Image forming device

Abstract

To effectively remove paper powder from a plurality of paper feeding parts without increasing a size and cost of an image forming device.SOLUTION: A paper powder recovery unit 17 is provided on a downstream of a paper feeding cassette 10 and a multi-tray 11 in a paper conveyance direction and on an upstream of a junction part 311, and has: a paper powder recovery roller 201 that, when a paper sheet 12a is fed, comes into contact with the paper sheet 12a and recovers paper powder while rotating in a direction of an arrow 404, and when the paper sheet 12b is fed, comes into contact with the paper sheet 12b and recovers paper powder while rotating in a direction of an arrow 504; a guide member 312a that faces the paper powder recovery roller 201 and forms a part of a first path together with the paper powder recovery roller 201; and a guide member 312b that faces the paper powder recovery roller 201 and forms a part of a second path together with the paper powder recovery roller 201.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus using electrophotography, such as a laser printer. [Background technology]

[0002] An image forming apparatus such as a laser printer has a plurality of paper feed units, such as a paper feed cassette or a multi-purpose tray, on which recording materials for printing are stacked, and a separation pad or a separation roller as a separation means for separating sheets above one end side of the paper feed unit. In such an image forming apparatus, the paper surface is subjected to stress due to friction between sheets of paper caused by the separation of the recording materials and frictional force from the separation means, and the amount of paper dust on the paper increases in some parts. If such paper dust gets mixed into the toner during the image formation process, there is a problem that it leads to a decrease in image quality. For this reason, a paper dust collecting roller having a width approximately the same as the width of the separation means is disposed downstream of the separation means in the paper transport direction of each paper feed unit, and the paper dust generated on the paper is removed before the paper is transported to the image forming unit (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-041652 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional example, it is necessary to arrange a dedicated paper dust collection roller for each of the multiple paper feed units. For example, in the conventional image forming apparatus, the surface (hereinafter referred to as the separation surface side) with which the separation pad contacts is different between the paper fed from the paper feed tray and the paper fed from the multi-purpose tray. Therefore, it is necessary to arrange a dedicated paper dust collection roller that contacts the separation surface side of the paper fed from each paper feed unit and collects the paper dust. For this reason, a space is required in multiple places to arrange the paper dust collection roller and the parts associated with it, which causes a problem of the device becoming larger. Also, in order to efficiently collect paper dust, it is necessary to make the paper dust collection roller out of, for example, a fluorine-based resin that has high charging performance. However, such materials are expensive, and there is a problem that increasing the number of paper dust collection rollers increases the parts cost of the image forming apparatus.

[0005] The present invention has been made under these circumstances, and has an object to effectively remove paper dust from a plurality of paper feed units without increasing the size and cost of the image forming apparatus. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention has the following configuration.

[0007] (1) An image forming apparatus including a first paper feed section on which a first recording material is placed, a second paper feed section on which a second recording material is placed and which is different from the first paper feed section, and an image forming means for forming an image on the first recording material or the second recording material, the image forming apparatus further including a recovery means for recovering first paper powder adhering to the first recording material and second paper powder adhering to the second recording material, the recovery means being provided at a junction where a first path along which the first recording material is transported until it reaches the image forming means and a second path along which the second recording material is transported until it reaches the image forming means intersect, the recovery means being provided at a junction where the first paper feed section and the second paper feed section intersect a rotating body that is provided downstream of the confluence in a recording material transport direction and upstream of the junction, and that, when the first recording material is fed, comes into contact with the first recording material and rotates in a first direction to collect the first paper powder, and when the second recording material is fed, comes into contact with the second recording material and rotates in a second direction opposite to the first direction to collect the second paper powder, a first guide member that faces the rotating body and forms a part of the first path together with the rotating body, and a second guide member that faces the rotating body and forms a part of the second path together with the rotating body.

[0008] (2) An image forming apparatus comprising: a first paper feed section on which a first recording material is placed; a second paper feed section on which a second recording material is placed and which is different from the first paper feed section; an image forming means for forming an image on the first recording material or the second recording material; and a transport means having a first rotating body and a second rotating body, which sandwiches the first recording material and the second recording material between the first rotating body and the second rotating body and transports them to the image forming means, wherein the transport means has a charging member that contacts the first rotating body and charges the first rotating body by friction when the first rotating body rotates, and when a portion where a first path along which the first recording material is transported until it reaches the image forming means and a second path along which the second recording material is transported until it reaches the image forming means intersect is defined as a junction, the transport means is provided downstream of the junction in the transport direction of the recording material and upstream of the image forming means, and the first rotating body is charged by the charging member and attracts and collects paper powder by electrostatic force. Effect of the Invention

[0009] According to the present invention, it is possible to effectively remove paper dust from a plurality of paper feed units without increasing the size and cost of the image forming apparatus. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing an image forming apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing a paper dust collection unit according to a first embodiment of the present invention; [Diagram 3] FIG. 1 is a cross-sectional view showing a paper feeding operation according to the first embodiment. [Figure 4] FIG. 13 is a diagram for explaining the paper dust collecting operation from the paper feed cassette in the first embodiment. [Diagram 5] FIG. 1 is a diagram for explaining the paper dust collecting operation from the multi-tray in the first embodiment. [Figure 6] FIG. 10 is a diagram for explaining a second paper dust collecting mechanism provided in the register unit in a modified example of the first embodiment, and a diagram for explaining a state in which a paper feed unit is added. [Figure 7] FIG. 13 is a diagram illustrating the periphery of the paper dust collection unit according to the second embodiment. [Figure 8] FIG. 11 is a diagram illustrating a separating operation of the guide member according to the second embodiment. [Figure 9] FIG. 11 is a diagram illustrating the periphery of a paper dust collection unit according to a third embodiment. [Figure 10] FIG. 11 is a diagram illustrating a paper dust collection unit according to a third embodiment; FIG. 12 is a diagram illustrating a drive transmission section of an opposing roller; [Figure 11] FIG. 13 is a diagram illustrating a paper dust collection unit according to a fourth embodiment. [Figure 12] FIG. 13 is a cross-sectional view illustrating a state of the paper dust collection unit during paper transport in the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0011] [Image forming equipment] FIG. 1 is a cross-sectional view for explaining an image forming apparatus according to a first embodiment. Here, the image forming apparatus 100 according to the first embodiment is a color image forming apparatus that forms a full-color image using four color toners, namely, yellow, magenta, cyan, and black. The image forming apparatus 100 includes process cartridges 1Y, 1M, 1C, and 1K. The process cartridges 1Y, 1M, 1C, and 1K correspond to the colors yellow, magenta, cyan, and black, respectively. Hereinafter, the colors Y, M, C, and K may be omitted unless the color is particularly described. The process cartridges 1Y, 1M, 1C, and 1K each include a photosensitive drum 2Y, 2M, 2C, and 2K, a charger 3Y, 3M, 3C, and 3K, a developer 4Y, 4M, 4C, and 4K, and a toner container 5Y, 5M, 5C, and 5K. The image forming apparatus 100 includes a conveyor belt 6, transfer rollers 7Y, 7M, 7C, and 7K, a fixing unit 8, a laser scanner 9, a paper feed cassette 10 which is a first paper feed section, and a multi-tray 11 which is a second paper feed section. Paper 12a which is a first recording material is placed in the paper feed cassette 10, and paper 12b which is a second recording material is placed in the multi-tray 11. The laser scanner 9, the process cartridge 1, and the transfer roller 7 are included in the image forming section (image forming means).

[0012] Further, the paper feed cassette 10 is provided with a pickup roller 13a, a separation roller 14a, and a separation pad 15a. The multi-tray 11 is provided with a pickup roller 13b, a separation roller 14b, and a separation pad 15b. The separation roller 14a and the separation pad 15a, which are the first separation members, separate only one sheet of paper when a plurality of sheets 12a are fed from the paper feed cassette 10 in an overlapping state, and convey the separated sheet toward the downstream in the conveying direction. The separation roller 14b and the separation pad 15b, which are the second separation members, separate only one sheet of paper when a plurality of sheets 12b are fed from the multi-tray 11 in an overlapping state, and convey the separated sheet toward the downstream in the conveying direction. The image forming apparatus 100 is provided with a registration unit 16, which has a registration roller 16a and a registration facing roller 16b. The image forming apparatus 100 is also provided with a paper dust collection unit 17, which is a collection means, and will be described later. The image forming apparatus 100 also includes a plurality of pairs of discharge rollers 18, a discharge port 19, and a discharge stacking section 20. Note that the paper 12c represents a paper sheet that is being fed.

[0013] [Operation of image forming device] Next, the operation of the image forming apparatus 100 will be described. The laser scanner 9 emits a laser beam that blinks in response to an image signal generated by a controller (not shown), and scans the photosensitive drum 2, which is being rotated, with the laser beam. This forms an electrostatic latent image on the photosensitive drum 2. Next, the developer 3 develops the toner stored in the toner container 5 onto the electrostatic latent image, forming a toner image. Meanwhile, the paper 12a or paper 12b placed on the paper feed cassette 10 or multi-tray 11 is fed by the pickup roller 13a or pickup roller 13b. The fed paper is separated into one sheet by the separation roller 14a or separation roller 14b and conveyed toward the register unit 16. Here, the mechanism by which the paper 12a or paper 12b is separated into one sheet utilizes the difference in the friction coefficient between the separation roller 14a and the separation pad 15a, or between the separation roller 14b and the separation pad 15b, and the paper.

[0014] The paper 12c that has reached the registration unit 16 has its leading edge aligned by the registration unit 16, and is then conveyed onto the conveyor belt 6 in time with the formation of the toner image described above. The paper placed on the conveyor belt 6 has the toner images of the respective colors transferred onto it in a sequentially superimposed manner at the nip portions between the photosensitive drums 2Y, 2M, 2C, and 2K of the respective colors and the transfer rollers 7Y, 7M, 7C, and 7K. The paper onto which the toner images have been transferred then passes through a fixing device 8, whereby the unfixed toner is fixed. The paper that has been subjected to the fixing process is conveyed to a discharge port 19 by a plurality of pairs of discharge rollers 18, and is then discharged outside the image forming apparatus 100 and stacked on a discharge stacking section 20.

[0015] [Paper dust collection unit] 2 shows the paper powder collection unit 17, with FIG. 2(a) being a perspective view and FIG. 2(b) being a cross-sectional view. The paper powder collection unit 17 has a paper powder collection roller 201, a sponge member 202, a sponge holding member 203, a first spring member 204, a paper powder collection case 205, and a pair of backflow prevention sheets 206a, 206b. The paper powder collection roller 201 has a surface 201a and a rotating shaft 201b. The paper powder collection roller 201 can rotate in both the clockwise and counterclockwise directions in FIG. 2 around the rotating shaft 201b. The paper powder collection roller 201 will be described below as rotating in response to the conveyance of paper, but it may also be rotated by being driven by a driving source such as a motor that can rotate forward and backward.

[0016] The sponge holding member 203 fixes the sponge member 202. The first spring member 204 biases the sponge member 202 fixed to the sponge holding member 203 towards the paper powder collecting roller 201. The paper powder collecting case 205 rotatably supports the paper powder collecting roller 201. The paper powder collecting case 205 has a hollow shape, and can store the paper powder collected by the paper powder collecting roller 201 in the internal space 205a. The paper powder stored in the internal space 205a of the paper powder collecting roller 201 may be collected manually or automatically.

[0017] In addition, an inner wall 205b of the internal space 205a also has a guide portion 205c for when the sponge holding member 203 is urged against the paper powder collecting roller 201. A pair of backflow prevention sheets 206a, 206b are fixed to the paper powder collecting case 205 so as to be disposed on both sides of the paper powder collecting roller 201.

[0018] Furthermore, a first guide surface 207a and a second guide surface 207b are provided on the outer wall of the paper dust collection case 205, and a second biasing spring member 208, which is a biasing means, is disposed thereon. Hereinafter, they are simply referred to as guide surfaces 207a and 207b. The guide surface 207a is provided upstream of the paper dust collection roller 201 in the conveying direction and faces a guide member 312a, which will be described later. The guide surface 207b is provided upstream of the paper dust collection roller 201 in the conveying direction and faces a guide member 312b, which will be described later. The guide surface 207a is provided to guide the paper 12a fed by the paper feed cassette 10. That is, the leading edge of the paper fed from the paper feed cassette 10 first comes into contact with the guide surface 207a, and is guided along the guide surface 207a to the paper dust collection roller 201, which is located downstream in the conveying direction. The guide surface 207b is provided to guide the paper 12b fed by the multi-tray 11. That is, the leading edge of the paper fed from the multi-tray 11 first comes into contact with the guide surface 207b, and the paper is guided along the guide surface 207b to the paper dust collecting roller 201 located downstream in the conveying direction.

[0019] In this way, the paper powder collection unit 17 is shared by the paper 12a fed from the paper feed cassette 10 and the paper 12b fed from the multi-tray 11. The second biasing spring member 208 biases the paper powder collection unit 17 in the direction of the junction described in Fig. 3. The second biasing spring members 208 are provided on both sides of the paper powder collection roller 201 in the direction of the rotation shaft 201b. Note that the other (rear side) of the two second biasing spring members 208 is not shown in Fig. 2(a).

[0020] [Paper feeding operation] FIG. 3 is an enlarged view of the vicinity of the paper dust collection unit 17 in FIG. 1, and the paper feeding operation will be described in detail with reference to FIG. 3. When feeding paper from the paper feed cassette 10, the pickup roller 13a arranged near one end of the paper feed cassette 10 in the paper feed direction rotates to feed the topmost paper 12a placed on the paper feed cassette 10. At this time, if multiple sheets of paper are fed overlappingly, only the topmost paper is separated at the separation nip portion 310a formed by the separation roller 14a and the separation pad 15a and conveyed further. Specifically, the surfaces of the separation roller 14a and the separation pad 15a are made of a material with a high friction coefficient and low hardness, such as rubber, and generate a high friction force between the fed paper 12a. The friction force between the separation roller 14a and the separation pad 15a and the paper 12a is higher than the friction force between the overlapping sheets of paper conveyed. As a result, the overlapping sheets of paper slip between each other and only the topmost sheet is transported downstream in the transport direction. In Fig. 3, the paths along which the sheets of paper fed from the paper feed cassette 10 and the sheets of paper fed from the multi-tray 11 are transported are shown by dashed lines.

[0021] A first guide member 312a and a second guide member 312b are provided beside the paper dust collecting roller 201 to guide the paper fed from the paper feed cassette 10 and the paper fed from the multi-tray 11 toward the junction 311. Hereinafter, they are simply referred to as the guide members 312a and 312b. Hereinafter, on the upstream side of the junction 311 in the conveying direction, the paper fed from the paper feed cassette 10 and the paper fed from the multi-tray 11 are conveyed along different paths. On the other hand, on the downstream side of the junction 311 in the conveying direction, the paper fed from the paper feed cassette 10 and the paper fed from the multi-tray 11 are conveyed along the same path. For this reason, the boundary between the point where the paper fed from the paper feed cassette 10 and the paper fed from the multi-tray 11 are conveyed along different paths and the point where the paper fed from the paper feed cassette 10 and the paper fed from the multi-tray 11 are conveyed along the same path is represented as the junction 311. The junction 311 is a portion where a first path along which the sheet 12a is transported until it reaches the image forming unit and a second path along which the sheet 12b is transported until it reaches the image forming unit intersect.

[0022] In addition, the side of the paper powder collection roller 201, for a sheet fed from the paper feed cassette 10, is included in the portion along the path that guides the sheet from separation roller 14a through the paper powder collection roller 201 to the register unit 16. In addition, for a sheet fed from the multi-tray 11, the side of the paper powder collection roller 201 is included in the portion along the path that guides the sheet from separation roller 14b through the paper powder collection roller 201 to the register unit 16.

[0023] The paper that has passed through separation nip portion 310a reaches nip portion 315a between paper powder collection roller 201 and guide member 312a while being guided by guide surface 207a and guide member 312a provided on paper powder collection case 205. In other words, a transport path for paper fed from paper feed cassette 10 is formed by guide surface 207a and guide member 312a of paper powder collection unit 17.

[0024] On the other hand, when feeding paper from the multi-tray 11, just the topmost sheet is fed by the pickup roller 13b, separation roller 14b, and separation pad 15b, just like when feeding paper from the paper feed cassette 10. The fed paper is guided by guide surface 207b and guide member 312b provided on the paper powder collection case 205, and reaches nip portion 315b between the paper powder collection roller 201 and guide member 312b. In other words, a transport path for the paper fed from the multi-tray 11 is formed by the guide surface 207b and guide member 312b of the paper powder collection unit 17.

[0025] As described above, the transport paths of the sheets fed from the sheet feed cassette 10 and the multi-tray 11 pass through the nip portion 315a or 315b, and then merge at the junction portion 311 before the register unit 16, and reach the register unit 16. Here, the guide members 312a and 312b are arranged so that the distance between them narrows toward the junction portion 311, and the paper powder collection roller 201 is arranged between the guide members 312a and 312b. As described above, the second biasing spring member 208 (not shown in FIG. 3) biases the paper powder collection unit 17 in the direction of the arrow 313 toward the junction portion 311. In FIG. 3, the biasing force in the direction of the arrow 313 is divided into a direction perpendicular to the imaginary tangent at the nip portion 315a and a direction perpendicular to the imaginary tangent at the nip portion 315b, and these are called component forces 314a and 314b. Force components 314a and 314b of the biasing force of second biasing spring member 208 press paper powder collecting roller 201 toward both guide members 312a and 312b. Force component 314a presses paper powder collecting roller 201 against guide member 312a at nip portion 315a, so that paper powder adhering to a sheet of paper passing through nip portion 315a can be efficiently collected by paper powder collecting roller 201. Force component 314b presses paper powder collecting roller 201 against guide member 312b at nip portion 315b, so that paper powder adhering to a sheet of paper passing through nip portion 315b can be efficiently collected by paper powder collecting roller 201.

[0026] [Paper dust collection operation] Next, the paper dust collection operation of the paper dust collection unit 17 will be described in detail. Here, paper dust refers to a powdery substance that is generated from paper that is fed or transported, and includes fibrous fragments that make up the paper, as well as fillers such as calcium carbonate and talc. When this paper dust is mixed with toner and developed, it can cause image defects by appearing as black dots on the image, or when it accumulates in a cleaner section (not shown), it can cause cleaning defects.

[0027] Also, paper dust may be generated in the process of transporting paper inside the image forming apparatus 100, and a large amount of paper dust is generated from the portions of the paper that come into contact with the separation pads 15a, 15b during paper feeding. This is because the friction coefficient of the surfaces of the separation pads 15a, 15b is high, and because the separation rollers 14a, 14b press the paper against a stationary surface, rubbing and scraping the surface of the paper as it passes through. For this reason, the paper dust collection unit 17 needs to be configured to be able to collect paper dust from the portions of the paper that come into contact with the separation pads 15a, 15b.

[0028] Hereinafter, the surface of the paper that comes into contact with the separation pads 15a, 15b of the paper fed from both the paper feed cassette 10 and the multi-tray 11 will be referred to as the separation surface side. In order to collect paper dust adhering to the separation surface side of the paper, the paper dust collection unit 17 of the first embodiment is configured to bring a paper dust collection roller 201 into contact with the separation surface side of the paper fed from both the paper feed cassette 10 and the multi-tray 11 to collect the paper dust.

[0029] Moreover, the paper powder collection unit 17 of the first embodiment employs a method of charging the surface 201a of the paper powder collection roller 201 and adsorbing paper powder by electrostatic force. Specifically, at least the surface 201a of the paper powder collection roller 201 that comes into contact with paper is made of fluororesin such as PFA (perfluoroalkoxyalkane) that is easily charged. The paper powder collection unit 17 has a sponge member 202 that is a charging member that contacts the paper powder collection roller 201 and charges the paper powder collection roller 201 by friction when the paper powder collection roller 201 rotates. The paper powder collection roller 201 is charged by the sponge member 202 and adsorbs paper powder by electrostatic force. In this way, the surface 201a is pressed by the sponge member 202 made of urethane or nylon, and the paper powder collection roller 201 is rotated to charge the surface and adsorb paper powder. The sponge member 202 also has a function of peeling off paper powder adsorbed on the surface 201a of the paper powder collection roller 201. The details will be explained using Figures 4 and 5.

[0030] [Paper dust collection] (When paper is fed from the paper cassette) When paper is fed from the paper feed cassette 10, the topmost paper 401 of the paper 12a placed on the paper feed cassette 10 passes through the separation nip 310a between the separation roller 14a and the separation pad 15a, as shown in FIG. 4. This generates paper dust, and the paper 401 is conveyed with the paper dust adhering to the surface of the separation surface 401a. Hereinafter, the paper dust adhering to the separation surface 401a of the paper 401 is referred to as paper dust 402 (first paper dust). When the paper 401 reaches the nip 315a between the paper dust collection roller 201 and the guide member 312a in this state, the paper dust 402 is electrostatically adsorbed to the surface 201a of the charged paper dust collection roller 201, and is separated (removed) from the separation surface 401a of the paper 401. Hereinafter, the paper dust adsorbed to the paper dust collection roller 201 is referred to as adsorbed paper dust 405.

[0031] The paper powder collection roller 201 rotates in the direction of the arrow 404, which is a first direction, in accordance with the passage of the paper sheet 401, and the absorbed paper powder 405 is absorbed onto the surface 201a of the paper powder collection roller 201 and is transported as the paper powder collection roller 201 rotates. The absorbed paper powder 405 passes through the backflow prevention sheet 206b and reaches the sponge member 202. The backflow prevention sheet 206b will be described later. The sponge member 202 then scrapes the absorbed paper powder 405 that has been transported from the surface 201a of the paper powder collection roller 201, and causes it to accumulate beside the sponge member 202 as shown at 406 (hereinafter referred to as collected paper powder 406).

[0032] (When paper is fed from the multi-tray) Next, when a sheet is fed from the multi-tray 11, the topmost sheet 501 of the sheets 12b placed on the multi-tray 11 passes through the separation nip 310b between the separation roller 14b and the separation pad 15b, as shown in FIG. 5. This generates paper dust, and the sheet 501 is conveyed with the paper dust adhering to the surface of the separation surface 501a. Hereinafter, the paper dust adhering to the separation surface 501a of the sheet 501 is referred to as paper dust 502 (second paper dust). In this state, when the sheet 501 reaches the nip 315b between the paper dust collection roller 201 and the guide member 312b, the paper dust 502 is electrostatically adsorbed to the surface 201a of the charged paper dust collection roller 201, and is separated (removed) from the separation surface 501a of the sheet 501. Hereinafter, the paper dust adsorbed to the paper dust collection roller 201 is referred to as adsorbed paper dust 505.

[0033] As paper 501 passes, paper powder collection roller 201 rotates in the direction of arrow 504, which is a second direction opposite to the direction in which paper 401 is fed from paper feed cassette 10. Adsorbed paper powder 505 is adsorbed to surface 201a of paper powder collection roller 201 and is transported as paper powder collection roller 201 rotates. Adsorbed paper powder 505 passes through backflow prevention sheet 206a and reaches sponge member 202. Note that backflow prevention sheet 206a will be described later. Then, sponge member 202 scrapes off the transported absorbed paper powder 505 from surface 201a of paper powder collection roller 201, and causes it to accumulate beside sponge member 202 as shown at 506 (hereinafter referred to as collected paper powder 506).

[0034] Meanwhile, collected paper powder 406 that has been collected from paper 401 fed from paper feed cassette 10 and has accumulated beside sponge member 202 is separated from sponge member 202 as paper powder collection roller 201 rotates in the reverse direction. The paper powder that has been separated from sponge member 202 is scraped off from paper powder collection roller 201 by backflow prevention sheet 206b as collected paper powder 507. Note that when paper powder collection roller 201 rotates again in the direction of arrow 404 in FIG. 4, collected paper powder 506 that has been accumulated beside sponge member 202 is similarly scraped off from sponge member 202 and scraped off paper powder collection roller 201 by backflow prevention sheet 206a.

[0035] [Backflow prevention sheet] The first sheet, backflow prevention sheet 206a, and the second sheet, backflow prevention sheet 206b, are sheets made of PET (polyethylene terephthalate) or the like, with a thickness of approximately 0.1 mm or less. One end of the backflow prevention sheets 206a and 206b is fixed to the paper powder collection case 205, and the other end is in oblique contact with the surface 201a of the paper powder collection roller 201. The backflow prevention sheets 206a and 206b are flexible.

[0036] The backflow prevention sheet 206a allows paper powder adsorbed on the surface 201a of the paper powder collecting roller 201 to pass through when rotating in the direction of the arrow 504 in Fig. 5 (one direction). The backflow prevention sheet 206a scrapes off paper powder from the surface 201a of the paper powder collecting roller 201 when rotating in the direction of the arrow 404 in Fig. 4 (reverse direction). In this way, the backflow prevention sheet 206a has elasticity and a contact angle with the paper powder collecting roller 201. In other words, the backflow prevention sheet 206a contacts the paper powder collecting roller 201 so as to be in the counter direction when the paper powder collecting roller 201 rotates in the direction of the arrow 404 in Fig. 4.

[0037] 4 in the direction of arrow 404 (one direction), the backflow prevention sheet 206b allows paper powder adsorbed on the surface 201a of the paper powder collection roller 201 to pass through. When the backflow prevention sheet 206b rotates in the direction of arrow 504 (reverse direction) in FIG. 5, it scrapes off paper powder from the surface 201a of the paper powder collection roller 201. In this way, the backflow prevention sheet 206b has elasticity and a contact angle with the paper powder collection roller 201 that is set. In other words, the backflow prevention sheet 206b contacts the paper powder collection roller 201 in a counter direction when the paper powder collection roller 201 rotates in the direction of arrow 504 in FIG.

[0038] Therefore, when paper is fed from the paper feed cassette 10, the backflow prevention sheet 206b allows the paper powder attracted onto the paper powder collection roller 201 to pass through. At this time, the backflow prevention sheet 206a also scrapes off the collected paper powder 506 that was collected by the backflow prevention sheet 206a when paper was fed from the multi-tray 11 and that has moved from the side of the sponge member 202 due to the reverse rotation of the paper powder collection roller 201.

[0039] On the other hand, when a sheet is fed from the multi-tray 11, the backflow prevention sheet 206a passes the paper dust adsorbed on the paper dust collection roller 201. At this time, the backflow prevention sheet 206b collects the collected paper dust 406 when the sheet is fed from the paper feed cassette 10, and the collected paper dust 406 is moved from the side of the sponge member 202 by the reverse rotation of the paper dust collection roller 201. In this way, the backflow prevention sheets 206a and 206b prevent the paper dust collected in the internal space 205a of the paper dust collection case 205 from flowing back due to the rotation of the paper dust collection roller 201 and leaking to the outside. When a large number of sheets are further fed and conveyed and the above-mentioned collection operation is repeated, the amount of collected paper dust 406, 506, 507 increases, and the paper dust falls by its own weight and is stored at the bottom of the internal space 205a of the paper dust collection case 205 as shown by 407 in FIG. 4 and FIG. 5.

[0040] As described above, one end of backflow prevention sheet 206a is provided downstream of guide surface 207a in the conveying direction, and the other end is in contact with paper powder collection roller 201 in a counter direction to the direction of arrow 404. One end of backflow prevention sheet 206b is provided downstream of guide surface 207b in the conveying direction, and the other end is in contact with paper powder collection roller 201 in a counter direction to the direction of arrow 504. When paper powder collection roller 201 rotates in the direction of arrow 404, backflow prevention sheet 206a does not allow collected paper powder 506 collected by paper powder collection roller 201 to pass downstream of the contact portion with paper powder collection roller 201 in the direction of arrow 404. When paper powder collection roller 201 rotates in the direction of arrow 504, backflow prevention sheet 206a allows absorbed paper powder 505 collected by paper powder collection roller 201 to pass downstream of the contact portion with paper powder collection roller 201 in the direction of arrow 504. When paper powder collecting roller 201 rotates in the direction of arrow 504, backflow prevention sheet 206b does not allow collected paper powder 507 collected by paper powder collecting roller 201 to pass downstream of the contact portion with paper powder collecting roller 201 in the direction of arrow 504. When paper powder collecting roller 201 rotates in the direction of arrow 404, backflow prevention sheet 206b allows absorbed paper powder 405 collected by paper powder collecting roller 201 to pass downstream of the contact portion with paper powder collecting roller 201 in the direction of arrow 404.

[0041] As described above, according to the first embodiment, one paper dust collection roller 201 can remove paper dust generated by rubbing against the separation pads 15a, 15b from sheets fed from both the paper feed cassette 10 and the multi-tray 11. This eliminates the need to provide separate paper dust collection mechanisms for each of the multiple paper feed units as in the conventional technology, and can save space and reduce the number of expensive PFA paper dust collection rollers. This makes it possible to realize a small, low-cost image forming apparatus.

[0042] Here, separation pads 15a, 15b do not need to be provided over the entire width of the paper, and may be placed only in the center of the paper width. And paper dust collection roller 201 does not need to be provided over the entire width of the paper, and may be made wider than or equal to the width of separation pads 15a, 15b. In other words, because paper dust is generated by friction with separation pads 15a, 15b, the width of paper dust collection roller 201 should be set so as to include the area where paper dust is generated. This is the same for other embodiments described later. Note that the width refers to the length in the direction perpendicular to the paper transport direction, or the length in the direction of rotation axis 201b of paper dust collection roller 201.

[0043] As described above, the paper dust collection unit 17 of the first embodiment is provided downstream of the paper feed cassette 10 and the multi-tray 11 in the paper transport direction and upstream of the junction 311. When the paper 401 is fed, the paper dust collection roller 201 comes into contact with the paper 401 and collects the paper dust 402 while rotating in the direction of the arrow 404. When the paper 501 is fed, the paper dust collection roller 201 comes into contact with the paper 501 and collects the paper dust 502 while rotating in the direction of the arrow 504. The guide member 312a faces the paper dust collection roller 201 and forms a part of the first path together with the paper dust collection roller 201, and the guide member 312b faces the paper dust collection roller 201 and forms a part of the second path together with the paper dust collection roller 201. Furthermore, the width of the paper dust collection roller 201, which is the length in the direction perpendicular to the transport direction, is equal to or larger than the width of the separation pads 15a and 15b.

[0044] Furthermore, the paper powder collection roller 201 may be a driven type that does not have a drive source and rotates with the passage of paper, but may be a type that is rotated by a drive source as described above. By driving the paper powder collection roller 201 to rotate with a drive source, it is possible to prevent the paper powder collection roller 201 from rotating idly, and more efficient paper powder collection can be performed.

[0045] Furthermore, the paper powder collection roller 201 is cylindrical, i.e., in the form of a roller, but may be in the form of a rotating brush (brush shape) made of PFA or the like. The rotating brush may be, for example, a cylindrical member with bristles implanted on its surface, which is made rotatable. This also applies to the other embodiments. In addition, although the first embodiment shows an example of the color image forming apparatus 100, the present configuration may be applied to a monochrome image forming apparatus that prints only one color. This also applies to the other embodiments.

[0046] [Other application examples] (Paper dust collection at cash register units) If higher quality is required, the register unit 16, which is a conveying means, may also be provided with a paper dust collection mechanism. The register unit 16 is provided downstream of the junction 311 in the paper conveying direction and upstream of the image forming unit. The register unit 16 clamps the paper and conveys it to the image forming unit. An example of this is shown in FIG. 6(a). In FIG. 6(a), the register roller 16a, which is the second rotating body, is composed of a metal shaft 601 and a rubber roller 602 fixed to the outer periphery thereof and rotating integrally therewith. Meanwhile, the register facing roller 16b, which is the first rotating body, is composed of a metal shaft 603 and a paper dust collection layer 604 fixed to the outer periphery thereof and rotating integrally therewith. Here, the paper dust collection layer 604 of the register facing roller 16b may be a tube made of fluororesin such as PFA, which is easily charged, like the paper dust collection roller 201. The registration unit 16 has a sponge member 605 which is a charging member that contacts the registration facing roller 16b and charges the paper powder collection layer 604 by friction when the registration facing roller 16b rotates. In this manner, the sponge member 605 made of urethane or nylon is in contact with the registration facing roller 16b. The registration facing roller 16b is charged by the sponge member 605 and attracts and collects paper powder by electrostatic force.

[0047] The registration roller 16a is driven to rotate in the direction of an arrow 607 in order to transport the paper 606 that has passed through the junction 311. The registration opposing roller 16b is driven to rotate in the direction of an arrow 608 in order to transport the paper 606 that has passed through the junction 311. Due to the rotation of the registration opposing roller 16b, the paper powder collecting layer 604 is charged by friction with the sponge member 605, and paper powder is attracted to the paper powder, and the paper powder attracted to the paper powder collecting layer 604 is scraped off. The paper powder collected on the paper powder collecting layer 604 is stored inside a second paper powder collecting case 609.

[0048] Here, the registration facing roller 16b is arranged so as to contact the side of the paper 606 that contacts the photosensitive drum 2, that is, the printing surface side 606a, and is preferably made to have a width greater than the maximum paper width (the width of the largest recording material) of the paper that can be transported by the image forming apparatus 100. This allows paper dust to be collected over the entire width of the printing surface side 606a of the paper 606. This prevents paper dust that is generated when cutting the paper and that has previously adhered to the paper from adhering to the photosensitive drum 2 and causing image defects. This also applies to other embodiments described later. Note that the registration facing roller 16b rotates in the direction of the arrow 608 and does not rotate in the reverse direction, so that it does not have backflow prevention sheets 206a and 206b like the paper dust collection unit 17. However, in order to assist or ensure the scraping of paper dust from the paper dust collection layer 604, a scraping sheet may be provided in contact with the paper dust collection layer 604 in a counter direction to the arrow 608 direction of the paper dust collection layer 604.

[0049] (When there are 3 or more paper feeders) In the first embodiment, the image forming apparatus 100 includes two paper feed units, the paper feed cassette 10 and the multi-tray 11, but may include more paper feed units (three or more). For example, as shown in FIG. 6B, the image forming apparatus 100 includes a second paper feed cassette 10a and a third paper feed cassette 10b below the first paper feed cassette 10. Only one sheet of paper is separated from the second paper feed cassette 10a by the separation roller 14c and the separation pad 15c and fed. Only one sheet of paper is separated from the third paper feed cassette 10b by the separation roller 14d and the separation pad 15d and fed.

[0050] The paper dust collection unit 17 can also be applied to the case where the image forming apparatus 100 includes at least one third paper feed section, such as the second paper feed cassette 10a and the third paper feed cassette 10b, on which the third recording material is placed and which is different from the paper feed cassette 10 and the multi-tray 11. In this case, the portions (points in the cross-sectional view) where the third path along which the third recording material is conveyed until it reaches the image forming section intersect with the first path are defined as the second junctions 1401 and 1402, with respect to the junction 311, which is the first junction. In this case, the paper feed cassette 10 may be joined with the conveying path at the junctions 1401 and 1402 before the paper dust collection roller 201, i.e., upstream in the conveying direction of the paper. In other words, the junctions 1401 and 1402 may be upstream of the paper dust collection unit 17 in the conveying direction.

[0051] As a result, both the paper fed from the second paper feed cassette 10a and the paper fed from the third paper feed cassette 10b are transported between the guide surface 207a and the guide member 312a of the paper dust collection unit 17. This also applies to the other embodiments described later.

[0052] As described above, according to the first embodiment, it is possible to effectively remove paper dust from a plurality of paper feed units without increasing the size and cost of the image forming apparatus. EXAMPLES

[0053] [Guide member configuration] Example 2 will be described with reference to Fig. 7. In Example 2, an opening 701 is provided in guide member 312a at a position facing paper powder collection roller 201, and a movable guide 703, which is a first part, is disposed therein. Similarly, an opening 702 is provided in guide member 312b at a position facing paper powder collection roller 201, and a movable guide 704, which is a second part, is disposed therein.

[0054] Moreover, movable guide 703 is urged toward paper powder collecting roller 201 by urging spring 705, which is a first urging means. Similarly, movable guide 704 is urged toward paper powder collecting roller 201 by urging spring 706, which is a second urging means. On the other hand, the two (pair of) second urging spring members 208 used in the first embodiment are not used. The other configurations are the same as those in the first embodiment, so a description thereof will be omitted.

[0055] [Guide bias spring] In the first embodiment, the second biasing spring member 208 is used to bias the paper powder collecting roller 201 against both the two guide members 312a and 312b, but in the second embodiment, the movable guides 703 and 704 are biased against the paper powder collecting roller 201. In the first embodiment, the second biasing spring member 208 presses the guide members 312a and 312b with the component force 314a and the component force 314b of the biasing force of the second biasing spring member 208, respectively, so that the second biasing spring member 208 requires a large elastic force. On the other hand, in the second embodiment, the direction of the biasing force of the biasing springs 705 and 706 is the same as the direction in which the biasing force of the biasing springs 705 and 706 presses the movable guides 703 and 704. This allows the elastic forces of the biasing springs 705 and 706 to be efficiently used as the force for biasing the movable guides 703 and 704 against the paper powder collecting roller 201. Therefore, compared to the second biasing spring member 208, a spring with a smaller elastic force can be used for the biasing springs 705 and 706, which allows for lower costs and improved ease of assembly.

[0056] [Variations] (Movable guide contact and separation) Also, the movable guides 703 and 704 may be configured to be able to move away from the paper powder collecting roller 201. FIG. 8 is a diagram showing a state in which the movable guides 703 and 704 are configured to be able to come into contact with and move away from the paper powder collecting roller 201. When conveying a sheet from the paper feed cassette 10, the movable guide 704 may be moved away as shown in FIG. 8(a), and when conveying a sheet from the multi-tray 11, the movable guide 703 may be moved away as shown in FIG. 8(b). In this manner, in the modified example, when the sheet 12a is fed, the movable guide 703 is brought into contact with the paper powder collecting roller 201 and the movable guide 704 is moved away from the paper powder collecting roller 201. When the sheet 12b is fed, the movable guide 704 is brought into contact with the paper powder collecting roller 201 and the movable guide 703 is moved away from the paper powder collecting roller 201.

[0057] The contact / separation mechanism (contact / separation means) of the movable guides 703 and 704 may have, for example, a cam, and may be configured to switch between contact and separation of the movable guides 703 and 704 by rotating the cam in conjunction with the operation of switching the paper feed unit between the paper feed cassette 10 and the multi-tray 11. This allows only the movable guide on the side that conveys the paper to be in constant contact with the paper powder collection roller 201. Therefore, the resistance during rotation of the paper powder collection roller 201 when the movable guide on one side is in contact with the paper powder collection roller 201 can be kept low compared to when both movable guides are in contact with the paper powder collection roller 201. This allows the paper powder collection roller 201 to rotate smoothly with low torque compared to when the two movable guides are in contact with each other.

[0058] As described above, according to the second embodiment, it is possible to effectively remove paper dust from a plurality of paper feed units without increasing the size and cost of the image forming apparatus. EXAMPLES

[0059] [Configuration of opposing rollers] Example 4 will be described with reference to Fig. 9. In Example 4, an opening 901 is provided in a position of guide member 312a facing paper powder collection roller 201, and an opposing roller 903, which is a first roller, is disposed therein. Also, an opening 902 is provided in a position of guide member 312b facing paper powder collection roller 201, and an opposing roller 904, which is a second roller, is disposed therein. These opposing rollers 903 and 904 are rubber rollers fixed to the outer periphery of a resin or metal shaft, and rotate together.

[0060] Counter roller 903 is rotatably supported by roller holding member 905, and a biasing spring 907 serving as a first biasing means presses roller holding member 905 to bias (contact) counter roller 903 against paper powder collecting roller 201. Counter roller 904 is rotatably supported by roller holding member 906, and a biasing spring 908 serving as a second biasing means presses roller holding member 906 to bias counter roller 904 against (contact) paper powder collecting roller 201.

[0061] Like the biasing springs 705 and 706 in the second embodiment, the biasing force of the biasing springs 907 and 908 also faces the same direction as the direction of pressing the paper powder collection roller 201. Therefore, like the second embodiment, a spring with a smaller elastic force can be used for the biasing springs 907 and 908 compared to the second biasing spring member 208, which can reduce costs and improve ease of assembly.

[0062] Further, the opposing rollers 903 and 904 have approximately the same length as the separation pads 15a and 15b, similar to the paper powder collecting roller 201. The other configurations are the same as those in the first embodiment, and therefore will not be described.

[0063] [Modification: Contact and Separation of Opposing Rollers] Also, similarly to the second embodiment, when a sheet fed from the sheet feed cassette 10 is transported, the opposing roller 904 may be separated from the paper powder collection roller 201. Also, when a sheet fed from the multi-tray 11 is transported, the opposing roller 903 may be separated from the paper powder collection roller 201. That is, when the sheet 12a is fed, the opposing roller 903 is brought into contact with the paper powder collection roller 201 and the opposing roller 904 is separated from the paper powder collection roller 201. On the other hand, when the sheet 12b is fed, the opposing roller 904 is brought into contact with the paper powder collection roller 201 and the opposing roller 903 is separated from the paper powder collection roller 201. The configuration and effects of the contact and separation mechanism are similar to those of the second embodiment, and therefore will not be described.

[0064] [Configuration of each roller when driven by a driving source] In the third embodiment, the paper powder collecting roller 201 and the counter rollers 903 and 904 may be configured to rotate by receiving a driving force from a driving source such as a motor. An example of this is shown in FIG. 10(a). In FIG. 10(a), an extension shaft 1001 extends from one end of the paper powder collecting roller 201 to the outside of the maximum width of the paper to be conveyed. A drive gear 1002 is fixed to the tip of the extension shaft 1001, and the paper powder collecting roller 201 and the drive gear 1002 are supported by a member (not shown) so that they rotate together. Drive gears 1003 and 1004 for the counter rollers 903 and 904 mesh with the drive gear 1002. The drive gears 1003 and 1004 for the counter rollers 903 and 904 are connected to the counter rollers 903 and 904 via drive shafts 1005 and 1006. Further, the drive gear 1002 is connected to a drive source such as a motor capable of rotating in both forward and reverse directions via gears (not shown). That is, the image forming apparatus 100 is provided with a drive source that rotates the paper powder collection roller 201 in the directions of the arrows 404 and 504. The drive gears 1002, 1003, and drive shaft 1005 are included in a first transmission means that transmits the drive force of the drive source to the opposed roller 903. The drive gears 1002, 1004, and drive shaft 1006 are included in a second transmission means that transmits the drive force of the drive source to the opposed roller 904.

[0065] Here, the connection portion between the drive shafts 1005, 1006 and the counter rollers 903, 904 is shown in FIG. 10(b). An opposing roller shaft 1101 extends from one end of the opposing rollers 903, 904, and a spherical portion 1102 is provided at the tip of the opposing roller shaft 1101. A pair of shaft portions 1103 protrude from the spherical portion 1102 in a direction perpendicular to the opposing roller shaft 1101. Meanwhile, a fitting portion 1104 is provided at one end of the drive shafts 1005, 1006, and a pair of slots 1105 are provided therein. The spherical portions 1102 of the opposing rollers 903, 904 are inserted into the fitting portions 1104 of the drive shafts 1005, 1006, and the shaft portions 1103 are fitted into the slots 1105. As a result, the driving force from the drive shafts 1005, 1006 is transmitted to the opposing rollers 903, 904.

[0066] A similar configuration is also provided at the connection parts between the drive gears 1003 and 1004 and the drive shafts 1005 and 1006. The action of these two connection parts ensures that the drive force from the drive gear 1002 can be transmitted to the opposing rollers 903 and 904 even if the thickness of the paper being transported changes or if one of the opposing rollers 903 and 904 moves away from the other and thus the distance to the paper powder collection roller 201 changes.

[0067] In addition, although the opposing rollers 903, 904 are provided with the spherical portion 1102 and the shaft portion 1103, and the drive shafts 1005, 1006 are provided with the fitting portion 1104 and the slotted portion 1105, these may be reversed. That is, the opposing rollers 903, 904 may have the fitting portion and the slotted portion, and the drive shafts 1005, 1006 may have the spherical portion and the shaft portion.

[0068] As described above, by using the configuration of the third embodiment, in addition to the effects described in the first embodiment, it is possible to provide the opposing rollers 903 and 904 with a conveying force for conveying the paper. Therefore, the paper dust collection mechanism does not become a resistance during paper conveyance, and the paper can be conveyed smoothly.

[0069] As described above, according to the third embodiment, it is possible to effectively remove paper dust from a plurality of paper feed units without increasing the size and cost of the image forming apparatus. EXAMPLES

[0070] [Paper dust collection unit] The fourth embodiment will be described with reference to Figs. 11 and 12. In Figs. 11 and 12, the paper powder collection unit 17 is shown as viewed from the side. In the fourth embodiment, the guide members 312a and 312b are provided with a hole 1201a, which is a first hole from which the paper powder collection roller 201 protrudes, and a hole 1201b, which is a second hole from which the paper powder collection roller 201 protrudes. An extension shaft 1202, which is a rotation shaft for rotating the paper powder collection roller 201, extends from both ends of the paper powder collection roller 201 in the direction of the rotation axis. The image forming apparatus 100 includes a bearing portion 1203 that is fixed to the apparatus body and receives the extension shaft 1202. The bearing portion 1203 includes a pair of inclined surfaces, i.e., a first inclined surface 1203a and a second inclined surface 1203b, which form a V-shape in cross section perpendicular to the extension shaft 1202.

[0071] The inclined surface portion 1203a and the inclined surface portion 1203b are provided to form a V-shaped cross section as shown in FIG. 11, and when no paper is fed from the paper feed cassette 10 or the multi-tray 11, the extended shaft 1202, which is also the swing shaft, is located at the acute angle of the V-shape. This state in FIG. 11 is also called the neutral state, and this position is also called the neutral position. The neutral state can also be said to be a state in which the extended shaft 1202, which is also the swing shaft, is in contact with both the inclined surface portion 1203a and the inclined surface portion 1203b (both the inclined surface portion 1203a and the inclined surface portion 1203b). The paper powder collection unit 17 of the fourth embodiment has a second biasing spring member 208, which is a biasing means for biasing the paper powder collection roller 201 toward the junction portion 311, as in the first embodiment.

[0072] The extension shaft 1202 is provided so as to be able to swing along the inclined surfaces 1203a and 1203b of the bearing portion 1203 fixed to the image forming apparatus 100. The bearing portion 1203 is provided on a frame member (not shown) of the main body of the image forming apparatus 100, but only a portion of it is illustrated here for the sake of explanation. Also, in Fig. 11, the transport path of the paper fed from the paper feed cassette 10 and the transport path of the paper fed from the multi-tray 11 are indicated by dashed lines.

[0073] [Operation] In the fourth embodiment, when no paper is being transported, the second biasing spring member 208 causes the extension shaft 1202 to contact both the inclined surfaces 1203a and 1203b. At this time, the paper powder collection roller 201 is in a state where a part of the paper powder collection roller 201 is inserted into both the holes 1201a and 1201b as shown in Fig. 11, in other words, the paper powder collection roller 201 is in a state where the paper powder collection roller 201 protrudes from the paper powder collection unit 17 side through the holes 1201a and 1201b to the opposite area. The other configurations are the same as those of the first embodiment, so a description thereof will be omitted.

[0074] (When feeding from the paper cassette) The conveyance of the paper fed from the paper feed cassette 10 will be described. FIG. 12(a) is a diagram showing the operation of the paper dust collection unit 17 when the paper is fed from the paper feed cassette 10. At this time, the paper fed from the paper feed cassette 10 is conveyed along the guide surface 207a of the paper dust collection unit 17. When the paper 401 reaches the paper dust collection roller 201, the stiffness of the paper pushes the paper dust collection roller 201 to the opposite side to the hole 1201a, so that the paper dust collection roller 201 moves away from the hole 1201a. At this time, the extension shaft 1202 moves away from the neutral position in FIG. 11 and moves along the slope portion 1203b to a position where the force of the paper pressing the paper dust collection roller 201 and the biasing force of the second biasing spring member 208 are balanced, and stops at the balanced position. The extension shaft 1202 is biased against the inclined surface 1203b, and the paper dust collecting roller 201 rotates at this position, passing the paper and collecting the paper dust. Note that the paper dust collecting method is the same as in the first embodiment.

[0075] (When feeding from the multi-tray) Next, the feeding of a sheet of paper fed from the multi-tray 11 will be described. FIG. 12(b) is a diagram showing the operation of the paper dust collection unit 17 when the sheet of paper is fed from the multi-tray 11. At this time, the sheet of paper fed from the multi-tray 11 is transported along the guide surface 207b of the paper dust collection unit 17. When the sheet of paper reaches the paper dust collection roller 201, the stiffness of the sheet of paper pushes the paper dust collection roller 201 in the opposite direction to the hole portion 1201b, so that the paper dust collection roller 201 moves away from the hole portion 1201b. At this time, the extension shaft 1202 moves away from the neutral position in FIG. 11 and moves along the slope portion 1203a to a position where the force of the sheet of paper pushing the paper dust collection roller 201 and the biasing force of the second biasing spring member 208 are balanced, and stops at the balanced position. The extension shaft 1202 is biased against the inclined surface portion 1203a, and the paper dust collecting roller 201 rotates in this position, passing the paper and collecting the paper dust.

[0076] As described above, when neither paper 12a nor paper 12b is being fed, extended shaft 1202 abuts against inclined surface 1203a and inclined surface 1203b. When paper 12a is fed, extended shaft 1202 abuts against inclined surface 1203b, and paper powder collection roller 201 rotates in the direction of arrow 404 with paper powder collection roller 201 protruding from hole 1201b. On the other hand, when paper 12b is fed, extended shaft 1202 abuts against inclined surface 1203a, and paper powder collection roller 201 rotates in the direction of arrow 504 with paper powder collection roller 201 protruding from hole 1201a.

[0077] By adopting the configuration of the fourth embodiment, in addition to the effects of the first embodiment, it is not necessary to use a complex mechanism for separating guide members or an opposing roller in order to reduce the resistance during rotation of the paper powder collection roller 201. Therefore, the paper powder collection unit 17 can have a simple and low-cost configuration.

[0078] As described above, according to the fourth embodiment, it is possible to effectively remove paper dust from a plurality of paper feed units without increasing the size and cost of the image forming apparatus.

[0079] The disclosure of this embodiment includes the following configuration. (Configuration 1) a first paper feed section in which a first recording material is placed; a second paper feed section in which a second recording material is placed and which is different from the first paper feed section; an image forming unit for forming an image on the first recording material or the second recording material; An image forming apparatus comprising: a recovery unit that recovers first paper powder adhering to the first recording material and second paper powder adhering to the second recording material, When a portion where a first path along which the first recording material is transported until it reaches the image forming means and a second path along which the second recording material is transported until it reaches the image forming means intersect is defined as a junction, The recovery means is the first sheet feeding unit and the second sheet feeding unit are provided downstream in a recording material conveying direction and upstream of the junction portion, an image forming apparatus comprising: a rotating body that, when the first recording material is fed, comes into contact with the first recording material and rotates in a first direction to collect the first paper powder, and when the second recording material is fed, comes into contact with the second recording material and rotates in a second direction opposite to the first direction to collect the second paper powder; a first guide member that faces the rotating body and forms a part of the first path together with the rotating body; and a second guide member that faces the rotating body and forms a part of the second path together with the rotating body. (Configuration 2) The above-mentioned image forming apparatus, characterized in that the recovery means has a first guide surface that is located upstream of the rotating body in the transport direction and faces the first guide member, and a second guide surface that is located upstream of the rotating body in the transport direction and faces the second guide member. (Configuration 3) the recovery means includes a first sheet having one end provided downstream of the first guide surface in the conveying direction and the other end abutted against the rotating body in a counter direction to the first direction, and a second sheet having one end provided downstream of the second guide surface in the conveying direction and the other end abutted against the rotating body in a counter direction to the second direction, the first sheet does not allow the second paper powder collected on the rotor to pass downstream of a contact portion with the rotor in the first direction when the rotor rotates in the first direction, and allows the second paper powder collected on the rotor to pass downstream of a contact portion with the rotor in the second direction when the rotor rotates in the second direction, The above-mentioned image forming device is characterized in that, when the rotor is rotating in the second direction, the second sheet does not allow the first paper powder collected on the rotor to pass downstream of the contact point with the rotor in the second direction, and, when the rotor is rotating in the first direction, the second sheet allows the first paper powder collected on the rotor to pass downstream of the contact point with the rotor in the first direction. (Configuration 4) the collecting means has a charging member that contacts the rotating body and charges the rotating body by friction when the rotating body rotates, The image forming apparatus according to any one of the above, characterized in that the rotating body is charged by the charging member, and the first paper powder and the second paper powder are attracted to the surface of the rotating body by electrostatic force. (Configuration 5) The image forming apparatus according to any one of the above, wherein the charging member peels off the first paper powder and the second paper powder that are attracted to the surface of the rotating body. (Configuration 6) the first sheet feeding section has a first separation member that separates only one of the first recording materials when a plurality of recording materials are fed in an overlapping state and conveys the separated first recording materials downstream in the conveying direction; the second sheet feeding section has a second separation member that separates only one of the second recording materials when a plurality of recording materials are fed in an overlapping state and conveys the separated second recording materials downstream in the conveying direction; The image forming apparatus according to any one of the above, wherein the width of the rotating body, which is a length in a direction perpendicular to the transport direction, is equal to or larger than the widths of the first separating member and the second separating member. (Configuration 7) the first guide member has a first biasing means and a first portion that is brought into contact with the rotating body by the first biasing means, The image forming apparatus according to any one of the above, wherein the second guide member has a second biasing means and a second portion that is brought into contact with the rotating body by the second biasing means. (Configuration 8) The above-mentioned image forming apparatus is characterized in that it is provided with a contact / separation means for abutting the first portion on the rotating body and separating the second portion from the rotating body when the first recording material is fed, and for abutting the second portion on the rotating body and separating the first portion from the rotating body when the second recording material is fed. (Configuration 9) the first guide member has a first biasing means and a first roller that is brought into contact with the rotating body by the first biasing means, The image forming apparatus according to any one of the above, wherein the second guide member has a second biasing means and a second roller that is brought into contact with the rotating body by the second biasing means. (Configuration 10) The image forming apparatus as described above further comprises a drive source that rotates the rotating body in the first direction and the second direction. (Configuration 11) a first transmission means for transmitting a driving force of the driving source to the first roller; a second transmission means for transmitting a driving force of the driving source to the second roller; The image forming apparatus according to any one of the above, (Configuration 12) The above-mentioned image forming apparatus is characterized in that it is provided with a contact / separation means for contacting the first roller with the rotating body and separating the second roller from the rotating body when the first recording material is fed, and for contacting the second roller with the rotating body and separating the first roller from the rotating body when the second recording material is fed. (Configuration 13) The recovery means has a rotation shaft that rotates the rotor, the first guide member has a first hole portion through which the rotor protrudes, the second guide member has a second hole portion through which the rotor protrudes, a bearing portion fixed to the image forming apparatus and receiving the rotating shaft; the bearing portion has a first inclined surface and a second inclined surface that form a V-shape in a cross section perpendicular to the rotation shaft, The recovery means is When neither the first recording material nor the second recording material is being fed, the rotation shaft abuts against the first inclined surface and the second inclined surface, When the first recording material is fed, the rotation shaft abuts against the second inclined surface, and the rotor rotates in the first direction in a state where the rotor protrudes from the second hole portion, The above-mentioned image forming device is characterized in that when the second recording material is fed, the rotating shaft abuts the first inclined surface, and the rotating body rotates in the second direction with the rotating body protruding from the first hole portion. (Configuration 14) The image forming apparatus according to claim 1, wherein the recovery means includes a biasing means for biasing the rotating body toward the joining portion. (Configuration 15) The image forming apparatus according to the above, wherein the rotating body is in the form of a roller or a brush. (Configuration 16) a third sheet supply unit that is different from the first sheet supply unit and the second sheet supply unit and that is configured to hold a third recording material; When the junction is a first junction, and a portion where a third path along which the third recording material is transported until it reaches the image forming means intersects with the first path is a second junction, The image forming apparatus according to claim 1, wherein the second junction is located upstream of the recovery means in the transport direction. (Configuration 17) a conveying means including a first rotating body that contacts the printing surfaces of the first recording material and the second recording material and a second rotating body that forms a nip portion with the first rotating body, the first recording material and the second recording material being sandwiched between the first rotating body and the second rotating body and conveyed to the image forming means; the conveying means has a charging member that contacts the first rotating body and charges the first rotating body by friction when the first rotating body rotates, the conveying means is provided downstream of the junction in the conveying direction and upstream of the image forming means, The image forming apparatus according to any one of the above, characterized in that the first rotating body is charged by the charging member, and attracts and collects the first paper powder and the second paper powder by electrostatic force. (Configuration 18) a first paper feed section in which a first recording material is placed; a second paper feed section in which a second recording material is placed and which is different from the first paper feed section; an image forming unit for forming an image on the first recording material or the second recording material; a conveying means having a first rotating body that contacts the printing surfaces of the first recording material and the second recording material and a second rotating body that forms a nip portion with the first rotating body, and conveying the first recording material and the second recording material to the image forming means while sandwiching them between the first rotating body and the second rotating body; An image forming apparatus comprising: the conveying means has a charging member that contacts the first rotating body and charges the first rotating body by friction when the first rotating body rotates, When a portion where a first path along which the first recording material is transported until it reaches the image forming means and a second path along which the second recording material is transported until it reaches the image forming means intersect is defined as a junction, the conveying means is provided downstream of the junction in a conveying direction of the recording material and upstream of the image forming means, The image forming apparatus according to claim 1, wherein the first rotating body is charged by the charging member and attracts and collects paper powder by electrostatic force. (Configuration 19) The above-mentioned image forming apparatus, characterized in that the width of the first rotating body, which is the length in a direction perpendicular to the transport direction, is greater than or equal to the width of the largest recording material that can be transported by the image forming device. [Explanation of symbols]

[0080] 10 Paper feed cassette 11 Multi-tray 17 Paper dust collection unit 201 Paper dust collection roller 311 Junction 312 Guide member

Claims

1. A first paper feed section on which the first recording material is placed, A second recording material is placed on a second paper feeding section, which is different from the first paper feeding section. Image forming means including a transfer member that forms a transfer nip on which an image is transferred to the first recording material or the second recording material, An image forming apparatus comprising, The system includes a collection means for collecting the first paper dust adhering to the first recording material and the second paper dust adhering to the second recording material. When the first path through which the first recording material is transported toward the transfer nip and the second path through which the second recording material is transported toward the transfer nip intersect, the point where these two paths intersect is defined as a merging point. The aforementioned recovery means is It is located downstream of the first and second paper feeding sections in the direction of transporting the recording material, and upstream of the confluence section. An image forming apparatus characterized by comprising: a rotating body that, when the first recording material is fed, contacts the first recording material and rotates in a first direction to collect the first paper dust, and when the second recording material is fed, contacts the second recording material and rotates in a second direction opposite to the first direction to collect the second paper dust; a first guide member that faces the rotating body and together with the rotating body forms a part of the first path; and a second guide member that faces the rotating body and together with the rotating body forms a part of the second path.

2. The image forming apparatus according to claim 1, characterized in that the recovery means has a first guide surface provided upstream of the rotating body in the transport direction and facing the first guide member, and a second guide surface provided upstream of the rotating body in the transport direction and facing the second guide member.

3. The recovery means comprises a first sheet, one end of which is provided downstream of the first guide surface in the conveying direction and the other end of which is in a counter-direction with respect to the first direction and is in contact with the rotating body; and a second sheet, one end of which is provided downstream of the second guide surface in the conveying direction and the other end of which is in a counter-direction with respect to the second direction and is in contact with the rotating body. The first sheet prevents the second paper dust collected by the rotating body from passing downstream of the contact portion with the rotating body in the first direction when the rotating body is rotating in the first direction, and when the rotating body is rotating in the second direction, it allows the second paper dust collected by the rotating body to pass downstream of the contact portion with the rotating body in the second direction. The image forming apparatus according to claim 2, characterized in that when the rotating body is rotating in the second direction, the first paper dust collected on the rotating body is not allowed to pass downstream of the contact portion with the rotating body in the second direction, and when the rotating body is rotating in the first direction, the first paper dust collected on the rotating body is allowed to pass downstream of the contact portion with the rotating body in the first direction.

4. The recovery means includes a charging member that contacts the rotating body and charges the rotating body by friction when the rotating body rotates, The image forming apparatus according to claim 1, characterized in that the rotating body is charged by the charging member and causes the first paper powder and the second paper powder to adhere to the surface of the rotating body by electrostatic force.

5. The image forming apparatus according to claim 4, characterized in that the charging member peels off the first paper powder and the second paper powder adsorbed on the surface of the rotating body.

6. The first paper feeding unit has a first separating member that separates only one of the first recording materials when multiple recording materials are fed overlapping and transports it downstream in the transport direction. The second paper feeding unit has a second separating member that separates only one of the second recording materials when multiple recording materials are fed overlapping and transports it downstream in the transport direction. The image forming apparatus according to claim 1, characterized in that the width of the rotating body, which is the length in a direction perpendicular to the conveying direction, is greater than or equal to the width of the first separating member and the second separating member.

7. The first guide member has a first biasing means and a first portion that contacts the rotating body by the first biasing means, The image forming apparatus according to claim 1, characterized in that the second guide member has a second biasing means and a second portion that contacts the rotating body by the second biasing means.

8. The image forming apparatus according to claim 7, further comprising contact-and-separate means for bringing the first portion of the first recording material into contact with the rotating body and separating the second portion from the rotating body when the first recording material is fed, and for bringing the second portion into contact with the rotating body and separating the first portion from the rotating body when the second recording material is fed.

9. The first guide member includes a first biasing means and a first roller that contacts the rotating body by the first biasing means. The image forming apparatus according to claim 1, characterized in that the second guide member comprises a second biasing means and a second roller that contacts the rotating body by the second biasing means.

10. The image forming apparatus according to claim 9, characterized in that it comprises a drive source for rotating the rotating body in a first direction and a second direction.

11. A first transmission means for transmitting the driving force of the drive source to the first roller, A second transmission means for transmitting the driving force of the aforementioned drive source to the second roller, The image forming apparatus according to claim 10, characterized by comprising the above.

12. The image forming apparatus according to any one of claims 9 to 11, characterized in that it is provided with a contact-and-separation means for bringing the first roller into contact with the rotating body and separating the second roller from the rotating body when the first recording material is fed, and for bringing the second roller into contact with the rotating body and separating the first roller from the rotating body when the second recording material is fed.

13. The recovery means has a rotating shaft that rotates the rotating body, The first guide member has a first hole portion from which the rotating body protrudes, The second guide member has a second hole portion from which the rotating body protrudes, Fixed to the image forming apparatus, and comprising a bearing portion that receives the rotation shaft, The bearing portion has a first inclined surface and a second inclined surface whose cross-section perpendicular to the rotation axis forms a V-shape, The aforementioned recovery means is When neither the first recording material nor the second recording material is being fed, the rotating shaft contacts the first and second inclined surfaces. When the first recording material is fed, the rotating shaft contacts the second inclined surface, and the rotating body rotates in the first direction with the rotating body protruding from the second hole. The image forming apparatus according to claim 1, characterized in that when the second recording material is fed, the rotating shaft contacts the first inclined surface, and the rotating body rotates in the second direction with the rotating body protruding from the first hole.

14. The image forming apparatus according to claim 1 or 13, characterized in that the recovery means has a biasing means for biasing the rotating body toward the confluence.

15. The image forming apparatus according to claim 1, characterized in that the rotating body is roller-shaped or brush-shaped.

16. A third recording material is placed on it, and it is equipped with at least one third paper feeding section that is different from the first paper feeding section and the second paper feeding section. When the aforementioned merging section is designated as the first merging section, and the portion where the third path through which the third recording material is transported toward the transfer nip intersects with the first path is designated as the second merging section, The image forming apparatus according to claim 1, characterized in that the second merging section is located upstream of the recovery means in the transport direction.

17. The device comprises a first rotating body that contacts the printed surfaces of the first recording material and the second recording material, and a second rotating body that forms a nip portion with the first rotating body, and a conveying means that holds the first recording material and the second recording material between the first and second rotating bodies and conveys them to the transfer nip. The transport means includes a charging member that contacts the first rotating body and charges the first rotating body by friction when the first rotating body rotates, The conveying means is provided downstream of the confluence in the conveying direction and upstream of the transfer nip. The image forming apparatus according to claim 1, characterized in that the first rotating body is charged by the charging member and attracts and collects the first paper powder and the second paper powder by electrostatic force.

18. A first paper feed section on which the first recording material is placed, A second recording material is placed on a second paper feeding section, which is different from the first paper feeding section. Image forming means including a transfer member that forms a transfer nip on which an image is transferred to the first recording material or the second recording material, A conveying means comprising a first rotating body that contacts the printed surfaces of the first recording material and the second recording material, and a second rotating body that forms a nip portion with the first rotating body, wherein the first recording material and the second recording material are held between the first and second rotating bodies and conveyed toward the transfer nip, An image forming apparatus comprising, The transport means includes a charging member that contacts the first rotating body and charges the first rotating body by friction when the first rotating body rotates, When the first path through which the first recording material is transported toward the transfer nip and the second path through which the second recording material is transported toward the transfer nip intersect, the point where these two paths intersect is defined as a merging point. The transport means is provided downstream of the confluence in the transport direction of the recording material, and upstream of the transfer nip. The first rotating body is charged by the charging member and collects paper dust by electrostatic force, characterized in that the first rotating body is charged by the charging member and collects paper dust by electrostatic force.

19. The image forming apparatus according to claim 17 or 18, characterized in that the width of the first rotating body, which is the length in a direction perpendicular to the transport direction, is greater than or equal to the width of the largest recording material among the recording materials that can be transported by the image forming apparatus.

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