Sheet conveying device, image forming apparatus, and acquisition method

Abstract

To provide a sheet conveyance device, an image forming apparatus, and an acquisition method capable of suppressing deterioration of acquisition accuracy of a conveyance speed of a sheet.SOLUTION: The image forming apparatus 100 includes a lift plate configured to lift a sheet stack, a sheet feed portion including a pickup roller configured to rotate in contact with an upper surface of the sheet stack lifted by the lift plate and configured to feed a sheet in contact with the pickup roller to a conveyance path, a sheet sensor 25 configured to detect the sheet fed by the sheet feed portion in the conveyance path, and an acquisition processing portion 42 configured to acquire, only when the sheet stack is lifted by the lift plate, speed information on a conveyance speed of the sheet fed by the sheet feed portion using the sheet sensor 25.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device, an image forming apparatus, and an acquisition method. [Background technology]

[0002] An image forming apparatus such as a multifunction peripheral includes a sheet transport device that transports sheets on which an image is to be formed. For example, the sheet transport device includes a lift unit, a sheet supply unit, and a detection unit. The lift unit lifts a stack of sheets. The sheet supply unit includes a transport member that rotates in contact with the upper surface of the stack of sheets lifted by the lift unit, and supplies the sheets that contact the transport member to a transport path. The detection unit detects the sheets supplied by the sheet supply unit in the transport path.

[0003] Further, there is known a sheet conveying device that uses the detection unit to measure the conveying speed of the sheet by the sheet supply unit (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-132413 Summary of the Invention [Problem to be solved by the invention]

[0005] In the sheet conveying device, the sheet below the sheet to be conveyed by the conveying member may be pulled by the sheet to be conveyed and fed out from the sheet stack.

[0006] Here, if the detection unit is used to measure the sheet transport speed in a state in which the sheet is fed out and protruding from the sheet stack, the accuracy of obtaining the sheet transport speed decreases.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet conveying device, an image forming apparatus, and an acquisition method that can suppress a decrease in the accuracy of acquiring the sheet conveying speed. [Means for solving the problem]

[0008] According to one aspect of the present invention, a sheet transport device includes a lift unit, a sheet supply unit, a detection unit, and an acquisition processing unit. The lift unit lifts a sheet stack. The sheet supply unit includes a transport member that rotates in contact with an upper surface of the sheet stack lifted by the lift unit, and supplies the sheet contacting the transport member to a transport path. The detection unit detects the sheet supplied by the sheet supply unit in the transport path. The acquisition processing unit uses the detection unit to acquire speed information regarding the transport speed of the sheet by the sheet supply unit only when the sheet stack is lifted by the lift unit.

[0009] An image forming apparatus according to another aspect of the present invention includes the sheet conveying device and an image forming section, the image forming section forming an image on the sheet conveyed by the sheet conveying device.

[0010] According to another aspect of the present invention, there is provided an acquisition method that is executed by a sheet conveying device that includes a lift unit that lifts a sheet stack, a sheet supply unit that includes a conveying member that rotates in contact with an upper surface of the sheet stack lifted by the lift unit and that supplies the sheet that contacts the conveying member to a conveying path, and a detection unit that detects the sheet that is supplied by the sheet supply unit in the conveying path, and the acquisition method includes an acquisition step in which, only when the sheet stack is lifted by the lift unit, the detection unit is used to acquire speed information regarding the conveying speed of the sheet by the sheet supply unit. [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress a decrease in accuracy in obtaining the sheet conveying speed. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the appearance of an image forming apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the internal configuration of the image forming apparatus according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a block diagram showing the system configuration of the image forming apparatus according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the configuration of the sheet supply unit of the image forming apparatus according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a flowchart showing an example of the reset process executed in the image forming apparatus according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing an example of the first paper feeding process executed in the image forming apparatus according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart showing an example of a speed information acquisition process executed in the image forming apparatus according to the first embodiment of the present invention. [Figure 8] FIG. 8 is a block diagram showing the system configuration of an image forming apparatus according to the second embodiment of the present invention. [Figure 9] FIG. 9 is a flowchart showing an example of the second paper feed process executed in the image forming apparatus according to the second embodiment of the present invention. [Figure 10] FIG. 10 is a block diagram showing the system configuration of an image forming apparatus according to the third embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing the configuration of a sheet supply unit of an image forming apparatus according to the third embodiment of the present invention. [Figure 12] FIG. 12 is a flowchart showing an example of a third paper feed process executed by an image forming apparatus according to the third embodiment of the present invention. [Figure 13] FIG. 13 is a flowchart showing an example of a transport amount acquisition process executed in an image forming apparatus according to the third embodiment of the present invention. [Figure 14] FIG. 14 is a diagram showing an example of a setting failure state. [Figure 15] FIG. 15 is a diagram illustrating an example of a setting failure state. [Figure 16] FIG. 16 is a diagram showing the configuration of a sheet supply unit of the image forming apparatus according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of a specific embodiment of the present invention and does not limit the technical scope of the present invention.

[0014] [First embodiment] First, the configuration of an image forming apparatus 100 according to a first embodiment of the present invention will be described with reference to Figs. 1 to 4. Fig. 1 is a perspective view showing the appearance of the image forming apparatus 100. Fig. 2 is a cross-sectional view showing the internal configuration of the image forming apparatus 100. Fig. 4 is an enlarged view of the sheet supply unit 28 shown in Fig. 2.

[0015] For ease of explanation, the vertical direction in the installation state where image forming apparatus 100 is usable (the state shown in FIG. 1) is defined as the up-down direction D1. Also, the front-to-back direction D2 is defined with the face on the left front side of image forming apparatus 100 on the paper shown in FIG. 1 as the front (front face). Also, the left-to-right direction D3 is defined with the front face of image forming apparatus 100 in the installation state as the reference point.

[0016] Image forming apparatus 100 is a multifunction peripheral having multiple functions such as a scan function, a print function, a fax function, and a copy function. Note that the present invention may be applied to image forming apparatuses such as printers, fax machines, and copy machines.

[0017] As shown in FIG. 3, the image forming apparatus 100 includes an ADF (Auto Document Feeder) 1, an image reading unit 2, an image forming unit 3, a paper feeding unit 4, an operation display unit 5, a storage unit 6, and a control unit .

[0018] The image forming unit 3, paper feed unit 4, storage unit 6, and control unit 7 are housed in a housing 100A of the image forming apparatus 100 (see FIGS. 1 and 2). The housing 100A is formed in a substantially rectangular parallelepiped shape. The ADF 1 and image reading unit 2 are provided on the upper side of the housing 100A (see FIGS. 1 and 2). The operation display unit 5 is provided on the front side of the housing 100A (see FIG. 1).

[0019] The ADF 1 transports a document whose image is to be read by the image reading unit 2. The ADF 1 includes a document setting unit, a plurality of transport rollers, a document presser, and a paper discharge unit.

[0020] The image reading unit 2 reads an image of a document. That is, the image reading unit 2 realizes the scanning function. The image reading unit 2 includes a document table, a light source, a plurality of mirrors, an optical lens, and a CCD (Charge Coupled Device).

[0021] The image forming unit 3 forms an image based on image data on a sheet SH1 (see FIG. 2) supplied from the paper feed unit 4. In other words, the image forming unit 3 realizes the print function. Specifically, the image forming unit 3 forms an image by electrophotography. The image forming unit 3 includes a photosensitive drum, a charging device, an optical scanning unit (LSU), a developing device, a transfer device, a cleaning device, and a fixing device.

[0022] The operation display unit 5 is a user interface of the image forming apparatus 100. The operation display unit 5 includes a display unit and an operation unit. The display unit displays various information in response to control instructions from the control unit 7. For example, the display unit is a flat panel display such as a liquid crystal display. The operation unit inputs various information to the control unit 7 in response to user operations. For example, the operation unit includes operation keys and a touch panel.

[0023] The storage unit 6 is a non-volatile storage device, such as a flash memory.

[0024] The control unit 7 performs overall control of the image forming apparatus 100. As shown in FIG. 3, the control unit 7 includes a CPU 11, a ROM 12, and a RAM 13. The CPU 11 is a processor that executes various types of arithmetic processing. The ROM 12 is a non-volatile storage device that pre-stores information such as control programs for causing the CPU 11 to execute various processes. The RAM 13 is a volatile or non-volatile storage device used as a temporary storage memory (work area) for the various processes executed by the CPU 11. In the control unit 7, the CPU 11 executes various control programs pre-stored in the ROM 12. In this way, the control unit 7 performs overall control of the image forming apparatus 100. The control unit 7 may be configured with an electronic circuit such as an integrated circuit (ASIC). The control unit 7 may also be a control unit provided separately from a main control unit that performs overall control of the image forming apparatus 100.

[0025] The paper feed unit 4 supplies the sheet SH1 (see FIG. 2) to the image forming unit 3.

[0026] As shown in FIGS. 2 and 3, the paper feed unit 4 includes a paper feed cassette 21, a pickup roller 22, a paper feed roller 23, a separation roller 24, a sheet sensor 25, a pull-out sensor 26, and a conveyance path 27.

[0027] A stack of sheets SB1 (see FIG. 2) is placed in the paper feed cassette 21. For example, the sheet stack SB1 including sheets SH1 such as paper, coated paper, postcards, envelopes, and transparencies is placed in the paper feed cassette 21. As shown in FIGS. 1 and 2, the paper feed cassette 21 is provided at the bottom of the housing 100A. The paper feed cassette 21 is provided so as to be removable from the housing 100A in a removal direction D4 (see FIG. 1) along the front-rear direction D2. The paper feed cassette 21 stores the stack of sheets SB1. The paper feed cassette 21 is provided so as to be detachable from the housing 100A. The paper feed cassette 21 is an example of a sheet storage section of the present invention.

[0028] As shown in FIG. 2, the paper feed cassette 21 includes a lift plate 31, a lifting mechanism 32, an end cursor 33, and a pair of side cursors .

[0029] The lift plate 31 lifts the sheet stack SB1 (see FIG. 2) placed in the sheet cassette 21. The lift plate 31 is a flat member provided at the bottom of the sheet cassette 21. The sheet stack SB1 is placed on the upper surface of the lift plate 31. The lift plate 31 is provided rotatable around a rotation shaft 31A (see FIG. 2) extending in the front-rear direction D2. Specifically, the right end of the lift plate 31 is supported rotatable around the rotation shaft 31A. The lift plate 31 is an example of a lift unit of the present invention.

[0030] The lifting mechanism 32 raises and lowers the lift plate 31. As shown in FIG. 2, the lifting mechanism 32 includes a rotating shaft 32A and a push-up plate 32B. The rotating shaft 32A extends in the front-rear direction D2. The push-up plate 32B extends from the rotating shaft 32A in a direction perpendicular to the extension direction of the rotating shaft 32A. The push-up plate 32B is formed in the shape of a long flat plate in the front-rear direction D2. The rotating shaft 32A and the push-up plate 32B are provided below the lift plate 31.

[0031] The rear end of the rotation shaft 32A is connected to a motor (not shown) provided outside the sheet cassette 21 via a joint (not shown) provided outside the sheet cassette 21. The rotation shaft 32A and the lifting plate 32B receive a rotational driving force supplied from the motor via the joint and rotate in a second rotation direction D7 shown in FIG. 4. When the rotation shaft 32A and the lifting plate 32B rotate in the second rotation direction D7, the lifting plate 31 is pushed up by the lifting plate 32B and rotates in a first rotation direction D6 (see FIG. 4) shown in FIG. 4. As a result, the sheet stack SB1 placed on the upper surface of the lifting plate 31 is lifted upward.

[0032] The joint portion is restricted from rotating in the direction opposite to the second rotation direction D7. For example, the joint portion includes a ratchet mechanism that restricts the joint portion from rotating in the direction opposite to the second rotation direction D7. By restricting the joint portion from rotating in the direction opposite to the second rotation direction D7, the rotation of the rotation shaft 32A engaged with the joint portion is also restricted in the direction opposite to the second rotation direction D7. This restricts the lift plate 31 from descending due to its own weight.

[0033] When the sheet cassette 21 is pulled out from the housing 100A in the pulling-out direction D4, the engagement between the rotation shaft 32A and the joint portion is released, thereby releasing the joint portion from restricting the rotation of the rotation shaft 32A and the lift plate 32B in the direction opposite to the second rotation direction D7, and the lift plate 31 descends under its own weight.

[0034] The end cursor 33 is provided so as to be movable along the sheet conveying direction D5 shown in Fig. 4. The end cursor 33 adjusts the position of the sheet bundle SB1 in the sheet conveying direction D5 by abutting the sheet bundle SB1 placed in the sheet feed cassette 21 against a wall surface 21A (see Fig. 4) on the downstream side of the sheet feed cassette 21 in the sheet conveying direction D5. The pair of side cursors 34 are provided so as to be interlocked so as to move toward or away from each other along the width direction of the sheets SH1, which is perpendicular to the sheet conveying direction D5. The pair of side cursors 34 adjust the position of the sheets SH1 in the width direction by sandwiching and holding the sheet bundle SB1 placed in the sheet feed cassette 21.

[0035] As shown in FIGS. 2 and 4, the pickup roller 22 is provided above the lift plate 31. The pickup roller 22 rotates while contacting the upper surface of the sheet stack SB1 lifted by the lift plate 31, thereby transporting the uppermost sheet SH1 (see FIG. 2) of the sheet stack SB1 to the separation section 28A (see FIG. 4). Here, the separation section 28A is a nip formed between the paper feed roller 23 and the separation roller 24. The pickup roller 22 transports the sheet SH1 in a sheet transport direction D5 (see FIG. 4). The sheet transport direction D5 is a direction perpendicular to the front-rear direction D2. The pickup roller 22 is an example of a transport member of the present invention.

[0036] Specifically, the pickup roller 22 is rotatable about an axis extending in the front-rear direction D2. The pickup roller 22 rotates by receiving a rotational driving force supplied from a motor (not shown) while in contact with the upper surface of the sheet SH1. As a result, the pickup roller 22 applies a conveying force in the sheet conveying direction D5 to the sheet SH1 in contact with the pickup roller 22.

[0037] The pickup roller 22, the paper feed roller 23, and the separation roller 24 constitute a sheet supply unit 28 (see FIGS. 2 and 4) that supplies the sheet SH1 that comes into contact with the pickup roller 22 to a conveying path 27 (see FIG. 2). The conveying path 27 is a passage along which the sheet SH1 moves from the sheet supply unit 28 to the image forming unit 3.

[0038] 2 and 4, the paper feed roller 23 is provided downstream in the sheet conveyance direction D5 of the pickup roller 22. The paper feed roller 23 comes into contact with the upper surface of the sheet SH1 (see FIG. 2) conveyed by the pickup roller 22, and conveys the sheet SH1 beyond the detection position of the sheet sensor 25 (see FIG. 2). The paper feed roller 23 conveys the sheet SH1 in the sheet conveyance direction D5.

[0039] Specifically, the paper feed roller 23 is rotatable about an axis extending in the front-rear direction D2. The paper feed roller 23 rotates by receiving a rotational driving force supplied from a motor (not shown) while in contact with the upper surface of the sheet SH1. As a result, the paper feed roller 23 applies a conveying force in the sheet conveying direction D5 to the sheet SH1 in contact with the paper feed roller 23.

[0040] 2 and 4, separation roller 24 is provided below paper feed roller 23 and facing paper feed roller 23. Separation roller 24 forms separation section 28A (see FIG. 4) between separation roller 24 and paper feed roller 23. Separation section 28A separates sheet SH11 (see FIG. 16) conveyed by pickup roller 22 from another sheet SH12 (see FIG. 16) accompanying sheet SH11.

[0041] Specifically, the separation roller 24 has a shaft 24A (see FIG. 4) extending in the front-rear direction D2. The separation roller 24 is fixed to the shaft 24A and rotates integrally with the shaft 24A. The shaft 24A is rotatably supported by a bearing (not shown) provided inside the housing 100A. The bearing is biased toward the paper feed roller 23 by a biasing member (not shown), such as a coil spring, provided inside the housing 100A. This biases the separation roller 24 toward the paper feed roller 23, and a nip portion that holds the sheet SH1 between the separation roller 24 and the paper feed roller 23, i.e., a separation portion 28A, is formed.

[0042] When only one sheet SH1 is present in the separation section 28A, the separation roller 24 is driven to rotate in a rotation direction D8 shown in FIG. 4 by a force transmitted from the sheet SH1 conveyed by the sheet feed roller 23. Furthermore, when sheets SH11 and SH12 (see FIG. 16) are present in the separation section 28A, the separation roller 24 is restricted from rotating in the rotation direction D8. For example, the sheet supply section 28 includes a torque limiter that restricts the rotation of the shaft 24A in the rotation direction D8 when the torque transmitted to the shaft 24A in the rotation direction D8 is less than a predetermined value. When sheets SH11 and SH12 are present in the separation section 28A, the rotation of the separation roller 24 in the rotation direction D8 is restricted, and therefore, the movement of the sheet SH12 in contact with the separation roller 24 in the sheet conveyance direction D5 is restricted due to contact friction with the separation roller 24. As a result, as the sheet SH11 contacting the pickup roller 22 is conveyed, another sheet SH12 moving together with the sheet SH11 is separated from the sheet SH11.

[0043] As shown in FIG. 2, the sheet sensor 25 is provided downstream of the paper feed roller 23 in the sheet conveying direction D5. The sheet sensor 25 detects the sheet SH1 supplied by the sheet supply unit 28 in the conveying path 27. For example, the sheet sensor 25 includes an actuator that is moved by contact with the sheet SH1, and a reflective or transmissive optical sensor that detects the movement of the actuator. In the image forming apparatus 100, the timing of supplying the next sheet SH1 by the sheet supply unit 28 is determined based on the timing of detection of the sheet SH1 by the sheet sensor 25. The sheet sensor 25 is an example of a detection unit of the present invention.

[0044] The withdrawal sensor 26 detects the withdrawal of the sheet cassette 21 from the housing 100A. For example, the withdrawal sensor 26 includes a push switch that changes from an ON state to an OFF state in response to the withdrawal of the sheet cassette 21 from the housing 100A.

[0045] Incidentally, a sheet conveying device is known that uses the sheet sensor 25 to measure the conveying speed of the sheet SH1 by the sheet supply unit .

[0046] In the image forming apparatus 100, sheet SH3 (see FIG. 4) below sheet SH2 (see FIG. 4) to be conveyed by the pickup roller 22 may be pulled by sheet SH2 and fed out of the sheet stack SB1 (see FIG. 4). That is, sheet SH3 to be conveyed next by the pickup roller 22 may move downstream in the sheet conveying direction D5 from the reference position P1 (see FIG. 4). The reference position P1 is the position where the leading edge of the uppermost sheet SH1 in the sheet stack SB1 is located when the sheet stack SB1 is lifted by the lift plate 31.

[0047] When the sheet sensor 25 is used to measure the conveying speed of the sheet SH1 by the sheet supply unit 28 in a state where the sheet SH1 is fed out from the sheet stack SB1, the accuracy of obtaining the conveying speed decreases.

[0048] In contrast to this, in the image forming apparatus 100 according to the first embodiment of the present invention, it is possible to suppress a decrease in the accuracy of obtaining the conveying speed of the sheet SH1, as will be described below.

[0049] [Configuration of control unit 7] Next, the configuration of the control unit 7 will be described with reference to FIG.

[0050] 3, the control unit 7 includes a displacement processing unit 41, an acquisition processing unit 42, a setting processing unit 43, a determination processing unit 44, and a notification processing unit 45. An apparatus including the paper feed unit 4 and the control unit 7 is an example of a sheet conveying apparatus of the present invention.

[0051] Specifically, a paper feed control program for causing the CPU 11 of the control unit 7 to execute a reset process (see the flowchart in FIG. 5) and a first paper feed process (see the flowchart in FIG. 6), which will be described later, is stored in advance in the ROM 12 of the control unit 7. The paper feed control program may be recorded on a computer-readable recording medium such as a CD, DVD, or flash memory, and may be read from the recording medium and installed in a storage device such as the memory unit 6.

[0052] The control unit 7 executes the paper feed control program stored in the ROM 12 using the CPU 11, thereby functioning as each of the above-mentioned processing units.

[0053] Note that some or all of the processing units included in the control unit 7 may be configured with electronic circuits. The paper feed control program may also be a program for causing multiple processors to function as the processing units included in the control unit 7.

[0054] The displacement processing unit 41 displaces the sheet stack SB1 placed in the sheet cassette 21 to a position where the sheet stack SB1 comes into contact with the pickup roller 22 using the lift plate 31 when a predetermined specific timing arrives.

[0055] For example, the specific timing is the timing of executing the first image forming process after the paper feed cassette 21 is pulled out from the housing 100A. The image forming process is a process of forming an image on a sheet SH1 supplied by the paper feed unit 4 using the image forming unit 3.

[0056] The acquisition processing unit 42 acquires speed information relating to the conveying speed of the sheet SH1 by the sheet supply unit 28 using the sheet sensor 25 only when the sheet stack SB1 is lifted by the lift plate 31.

[0057] Here, the speed information is the conveying speed of the sheet SH1 by the sheet supply unit 28. Note that the speed information may also be the elapsed time from when the sheet supply unit 28 starts to supply the sheet SH1 to when the sheet sensor 25 detects the sheet SH1.

[0058] Specifically, the acquisition processing unit 42 measures the elapsed time from when the sheet supply unit 28 starts supplying the sheet SH1 to when the sheet sensor 25 detects the sheet SH1, and calculates the conveying speed of the sheet SH1 by the sheet supply unit 28 based on the measurement result and a specific conveying distance from a reference position P1 (see FIG. 4) to the detection position. The specific conveying distance is the distance from the reference position P1 to the detection position on the conveying path of the sheet SH1. The specific conveying distance may be stored in advance in the storage unit 6 or the ROM 12.

[0059] For example, the acquisition processing unit 42 stores the acquired speed information in association with the acquisition date and time of the speed information and the type of sheet SH1 conveyed when the speed information was acquired in a predetermined second storage area of ​​the storage unit 6. In this specification, the "type of sheet SH1" refers to a group identified by either the size or the material of the sheet SH1, or a combination of both.

[0060] For example, the acquisition processing unit 42 acquires the speed information when the lifting of the sheet stack SB1 by the lift plate 31 is the first lifting after the sheet cassette 21 is attached to the housing 100A.

[0061] For example, the acquisition processing unit 42 acquires the speed information every time the lift plate 31 lifts the sheet stack SB1.

[0062] For example, the acquisition processing unit 42 acquires the speed information when the first sheet SH1 is supplied after the sheet stack SB1 is lifted by the lift plate 31.

[0063] The acquisition processing unit 42 may acquire the speed information when the second or subsequent sheet SH1 is supplied after the sheet stack SB1 is lifted by the lift plate 31.

[0064] The setting processing unit 43 sets the initial speed information based on the result of acquisition by the acquisition processing unit 42 .

[0065] For example, when the speed information is acquired by the acquisition processing unit 42 and satisfies a predetermined setting condition, the setting processing unit 43 sets the initial speed information.

[0066] For example, the set condition is that the cumulative number of times that sheet SH1 has been supplied by sheet supply unit 28 is less than a predetermined reference number. The cumulative number of times that sheet SH1 has been supplied by sheet supply unit 28 may be counted up by control unit 7 each time sheet SH1 is supplied by sheet supply unit 28. The cumulative number of times that sheet SH1 has been supplied by sheet supply unit 28 may be reset in response to a predetermined operation on operation display unit 5, such as during maintenance of sheet supply unit 28. The contents stored in the second storage area of ​​storage unit 6 may be erased when the cumulative number of times that sheet SH1 has been supplied by sheet supply unit 28 is reset.

[0067] For example, the setting processing unit 43 sets the initial speed information for each type of sheet SH1.

[0068] For example, when the speed information is acquired by the acquisition processing unit 42 and the setting conditions are satisfied, the setting processing unit 43 sets the average value of the speed information stored in the second memory area of ​​the memory unit 6 that is common to the speed information last stored for the type of associated sheet SH1 as the initial speed information corresponding to the type of sheet SH1.

[0069] The setting condition may be that the cumulative number of times the sheet SH1 has been supplied by the sheet supply unit 28 is less than the reference number of times, and that the initial speed information corresponding to the type of the sheet SH1 conveyed when the speed information is acquired by the acquisition processing unit 42 has not yet been set. In this case, when the speed information is acquired by the acquisition processing unit 42 and the setting condition is satisfied, the setting processing unit 43 sets the acquired speed information as the initial speed information corresponding to the type of the sheet SH1 conveyed when the speed information is acquired.

[0070] Furthermore, the initial speed information does not have to be set for each type of sheet SH1. In this case, when the speed information is acquired by the acquisition processing unit 42 and the setting condition is satisfied, the setting processing unit 43 may set the average value of the speed information stored in the second storage area of ​​the storage unit 6 or the speed information most recently stored in the second storage area as the initial speed information.

[0071] The determination processing unit 44 determines whether or not the maintenance timing for the sheet supply unit 28 has arrived based on the result of acquisition by the acquisition processing unit 42.

[0072] Specifically, the determination processing unit 44 determines whether or not the timing for maintenance of the sheet supply unit 28 has arrived based on the speed information acquired after the initial speed information is set and the initial speed information.

[0073] More specifically, the judgment processing unit 44 determines whether the maintenance timing for the sheet supply unit 28 has arrived based on the initial speed information corresponding to the type of sheet SH1 that was transported when the speed information was acquired by the acquisition processing unit 42, among the initial speed information corresponding to each type of sheet SH1.

[0074] For example, when the speed information is acquired by the acquisition processing unit 42, the judgment processing unit 44 determines that the time for maintenance of the sheet supply unit 28 has arrived if the difference between the acquired speed information and the initial speed information corresponding to the type of sheet SH1 transported at the time the speed information was acquired exceeds a predetermined first threshold value.

[0075] When the determination processing unit 44 determines that the maintenance timing for the sheet supply unit 28 has arrived, the notification processing unit 45 notifies the user of this fact.

[0076] For example, when the determination processing unit 44 determines that the maintenance timing for the sheet supply unit 28 has arrived, the notification processing unit 45 causes the operation display unit 5 to display a first notification screen including a message to that effect.

[0077] [Reset process] An example of the procedure of the reset process executed by the control unit 7 in the image forming apparatus 100 will be described below with reference to Fig. 5. Here, steps S11, S12, etc. represent the numbers of the process procedures (steps) executed by the control unit 7.

[0078] <Step S11> First, in step S11, the control unit 7 determines whether or not the sheet cassette 21 has been pulled out from the housing 100A.

[0079] Specifically, when the drawer sensor 26 outputs a detection signal indicating that the sheet cassette 21 has been drawn out, the control unit 7 determines that the sheet cassette 21 has been drawn out from the housing 100A.

[0080] Here, when the control unit 7 determines that the sheet feed cassette 21 has been pulled out from the housing 100A (Yes in S11), it shifts the process to step S12. On the other hand, when the sheet feed cassette 21 has not been pulled out from the housing 100A (No in S11), the control unit 7 waits in step S11 for the sheet feed cassette 21 to be pulled out from the housing 100A.

[0081] When the sheet cassette 21 is pulled out from the housing 100A, the engagement between the rotary shaft 32A and the joint portion is released, and the lift plate 31 descends under its own weight.

[0082] <Step S12> In step S12, the control unit 7 sets a predetermined measurement flag to OFF.

[0083] Specifically, in the image forming apparatus 100, a first storage area used to set the measurement flag is provided in advance in the storage unit 6. A value of "0" or "1" is stored in the first storage area. The control unit 7 sets the measurement flag to off by storing the value of "0" in the first storage area.

[0084] [1st Paper Feed Processing] Next, an example of the procedure of the first paper feed process executed by the control unit 7 in the image forming apparatus 100 will be described with reference to Fig. 6. The first paper feed process is executed when the timing for executing the image forming process arrives.

[0085] <Step S21> First, in step S21, the control unit 7 determines whether or not the specific timing has arrived.

[0086] Specifically, the control unit 7 determines that the specific timing has arrived when the measurement flag is set to OFF.

[0087] Here, if the control unit 7 determines that the specific timing has arrived (Yes in S21), it shifts the process to step S22. On the other hand, if the specific timing has not arrived (No in S21), it shifts the process to step S28.

[0088] <Step S22> In step S22, the control unit 7 executes a speed information acquisition process described below.

[0089] [Speed ​​information acquisition process] Here, an example of the procedure of the speed information acquisition process executed in step S22 of the first paper feed process will be described with reference to FIG.

[0090] <Step S41> First, in step S41, the control unit 7 uses the lift plate 31 to displace the sheet stack SB1 placed in the sheet cassette 21 to a position where the sheet stack SB1 comes into contact with the pickup roller 22. The process of step S41 is executed by the displacement processing unit 41 of the control unit 7.

[0091] <Step S42> In step S42, the control unit 7 causes the sheet supply unit 28 to start supplying the sheet SH1.

[0092] An image based on image data is formed by the image forming unit 3 on the sheet SH1 fed in the process of step S42.

[0093] <Step S43> In step S43, the control unit 7 measures the elapsed time from when the sheet supply unit 28 starts supplying the sheet SH1 to when the sheet sensor 25 detects the sheet SH1.

[0094] Here, the sheet SH1 to be fed in the processing of step S43 is the sheet SH1 that is first transported after the sheet feed cassette 21 is pulled out from the housing 100A and the sheet stack SB1 is set in the sheet feed cassette 21. In other words, the leading edge of the sheet SH1 to be fed in the processing of step S43 is not positioned downstream of the reference position P1 (see FIG. 4) in the sheet transport direction D5. Therefore, when the second or subsequent sheet SH1 is supplied after the sheet stack SB1 is lifted by the lift plate 31, the acquisition processing unit 42 can more accurately calculate the transport speed of the sheet SH1 by the sheet supply unit 28 compared to a configuration in which the acquisition processing unit 42 measures the elapsed time from when the sheet supply unit 28 starts to supply the sheet SH1 to when the sheet sensor 25 detects the sheet SH1.

[0095] <Step S44> In step S44, the control unit 7 acquires the speed information. The process of step S44 is an example of an acquisition step of the present invention, and is executed by the acquisition processing unit 42 of the control unit 7.

[0096] Specifically, the control unit 7 calculates the conveying speed of the sheet SH1 by the sheet supply unit 28 based on the measurement result obtained by the process of step S43 and the specific conveying distance.

[0097] <Step S45> In step S45, the control unit 7 records the speed information acquired by the process in step S44.

[0098] Specifically, the control unit 7 stores the speed information acquired by the processing of step S44 in the second memory area of ​​the memory unit 6 in association with the date and time when the speed information was acquired and the type of sheet SH1 that was transported when the speed information was acquired.

[0099] This concludes the description of the speed information acquisition process, and the description of the first paper feed process will now be resumed.

[0100] <Step S23> In step S23, the control unit 7 determines whether or not the set conditions are met.

[0101] Specifically, the control unit 7 determines that the set condition is satisfied when the cumulative number of times the sheet SH1 has been supplied by the sheet supply unit 28 is less than the reference number of times.

[0102] Here, if the control unit 7 determines that the set condition is satisfied (Yes in S23), the control unit 7 shifts the process to step S24. On the other hand, if the set condition is not satisfied (No in S23), the control unit 7 shifts the process to step S25.

[0103] <Step S24> In step S24, the control unit 7 sets the initial speed information. The process of step S24 is executed by the setting processing unit 43 of the control unit 7.

[0104] Specifically, the control unit 7 sets the average value of the speed information stored in the second memory area of ​​the memory unit 6, which is common to the speed information last stored for the type of associated sheet SH1, as the initial speed information corresponding to the type of sheet SH1.

[0105] <Step S25> In step S25, the control unit 7 determines whether or not it is time to perform maintenance on the sheet supply unit 28. The process of step S25 is executed by the determination processing unit 44 of the control unit 7.

[0106] Specifically, the control unit 7 determines that the time for maintenance of the sheet supply unit 28 has arrived when the difference between the most recently stored speed information among the speed information stored in the second memory area of ​​the memory unit 6 and the initial speed information corresponding to the type of sheet SH1 transported when the speed information was obtained exceeds the first threshold value.

[0107] In addition, if the initial speed information corresponding to the type of sheet SH1 transported when the last speed information was obtained has not been set, the control unit 7 can determine whether the maintenance timing for the sheet supply unit 28 has arrived by using the initial value corresponding to the type of sheet SH1 transported when the last speed information was obtained, from among the initial values ​​previously determined for each type of sheet SH1.

[0108] Here, when the control unit 7 determines that the maintenance timing for the sheet supply unit 28 has arrived (Yes in S25), the control unit 7 shifts the process to step S26. On the other hand, when the maintenance timing for the sheet supply unit 28 has not arrived (No in S25), the control unit 7 shifts the process to step S27.

[0109] <Step S26> In step S26, the control unit 7 causes the first notification screen to be displayed on the operation display unit 5. The processing of step S26 is executed by the notification processing unit 45 of the control unit 7.

[0110] This allows the user of the image forming apparatus 100 to recognize that it is time to perform maintenance on the sheet supply unit 28. Note that the control unit 7 may stop the conveyance of the sheet SH1 until an operation from the user is received on the operation display unit 5.

[0111] <Step S27> In step S27, the control unit 7 sets the measurement flag to ON.

[0112] Specifically, the control unit 7 sets the measurement flag to ON by storing the value “1” in the first storage area, which omits the processes from step S22 to step S27 until the paper feed cassette 21 is pulled out from the housing 100A.

[0113] <Step S28> In step S28, the control section 7 determines whether or not the timing for feeding the sheet SH1 has arrived.

[0114] Specifically, if sheet SH1 has not been fed after the start of the first sheet feeding process, the control unit 7 determines that the sheet feeding timing has arrived at the start of the process of step S28. Also, if sheet SH1 has been fed after the start of the first sheet feeding process, the control unit 7 determines that the sheet feeding timing has arrived when a predetermined time has elapsed since the sheet sensor 25 detected the immediately preceding sheet SH1.

[0115] Here, when the control unit 7 determines that the paper feed timing has arrived (Yes in S28), it shifts the process to step S29. On the other hand, when the paper feed timing has not arrived (No in S28), the control unit 7 waits for the arrival of the paper feed timing in step S28.

[0116] <Step S29> In step S29, the control unit 7 causes the sheet supply unit 28 to start supplying the sheet SH1.

[0117] An image based on image data is formed by the image forming unit 3 on the sheet SH1 fed in the process of step S29.

[0118] <Step S30> In step S30, the control section 7 determines whether or not feeding of the sheet SH1 has been completed.

[0119] Specifically, the control unit 7 determines that feeding of the sheets SH1 is completed when all of the sheets SH1 on which images are to be formed in the image forming process have been fed.

[0120] Here, when the control unit 7 determines that the feeding of the sheet SH1 has been completed (Yes in S30), it ends the first feeding process. On the other hand, when the feeding of the sheet SH1 has not been completed (No in S30), the control unit 7 shifts the process to step S28.

[0121] In this way, in the image forming apparatus 100, the speed information is acquired only when the sheet stack SB1 is lifted by the lift plate 31. This makes it possible to suppress a decrease in the accuracy of acquiring the conveying speed of the sheet SH1, compared to a configuration in which the timing of acquiring the speed information is not limited.

[0122] Furthermore, the image forming apparatus 100 uses the initial speed information set for each type of sheet SH1 to determine whether or not the maintenance timing for the sheet supply unit 28 has arrived. This makes it possible to more accurately detect the arrival of the maintenance timing for the sheet supply unit 28, compared to a configuration in which the initial speed information common to a plurality of types of sheet SH1 is used.

[0123] The lift plate 31 may be configured to descend each time the image forming process is completed. In this case, if the sheet SH1 fed out from the sheet stack SB1 when the lift plate 31 descends returns to the reference position P1 by its own weight or by the reverse rotation of the pickup roller 22 and the paper feed roller 23, the specific timing may be the timing of execution of the image forming process.

[0124] Furthermore, the lifting portion of the present invention is not limited to a flat plate-shaped member, but may be any member having a support surface that supports the bottom surface of the sheet stack SB1. Furthermore, the conveying member of the present invention is not limited to a roller-shaped member, but may be a belt-shaped member.

[0125] The present invention may also be applied to an inkjet image forming apparatus.

[0126] The present invention may also be applied to the ADF1.

[0127] In the image forming apparatus 100, the sheet bundle SB1 placed on the lift plate 31 may be improperly set. For example, in the image forming apparatus 100, the sheet bundle SB1 placed on the lift plate 31 may not be aligned by the end cursor 33 and the pair of side cursors 34 used to align the sheet bundle SB1. If the sheet bundle SB1 placed on the lift plate 31 is improperly set, problems such as paper jams may occur. However, conventionally, there has been no technology for determining whether the sheet bundle SB1 placed on the lift plate 31 is improperly set.

[0128] In contrast to this, in the image forming apparatus 200 according to the second embodiment of the present invention, as will be described below, it is possible to determine whether or not the sheet stack SB1 placed on the lift plate 31 is in the improper setting state.

[0129] [Second embodiment] The configuration of an image forming apparatus 200 according to the second embodiment of the present invention will be described below with reference to FIG.

[0130] Image forming apparatus 200 has the same configuration as image forming apparatus 100, except for the difference in the configuration of control unit 7. Specifically, as shown in Figures 3 and 8, control unit 7 of image forming apparatus 200 has a determination processing unit 51 and a notification processing unit 52 instead of setting processing unit 43, determination processing unit 44, and notification processing unit 45. Only the parts of the configuration of image forming apparatus 200 that are different from image forming apparatus 100 will be described below.

[0131] The determination processing unit 51 determines whether or not the sheet bundle SB1 is in the improper setting state based on the speed information acquired by the acquisition processing unit .

[0132] For example, the determination processing unit 51 determines whether the sheet bundle SB1 is in the improper setting state based on a plurality of pieces of speed information that are successively acquired, including the speed information that is last acquired.

[0133] In addition, the judgment processing unit 51 judges whether the sheet stack SB1 is in the improperly set state based on multiple pieces of speed information acquired by the acquisition processing unit 42, which have the same type of sheet SH1 transported at the time the speed information was acquired.

[0134] For example, when the speed information is stored in the second storage area of ​​the storage unit 6, the determination processing unit 51 identifies, from among the multiple speed information stored in the second storage area other than the most recently stored speed information, multiple speed information pieces whose associated sheet SH1 type is the same as the most recently stored speed information. The determination processing unit 51 then extracts a specific number of speed information pieces from the identified multiple speed information pieces in order of most recent storage timing. The determination processing unit 51 then determines that the sheet bundle SB1 is in the improperly set state if the difference between the average value of the specific number of extracted speed information pieces and the speed information last stored in the second storage area exceeds a predetermined second threshold. For example, the specific number is three. The determination processing unit 51 may also determine that the sheet bundle SB1 is in the improperly set state if the difference between the average value of all of the identified multiple speed information pieces and the speed information last stored in the second storage area exceeds the second threshold.

[0135] For example, if the sheet bundle SB1 is lifted by the lift plate 31 without being tightly sandwiched between the wall surface 21A (see FIG. 14) of the sheet cassette 21 and the end cursor 33, the sheet bundle SB1 moves toward the end cursor 33 due to its own weight. As a result, as shown in FIG. 14, the sheet supply position of the sheets SH1 by the sheet supply unit 28 moves upstream in the sheet conveying direction D5 from the reference position P1 (see FIG. 14). In other words, the speed information (conveying speed) acquired by the acquisition processing unit 42 decreases. By setting the second threshold so that this decrease can be detected, it is possible to detect misalignment of the sheet bundle SB1, that is, the improper setting state.

[0136] Furthermore, if the sheet bundle SB1 is not tightly sandwiched between the pair of side cursors 34, the sheet bundle SB1 may become tilted with respect to the sheet conveying direction D5, as shown in FIG. 15. In this case, the sheets SH1 conveyed by the sheet supply unit 28 are skewed, and the conveying load increases. In other words, the speed information (conveying speed) acquired by the acquisition processing unit 42 decreases. By setting the second threshold value so that this decrease can be detected, it is possible to detect misalignment of the sheet bundle SB1, i.e., the improper setting state.

[0137] Furthermore, if the sheet bundle SB1 lifted by the lift plate 31 is not loosened, the frictional force between the sheets SH1 increases, making the pickup roller 22 more likely to slip. In other words, the speed information (conveying speed) acquired by the acquisition processing unit 42 decreases. By setting the second threshold value so that this decrease can be detected, it is possible to detect a state in which the sheet bundle SB1 is not loosened, i.e., the improper setting state.

[0138] When the determination processing section 51 determines that the sheet bundle SB1 is in the improper setting state, the notification processing section 52 notifies the user of this fact.

[0139] For example, when the determination processing unit 51 determines that the sheet bundle SB1 is in the improperly set state, the notification processing unit 52 displays a second notification screen including a message indicating that the sheet bundle SB1 is in the improperly set state on the operation display unit 5. For example, the second notification screen includes a message indicating that the sheet bundle SB1 may not be aligned or loosened.

[0140] [Second Paper Feed Processing] Next, an example of the procedure of the second paper feed process executed by the control unit 7 in the image forming apparatus 200 will be described with reference to FIG.

[0141] 6 and 9, the second paper feed process is the same as the first paper feed process except that steps S51 to S52 are executed instead of steps S23 to S26. Only the parts of the second paper feed process that are different from the first paper feed process will be described below.

[0142] <Step S51> In step S51, the control section 7 determines whether the sheet bundle SB1 is in the improper setting state. The process of step S51 is an example of a determination step of the present invention, and is executed by the determination processing section 51 of the control section 7.

[0143] Specifically, the control unit 7 identifies a plurality of pieces of speed information stored in the second storage area of ​​the storage unit 6, other than the speed information last stored in the second storage area, that have the same type of associated sheet SH1 as the last stored speed information. The control unit 7 then extracts a predetermined number of pieces of speed information from the identified plurality of pieces of speed information in order of most recent storage timing. The determination processing unit 51 then determines that the sheet bundle SB1 is in the improper setting state when the difference between the average value of the extracted plurality of pieces of speed information and the speed information last stored in the second storage area exceeds the second threshold.

[0144] Here, if the control unit 7 determines that the sheet bundle SB1 is in the improper setting state (Yes in S51), the control unit 7 shifts the process to step S52. On the other hand, if the sheet bundle SB1 is not in the improper setting state (No in S51), the control unit 7 shifts the process to step S27.

[0145] <Step S52> In step S52, the control unit 7 causes the second notification screen to be displayed on the operation display unit 5. The process of step S52 is executed by the notification processing unit 52 of the control unit 7.

[0146] This allows the user of the image forming apparatus 200 to recognize that the sheet stack SB1 is in the improper setting state. Note that the control unit 7 may stop the conveyance of the sheets SH1 until a user operation is received on the operation display unit 5.

[0147] In this way, the image forming apparatus 200 can determine whether the sheet bundle SB1 placed on the lift plate 31 is in the improper setting state based on the speed information acquired by the acquisition processing unit .

[0148] In the image forming apparatus 100, the pickup roller 22 may deteriorate, reducing the amount of transport of the top sheet SH1 of the sheet stack SB1 by the pickup roller 22. However, there has conventionally been no technology for acquiring the amount of transport of the top sheet SH1 of the sheet stack SB1 by the pickup roller 22.

[0149] In contrast to this, in the image forming apparatus 300 according to the third embodiment of the present invention, it is possible to obtain the transport amount of the uppermost sheet SH1 of the sheet stack SB1 by the pickup roller 22, as will be described below.

[0150] [Third embodiment] The configuration of an image forming apparatus 300 according to the third embodiment of the present invention will be described below with reference to FIGS.

[0151] Image forming apparatus 300 has the same configuration as image forming apparatus 100, except for the configurations of sheet feeding unit 4 and control unit 7. Specifically, as shown in FIGS. 4 and 11, sheet feeding unit 4 of image forming apparatus 300 includes biasing unit 29. Also, as shown in FIGS. 3 and 10, control unit 7 of image forming apparatus 300 includes first determination processing unit 61, first acquisition processing unit 62, measurement processing unit 63, second acquisition processing unit 64, setting processing unit 65, adjustment processing unit 66, second determination processing unit 67, change processing unit 68, and notification processing unit 69, instead of acquisition processing unit 42, setting processing unit 43, determination processing unit 44, and notification processing unit 45. Only the parts of the configuration of image forming apparatus 300 that are different from image forming apparatus 100 will be described below.

[0152] The biasing unit 29 biases the pickup roller 22 toward the sheet stack SB1. The biasing unit 29 includes a coil spring that biases a holder that rotatably supports the pickup roller 22 downward, and a cam that is disposed opposite the holder across the coil spring and changes the biasing force of the coil spring.

[0153] When the sheet stack SB1 is lifted by the lift plate 31, the first judgment processing unit 61 determines whether the execution conditions for a measurement process are met, which measures the elapsed time from when the sheet supply unit 28 starts supplying the sheet SH1 to when the sheet sensor 25 detects the sheet SH1 after rotating the pickup roller 22 a predetermined reference amount.

[0154] For example, the execution condition may be that the number of consecutive executions of the process by the first acquisition processing unit 62 has reached a predetermined specific number. The number of consecutive executions of the process by the first acquisition processing unit 62 is counted by the control unit 7. The number of consecutive executions of the process by the first acquisition processing unit 62 is reset when the process by the measurement processing unit 63 has been executed. The execution condition may be that the cumulative number of times the paper feed cassette 21 has been attached and detached has reached an integer multiple of a predetermined value. The execution condition may be that the cumulative number of sheets SH1 supplied by the sheet supply unit 28 has reached an integer multiple of a predetermined value.

[0155] For example, when the lifting of the sheet stack SB1 by the lift plate 31 is the first lifting after the sheet cassette 21 is attached to the housing 100A, the first determination processing unit 61 determines whether the execution condition is met.

[0156] For example, every time the lift plate 31 lifts the sheet stack SB1, the first determination processing unit 61 determines whether the execution condition is met.

[0157] When the first determination processing unit 61 determines that the execution condition is not satisfied, the first acquisition processing unit 62 uses the sheet sensor 25 to acquire the speed information regarding the conveying speed of the sheet SH1 by the sheet supply unit .

[0158] The first acquisition processing unit 62 acquires the speed information in the same manner as the acquisition processing unit 42 .

[0159] The measurement processing unit 63 executes the measurement process when the first determination processing unit 61 determines that the execution condition is satisfied.

[0160] For example, the measurement processing unit 63 executes the measurement process when the first sheet SH1 is supplied after the sheet stack SB1 is lifted by the lift plate 31.

[0161] The measurement processing unit 63 may perform the measurement process when the second or subsequent sheet SH1 is supplied after the sheet stack SB1 is lifted by the lift plate 31.

[0162] The second acquisition processing unit 64 acquires the transport amount of the sheet SH1 when the pickup roller 22 is rotated by the reference amount, based on the acquisition result by the first acquisition processing unit 62 and the measurement result by the measurement process.

[0163] For example, when the measurement processing unit 63 measures the elapsed time, the second acquisition processing unit 64 acquires the speed information stored most recently among the speed information stored in the second storage area of ​​the storage unit 6. Then, the second acquisition processing unit 64 calculates the transport amount of the sheet SH1 when the pickup roller 22 is rotated by the reference amount by subtracting the multiplication result of the acquired speed information (transport speed) and the elapsed time measured by the measurement processing unit 63 from the specific transport distance. Note that the second acquisition processing unit 64 may acquire the transport amount of the sheet SH1 using the speed information stored most recently among the speed information corresponding to the type of sheet SH1 transported when the measurement processing unit 63 measured the elapsed time, which is stored in the second storage area of ​​the storage unit 6.

[0164] For example, the second acquisition processing unit 64 associates the acquired transport amount of the sheet SH1 with the date and time when the transport amount was acquired, and stores the associated transport amount in a predetermined third storage area of ​​the storage unit 6. Note that the second acquisition processing unit 64 may also store the acquired transport amount of the sheet SH1 in the third storage area in association with the type of the sheet SH1 that was transported when the transport amount was acquired.

[0165] The setting processing unit 65 sets the initial transport amount based on the result of acquisition by the second acquisition processing unit 64.

[0166] For example, when the conveyance amount of sheet SH1 is acquired by the second acquisition processing unit 64 and the setting conditions are satisfied, the setting processing unit 65 sets the average value of the conveyance amount of sheet SH1 stored in the third memory area of ​​the memory unit 6 as the initial conveyance amount.

[0167] The setting processing unit 65 may set the initial transport amount for each type of sheet SH1.

[0168] The adjustment processing unit 66 adjusts the biasing force of the biasing unit 29 based on the result of acquisition by the second acquisition processing unit 64.

[0169] For example, when the difference between the conveyance amount of the sheet SH1 acquired by the second acquisition processing unit 64 and the initial conveyance amount exceeds a predetermined amount, the adjustment processing unit 66 adjusts the urging force of the urging unit 29 so that the urging force of the urging unit 29 becomes stronger.

[0170] For example, the adjustment processing unit 66 adjusts the biasing force of the biasing unit 29 by rotating the cam.

[0171] The second determination processing unit 67 determines, based on the result acquired by the second acquisition processing unit 64, whether or not the timing for maintenance of the pickup roller 22 has arrived.

[0172] For example, the second judgment processing unit 67 determines whether the maintenance timing for the pickup roller 22 has arrived based on the conveyance amount of the sheet SH1 when the pickup roller 22 is rotated by the reference amount obtained after the initial conveyance amount is set and the initial conveyance amount.

[0173] For example, when the conveyance amount of sheet SH1 is acquired by the second acquisition processing unit 64, the second judgment processing unit 67 determines that the time for maintenance of the pickup roller 22 has arrived if the difference between the acquired conveyance amount of sheet SH1 and the initial conveyance amount exceeds a predetermined third threshold value.

[0174] The change processing unit 68 changes the execution condition so that the frequency with which the execution condition is satisfied increases as the difference between the initial carry amount and the carry amount of sheet SH1 acquired by the second acquisition processing unit 64 increases. For example, the change processing unit 68 changes the execution condition so that the frequency with which the execution condition is satisfied increases each time the difference between the initial carry amount and the carry amount of sheet SH1 acquired by the second acquisition processing unit 64 reaches an integer multiple of a predetermined reference carry amount. The reference carry amount is a value smaller than the third threshold value.

[0175] For example, the change processing unit 68 decrements the specific number of times each time the difference between the initial transport amount and the transport amount of the sheet SH1 acquired by the second acquisition processing unit 64 reaches an integer multiple of the reference transport amount.

[0176] The change processing unit 68 may change the execution condition so that the frequency with which the execution condition is satisfied increases as the cumulative number of sheets SH1 supplied by the sheet supply unit 28 increases. For example, the change processing unit 68 may change the execution condition so that the frequency with which the execution condition is satisfied increases each time the cumulative number of sheets SH1 supplied by the sheet supply unit 28 reaches an integral multiple of a predetermined reference number.

[0177] When the second determination processing unit 67 determines that the time for maintenance of the pickup roller 22 has arrived, the notification processing unit 69 notifies the user of this fact.

[0178] For example, when the second determination processing unit 67 determines that the time for maintenance of the pickup roller 22 has arrived, the notification processing unit 69 causes the operation display unit 5 to display a third notification screen including a message to that effect.

[0179] [Third Paper Feed Processing] Next, an example of the procedure of the third paper feed process executed by the control unit 7 in the image forming apparatus 300 will be described with reference to FIG.

[0180] 6 and 12, the third paper feed process is the same as the first paper feed process except that steps S61 to S66 are executed instead of steps S23 to S26, and the timing of execution of step S22 is different. Only the parts of the third paper feed process that are different from the first paper feed process will be described below.

[0181] <Step S61> In step S61, the control unit 7 determines whether the execution condition is satisfied. The process of step S61 is an example of a first determination step of the present invention, and is executed by the first determination processing unit 61 of the control unit 7.

[0182] Specifically, the control unit 7 determines that the execution condition is met when the number of consecutive executions of the process of step S22 reaches the specific number of times.

[0183] Here, if the control unit 7 determines that the execution condition is satisfied (Yes in S61), the control unit 7 shifts the process to step S62. On the other hand, if the execution condition is not satisfied (No in S61), the control unit 7 shifts the process to step S22.

[0184] <Step S62> In step S62, the control unit 7 executes the transport amount acquisition process described below.

[0185] [Transport amount acquisition process] Here, an example of the procedure of the transport amount acquisition process executed in step S62 of the third paper feed process will be described with reference to FIG.

[0186] <Step S71> First, in step S71, the control unit 7 uses the lift plate 31 to displace the sheet stack SB1 placed in the sheet cassette 21 to a position where the sheet stack SB1 comes into contact with the pickup roller 22. The process of step S71 is executed by the displacement processing unit 41 of the control unit 7.

[0187] <Step S72> In step S72, the control unit 7 rotates the pick-up roller 22 by the reference amount.

[0188] <Step S73> In step S73, the control section 7 causes the sheet supply section 28 to start supplying the sheet SH1.

[0189] An image based on image data is formed by the image forming unit 3 on the sheet SH1 fed in the process of step S73.

[0190] <Step S74> In step S74, the control unit 7 measures the elapsed time from when the sheet supply unit 28 starts supplying the sheet SH1 to when the sheet sensor 25 detects the sheet SH1. The processing of step S74 is an example of a measurement step of the present invention, and is executed by the measurement processing unit 63 of the control unit 7.

[0191] <Step S75> In step S75, the control unit 7 acquires the transport amount of the sheet SH1 when the pickup roller 22 is rotated by the reference amount. The process of step S75 is an example of a second acquisition step of the present invention, and is executed by the second acquisition processing unit 64 of the control unit 7.

[0192] Specifically, the control unit 7 acquires the speed information that was stored most recently from the speed information stored in the second storage area of ​​the storage unit 6. Then, the control unit 7 calculates the transport amount of the sheet SH1 when the pickup roller 22 is rotated by the reference amount by subtracting the multiplication result of the acquired speed information (transport speed) and the elapsed time measured in the processing of step S74 from the specific transport distance.

[0193] <Step S76> In step S76, the control unit 7 records the conveyance amount of the sheet SH1 acquired in the process of step S75.

[0194] Specifically, the control unit 7 stores the transport amount of the sheet SH1 acquired in the process of step S75 in the third storage area of ​​the storage unit 6 in association with the date and time when the transport amount was acquired.

[0195] <Step S77> In step S77, the control unit 7 adjusts the biasing force of the biasing unit 29 based on the conveyance amount of the sheet SH1 acquired in the process of step S75. The process of step S77 is executed by the adjustment processing unit 66 of the control unit 7.

[0196] Specifically, when the difference between the transport amount of sheet SH1 acquired by the process of step S75 and the initial transport amount exceeds a predetermined amount, the control unit 7 adjusts the urging force of the urging unit 29 so that the urging force of the urging unit 29 becomes stronger. This makes it possible to prevent a decrease in the transport amount of sheet SH1 by the pickup roller 22 due to deterioration of the pickup roller 22.

[0197] <Step S78> In step S78, the control unit 7 determines whether or not the change condition for the execution condition is satisfied.

[0198] Specifically, the control unit 7 determines that the change condition is met when the difference between the initial transport amount and the transport amount of the sheet SH1 acquired by the process of step S75 reaches an integral multiple of the reference transport amount.

[0199] Here, if the control unit 7 determines that the change condition is satisfied (Yes in S78), the control unit 7 shifts the process to step S79. On the other hand, if the change condition is not satisfied (No in S78), the control unit 7 ends the conveyance amount acquisition process.

[0200] <Step S79> In step S79, the control unit 7 changes the execution conditions. The process of step S79 is executed by the change processing unit 68 of the control unit 7.

[0201] Specifically, the control unit 7 decrements the specific number of times, so that the more the pickup roller 22 deteriorates, the more frequently the second determination processing unit 67 makes a determination.

[0202] This concludes the description of the transport amount acquisition process, and the description of the third paper feed process will now be resumed.

[0203] <Step S63> In step S63, the control unit 7 determines whether the set conditions are met.

[0204] Specifically, the control unit 7 determines that the set condition is satisfied when the cumulative number of times the sheet SH1 has been supplied by the sheet supply unit 28 is less than the reference number of times.

[0205] Here, if the control unit 7 determines that the set condition is satisfied (Yes in S63), the control unit 7 shifts the process to step S64. On the other hand, if the set condition is not satisfied (No in S63), the control unit 7 shifts the process to step S65.

[0206] <Step S64> In step S64, the control unit 7 sets the initial transport amount. The process of step S64 is executed by the setting processing unit 65 of the control unit 7.

[0207] Specifically, the control unit 7 sets the average value of the transport amounts of the sheet SH1 stored in the third storage area of ​​the storage unit 6 as the initial transport amount.

[0208] <Step S65> In step S65, the control unit 7 determines whether or not it is time to perform maintenance on the pickup roller 22. The process of step S65 is executed by the second determination processing unit 67 of the control unit 7.

[0209] Specifically, the control unit 7 determines that the time for maintenance of the pickup roller 22 has arrived when the difference between the transport amount of the sheet SH1 last stored in the third memory area of ​​the memory unit 6 and the initial transport amount exceeds the third threshold value.

[0210] Here, if the control unit 7 determines that the maintenance timing for the pickup roller 22 has arrived (Yes in S65), it shifts the process to step S66. On the other hand, if the maintenance timing for the pickup roller 22 has not arrived (No in S65), the control unit 7 shifts the process to step S27.

[0211] <Step S66> In step S66, the control unit 7 causes the third notification screen to be displayed on the operation display unit 5. The processing of step S66 is executed by the notification processing unit 69 of the control unit 7.

[0212] This allows the user of image forming apparatus 300 to recognize that it is time to perform maintenance on pickup roller 22. Note that control unit 7 may stop the transport of sheet SH1 until a user operation is received on operation display unit 5.

[0213] In this way, the image forming apparatus 300 can acquire the transport amount of the topmost sheet SH1 of the sheet stack SB1 by the pickup roller 22 based on the speed information acquired by the first acquisition processing unit 62 and the elapsed time measured by the measurement processing unit 63.

[0214] The setting processing unit 65 may set the initial elapsed time in the same manner as the initial conveyance amount, based on the measurement result by the measurement processing unit 63. The second determination processing unit 67 may determine whether or not the maintenance timing for the pickup roller 22 has arrived, based on the elapsed time measured by the measurement processing unit 63 after the initial elapsed time is set and the initial elapsed time. In this case, the image forming apparatus 300 may not include the first determination processing unit 61, the first acquisition processing unit 62, the second acquisition processing unit 64, the adjustment processing unit 66, and the change processing unit 68.

[0215] [Notes on the Invention] The following is a summary of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0216] <Appendix 1> A sheet conveying device comprising: a lift section that lifts a sheet stack; a sheet supply section that includes a conveying member that rotates in contact with the upper surface of the sheet stack lifted by the lift section and supplies sheets that come into contact with the conveying member to a conveying path; a detection section that detects the sheets supplied by the sheet supply section in the conveying path; and an acquisition processing section that uses the detection section to acquire speed information regarding the conveying speed of the sheets by the sheet supply section only when the sheet stack is lifted by the lift section.

[0217] <Appendix 2> A sheet conveying device as described in Appendix 1, comprising a sheet storage section that is detachably provided on a housing of the sheet conveying device and stores the sheet stack, the lift section is provided in the sheet storage section, and the acquisition processing section acquires the speed information when the lifting of the sheet stack by the lift section is the first lifting after the sheet storage section is attached to the housing.

[0218] <Appendix 3> 3. The sheet conveying device according to claim 1, wherein the acquisition processing unit acquires the speed information when the first sheet is supplied after the sheet stack is lifted by the lift unit.

[0219] <Appendix 4> 4. The sheet conveying device according to any one of claims 1 to 3, further comprising a determination processing unit that determines whether or not a maintenance timing has arrived for the sheet supply unit based on the result of acquisition by the acquisition processing unit.

[0220] <Appendix 5> The sheet conveying device described in Appendix 4, wherein the acquisition processing unit acquires the speed information each time the sheet stack is lifted by the lift unit, the sheet conveying device includes a setting processing unit that sets initial speed information based on the acquisition result by the acquisition processing unit, and the judgment processing unit judges whether the maintenance timing has arrived based on the speed information acquired after the initial speed information is set and the initial speed information.

[0221] <Appendix 6> The sheet conveying device described in Appendix 5, wherein the setting processing unit sets the initial speed information for each type of sheet, and the judgment processing unit determines whether the maintenance timing has arrived based on the initial speed information corresponding to the type of sheet conveyed when the speed information was acquired by the acquisition processing unit, among the initial speed information corresponding to each type of sheet.

[0222] <Appendix 7> 7. The sheet conveying device according to any one of claims 4 to 6, further comprising a notification processing section that, when the determination processing section determines that the maintenance timing has arrived, issues a notification to that effect.

[0223] <Appendix 8> 8. An image forming apparatus comprising: the sheet conveying device according to any one of claims 1 to 7; and an image forming section that forms an image on the sheet conveyed by the sheet conveying device.

[0224] <Appendix 9> An acquisition method performed by a sheet conveying device comprising: a lift section that lifts a sheet stack; a sheet supply section that includes a conveying member that rotates in contact with the upper surface of the sheet stack lifted by the lift section and supplies the sheet that contacts the conveying member to a conveying path; and a detection section that detects the sheet supplied by the sheet supply section in the conveying path, the acquisition method including an acquisition step that uses the detection section to acquire speed information regarding the conveying speed of the sheet by the sheet supply section only when the sheet stack is lifted by the lift section. [Explanation of symbols]

[0225] 1 ADF 2 Image reading unit 3 Image forming unit 4 Paper feed section 5 Operation display section 6 Memory section 7 Control Unit 21 Paper cassette 22 Pickup roller 23 Paper feed roller 24 Separation roller 25 Sheet Sensor 26 Drawer Sensor 27 Transport path 28 Sheet supply unit 29. Actuation section 31 Lift Board 41 Displacement processing section 42 Acquisition processing unit 43 Setting processing section 44 Judgment processing unit 45 Notification processing section 51 Judgment processing unit 52 Notification processing section 61 First determination processing unit 62 First acquisition processing unit 63 Measurement processing section 64 Second acquisition processing unit 65 Setting processing section 66 Adjustment processing section 67 Second determination processing unit 68 Change Processing Section 69 Notification processing section 100 Image forming device 200 Image forming device 300 Image forming device

Claims

1. a lift unit that lifts the sheet stack; a sheet supply unit including a conveying member that rotates while contacting an upper surface of the sheet stack lifted by the lift unit, and that supplies the sheet that contacts the conveying member to a conveyance path; a detection unit that detects the sheet fed by the sheet feeding unit in the conveying path; an acquisition processing unit that acquires speed information regarding a conveying speed of the sheets by the sheet supply unit using the detection unit only when the sheet stack is lifted by the lift unit; A sheet conveying device comprising:

2. a sheet storage section that is detachably provided on a housing of the sheet conveying device and that stores the sheet stack; The lift unit is provided in the sheet storage unit, the acquisition processing unit acquires the speed information when the lifting of the sheet stack by the lift unit is the first lifting of the sheet stack after the sheet storage unit is attached to the housing. The sheet transport device according to claim 1 .

3. the acquisition processing unit acquires the speed information when the first sheet is supplied after the sheet stack is lifted by the lift unit.

3. The sheet conveying device according to claim 1 or 2.

4. a determination processing unit that determines whether or not a maintenance timing has arrived for the sheet supply unit based on the result of acquisition by the acquisition processing unit; 3. The sheet conveying device according to claim 1 or 2.

5. the acquisition processing unit acquires the speed information each time the sheet stack is lifted by the lift unit, the sheet conveying device includes a setting processing unit that sets initial speed information based on the result of acquisition by the acquisition processing unit; the determination processing unit determines whether the maintenance timing has arrived based on the speed information acquired after the initial speed information is set and the initial speed information. The sheet transport device according to claim 4 .

6. the setting processing unit sets the initial speed information for each type of the sheet; the determination processing unit determines whether the maintenance timing has arrived based on the initial speed information corresponding to the type of the sheet that was conveyed when the speed information was acquired by the acquisition processing unit, among the initial speed information corresponding to each type of the sheet. The sheet transport device according to claim 5 .

7. a notification processing unit that notifies the user when it is determined by the determination processing unit that the maintenance timing has arrived; The sheet transport device according to claim 4 .

8. The sheet conveying device according to claim 1 or 2; an image forming unit that forms an image on the sheet conveyed by the sheet conveying device; An image forming apparatus comprising:

9. An acquisition method executed by a sheet conveying device including: a lift unit that lifts a sheet stack; a sheet supply unit that includes a conveying member that rotates in contact with an upper surface of the sheet stack lifted by the lift unit and supplies a sheet that contacts the conveying member to a conveying path; and a detection unit that detects the sheet that is supplied by the sheet supply unit in the conveying path, an acquiring step of acquiring speed information related to a conveying speed of the sheets by the sheet supply unit using the detection unit only when the sheet stack is lifted by the lift unit; How to get it.

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