 20 are driven, and the consumed toner is screwed into the screw 21b. Supply from the side. When the density in the developing device 10 reaches an appropriate value, the screws 21a and 21b are stopped, and the control unit 95 keeps the toner density in the developing device 10 constant.

  On the other hand, when the toner in the sub hopper 20 is supplied to the developing device 10, the decrease is detected by the toner end sensor 22. Then, the control unit 95 operates the pump 30 to suck and convey the toner from the toner storage unit 60 and replenish the sub hopper 20 via the small sub hopper 80. When the toner in the toner storage unit 60 is sent to the sub hopper 20 via the small sub hopper 80, the toner decrease in the toner storage unit 60 is detected by the storage unit sensor 62, and the control unit 95 rotates the toner container 70. The toner is stored in the toner storage unit 60. The toner end sensor 22 and the storage unit sensor 62 are piezoelectric level sensors that detect the absence of toner when the toner powder level in the sub hopper 20 and the casing 601 falls.

  FIG. 8 is a schematic configuration diagram of the developing unit 9 according to the comparative example. FIG. 9 is a schematic diagram of toner conveyance in the developing unit 9 according to the comparative example. In the developer conveyance device 190 according to the comparative example shown in FIG. 8, the small sub hopper 80 is not provided between the pump 30 and the sub hopper 20. Therefore, as shown in FIG. 9, the toner mixed with the gas and conveyed from the discharge port 38 of the pump 30 to the sub hopper 20 is directly discharged by the pump operation.

  In such a configuration, toner is continuously discharged from the discharge port 38 by the discharge force of the pump 30 during the operation of the pump 30 immediately below the discharge port 38 of the pump 30 in the sub hopper 20. Is not stable at all. Therefore, when the developer transport device 190 according to the comparative example is used, the toner has a very low bulk density despite the presence of toner on the detection surface of the toner end sensor 22 immediately after transport. There is a possibility that the presence of toner on the detection surface cannot be detected. This is because the toner end sensor 22 detects the presence or absence of toner by applying a certain load to the detection surface, so that the toner fluidity is high and the toner bulk density is too low (the space ratio is high). This is because no load is applied and it is determined that there is no toner.

  On the other hand, unless it is directly under the discharge port 38 of the pump 30, the influence of the discharge force of the pump 30 is small, and the bulk density of the toner is relatively stable. Further, as long as the toner is transported by a transporting member such as a screw and the toner falls by its own weight, the bulk density of the toner at the dropped location is relatively stable.

  In the developer transport device 190 according to the present embodiment, the small sub hopper 80 is provided between the pump 30 and the sub hopper 20, so that the gas is mixed with the gas by the pump 30 and transported into the small sub hopper 80 as shown in FIG. 10. The toner thus transferred is conveyed through the small sub hopper 80 to the discharge port 82 by the screw 81. Since the toner falls from its discharge port 82 by its own weight and is supplied into the sub hopper 20, the bulk density of the toner in the sub hopper 20 can be stabilized. Further, by disposing the toner end sensor 22 away from the discharge port 38 of the pump 30, the influence of the discharge force of the pump 30 on the toner existing on the detection surface of the toner end sensor 22 can be suppressed, and the detection surface. The bulk density of the toner present in the toner can be stabilized. As described above, in the developer transport device 190 according to the present embodiment, the toner bulk density can be stabilized in the small sub hopper 80. Therefore, the configuration of the developer transport device 190 according to the comparative example can stabilize the toner bulk density. Therefore, the intermittent operation of the pump 30 that must be performed is not necessary. Therefore, in the developer transport device 190 according to the present embodiment, since the pump 30 can be continuously driven, the toner transport capability of the pump 30 can be maximized. The toner replenishment amount can be improved as compared with the intermittent operation.

  Further, in the developer transport device 190 according to the present embodiment, the drive of the screw 81 provided in the small sub hopper 80 and the pump 30 is completely synchronized. When the toner end sensor 22 provided in the sub hopper 20 detects “no toner”, the screw 81 and the pump 30 of the small sub hopper 80 are turned on, and the toner end sensor 22 continues until “toner exists” is detected. Drive. As a result, the toner conveyed into the small sub hopper 80 by the pump 30 is conveyed toward the sub hopper 20 by the screw 81, and the toner can be prevented from staying in the small sub hopper 80, and the toner can be stably supplied to the sub hopper 20. Can be supplied. As shown in FIG. 11, a toner agitating member 82 such as an agitator that is a paddle rotating member may be provided in the small sub hopper 80, thereby loosening the toner and ensuring fluidity. Further, the toner stirring member 82 and the pump 30 may be driven in synchronization.

  In the case where the small sub hopper 80 is not provided between the pump 30 and the sub hopper 20 as in the developer conveying device 190 according to the comparative example shown in FIG. 8, the position of the toner end sensor 22 is set to the discharge of the pump 30. It was necessary to shift to the downstream side in the developer transport direction from the discharge port 38, not below the vertical plane passing through the outlet 38. This is because when the toner flows into the sub hopper 20 from the discharge port 38 of the pump 30, the toner flows while spreading together with the gas. For this reason, since the bulk density of the toner becomes more stable as it is farther from the discharge port 38 of the pump 30, the toner end sensor 22 is disposed where the bulk density of the toner is stabilized, thereby avoiding erroneous detection of the toner end sensor 22. This is because it becomes possible.

  Here, if the state of “no toner” detected by the toner end sensor 22 continues for a certain period of time, it is determined that the toner container is empty, the toner container is replaced with a new toner container, and then a toner recovery operation for supplying toner to the sub hopper 20 is performed. Is called. In the toner recovery operation, the image forming operation and the driving of the sub hopper 20 are stopped, and only the pump 30 in the developer transport device 190 and the drive system upstream of the pump 30 in the developer transport direction are driven. When the sensor 22 detects that “toner is present”, the drive system is stopped. The reason why the driving of the sub hopper 20 is stopped in the toner recovery operation is that excessive toner is not supplied from the sub hopper 20 to the developing device 10. In this toner recovery operation, as described above, when the toner end sensor 22 is located away from the discharge port 38 of the pump 30 in the sub hopper 20, the driving of the sub hopper 20 is stopped. The toner must reach the position of the toner end sensor 22 only by the momentum when the toner is discharged. For this reason, the way in which the toner reaches the position of the toner end sensor 22 varies, and the toner recovery failure of the sub hopper 20 (failure of the toner recovery operation due to the fact that the toner end sensor 22 cannot detect the toner for a certain period of time) occurs. Can do.

  In contrast, in the developer transport device 190 according to the present embodiment, a small sub hopper 80 is provided between the pump 30 and the sub hopper 20, and the toner is transported to the sub hopper 20 via the small sub hopper 80. In addition, as shown in FIG. 12, the toner end sensor 22 is installed at a position in the sub hopper 20 that substantially coincides with the vertical plane passing through the discharge port 82 of the small sub hopper 80. During the toner recovery operation, the image forming operation and the driving of the sub hopper 20 are stopped, and the screw 81 and the pump 30 provided in the small sub hopper 80 are driven. As a result, the toner conveyed into the small sub hopper 80 by the pump 30 is conveyed toward the sub hopper 20 by the screw 81 and can be dropped by its own weight to reach the position of the toner end sensor 22 in the sub hopper 20. As a result, the toner recovery operation of the sub hopper 20 can be performed while suppressing excessive toner supply from the sub hopper 20 to the developing device 10.

  In the developer transport device 190 according to the comparative example, in order to improve the amount of toner replenished by the pump 30, the pump 30 must be enlarged, the diaphragm 33 can be increased in stroke, and the rotational speed can be increased. This may cause a problem that noise and vibration increase. For this reason, in the developer conveyance device 190 according to the present embodiment, there is a great effect that the amount of toner replenishment by the pump 30 can be improved without the risk of the occurrence of the problem.

  FIG. 13 is a schematic diagram of the developer conveying device 190 when the small sub hopper 80 is provided with a pressure release hole 83 for performing pressure release in the small sub hopper 80. In the developer conveying device 190 shown in FIG. 13, a pressure release hole 83 is provided in the small sub hopper 80 for pressure release of the gas sent together with the toner from the discharge port 38 of the pump 30 into the small sub hopper 80. Yes. The pressure release hole 83 is provided with a filter 84 that allows gas to pass but prevents passage of toner. As a result, the gas fed into the small sub hopper 80 from the discharge port 38 of the pump 30 is discharged from the pressure release hole 83 through the pressure release path L while suppressing toner leakage from the pressure release hole 83. Can be depressurized. Therefore, it is possible to suppress the toner from being disturbed near the toner end sensor 22 by the gas that has reached the sub hopper 20 from the small sub hopper 80, and the detection accuracy of the toner end sensor 22 can be improved.

  As a position where the pressure relief hole 83 is provided in the small sub hopper 80, it is desirable to provide the pressure relief hole 83 upstream of the discharge port 38 of the pump 30 in the small sub hopper 80 in the toner conveying direction. As a result, the gas from the pump 30 escapes in the direction opposite to the toner conveyance direction in the small sub hopper 80. Thereby, the fluidity (space ratio) of the toner conveyed from the small sub hopper 80 to the sub hopper 20 is easily lowered.

  In addition, since the pump 30 used in the present embodiment is a diaphragm pump, the diaphragm pump is a pump that conveys a large amount of gas. Therefore, the effect obtained by providing the pressure release hole 83 as described above can be further improved. It can be demonstrated. Even when a bellows pump is used as the pump 30, since the bellows pump is a pump that conveys a large amount of gas, the above-described effect can be exhibited more similarly to the case of using a diaphragm pump.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect A)
A powder pump such as a pump 30 for transporting powder mixed with gas, a first powder reservoir such as a sub hopper 20 for temporarily storing powder, and a first powder reservoir provided in the first powder reservoir In a powder conveying device such as a developer conveying device 190, which includes a powder amount detecting means such as a toner end sensor 22 for detecting the amount of powder in the first powder storage unit, the powder pump and the first A second powder storage unit such as a small sub hopper 80 that temporarily stores the powder conveyed by the powder pump is provided between the one powder storage unit. According to this, as described in the above embodiment, powder detection can be performed with high accuracy by the powder amount detection means.
(Aspect B)
In (Aspect A), as the powder pump, by using a positive displacement pump that alternately generates positive pressure and negative pressure by changing the volume of the internal space, the fluidity of the powder is improved and the powder pump is conveyed. Therefore, a large amount of powder can be conveyed at high speed, and the efficiency of conveying the powder can be increased.
(Aspect C)
In (Aspect A) or (Aspect B), a powder conveying member such as a screw 81 for conveying powder is provided in the second powder storage unit. According to this, it becomes possible to carry the powder while stabilizing the bulk density of the powder.
(Aspect D)
In (Aspect A) or (Aspect B), a powder agitating member such as a toner agitating member 82 for agitating powder is provided in the second powder reservoir. According to this, as described in the above embodiment, the fluidity can be ensured by loosening the powder.
(Aspect E)
In (Aspect C) or (Aspect D), the powder conveying member or the powder stirring member and the powder pump are driven in synchronization. According to this, as described in the above embodiment, the retention of powder in the second powder storage unit is suppressed, and the powder supplied from the powder pump is stably supplied to the first powder storage unit. can do.
(Aspect F)
In any one of (Aspect A) to (Aspect E), the second powder storage part is provided with a pressure release hole for performing pressure release in the second powder storage part. According to this, as described in the above embodiment, the disturbance of the powder due to the air current is suppressed in the vicinity of the powder amount detection means, and the detection accuracy of the powder amount detection means can be improved.
(Aspect G)
In any one of (Aspect A) to (Aspect F), the powder pump is a diaphragm pump. According to this, the conveyance efficiency of powder can be improved more.
(Aspect H)
In any one of (Aspect A) to (Aspect F), the powder pump is a bellows pump. According to this, the conveyance efficiency of powder can be improved more.
(Aspect I)
(Aspect E) to (Aspect H), the pressure release hole 83 or the like on the upstream side in the powder conveyance direction from the powder discharge port such as the discharge port 38 of the powder pump in the second powder reservoir. The pressure release hole was provided. According to this, as explained about the above-mentioned embodiment, it becomes easy to lower the fluidity (space factor) of the powder conveyed to the first powder reservoir.
(Aspect J)
In any one of (Aspect A) to (Aspect I), the powder amount detection means is arranged on a vertical plane passing through a discharge port such as the discharge port 82 of the second powder storage unit in the first powder storage unit. It was installed at a position that almost coincided. According to this, as described in the above embodiment, the occurrence of defective powder recovery in the first powder reservoir can be suppressed.
(Aspect K)
In any one of (Aspect A) to (Aspect I), the powder amount detection means is installed at a position that coincides with a vertical plane passing through the outlet of the second powder storage part in the first powder storage part. did. According to this, as described in the above embodiment, the occurrence of defective powder recovery in the first powder reservoir can be suppressed.
(Aspect L)
In any one of (Aspect A) to (Aspect I), the powder amount detection means is installed on the downstream side in the powder conveyance direction of the discharge port of the second powder storage part in the first powder storage part. . According to this, as described in the above embodiment, the occurrence of defective powder recovery in the first powder reservoir can be suppressed. Moreover, powder can be reliably detected by installing powder amount detection means downstream of the discharge port in the powder conveyance direction.
(Aspect M)
In any one of (Aspect A) to (Aspect L), the powder amount detection means can be configured using a piezoelectric element.
(Aspect N)
The image forming apparatus includes image forming means such as the image forming unit 2 and the powder conveying apparatus according to any one of (Aspect A) to (Aspect M). According to this, as described in the above embodiment, good image formation can be performed over time.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Image forming unit 3 Cleaning part 4 Primary transfer roller 8 Charging part 9 Developing part 10 Developing unit 12 Developing device 12 Developing roller 13a Conveying screw 13b Conveying screw 14 Doctor blade 17 Vertical pipe 20 Sub hopper 20a Side wall 20b Side wall 20c Bearing wall 20d Bearing wall 20e bottom surface 21a screw 21b screw 22 toner end sensor 23 partition wall 23a opening 23b opening 24 transport path 24 first transport path 25 second transport path 26 outlet 27 opening 30 pump 31 discharge valve 32 suction valve 33 diaphragm 34 pump case 35 motor 36 Eccentric shaft portion 37 Inflow port 38 Discharge port 60 Toner storage unit 61 Holder 62 Storage unit sensor 64 Discharge port 70 Toner container 71 Seal member 75a Agitator 76 Rotating shaft 78 Rotation drive source 80 Sub hopper 81 Screw 82 Toner stirring member 83 Pressure release hole 84 Filter 82 Ejection port 95 Control unit 100 Image forming apparatus 110 Main body 111 Optical writing unit 121 Paper feed cassette 122 Paper feed cassette 123 Paper feed roller 124 Paper feed roller 126 Registration roller pair 127 Intermediate transfer belt 134 Fixing part 135 Fixing roller 136 Pressure roller 137 Coil 138 Paper discharge roller 140 Paper feed part 150 Image forming part 160 Replenishing means 180 Paper discharge part 181 Paper discharge tray 190 Developer transport device 601 Casing 602 Conical surface 603 Discharge path 604 pipe

Japanese Patent No. 3985753

Claims (14)

A powder pump for conveying powder mixed with gas;
A first powder storage section for temporarily storing powder;
In a powder conveying apparatus provided with a powder amount detection means provided in the first powder storage unit for detecting the amount of powder in the first powder storage unit,
A powder transporter characterized in that a second powder reservoir for temporarily storing the powder transported by the powder pump is provided between the powder pump and the first powder reservoir. apparatus. In the powder conveying apparatus according to claim 1,
A powder conveying apparatus using a positive displacement pump that alternately generates positive pressure and negative pressure by changing the volume of the internal space as the powder pump. In the powder conveying apparatus according to claim 1 or 2,
A powder conveying apparatus comprising a powder conveying member for conveying powder in the second powder storage unit. In the powder conveying apparatus according to claim 1 or 2,
A powder conveying apparatus comprising a powder agitating member for agitating powder in the second powder storage unit. In the powder conveying apparatus according to claim 3 or 4,
The powder conveying device, wherein the powder conveying member or the powder agitating member and the powder pump are driven synchronously. In the powder conveying apparatus according to any one of claims 1 to 5,
A powder conveying apparatus, wherein the second powder storage part is provided with a pressure release hole for performing pressure release in the second powder storage part. In the powder conveying apparatus according to any one of claims 1 to 6,
The powder conveying apparatus, wherein the powder pump is a diaphragm pump. In the powder conveying apparatus according to any one of claims 1 to 6,
The powder conveying apparatus, wherein the powder pump is a bellows pump. In the powder conveying apparatus according to any one of claims 6 to 8,
The powder conveyance device according to claim 1, wherein the pressure release hole is provided upstream of the powder discharge port of the powder pump in the second powder storage unit in the powder conveyance direction. In the powder conveying apparatus according to any one of claims 1 to 9,
The powder conveyance device, wherein the powder amount detection means is installed at a position substantially coincident with a vertical plane passing through the discharge port of the second powder storage unit in the first powder storage unit. In the powder conveying apparatus according to any one of claims 1 to 9,
The powder conveyance device, wherein the powder amount detection means is installed at a position corresponding to a vertical plane passing through the discharge port of the second powder storage unit in the first powder storage unit. In the powder conveying apparatus according to any one of claims 1 to 9,
The developer conveying device according to claim 1, wherein the powder amount detecting means is installed on the downstream side in the powder conveying direction of the discharge port of the second powder storing unit in the first powder storing unit. In the powder conveying apparatus according to any one of claims 1 to 12,
A powder conveying apparatus comprising the powder amount detecting means using a piezoelectric element.   An image forming apparatus comprising: an image forming unit; and the powder conveying device according to claim 1.

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