Powder recovery container and image forming apparatus

Abstract

To efficiently recover powder into a space in a container.SOLUTION: A powder recovery container is provided with a contain body 31 into which waste toner T (powder) flowing in from a recovery port 31c is recovered, and a conveying screw 32 having a screw part 32b wound around a shaft part 32a extending in an axial direction, driven to rotate in a predetermined direction, and conveying the waste toner T flowing into the container body 31 toward an end in the axial direction. The conveying screw 32 is provided with at least one non-screw part W around which the screw part is not wound, at a position of the shaft part 32a between the recovery port 31c and the end in the axial direction.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a powder collection container for collecting powders such as waste toner, and an image forming apparatus such as a copier, a printer, a facsimile machine, or a multifunction machine equipped with the same.

Background Art

[0002] Conventionally, in image forming apparatuses such as copiers and printers, those provided with a powder collection container such as a waste toner collection container are widely known (see, for example, Patent Document 1). And, in such a powder collection container, many are used which are provided with a conveying screw for axially conveying the powder flowing in from the collection port.

[0003] On the other hand, Patent Document 1 discloses a technique for determining the shape of the ceiling portion of a waste toner collection container in consideration of the angle of repose of waste toner for the purpose of collecting waste toner in the collection space without waste.

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional powder collection container, when the powder flowing in from the collection port and conveyed to the axial end by the conveying screw stays in a large amount at the end in the width direction, there is still a sufficient space for collecting the powder in other parts, but it cannot be collected any more. Therefore, the collection space in the container has not been efficiently utilized.

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a powder collection container and an image forming apparatus in which powder is efficiently collected in the space in the container.

Means for Solving the Problems

[0006] The powder recovery container in this invention comprises a container body from which powder flowing in from a recovery port is recovered, and a conveying screw provided on a shaft extending in the axial direction, which is rotationally driven in a predetermined direction to convey the powder flowing into the container body toward the axial end, A fullness detection sensor is installed on the upper part of the axial end of the container body, which is the axial end, and when it detects that powder is present at that position, it indicates that the inside of the container body is full of powder. The conveying screw is provided with at least one non-screw portion where the screw portion is not wound, located at the position of the shaft portion between the recovery port and the axial end. Furthermore, when H1 is the height from the bottom surface to the top surface inside the container body, and H2 is the height from the bottom surface to the center of the shaft, the relationship H2 / H1 ≤ 1 / 2 holds true. It is. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a powder recovery container and an image forming apparatus in which powder is efficiently recovered into the space inside the container. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention. [Figure 2] This figure shows the process cartridge and its vicinity. [Figure 3] This is a cross-sectional view showing the waste toner collection container installed in the main body of the image forming apparatus, viewed from the axial direction. [Figure 4] This diagram shows the state of a small amount of waste toner collected inside the waste toner collection container. [Figure 5] This figure shows the state after waste toner has been collected inside the waste toner collection container shown in Figure 4. [Figure 6] This figure shows the state after waste toner has been collected inside the waste toner collection container shown in Figure 5. [Figure 7] This figure shows the state after waste toner has been collected inside the waste toner collection container shown in Figure 6. [Figure 8] This figure shows the state after waste toner has been collected inside the waste toner collection container shown in Figure 7. [Figure 9] This figure shows the waste toner collection container in Figure 8, now completely full after more waste toner has been collected inside. [Figure 10]This figure shows a comparison example of a waste toner collection container that has been filled to capacity with waste toner. [Figure 11] This figure shows a waste toner collection container as an example of modification 1. [Figure 12] This figure shows a waste toner collection container as a variation 2. [Figure 13] This figure shows a waste toner collection container as a third variation. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments for carrying out this invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be simplified or omitted as appropriate.

[0010] First, the overall configuration and operation of the image forming apparatus 100 will be explained using Figures 1 and 2. As shown in Figure 1, an intermediate transfer belt device 15 is installed in the center of the image forming apparatus body 100. Process cartridges 6Y, 6M, 6C, and 6K corresponding to each color (yellow, magenta, cyan, and black) are arranged side by side opposite the intermediate transfer belt 8 of the intermediate transfer belt device 15. Below the intermediate transfer belt device 15, a waste toner collection container 30 is installed as a powder collection container. The waste toner collection container 30 collects untransferred toner that has been collected by the cleaning devices 2Y, 2M, 2C, 2K, and 16 during the image forming operation, and recovers it as waste toner (powder) via the waste toner transport unit 40 (see Figure 3).

[0011] Referring to FIG. 2, the process cartridge 6Y corresponding to yellow includes a photosensitive drum 1Y as an image carrier, a charging device 4Y (charging roller) disposed around the photosensitive drum 1Y, a developing device 5Y, and a cleaning device 2Y, which are configured to be detachable (replaceable) from the image forming apparatus main body 100 as one unit. And on the photosensitive drum 1Y, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed, and a yellow image is formed on the photosensitive drum 1Y. That is, the process cartridge 6Y constitutes an image forming unit together with a primary transfer roller 9Y (primary transfer device) and the like.

[0012] Note that the other three process cartridges 6M, 6C, 6K (image forming units) are configured substantially the same as the process cartridge 6Y (image forming unit) corresponding to yellow, except that the color of the toner used is different, and images corresponding to their respective toner colors are formed. Hereinafter, the description of the other three process cartridges 6M, 6C, 6K (image forming units) will be appropriately omitted, and only the description of the process cartridge 6Y (image forming unit) corresponding to yellow will be given.

[0013] Referring to FIG. 2, the photosensitive drum 1Y is rotationally driven clockwise by a main motor. And at the position of the charging device 4Y (charging roller), the surface of the photosensitive drum 1Y is uniformly charged (this is the charging process). Thereafter, the surface of the photosensitive drum 1Y reaches the irradiation position of the exposure light emitted from the exposure unit 7Y (light writing head), and an electrostatic latent image corresponding to yellow is formed by exposure scanning at this position (this is the exposure process).

[0014] Thereafter, the surface of the photosensitive drum 1Y reaches the position facing the developing device 5Y, and the electrostatic latent image is developed at this position to form a yellow toner image (this is the developing process). Thereafter, the surface of the photoreceptor drum 1Y reaches the position facing the intermediate transfer belt 8 and the primary transfer roller 9Y, and at this position, the toner image on the photoreceptor drum 1Y is transferred onto the intermediate transfer belt 8 (this is the primary transfer process). At this time, a small amount of untransferred toner remains on the photoreceptor drum 1Y.

[0015] Thereafter, the surface of the photoreceptor drum 1Y reaches the position facing the cleaning device 2Y, and at this position, the untransferred toner remaining on the photoreceptor drum 1Y is recovered into the cleaning device 2Y by the cleaning blade 2a (this is the cleaning process). Note that the untransferred toner recovered inside the cleaning device 2Y is conveyed by the conveying coil 2Ya to the front side in the direction perpendicular to the paper surface of FIGS. 1 and 2, and then is stored (recovered) as waste toner inside the waste toner recovery container 30 (see FIG. 3) serving as a powder recovery container via the waste toner conveying section 40 (conveying path). Finally, the surface of the photoreceptor drum 1Y reaches the position facing the charge removal device (not shown), and at this position, the residual potential on the photoreceptor drum 1 is removed. Thus, a series of image forming processes performed on the photoreceptor drum 1Y are completed.

[0016] Note that the above-described image forming process is also performed in the same manner for the other process cartridges 6M, 6C, 6K (image forming units) as for the yellow process cartridge 6Y (image forming unit). That is, exposure light based on the image information is irradiated from the exposure unit disposed above the image forming unit onto the photoreceptor drums of the respective process cartridges 6M, 6C, 6K. Thereafter, the toner images of respective colors formed on each photoreceptor drum after the developing process are transferred and overlapped onto the intermediate transfer belt 8. Thus, a color image is formed on the intermediate transfer belt 8.

[0017] Here, the intermediate transfer belt device 15, referring to Figure 1, consists of an intermediate transfer belt 8, four primary transfer rollers 9Y (see Figure 2), a drive roller, a driven roller, etc. The intermediate transfer belt 8 is stretched and supported by the drive roller, the driven roller and the primary transfer roller, and is moved endlessly in the direction of the arrow in Figure 1 (counterclockwise) by the rotational drive of the drive roller.

[0018] The primary transfer roller 9Y sandwiches the intermediate transfer belt 8 between itself and the photoreceptor drum 1Y to form a primary transfer nip. A transfer voltage (transfer bias) opposite to the polarity of the toner is then applied to the primary transfer roller 9Y. The intermediate transfer belt 8 then travels in the direction of the arrow, sequentially passing through the primary transfer nips of each primary transfer roller (9Y). In this way, the toner images of each color on each photoreceptor drum (1Y) are superimposed onto the intermediate transfer belt 8 and primary transferred.

[0019] Subsequently, the intermediate transfer belt 8, on which the toner images of each color have been superimposed, reaches a position opposite the secondary transfer roller 19 (secondary transfer device). At this position, the drive roller (secondary transfer opposing roller) sandwiches the intermediate transfer belt 8 between itself and the secondary transfer roller 19, forming a secondary transfer nip. The four toner images formed on the intermediate transfer belt 8 are then transferred onto a sheet P, such as paper, which has been transported to the position of this secondary transfer nip (this is the secondary transfer process). At this time, untransferred toner remains on the intermediate transfer belt 8 that has not been transferred to the sheet P.

[0020] Subsequently, the intermediate transfer belt 8 reaches the position of the cleaning device 16 for the intermediate transfer belt. At this position, the untransferred toner on the intermediate transfer belt 8 is mechanically removed by an intermediate transfer cleaning blade that presses against the intermediate transfer belt 8. Here, the intermediate transfer cleaning blade is a roughly plate-shaped member made of an elastic material such as urethane rubber, and it contacts the intermediate transfer belt 8 with a predetermined contact pressure and contact angle. The untransferred toner collected inside the cleaning device 16 for the intermediate transfer belt is transported by a transport coil to the front side in the vertical direction of the paper in Figures 1 and 2, similar to the untransferred toner collected inside the cleaning devices 2Y, 2M, 2C, and 2K for the photoreceptor drum, and is then collected as waste toner (powder) inside the waste toner collection container 30 (see Figure 3) via the waste toner transport section 40. The waste toner collection container 30 (powder collection container) will be explained in detail later using Figures 3 to 9, etc. Thus, the series of transfer processes performed on the intermediate transfer belt 8 are completed.

[0021] Referring to Figure 1, the sheet P that is transported to the secondary transfer nip position is transported from the paper feed device 26 located below the main body of the apparatus 100, via the paper feed roller 27 and the pair of registration rollers 28 (timing roller pair). More specifically, the paper feeder 26 stores multiple sheets P of paper or the like stacked together. When the paper feed roller 27 is driven to rotate counterclockwise in Figure 1, the top sheet P is fed towards the space between the registration rollers 28.

[0022] The sheet P, transported to the register roller pair 28, temporarily stops at the position of the roller nip of the register roller pair 28, where the rotational drive has been stopped. Then, in time with the color image on the intermediate transfer belt 8, the register roller pair 28 is driven to rotate again, and the sheet P is transported toward the secondary transfer nip. In this way, the desired color image is transferred onto the sheet P.

[0023] Subsequently, the sheet P onto which the color image has been transferred at the secondary transfer nip is transported to the fixing device 20 (fixing nip). At this position, the heat and pressure from the fixing belt 21 (fixing member) and the pressure roller 22 (pressure member) fix the color image (toner image) transferred to the surface onto the sheet P (this is the fixing process). Subsequently, the sheet P is discharged from the device by the paper discharge roller pair. The sheet P discharged from the device by the paper discharge roller pair is sequentially stacked on the stacking section (main body cover 110) as output images. Thus, the series of image formation processes in the image forming apparatus are completed.

[0024] Next, Figure 2 will detail the image-forming section of the image-forming apparatus. As shown in Figure 2, the process cartridge 6Y consists of a photoreceptor drum 1Y (image carrier), a charging device 4Y (charging roller), a developing device 5Y, a cleaning device 2Y, and so on. The photoreceptor drum 1Y, which serves as the image carrier, is a negatively charged organic photoreceptor and is driven to rotate clockwise in Figure 2 by receiving driving force from the main motor installed on the device body 100 side.

[0025] The charging device 4Y (charging roller) is an elastic roller member formed on a metal core, comprising a medium-resistance foamed urethane layer containing urethane resin, carbon black as conductive particles, a sulfurizing agent, a foaming agent, and the like. The cleaning device 2Y is equipped with a cleaning blade 2a that slides against the photoreceptor drum 1Y, and mechanically removes and recovers untransferred toner from the photoreceptor drum 1Y. The cleaning blade 2a is a substantially plate-shaped member made of an elastic material such as urethane rubber, and contacts the photoreceptor drum 1Y at a predetermined contact pressure and contact angle.

[0026] The developing device 5Y is configured such that a developing roller 51, acting as a developer carrier, is in contact with the photoreceptor drum 1Y, and a developing region is formed between the two components 1Y and 51 (at the contact point). The developing device 5Y contains toner (a non-magnetic or magnetic one-component developer) as the developer. The developing device 5Y then develops the electrostatic latent image formed on the photoreceptor drum 1Y (forming a toner image). The developing unit 5Y consists of a developing roller 51, a supply roller 53, a doctor blade 52, developing transport screws 54 and 55, etc. A toner container 60 is also detachably mounted on top of the developing unit 5Y for supplying new toner to the unit as needed.

[0027] The characteristic configuration and operation of the waste toner collection container 30, which serves as a powder collection container in this embodiment, will be described in detail below. Referring to Figure 1, in this embodiment, the waste toner collection container 30, which serves as a powder collection container, is located below the intermediate transfer belt device 15 in the image forming apparatus body 100, and is positioned on the front side of the image forming apparatus body 100 (the front side in the vertical direction of the paper in Figure 1). The waste toner collection container 30 is a powder collection container capable of collecting waste toner in powder form. In this embodiment, the waste toner collection container 30 is configured to be detachable from the image forming apparatus body 100 (or the waste toner transport unit 40 shown in Figure 3), and is replaced with a new (empty) one when the inside of the waste toner collection container 30 becomes full of waste toner (when the fullness detection sensor 35 shown in Figure 3, etc., detects that there is waste toner in that position). Specifically, in this embodiment, the waste toner collection container 30 is replaced by opening and closing the main body door of the image forming apparatus body 100 (located on the left side in Figure 1), which is an attachment and detachment operation in the width direction (left and right direction in Figures 1 and 3, and in the axial direction). The position of the waste toner collection container 30 and the direction in which it is attached and detached are not limited to those of this embodiment.

[0028] Referring to Figure 3, etc., the waste toner collection container 30 (powder collection container) is a box-shaped container formed so that its longitudinal direction is in the width direction (the left-right direction in Figures 3 and 4, which is the axial direction of the transport screw 32 described later). As shown in Figure 3, the container body 31, which serves as the housing for the waste toner collection container 30, is molded into a bottle shape, for example by blow molding, and has a roughly rectangular space (collection space) formed inside. A collection opening 31c is formed on the top surface of the container body 31. This collection opening 31c is connected to and disconnected from the waste toner transport section 40, which is fixed to the image forming apparatus body 100, in conjunction with the attachment and detachment of the waste toner collection container 30 to the image forming apparatus body 100.

[0029] Referring to Figure 3, the waste toner transport section 40 is a transport path through which untransferred toner (powder) collected by multiple cleaning devices is transported as waste toner toward the waste toner collection container 30. Inside the waste toner transport section 40 is a waste toner transport screw 41 that rotates in a predetermined direction to transport the waste toner from left to right in Figure 3. In the waste toner transport section 40, an outlet is formed at the upstream end for untransferred toner collected by the black cleaning device 2K to be discharged, an outlet is formed downstream for untransferred toner collected by the cyan cleaning device 2C to be discharged, an outlet is formed downstream for untransferred toner collected by the magenta cleaning device 2M to be discharged, an outlet is formed downstream for untransferred toner collected by the yellow cleaning device 2Y to be discharged, and an outlet is formed at the downstream end for untransferred toner collected by the intermediate transfer belt cleaning device 16 to be discharged.

[0030] Then, with a portion of the waste toner transport section 40 (transport path) connected to the waste toner collection container 30 via the collection port 31c (as shown in Figure 3), the toner (untransferred toner, waste toner) collected by the five cleaning devices 2Y, 2M, 2C, 2K, and 16 respectively is discharged from the discharge port 40a of the waste toner transport section 40 and collected (stored) inside the waste toner collection container 30. In detail, the untransferred toner collected by the five cleaning devices 2Y, 2M, 2C, 2K, and 16 is discharged from their respective outlets to the waste toner transport unit 40, then transported by the waste toner transport screw 41 to the position of outlet 40a, and finally falls by gravity in the direction of the black arrow and is collected as waste toner T inside the waste toner collection container 30 (container body 31).

[0031] On the other hand, referring to Figure 3, the waste toner collection container 30 is equipped with a transport screw 32 (screw member) that transports the waste toner T (powder) that has flowed into the container body 31 from the collection port 31c to the axial end (the left end in Figures 3 to 9). The transport screw 32 consists of a shaft portion 32a and a screw portion 32b that is spirally wound around the shaft portion 32a, and is a screw member made of metal or resin material. A driven gear 36 (or driven coupling) is installed on the rear side of the transport screw 32 in the mounting direction (the right side in Figure 3). Although not shown in the illustration, this driven gear 36 (or driven coupling) is fitted into a drive gear (or drive coupling) installed on the motor shaft of the motor (fixed to the device body 100). Then, receiving driving force from the motor, the transport screw 32 is rotated, and the waste toner T that has flowed into the container body 31 is transported in the direction of the white arrow in Figure 3.

[0032] More specifically, first, in an empty waste toner collection container 30, the waste toner T flowing in from the collection port 31c accumulates at the bottom below the collection port 31c. When the height of the accumulated waste toner T reaches the position of the transport screw 32, the waste toner T is transported by the transport screw 32 in the direction of the white arrow. As the collection of waste toner T progresses, when the fullness detection sensor 35 (for example, a piezoelectric sensor) installed at the axial end detects the waste toner T, the container body 31 is considered full, and a message prompting the replacement of the waste toner collection container 30 is displayed on the operation display panel 95 (see Figure 1) of the image forming apparatus body 100. The behavior of the waste toner T from the time it flows into the empty waste toner collection container 30 until the waste toner collection container 30 becomes full will be explained in detail later using Figures 4 to 9.

[0033] As described above, the waste toner collection container 30 (powder collection container) in this embodiment is provided with a container body 31 from which waste toner T (powder) flowing in from the collection port 31c is collected, and a transport screw 32 (a screw portion 32b is wound around a shaft portion 32a that extends in the axial direction) that is rotated in a predetermined direction to transport the waste toner (powder) that has flowed into the container body 31 toward the axial end (the left end in Figures 3 to 9). In particular, in this embodiment, the waste toner collection container 30 is positioned such that, as shown in Figure 3, the transport screw 32 is located away from the ceiling and relatively close to the bottom surface (at a height H2 from the bottom surface) within the container body 31, due to layout constraints inside the image forming apparatus body 100 and cost reasons for sharing the drive source for rotating the transport screw 32 with the drive source for rotating other components (for example, the paper feed roller 27).

[0034] In this embodiment, the collection port 31c is formed on the upper part of the container body 31 on the axial end side (the right end in Figure 3) relative to the axial end side which is the axial end. However, as shown in Figure 3, the collection port 31c is not limited to the position of the top of the container body 31, but can be located anywhere that allows waste toner T to flow into the inside of the container body 31, for example, on the side wall near the top.

[0035] Here, as shown in Figure 3 and other figures, the conveying screw 32 in this embodiment has at least one non-screw portion W where the screw portion 32b is not wound, located at the position of the shaft portion 32a between the recovery port 31c and the axial end. Specifically, the conveying screw 32 has a non-screw section W consisting only of the shaft portion 32a, located at a distance N downstream from the recovery port 31c in the conveying direction, with a length M. In other words, the conveying screw 32 does not have a screw portion 32b throughout its entire axial length within the container body 31, but rather has a non-screw section W in a part of its axial direction (downstream from the recovery port 31c in the conveying direction, and in the axial center upstream of the inner wall surface of the downstream end).

[0036] By providing a non-screw section W in part of the transport screw 32 in this way, the waste toner T is not directly transported sequentially to the axial end (downstream end in the transport direction) by the transport screw 32. Instead, as shown in Figure 7, a buffer section (a pile of waste toner T) is formed at the location of the non-screw section W, and the toner is then transported to the axial end (downstream end in the transport direction) while maintaining the formation of the buffer section. Finally, as shown in Figure 9, when piles of waste toner T reaching the ceiling are formed at the axial end (downstream end in the transport direction) where the full-capacity detection sensor 35 is installed, and at the location of the non-screw section W, the full-capacity detection sensor 35 detects that the tank is full. Therefore, in the comparative example shown in Figure 10, the waste toner collection container 130 (equipped with a transport screw 132 that has a screw section along its entire axial length) is found to be full when piles of waste toner T are formed only at the axial ends, and the fullness detection sensor 35 detects that it is full. In contrast, in this embodiment, piles of waste toner T are formed even at the non-screw section W, so the collection space within the container body 31 is effectively utilized (resulting in a larger amount of waste toner T being collected). In other words, waste toner is efficiently collected within the space of the waste toner collection container 30. In particular, in this embodiment, the waste toner collection container 30 is useful because, as explained earlier, the transport screw 32 is installed at a low position inside the container due to layout constraints and the like.

[0037] Furthermore, in this embodiment, since the full-capacity detection sensor 35 is installed on the upper part of the axial end (the downstream end in the transport direction) (which is the ceiling surface in this embodiment), full-capacity detection occurs when a pile of waste toner T is formed that eventually reaches the position of the full-capacity detection sensor 35. In this case, as shown in Figure 10 as a comparative example of a waste toner collection container 130, if a pile of waste toner T is formed only at the widthwise end, the load on the axial end of the transport screw 132 due to the waste toner T becomes locally larger than the load on other parts, making the transport screw 132 more prone to rotational twisting. If the strength of the transport screw 132 against this twisting is insufficient, there is a possibility that the transport screw 132 may break or break before fullness detection occurs. In contrast, in this embodiment, as shown in Figure 9, piles of waste toner T are formed not only at the widthwise ends but also in the non-screw portion W. Therefore, twisting of the transport screw 132 due to the magnitude of the localized load described above is less likely to occur, and problems such as breakage of the transport screw 132 are also reduced. In this embodiment, the full-capacity detection sensor 35 is installed on the ceiling surface at the axial end of the container body 31. However, the position of the full-capacity detection sensor 35 is not limited to this. For example, the full-capacity detection sensor 35 can also be installed in a position closer to the upper part of the side wall of the container body 31.

[0038] Furthermore, in cases where a pile of waste toner T is formed only at the widthwise end, as in the waste toner collection container 130 shown in Figure 10 as a comparative example, the waste toner T is directly transported by the transport screw 132 toward the pile of waste toner T. As a result, the pile of waste toner T is pressed against the inner wall surface at the widthwise end, which makes it easier for abnormal noises (squeaking noises) to occur and increases the driving torque of the transport screw 32. In contrast, in this embodiment, as shown in Figure 9, piles of waste toner T are formed not only at the widthwise ends but also in the non-screw section W. Therefore, the piles of waste toner T in the non-screw section W act as a buffer, reducing the force with which the piles of waste toner T are pressed against the inner wall surface at the widthwise ends. As a result, the aforementioned abnormal noise is less likely to occur, and the driving torque of the transport screw 32 is also reduced.

[0039] Here, referring to Figures 3 and 7, in this embodiment, the waste toner collection container 30 has a height of H1 from the bottom to the top of the container body 31, a height of H2 from the bottom to the center of the shaft portion 32a (the rotation center of the transport screw 32), and a length of M in the axial direction (left-right direction in Figures 3 and 7) of the non-screw portion W, and the angle of repose of the waste toner T (powder) is θ. (H1-H2) / tanθ≦M …(Formula 1) It is structured in such a way that the following relationship is established. The "angle of repose θ" of waste toner T (powder) is defined as the maximum slope angle of a stable pile of waste toner T (powder) that does not spontaneously collapse during the accumulation process. In other words, when waste toner T accumulates beyond the angle of repose θ, the pile will collapse even without any external force acting upon it.

[0040] By configuring the container to satisfy the above (Equation 1), in the process in which the amount of waste toner T collected in the waste toner collection container 30 gradually increases and eventually reaches a full state, first, as shown in Figure 7, a pile of waste toner T (buffer) is formed at the non-screw section W, reaching the ceiling surface, and then, while maintaining this pile of waste toner T (buffer), the waste toner T is transported downstream in the transport direction relative to the non-screw section W. In other words, by setting the length M of the non-screw section W to be sufficiently long, a sufficiently high peak (buffer section) can be formed that reaches the ceiling surface at the location of the non-screw section W. As a result, as shown in Figure 9, the amount of waste toner recovered when full tank is detected can be increased. In particular, as explained earlier, in this embodiment, the transport screw 32 is installed at a low position inside the waste toner collection container 30 due to layout constraints, but even in such a case, it is possible to increase the amount of waste toner collected when full is detected. In this embodiment, the relationship between heights H1 and H2 described above is configured such that H2 / H1 ≤ 1 / 2 holds true. Furthermore, if the top or bottom surface of the container body 31 has irregularities, the heights H1 and H2 mentioned above shall be based on the lowest point of the bottom surface and the highest point of the top surface.

[0041] Furthermore, referring to Figures 3 and 7, in this embodiment, when the distance between the axial end of the non-screw portion W on the side closer to the recovery port 31c and the axial end of the recovery port 31c on the side closer to the non-screw portion W is N, M≦N…(Formula 2) It is preferable to configure the system so that the following relationship is established. With this configuration, even if the pile of waste toner T formed at the non-screw section W forms an inclined surface with an angle of repose θ on the upstream side in the transport direction, the distance to the collection port 31c is set to be sufficiently long, thus reducing the problem of waste toner T leaking out (backflowing) from the collection port 31c to the outside. Furthermore, if the conveying screw 32 is provided with multiple non-screw sections W, the above (Equation 2) becomes a relational expression for the non-screw section W located on the uppermost side among the multiple non-screw sections W.

[0042] The behavior of the waste toner T from the time waste toner begins flowing into the empty waste toner collection container 30 until the waste toner collection container 30 becomes full will be explained below using Figures 4 to 9. First, when waste toner T begins to flow into the empty waste toner collection container 30, as shown in Figure 4, the waste toner T accumulates in a roughly conical shape with an angle of repose θ directly below the collection port 31c. Subsequently, as the inflow of waste toner T continues and the waste toner T accumulates up to the position of the transport screw 32 (approximately height H2), as shown in Figure 5, the waste toner T is transported to the left in Figure 5 by the transport screw 32 (screw section 32b) while maintaining the angle of repose θ at the downstream end in the transport direction. Then, as the inflow of waste toner T continues and the waste toner T reaches the position of the non-screw section W, since transport by the screw section does not occur at that position, as shown in Figure 6, the waste toner T forms a pile of waste toner T, being pushed up by the waste toner T being transported from the upstream side while maintaining the angle of repose θ at the downstream end. As the inflow of waste toner T continues, as shown in Figure 7, the waste toner T is pushed up by the waste toner T being transported from the upstream side, while maintaining the angle of repose θ at the downstream end, forming a pile of waste toner T that reaches the ceiling surface of the container body 31. Subsequently, as the inflow of waste toner T continues, as shown in Figure 8, the waste toner T maintains a pile of waste toner T (buffer section) in the non-screw section W, and is pushed into the waste toner T being transported from the upstream side. The waste toner T on the downstream side in the transport direction is then transported to the left in Figure 8 by the transport screw 32 (screw section 32b). As the inflow of waste toner T continues, the waste toner T reaches the inner wall surface of the axial end (downstream end in the transport direction) while maintaining a pile of waste toner T (buffer section) in the non-screw section W. Eventually, as shown in Figure 9, a pile of waste toner T is formed at the axial end (downstream end in the transport direction) that reaches the ceiling surface of the container body 31. When this pile of waste toner T reaches the full-capacity detection sensor 35, the full-capacity detection sensor 35 detects that the container body 31 is full.

[0043] <Example 1> As shown in Figure 11, in the waste toner collection container 30 of the modified example 1, the transport screw 32 is provided with a second non-screw portion Z at its axial end (downstream end in the transport direction) where the screw portion is not wound. More specifically, in the modified example 1, the conveying screw 32 has a non-screw portion W (first non-screw portion) formed in the axial center, and a second non-screw portion Z formed at the axial end. By providing the second non-screw section Z in this way, the transport force of the waste toner T at that position is reduced. As a result, the axial range of the pile of waste toner T at the axial end when full is detected is wider compared to the one shown in Figure 9. Therefore, the amount of waste toner recovered increases accordingly. Thus, in this modified example 1 as well, the waste toner T can be efficiently collected in the space within the waste toner collection container 30.

[0044] <Modification 2> As shown in Figure 12, in the waste toner collection container 30 of the modified example 2, the transport screw 32 has two non-screw sections W1 and W2 where the screw section 32b is not wound, located at the position of the shaft section 32a between the collection port 31c and the axial end. With this configuration, two non-screw sections W1 and W2 can each form piles (buffer sections) of waste toner T, which increases the amount of waste toner recovered. Thus, in this modified example 2 as well, the waste toner T can be efficiently collected in the space within the waste toner collection container 30. In addition, it is preferable that the modified example 2 also be configured to satisfy the equations (Equation 1) and (Equation 2) described above. Furthermore, in the modified example 2, three or more non-screw sections can be provided.

[0045] <Variation 3> As shown in Figure 13, in the modified example 3, the waste toner collection container 30 has a collection port 31c formed on the ceiling surface of the container body 31, which is located in the axial center, rather than on the other axial end (right side of the figure) as in Figure 3. Furthermore, in the modified example 3, the transport screw 32 is formed such that the winding direction of the screw portion 32b located at one axial end A1 and the winding direction of the screw portion 32b located at the other axial end A2 are opposite in order to transport the waste toner T that has flowed in from the collection port 31c in the axial center toward both ends in the direction of the white arrows. That is, the transport screw 32 is rotated in a predetermined direction to transport the waste toner T that has flowed into the axial center toward both the one axial end A1 and the other axial end A2. Even with this configuration, by forming non-screw sections W on both the axial end A1 and the axial end A2 of the transport screw 32, the waste toner T can be efficiently collected into the space within the waste toner collection container 30. In addition, it is preferable that the modified example 3 also be configured to satisfy the equations (Equation 1) and (Equation 2) described above. Furthermore, in the modified example 3, the full-capacity detection sensor 35 can be installed on the ceiling surface at the end of the axial end A1, or on the ceiling surface at the end of the other axial end A2.

[0046] As described above, the waste toner collection container 30 (powder collection container) in this embodiment is provided with a container body 31 from which waste toner T (powder) flowing in from the collection port 31c is collected, and a transport screw 32 on which a screw portion 32b is wound around an axially extending shaft portion 32a and is rotated in a predetermined direction to transport the waste toner T flowing into the container body 31 toward the axial end. The transport screw 32 is provided with at least one non-screw portion W on which the screw portion is not wound, located at the position of the shaft portion 32a between the collection port 31c and the axial end. This allows for the efficient collection of waste toner T into the space within the waste toner collection container 30.

[0047] In this embodiment, the present invention was applied to an image forming apparatus 100 configured such that untransferred toner collected in multiple cleaning devices 2Y, 2M, 2C, 2K, and 16 is transported to a waste toner collection container 30 via a waste toner transport unit 40 (transport path). However, the application of the present invention is not limited to this, and it can naturally be applied to an image forming apparatus configured such that untransferred toner collected in a single cleaning device is transported to a waste toner collection container via a transport path. Furthermore, in this embodiment, the present invention was applied to a waste toner collection container 30, which is a powder collection container from which waste toner in powder form is collected. However, the application of the present invention is not limited to this, and the present invention can be applied to all powder collection containers from which powder is collected (for example, a powder collection container from which a two-component developer consisting of toner in powder form and a carrier is collected). Furthermore, the same effects as those of this embodiment can be obtained in such cases as well.

[0048] It is clear that the present invention is not limited to this embodiment, and that this embodiment can be modified as appropriate within the scope of the technical concept of the present invention, in addition to what is suggested here. Furthermore, the number, position, shape, etc. of the constituent members are not limited to this embodiment, and can be set to a number, position, shape, etc. that is suitable for carrying out the present invention.

[0049] Furthermore, the embodiments of the present invention can also be, for example, combinations of appendices 1 to 10 as follows. (Note 1) The container body from which the powder flowing in from the collection port is collected, A conveying screw has a screw portion wound around a shaft that extends in the axial direction, and is rotationally driven in a predetermined direction to convey the powder that has flowed into the container body toward the axial end. Equipped with, The powder recovery container is characterized in that the conveying screw has at least one non-screw portion where the screw portion is not wound around it, located at the position of the shaft portion between the recovery port and the axial end. (Note 2) When H1 is the height from the bottom to the top of the container body, H2 is the height from the bottom to the center of the shaft, M is the axial length of the non-screw portion, and θ is the angle of repose of the powder, (H1-H2) / tanθ≦M The powder recovery container described in Appendix 1, characterized in that the following relationship is established. (Note 3) When the distance between the axial end of the non-screw portion closest to the recovery port and the axial end of the recovery port closest to the non-screw portion is N, M≦N The powder recovery container described in Appendix 2, characterized in that the following relationship is established. (Note 4) The powder recovery container according to any one of the appendices 1 to 3, characterized in that the conveying screw is provided with a second non-screw portion at its axial end, where the screw portion is not wound around it. (Note 5) The powder recovery container according to any one of the appendices 1 to 4, characterized in that the recovery port is formed on the upper part of the container body on the axial end side with respect to the axial end side which is the axial end. (Note 6) The powder collection container is a waste toner collection container capable of collecting waste toner as a powder, as described in any of Appendix 1 to Appendix 5. (Note 7) An image forming apparatus characterized by being equipped with a powder recovery container as described in any of Appendix 1 to Appendix 6. [Explanation of symbols]

[0050] 2Y, 2M, 2C, 2K cleaning equipment 16 Cleaning device (cleaning device for intermediate transfer belt), 30. Waste toner collection container (powder collection container), 31 Container body (case), 31c Collection port, 32 Conveyor screw (rotating component), 32a Shaft section, 32b Screw section, 100 Image forming apparatus (image forming apparatus main unit), T Waste toner (powder), W, W1, W2 non-screw section, Z Second non-screw section. [Prior art documents] [Patent Documents]

[0051] [Patent Document 1] Patent No. 6136695

Claims

1. The container body from which the powder flowing in from the collection port is collected, A conveying screw is provided on a shaft that extends in the axial direction, and is rotationally driven in a predetermined direction to convey the powder that has flowed into the container body toward the axial end. A fullness detection sensor is installed on the upper part of the axial end of the container body, which is the axial end, and when it detects that powder is present at that position, it indicates that the inside of the container body is full of powder. Equipped with, The conveying screw is provided with at least one non-screw portion where the screw portion is not wound, located at the position of the shaft between the recovery port and the axial end. When H1 is the height from the bottom surface to the top surface inside the container body, and H2 is the height from the bottom surface to the center of the shaft, H2 / H1 ≤ 1 / 2 A powder recovery container characterized by the establishment of the following relationship.

2. When the axial length of the non-screw portion is M and the angle of repose of the powder is θ, (H1-H2) / tanθ≦M The powder recovery container according to claim 1, characterized in that the following relationship is established.

3. When the distance between the axial end of the non-screw portion closest to the recovery port and the axial end of the recovery port closest to the non-screw portion is N, M≦N The powder recovery container according to claim 2, characterized in that the following relationship is established.

4. The powder recovery container according to claim 1 or 2, characterized in that the conveying screw is provided with a second non-screw portion at its axial end, where no screw portion is provided.

5. The powder recovery container according to claim 1 or 2, characterized in that the recovery port is formed on the upper part of the container body on the other end side in the axial direction relative to the one end side in the axial direction.

6. The powder collection container is characterized in that it is a waste toner collection container capable of collecting waste toner as a powder, as described in claim 1 or 2.

7. The collection port is formed on the ceiling surface, The full-capacity detection sensor is installed on the ceiling surface, The powder recovery container according to claim 1 or 2, characterized in that only one conveying screw is installed.

8. An image forming apparatus characterized by comprising a powder recovery container according to claim 1 or claim 2.

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