Paper supply device

Abstract

A paper feeding device is disclosed. The paper feeding device of an embodiment includes a first roller, a second roller, a torque limiter, a support, and a driving section. The first roller contacts a first surface of a sheet and feeds the sheet in a first direction. The second roller is disposed opposite the first roller, and the second roller contacts a second surface of the sheet opposite the first surface by sandwiching the sheet between the second roller and the first roller. The torque limiter imparts a counter torque to the second roller to generate a force in a direction opposite the first direction on the second surface. The support supports the second roller so as to be rotatable. The driving section moves the support and applies a force to the support toward the first roller.

Description

TECHNICAL FIELD

[0001] The present application relates to a paper feeding device. BACKGROUND

[0002] In a paper feeding device, there is a device that sandwiches a sheet between a pair of rollers and feeds the sheet to a first direction. One of the pair of rollers is supported by a torque limiter. Even if two sheets are simultaneously fed between the pair of rollers, only one of the two sheets is fed to a downstream side of the pair of rollers. SUMMARY

[0003] A paper feeding device of an embodiment has a first roller, a second roller, a torque limiter, a support, and a driving section. The first roller contacts a first face of a sheet and feeds the sheet to a first direction. The second roller is disposed in opposition to the first roller, and the second roller sandwiches the sheet between the second roller and the first roller to contact a second face of the sheet, which is a back face of the first face. The torque limiter imparts a counter torque to the second roller to generate a force in a direction opposite to the first direction on the second face. The support supports the second roller so as to be rotatable. The driving section moves the support and applies a force to the support toward the first roller. BRIEF DESCRIPTION OF DRAWINGS

[0004] Figure 1 A schematic configuration diagram of an image forming apparatus of a first embodiment.

[0005] Figure 2 A perspective view of a paper feeding device of the first embodiment.

[0006] Figure 3 A front view of a case where the first and second rollers in the paper feeding device of the first embodiment feed one sheet.

[0007] Figure 4 A front view obtained by superimposing a state where the support in the paper feeding device of the first embodiment is rotated.

[0008] Figure 5 A hardware configuration diagram of the image forming apparatus of the first embodiment.

[0009] Figure 6 A front view of a case where the first and second rollers in the paper feeding device of the first embodiment feed two sheets.

[0010] Figure 7 A graph showing a change in a dynamic pressing point angle with respect to a fulcrum angle in the paper feeding device of the first embodiment.

[0011] Figure 8 A front view of a case where the fulcrum angle in the paper feeding device of a second embodiment is 40°.

[0012] Figure 9 Front view of the case where the fulcrum angle is 35° in the paper feeding device of the second embodiment.

[0013] Figure 10 Front view of the case where the fulcrum angle is 45° in the paper feeding device of the second embodiment.

[0014] Explanation of reference numerals

[0015] 6: control section; 11: humidity sensor; 12: mass sensor; 22, 71: paper feeding device; 25: first roller; 26: second roller; 27: torque limiter; 28: bracket; 29: driving section; 42: moving mechanism; 43: urging member; 45: motor; 46: cam; 47: shaft; 49: driving shaft; 54: first portion; 55: second portion; CA, CB: rotation axis; CC, CE: first rotation axis; CD: second rotation axis; NA: nip; S: sheet; SA: first face; SB: second face; SC: reference face; XA: first direction. DETAILED DESCRIPTION

[0016] A paper feeding device of an embodiment will be described below with reference to the drawings.

[0017] (First Embodiment)

[0018] In the present embodiment, an example in which the paper feeding device is used for a sheet feeding section of an image processing device will be described. The paper feeding device can also be used for a manual feeding tray or the like of the image processing device.

[0019] Figure 1 A schematic configuration diagram of the image processing device of the embodiment. The image processing device of the embodiment is an image forming apparatus 1. The image forming apparatus 1 performs processing of forming an image on a sheet S.

[0020] The image forming apparatus 1 has a housing 10, a scanning section 2, an image forming unit 3, a sheet feeding section 4, a conveyance section 5, a paper discharge tray 7, a flipper unit 9, a control panel 8, and a control section 6.

[0021] The housing 10 forms the outer shape of the image forming apparatus 1. A humidity sensor 11 that detects the humidity of the air outside the image forming apparatus 1 is fixed to the housing 10. The humidity sensor 11 sends the detection result to the control section 6.

[0022] The scanning section 2 reads the light and dark of the image information of a copy target as light and generates an image signal. The scanning section 2 outputs the generated image signal to the image forming unit 3.

[0023] The image forming unit 3 forms an output image by a recording agent such as toner based on an image signal received from the scanning section 2 or an image signal received from the outside. The output image will be referred to as a toner image hereinafter. The image forming unit 3 transfers the toner image onto the surface of the sheet S. The image forming unit 3 heats and presses the toner image on the surface of the sheet S to fix the toner image to the sheet S.

[0024] The sheet supply section 4 supplies the sheets S to the conveying section 5 one by one at a timing at which the image forming unit 3 forms the toner image. The sheet supply section 4 has a sheet housing section 20, a pickup roller 21, and a paper feeding device 22.

[0025] The sheet housing section 20 houses the sheets S of predetermined sizes and kinds.

[0026] The pickup roller 21 takes out the sheets S from the sheet housing section 20 one by one. The paper feeding device 22 supplies the sheets S taken out by the pickup roller 21 to the conveying section 5.

[0027] In the present embodiment, it is theoretically explained that the rotation axis CB of the second roller 26 does not move even if the fulcrum angle Θ changes. As shown in FIG. 2, the first roller 25 is arranged so that the rotation axis CA is along the horizontal plane. The second roller 26 is arranged so that the rotation axis CB is along the horizontal plane. The first roller 25 and the second roller 26 are arranged so that the rotation axis CA and the rotation axis CB are orthogonal to each other. Figure 2 Figure 3 As shown in FIG. 3, the paper feeding device 22 has the first roller 25, the second roller 26, a torque limiter 27, a bracket 28, and a driving section 29.

[0028] For example, the first roller 25 is cylindrical. The first roller 25 is supported by a support member so as to be rotatable about the rotation axis CA of the first roller 25. For example, the first roller 25 is arranged so that the rotation axis CA is along the horizontal plane. The first roller 25 contacts the first surface SA of the sheet S to convey the sheet S to the first direction (downstream side of the conveying direction) XA. A direction opposite to the first direction XA is referred to as the second direction (upstream side of the conveying direction) XB.

[0029] For example, the second roller 26 is cylindrical. The second roller 26 is arranged so as to oppose the first roller 25 below the first roller 25. The second roller 26 is arranged so that the rotation axis CB of the second roller 26 is along the horizontal plane. The second roller 26 sandwiches the sheet S between the second roller 26 and the first roller 25. A nip formed by the first roller 25 and the second roller 26 is referred to as a nip NA.

[0030] The second roller 26 contacts the second surface SB which is the back surface of the first surface SA of the sheet S. The rotation axes CA, CB have lengths in a third direction Y orthogonal to the first direction XA. The third direction Y can also be set as a direction crossing the first direction XA.

[0031] ​For example, a torque limiter 27 is present inside the second roller 26. The torque limiter 27 is coaxial with the second roller 26. In the torque limiter 27, the support shaft 33 protrudes in the third direction Y with respect to the main body 32, respectively. When a torque below a predetermined torque threshold acts between the second roller 26 and the torque limiter 27, the torque limiter 27 is integrated with the second roller 26 and rotates around the rotation axis CB. When a torque exceeding the torque threshold acts between the second roller 26 and the torque limiter 27, the torque limiter 27 supports the second roller 26 so as to be rotatable around the rotation axis CB with an opposite torque corresponding to the torque threshold by sliding with respect to the second roller 26. That is, the torque limiter 27 imparts an opposite torque to the second roller 26 so as to generate a force in the second direction XB on the second face SB of the sheet S.

[0032] The torque exceeding the torque threshold is a torque that tends to rotate the end portion of the first roller 25 side in the second roller 26 in the first direction XA with respect to the torque limiter 27.

[0033] The torque limiter can not be coaxial with the second roller 26 as long as it can cut the torque when an excessive torque acts on the second roller 26.

[0034] The bracket 28 has a main body 36, a pair of first support pieces 37, and a second support piece 38.

[0035] The main body 36 has a length in the third direction Y. The main body 36 is present below the second roller 26. The pair of first support pieces 37 has a length in a manner that each end portion of the main body 36 in the third direction Y faces upward. The support shaft 33 of the torque limiter 27 is fixed to each first support piece 37. The bracket 28 supports the second roller 26 so as to be rotatable.

[0036] The second support piece 38 is fixed to the intermediate portion of the main body 36 in the third direction Y. As shown in FIG. 6, the convex portion 39 is fixed to the lower surface of the second support piece 38. The convex portion 39 is a circular truncated cone shape. Figure 4

[0037] The driving portion 29 rotationally moves the bracket 28. The driving portion 29 applies a force to the bracket 28 toward the first roller 25. As shown in FIG. 7, the driving portion 29 has a moving mechanism 42 and a force applying member 43. The moving mechanism 42 rotationally moves the bracket 28. The moving mechanism 42 moves the bracket 28 by rotating the bracket 28 around the first rotation axis CC. The moving mechanism 42 has a motor 45, a cam 46, and a shaft 47. Figure 2

[0038] As the motor 45, a stepping motor or the like is used. The motor 45 has a main body 48 and a driving shaft 49. The shaft member 52 is supported so as to be rotatable around the first rotation axis CC of the shaft member 52 in the main body 48. There are a plurality of teeth on the outer peripheral surface of the driving shaft 49. ​​

[0039] The cam 46 has a first portion 54 and a second portion 55. The first portion 54 is elliptical. The second portion 55 is a quarter circle. The second portion 55 is a different portion in the cam 46 from the first portion 54. The side of the arc shape in the second portion 55 has a plurality of teeth. The plurality of teeth engages with the plurality of teeth of the drive shaft 49 of the motor 45. The inner corner of about 90° of the top in the second portion 55 is connected to the first end portion of the first portion 54.

[0040] The central portion of the first portion 54 in the long side direction is fixed to the shaft member 52. The first portion 54 of the cam 46 is supported by the motor 45 so as to be rotatable about the first rotation axis CC.

[0041] The shaft 47 has a length in the third direction Y. Here, the central axis of the shaft 47 is referred to as the second rotation axis CD.

[0042] The first end portion of the shaft 47 is fixed to the second portion 55 of the cam 46. The second end portion of the shaft 47 opposite to the first end portion is fixed to the second cam 57. The second cam 57 is supported by the housing 10 so as to be rotatable about the first rotation axis CC. The middle portion of the shaft 47 in the third direction Y is connected to the first support piece 37 of the bracket 28 in a manner rotatable about the second rotation axis CD of the shaft 47. The bracket 28 is rotatably connected to the second rotation axis CD of the shaft 47. The second rotation axis CD is the rotation axis to which the bracket 28 is directly connected. The bracket 28 rotates about the shaft 47. The shaft 47 rotates about the first rotation axis CC together with the cam 46.

[0043] As shown in Figs. 1 and 2, for example, the shaft 47 is disposed in the first direction XA with respect to the rotation axis CB. Figure 2 Figure 3 As shown in Figs. 1 and 2, for example, the shaft 47 is disposed in the first direction XA with respect to the rotation axis CB.

[0044] The first rotation axis CC and the second rotation axis CD of the moving mechanism 42 are rotation axes when the moving mechanism 42 rotationally moves the bracket 28. The moving mechanism 42 has two rotation axes CC, CD.

[0045] As shown in Figs. 1 and 2, for example, the shaft 47 is disposed in the first direction XA with respect to the rotation axis CB. Figure 3

[0046] For example, the urging member 43 is a coil spring.

[0047] The first end portion of the urging member 43 contacts the second support piece 38 of the bracket 28 from below the second support piece 38. The first end portion of the urging member 43 has the protrusion 39. The second end portion of the urging member 43 is disposed on the housing 10.

[0048] The urging member 43 acts on the second support piece 38 of the bracket 28 in the upward direction of the static pressing P. The urging member 43 urges the bracket 28 in the direction of the first roller 25.​​

[0049] The force-applying component can be either a torsion spring or a weight.

[0050] The operation of the paper feeding device 22 configured as described above will be explained here. When viewed along the rotation axis CA of the first roller 25 and the rotation axis CB of the second roller 26, the angle formed by the line connecting the second rotation axis CD and the roll gap NA with the first direction XA on the side closer to the rotation axis CB of the second roller 26 than the first direction XA is called the fulcrum angle θ. The fulcrum angle θ can also be described as the angle formed by the line with the direction from the roll gap NA toward the first direction XA on the side closer to the rotation axis CB than the first direction XA. For example, in Figure 3 and Figure 4 In the state shown by the solid line, the fulcrum angle θ is 39°.

[0051] If a voltage is applied to the motor 45 in a predetermined orientation, the drive shaft 49 rotates relative to the main body 48 in the predetermined orientation. Figure 2 As shown, the cam 46, which engages with the drive shaft 49, rotates toward DA about the first rotation axis CC. The drive shaft 49 of the motor 45 causes the cam 46 to rotate about the first rotation axis CC. For example, the bracket 28 moves to... Figure 4 The position is indicated by a double-dotted line. The fulcrum angle θ is 5°.

[0052] If from Figure 3 and Figure 4 When a voltage is applied to the motor 45 in a direction opposite to the predetermined direction, as shown in solid lines, the drive shaft 49 rotates relative to the main body 48 in a direction opposite to the predetermined direction. Figure 2 As shown, the cam 46, which engages with the drive shaft 49, rotates toward DB about the first rotation axis CC. For example, the bracket 28 moves to... Figure 4 The position is indicated by the dashed line. The fulcrum angle θ is 45°.

[0053] Due to the position of the force-applying component 43 in contact with the protrusion 39, the static pressing P is a basically constant value that does not depend on the fulcrum angle θ.

[0054] In the first embodiment, even if the support 28 rotates about the first rotation axis CC and the fulcrum angle θ changes, the rotation axis CB of the second roller 26 does not move.

[0055] like Figure 1 As shown, the conveying unit 5 conveys the sheet S supplied from the sheet supply unit 4 to the image forming unit 3. The conveying unit 5 has a conveying roller 61 and a blocking roller 62.

[0056] The conveying roller 61 conveys the sheet S supplied from the paper feeding device 22 to the blocking roller 62. The conveying roller 61 brings the leading edge of the sheet S in the conveying direction into contact with the roll gap NB of the blocking roller 62.

[0057] The blocking roller 62 causes the sheet S to be deflected at the nip NB, thereby aligning the position of the leading end of the sheet S in the conveying direction. The blocking roller 62 conveys the sheet S in accordance with the timing at which the image forming unit 3 transfers the toner image to the sheet S.

[0058] The image forming unit 3 will be described.

[0059] The image forming unit 3 has a plurality of image forming portions 65, a laser scanning unit 66, an intermediate transfer belt 67, a transfer portion 68, and a fixing device 69.

[0060] The image forming portion 65 has a photosensitive drum 70. The image forming portion 65 forms a toner image corresponding to an image signal from the scanning portion 2 or an external device on the photosensitive drum 70. The plurality of image forming portions 65 respectively form toner images based on yellow, magenta, cyan, and black toners.

[0061] A charger, a developer, and the like are arranged around the photosensitive drum 70. The charger charges the surface of the photosensitive drum 70. The developer accommodates a developer containing yellow, magenta, cyan, and black toners. The developer develops an electrostatic latent image on the photosensitive drum 70. The toner images based on the various colors of toners are formed on the photosensitive drum 70.

[0062] The laser scanning unit 66 scans a laser beam L to expose the photosensitive drum 70 that is charged. The laser scanning unit 66 exposes the photosensitive drum 70 of the image forming portion 65 of each color using a laser beam LY, LM, LC, LK that is different for each color. The laser scanning unit 66 forms an electrostatic latent image on the photosensitive drum 70.

[0063] The intermediate transfer belt 67 once transfers the toner image on the surface of the photosensitive drum 70.

[0064] The transfer portion 68 transfers the toner image once transferred on the intermediate transfer belt 67 to the surface of the sheet S at a secondary transfer position.

[0065] The fixing device 69 heats and presses the toner image transferred on the sheet S to fix the toner image to the sheet S.

[0066] The reversing unit 9 reverses the sheet S so as to form an image on the back surface of the sheet S. The reversing unit 9 reverses the sheet S discharged from the fixing device 69 by turning around. The reversing unit 9 conveys the reversed sheet S toward the blocking roller 62.

[0067] The sheet S on which the image is formed and which is discharged is placed on the paper discharge tray 7.

[0068] The control panel 8 is a part of an input section in which an operator inputs information for operating the image forming apparatus 1. The control panel 8 has a touch panel, various hard keys.

[0069] The control section 6 performs control of each section of the image forming apparatus 1.

[0070] Figure 5 is a hardware configuration diagram of the image forming apparatus 1 according to the embodiment. The image forming apparatus 1 includes a CPU (Central Processing Unit) 91, a memory 92, an auxiliary storage device 93, and the like connected by a bus, and executes a program. The image forming apparatus 1 functions as an apparatus including the scanning section 2, the image forming unit 3, the sheet supply section 4, the conveyance section 5, the reversing unit 9, the control panel 8, and the communication section 90 by executing the program.

[0071] The CPU 91 functions as the control section 6 by executing the program stored in the memory 92 and the auxiliary storage device 93. The control section 6 controls the operation of each functional section of the image forming apparatus 1. Specifically, the control section 6 controls the driving section 29 on the basis of the detection result of the humidity sensor 11.

[0072] The auxiliary storage device 93 is configured using a hard disk device, a semiconductor storage device, or the like. The auxiliary storage device 93 stores information. The auxiliary storage device 93 stores a predetermined humidity threshold value and the like.

[0073] The communication section 90 is configured to include a communication interface for connecting the image forming apparatus 1 to an external apparatus. The communication section 90 communicates with the external apparatus by means of the communication interface.

[0074] A mechanism for supplying one sheet S to the sheet supply section 4 will be described.

[0075] As shown in Figure 3 , the radius of the outer circumferential surface of the second roller 26 is denoted by r. For example, the unit of the radius r is "cm". The torque threshold value of the torque limiter 27 is denoted by TL. For example, the unit of the torque threshold value TL is "cN m (centiNewtons meter)". For example, the torque threshold value is a value of 2.94 cN m or more and 4.9 cN m or less.

[0076] The return force of the torque limiter 27 in the second direction XB is denoted by F tl . For example, the unit of the return force F tl is "N". For example, the unit of the static pressing P is "N".

[0077] As shown in Figure 3 , a case in which one sheet S is conveyed by the first roller 25 and the second roller 26 will be described.

[0078] The return force F is calculated by (1) formula tl .

[0079] F tl = TL / r · · (1)

[0080] The return force F passing through the torque limiter 27 in the case of conveying one sheet S is calculated by (2) formula tl The rotational force P1 around the second rotation axis CD generated is set. For example, the unit of the rotational force P1 is "N".

[0081] At this time, the rotational force P1 is calculated by (2) formula.

[0082] P1 = F tl × tan θ · · (2)

[0083] The dynamic pressing PF1 in the case of conveying one sheet S is calculated by (3) formula. The dynamic pressing PF1 is the force acting vertically on the sheet S.

[0084] PF1 = F tl × tan θ + P

[0085] = P1 + P · · (3)

[0086] The static friction coefficient between the first roller 25 and the sheet S is set as μ f . The conveying force F of the first roller 25 is calculated by (4) formula f .

[0087] F f = μ f × P · · (4)

[0088] The condition of conveying one sheet S to the first direction XA further than the first roller 25 and the second roller 26 is calculated by (5) formula.

[0089] F f > F tl · · (5)

[0090] In this case, the torque limiter 27 slides. The second roller 26 rotates around the rotation axis CB toward DC with respect to the torque limiter 27. Since the second roller 26 is supported by the torque limiter 27, the bracket 28 rotates around the second rotation axis CD. The second roller 26 is pressed to the sheet S side, and the dynamic pressing PF1 which makes the second roller 26 bite into the first roller 25 is generated. The dynamic pressing PF1 is also the biting force. The sheet S and the second roller 26 rotate together, and one sheet S is conveyed to the first direction XA further than the first roller 25 and the second roller 26.

[0091] For example, in the case of lowering the static friction coefficient μ f , the conveying force F fThe risk of causing poor conveyance of the sheet S arises. In this case, the fulcrum angle θ is increased to increase the dynamic pressing PF1. The (5) formula becomes satisfied, and the risk of causing poor conveyance of the sheet S is eliminated.

[0092] As shown in Fig. 1, a first roller 25 and a second roller 26 are arranged in the first direction XA. The first roller 25 and the second roller 26 are arranged so as to be able to convey a sheet S. The first roller 25 and the second roller 26 are arranged so as to be able to convey two sheets S. The first roller 25 and the second roller 26 are arranged so as to be able to convey one sheet S to a position farther than the first roller 25 and the second roller 26 in the first direction XA. Figure 6 As shown in Fig. 1, a first roller 25 and a second roller 26 are arranged in the first direction XA. The first roller 25 and the second roller 26 are arranged so as to be able to convey a sheet S. The first roller 25 and the second roller 26 are arranged so as to be able to convey two sheets S. The first roller 25 and the second roller 26 are arranged so as to be able to convey one sheet S to a position farther than the first roller 25 and the second roller 26 in the first direction XA.

[0093] The static friction coefficient between the sheets S is set to μ pp . The returning force generated by the static friction coefficient μ pp and the static pressing P is set to F pp . The returning force F pp is found by the (11) formula.

[0094] F pp = μ pp × P··(11)

[0095] The turning force around the second rotation axis CD generated by the static friction coefficient μ pp and the static pressing P in the case of conveying two sheets S is set to P2.

[0096] The turning force P2 is found by the (12) formula.

[0097] P2 = F pp × tan θ··(12)

[0098] The dynamic pressing PF2 in the case of conveying two sheets S is found by the (13) formula. The dynamic pressing PF2 is a force acting perpendicularly to the sheet S.

[0099] PF2 = F pp × tan θ + P

[0100] = P2 + P··(13)

[0101] The condition for conveying one sheet S to a position farther than the first roller 25 and the second roller 26 in the first direction XA is found by the (14) formula and the (15) formula.

[0102] F tl > F pp ··(14)

[0103] F f > -F pp ··(15)

[0104] If the (14) formula is satisfied, the torque limiter 27 does not slip. The second roller 26 rotates relative to the torque limiter 27 toward the direction DC around the rotation axis CB. Even in this case, the dynamic press PF2 in which the second roller 26 bites into the first roller 25 is generated. The end of the first direction XA of the lower sheet S stops at the nip NA. The lower sheet S is separated from the upper sheet S. If the (15) formula is satisfied, the upper sheet S is conveyed to the first direction XA more than the first roller 25 and the second roller 26.

[0105] There is a return force F pp In the case where the stiffness of the sheet S, the static friction coefficient μ pp of the sheet S, the smoothness of the sheet S, and the like, and the environment such as humidity increase. In this case, there is a risk that the (14) formula becomes not satisfied, the torque limiter 27 slips, and the lower sheet S is conveyed to the first direction XA.

[0106] In this case, the fulcrum angle θ is reduced to reduce the dynamic press PF2. The (14) formula becomes satisfied, and the torque limiter 27 becomes not to slip. The risk of causing the lower sheet S not to be conveyed is eliminated.

[0107] The results of measuring the dynamic presses PF1, PF2 by experiments are shown in Figure 7 In Figure 7 , the horizontal axis represents the fulcrum angle θ, and the vertical axis represents the dynamic presses PF1, PF2. The curve L1 represents the dynamic press PF1 in the case of conveying one sheet S. The curve L2 represents the dynamic press PF2 in the case of conveying two sheets S. The curve L2 is the dynamic press PF2 for the upper sheet S. The fulcrum angle θ is changed from 5° to 45°.

[0108] For each of the dynamic presses PF1, PF2, the dynamic presses PF1, PF2 gradually become larger as the fulcrum angle θ becomes larger. For a certain fulcrum angle θ, the dynamic press PF1 is larger than the dynamic press PF2. If the dynamic press PF1 changes, the conveyance force F f that conveys the sheet S to the first direction XA changes. If the dynamic press PF2 changes, the conveyance force F f that conveys the upper sheet S to the first direction XA changes.

[0109] In the image forming apparatus 1, when the detection result of the humidity sensor 11 exceeds the humidity threshold value, the control section 6 rotates and moves the bracket 28 by the driving section 29 to make the fulcrum angle θ smaller.

[0110] As explained above, in the paper feeding device 22 of the present embodiment, since the driving section 29 applies a force to the holder 28 toward the first roller 25, it is possible to firmly sandwich the sheet S between the first roller 25 and the second roller 26. If the driving section 29 rotationally moves the holder 28, the fulcrum angle θ changes, and the dynamic pressure PF2 changes. By appropriately adjusting the dynamic pressure PF2, it is possible to suppress the two sheets S from being fed at once to a position farther than the first roller 25 and the second roller 26 in the first direction XA.

[0111] The driving section 29 has a moving mechanism 42 and a force applying member 43. It is possible to separately perform the movement of the holder 28 and the application of a force to the holder 28 toward the first roller 25 by the moving mechanism 42 and the force applying member 43.

[0112] The moving mechanism 42 rotationally moves the holder 28. Rotation is easier to perform than parallel movement using a rotation shaft of a general motor or the like.

[0113] The first rotation shaft CC at which the moving mechanism 42 rotationally moves the holder 28 is coaxial with the rotation shaft CB of the second roller 26. Even if the holder 28 rotates around the first rotation shaft CC, it is possible to suppress the rotation shaft CB of the second roller 26 from moving to change the position of the nip NA.

[0114] The moving mechanism 42 has a motor 45, a cam 46, and a shaft 47. It is possible to rotationally move the holder 28 by such a simple configuration of the motor 45, the cam 46, and the shaft 47.

[0115] The motor 45 has a drive shaft 49 that rotationally moves the cam 46 around the first rotation shaft CC. In addition to the motor 45 and the cam 46, it is possible to rotationally move the cam 46 around the first rotation shaft CC without using a gear or the like.

[0116] In the image forming apparatus 1 of the present embodiment, it is possible to configure the image forming apparatus 1 using the paper feeding device 22 that suppresses the two sheets S from being fed at once to a position farther than the first roller 25 and the second roller 26 in the first direction XA.

[0117] The image forming apparatus 1 has the humidity sensor 11 and the control section 6. When the detection result of the humidity sensor 11 exceeds the humidity threshold value, the holder 28 is rotationally moved by the driving section 29 to make the fulcrum angle θ smaller. Since the dynamic pressure PF2 becomes smaller if the fulcrum angle θ becomes smaller, it is possible to easily separate the two sheets S in the case of feeding the two sheets S.

[0118] The paper feeding device 22 and the image forming apparatus 1 of the present embodiment can be variously modified as explained below.

[0119] As Figure 3As shown, the first rotation axis CE at the time of the rotational movement of the support 28 by the movement mechanism 42 can also be on the reference plane SC including the rotation axis CA of the first roller 25 and the rotation axis CB of the second roller 26. For example, the first rotation axis CE exists between the rotation axis CA and the rotation axis CB other than the rotation axes CA, CB on the reference plane SC.

[0120] If configured as in this modification example, the position of the nip NA can be changed by suppressing the movement of the rotation axis CB of the second roller 26 within a certain range at the time of the rotation of the support 28 around the first rotation axis CE.

[0121] As shown in Figure 1 The image forming apparatus 101 can also have a quality sensor 12 that detects the quality of the sheet S. In this case, a predetermined quality threshold and the like are stored in the auxiliary storage device 93 of the control section 6. The control section 6 controls the driving section 29 based on the detection result of the quality sensor 12.

[0122] For example, the image forming apparatus 101 of this modification example is used to form an image on a sheet S that is thick and has a relatively large quality. The quality sensor 12 can also be a timer that measures the time required for the sheet S to move in a predetermined conveyance path. Because, generally speaking, the greater the quality of the sheet S, the longer the time required for the sheet S to move in the predetermined conveyance path.

[0123] When the detection result of the quality sensor 12 exceeds the quality threshold, the control section 6 in the image forming apparatus 101 causes the support to rotate and move by the driving section 29 to make the fulcrum angle θ large. Since the dynamic pressing force PF2 becomes large if the fulcrum angle θ is made large, the sheet S can be accurately conveyed to a position further in the first direction XA than the first roller 25 and the second roller 26 even if the quality of the sheet S is relatively large.

[0124] (Second Embodiment)

[0125] In this embodiment, as with the paper feeding apparatus of the actual machine, it is explained that the rotation axis CB of the second roller 26 moves if the fulcrum angle θ changes.

[0126] In Figure 8 In the paper feeding apparatus 71 shown, the first rotation axis is arranged at a position different from the rotation axis CB of the second roller 26 with respect to the paper feeding apparatus 22 of the first embodiment. The change in the position of the first rotation axis is complicated due to the respective configurations of the image forming apparatus.

[0127] In Figure 8 A state in which the fulcrum angle θ is 40° in the paper feeding apparatus 71 is shown. In this state, the nip NA exists on the reference plane SC.

[0128] In Figure 9A state in which the fulcrum angle θ is 35° in the paper feeding device 71 is shown in (A). In this state, the nip NA exists further in the second direction XB than the reference surface SC.

[0129] In Figure 10 A state in which the fulcrum angle θ is 45° in the paper feeding device 71 is shown in (B). In this state, the nip NA exists further in the first direction XA than the reference surface SC.

[0130] It is known that even the paper feeding device 71 configured as such, if the fulcrum angle θ changes, the dynamic pressing changes.

[0131] Even the paper feeding device 71 of the second embodiment can have the same effect as the paper feeding device 22 of the first embodiment.

[0132] In the first, second embodiments and the modified example, the moving mechanism can also be a mechanism that moves the bracket 28 in parallel.

[0133] The image processing device is assumed to be the image forming device 1. The image processing device can also be a device that forms an image on the sheet S by a colorless toner.

[0134] The image processing device is assumed to have the control section 6, but the paper feeding device 71 can also have the control section 6.

[0135] According to at least one embodiment described above, it is possible to suppress the conveyance of two sheets S at a time to further in the first direction XA than the first roller 25 and the second roller 26 by having the driving section 29.

[0136] Although several embodiments have been described, these embodiments are presented by way of example only, and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and equivalents thereof recited in the claims.

Claims

1. A paper feeding device characterized by comprising: Possessing: a first roller that contacts a first surface of a sheet and conveys the sheet in a first direction; a second roller that is disposed in opposition to the first roller and that contacts a second surface of the sheet, which is the back surface of the first surface, by sandwiching the sheet between the second roller and the first roller; a torque limiter that imparts a counter torque to the second roller to generate a force in a direction opposite to the first direction on the second surface; a support that supports the second roller so as to be rotatable; and a drive section that moves the support and applies a force to the support toward the first roller, the drive section has: a movement mechanism that moves the support; and a force applying member that applies a force to the support toward the first roller, the movement mechanism moves the support by rotating the support around a first rotation axis, the first rotation axis is located on a reference surface that includes a rotation axis of the first roller and a rotation axis of the second roller.

2. The paper feeding device according to claim 1, wherein the first rotation axis is coaxial with the rotation axis of the second roller.

3. The paper feeding device according to claim 1, wherein the movement mechanism has: a cam whose first portion is supported so as to be rotatable around the first rotation axis; a shaft that has a length in a second direction that intersects the first direction, and that rotates around the first rotation axis together with the cam; and a motor that rotates the cam around the first rotation axis, the support rotates around the shaft.

4. The paper feeding device according to claim 3, wherein the motor has a drive shaft that is fitted to a side surface of the cam and rotates the cam around the first rotation axis.

5. The paper feeding device according to claim 1, wherein when an angle that is formed by a line that links a second rotation axis and a nip of the first roller and the second roller and the first direction is set as a fulcrum angle, the paper feeding device possesses: a humidity sensor that detects humidity; and a control section that, when a detection result of the humidity sensor exceeds a predetermined humidity threshold value, rotates and moves the support by the drive section so as to make the fulcrum angle smaller, the second rotation axis is connected to the support so as to be rotatable.

6. The paper feeding device according to claim 1, wherein when an angle that is formed by a line that links a second rotation axis and a nip of the first roller and the second roller and the first direction is set as a fulcrum angle, the paper feeding device possesses: a mass sensor that detects a mass of the sheet; and a control section that, when a detection result of the mass sensor exceeds a predetermined mass threshold value, rotates and moves the support by the drive section so as to make the fulcrum angle larger, the second rotation axis is connected to the support so as to be rotatable. ​

Images