Sheet conveying device, image forming apparatus, and acquisition method

Abstract

To provide a sheet conveying device, an image forming apparatus, and an acquisition method capable of acquiring a delivery amount of a sheet from a sheet bundle without providing a dedicated sensor.SOLUTION: The image forming apparatus 100 includes a first measurement processing portion 42 configured to measure an elapsed time from a start of sheet feeding to sheet detection by the sheet sensor 25 when the sheet bundle is lifted by the lift plate of the sheet feed cassette, a second measurement processing portion 43 configured to measure an elapsed time from the start of sheet feeding to the sheet detection by the sheet sensor 25 after the measurement by the first measurement processing portion 42, and an acquisition processing portion 44 configured to acquire an amount of the sheet fed from the sheet bundle based on a result of the measurement by the first measurement processing portion 42 and a result of the measurement by the second measurement processing portion 43.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 and a sheet supply 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.

[0003] In the sheet conveying device, the sheet below the sheet being conveyed by the conveying member may be pulled by the sheet being conveyed and fed out from the sheet stack. In response to this, a sheet conveying device equipped with an image sensor capable of detecting the amount of protrusion of the sheet from a separating nip portion is known as related technology (see Patent Document 1). By changing the position of the image sensor in this sheet conveying device, the image sensor can be used to obtain the amount of the sheet being fed out from the sheet stack. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-104663 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a configuration in which the image sensor is used to obtain the amount of the sheet fed out from the sheet stack, a dedicated sensor must be provided to obtain the amount of the sheet fed out from the sheet stack.

[0006] An object of the present invention is to provide a sheet conveying device, an image forming apparatus, and an acquisition method that can acquire the amount of sheets fed out from a sheet stack without providing a dedicated sensor. [Means for solving the problem]

[0007] According to one aspect of the present invention, a sheet transport device includes a lift unit, a sheet supply unit, a detection unit, a first measurement processing unit, a second measurement processing 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. When the sheet stack is lifted by the lift unit, the first measurement processing unit measures the elapsed time from when the sheet supply unit starts supplying the sheet to when the detection unit detects the sheet. After the measurement by the first measurement processing unit, the second measurement processing unit measures the elapsed time from when the sheet supply unit starts supplying the sheet to when the detection unit detects the sheet. The acquisition processing unit acquires the amount of the acquisition target sheet fed out of the sheet stack at the start of supply of the acquisition target sheet supplied at the time of measurement by the second measurement processing unit, based on the measurement results by the first measurement processing unit and the measurement results by the second measurement processing unit.

[0008] 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.

[0009] According to another aspect of the present invention, an acquisition method is performed by a sheet transport device including a lift unit that lifts a sheet stack, a sheet supply unit that 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, and a detection unit that detects the sheet supplied by the sheet supply unit in the transport path. The acquisition method includes a first measurement step, a second measurement step, and an acquisition step. In the first measurement step, when the sheet stack is lifted by the lift unit, the elapsed time from when the sheet supply unit starts supplying the sheet to when the detection unit detects the sheet is measured. In the second measurement step, after the measurement in the first measurement step, the elapsed time from when the sheet supply unit starts supplying the sheet to when the detection unit detects the sheet is measured. In the acquisition step, the amount of the target sheet fed from the sheet stack at the time of start of supply of the target sheet supplied at the time of measurement in the second measurement step is acquired based on the measurement results in the first measurement step and the second measurement step. [Effects of the Invention]

[0010] According to the present invention, it is possible to obtain the amount of sheets fed out from the sheet stack without providing a dedicated sensor. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the appearance of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the internal configuration of the image forming apparatus according to the 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 embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the configuration of a sheet supply unit of the image forming apparatus according to the 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 embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing an example of a paper feeding process executed by the image forming apparatus according to the embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing the configuration of a sheet supply unit of an image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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.

[0013] [Configuration of image forming apparatus 100] First, the configuration of an image forming apparatus 100 according to an 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.

[0014] 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.

[0015] 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.

[0016] 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 .

[0017] 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).

[0018] 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.

[0019] 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).

[0020] 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.

[0021] 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.

[0022] The storage unit 6 is a non-volatile storage device, such as a flash memory.

[0023] 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.

[0024] The paper feed unit 4 supplies the sheet SH1 (see FIG. 2) to the image forming unit 3.

[0025] 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.

[0026] 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.

[0027] 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 .

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 SH12 (see FIG. 7) (an example of an accompanying sheet of the present invention) accompanying sheet SH11 from sheet SH11 (see FIG. 7) conveyed by pickup roller 22.

[0040] 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.

[0041] When only one sheet SH1 is present in the separation unit 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. 7) are present in the separation unit 28A, the separation roller 24 is restricted from rotating in the rotation direction D8. For example, the sheet supply unit 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 threshold. When sheets SH11 and SH12 are present in the separation unit 28A, the rotation of the separation roller 24 in the rotation direction D8 is restricted, and 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] In response to this, a sheet conveying device equipped with an image sensor capable of detecting the amount of protrusion of sheet SH1 from separation section 28A is known as related technology. By changing the position of the image sensor in this sheet conveying device, it is possible to use the image sensor to obtain the amount of sheet SH1 being fed out from sheet stack SB1.

[0046] However, in a configuration in which the image sensor is used to obtain the amount of sheet SH1 fed out from the sheet bundle SB1, a dedicated sensor must be provided to obtain the amount of sheet SH1 fed out from the sheet bundle SB1.

[0047] In contrast to this, in the image forming apparatus 100 according to the embodiment of the present invention, as will be described below, it is possible to obtain the amount of feed of the sheet SH1 from the sheet stack SB1 without providing a dedicated sensor.

[0048] [Configuration of control unit 7] Next, the configuration of the control unit 7 will be described with reference to FIG.

[0049] 3, the control unit 7 includes a displacement processing unit 41, a first measurement processing unit 42, a second measurement processing unit 43, an acquisition processing unit 44, a determination processing unit 45, and a notification processing unit 46. 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.

[0050] 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 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] When the sheet stack SB1 is lifted by the lift plate 31, the first measurement 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.

[0056] For example, when the lifting of the sheet stack SB1 by the lift plate 31 is the first lifting after the paper feed cassette 21 is installed in the housing 100A, the first measurement 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.

[0057] For example, each time the lift plate 31 lifts the sheet stack SB1, the first measurement 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.

[0058] For example, when the first sheet SH1 is supplied after the sheet stack SB1 is lifted by the lift plate 31, the first measurement 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.

[0059] The first measurement processing unit 42 may measure 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 when the second or subsequent sheet SH1 is supplied after the sheet stack SB1 is lifted by the lift plate 31. In this case, when the difference between the measured elapsed time and the elapsed time based on a previously acquired average sheet feeding speed exceeds a predetermined value, the first measurement processing unit 42 may acquire the elapsed time based on the previously acquired average sheet feeding speed instead of the measured elapsed time.

[0060] After the measurement by the first measurement processing unit 42, the second measurement processing unit 43 measures the elapsed time from when the sheet supply unit 28 starts to supply the sheet SH1 until when the sheet sensor 25 detects the sheet SH1.

[0061] For example, after measurement by the first measurement processing unit 42, the second measurement processing unit 43 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 each time the sheet SH1 is supplied.

[0062] Based on the measurement results by the first measurement processing unit 42 and the measurement results by the second measurement processing unit 43, the acquisition processing unit 44 acquires the amount of the acquisition target sheet fed out from the sheet stack SB1 at the start of supply of the acquisition target sheet supplied at the time of measurement by the second measurement processing unit 43.

[0063] For example, the acquisition processing unit 44 acquires the amount of the acquisition target sheet fed out from the sheet bundle SB1 at the start of supply of the acquisition target sheet based on the immediately preceding measurement result by the first measurement processing unit 42. Furthermore, the acquisition processing unit 44 acquires the amount of the acquisition target sheet fed out from the sheet bundle SB1 at the start of supply of the acquisition target sheet every time elapsed time is measured by the second measurement processing unit 43. Note that the acquisition processing unit 44 may acquire the amount of the acquisition target sheet fed out from the sheet bundle SB1 at the start of supply of the acquisition target sheet based on the average value of the measurement results by the first measurement processing unit 42 a predetermined number of times immediately before.

[0064] For example, the acquisition processing unit 44 calculates the conveying speed of the sheet SH1 by the sheet supply unit 28 based on the measurement result by the first measurement processing unit 42 and a first conveying distance from the reference position P1 (see FIG. 4) to the detection position. The first conveying distance is the distance from the reference position P1 to the detection position on the conveying path of the sheet SH1. The first conveying distance may be stored in advance in the storage unit 6 or the ROM 12.

[0065] In addition, the acquisition processing unit 44 calculates the transport distance of the target sheet by the sheet supply unit 28 to the detection position based on the calculated transport speed of the sheet SH1 by the sheet supply unit 28 and the measurement results by the second measurement processing unit 43.

[0066] Then, the acquisition processing unit 44 acquires the difference between the first conveying distance and the calculated conveying distance of the target sheet as the amount of feed of the target sheet from the sheet stack SB1 at the start of supplying the target sheet (amount of movement from the reference position P1).

[0067] In addition, the acquisition processing unit 44 may calculate the ratio of the difference between the measurement result by the first measurement processing unit 42 and the measurement result by the second measurement processing unit 43 relative to the measurement result by the first measurement processing unit 42, and obtain the payout amount of the sheet to be acquired by multiplying the calculated ratio by the first conveying distance.

[0068] The determination processing unit 45 determines, based on the result of acquisition by the acquisition processing unit 44, whether or not the acquisition target sheet protrudes beyond the separation unit 28A.

[0069] For example, when the result of acquisition by the acquisition processing unit 44 exceeds a second transport distance from the reference position P1 (see FIG. 4) to the separation unit 28A, the determination processing unit 45 determines that the acquisition target sheet protrudes beyond the separation unit 28A. The second transport distance is the distance from the reference position P1 to the separation unit 28A on the transport path of the sheet SH1. The second transport distance may be stored in advance in the storage unit 6 or the ROM 12.

[0070] When it is determined that the acquisition target sheet protrudes beyond the separation unit 28A, the notification processor 46 issues a notification to that effect.

[0071] For example, when it is determined that the target sheet has protruded beyond the separation section 28A and a predetermined notification condition is satisfied, the notification processing section 46 notifies that the target sheet has protruded beyond the separation section 28A.

[0072] For example, the determination condition is that the frequency with which it is determined that the acquisition target sheet has protruded beyond the separation unit 28A exceeds a predetermined value. Note that the determination condition may also be that the amount of protrusion of the acquisition target sheet from the separation unit 28A exceeds a predetermined amount. Furthermore, when it is determined that the acquisition target sheet has protruded beyond the separation unit 28A, the notification processing unit 46 may unconditionally notify the fact that the acquisition target sheet has protruded beyond the separation unit 28A.

[0073] For example, when it is determined that the target sheet has protruded beyond the separation section 28A and the notification condition is satisfied, the notification processing section 46 causes the operation display section 5 to display a notification screen including a message indicating that the target sheet has protruded beyond the separation section 28A.

[0074] [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.

[0075] <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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] <Step S12> In step S12, the control unit 7 sets a predetermined measurement flag to OFF.

[0080] 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.

[0081] [Paper Feed Processing] Next, with reference to Fig. 6, an example of the procedure of the paper feed process executed by the control unit 7 in the image forming apparatus 100 and an acquisition method of the present invention will be described. The paper feed process is executed when the timing for executing the image forming process arrives.

[0082] <Step S21> First, in step S21, the control unit 7 determines whether or not the specific timing has arrived.

[0083] Specifically, the control unit 7 determines that the specific timing has arrived when the measurement flag is set to OFF.

[0084] Here, when 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, when the specific timing has not arrived (No in S21), the control unit 7 shifts the process to step S27.

[0085] <Step S22> In step S22, 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 S22 is executed by the displacement processing unit 41 of the control unit 7.

[0086] <Step S23> In step S23, the control section 7 causes the sheet supply section 28 to start supplying the sheet SH1.

[0087] An image based on image data is formed by the image forming unit 3 on the sheet SH1 fed in the process of step S23.

[0088] <Step S24> In step S24, 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 S24 is an example of a first measurement step of the present invention, and is executed by the first measurement processing unit 42 of the control unit 7.

[0089] Here, the sheet SH1 to be fed in the processing of step S23 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 S23 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 first measurement 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 first measurement 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.

[0090] <Step S25> In step S25, the control unit 7 records the elapsed time measured in the process of step S24.

[0091] Specifically, in the image forming apparatus 100, a second storage area used for recording the elapsed time measured by the processing of step S24 is provided in advance in the storage unit 6. For example, the control unit 7 records the elapsed time measured by the processing of step S24 by storing the elapsed time measured by the processing of step S24 in the second storage area in association with the execution time of the processing of step S24.

[0092] <Step S26> In step S26, the control unit 7 sets the measurement flag to ON.

[0093] 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 S26 until the paper feed cassette 21 is pulled out from the housing 100A.

[0094] <Step S27> In step S27, the control section 7 determines whether or not the timing for feeding the sheet SH1 has arrived.

[0095] Specifically, if sheet SH1 has not been fed after the start of the feeding process, the control unit 7 determines that the feeding timing has arrived at the start of the process of step S27. Also, if sheet SH1 has been fed after the start of the feeding process, the control unit 7 determines that the feeding timing has arrived when a predetermined time has elapsed since the sheet sensor 25 detected the previous sheet SH1.

[0096] Here, when the control unit 7 determines that the paper feed timing has arrived (Yes in S27), it shifts the process to step S28. On the other hand, when the paper feed timing has not arrived (No in S27), the control unit 7 waits for the arrival of the paper feed timing in step S27.

[0097] <Step S28> In step S28, the control section 7 causes the sheet supply section 28 to start supplying the sheet SH1.

[0098] An image based on image data is formed by the image forming unit 3 on the sheet SH1 fed in the process of step S28.

[0099] <Step S29> In step S29, 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 S29 is an example of a second measurement step of the present invention, and is executed by the second measurement processing unit 43 of the control unit 7.

[0100] <Step S30> In step S30, the control unit 7 acquires the payout amount of the target sheet SH1 (the target sheet) from the sheet bundle SB1 at the time of starting to supply the target sheet SH1, which was supplied at the time of measurement in the process of the immediately preceding step S29, based on the latest measurement result among the measurement results stored in the second storage area and the measurement result in the process of the immediately preceding step S29. The process of step S30 is an example of an acquisition step of the present invention, and is executed by the acquisition processing unit 44 of the control unit 7.

[0101] In addition, the control unit 7 may obtain the amount of feed of the sheet SH1 by using the average value of the measurement results stored in the second storage area that have been measured within a predetermined specific period up to the present time.

[0102] <Step S31> In step S31, the control unit 7 determines whether the target sheet protrudes beyond the separation unit 28A based on the result of the process in the immediately preceding step S30. The process in step S31 is executed by the determination processing unit 45 of the control unit 7.

[0103] Here, if the control unit 7 determines that the target sheet protrudes beyond the separation unit 28A (Yes in S31), the control unit 7 shifts the process to step S32. On the other hand, if the target sheet does not protrude beyond the separation unit 28A (No in S31), the control unit 7 shifts the process to step S34.

[0104] <Step S32> In step S32, the control unit 7 determines whether the notification condition is met.

[0105] Here, if the control unit 7 determines that the notification condition is satisfied (Yes in S32), the control unit 7 shifts the process to step S33. On the other hand, if the notification condition is not satisfied (No in S32), the control unit 7 shifts the process to step S34.

[0106] <Step S33> In step S33, the control unit 7 causes the notification screen to be displayed on the operation display unit 5. The process of step S33 is executed by the notification processing unit 46 of the control unit 7.

[0107] This makes it possible to make the user of image forming apparatus 100 aware of the deterioration in the functionality of separation unit 28A. Note that the notification screen may include a message indicating that maintenance of paper feed roller 23 and separation roller 24 is required.

[0108] <Step S34> In step S34, the control section 7 determines whether or not feeding of the sheet SH1 has been completed.

[0109] 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.

[0110] Here, when the control unit 7 determines that the feeding of the sheet SH1 has been completed (Yes in S34), it ends the feeding process. On the other hand, when the feeding of the sheet SH1 has not been completed (No in S34), the control unit 7 shifts the process to step S27.

[0111] In this way, in the image forming apparatus 100, when the sheet bundle SB1 is lifted by the lift plate 31, the first measurement 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. After the measurement by the first measurement processing unit 42, the second measurement processing unit 43 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. Then, based on the measurement results by the first measurement processing unit 42 and the measurement results by the second measurement processing unit 43, the payout amount of the acquisition target sheet from the sheet bundle SB1 at the time when the supply of the acquisition target sheet started at the time of measurement by the second measurement processing unit 43 is obtained. This makes it possible to obtain the payout amount of the sheet SH1 from the sheet bundle SB1 without providing a dedicated sensor.

[0112] Furthermore, in the image forming apparatus 100, each time the lift plate 31 lifts the sheet bundle SB1, the first measurement processor 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. Then, based on the immediately preceding measurement result by the first measurement processor 42, the payout amount of the target sheet from the sheet bundle SB1 is acquired. This allows the amount of sheet SH1 paid out from the sheet bundle SB1 to be acquired based on the conveyance speed after the change, even if the conveyance speed of the sheet SH1 by the sheet supply unit 28 changes due to a change in either or both of the size and type of the sheet SH1. Furthermore, even if the conveyance speed of the sheet SH1 by the sheet supply unit 28 decreases due to deterioration over time, the amount of sheet SH1 paid out from the sheet bundle SB1 can be acquired based on the conveyance speed after the decrease.

[0113] The second storage area may store elapsed times associated with combinations of the type and size of the sheet SH1. In this case, the acquisition processing unit 44 may acquire the payout amount of the target sheet by using an average value of multiple elapsed times measured within the specific period up to the present, among multiple elapsed times that have a common combination of the type and size of the sheet SH1.

[0114] 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.

[0115] 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.

[0116] The present invention may also be applied to an inkjet image forming apparatus.

[0117] The present invention may also be applied to the ADF1.

[0118] [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.

[0119] <Appendix 1> a detection unit that detects the sheets supplied by the sheet supply unit in the transport path; a first measurement processing unit that, when the sheet stack is lifted by the lift unit, measures the elapsed time from when the sheet supply unit starts to supply the sheets to when the detection unit detects the sheets; a second measurement processing unit that, after measurement by the first measurement processing unit, measures the elapsed time from when the sheet supply unit starts to supply the sheets to when the detection unit detects the sheets; and an acquisition processing unit that acquires the amount of the acquisition target sheet that was supplied from the sheet stack at the time when the supply of the acquisition target sheet that was supplied at the time of measurement by the second measurement processing unit started based on the measurement results by the first measurement processing unit and the measurement results by the second measurement processing unit.

[0120] <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 first measurement processing section measures the elapsed time from when the sheet supply section starts to supply the sheets to when the detection section detects the sheets when the lift section lifts the sheet stack for the first time after the sheet storage section is attached to the housing.

[0121] <Appendix 3> The sheet conveying device described in Appendix 1 or 2, wherein the first measurement processing unit measures the elapsed time from when the sheet supply unit starts supplying the sheet to when the detection unit detects the sheet each time the sheet stack is lifted by the lift unit, and the acquisition processing unit acquires the amount of the target sheet being paid out from the sheet stack at the time when the supply of the target sheet starts based on the measurement result by the first measurement processing unit immediately before.

[0122] <Appendix 4> A sheet conveying device described in any one of Appendices 1 to 3, wherein the first measurement processing unit measures the elapsed time from when the sheet supply unit starts supplying the sheet to when the detection unit detects the sheet at the first supply of the sheet after the sheet stack is lifted by the lift unit.

[0123] <Appendix 5> The sheet supply unit includes a separation unit that separates an accompanying sheet from the sheet being transported by the transport member, and the sheet transporting device is provided with a determination processing unit that determines whether the target sheet has protruded beyond the separation unit based on the acquisition result by the acquisition processing unit, and a notification processing unit that notifies the user when it is determined that the target sheet has protruded beyond the separation unit.

[0124] <Appendix 6> 6. An image forming apparatus comprising: the sheet conveying device according to any one of claims 1 to 5; and an image forming section that forms an image on the sheet conveyed by the sheet conveying device.

[0125] <Appendix 7> an acquisition method performed by a sheet conveying device having 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: a first measurement step of measuring, when the sheet stack is lifted by the lift section, the elapsed time from when the sheet supply section starts to supply the sheet to when the detection section detects the sheet; a second measurement step of measuring, after measurement by the first measurement step, the elapsed time from when the sheet supply section starts to supply the sheet to when the detection section detects the sheet; and an acquisition step of acquiring the amount of the acquisition target sheet that was supplied at the time of measurement by the second measurement step, based on the measurement results by the first measurement step and the measurement results by the second measurement step, that was fed out of the sheet stack at the time when the supply of the acquisition target sheet that was supplied at the time of measurement by the second measurement step started. [Explanation of symbols]

[0126] 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 28A Separation part 31 Lift Board 41 Displacement processing section 42 First measurement processing section 43 Second measurement processing section 44 Acquisition processing unit 45 Judgment processing unit 46 Notification processing section 100 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; a first measurement processing unit that measures an elapsed time from when the sheet supply unit starts supplying the sheets to when the detection unit detects the sheets when the sheet stack is lifted by the lift unit; a second measurement processing unit that measures an elapsed time from when the sheet supply unit starts supplying the sheet to when the detection unit detects the sheet, after the measurement by the first measurement processing unit; an acquisition processing unit that acquires a payout amount of the acquisition target sheet from the sheet bundle at the start of supply of the acquisition target sheet supplied at the time of measurement by the second measurement processing unit, based on the measurement result by the first measurement processing unit and the measurement result by the second measurement processing 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 first measurement processing unit measures an elapsed time from when the sheet supply unit starts supplying the sheets to when the detection unit detects the sheets, 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 first measurement processing unit measures an elapsed time from when the sheet supply unit starts supplying the sheets to when the detection unit detects the sheets, every time the lift unit lifts the sheet stack; the acquisition processing unit acquires the amount of the acquisition target sheet fed out from the sheet bundle at the start of supply of the acquisition target sheet based on the immediately preceding measurement result by the first measurement processing unit; 3. The sheet conveying device according to claim 1 or 2.

4. the first measurement processing unit measures an elapsed time from when the sheet supply unit starts supplying the sheets to when the detection unit detects the sheets, when the sheets are first supplied after the sheet stack is lifted by the lift unit; 3. The sheet conveying device according to claim 1 or 2.

5. The sheet supply unit includes: a separation unit that separates an accompanying sheet from the sheet conveyed by the conveying member, the sheet conveying device, a determination processing unit that determines whether the acquisition target sheet protrudes beyond the separation unit based on the acquisition result by the acquisition processing unit; a notification processing unit that notifies the user when it is determined that the acquisition target sheet protrudes beyond the separation unit; The sheet conveying device according to claim 1 or 2, comprising:

6. 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:

7. 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, a first measuring step of measuring an elapsed time from when the sheet supply unit starts supplying the sheets to when the detection unit detects the sheets, when the sheet stack is lifted by the lift unit; a second measuring step of measuring an elapsed time from when the sheet supply unit starts supplying the sheet to when the detection unit detects the sheet, after the measurement in the first measuring step; an acquisition step of acquiring a payout amount of the acquisition target sheet from the sheet bundle at the start of supply of the acquisition target sheet supplied at the time of measurement in the second measurement step, based on a measurement result in the first measurement step and a measurement result in the second measurement step; Acquisition methods include:

Images