Powder conveying device and image forming device

Abstract

To provide a powder conveying device that can prevent clogging of a connection conveyance path with powder.SOLUTION: When D1 is the cross-sectional area of a cross section orthogonal to a powder conveyance direction of a nozzle conveyance path 61 such as a first conveyance path, d1 is the cross-sectional area of a cross section orthogonal to a powder conveyance direction of a first conveying member such as a nozzle conveying screw 164, D2 is the cross-sectional area of a cross section orthogonal to a powder conveyance direction of a relay conveyance path 65 such as a second conveyance path, and d2 is the cross-sectional area of a cross section orthogonal to a powder conveyance direction of a relay conveying screw 165 such as a second conveying member, a powder conveying device has the relationship of (D1-d1)<(D2-d2).SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a powder transport device and an image forming apparatus. [Background technology]

[0002] Conventionally, a powder conveying device is known that includes a first conveying path having an intake port for taking in powder and having a first conveying member disposed therein for conveying the powder, a second conveying path having an outlet for discharging powder and having a second conveying member disposed therein for conveying the powder, and a connecting conveying path that connects the first conveying path and the second conveying path and conveys the powder in the first conveying path to the second conveying path.

[0003] Patent Document 1 describes a powder transport device having a first powder transport path in which a transport screw is disposed as a first transport member and which takes in powder toner from a toner bottle and transports it horizontally, and a second powder transport path having an outlet for discharging toner to a developing device and in which a transport screw is disposed as a second transport member and which transports toner horizontally toward the outlet. The first powder transport path is disposed above the second powder transport path, and a connecting transport path connecting the first transport path and the second transport path drops the toner transported from the first transport path and transports it to the second transport path. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there were cases where the powder clogged the connecting conveying path. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a powder conveying device including a first conveying path having an intake port for taking in powder and having a first conveying member disposed therein for conveying the powder, a second conveying path having an outlet for discharging powder and having a second conveying member disposed therein for conveying the powder, and a connecting conveying path connecting the first conveying path and the second conveying path for conveying the powder in the first conveying path to the second conveying path,the first conveying member and the second conveying member are conveying screws each including a shaft and a blade spirally provided on an outer peripheral surface of the shaft, The cross-sectional area of ​​the first conveying path perpendicular to the powder conveying direction is D1, The cross-sectional area of ​​the first conveying member perpendicular to the powder conveying direction is d1, The cross-sectional area of ​​the second conveying path perpendicular to the powder conveying direction is D2, When the cross-sectional area of ​​the second conveying member perpendicular to the powder conveying direction is d2, The relationship (D1-d1)<(D2-d2) exists. The shaft of the first conveying member is thicker than the shaft of the second conveying member, and the diameter of the first conveying path is larger than the diameter of the second conveying path. It is characterized by the following. [Effects of the Invention]

[0006] According to the present invention, powder clogging in the connecting conveying path can be suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of a copying machine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the general configuration of an imaging unit corresponding to yellow. [Figure 3] FIG. 2A is a perspective view showing a state in which a toner container is installed in a toner supply device, and FIG. 2B is a schematic view. [Figure 4] FIG. 2 is a schematic plan view showing an example of a drive device. [Figure 5] FIG. 10 is a schematic plan view showing another example of the drive device. [Figure 6] FIG. 2A is a perspective view of a nozzle conveying screw, and FIG. 2B is a perspective view of a relay conveying screw. [Figure 7] FIG. 4A is a schematic cross-sectional view of a conveying nozzle, and FIG. 4B is a schematic cross-sectional view of a relay conveying path. [Figure 8] FIG. 10 is a perspective view of a main part showing a modified example of the nozzle conveying screw. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will be described below in which the present invention is applied to a copying machine (hereinafter referred to as copying machine 500) as an image forming apparatus. 1 is a schematic diagram of a copier 500 according to this embodiment. The copier 500 is made up of a copier main body (hereinafter referred to as a printer unit 100), a paper feed table (hereinafter referred to as a paper feed unit 200), and a scanner (hereinafter referred to as a scanner unit 400) attached to the printer unit 100.

[0009] Four developer containers corresponding to the respective colors (yellow, magenta, cyan, and black), that are also powder containers, are detachably (replaceably) installed in the toner container storage section 70 provided at the top of the printer section 100. An intermediate transfer unit 85 is disposed below the toner container storage section 70.

[0010] The intermediate transfer unit 85 is composed of an intermediate transfer belt 48, four primary transfer bias rollers 49 (Y, M, C, K), a secondary transfer backup roller 82, multiple tension rollers, an intermediate transfer cleaning device, etc. The intermediate transfer belt 48 is stretched and supported by multiple roller members, and moves endlessly in the direction of the arrow in FIG. 1 by the rotational drive of the secondary transfer backup roller 82, which is one of the multiple roller members.

[0011] In the printer unit 100, four image forming units 46 (Y, M, C, K) which are image forming means corresponding to each color are arranged side by side so as to face the intermediate transfer belt 48. In addition, four toner supply devices 60 (Y, M, C, K) corresponding to the four toner containers 32 (Y, M, C, K) are arranged below the four toner containers 32 (Y, M, C, K). The toner contained in the toner containers 32 (Y, M, C, K) is supplied (replenished) by the corresponding toner supply devices 60 (Y, M, C, K) into the developing devices (powder-using units) which are developing means of the image forming units 46 (Y, M, C, K) corresponding to each color.

[0012] 1, the printer unit 100 also includes an exposure device 47, which is a latent image forming means, below the four image creating units 46. The exposure device 47 exposes the surface of a photoreceptor 41, which will be described later, based on image information of an original image read by the scanner unit 400 or image information input from an external device such as a personal computer, thereby forming an electrostatic latent image on the surface of the photoreceptor 41. The exposure device 47 included in the printer unit 100 uses a laser beam scanner system that uses a laser diode, but other configurations such as an LED array may also be used as the exposure means.

[0013] FIG. 2 is a schematic diagram showing the general configuration of the image forming unit 46Y corresponding to yellow. The image forming unit 46Y includes a drum-shaped photoconductor 41Y that serves as an image carrier. The image forming unit 46Y also includes a charging roller 44Y that serves as a charging means, a developing device 50Y that serves as a developing means, a photoconductor cleaning device 42Y, a static eliminator, and other devices that are arranged around the photoconductor 41Y. An image forming process (charging step, exposure step, development step, transfer step, and cleaning step) is then performed on the photoconductor 41Y, forming a yellow image on the photoconductor 41Y.

[0014] The other three image forming units 46 (M, C, K) have substantially the same configuration as the image forming unit 46Y corresponding to yellow, except that they use different toner colors, and form images of the colors corresponding to the respective toners on the respective photoconductors 41 (M, C, K). Below, we will omit the description of the other three image forming units 46 (M, C, K) as appropriate, and will only describe the image forming unit 46Y corresponding to yellow.

[0015] The photoreceptor 41Y is driven to rotate in the clockwise direction in FIG. 2 by a drive motor. Then, the surface of the photoreceptor 41Y is uniformly charged at a position facing the charging roller 44Y (charging process). Thereafter, the surface of the photoreceptor 41Y reaches a position irradiated with laser light L emitted from the exposure device 47, and an electrostatic latent image corresponding to yellow is formed by exposure scanning at this position (exposure process). Thereafter, the surface of the photoreceptor 41Y reaches a position facing the developing device 50Y, and the electrostatic latent image is developed at this position to form a yellow toner image (developing process).

[0016] The four primary transfer bias rollers 49 (Y, M, C, K) of the intermediate transfer unit 85 sandwich the intermediate transfer belt 48 between themselves and the photosensitive members 41 (Y, M, C, K), forming primary transfer nips. A transfer bias opposite to the polarity of the toner is applied to the primary transfer bias rollers 49 (Y, M, C, K).

[0017] The surface of the photoreceptor 41Y, on which the toner image has been formed in the development process, reaches a primary transfer nip facing the primary transfer bias roller 49Y across the intermediate transfer belt 48. The toner image on the photoreceptor 41Y is transferred to the intermediate transfer belt 48 at this primary transfer nip (primary transfer process). At this time, a small amount of untransferred toner remains on the photoreceptor 41Y. The surface of the photoreceptor 41Y, which has transferred the toner image to the intermediate transfer belt 48 at the primary transfer nip, reaches a position facing the photoreceptor cleaning device 42Y. At this position, the untransferred toner remaining on the photoreceptor 41Y is mechanically collected by the cleaning blade 42a (cleaning process). Finally, the surface of the photoreceptor 41Y reaches a position facing the static eliminator, where the residual potential on the photoreceptor 41Y is removed. This completes the series of image formation processes performed on the photoreceptor 41Y.

[0018] This image formation process is also performed in the other image forming units 46 (M, C, K) in the same manner as in the yellow image forming unit 46Y. That is, laser light L based on image information is irradiated onto the photoconductors 41 (M, C, K) of each image forming unit 46 (M, C, K) from an exposure device 47 disposed below the image forming unit 46 (M, C, K). More specifically, the exposure device 47 emits laser light L from a light source, and irradiates each photoconductor 41 (M, C, K) with the laser light L via multiple optical elements while scanning with a rotationally driven polygon mirror. Thereafter, the toner images of each color formed on each photoconductor 41 (M, C, K) undergo a development process and are transferred onto an intermediate transfer belt 48.

[0019] 1, and sequentially passes through the primary transfer nips of the primary transfer bias rollers 49 (Y, M, C, K). As a result, the toner images of each color on the photoconductors 41 (Y, M, C, K) are primarily transferred onto the intermediate transfer belt 48 in a superimposed manner, and a color toner image is formed on the intermediate transfer belt 48.

[0020] The toner images of each color are transferred one on top of the other, and the intermediate transfer belt 48, on which a color toner image is formed, reaches a position facing a secondary transfer roller 89. At this position, a secondary transfer nip is formed by sandwiching the intermediate transfer belt 48 between the secondary transfer backup roller 82 and the secondary transfer roller 89. The color toner image formed on the intermediate transfer belt 48 is then transferred onto a recording medium P, such as transfer paper, that has been transported to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 48. After passing through the secondary transfer nip, the intermediate transfer belt 48 reaches the position of an intermediate transfer cleaning device, where the untransferred toner on its surface is collected, thereby completing the series of transfer processes that take place on the intermediate transfer belt 48.

[0021] Next, the movement of the recording medium P will be described. The recording medium P transported to the secondary transfer nip is transported from a paper feed tray 26 of a paper feed unit 200 disposed below the printer unit 100 via a paper feed roller 27 and a pair of registration rollers 28. More specifically, a plurality of recording media P are stored in a stack in the paper feed tray 26. When the paper feed roller 27 is driven to rotate counterclockwise in FIG. 1, the topmost recording medium P is transported toward the roller nip formed by the two rollers of the pair of registration rollers 28.

[0022] The recording medium P conveyed to the registration roller pair 28 stops temporarily at the roller nip position of the registration roller pair 28, which has stopped rotating. Then, in synchronization with the timing at which the color toner image on the intermediate transfer belt 48 reaches the secondary transfer nip, the registration roller pair 28 is rotated and the recording medium P is conveyed toward the secondary transfer nip. In this way, the desired color toner image is transferred onto the recording medium P.

[0023] The recording medium P onto which the color toner image has been transferred at the secondary transfer nip is transported to the position of the fixing device 86. In the fixing device 86, the color toner image transferred onto the surface is fixed onto the recording medium P by the heat and pressure of the fixing belt and pressure roller. After passing through the fixing device 86, the recording medium P passes between the rollers of the paper discharge roller pair 29 and is discharged to the outside of the apparatus. The recording medium P discharged to the outside of the apparatus by the paper discharge roller pair 29 is stacked in order on the stack unit 30 as an output image. In this way, a series of image formation processes in the copier 500 is completed.

[0024] Next, a more detailed description will be given of the configuration and operation of the developing device 50 in the image forming unit 46. Note that, although the description will be given here using the image forming unit 46Y corresponding to yellow as an example, the same applies to the image forming units 46 for the other colors (M, C, K).

[0025] As shown in FIG. 2, the developing device 50Y is composed of a developing roller 51Y, a doctor blade 52Y, two developer transport screws 55Y, and a toner concentration detection sensor 56Y. The developing roller 51Y faces the photoconductor 41Y, and the doctor blade 52Y faces the developing roller 51Y. The two developer transport screws 55Y are disposed in two developer containers (53Y, 54Y). The developing roller 51Y is composed of a magnetic roller fixed inside and a sleeve that rotates around the magnetic roller. The first developer container 53Y and the second developer container 54Y contain two-component developer G consisting of carrier and toner. The second developer container 54Y is connected to the outlet 66 (see FIG. 3) of the toner supply device through an opening formed above it. The toner concentration detection sensor 56Y detects the toner concentration of the developer G in the second developer container 54Y.

[0026] The developer G in the developing device 50 is circulated between the first developer storage section 53Y and the second developer storage section 54Y while being agitated by two developer transport screws 55Y. The developer G in the first developer storage section 53Y is transported by one of the developer transport screws 55Y and supplied to and carried on the sleeve surface of the developing roller 51Y by the magnetic field generated by the magnet roller in the developing roller 51Y. The sleeve of the developing roller 51Y rotates counterclockwise as indicated by the arrow in FIG. 2, and the developer G carried on the developing roller 51Y moves along the developing roller 51Y as the sleeve rotates. At this time, the toner in the developer G is charged to a potential of opposite polarity to that of the carrier due to frictional charging with the carrier in the developer G and is electrostatically attracted to the carrier. The toner is then carried on the developing roller 51Y together with the carrier, which is attracted by the magnetic field generated on the developing roller 51Y.

[0027] The developer G carried on the developing roller 51Y is transported in the direction of the arrow in FIG. 2 and reaches the doctor section where the doctor blade 52Y and the developing roller 51Y face each other. The amount of developer G on the developing roller 51Y is adjusted as it passes through the doctor section, and then it is transported to the developing area, which is the position facing the photosensitive member 41Y. In the developing area, the toner in the developer G is attracted to the latent image formed on the photosensitive member 41Y by the developing electric field formed between the developing roller 51Y and the photosensitive member 41Y. The developer G remaining on the surface of the developing roller 51Y that has passed through the developing area reaches above the first developer container 53Y as the sleeve rotates, and is separated from the developing roller 51Y at this position.

[0028] The developer G in the developing device 50Y is adjusted so that the toner concentration is within a predetermined range. Specifically, the toner contained in the toner container 32Y is replenished into the second developer accommodating unit 54Y via a toner replenishing device 60Y, which will be described later, in accordance with the amount of toner consumed by development in the developer G in the developing device 50Y. The toner supplied to the second developer storage portion 54Y is mixed and stirred together with the developer G by the two developer transport screws 55Y, and circulates between the first developer storage portion 53Y and the second developer storage portion 54Y.

[0029] The toner in each toner container 32 (Y, M, C, K) installed in the toner container storage unit 70 of the printer unit 100 is replenished into each developing device 50 (Y, M, C, K) as appropriate in accordance with the toner consumption in the developing device 50 (Y, M, C, K) of each color. At this time, the toner in each toner container 32 (Y, M, C, K) is replenished by a toner replenishing device 60 (Y, M, C, K) provided for each toner color.

[0030] Next, the toner supply devices 60 (Y, M, C, K) will be described. FIG. 3(a) is a perspective view showing a toner container 32 installed in a toner supply device 60, which is a powder conveying device, and FIG. 3(b) is a schematic diagram. The toner conveyance direction of the relay conveyance path 65 is normally perpendicular to the plane of FIG. 3(b). However, in FIG. 3(b), the toner conveyance direction of the relay conveyance path 65 is shown as the same direction as the conveyance nozzle 61 to make the configuration easier to understand. The four toner supply devices 60 (Y, M, C, K) and toner containers 32 (Y, M, C, K) have substantially the same structure except for the colors of toner used in the image creation process. Therefore, the color codes Y, M, C, and K will be omitted as appropriate in the following description.

[0031] The toner supply device 60 has a conveying nozzle 61 as a first conveying path, a vertical conveying path 64 as a connecting conveying path, and a relay conveying path 65 as a second conveying path. When the toner container 32 as a powder container is attached to the toner container storage unit 70 of the printer unit 100, the conveying nozzle 61 of the toner supply device 60 is inserted from the container tip side of the toner container 32 in conjunction with the attachment operation. This allows the inside of the toner container 32 and the inside of the conveying nozzle 61 to communicate with each other.

[0032] The toner container 32 is a substantially cylindrical toner bottle and is mainly composed of a container front cover 34 that is held non-rotatably in the toner container holder 70, and a container body 33 that is integrally formed with a container gear 301. The container body 33 is held rotatably relative to the container front cover 34.

[0033] A rotational drive is input from the drive unit 90 (see FIG. 4) to the container gear 301 (see FIG. 4) provided on the container body 33, thereby rotating the container body 33. As the container body 33 rotates, the toner contained inside the container body 33 is transported toward the transport nozzle 61 along the longitudinal direction of the container body by the spiral protrusion 302 formed in a spiral shape on the inner circumferential surface of the container body 33.

[0034] A pumping section is provided on the container front cover side of the container body 33, which pumps up the toner transported to the container front cover side by the rotation of the container body 33. This pumping section pumps up the toner above the transport nozzle 61 inserted into the toner container, and the toner falls into a nozzle opening 62 serving as an intake port provided at the end of the transport nozzle 61 on the toner container side, thereby supplying the toner into the transport nozzle 61.

[0035] A nozzle transport screw 164 serving as a first transport member is disposed within the transport nozzle 61, and when rotational drive is input from the drive device 90 (see FIG. 4), the nozzle transport screw 164 rotates and transports the toner supplied into the transport nozzle 61 in a horizontal direction. The downstream end of the transport nozzle 61 in the transport direction is connected to the vertical transport path 64, and the toner transported by the nozzle transport screw 164 falls under its own weight down the vertical transport path 64 to be transported to the relay transport path 65.

[0036] A relay transport screw 165 is disposed in the relay transport path 65 as a second transport member, and when rotational drive is input from the drive device 90 (see FIG. 4), the relay transport screw 165 rotates and transports the toner supplied into the relay transport path 65 in a horizontal direction. A discharge port 66 is provided at the downstream end of the relay transport path 65 in the transport direction, and the toner transported by the relay transport screw 165 falls from the discharge port 66 under its own weight and is replenished into the developing device 50.

[0037] The relay conveying path 65 is made of an elastic material such as elastomer rubber, and the relay conveying screw 165 is also made of an elastic material such as elastomer rubber, so that the relay conveying path 65 is configured to be elastically deformable.

[0038] The diameter of the relay conveying path 65 is shorter than the diameter of the conveying nozzle 61. Furthermore, the rotation speed of the nozzle conveying screw 164 is 189 rpm, and the rotation speed of the relay conveying screw 165 is 237 rpm, so that the rotation speed of the relay conveying screw 165 is faster than the rotation speed of the nozzle conveying screw 164. Note that the rotation speeds of each conveying screw are just examples, and may be set appropriately depending on the device configuration.

[0039] FIG. 4 is a schematic plan view showing an example of the driving device 90. As shown in FIG. The driving device 90 uses a driving motor 91 as a driving source to drive the toner container 32, the nozzle conveying screw 164, and the relay conveying screw 165. In this embodiment, a stepping motor is used as the driving motor.

[0040] A relay gear portion 92a of a branch gear 92 meshes with a motor gear 91a of the drive motor 91. The driving force of the drive motor 91 is transmitted to the container gear 301 via a first bottle gear 93 that meshes with an upper portion of the relay gear portion 92a of the branch gear 92 and a second bottle gear 94 that is arranged coaxially with the first bottle gear 93. This causes the container body 33 to rotate.

[0041] The driving force of the drive motor 91 is transmitted from the relay gear portion 92a via the nozzle idler gear 97 to a nozzle screw gear 98 fixed to the shaft 164a of the nozzle conveying screw 164, thereby driving the nozzle conveying screw 164 to rotate. The driving force of the drive motor 91 is transmitted from the bevel gear 92b of the branch gear 92 to a second bevel gear 96 fixed to the shaft 165a of the relay conveying screw 165, thereby driving the relay conveying screw 165 to rotate.

[0042] FIG. 5 is a schematic plan view showing another example of the driving device 190. As shown in FIG. 5, a branch gear 193 is fixed to the shaft 164a of the nozzle conveying screw 164. The driving force of the drive motor 191 is transmitted from the motor gear 191a via the idler gear 192 to the relay gear portion 193a of the branch gear 193, thereby driving the nozzle conveying screw 164 to rotate.

[0043] Furthermore, the driving force of the drive motor 191 is transmitted from the relay gear portion 193a to the bottle idler gear 194 and the first bottle gear 195. Then, the driving force of the drive motor is transmitted to the container gear 301 via the second bottle gear 196 that is arranged coaxially with the first bottle gear 195, and the container body 33 is rotated.

[0044] Furthermore, the driving force of the drive motor 191 transmitted to the relay gear portion 193a is transmitted to the second bevel gear 197 via the first bevel gear 193b of the branch gear 193, and the relay conveying screw 165 is driven to rotate.

[0045] As shown in Figures 4 and 5, the drive device uses a single drive motor to rotate the toner container, the nozzle transport screw 164, and the relay transport screw 165. This allows for a reduction in the number of drive motors, compared to when multiple drive motors are used to rotate these components, thereby reducing the cost of the device. It also allows for a more compact device. Furthermore, by consolidating the drive motors, which generate a large amount of heat, into a single motor, the temperature rise in the toner container 32 and the transport paths 61, 64, and 65 of the toner supply device is suppressed. This makes it possible to suppress toner aggregation and toner adhesion in the toner container 32 and the transport paths 61, 64, and 65 of the toner supply device.

[0046] The drive device 90 shown in FIG. 4 is more preferable than the drive device 190 shown in FIG. 5 because it can prevent toner clogging in the vertical transport path 64 . 4, the gear meshing location for driving force transmission from the relay gear portion 92a to the relay conveying screw 165 is one location, between the first bevel gear 92b and the second bevel gear 96. On the other hand, the gear meshing locations for driving force transmission to the nozzle conveying screw 164 are two locations, between the relay gear portion 92a and the nozzle idler gear 97, and between the nozzle idler gear 97 and the nozzle screw gear 98.

[0047] 4, the number of meshing points from the relay gear portion 92a to the relay conveying screw 165 is smaller than the number of meshing points from the relay gear portion 92a to the nozzle conveying screw. Therefore, due to gear play, the relay conveying screw 165 starts to rotate before the nozzle conveying screw 164. In this way, in the drive device 90 shown in FIG. 4, the relay conveying screw 165 starts to rotate first, which is preferable because it is possible to prevent toner from accumulating in the vertical conveying path 64 and to prevent toner clogging in the vertical conveying path 64.

[0048] Due to the layout of the device, the diameter of the relay transport path 65 is smaller than the diameter of the transport nozzle 61. Conventionally, relay transport screws with a shaft diameter equal to that of the nozzle transport screw were used. As a result, the toner transport area within the relay transport path was narrower than the toner transport area within the transport nozzle. Therefore, conventionally, the rotation speed of the relay transport screw 165 was set faster than the rotation speed of the nozzle transport screw 164, and the toner transport speed of the relay transport path 65 was set faster than the toner transport speed of the transport nozzle 61, thereby making the amount of toner that can be transported from the vertical transport path 64 to the relay transport path greater than the amount of toner transported from the transport nozzle 61 to the vertical transport path 64. However, due to variations in the characteristics of the toner being transported and variations in the ratio between the rotation speeds of the relay transport screw 165 and the nozzle transport screw 164, the amount of toner transported from the transport nozzle 61 to the vertical transport path could sometimes be greater than the amount of toner that can be transported from the vertical transport path to the relay transport path.

[0049] If the rotation speed of the nozzle transport screw, the rotation speed of the relay transport screw, and the rotation speed of the toner container are set by the gear ratio of the drive device, when the amount of toner transported from the transport nozzle 61 to the vertical transport path 64 becomes greater than the specified amount, it is not possible to increase the amount of toner that can be transported from the vertical transport path to the relay transport path by increasing only the rotation speed of the relay transport screw. As a result, toner accumulates in the vertical transport path 64, and there is a risk that the vertical transport path 64 will eventually become clogged with toner.

[0050] Furthermore, when the type of toner or the specifications of the toner are changed during the development stage of the device, there are cases where the rotation speed ratio between the nozzle conveying screw 164 and the relay conveying screw 165 up to that point is such that toner clogging frequently occurs in the vertical conveying path 64. Therefore, it is conceivable to change the rotation speed ratio between the nozzle conveying screw 164 and the relay conveying screw 165 to prevent toner clogging. However, as shown in FIGS. 4 and 5, in the case of drive devices 90 and 190 that rotate and drive the nozzle conveying screw 164 and the relay conveying screw 165 with a single drive motor, it is necessary to change the layout of the drive device 90 (gear arrangement, gear ratio, etc.). Therefore, it is not easy to change the rotation speed ratio between the nozzle conveying screw 164 and the relay conveying screw 165.

[0051] It is also possible to narrow the screw pitch of the nozzle transport screw 164 compared to the screw pitch of the relay transport screw 165. By narrowing the screw pitch of the nozzle transport screw 164 compared to the screw pitch of the relay transport screw 165, the toner transport speed in the relay transport path 65 can be made faster than the toner transport speed of the transport nozzle. This allows for the transport nozzle to be replaced with one with a narrower screw pitch if toner clogging occurs during the development stage, thereby preventing toner clogging in the vertical transport path 64 without changing the layout of the drive devices 90 and 190. However, narrowing the screw pitch of the nozzle transport screw 164 increases the pressure in the transport direction, increasing the pressure inside the transport nozzle. As a result, if a clogging occurs inside the transport nozzle due to some accident, problems such as damage to the tube or toner scattering from the joint (seal) between the tubes can occur before the drive motor locks.

[0052] Therefore, in this embodiment, the shaft diameter of the nozzle transport screw 164 and the shaft diameter of the relay transport screw 165 are set to satisfy the following relational expression (Equation 1), thereby suppressing toner clogging in the vertical transport path 64. That is, when the cross-sectional area of ​​the transport nozzle 61 perpendicular to the toner transport direction is D1, the cross-sectional area of ​​the nozzle transport screw 164 perpendicular to the toner transport direction is d1, the cross-sectional area of ​​the relay transport path 65 perpendicular to the toner transport direction is D2, and the cross-sectional area of ​​the relay transport screw 165 perpendicular to the toner transport direction is d2, (D1-d1)<(D2-d2) (Formula 1) This is the relationship.

[0053] 6(a) is a perspective view of the nozzle conveying screw 164, and FIG. 6(b) is a perspective view of the relay conveying screw 165. As shown in FIG. 6, the nozzle conveying screw 164 and the relay conveying screw 165 have shafts 164a, 165a and blades 164b, 164b spirally wound around the shafts. The nozzle conveying screw 164 is a rigid body made of molybdenum, and the relay conveying screw 165 is an elastic body made of elastomer rubber. The shaft diameter of the relay conveying screw 165 is smaller than the shaft diameter of the nozzle conveying screw 164.

[0054] 7(a) is a schematic cross-sectional view of the conveying nozzle 61 (a cross-sectional view taken along line AA in FIG. 3(b)), and FIG. 7(b) is a schematic cross-sectional view of the relay conveying path 65 (a cross-sectional view taken along line BB in FIG. 3(b)). In this embodiment, diameter L1 from the axial center of the nozzle conveying screw 164 to the top of the blade 164b is approximately the same as the inner diameter of the conveying nozzle 61, and the entire conveying nozzle gap X1 is the area (hereinafter simply referred to as the toner conveying area) where toner can be conveyed by the nozzle conveying screw 164. Furthermore, diameter L2 from the axial center of the relay conveying screw 165 to the top of the blade 165b is approximately the same as the inner diameter of the relay conveying path 65, and the entire gap X2 of the relay conveying path 65 is the toner conveying area of ​​the relay conveying screw 165.

[0055] When the entire gap between the conveying nozzle 61 and the relay conveying path 65 constitutes the toner conveying region, a larger gap allows for more toner to be conveyed. Therefore, the shaft 165a of the relay conveying screw 165 is made thinner than the shaft 164a of the nozzle conveying screw 164 to satisfy the relationship of Equation 1 described above. As is clear from FIG. 7 , satisfying the relationship of Equation 1 allows for a larger cross-sectional area of ​​the gap X2 in the relay conveying path 65 and a larger cross-sectional area of ​​the gap X1 in the conveying nozzle 61. Because these gaps X1 and X2 are the toner conveying regions of the conveying screws, a larger gap allows for more toner to be conveyed. Therefore, the amount of toner that can be conveyed from the vertical conveying path 64 to the relay conveying path 65 can be increased compared to when the gap X2 in the relay conveying path 65 is smaller than or equal to the gap X1 in the first conveying path. Furthermore, when the toner transport speeds of the transport nozzle 61 and the relay transport path 65 are the same, the maximum toner transport amount of the relay transport path 65 can be made larger than the maximum toner transport amount per unit time of the transport nozzle (the toner transport amount when the gap X1 is filled with toner). This prevents toner from accumulating in the vertical transport path 64, and prevents toner clogging in the vertical transport path 64.

[0056] In particular, in this embodiment, the relationship of Equation 1 is satisfied and the rotation speed of the relay transport screw 165 is set to be faster than the rotation speed of the nozzle transport screw 164, thereby further suppressing toner clogging in the vertical transport path 64. Furthermore, compared to suppressing toner clogging in the vertical transport path 64 solely through the relationship of Equation 1, the following advantages can be obtained. That is, toner clogging in the vertical transport path 64 can be suppressed without making the shaft of the nozzle transport screw 164 or the shaft of the relay transport screw 165 unnecessarily thick or thin. Furthermore, the margin of the relay transport path 65 for the amount of toner transported from the transport nozzle 61 to the vertical transport path 64 can be increased. As a result, even if the amount of toner transported from the transport nozzle 61 to the vertical transport path 64 is slightly greater than the specified amount due to variations in toner characteristics, the toner can be transported to the relay transport path 65 without accumulating in the vertical transport path 64.

[0057] Furthermore, compared to the case where the screw pitch of the nozzle conveying screw 164 is narrower than the screw pitch of the relay conveying screw 165 to prevent toner clogging in the vertical conveying path 64, the following advantages can be obtained: Namely, the increase in pressure inside the conveying nozzle 61 can be prevented, and when clogging occurs inside the conveying nozzle, damage to the pipe or scattering of toner from the joints (sealed portions) can be prevented.

[0058] Furthermore, by making the shaft 165a of the relay conveying screw 165 thinner than the shaft 164a of the nozzle conveying screw 164, the rigidity of the relay conveying screw 165 can be reduced, making it easier for the relay conveying screw 165 to elastically deform in accordance with the elastic deformation of the relay conveying path 65.

[0059] Furthermore, in this embodiment, if the type of toner is changed during the development stage of the device and toner clogging frequently occurs in the vertical transport path 64, it is possible to suppress toner clogging in the following way: That is, the nozzle transport screw 164 is changed to one with a larger shaft diameter, or the relay transport screw 165 is changed to one with a smaller shaft diameter. This makes it possible to suppress toner clogging in the vertical transport path 64 with a simpler change than when the rotation speed ratio between the nozzle transport screw 164 and the relay transport screw 165 is changed to suppress toner clogging in the vertical transport path 64.

[0060] FIG. 8 is a perspective view of a main part showing a modified example of the nozzle conveying screw 164. As shown in FIG. A nozzle conveying screw 164 of a modified example shown in FIG. 8 has a blade 164b provided with a plurality of notches 164c. With this configuration, the toner is not transported by the blades at the notched portions 164c of the blades 164b, which reduces the amount of toner transported by the transport nozzle 61 per unit time.

[0061] Therefore, by using the nozzle conveying screw 164 with a notched blade as shown in FIG. 8 and the relay conveying screw 165 with a blade without a notched blade as shown in FIG. 6(b), the following advantage can be obtained. That is, it is possible to widen the difference between the amount of toner conveyed per unit time through the relay conveying path and the amount of toner conveyed per unit time through the conveying nozzle. As a result, there is an advantage in that toner clogging of the vertical conveying path 64 can be suppressed.

[0062] By using the nozzle transport screw 164 shown in FIG. 8, the difference between the amount of toner transported per unit time from the transport nozzle 61 to the vertical transport path 64 and the amount of toner transported per unit time from the vertical transport path 64 to the relay transport path can be increased without significantly increasing the difference between (D1-d1) and (D2-d2). In particular, if the shaft diameter is too thick, causing the blade height to be lowered beyond a certain level, or if the screw pitch is narrowed beyond a certain level to reduce the amount of toner transport, the gaps between the blades may become filled with accumulated toner depending on the toner characteristics and the operating environment, significantly reducing the screw's transport function. Using the screw shown in FIG. 8 is effective in avoiding such a phenomenon. This prevents toner clogging in the vertical transport path 64. Therefore, toner clogging in the vertical transport path 64 can be prevented without making the shaft of the nozzle transport screw 164 unnecessarily thick or the shaft of the relay transport screw 165 unnecessarily thin.

[0063] Furthermore, by using the nozzle transport screw 164 shown in Fig. 8, the amount of toner transported per unit time by the transport nozzle can be reduced compared to the amount of toner transported per unit time by the relay transport path, even if the relationship in (Equation 1) above is not satisfied. Therefore, even if the relationship in (Equation 1) above is not satisfied, by using the nozzle transport screw 164 shown in Fig. 8, toner clogging in the vertical transport path 64 can be suppressed.

[0064] In the above-described embodiment, an example of applying the present invention to a toner supply device that transports toner in a toner container to a developing device has been described, but the present invention can also be applied to, for example, a device that transports waste toner removed by a cleaning device to a waste toner tank.

[0065] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) A powder transport device such as a toner supply device 60 includes a first transport path such as a transport nozzle 61 having an intake port such as a nozzle opening 62 for taking in powder such as toner and having a first transport member such as a nozzle transport screw 164 disposed therein for transporting the powder, a second transport path such as an relay transport path 65 having an outlet 66 for discharging the powder and having a second transport member such as an relay transport screw 165 disposed therein for transporting the powder, and a connecting transport path such as a vertical transport path 64 connecting the first transport path and the second transport path and transporting the powder in the first transport path to the second transport path, The cross-sectional area of ​​the first conveying path perpendicular to the powder conveying direction is D1, The cross-sectional area of ​​the first conveying member perpendicular to the powder conveying direction is d1, The cross-sectional area of ​​the second conveying path perpendicular to the powder conveying direction is D2, When the cross-sectional area of ​​the second conveying member perpendicular to the powder conveying direction is d2, The relationship is (D1-d1)<(D2-d2). The above (D1-d1) represents the cross-sectional area of ​​the gap between the first conveying path and the first conveying member in a cross section perpendicular to the conveying direction, and the above (D2-d2) represents the cross-sectional area of ​​the gap between the second conveying path and the second conveying member in a cross section perpendicular to the conveying direction. Therefore, by satisfying the relationship (D1-d1)<(D2-d2), the gap between the conveying path and the conveying member of the second conveying path in a cross section perpendicular to the conveying direction can be made larger than that of the first conveying path. Because this gap is a space for powder to enter, more powder can be introduced into the second conveying path than when the gap in the second conveying path is the same as the gap in the first conveying path. Therefore, when the entire gap in the second conveying path is a powder conveying region where powder is conveyed by the second conveying member, more powder can be conveyed than when the gap in the second conveying path is the same as the gap in the first conveying path. This makes it possible to prevent powder from accumulating in the connecting conveying path, compared to when the gap in the second conveying path is the same as the gap in the first conveying path, and toner clogging in the connecting conveying path can be prevented.

[0066] (Aspect 2) In aspect 1, the first conveying member such as the nozzle conveying screw 164 and the second conveying member such as the relay conveying screw 165 are conveying screws having a shaft and a blade spirally arranged on the outer peripheral surface of the shaft, and the length L2 from the center of the shaft of the second conveying member to the top of the blade is slightly shorter than the inner diameter of the second conveying path. According to this, as described in the embodiment, the entire space within the transport path of the second transport path can be used as a powder transport area in which powder is transported by the transport member.

[0067] (Aspect 3) In the first aspect, the shaft of the first conveying member is thicker than the shaft of the second conveying member. This makes it possible to easily realize the above relationship (D1-d1)<(D2-d2).

[0068] (Aspect 3) In the second aspect, the diameter of the first transport path such as the transport nozzle 61 is larger than the diameter of the second transport path such as the relay transport path 65. According to this, even with the above configuration, the above relationship (D1-d1)<(D2-d2) can be easily realized by making the shaft of the first conveying member thicker than the shaft of the second conveying member.

[0069] (Aspect 4) In the second or third embodiment, the blade of the first conveying member such as the nozzle conveying screw 164 has a notch 164c. 8, this makes it possible to further reduce the amount of powder transported per unit time in the first transport path such as the transport nozzle 61. As a result, it is possible to increase the difference between the amount of powder transported per unit time from the first transport path to a connecting transport path such as the vertical transport path 64 and the amount of powder transported per unit time from the connecting transport path to a second transport path such as the relay transport path 65, without making the difference between (D1-d1) and (D2-d2) too large. Therefore, it is possible to prevent powder clogging in the connecting transport path without making the shaft of the first transport member such as the nozzle transport screw 164 thicker than necessary or the shaft of the second transport member such as the relay transport screw 165 thinner than necessary.

[0070] (Aspect 5) In a powder conveying device such as a toner supply device 60 that has a first conveying path such as a conveying nozzle 61 that has an intake port such as a nozzle opening 62 for taking in powder such as toner and has a first conveying member such as a nozzle conveying screw 164 arranged inside for conveying the powder, a second conveying path such as an intermediate conveying path 65 that has an outlet 66 for discharging the powder and has a second conveying member such as an intermediate conveying screw 165 arranged inside for conveying the powder, and a connecting conveying path such as a vertical conveying path 64 that connects the first conveying path and the second conveying path and conveys the powder in the first conveying path to the second conveying path, the first conveying member and the second conveying member are conveying screws that have a shaft and blades that are spirally arranged on the outer surface of the shaft, and the blades of the first conveying member have a cutout portion. 8, this makes it possible to reduce the amount of powder per unit time in the first conveying path such as the conveying nozzle 61. As a result, the amount of toner per unit time conveyed from the first conveying path to the connecting conveying path such as the vertical conveying path 64 can be made smaller than the amount of toner per unit time conveyed from the connecting conveying path to the second conveying path such as the relay conveying path 65, thereby making it possible to prevent powder from accumulating in the connecting conveying path. As a result, it is possible to prevent powder from clogging the connecting conveying path.

[0071] (Aspect 6) In the fourth or fifth embodiment, the blade of the second conveying member such as the relay conveying screw 165 does not have a notch. As a result, as explained using Figure 8, the amount of toner per unit time transported from the first transport path to a connecting transport path such as the vertical transport path 64 can be made smaller than the amount of toner per unit time transported from the connecting transport path to a second transport path such as the relay transport path 65.

[0072] (Aspect 7) In any of the first to sixth aspects, the first conveying path such as the conveying nozzle 61 and the second conveying path such as the relay conveying path 65 convey powder such as toner in the horizontal direction. According to this, by providing the configurations of the first and fourth aspects, it is possible to prevent powder clogging in the connecting conveying path.

[0073] (Aspect 8) In the seventh aspect, the first transport path such as the transport nozzle 61 is disposed above the second transport path such as the relay transport path 65. According to this, in the connecting conveyance path such as the vertical conveyance path 64, powder such as toner is conveyed vertically downward, and the powder is conveyed by falling within the connecting conveyance path. As a result, the powder is likely to accumulate at the connecting point of the connecting conveyance path with the second conveyance path, and powder clogging of the connecting conveyance path is likely to occur. However, by providing the configurations of the above-mentioned aspects 1 and 4, powder clogging in the connecting conveying path can be effectively suppressed.

[0074] (Aspect 9) In any of the first to eighth aspects, the driving force is transmitted from the same driving source such as the drive motor 91 to the first conveying member such as the nozzle conveying screw 164 and the second conveying member such as the relay conveying screw 165 . This allows for a reduction in the number of drive sources, compared to when multiple drive sources such as drive motors are used to rotate these components, as described in the embodiment, and thus reduces the cost of the device. It also allows for a more compact device. Furthermore, by consolidating the drive sources that generate a large amount of heat into one, the temperature rise of each transport path is suppressed, and the occurrence of powder aggregation within each transport path can be suppressed.

[0075] (Aspect 10) In any of aspects 1 to 9, the first conveying member such as the nozzle conveying screw 164 and the second conveying member such as the relay conveying screw 165 are conveying screws having a shaft and blades spirally arranged on the outer peripheral surface of the shaft, and the rotational speed of the second conveying member is faster than the rotational speed of the first conveying member. This makes it possible to further reduce the amount of powder transported per unit time in the first transport path, such as the transport nozzle 61, as described in the embodiment. As a result, it is possible to increase the difference between the amount of powder transported per unit time from the first transport path to a connecting transport path, such as the vertical transport path 64, and the amount of powder transported per unit time from the connecting transport path to a second transport path, such as the relay transport path 65, without making the difference between (D1-d1) and (D2-d2) too large. Therefore, it is possible to prevent powder clogging in the connecting transport path without making the shaft of the first transport member, such as the nozzle transport screw 164, thicker than necessary, or the shaft of the second transport member, such as the relay transport screw 165, thinner than necessary.

[0076] (Aspect 11) In an image forming apparatus equipped with an image forming means such as an image forming unit 46 that forms a toner image and a toner conveying device such as a toner supply device that conveys toner, a powder conveying device according to any one of aspects 1 to 10 was used as the toner conveying device. This can prevent toner clogging. [Explanation of symbols]

[0077] 32: Toner container 33: Container body 34: Container tip cover 46: Imaging section 50: Developing device 60: Toner supply device 61: Conveying nozzle 64: Vertical conveyor 65: Relay transport route 66: Outlet 70: Toner container storage section 90: Drive unit 91: Drive motor 91a: Motor gear 92: Branch gear 92a: Relay gear part 92b: First bevel gear 93: Bottle First Gear 94: Second bottle gear 96: Second bevel gear 97: Nozzle idler gear 98: Nozzle screw gear 164: Nozzle conveying screw 164a: Axis 164b: Feather 164c: Notch 165: Relay transport screw 165a: Axis 165b: Feather 190: Drive unit 191: Drive motor 191a: Motor gear 192: Idler gear 193: Branch gear 193a: Relay gear part 193b: First bulkhead gear 194: Bottle idler gear 195: Bottle First Gear 196: Second bottle gear 197: Second bevel gear 301: Container gear 302 : Spiral projection X1: Gap of the transport nozzle X2: Gap in the relay transport path [Prior art documents] [Patent documents]

[0078] [Patent Document 1] Patent Publication No. 2021-157142

Claims

1. a first conveying path having an intake port for taking in powder and having a first conveying member disposed therein for conveying the powder; a second conveying path having a discharge port for discharging the powder and having a second conveying member disposed therein for conveying the powder; A powder conveying device including a connecting conveying path that connects a first conveying path and a second conveying path and conveys powder in the first conveying path to the second conveying path, the first conveying member and the second conveying member are conveying screws each including a shaft and a blade spirally provided on an outer peripheral surface of the shaft, The cross-sectional area of ​​the first conveying path perpendicular to the powder conveying direction is D1, The cross-sectional area of ​​the first conveying member perpendicular to the powder conveying direction is d1, The cross-sectional area of ​​the second conveying path perpendicular to the powder conveying direction is D2, When the cross-sectional area of ​​the second conveying member perpendicular to the powder conveying direction is d2, The relationship is (D1-d1)<(D2-d2), The shaft of the first conveying member is thicker than the shaft of the second conveying member, A powder conveying device, wherein the diameter of the first conveying path is larger than the diameter of the second conveying path.

2. 2. The powder conveying device according to claim 1, A powder conveying device characterized in that the length from the axial center of the second conveying member to the top of the blade is slightly shorter than the inner diameter of the second conveying path.

3. In the powder conveying device according to claim 1 or 2, A powder conveying device, wherein the blade of the first conveying member has a notch.

4. 4. The powder conveying device according to claim 3, A powder conveying device, characterized in that the blade of the second conveying member does not have a notch portion.

5. The powder conveying device according to any one of claims 1 to 4, The powder conveying device, characterized in that the first conveying path and the second conveying path convey the powder in a horizontal direction.

6. 6. The powder conveying device according to claim 5, The powder conveying device, wherein the first conveying path is disposed above the second conveying path.

7. The powder conveying device according to any one of claims 1 to 6, A powder conveying device, characterized in that a driving force is transmitted to the first conveying member and the second conveying member from the same driving source.

8. The powder conveying device according to any one of claims 1 to 7, A powder conveying device, characterized in that the rotation speed of the second conveying member is faster than the rotation speed of the first conveying member.

9. an imaging means for forming a toner image; an image forming apparatus including a toner transport device that transports toner, 9. An image forming apparatus, comprising: the powder transport device according to claim 1 as the toner transport device.

Images