Paper feeding device and image forming apparatus equipped therewith

Abstract

The present invention provides a paper feeding device that can suppress paper feeding failures, reduce the number of parts, and save space. [Solution] The paper feed device 20 includes a paper tray 24 on which paper P is loaded, and a pickup roller 16 positioned to contact the paper P loaded on the paper tray 24 and to pull out the paper P in order to transport it to the paper transport path S. The paper tray 24 is rotatable, and its inclination angle increases as the amount of loaded paper P decreases. The paper tray 24 has a front end portion 24a located at the end on the paper transport path S side that is movable in the vertical direction, and the front end portion 24a is substantially horizontal regardless of the inclination angle.

Description

Technical Field

[0001] The present disclosure relates to a paper feeding device that pulls out paper from a paper feeding cassette in which paper is stored and feeds the paper to a paper conveyance path, and an image forming apparatus including the same.

Background Art

[0002] In a paper feeding device in an image forming apparatus such as a copying machine or a printer, it is common to pull out paper from a paper feeding cassette in which paper is stored and send it to an image forming unit. In the paper feeding cassette, a mounting table on which paper is stacked is installed, and this mounting table is installed so as to be rotatable around the vicinity of the end on the side opposite to the paper feeding side of the paper. Specifically, the mounting table rotates from a substantially horizontal state so that the end position on the paper feeding side moves upward and tilts. Above the mounting table, a pickup roller is arranged, and the pickup roller is in contact with the paper stacked on the top.

[0003] If the amount of paper stacked on the mounting table decreases due to paper feeding, the mounting table rotates so that the degree of inclination of the mounting table increases accordingly. Thereby, even if the paper decreases, the state in which the pickup roller and the top of the paper are in contact can be maintained, and the paper can be pulled out by the pickup roller.

[0004] According to the paper feeding device having the above-described configuration, since the degree of inclination changes as the mounting table rotates, the stacked paper also inclines. As a result, both the contact position between the pickup roller and the top of the paper and the contact position between the paper and the pickup roller change depending on the degree of inclination. That is, as the inclination of the mounting table increases, the pickup roller contacts the paper on the tip side (conveyance path side) of the top of the paper, and the paper contacts the pickup roller on the upper side of the pickup roller. As a result, the conveyance direction (angle) of the paper conveyed by the pickup roller changes, and the paper feeding angle to the paper feeding roller downstream changes, so that the transfer between the rollers becomes unstable and paper feeding failure may occur.

[0005] A paper feeding device that can suppress such problems has been disclosed. For example, the paper feeding cassette (paper feeding device) disclosed in Patent Document 1 has a configuration in which the pressure plate (mounting platform) on which the recording paper (paper) is stacked moves up and down while remaining in a horizontal state. As a result, the transport direction (angle) of the recording paper transported by the paper feeding roller (pickup roller) is constant, which enables stable extraction of the recording paper and has the effect of suppressing paper feeding failures. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2000-62965 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In this configuration, if the pressure plate rotates, the paper feed side of the pressure plate rises, while the end opposite the paper feed side, which is the center of rotation, does not rise. Because of this configuration, the paper feed roller is positioned on the rising side, and the paper feed roller functions as a regulating member for both the recording paper and the pressure plate.

[0008] In contrast, in the paper feed cassette disclosed in Patent Document 1, the pressure plate is pushed up while remaining horizontal without rotating, so the entire pressure plate and recording paper rise. As a result, the paper feed roller alone can only restrict a portion of the recording paper, and cannot restrict the entire sheet. Therefore, a paper retainer is required to restrict the portion that cannot be restricted by the paper feed roller. Consequently, the paper feed cassette disclosed in Patent Document 1 has the problem of increased parts costs due to the increased number of parts. In addition, space is required to install the paper retainer, which limits the number of recording papers that can be stored in the paper feed cassette and makes miniaturization difficult.

[0009] This disclosure has been made in view of the circumstances described above, and its purpose is to provide a paper feeding device and an image forming apparatus equipped therewith that can suppress paper feeding failures, reduce the number of parts, and save space. [Means for solving the problem]

[0010] A paper feeding device according to one aspect of the present disclosure is a paper feeding device comprising: a paper tray on which paper is stacked; and a pickup roller positioned to contact the paper stacked on the paper tray and to pull out the paper in order to transport the paper to a transport path, wherein the paper tray is rotatable and its inclination angle increases as the amount of paper stacked decreases, and the paper tray has a front end located at the end on the transport path side that is movable in the vertical direction, and the front end is substantially horizontal regardless of the inclination angle.

[0011] As a result, even if the amount of paper stacked on the paper tray changes and the tilt angle of the paper tray changes, the contact pattern between the pickup roller and the paper does not change, allowing for stable paper extraction. Therefore, paper feeding failures can be suppressed. Furthermore, since the tilt angle of the paper tray changes in response to changes in the amount of paper stacked on it, there is no need to provide a member to hold the paper down from above, as in a configuration where the paper tray moves vertically while remaining horizontal. This reduces the increase in component costs and allows for space saving.

[0012] Furthermore, in the paper feeding device described above, the paper tray may have a front end, an axial joint, and a tray body connected to the front end by the joint, and the front end and the tray body may be rotatable relative to each other about the joint, thus forming a link mechanism.

[0013] As described above, the front end of the paper tray and the tray body are rotatable relative to each other, allowing the front end to remain horizontal even when the tray body is tilted. This prevents changes in the contact between the pickup roller and the paper, enabling stable paper extraction. This helps to suppress paper feeding malfunctions.

[0014] Furthermore, in the paper feeding device described above, the movement of the front end may be restricted so that it does not move along the paper transport direction, and the front end moves in the vertical direction, while the end of the main body of the stand described above that is opposite to the transport path side may be movable along the paper transport direction.

[0015] This allows for a smooth transition from a state where both the main body and front end of the mounting platform are horizontal to a state where the main body of the mounting platform is tilted and the front end is horizontal, without hindering the paper feeding operation.

[0016] Furthermore, the above-described paper feeding device may also include a fitting portion connected to the front end and a slit portion into which the fitting portion fits, wherein the movement of the fitting portion is restricted by the slit portion, thereby restricting the movement of the front end.

[0017] This allows for a simple configuration that restricts the movement of the front end so that it does not move along the paper transport direction, and so that it moves only vertically. As a result, manufacturing costs can be reduced.

[0018] Furthermore, in the paper feeding device described above, a push-up section may be provided below the front end to support the movement of the front end, and the push-up section may be provided with two guide sections that protrude upward and contact the front end, and the pickup roller may be positioned between these two guide sections.

[0019] As a result, the front end portion can smoothly move in the vertical direction, and the pickup roller 16 can stably pull out the paper.

[0020] Also, in the above-described paper feeding device, it may be provided with a biasing member for the front end portion to move in the vertical direction.

[0021] As a result, the front end portion can smoothly move in the vertical direction.

[0022] Also, in the above-described paper feeding device, it may be provided with a driving device for the front end portion to move in the vertical direction.

[0023] As a result, the front end portion can smoothly move in the vertical direction.

[0024] An image forming apparatus according to an aspect of the present disclosure is characterized by including the above-described paper feeding device.

[0025] As a result, it is possible to suppress the occurrence of paper feeding failure. It is possible to suppress an increase in component costs and also to save space.

Effect of the Invention

[0026] According to the present disclosure, it is possible to provide a document feeding device that can stably feed a document without causing conveyance abnormalities, and an image forming apparatus including the same.

Brief Description of the Drawings

[0027] [Figure 1] It is a front view showing a perspective view of a schematic configuration of an image forming apparatus according to an embodiment of the present disclosure. [Figure 2] It is a perspective view showing a schematic configuration of a paper feeding device according to an embodiment of the present disclosure. [Figure 3] It is an enlarged cross-sectional view taken along the line A-A of FIG. 2. [Figure 4] It is an enlarged perspective view showing a schematic configuration around a slit portion in a paper feeding device according to an embodiment of the present disclosure. [Figure 5] This is a first schematic diagram illustrating the difference in the state of the paper tray due to changes in the amount of paper loaded in the paper feed cassette according to the embodiment of this disclosure. [Figure 6] This is a second schematic diagram illustrating the difference in the state of the paper tray due to changes in the amount of paper loaded in the paper feed cassette according to the embodiment of this disclosure. [Figure 7] This is a third schematic diagram illustrating the difference in the state of the paper tray due to changes in the amount of paper loaded in the paper feed cassette according to the embodiment of this disclosure. [Modes for carrying out the invention]

[0028] Embodiments relating to this disclosure will be described with reference to the drawings.

[0029] An image forming apparatus according to the first embodiment of this disclosure will be described with reference to the drawings. Figure 1 is a perspective front view showing a schematic configuration of the image forming apparatus according to the embodiment of this disclosure.

[0030] In the coordinate system shown in the following diagram, the X-axis direction represents the left-right direction (lateral direction) when viewing the image forming apparatus 100 from the front, with the positive and negative X-axis directions representing the left and right sides, respectively. The Y-axis direction represents the depth direction (front-back direction) perpendicular to the X-axis, which is the left-right direction, with the positive and negative Y-axis directions representing the operator's side (front side) and the rear side, which is opposite the operator's side, respectively. The Z-axis direction represents the up-down direction, i.e., the vertical direction, with the positive and negative Z-axis directions representing the upper and lower sides, respectively. Note that if only the components of the image forming apparatus 100 are shown without the image forming apparatus 100 itself, the coordinates indicate the state in which the components are incorporated into the image forming apparatus 100.

[0031] The image forming apparatus 100 is a multifunction device having copying, scanning, facsimile, and printing functions, and includes an image reading device 102 and an image forming apparatus main body 101.

[0032] The image reading device 102 includes a reading unit 130 and a document feeder 160 [automatic document feeder (ADF)]. The document feeder 160 is located above the reading unit 130 and is supported so as to be openable and closable relative to the reading unit 130.

[0033] The document feeder 160 transports one or more documents G one by one in sequence. The image reader 102 reads one document G at a time from among the one or more documents G transported by the document feeder 160.

[0034] The reading unit 130 includes a document placement table 130a on which the document G is placed, and a scanning optical system 130c, the scanning optical system 130c reading the document G.

[0035] The image reading device 102 is equipped with a document tray 130a and has a document reading function that reads a document G placed on the document tray 130a. When the document feeder 160 in the image forming apparatus 100 is opened, the document tray 130a above the reading unit 130 is opened, and the document G can be placed on the document tray 130a by hand. The reading unit 130 scans the document G placed on the document tray 130a by scanning the scanning optical system 130c.

[0036] The document feeder 160 also includes a document tray 161 on which the document G is placed, and a document output tray 162 for stacking the document G that has been discharged to the outside. The document feeder 160 transports the document G placed on the document tray 161 to the document reading unit 130b in the reading unit 130, reads the transported document G, and generates image data.

[0037] The image forming apparatus main body 101 comprises an image transfer unit 50, an optical scanning unit 1, an intermediate transfer belt unit 70, a secondary transfer unit 11, a fixing unit 12, a paper transport path S, a paper feed unit 20 having a paper feed cassette 18, and a paper discharge unit 140 having a paper discharge tray 141.

[0038] The image forming apparatus 100 handles image data corresponding to color images using black (K), cyan (C), magenta (M), and yellow (Y), or monochrome images using a single color (for example, black).

[0039] The image transfer unit 50 of the image forming apparatus 100 has four image stations Pa, Pb, Pc, and Pd, corresponding to black, cyan, magenta, and yellow. Each of these image stations Pa, Pb, Pc, and Pd is equipped with a developer 2, a photoreceptor drum 3, a drum cleaning device 4, and a charger 5, and these image stations Pa, Pb, Pc, and Pd form four types of toner images. In other words, in the image forming apparatus 100, there are four of each of the developer 2, photoreceptor drum 3, drum cleaning device 4, and charger 5, each corresponding to black, cyan, magenta, and yellow.

[0040] The optical scanning device 1 exposes the surface of the photoreceptor drum 3 to form an electrostatic latent image. The developing device 2 develops the electrostatic latent image on the surface of the photoreceptor drum 3 to form a toner image on the surface of the photoreceptor drum 3. The drum cleaning device 4 removes and recovers residual toner from the surface of the photoreceptor drum 3. The charger 5 uniformly charges the surface of the photoreceptor drum 3 to a predetermined potential. Through the above series of operations, toner images of each color are formed on the surface of each photoreceptor drum 3.

[0041] The intermediate transfer belt device 70 includes intermediate transfer rollers 6, an endless intermediate transfer belt 71, an intermediate transfer drive roller 72, an intermediate transfer driven roller 73, and a cleaning device 9, all arranged for each image station Pa, Pb, Pc, and Pd. The intermediate transfer belt 71 is an endless belt that can move around and is wrapped around the intermediate transfer drive roller 72 and the intermediate transfer driven roller 73. In other words, the intermediate transfer drive roller 72 and the intermediate transfer driven roller 73 tension the intermediate transfer belt 71. Four intermediate transfer rollers 6 are provided inside the intermediate transfer belt 71 to form four different toner images corresponding to each color. The intermediate transfer rollers 6 transfer the toner images of each color formed on the surface of the photoreceptor drum 3 to the intermediate transfer belt 71.

[0042] The image forming apparatus 100 sequentially transfers and superimposes the toner images of each color formed on the surface of each photoreceptor drum 3 to form a color toner image on the surface of the intermediate transfer belt 71 stretched over the intermediate transfer drive roller 72 and the intermediate transfer driven roller 73. The toner image formed on the intermediate transfer belt 71 is transferred to the paper P by the secondary transfer apparatus 11. In addition, some of the toner image formed on the intermediate transfer belt 71 is not transferred to the paper P and remains on the surface of the intermediate transfer belt 71 as waste toner, which is removed and collected by the cleaning apparatus 9.

[0043] The secondary transfer device 11 forms a transfer nip region TN between the secondary transfer roller 11a and the intermediate transfer belt 71, and transports the paper P that has been transported through the paper transport path S by sandwiching it in the transfer nip region TN. As the paper P passes through the transfer nip region TN, the toner image on the surface of the intermediate transfer belt 71 is transferred to the paper P and it is then transported to the fuser device 12.

[0044] The fuser unit 12 is equipped with a fuser roller 31 and a pressure roller 32 that rotate with the paper P in between. The fuser unit 12 heats and pressurizes the paper P, on which the toner image has been transferred, by sandwiching it between the fuser roller 31 and the pressure roller 32, thereby fixing the toner image to the paper P. Although not shown, a heater, which is a heat source, is placed inside the fuser roller 31, and the heat generated by this heater heats the surface of the fuser roller 31 that comes into contact with the paper P on which the toner image has been transferred.

[0045] The paper feed device 20 comprises a paper feed cassette 18, a paper tray 24 installed inside the paper feed cassette 18, a pickup roller 16, a document feed roller 21, and a separation roller 22, and is located on the underside of the optical scanning device 1.

[0046] The paper feed cassette 18 is a cassette for accumulating and storing the paper P used for image formation. The paper tray 24 is installed inside the paper feed cassette 18, and the paper P is stacked on the paper tray 24. As will be described in detail later, the paper tray 24 rotates and tilts so that the right side (negative X-axis direction side), which is the paper transport path S side of the paper tray 24, becomes higher, so that the top of the paper P comes into contact with the pickup roller 16. When the pickup roller 16 comes into contact with the paper P in this way, the pickup roller 16 can pull out the paper P. As the number of sheets of paper P stacked on the paper tray 24 decreases, the paper tray 24 rotates so that the tilt angle of the paper tray 24 increases, thereby maintaining the state in which the pickup roller 16 and the paper P are in contact.

[0047] The pickup roller 16 pulls out the paper P placed on the paper tray 24, and the paper P pulled out by the pickup roller 16 is separated into individual sheets by the document feed roller 21 and the separation roller 22 and transported along the paper transport path S.

[0048] The paper P transported along the paper transport path S passes through the secondary transfer device 11 and the fixing device 12, is transported to the discharge roller 17, and is discharged into the paper discharge tray 141 in the discharge section 140. The paper transport path S is equipped with a transport roller 13, a registration roller 14, and a discharge roller 17. The transport roller 13 facilitates the transport of the paper P. The registration roller 14 temporarily stops the paper P and aligns the leading edge of the paper P. Furthermore, the registration roller 14 transports the temporarily stopped paper P in accordance with the timing of the color toner image on the intermediate transfer belt 71. The color toner image on the intermediate transfer belt 71 is transferred to the paper P in the transfer nip region TN between the intermediate transfer belt 71 and the secondary transfer roller 11a.

[0049] Although Figure 1 shows only one paper feed cassette 18, the system is not limited to this configuration. Multiple paper feed cassettes 18 may be provided, each loaded with a different type of paper P.

[0050] Furthermore, if the image forming apparatus 100 is to perform image formation on the back side of the paper P as well as the front side, it transports the paper P in the reverse direction from the discharge roller 17 to the paper reversal path Sr. The image forming apparatus 100 reverses the front and back sides of the paper P that has been transported in the reverse direction and guides it back to the registration roller 14. The image forming apparatus 100 then forms an image on the back side of the paper P guided to the registration roller 14 in the same way as the front side, and transports it to the paper discharge tray 141.

[0051] Next, the configuration of the paper feed device 20 will be described in detail with reference to the drawings. Figure 2 is a perspective view showing the schematic configuration of the paper feed device according to the present disclosure. Figure 3 is an enlarged cross-sectional view taken along the line AA in Figure 2. Figure 4 is an enlarged perspective view showing the schematic configuration around the slit portion in the paper feed device according to the present disclosure.

[0052] As shown in Figure 2, a paper tray 24 is located inside the paper feed cassette 18. As described above, the paper tray 24 is rotatable and can change from a horizontal state to an inclined state. In Figure 2, the paper tray 24 is in a horizontal state (parallel to the XY plane), and as the paper tray 24 rotates around a pivot point 23 located near the left end (positive X-axis side) of the paper tray 24 as the pivot point, the right side of the pivot point 23 rises and inclins without the pivot point 23 moving upward. Note that the pivot point 23 of the paper tray 24 cannot move vertically, but it can move horizontally. Therefore, when the paper tray 24 rotates and inclins, the right end (negative X-axis side) of the paper tray 24 does not move horizontally, so as the inclination angle increases, the pivot point 23 moves to the right. This allows the rotation of the paper tray 24 to be smooth.

[0053] The paper mounting platform 24 has a front end portion 24a positioned on the right side, i.e., on the paper transport path S side, and a mounting platform body portion 24b positioned on the left side, and these are rotatably connected to each other by a joint portion 24c which acts as a rotation axis. The joint portion 24c is axial and extends in the front-rear direction (Y-axis direction). In this way, the front end portion 24a and the mounting platform body portion 24b of the paper mounting platform 24 are rotatable to each other around the joint portion 24c and constitute a link mechanism. Details will be described later. The front end portion 24a and the mounting platform body portion 24b rotate to each other, and when the paper mounting platform 24 rotates, the front end portion 24a maintains a horizontal state. That is, the front end portion 24a is parallel to the XY plane. In contrast, as the paper mounting platform 24 rotates, the mounting platform body portion 24b rotates around the pivot point 23, and can be inclined not only to the horizontal plane but also to the horizontal plane. In other words, the mounting base body 24b can also be tilted.

[0054] Here, the configuration for maintaining the front end portion 24a in a horizontal position will be explained with reference to the drawings.

[0055] As shown in Figures 2, 3, and 4, fitting portions 26b protruding along the Y-axis are arranged at both the front side (positive Y-axis direction) and the rear side (negative Y-axis direction) of the front end portion 24a. The paper feed cassette 18 also has slit portions 26a into which the fitting portions 26b protruding from the front and rear ends of the front end portion 24a fit. The slit portion 26a is, for example, a through hole, and the fitting portion 26b fits into the slit portion 26a, thereby limiting the range of motion of the fitting portion 26b. This also limits the range of motion of the front end portion 24a, which is integrated with the fitting portion 26b. Specifically, the slit portion 26a is elongated vertically, and its horizontal length is approximately the same as the horizontal width of the fitting portion 26b. Therefore, the fitting portion 26b fitted into the slit portion 26a can move vertically, but cannot move horizontally, which is the direction in which the paper P is transported in the paper feed device 20. Therefore, the front end portion 24a can move vertically but cannot move horizontally.

[0056] Furthermore, although not shown in Figures 2-4, a push-up portion 28 (see Figures 5-7) is provided below the front end portion 24a to push the front end portion 24a upward. Specifically, a coil spring 27 (see Figures 5-7) is provided below the push-up portion 28 to apply a biasing force to the push-up portion 28. Due to the provision of the coil spring 27 and the push-up portion 28, the front end portion 24a moves vertically while maintaining a horizontal position. As mentioned above, since the fitting portion 26b is fitted into the slit portion 26a, the front end portion 24a does not move horizontally.

[0057] Furthermore, a paper regulating unit 29 is provided inside the paper feed cassette 18. This unit supports the paper P loaded on the paper tray 24 to prevent it from sliding off the tray 24. This prevents the paper P from sliding off the tray 24 even when the tray 24 rotates.

[0058] Next, the relationship between the paper P and the pickup roller 16 due to the rotation of the paper tray 24 will be explained with reference to the drawings. Figure 5 is a first schematic diagram illustrating the difference in the state of the paper tray due to a change in the amount of paper loaded in the paper feed cassette according to the embodiment of this disclosure. Figure 6 is a second schematic diagram illustrating the difference in the state of the paper tray due to a change in the amount of paper loaded in the paper feed cassette according to the embodiment of this disclosure. Figure 7 is a third schematic diagram illustrating the difference in the state of the paper tray due to a change in the amount of paper loaded in the paper feed cassette according to the embodiment of this disclosure.

[0059] As described above, as shown in Figures 5-7, a coil spring 27 is positioned below the front end 24a to push the front end 24a upward. Here, Figure 5 shows the state in which the maximum amount (number) of paper P that can be placed on the paper tray 24 is placed, Figure 6 shows the state in which the amount of paper P has decreased from the state in Figure 5, and Figure 7 shows the state in which the amount of paper P has decreased further from the state in Figure 6. Note that in the state in Figure 5, the paper tray 24 is approximately horizontal. In the states in Figures 6 and 7, the tray body 24b of the paper tray 24 is inclined, and the inclination angle θ1 of the tray body 24b in Figure 6 is smaller than the inclination angle θ2 of the tray body 24b in Figure 7. In other words, the less paper P is placed on the paper tray 24, the larger the inclination angle of the tray body 24b becomes. Note that, as described above, the front end 24a remains horizontal regardless of the amount of paper P placed.

[0060] As described above, a coil spring 27 and a push-up portion 28 are provided. The push-up portion 28 supports the vertical movement of the front end portion 24a, and because these coil springs 27 and push-up portion 28 are provided, the front end portion 24a can move vertically while maintaining a stable horizontal position. In addition, although not shown in Figures 5 to 7, a slit portion 26a and a fitting portion 26b are provided, so as described above, the front end portion 24a moves vertically without moving horizontally.

[0061] Furthermore, guide sections 28a and 28b are installed side by side in the left-right direction on the push-up section 28 so as to protrude upward. Guide sections 28a and 28b are connected to the front end section 24a. In particular, as illustrated in Figures 5 to 7, the position of the pickup roller 16 in the left-right direction is positioned between the guide sections 28a and 28b. This allows the front end section 24a to move stably in the vertical direction while maintaining a horizontal position, and ensures that the contact between the pickup roller 16 and the paper P is in a stable position, resulting in a stable paper pulling operation by the pickup roller 16.

[0062] First, the state shown in Figure 5 is when the maximum amount of paper P is placed on the paper tray 24. In this case, the paper tray 24 (front end portion 24a and tray body portion 24b) is approximately horizontal, and the top of the paper P is in contact with the bottom of the pickup roller 16. As a result, the arrangement of the paper P and the pickup roller 16 is good, and since the paper P is transported horizontally by the pickup roller 16, the transition to the downstream document feed roller 21 and separation roller 22 can be stabilized.

[0063] As the paper load P on the paper tray 24 decreases due to the paper feeding operation from the state shown in Figure 5, the biasing force of the coil spring 27 causes the push-up section 28 to move upward, and as a result, the guide sections 28a and 28b push up the front end 24a, causing it to move upward. Accordingly, the inclination angle of the tray body 24b increases. In this case, the front end 24a remains horizontal and does not move in the left-right direction, so the left end of the tray body 24b, which is the end opposite the paper transport path S, moves to the right, which is the transport direction of the paper P in the paper feeding device 20. As mentioned above, the left end of the tray body 24b is movable in the left-right direction. In other words, it is movable along the transport direction of the paper P in the paper feeding device 20.

[0064] In the state shown in Figure 6, the pickup roller 16 is in contact with the top of the paper P, and since the top of the paper P is approximately horizontal, the top of the paper P is in contact with the bottom of the pickup roller 16 in a relationship similar to that shown in Figure 5. Therefore, even if the amount of paper P loaded on the paper tray 24 decreases, the arrangement between the paper P and the pickup roller 16 remains good, and the paper P can be pulled out stably, just as in the state shown in Figure 5.

[0065] Even if the amount of paper P loaded on the paper tray 24 decreases further due to the paper feeding operation from the state shown in Figure 6, the biasing force of the coil spring 27 will similarly cause the push-up section 28 to move further upward, and as a result the guide sections 28a and 28b will push up the front end 24a, causing it to move upward. Accordingly, the inclination angle of the tray body 24b will increase further. And since the front end 24a will maintain a horizontal position and will not move in the left-right direction, the left end of the tray body 24b will move further to the right.

[0066] In the state shown in Figure 7, the pickup roller 16 is in contact with the top of the paper P, and since the top of the paper P is approximately horizontal, the top of the paper P is in contact with the bottom of the pickup roller 16 in the same relationship as in the states shown in Figures 5 and 6. Therefore, even if the amount of paper P loaded on the paper tray 24 decreases, the arrangement between the paper P and the pickup roller 16 remains good, and the paper P can be pulled out stably, just as in the states shown in Figures 5 and 6.

[0067] Thus, in the paper feed device 20 according to this embodiment, regardless of the amount of paper P stacked on the paper tray 24, the contact arrangement between the top of the paper P and the pickup roller 16 is substantially the same, and the contact pattern between the pickup roller 16 and the paper P does not change. As a result, the paper P is pulled out stably at all times, and paper feeding failures are less likely to occur. More specifically, since the direction in which the paper P is transported by the pickup roller 16 is substantially horizontal and does not change, the transfer to the downstream document feed roller 21 and separation roller 22 can be stabilized.

[0068] Furthermore, since the paper feed device 20 according to this embodiment has a configuration in which the paper mounting table 24 (mounting table body 24b) rotates, there is no need to provide a member to press the paper P from above, as in a configuration in which the paper mounting table 24 moves vertically while remaining horizontal. This reduces the increase in component costs and also allows for space saving.

[0069] Furthermore, since the image forming apparatus 100 according to this embodiment is equipped with a paper feed device 20, paper feeding failures are less likely to occur, the increase in component costs can be suppressed, and space can be saved. (Other embodiments) In the embodiment described above, the front end portion 24a was moved vertically by applying a biasing force to the push-up portion 28 using the coil spring 27. However, the vertical movement of the front end portion 24a may be performed by means other than the coil spring 27. For example, a drive device such as a motor may be provided instead of the coil spring 27, and the vertical movement of the front end portion 24a may be performed by the drive device.

[0070] This disclosure is not limited to the embodiments described above and can be implemented in various other ways. Therefore, such embodiments are merely illustrative in all respects and should not be constrained. The scope of this disclosure is defined by the claims and is not restricted by the text of the specification. Furthermore, any variations or modifications falling within the equivalent scope of the claims are all within the scope of this disclosure. [Explanation of Symbols]

[0071] 1. Optical scanning device 2. Developing device 3. Photoconductor drum 4. Drum cleaning device 5. Charger 6. Intermediate transfer roller 9. Cleaning device 11. Secondary transfer device 11a Secondary transfer roller 12 Fixing device 13 Conveyor rollers 14 Registrola 16 Pickup Roller 17 Discharge roller 18 Paper feed cassette 20 Paper feeder 21 Document feed roller 22 Separation rollers 23 Fulcrum 24 Paper Holder 24a Front end 24b Mounting platform main body 24c joint section 26a Slit section 26b Mating part 27 Coil spring 28 Push-up section 28a, 28b Guide section 29 Paper Regulation Section 31 Fixing roller 32 Pressure rollers 70 Intermediate transfer belt device 71 Intermediate transfer belt 72 Intermediate transfer drive roller 73 Intermediate transfer driven roller 100 Image forming apparatus 101 Image forming apparatus main unit 102 Image reading device 130 Reading Unit 130a Manuscript placement stand 130b Manuscript reading unit 130c scanning optical system 140 Discharge section 141 Paper output tray 160 Document feeder 161 Manuscript Tray 162 Document Output Tray G Manuscript P paper Pa, Pb, Pc, Pd Image Station S Paper transport path Sr Paper Reversal Path TN transfer nip region θ1, θ2 Tilt angle

Claims

1. A paper feeding device comprising: a paper tray on which paper is stacked; and a pickup roller positioned to contact the paper stacked on the paper tray and to pull out the paper in order to transport it to a transport path, The paper tray is rotatable, and the tilt angle increases as the amount of paper stacked decreases. The paper placement platform has a front end located at the end on the transport path side and is movable in the vertical direction. A paper feeding device characterized in that the front end is substantially horizontal regardless of the inclination angle.

2. A paper feeder according to claim 1, The paper resting platform has the front end portion, an axial joint portion, and a resting platform body portion connected to the front end portion by the joint portion. The paper feeding device is characterized in that the front end portion and the base body portion described above are rotatable relative to each other about the joint portion and constitute a link mechanism.

3. A paper feeder according to claim 1, The movement of the front end is restricted so that it does not move along the paper transport direction, and so that it moves in the vertical direction. A paper feeding device characterized in that the end of the mounting base body opposite to the transport path side is movable along the paper transport direction.

4. A paper feeder according to claim 3, The fitting portion connected to the front end, The fitting portion comprises a slit portion into which the fitting portion fits, A paper feeding device characterized in that the movement of the front end is restricted by the movement of the fitting portion being restricted by the slit portion.

5. A paper feeder according to claim 1, It is provided with a push-up portion located below the aforementioned front end that supports the movement of the front end, The aforementioned pushing portion is provided with two guide portions that protrude upward and contact the front end portion. The paper feeding device is characterized in that the pickup roller is located between these two guide sections.

6. A paper feeder according to claim 1, A paper feeding device characterized in that the front end portion is equipped with a biasing member for vertical movement.

7. A paper feeder according to claim 1, A paper feeding device characterized in that the front end portion is equipped with a drive device for moving in the vertical direction.

8. An image forming apparatus characterized by comprising a paper feeding device according to any one of claims 1 to 7.

Images