Feeding device and image forming apparatus

Abstract

To provide a feeding device by floating sheets, improved in an operation rate of the feeding device, while reducing a work load of a user.SOLUTION: A feeding device determines whether or not a sheet residual amount of a first feeding part is less than a threshold (S804), causes the first feeding part to execute feeding operation for feeding a sheet floated by a blowing part to a suction feeding part (S805), in response to the determination that the sheet residual amount is equal to or more than the threshold (S804: No), and causes a second feeding part to feed the sheet in place of the first feeding part (S811), in response to the determination that the sheet residual amount is less than the threshold (S804: Yes).SELECTED DRAWING: Figure 11

Description

[Technical Field]

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

[0002] Conventionally, a feeding device has been known that includes a sheet stacking section on which multiple sheets are stacked in a stacked state, an air blowing section that blows air from the side of the multiple sheets stacked on the sheet stacking section to lift the top sheet, and an adsorption feeding section that is positioned above the sheet stacking section and adsorbs the sheet that has been lifted by the air blowing section and feeds it in the feeding direction.

[0003] Such a feeding device further includes a lifting mechanism that raises and lowers the sheet stacking unit so that the air from the air blowing unit hits the top sheet stacked on the sheet stacking unit. However, if the sheet stacking unit is raised too high, the sheet stacking unit may block the air from the air blowing unit, which is a problem.

[0004] On the other hand, in a feeding device having multiple paper feed ports, if an abnormality occurs in paper feeding from a first paper feed port, there is a technology that switches to a second paper feed port different from the first paper feed port and continues paper feeding (see, for example, Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned problem may be solved by applying the technology of Patent Document 1 to a feeding device that floats and feeds sheets. However, the technology of Patent Document 1 poses a new problem in that even if there are sufficient sheets remaining in the first paper feed port, it is treated as if there are no sheets, which leads to a notification to the user that there is a need to unnecessarily replenish sheets.

[0006] The present invention has been made to solve such problems, and aims to provide a technology for improving the operating rate of a feeding device that floats and feeds sheets while reducing the workload of the user. [Means for solving the problem]

[0007] In order to solve the above-described problems, one aspect of the present invention provides a sheet feeding device including a first feeding section that floats and feeds sheets, a second feeding section that feeds sheets, and a controller that causes the first feeding section and the second feeding section to feed sheets, wherein the first feeding section includes a sheet stacking section on which a plurality of sheets are stacked in a stacked state, an air blowing section that blows air from the side of the plurality of sheets stacked on the sheet stacking section to float the topmost sheet, a suction feeding section that is disposed above the sheet stacking section and sucks the sheet floated by the air blowing section and feeds it in a feeding direction, and a remaining amount detection sensor that detects the remaining amount of sheets stacked on the sheet stacking section. a feeding detection sensor that detects the sheet fed by the suction feeding unit, the controller determines whether the remaining amount of sheets in the first feeding unit is less than a threshold value, and, in response to determining that the remaining amount of sheets is equal to or greater than the threshold value, causes the first feeding unit to perform a feeding operation of feeding the sheets floated by the air blowing unit to the suction feeding unit; In response to the sheet not being detected by the feeding detection sensor, the second feeding unit is caused to feed the sheet instead of the first feeding unit; in response to determining that the remaining amount of sheets in the first feeding unit is less than the threshold, the first feeding unit is caused to retry the feeding operation up to N times (N is an integer of 2 or more) until the sheet is detected by the feeding detection sensor; and in response to the sheet not being detected by the feeding detection sensor even after the first feeding unit has performed the feeding operation N times, the second feeding unit is caused to feed the sheet instead of the first feeding unit. It is characterized by: [Effects of the Invention]

[0008] According to the present invention, in a feeding device that floats and feeds sheets, it is possible to reduce the workload of a user and improve the availability of the feeding device. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating an internal configuration of an image forming apparatus. [Figure 2] FIG. 2 is a schematic diagram of a first feeding section. [Figure 3] 10A to 10C are diagrams showing the operation of the first feeding section. [Figure 4] FIG. 2 is a diagram showing the hardware configuration of the image forming apparatus. [Figure 5]Functional block diagram of the controller. [Figure 6] 10 is a flowchart of a parameter setting process based on the thickness of a sheet. [Figure 7] 10 is a flowchart of a parameter setting process based on a paper size. [Figure 8] 10 is a flowchart of a feeding process according to the embodiment. [Figure 9] FIG. 4 is a schematic diagram showing the state of the feeding section during a feeding process. [Figure 10] 10 is a flowchart of a feeding process according to the first modification. [Figure 11] 10 is a flowchart of a feeding process according to a second modification. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the internal configuration of an image forming apparatus 100. As shown in Fig. 1, the image forming apparatus 100 mainly includes a first feeding section 110 and a second feeding section 120 (hereinafter, these may be collectively referred to as "feeding sections 110, 120"), a conveying section 130, an image forming section 140, and a paper output tray 150. The feeding sections 110, 120 store a plurality of paper sheets M (sheets) in a stacked state before images are formed on them. The paper output tray 150 stores paper sheets M on which images have been formed.

[0011] Paper sheet M is an example of a sheet that is fed from feeding units 110 and 120, transported by transport unit 130, and on which an image is formed by image forming unit 140. However, the sheet is not limited to paper, and may be an overhead projector sheet, cloth, or the like. Inside image forming apparatus 100, a transport path R1 is formed, which is a space through which paper sheet M is transported. Transport path R1 is a path that runs from feeding units 110 and 120 to a position facing image forming unit 140, and then to paper output tray 150.

[0012] The feeding units 110 and 120 stack multiple sheets of paper M in a stacked state and supply (feed) the stacked sheets of paper M one by one to the conveying unit 130. More specifically, the feeding units 110 and 120 float and feed the topmost sheet of paper M from the stack. The detailed configuration of the feeding units 110 and 120 will be described later with reference to FIGS. 2 and 3.

[0013] Conveying unit 130 conveys paper M fed from feeding units 110 and 120 along conveying path R1. Specifically, conveying unit 130 conveys paper M stored in feeding units 110 and 120 along conveying path R1 to a position facing image forming unit 140. Furthermore, conveying unit 130 discharges paper M, on the surface of which an image has been formed by image forming unit 140, onto paper output tray 150 along conveying path R1.

[0014] The conveying section 130 includes a plurality of conveying rollers 131 and 132. The conveying rollers 131 and 132 are configured, for example, with a drive roller that rotates when the driving force of a motor is transmitted, and a driven roller that contacts the drive roller and rotates accordingly. The sheet M is conveyed along the conveying path R1 by the drive roller and the driven roller rotating while sandwiching the sheet M therebetween.

[0015] The transport roller 131 is disposed upstream in the transport direction from the image forming unit 140. The transport roller 132 is disposed downstream in the transport direction from the image forming unit 140. However, the installation positions of the transport rollers are not limited to the two locations shown in FIG.

[0016] The image forming unit 140 is disposed between the conveying rollers 131 and 132, facing the conveying path R1. The image forming unit 140 forms an image on the surface of the paper M conveyed by the conveying unit 130. The image forming unit 140 according to the embodiment forms an image on the paper M conveyed along the conveying path R1 by an electrophotographic method. However, the image forming method of the image forming unit 140 may also be an inkjet recording method in which an image is formed by ejecting ink onto the paper M.

[0017] More specifically, image forming unit 140 has a configuration in which photosensitive drums 141Y, 141M, 141C, and 141K (hereinafter collectively referred to as "photosensitive drums 141") of the respective colors are arranged along transfer belt 142, which is an endless moving means. That is, along transfer belt 142, on which an intermediate transfer image to be transferred to paper M fed from feed units 110 and 120 is formed, multiple photosensitive drums 141Y, 141M, 141C, and 141K are arranged in order from the upstream side in the conveying direction of transfer belt 142.

[0018] Toner stored in a toner bottle is supplied to the photosensitive drum 141. Then, a full-color image is formed by superimposing and transferring the images of each color developed with toner on the surface of the photosensitive drum 141 of each color onto the transfer belt 142. The full-color image formed on the transfer belt 142 is then transferred onto the paper M by a transfer roller 143 at a position closest to the conveyance path R1.

[0019] Furthermore, image forming unit 140 includes a fixing roller 144 arranged downstream of transfer roller 143 in the transport direction. Fixing roller 144 includes a drive roller driven by a motor and a driven roller that contacts and drives the drive roller. As the drive roller and driven roller rotate while nipping sheet M, the image transferred by transfer roller 143 is fixed to sheet M by heating and pressing sheet M.

[0020] Fig. 2 is a schematic diagram of the first feeding section 110. Fig. 3 is a diagram showing the operation of the first feeding section 110. The first feeding section 110 feeds sheets M one by one through feeding path R0 to conveyance path R1. As shown in Fig. 2, the first feeding section 110 mainly includes a sheet stacking section 111, a blower section 112, a suction feeding section 113, a clamping feeding section 114, a lifting mechanism 115, a lifting detection sensor 116, a feeding detection sensor 117, and a remaining amount detection sensor 118.

[0021] The sheet stacking unit 111 is a tray or cassette that can hold a plurality of sheets of paper M stacked on top of each other. The sheet stacking unit 111 is configured so that the user can replenish the sheets of paper M. The sheet stacking unit 111 is supported by the frame of the first feeding unit 110 so that it can be raised and lowered by a lifting mechanism 115 within a predetermined lifting range.

[0022] The air blowing section 112 is disposed above the sheet stacking section 111 and below the suction feeding section 113. The air blowing section 112 is disposed at a position where it can face the sheets M stacked in the sheet stacking section 111 in the horizontal direction. As shown in FIG. 3A, the air blowing section 112 blows air from the side of the sheets M stacked in the sheet stacking section 111, thereby floating the topmost sheet M.

[0023] The air blowing section 112 mainly includes, for example, a floating blower 112a and an air outlet 112b. The floating blower 112a generates air that floats the sheets M. The air outlet 112b blows the air generated by the floating blower 112a obliquely upward toward the sheets M stacked on the sheet stacking section 111. The sheet stacking section 111 is then raised and lowered by the lifting mechanism 115 so that the top sheet M is positioned on the path of the air blown from the air outlet 112b, thereby floating the top sheet M.

[0024] The suction feeding section 113 is disposed above the sheet stacking section 111, the air blowing section 112, and the lifting / lowering detection sensor 116. The suction feeding section 113 is disposed upstream in the feeding direction from the pinch feeding section 114 and the feeding detection sensor 117. The suction feeding section 113 adsorbs the sheet M floated by the air blowing section 112, and transports the sheet M in the feeding direction along a feeding path R0. The feeding path R0 is connected to a transport path R1.

[0025] The suction feed unit 113 mainly includes, for example, a drive pulley 113a, a driven pulley 113b, an endless circular belt 113c, a feed motor 113d, a suction port 113e, and a suction fan 113f. The drive pulley 113a and the driven pulley 113b are rotatably supported at positions spaced apart in the feed direction. The endless circular belt 113c is stretched over the drive pulley 113a and the driven pulley 113b. A plurality of through-holes are formed in the surface of the endless circular belt 113c. The feed motor 113d rotates the drive pulley 113a. The suction port 113e is disposed between the endless circular belt 113c and opens downward. The suction fan 113f sucks air below the suction feeding unit 113 through the suction port 113e and the through-holes of the endless circular belt 113c.

[0026] As shown in Fig. 3(B), an upward air flow is generated by driving the suction fan 113f. As a result, the sheet M floated by the blower 112 is adsorbed to the lower surface of the endless circular belt 113c. Also, as shown in Fig. 3(C), by driving the feed motor 113d, the drive pulley 113a (in other words, the endless circular belt 113c) rotates counterclockwise. As a result, the sheet M adsorbed to the lower surface of the endless circular belt 113c is supplied to the nip feed unit 114 along the feed path R0.

[0027] The nip feed unit 114 is disposed downstream in the feeding direction from the suction feed unit 113 and upstream in the feeding direction from the feeding detection sensor 117. The nip feed unit 114 feeds the paper M supplied from the suction feed unit 113 in the feeding direction along the feeding path R0. The nip feed unit 114 mainly includes, for example, a drive roller 114a, a driven roller 114b, and a feeding motor 114c.

[0028] The drive roller 114a and the driven roller 114b are each rotatably supported. The drive roller 114a and the driven roller 114b are in contact with each other with the feed path R0 sandwiched therebetween. The feed motor 114c rotates the drive roller 114a. The nip feed unit 114 then nip the sheet M that has entered between the drive roller 114a and the driven roller 114b between the drive roller 114a and the driven roller 114b and feeds it. As a result, the sheet M is fed to the transport path R1.

[0029] The lifting mechanism 115 lifts and lowers the sheet stacking portion 111. The lifting mechanism 115 mainly includes, for example, a lifting motor 115a and a drive force transmission unit that transmits the drive force of the lifting motor 115a to the sheet stacking portion 111. The drive force transmission unit may be configured, for example, with a rotatably supported pulley and a belt that is stretched around the pulley and has one end connected to the sheet stacking portion 111 and the other end connected to the output shaft of the lifting motor 115a. As shown in FIG. 3(D), the lifting mechanism 115 lifts the sheet stacking portion 111 by rotating the lifting motor 115a in a first direction. The lifting mechanism 115 also lowers the sheet stacking portion 111 by rotating the lifting motor 115a in a second direction opposite to the first direction.

[0030] The lifting / lowering detection sensor 116 is fixed to a detection position above the sheet stacking unit 111 and below the suction feeding unit 113. More specifically, the lifting / lowering detection sensor 116 is located above the sheet stacking unit 111, which is located at the upper end of the lifting / lowering range. The lifting / lowering detection sensor 116 is also arranged at a position where it can face the sheets M stacked on the sheet stacking unit 111 in the horizontal direction. The lifting / lowering detection sensor 116 detects that the sheets M stacked on the sheet stacking unit 111 are present at the detection position. The lifting / lowering detection sensor 116 determines that the sheets M are present at the detection position when, for example, the density of the sheets M in an area including the detection position is equal to or greater than a predetermined value.

[0031] The lifting / lowering detection sensor 116 is, for example, a reflective optical sensor including a light-emitting unit and a light-receiving unit. The light-emitting unit emits light in a horizontal direction from a detection position. The light-receiving unit receives light that is emitted from the light-emitting unit and reflected by the sheets M stacked in the sheet stacking unit 111. When the light-receiving unit of the lifting / lowering detection sensor 116 receives light, the lifting / lowering detection sensor 116 outputs a presence signal indicating that the sheets M are present at the detection position to the controller 160, which will be described later. On the other hand, when the light-receiving unit of the lifting / lowering detection sensor 116 does not receive light, the lifting / lowering detection sensor 116 stops outputting the presence signal to the controller 160.

[0032] The feeding detection sensor 117 is disposed downstream in the feeding direction from the suction feeding section 113 and the pinch feeding section 114. The feeding detection sensor 117 is disposed facing the feeding path R0. The feeding detection sensor 117 detects that the paper M has passed through the feeding path R0 (i.e., that the paper M has been fed appropriately).

[0033] The feeding detection sensor 117 is, for example, a reflective optical sensor equipped with a light-emitting unit and a light-receiving unit. The light-emitting unit emits light toward the feeding path R0. The light-receiving unit receives light that is emitted from the light-emitting unit and reflected by the paper M passing through the feeding path R0. When the light-receiving unit of the feeding detection sensor 117 receives light, the feeding detection sensor 117 outputs a feeding signal indicating that the paper M has been fed to the controller 160. On the other hand, when the light-receiving unit of the feeding detection sensor 117 does not receive light, the feeding detection sensor 117 stops outputting the feeding signal to the controller 160.

[0034] The remaining amount detection sensor 118 detects the remaining amount of paper sheets M stacked in the sheet stacking unit 111. The remaining amount of paper sheets M is indicated, for example, as a percentage of the maximum amount (maximum number of sheets) of paper sheets M that can be stacked in the sheet stacking unit 111, with 100% being the percentage. The remaining amount detection sensor 118 is, for example, a rotary encoder attached to the output shaft of the lift motor 115a. The remaining amount detection sensor 118 outputs a pulse signal corresponding to the amount of rotation of the lift motor 115a in the first direction to the controller 160 (see FIG. 4), which will be described later. However, the specific configuration of the remaining amount detection sensor 118 is not limited to the example described above, as long as it can detect the remaining amount of paper sheets M stacked in the sheet stacking unit 111.

[0035] The configuration of the second feeding section 120 according to this embodiment is common to that of the first feeding section 110. The components common to the feeding sections 110 and 120 are given reference numerals that share the suffix "x," such as "11x" for the first feeding section 110 and "12x" for the second feeding section 120. However, the specific configuration of the second feeding section 120 is not limited to the example described above. As another example, the second feeding section 120 may feed the paper M using a feed roller that rotates in contact with the topmost paper M stacked on the sheet stacking section 121. As yet another example, the second feeding section 120 may feed the paper M manually inserted by the user.

[0036] 4 is a diagram showing the hardware configuration of image forming apparatus 100. Image forming apparatus 100 includes a CPU (Central Processing Unit) 101 as a control means, a RAM (Random Access Memory) 102 as a memory, a ROM (Read Only Memory) 103 as a memory, an HDD (Hard Disk Drive) 104 as a memory, and an I / F 105 as an interface, all of which are connected via a common bus 109 as a communication means. CPU 101, RAM 102, ROM 103, and HDD 104 are examples of a controller 160.

[0037] The CPU 101 is a computing unit that controls the overall operation of the image forming apparatus 100. The RAM 102 is a volatile storage medium that can read and write information at high speed, and is used as a work area when the CPU 101 processes information. The ROM 103 is a read-only nonvolatile storage medium that stores programs such as firmware. The HDD 104 is a nonvolatile storage medium that can read and write information and has a large storage capacity, and stores an OS (Operating System), various control programs, application programs, etc.

[0038] Image forming apparatus 100 processes a control program stored in ROM 103, an information processing program (application program) loaded into RAM 102 from a storage medium such as HDD 104, and the like using the arithmetic functions of CPU 101. This processing constitutes a software control unit including various functional modules of image forming apparatus 100. The software control unit thus constituted is combined with hardware resources installed in image forming apparatus 100 to constitute functional blocks that realize the functions of image forming apparatus 100.

[0039] I / F 105 is an interface that connects feeding units 110 and 120, conveying unit 130, image forming unit 140, and operation panel 170 to common bus 109. That is, controller 160 controls the operations of feeding units 110 and 120, conveying unit 130, image forming unit 140, and operation panel 170 through I / F 105.

[0040] Operation panel 170 is a user interface that includes a display that displays current setting values, a selection screen, etc., and an operation unit (for example, a touch panel, push buttons, etc.) that accepts input operations from the user.

[0041] 4, feeding units 110 and 120, controller 160, I / F 105, and common bus 109 constitute feeding device 200. In other words, the present invention can be applied not only to image forming apparatus 100 but also to an independent feeding device 200.

[0042] 5 is a functional block diagram of the controller 160. The controller 160 mainly includes a first feeding processing unit 161, a second feeding processing unit 162, a parameter setting unit 163, an elevation processing unit 164, a remaining amount determination unit 165, and a try processing unit 166. The functional blocks 161 to 166 constituting the controller 160 are realized, for example, by the CPU 101 executing a program stored in memory. The functional blocks 161 to 166 shown in FIG. 5 operate in conjunction with each other to feed the paper M from either the feeding unit 110 or 120 to the transport path R1.

[0043] The first feeding processing unit 161 drives the floating blower 112a, the suction fan 113f, and the feeding motors 113d and 114c to cause the first feeding unit 110 to perform the feeding operation shown in Figures 3(A) to 3(C). The second feeding processing unit 162 drives the floating blower 122a, the suction fan 123f, and the feeding motors 123d and 124c to cause the second feeding unit 120 to perform the feeding operation.

[0044] 6 and 7, the parameter setting unit 163 sets parameters (e.g., lift amount, threshold value) used in the feeding process shown in FIGS. 8, 10, and 11. The lift amount indicates the amount of lift of the sheet stacking unit 111 per time. The threshold value is a value to be compared with the remaining sheet amount in the sheet stacking unit 111 detected by the remaining sheet amount detection sensor 118. In other words, the threshold value is the remaining sheet amount when the sheet stacking unit 111 has risen too much, causing the air blown from the air blowing unit 112 to be blocked by the sheet stacking unit 111 and preventing the air from reaching the sheets M. The processing of the parameter setting unit 163 will be described later with reference to FIGS. 6 and 7.

[0045] The lifting / lowering processing unit 164 causes the lifting mechanism 115 to lift the sheet stacking unit 111 based on the presence signal output from the lifting / lowering detection sensor 116 and the lifting amount set by the parameter setting unit 163. Furthermore, the lifting / lowering processing unit 164 causes the lifting mechanism 115 to lower the sheet stacking unit 111 when the sheet stacking unit 111 is replenished with paper M.

[0046] The remaining amount determination unit 165 determines the remaining amount of sheets M stacked in the sheet stacking unit 111 (remaining sheet amount) based on the pulse signal output from the remaining amount detection sensor 118 and a threshold value set by the parameter setting unit 163. The remaining amount determination unit 165 integrates the number of pulse signals output from the remaining amount detection sensor 118. Then, the remaining amount determination unit 165 calculates the remaining sheet amount based on the integrated number of pulse signals. In other words, the larger the integrated value of the pulse signals, the smaller the remaining sheet amount. In addition, the remaining amount determination unit 165 resets the integrated number of pulse signals when the sheet stacking unit 111 is lowered by the lifting / lowering processing unit 164.

[0047] The trial processing unit 166 causes the first feeding unit 110 to try a feeding operation based on an input operation from the user received through the operation panel 170, the remaining sheet amount determined by the remaining amount determination unit 165, and a feeding signal output from the feeding detection sensor 117. First, the trial processing unit 166 receives an input operation from the user through the operation panel 170 indicating whether or not to cause the first feeding unit 110 to try a feeding operation. After causing the first feeding unit 110 to try a feeding operation, the trial processing unit 166 determines whether or not the feeding operation has been completed successfully based on whether or not a feeding signal is output from the feeding detection sensor 117. Furthermore, if the trial processing unit 166 causes the first feeding unit 110 to try the feeding operation N times (N is an integer equal to or greater than 2) but no feeding signal is output from the feeding detection sensor 117, the trial processing unit 166 causes the second feeding unit 120 to perform the feeding operation instead of the first feeding unit 110.

[0048] FIG. 6 is a flowchart of parameter setting processing based on the thickness T of the paper M. The parameter setting unit 163 acquires the thickness T (mm) of the paper M stacked on the sheet stacking unit 111. The parameter setting unit 163 may acquire the thickness T by, for example, a sensor provided in the sheet stacking unit 111, or may cause the user to input the thickness T through the operation panel 170. Next, the parameter setting unit 163 compares the acquired thickness T of the paper M with predetermined threshold thicknesses Tth1, Tth2, Tth3, and Tth4 (S601 to S604). Note that the threshold thicknesses satisfy Tth1 < Tth2 < Tth3 < Tth4. Then, the parameter setting unit 163 sets the increase amount and the threshold according to the thickness T of the paper M stacked on the sheet stacking unit 111 (S605 to S609).

[0049] More specifically, when the thickness T of the paper M is less than the first threshold thickness Tth1 (S601: Yes), the parameter setting unit 163 sets the increase amount to Amm and sets the threshold to α% (S605). Also, when the thickness T of the paper M is greater than or equal to the first threshold thickness Tth1 and less than the second threshold thickness Tth2 (S602: Yes), the parameter setting unit 163 sets the increase amount to Bmm and sets the threshold to β% (S606). Also, when the thickness T of the paper M is greater than or equal to the second threshold thickness Tth2 and less than the third threshold thickness Tth3 (S603: Yes), the parameter setting unit 163 sets the increase amount to Cmm and sets the threshold to γ% (S607). Also, when the thickness T of the paper M is greater than or equal to the third threshold thickness Tth3 and less than the fourth threshold thickness Tth4 (S604: Yes), the parameter setting unit 163 sets the increase amount to Dmm and sets the threshold to δ% (S608). Further, when the thickness T of the paper M is greater than or equal to the fourth threshold thickness Tth4 (S604: No), the parameter setting unit 163 sets the increase amount to Emm and sets the threshold to ε% (S609). Then, the parameter setting unit 163 notifies the lifting and lowering processing unit 164 of the set increase amount and notifies the remaining amount determination unit 165 of the set threshold.

[0050] FIG. 7 is a flowchart of parameter setting processing based on the size of the paper M (e.g., B4, A4, letter, etc.). The parameter setting unit 163 acquires the size S of the paper M loaded on the sheet stacking unit 111. The parameter setting unit 163 may acquire the size S by, for example, a sensor provided in the sheet stacking unit 111, or may cause the user to input the size S through the operation panel 170. Next, the parameter setting unit 163 compares the acquired size S of the paper M with predetermined threshold sizes Sth1, Sth2, Sth3, and Sth4 (S701~S704). Note that the threshold sizes are such that Sth1 < Sth2 < Sth3 < Sth4. Then, the parameter setting unit 163 sets the amount of increase and the threshold according to the size S of the paper M loaded on the sheet stacking unit 111 (S705~S709).

[0051] More specifically, the parameter setting unit 163 sets the amount of increase to Amm and the threshold to α% in response to the size S of the paper M being less than the first threshold size Sth1 (S701: Yes) (S705). Also, the parameter setting unit 163 sets the amount of increase to Bmm and the threshold to β% in response to the size S of the paper M being greater than or equal to the first threshold size Sth1 and less than the second threshold size Sth2 (S702: Yes) (S706). Also, the parameter setting unit 163 sets the amount of increase to Cmm and the threshold to γ% in response to the size S of the paper M being greater than or equal to the second threshold size Sth2 and less than the third threshold size Sth3 (S703: Yes) (S707). Also, the parameter setting unit 163 sets the amount of increase to Dmm and the threshold to δ% in response to the size S of the paper M being greater than or equal to the third threshold size Sth3 and less than the fourth threshold size Sth4 (S704: Yes) (S708). Further, the parameter setting unit 163 sets the amount of increase to Emm and the threshold to ε% in response to the size S of the paper M being greater than or equal to the fourth threshold size Sth4 (S704: No) (S709). Then, the parameter setting unit 163 notifies the lifting and lowering processing unit 164 of the set amount of increase and notifies the remaining amount determination unit 165 of the set threshold.

[0052] In FIGS. 6 and 7, the ascending amount is set such that, for example, A < B < C < D < E. That is, the parameter setting unit 163 increases the ascending amount per operation of the sheet stacking unit 111 as the thickness T of the paper M is thicker or the size S of the paper M is larger. Also, in FIGS. 6 and 7, the threshold values are set such that, for example, α < β < γ < δ < ε. That is, the parameter setting unit 163 increases the threshold value compared with the remaining sheet amount as the thickness T of the paper M is thicker or the size S of the paper M is larger. Further, in the parameter setting process of FIGS. 6 and 7, only one of the ascending amount and the threshold value may be set (changed), and the other may be a predetermined fixed value.

[0053] FIG. 8 is a flowchart of the feeding process according to the present embodiment. FIG. 9 is a schematic diagram showing the states of the feeding units 110 and 120 during the feeding process. The controller 160 executes the feeding process at the timing when an image formation instruction is input to the image forming apparatus 100. The feeding process is executed by the first feeding process unit 161, the second feeding process unit 162, the elevating process unit 164, the remaining amount determination unit 165, and the retry process unit 166. On the other hand, the parameter setting process by the parameter setting unit 163 is assumed to be executed before the start of the feeding process.

[0054] First, the elevating process unit 164 determines whether or not a presence signal is output from the elevation detection sensor 116 (in other words, whether a sheet is detected by the elevation detection sensor 116) (S801). Then, in response to the fact that no presence signal is output from the elevation detection sensor 116 (S801: No), the elevating process unit 164 rotates the elevating motor 115a in the first direction to raise the sheet stacking unit 111 by the ascending amount set by the parameter setting unit 163 (S802), and executes the process of step S801 again. That is, the elevating process unit 164 raises the sheet stacking unit 111 until the paper M stacked on the sheet stacking unit 111 reaches the detection position.

[0055] Then, in response to the fact that a presence signal is output from the lifting / lowering detection sensor 116 (S801: Yes), the lifting / lowering processing unit 164 causes the remaining amount determination unit 165 to execute the processes of steps S803 and S804. Based on the integrated value of the pulse signal output from the remaining amount detection sensor 118, the remaining amount determination unit 165 determines whether or not paper sheets M are stacked on the sheet stacking unit 111 (S803) and whether or not the remaining amount of sheets on the sheet stacking unit 111 is less than the threshold value set by the parameter setting unit 163 (S804).

[0056] Then, in response to determining that the remaining number of sheets in the sheet stacking unit 111 is equal to or greater than the threshold (S803: No & S804: No), the remaining amount determination unit 165 causes the first feeding processing unit 161 to execute the process of step S805. In step S805, the first feeding processing unit 161 drives the floating blower 112a, the suction fan 113f, and the feeding motors 113d and 114c to cause the first feeding unit 110 to execute a feeding operation. As a result, as shown in FIGS. 3(A) to 3(C), one sheet of paper M is fed from the first feeding unit 110 to the conveying path R1. Then, the first feeding processing unit 161 causes the lifting processing unit 164 to execute the process of step S801.

[0057] That is, while the remaining number of sheets in the sheet stacking section 111 is equal to or greater than the threshold (S804: No), the controller 160 causes the first feeding section 110 to repeatedly perform the feeding operation (S805) while raising the sheet stacking section 111 (S802). As a result, as shown in the upper part of Fig. 9, the number of sheets M stacked on the sheet stacking section 111 gradually decreases, and the sheet stacking section 111 gradually rises.

[0058] Furthermore, in response to determining that the remaining amount of sheets in the sheet stacking unit 111 is greater than 0% and less than the threshold value (S803: No & S804: Yes), the remaining amount determination unit 165 causes the trial processing unit 166 to execute the process of step S806. The trial processing unit 166 assigns 1 to the number of trials stored in the RAM 102 or the HDD 104 (S806), and causes the first feeding processing unit 161 to execute the process of step S807.

[0059] In step S807, the first feeding processing unit 161 drives the floating blower 112a, the suction fan 113f, and the feeding motors 113d and 114c to cause the first feeding unit 110 to perform the feeding operation. That is, in response to determining that the number of remaining sheets in the sheet stacking unit 111 is less than the threshold (S804: No), the controller 160 causes the first feeding unit 110 to try to perform the feeding operation (S807). Then, the first feeding processing unit 161 causes the try processing unit 166 to perform the processing of step S808.

[0060] The trial processing unit 166 determines whether a feeding signal is output from the feeding detection sensor 117 (S808). In other words, the trial processing unit 166 determines whether the paper M has been fed to the transport path R1 by the feeding operation that the first feeding unit 110 was made to try in step S807 (S808). Then, in response to determining that a feeding signal is output from the feeding detection sensor 117 (S808: Yes), the trial processing unit 166 causes the lifting processing unit 164 to execute the process of step S801.

[0061] On the other hand, in response to determining that a feed signal is not output from the feed detection sensor 117 (S808: No), the try processing unit 166 determines whether the number of tries has reached N (S809). In response to determining that the number of tries is less than N (S809: No), the try processing unit 166 adds 1 to the number of tries (S810) and causes the first feeding processing unit 161 to execute the process of step S807. That is, the controller 160 causes the first feeding unit 110 to retry the feeding operation up to N times (S806 to S810) until a feed signal is output from the feed detection sensor 117.

[0062] Then, in response to determining that the number of tries has reached N (S809: Yes), the try processing unit 166 causes the second feeding processing unit 162 to execute the process of step S811. In step S811, the second feeding processing unit 162 causes the second feeding unit 120 to execute the feeding operation by driving the floating blower 122a, the suction fan 123f, and the feeding motors 123d and 124c. That is, in response to the fact that the feeding signal is not output from the feeding detection sensor 117 even though the first feeding unit 110 has tried the feeding operation N times (S808: No & S809: Yes), the controller 160 causes the second feeding unit 120 to feed the paper M instead of the first feeding unit 110 (S811), as shown in FIG.

[0063] Furthermore, in response to determining that no paper sheets M are stacked in the sheet stacking section 111 (S803: Yes), the remaining amount determining section 165 causes the second feeding processing section 162 to execute the process of step S811 without executing steps S804 to S810. Furthermore, the remaining amount determining section 165 may notify the user via the operation panel 170 that no paper sheets M are stacked in the sheet stacking section 111.

[0064] According to the above embodiment, for example, the following advantageous effects are achieved.

[0065] According to the above embodiment, when the remaining number of sheets in the sheet stacking unit 111 is less than the threshold (S804: Yes), the second feeding unit 120 is caused to perform the feeding operation instead of the first feeding unit 110 (S811). As a result, when the sheet stacking unit 111 approaches the endless circular belt 113c and it is difficult for the air blown from the air blowing unit 112 to reach the topmost sheet M, the feeding operation is switched from the first feeding unit 110 to the second feeding unit 120. As a result, the availability rate of the image forming apparatus 100 (feeding device 200) can be improved. On the other hand, when the remaining number of sheets in the sheet stacking unit 111 is equal to or greater than the threshold (S804: No), the first feeding unit 110 is caused to perform the feeding operation (S805), which prevents the user from having to replenish sheets M at an unnecessary time.

[0066] Furthermore, according to the above embodiment, when the remaining number of sheets in the sheet stacking unit 111 is less than the threshold value (S804: Yes), the first feeding unit 110 is made to retry the feeding operation up to N times (S806 to S810), so that it is possible to consume as much of the sheets M stacked in the sheet stacking unit 111 as possible before switching to the second feeding unit 120. This further prevents the user from having to replenish the sheets M at unnecessary times. Note that the maximum number of attempts N may be a predetermined fixed value, or may be set by the user via the operation panel 170.

[0067] Furthermore, according to the above embodiment, the rotary encoder attached to the output shaft of the lifting motor 115a is used as the remaining amount detection sensor 118, so the number of parts of the image forming apparatus 100 can be reduced compared to when the remaining amount detection sensor 118 is provided separately from the rotary encoder.

[0068] Furthermore, according to the above embodiment, by making the increase amount and threshold value variable depending on the thickness T or size S of the paper M, it is possible to use an appropriate increase amount and threshold value depending on the type of paper M. However, the increase amount and threshold value may be predetermined fixed values, or may be set by the user via the operation panel 170.

[0069] [Variation 1] The feeding process according to Modification 1 will be described with reference to Fig. 10. Fig. 10 is a flowchart of the feeding process according to Modification 1. Note that detailed description of commonalities with the above embodiment will be omitted, and the description will focus on differences. The feeding process shown in Fig. 10 differs from the feeding process shown in Fig. 8 in that steps S806 and S809 to S810 are omitted.

[0070] In response to determining that the number of remaining sheets in the sheet stacking unit 111 is less than the threshold value (S804: Yes), the controller 160 according to the first modification causes the first feeding unit 110 to attempt a feeding operation only once (S807). Then, in response to determining that a feeding signal is not output from the feeding detection sensor 117 (S808: No), the controller 160 causes the second feeding unit 120 to feed the sheets instead of the first feeding unit 110 (S811).

[0071] [Variation 2] The feeding process according to Modification 2 will be described with reference to Fig. 11. Fig. 11 is a flowchart of the feeding process according to Modification 2. Note that detailed description of the points in common with the above embodiment will be omitted, and the description will focus on the points of difference. The feeding process shown in Fig. 11 differs from the feeding process shown in Fig. 8 in that steps S806 to S810 are omitted.

[0072] In response to determining that the remaining number of sheets in the sheet stacking unit 111 is less than the threshold value (S804: Yes), the controller 160 according to the second modification causes the second feeding unit 120 to feed the sheets (S811) without causing the first feeding unit 110 to try a feeding operation. That is, in the second modification, the try processing unit 166 is omitted.

[0073] According to the second modification, when the sheet stacking section 111 is raised too high and there is a high possibility that the feeding operation by the first feeding section 110 will fail (S804: Yes), the first feeding section 110 is not made to attempt a feeding operation, and the second feeding section 120 is made to feed the paper M (S811). This makes it possible to reduce time loss in the feeding process.

[0074] 8 or 10 (causing the first feeding section 110 to try a feeding operation) or the feeding process shown in Fig. 11 (causing the second feeding section 120 to feed a sheet without causing the first feeding section 110 to try a feeding operation) may be switched in accordance with an input operation received through the operation panel 170. This makes it possible to switch between enabling and disabling the first feeding section 110 to try a feeding operation in accordance with the user's usage environment.

[0075] Each function of the above-described embodiments can be realized by one or more processing circuits. Here, the term "processing circuit" in this specification includes a processor programmed to perform each function by software, such as a processor implemented by an electronic circuit, as well as devices such as an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or a conventional circuit module designed to perform each function described above.

[0076] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist thereof. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed content. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0077] 100: Image forming device 101: CPU 102: RAM 103:ROM 104: HDD 105: Interface 109: Common bus 110: 1st feeding section 111,121: Sheet stacking area 112: Ventilation section 112a, 122a: Floating blower 112b: Ventilation outlet 113: Adsorption feeding section 113a: Drive pulley 113b: driven pulley 113c: Endless circular belt 113d, 123d: Feed motor 113e: Suction port 113f, 123f: Suction fan 114: Gripping feeding section 114a: drive roller 114b: driven roller 114c,124c: Feeding motor 115: Lifting mechanism 115a: Lifting motor 116: Lift detection sensor 117: Feed detection sensor 118: Remaining amount detection sensor 120: 2nd feeding section 130: Transport unit 131, 132: Transport roller 140: Image forming unit 141, 141C, 141K, 141M, 141Y: Photosensitive drum 142: Transfer belt 143: Transfer roller 144: Fuser roller 150: Paper output tray 160: Controller 161: First feeding processing section 162: Second feeding processing section 163: Parameter setting section 164: Lifting processing section 165: Remaining amount determination unit 166: Trie processing unit 170: Operation panel 200:Feeding device [Prior art documents] [Patent documents]

[0078] [Patent Document 1] Japanese Patent Application Publication No. 09-301574

Claims

1. a first feeding section that floats and feeds a sheet; a second feeding section that feeds sheets; a controller that causes the first feeding unit and the second feeding unit to feed sheets, The first feeding section a sheet stacking section on which a plurality of sheets are stacked; an air blowing unit that blows air from the side of the plurality of sheets stacked on the sheet stacking unit to lift up the top sheet; a suction feeding section disposed above the sheet stacking section, which suctions the sheet floated by the air blowing section and feeds the sheet in a feeding direction; a remaining amount detection sensor that detects the remaining amount of sheets stacked in the sheet stacking section; a feeding detection sensor that detects the sheet fed by the suction feeding unit, The controller determining whether the remaining number of sheets in the first feeding unit is less than a threshold value; In response to determining that the remaining amount of sheets is equal to or greater than the threshold, the first feeding unit executes a feeding operation of feeding the sheets floated by the air blowing unit to the suction feeding unit, When the sheet is not detected by the feeding detection sensor, the second feeding unit is caused to feed the sheet instead of the first feeding unit. In response to determining that the remaining amount of sheets in the first feeding unit is less than the threshold value, the first feeding unit is caused to retry the feeding operation up to N times (N is an integer of 2 or more) until a sheet is detected by the feeding detection sensor; A feeding device characterized in that, when the first feeding section performs the feeding operation N times but the feeding detection sensor does not detect a sheet, the second feeding section is made to feed the sheet instead of the first feeding section.

2. a first feeding section that floats and feeds a sheet; a second feeding section that feeds sheets; an operation unit that accepts input operations from a user; a controller that causes the first feeding unit and the second feeding unit to feed sheets, The first feeding section a sheet stacking section on which a plurality of sheets are stacked; an air blowing unit that blows air from the side of the plurality of sheets stacked on the sheet stacking unit to lift up the top sheet; a suction feeding section disposed above the sheet stacking section, which suctions the sheet floated by the air blowing section and feeds the sheet in a feeding direction; a remaining amount detection sensor that detects the remaining amount of sheets stacked in the sheet stacking section; a feeding detection sensor that detects the sheet fed by the suction feeding unit, The controller determining whether the remaining number of sheets in the first feeding unit is less than a threshold value; In response to determining that the remaining amount of sheets is equal to or greater than the threshold, the first feeding unit executes a feeding operation of feeding the sheets floated by the air blowing unit to the suction feeding unit, When the sheet is not detected by the feeding detection sensor, the second feeding unit is caused to feed the sheet instead of the first feeding unit. A feeding device characterized in that, when it is determined that the remaining sheet amount in the first feeding section is less than the threshold value, the feeding device switches between having the first feeding section attempt the feeding operation or having the second feeding section feed the sheet without having the first feeding section attempt the feeding operation, depending on the input operation received through the operation section.

3. The first feeding section a lifting motor for lifting and lowering the sheet stacking unit; a lifting / lowering detection sensor disposed at a detection position between the sheet stacking section and the suction feeding section, the lifting / lowering detection sensor detecting the presence of sheets stacked on the sheet stacking section; the controller causes the lifting motor to lift the sheet stacking unit in response to the lifting detection sensor not detecting a sheet; 3. The feeding device according to claim 1, wherein the remaining amount detection sensor is a rotary encoder that outputs a pulse signal corresponding to the rotation amount of the lifting motor to the controller.

4. 4. The feeding device according to claim 3, wherein the controller changes the amount of lifting of the sheet stacking portion per movement by the lifting motor in accordance with the thickness or size of the sheets stacked on the sheet stacking portion.

5. 5. The feeding device according to claim 1, wherein the controller changes the threshold value in accordance with a thickness or size of the sheets stacked on the sheet stacking section.

6. A feeding device according to any one of claims 1 to 5; an image forming apparatus comprising: an image forming unit that forms an image on the sheet fed by the feeding device;

Images