Paper feeding conveyance device, image forming device, paper feeding performance determination method, and program

Abstract

To provide a paper feeding conveyance device which can detect deterioration in paper feeding performance of a paper feeding roller caused by excessive paper powder on a paper feeding roller surface and can prevent it, even in a state where sheets are loaded on a paper feeding tray, to provide an image forming device, to provide a paper feeding performance determination method and to provide a program.SOLUTION: A paper feeding conveyance device includes: a paper feeding part (paper feeding roller 22) for feeding recording media loaded on a paper feeding tray 21; a drive part (motor 25) for driving the paper feeding part; a first detection part (electric current detection part 30) for detecting an electric current applied to the drive part; and a determination part (control part 11) for determining paper feeding performance of the paper feeding part, based on the detection result by the first detection part, while the recording media are being fed by the paper feeding part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a paper feeding and conveying device, an image forming apparatus, a paper feeding performance determination method, and a program.

Background Art

[0002] Conventionally, an image forming apparatus including a paper feeding and conveying device that feeds and conveys paper (recording medium) to an image forming unit has been known. The paper feeding and conveying device includes a paper feeding roller that conveys paper in a conveying direction, a separation roller that is pressed against the paper feeding roller to form a nip portion and prevent double feeding of the paper, and the like.

[0003] Patent Document 1 discloses a configuration in which the paper feeding roller is cleaned by rotating (idling) the paper feeding roller in a state where the paper is not sandwiched in the nip portion. Specifically, in the configuration described in Patent Document 1, when the number of times the paper feed tray becomes empty reaches a predetermined number of times, the paper feed roller is idled. In the configuration described in Patent Document 1, when the degree of entrainment of the separation roller determined during idling is poor, the predetermined number of times is set to a value smaller than normal. Thereby, the cleaning frequency of the paper feed roller can be increased.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the configuration described in Patent Document 1 is idled when the paper feed tray is empty, the paper feed roller cannot be cleaned when the paper feed tray is loaded with paper. Usually, since a large number of sheets of paper are loaded in the paper feed tray, if the paper feeding performance deteriorates before it becomes empty, the deterioration of the paper feeding performance cannot be detected. Therefore, the configuration described in Patent Document 1 has a problem that a good paper feeding state cannot be maintained.

[0006] An object of the present invention is to provide a paper feeding and conveying device, an image forming apparatus, a paper feeding performance determination method, and a program capable of detecting and preventing a decrease in the paper feeding performance of a paper feeding roller due to excessive paper dust on the surface of the paper feeding roller even when paper is loaded on a paper feeding tray.

Means for Solving the Problems

[0007] The invention according to claim 1 is made to achieve the above object, in a paper feeding and conveying device, a paper feeding unit that feeds a recording medium loaded on a paper feeding tray; a driving unit that drives the paper feeding unit; a first detection unit that detects a current applied to the driving unit; a determination unit that determines the paper feeding performance of the paper feeding unit based on a detection result by the first detection unit while the recording medium is being fed by the paper feeding unit; characterized by comprising.

[0008] The invention according to claim 2 is the paper feeding and conveying device according to claim 1, a second detection unit that detects opening and closing of the paper feeding tray; a first control unit that presses the recording medium against the paper feeding unit; comprising The first control unit presses the recording medium against the paper feeding unit after it is detected by the second detection unit that the paper feeding tray is closed.

[0009] The invention according to claim 3 is the paper feeding and conveying device according to claim 2, comprising a second control unit that drives the paper feeding unit by the driving unit, When the second control unit determines that the paper feeding performance has decreased by the determination unit, after it is detected by the second detection unit that the paper feeding tray is closed and before the pressing by the first control unit is performed, the paper feeding unit is driven for a predetermined time. The first control unit is characterized by performing the pressure contact after the paper feeding unit is driven by the second control unit for the predetermined time.

[0010] The invention according to claim 4 is the paper feeding and conveying apparatus according to claim 3, characterized by comprising a third control unit that causes a display unit to display a notification indicating a decrease in the paper feeding performance and a notification prompting opening and closing of the paper feed tray when the determination unit determines a decrease in the paper feeding performance.

[0011] The invention according to claim 5 is the paper feeding and conveying apparatus according to claim 1, characterized by comprising a pickup roller for picking up the recording medium on the upstream side in the conveyance direction of the recording medium from the paper feeding unit.

[0012] The invention according to claim 6 is the paper feeding and conveying apparatus according to claim 1, wherein the determination unit determines that the paper feeding performance has deteriorated when a variation width of a current value detected by the first detection unit during driving of the paper feeding unit is equal to or greater than a first threshold value.

[0013] The invention according to claim 7 is the paper feeding and conveying apparatus according to claim 1, wherein the determination unit determines that the paper feeding performance has deteriorated when a current value detected by the first detection unit during driving of the paper feeding unit is equal to or less than a second threshold value.

[0014] The invention according to claim 8 is the paper feeding and conveying apparatus according to claim 3, characterized by comprising a third detection unit for detecting the recording medium on the downstream side in the conveyance direction of the recording medium from the paper feeding unit, wherein the second control unit stops driving of the paper feeding unit when the third detection unit detects the recording medium during driving of the paper feeding unit for the predetermined time.

[0015] The invention according to claim 9 is in an image forming apparatus, A paper feeding and conveying device according to any one of claims 1 to 8, an image forming unit that forms an image on the recording medium fed and conveyed by the paper feeding and conveying device, characterized by comprising the same.

[0016] The invention according to claim 10 is a method for determining the paper feeding performance of a paper feeding and conveying device, comprising: a paper feeding unit that feeds a recording medium stacked on a paper feeding tray; a driving unit that drives the paper feeding unit; and a first detection unit that detects a current applied to the driving unit, including a determination step of determining the paper feeding performance of the paper feeding unit based on the detection result of the first detection unit while the paper feeding unit is feeding the recording medium.

[0017] The invention according to claim 11 is a program for causing a computer of a paper feeding and conveying device, which includes a paper feeding unit that feeds a recording medium stacked on a paper feeding tray, a driving unit that drives the paper feeding unit, and a first detection unit that detects a current applied to the driving unit, to function as a determination unit that determines the paper feeding performance of the paper feeding unit based on the detection result of the first detection unit while the paper feeding unit is feeding the recording medium.

Advantages of the Invention

[0018] According to the present invention, even when paper is stacked on the paper feeding tray, it is possible to detect and prevent a decrease in the paper feeding performance of the paper feeding roller due to excessive paper dust on the surface of the paper feeding roller.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0021] As shown in FIGS. 1 and 2, the image forming apparatus 1 according to the present embodiment includes a control unit 11, an image reading unit 12, an image forming unit 13, a storage unit 14, an operation panel 15, a communication unit 16, and a paper feeding and conveyance unit 20. Note that the paper feeding and conveyance apparatus of the present invention includes at least the control unit 11 and the paper feeding and conveyance unit 20.

[0022] The control unit 11 includes a CPU, a RAM, a ROM, etc. First, the CPU reads out various processing programs stored in the ROM according to various signals and expands them in the RAM. The various signals are operation signals input from the operation unit 152 or instruction signals received by the communication unit 16. Next, the CPU comprehensively controls the operation of the image forming apparatus 1 in cooperation with the various programs expanded in the RAM.

[0023] The image reading unit 12 first scans and exposes the image of the document placed on the document table or the automatic document feeder (ADF) with the optical system of the scanning exposure device. Next, the image reading unit 12 reads the reflected light with a line image sensor to obtain an image signal. This image signal is input to the control unit 11 as image data after being subjected to processes such as A / D conversion, shading correction, and compression. Note that the image data input to the control unit 11 is not limited to that read by the image reading unit 12. For example, the image data input to the control unit 11 may be received from an external device (not shown) via the communication unit 16.

[0024] The image forming unit 13 forms an image consisting of four colors, C, M, Y, and K, on the paper according to the pixel values of the four colors of each pixel of the image-processed original image. The image forming unit 13 forms an image on the paper fed and conveyed by the paper feeding and conveying unit 20. As shown in FIG. 1, the image forming unit 13 includes four writing units 131, an intermediate transfer belt 132, a secondary transfer roller 133, a fixing unit 134, and the like.

[0025] The four writing units 131 are arranged in series (tandem) along the belt surface of the intermediate transfer belt 132 to form images of each color of C, M, Y, and K. Each writing unit 131 includes an exposure unit 131a, a photoreceptor 131b, a developing unit 131c, a charging unit 131d, a cleaning unit 131e, and a primary transfer roller 131f. Each writing unit 131 has the same configuration except for the different colors of the images to be formed.

[0026] During image formation, each writing unit 131 charges the photoreceptor 131b with the charging unit 131d. Then, the exposure unit 131a scans the photoreceptor 131b with a light beam emitted based on the original image to form an electrostatic latent image on the photoreceptor 131b. Next, the developing unit 131c supplies a coloring material such as toner to the electrostatic latent image formed on the photoreceptor 131b for development. Thereby, the image forming unit 13 forms an image (toner image) on the photoreceptor 131b. Next, each primary transfer roller 131f sequentially superposes and primarily transfers the images formed on the photoreceptor 131b onto the intermediate transfer belt 132. As a result, an image composed of each color is formed on the intermediate transfer belt 132. The intermediate transfer belt 132 is an image carrier that is wound around a plurality of rollers and rotates. The cleaning unit 131e removes the toner remaining on the photoreceptor 131b after the primary transfer.

[0027] In the image forming unit 13, paper is fed from the manual tray T1 or the paper feeding and conveying unit 20 in accordance with the timing when the image on the rotating intermediate transfer belt 132 reaches the position of the secondary transfer roller 133. The secondary transfer roller 133 is one of a plurality of rollers in which one of the pair of rollers is in pressure contact with the intermediate transfer belt 132 and the other roller winds around the intermediate transfer belt 132. The secondary transfer roller 133 secondarily transfers the image from the intermediate transfer belt 132 onto the paper by pressure contact and conveys the paper to the fixing unit 134. The fixing unit 134 performs a fixing process on the conveyed paper. The fixing process is a process of heating and pressurizing the paper by the fixing roller 134a to fix the image on the paper. The paper on which the fixing process has been performed by the fixing unit 134 is discharged to the paper discharge tray T2 by the paper discharge roller R1. The reverse path 135 reverses the paper surface of the conveyed paper when forming images on both sides of the paper, and then feeds the paper again to the position of the secondary transfer roller 133.

[0028] The storage unit 14 is a non-volatile storage means composed of an HDD (Hard Disk Drive), an SSD (solid state drive), etc. The storage unit 14 can read and write various programs, various setting data, etc. from and to the control unit 11.

[0029] The operation panel 15 includes a display unit 151 that displays various information to the user, and an operation unit 152 that receives operation inputs from the user. The display unit 151 is composed of a color liquid crystal display or the like. The display unit 151 displays an operation screen etc. (various setting screens, various buttons, operation statuses of each function, etc.) in accordance with the display control signal input from the control unit 11. The operation unit 152 includes a touch panel provided on the screen of the display unit 151 and various hard keys arranged around the screen of the display unit 151. When a button displayed on the screen is pressed by a finger, a touch pen, or the like, the operation unit 152 first detects the XY coordinates of the pressing force point as voltage values. Next, the operation unit 152 outputs an operation signal associated with the detected position to the control unit 11. Note that the touch panel is not limited to a pressure-sensitive type, and may be, for example, an electrostatic type or an optical type. Also, when a hard key is pressed, the operation unit 152 outputs an operation signal associated with the pressed key to the control unit 11. The user can operate the operation unit 152 to perform settings related to image formation, paper conveyance instructions, and device stop operations. Settings related to image formation include image quality settings, magnification settings, application settings, output settings, and paper settings, etc.

[0030] The communication unit 16 is an interface for connecting the image forming apparatus 1 to a communication network. The communication unit 16 includes a communication IC, a communication connector, and the like. Under the control of the control unit 11, the communication unit 16 performs transmission and reception of various information with an external device connected to the communication network using a predetermined communication protocol. Also, the communication unit 16 can input and output various information via USB.

[0031] As shown in FIG. 1, a plurality of paper feeding and conveying units 20 are provided. Each paper feeding and conveying unit 20 supplies the paper P toward the image forming unit 13. As shown in FIGS. 2 and 3, each paper feeding and conveying unit 20 includes a paper feed tray 21, a paper feed roller 22, a separation roller 23, a pickup roller 24, a motor 25, a lifting plate 26, a lift-up motor 27, an upper limit sensor 28, a lower limit sensor 29, a current detection unit 30, and an open / close detection unit 31.

[0032] The paper feed tray 21 stores papers P of a predetermined paper type and size. The paper feed tray 21 is configured to be insertable and removable.

[0033] The paper feed roller (paper feed unit) 22 feeds the paper (recording medium) P stacked on the paper feed tray 21. The paper feed roller 22 is installed on the leading end side in the conveyance direction with respect to the paper P stacked on the elevating plate 26. The paper feed roller 22 rotates counterclockwise along the conveyance direction of the paper P while being in contact with the upper surface of the paper P. Thereby, the paper feed roller 22 feeds the paper P in the conveyance direction.

[0034] The separation roller 23 is installed so as to form a nip portion with the paper feed roller 22. When one sheet of paper P is sandwiched in the nip portion, the separation roller 23 rotates clockwise along the conveyance direction (symbol X in FIG. 4) of the paper P. Further, when no paper P is sandwiched in the nip portion, the separation roller 23 rotates clockwise along the conveyance direction of the paper P. On the other hand, when a plurality of sheets of paper P are sandwiched in the nip portion, the separation roller 23 separates the lower paper P2 from the uppermost paper P1 (see FIG. 4). Thereby, only the uppermost paper P1 is fed in the conveyance direction along with the rotation of the paper feed roller 22. Specifically, the separation roller 23 rotates counterclockwise along the direction opposite to the conveyance direction of the paper P. Thereby, the lower paper P2 is conveyed in the direction opposite to the conveyance direction along with the rotation of the separation roller 23.

[0035] A torque limiter 231 is installed on the shaft portion of the separation roller 23. The driving of the motor 25 is transmitted or blocked to / from the separation roller 23 via the torque limiter 231. When a rotational load exceeding a predetermined value is applied to the separation roller 23, the torque limiter 231 is configured such that the separation roller 23 idles relative to the torque limiter 231. Specifically, when one sheet of paper P is sandwiched between the nip portions and when no paper P is sandwiched between the nip portions, the torque limiter 231 cuts off the drive transmission from the motor 25 to the separation roller 23. This is because the rotational load applied to the separation roller 23 becomes relatively large. At this time, the separation roller 23 rotates idly with respect to the torque limiter 231. As a result, the separation roller 23 rotates clockwise (rotates as a follower) along with the rotation of the paper feed roller 22. On the other hand, when a plurality of sheets of paper P are sandwiched between the nip portions, the torque limiter 231 transmits the drive from the motor 25 to the separation roller 23. This is because the rotational load applied to the separation roller 23 becomes relatively small due to the slippage between the sheets of paper P. As a result, the separation roller 23 is rotationally driven counterclockwise. Therefore, the lower sheets of paper P2, excluding the uppermost sheet of paper P1 among the plurality of sheets of paper P sandwiched between the nip portions, are conveyed in the reverse direction of the conveyance direction and returned to the lifting plate 26. With the above configuration, only one sheet of paper P is sent out in the conveyance direction from the nip portion between the paper feed roller 22 and the separation roller 23 without double feeding of the paper P.

[0036] The pickup roller 24 is installed upstream of the paper feed roller 22 in the conveyance direction of the paper P and is a roller for picking up the paper P. As shown in FIG. 4, the surface of the pickup roller 24 has an uneven shape. The pickup roller 24 rotates counterclockwise along the conveyance direction of the paper P while in contact with the upper surface of the paper P stacked on the lifting plate 26. As a result, the pickup roller 24 conveys the paper P toward the position of the paper feed roller 22.

[0037] The motor (drive unit) 25 functions as a drive source for rotationally driving the paper feed roller 22, the separation roller 23, and the pickup roller 24. The motor 25 is feedback-controlled so that the rotational speed of the shaft becomes a predetermined value. Specifically, the control unit 11 adjusts the applied current by PWM control so that the rotational speed of the motor 25 remains constant regardless of load fluctuations. For example, when the load applied to the motor 25 is large, the control unit 11 adjusts the applied current to increase. On the other hand, when the load applied to the motor 25 is small, the control unit 11 adjusts the applied current to decrease. Thereby, the rotational speed of the motor 25 is made constant. Therefore, stable paper feeding by the paper feed conveyance unit 20 becomes possible.

[0038] The lift plate 26 is provided at the bottom of the paper feed tray 21. The lift plate 26 moves up and down in the vertical direction so that the pickup roller 24 can contact the uppermost sheet P stacked on the lift plate 26. The lift plate 26 moves up and down in the vertical direction by a lift-up motor 27. The lift plate 26 moves up and down in the vertical direction according to the number of sheets P stacked. The lift plate 26 rises to a position where the pickup roller 24 contacts the uppermost sheet P stacked on the lift plate 26. Thereby, the paper feeding and conveyance operation of the sheet P is performed.

[0039] The lift-up motor 27 is a drive source for moving the lift plate 26 up and down in the vertical direction. The lift-up motor 27 rotates clockwise to raise the lift plate 26. The lift-up motor 27 rotates counterclockwise to lower the lift plate 26.

[0040] The upper limit sensor 28 detects that the uppermost sheet P loaded on the lifting plate 26 has reached the upper limit. That is, the upper limit sensor 28 detects a state where the pickup roller 24 abuts against the upper surface of the uppermost sheet P loaded on the lifting plate 26. When the upper limit sensor 28 detects that the uppermost sheet P has reached the upper limit, the pickup roller 24 starts to be rotationally driven counterclockwise. As a result, the uppermost sheet P loaded on the lifting plate 26 is conveyed toward the nip portion of the paper feed roller 22 and the separation roller 23. Also, at the same timing as the rotational drive of the pickup roller 24, the paper feed roller 22 and the separation roller 23 start to be rotationally driven. As a result, one sheet of paper P is separated from the nip portion of the paper feed roller 22 and the separation roller 23 and conveyed toward the image forming unit 13.

[0041] The lower limit sensor 29 detects that the lifting plate 26 has reached the lower limit.

[0042] The current detection unit 30 detects the current applied to the motor 25. That is, the current detection unit 30 functions as the first detection unit of the present invention. The current detection unit 30 detects a change in the load torque applied to the motor 25 by detecting a change in the current applied to the motor 25. As the current detection unit 30, for example, a current measuring device that detects a change in the current applied to the motor 25 can be used.

[0043] The opening / closing detection unit 31 detects the opening and closing of the paper feed tray 21. That is, the opening / closing detection unit 31 functions as the second detection unit of the present invention. The opening / closing detection unit 31 outputs the detected information (the fact that the paper feed tray 21 has been opened or closed) to the control unit 11. After the control unit 11 detects that the paper feed tray 21 has been closed by the opening / closing detection unit 31, it presses the sheet P against the paper feed roller 22.

[0044] Also, a paper feed sensor SE1 is provided on the downstream side in the conveyance direction of the sheet P from the paper feed conveyance unit 20. The paper feed sensor SE1 is, for example, an optical sensor that optically detects the passing sheet P. That is, the paper feed sensor SE1 functions as the third detection unit of the present invention.

[0045] Next, the control of the image forming apparatus 1 according to the present embodiment will be described with reference to the flowchart of FIG. 5. The control in FIG. 5 starts when the paper feeding and conveying by the paper feeding and conveying unit 20 is started.

[0046] First, the control unit 11 performs a paper feeding performance determination of the paper feeding roller 22 during paper feeding by the paper feeding and conveying unit 20 (step S101). Specifically, the control unit 11 performs the paper feeding performance determination based on the fluctuation range (P-P) of the current value detected by the current detection unit 30 during the driving of the paper feeding roller 22. That is, the control unit 11 functions as a determination unit of the present invention that determines the paper feeding performance of the paper feeding roller 22 based on the detection result by the current detection unit 30 while the paper P is being fed by the paper feeding roller 22.

[0047] Generally, the more the amount of paper dust on the surface of the paper feeding roller 22, the lower the paper feeding performance of the paper feeding roller 22. Therefore, the load applied to the pickup roller 24 increases. Since the surface of the pickup roller 24 has irregularities, the load applied to the pickup roller 24 appears as a periodic component with respect to the torque current of the motor 25. That is, as the amount of paper dust on the surface of the paper feeding roller 22 increases and the load applied to the pickup roller 24 increases, the periodic component of the torque current becomes larger. Thereby, the fluctuation range (P-P) of the torque current of the motor 25 becomes larger. Therefore, by referring to the P-P of the torque current of the motor 25, the paper feeding performance of the paper feeding roller 22 can be determined.

[0048] FIG. 6 is a diagram for explaining the paper feeding performance determination of the paper feeding roller 22. FIG. 6(A) is a diagram showing an example of the value of the torque current of the motor 25 during paper feeding. FIG. 6(B) is an enlarged view of a part (the range indicated by the symbol G) of FIG. 6(A). FIG. 6(C) is a diagram showing the maximum value, minimum value, P-P, and average value of the torque current in FIG. 6(A). In FIG. 6, the left diagram is for the case where there is no paper dust. The middle diagram is for the case where there is a small amount of paper dust. The right diagram is for the case where there is a large amount of paper dust (a situation where paper jams frequently occur). The symbol H in FIG. 6(B) indicates the P-P of the torque current of the motor 25. In the example shown in FIG. 6, it can be seen that the P-P value increases as the amount of paper dust increases. That is, by referring to the P-P of the torque current of the motor 25, the paper feeding performance of the paper feeding roller 22 can be determined. Specifically, when the fluctuation range (P-P) of the current value detected by the current detection unit 30 during the driving of the paper feeding roller 22 is equal to or greater than the first threshold value, the control unit 11 determines that the paper feeding performance of the paper feeding roller 22 has deteriorated. The first threshold value is a value smaller than the fluctuation range of the paper feeding performance limit at which paper feeding becomes impossible. That is, the first threshold value is a value for determining the state just before reaching the paper feeding performance limit.

[0049] Next, the control unit 11 determines whether the fluctuation range of the current value has reached the first threshold value (step S102). When the control unit 11 determines that the fluctuation range of the current value has reached the first threshold value (step S102: YES), it determines that the paper feeding performance of the paper feeding roller 22 has deteriorated and proceeds to the next step S103. On the other hand, when the control unit 11 determines that the fluctuation range of the current value has not reached the first threshold value (step S102: YES), it proceeds to step S101.

[0050] In step S103, the control unit 11 temporarily stops the paper feeding by the paper feeding conveyance unit 20.

[0051] Next, the control unit 11 causes the display unit 151 to display a notification prompting the user to open and close the paper feed tray 21 (step S104). At this time, the control unit 11 also causes the display unit 151 to display a notification indicating a decrease in the paper feed performance of the paper feed roller 22. That is, when it is determined that the paper feed performance has decreased, the control unit 11 functions as the third control unit of the present invention that causes the display unit 151 to display a notification indicating a decrease in the paper feed performance and a notification prompting the opening and closing of the paper feed tray 21.

[0052] Next, the control unit 11 determines whether the opening and closing of the paper feed tray 21 is detected by the opening / closing detection unit 31 (step S105). When the control unit 11 determines that the opening and closing of the paper feed tray 21 is detected (step S105: YES), it proceeds to the next step S106. On the other hand, when the control unit 11 determines that the opening and closing of the paper feed tray 21 is not detected (step S105: NO), it repeats the process of step S105.

[0053] In this embodiment, when the opening operation of the paper feed tray 21 is detected, the lifting plate 26 descends (lifts down). As a result, the sheet P is separated from the paper feed roller 22. In this embodiment, thereafter, even when the closing operation of the paper feed tray 21 is detected, the lifting plate 26 is not lifted up (lifted). As a result, the sheet P remains separated from the paper feed roller 22 even after the closing operation of the paper feed tray 21.

[0054] In step S106, the control unit 11 starts driving (rotating) the paper feed roller 22. That is, the control unit 11 functions as the second control unit of the present invention that drives the paper feed roller 22 by the motor 25. In step S106, since the sheet P is separated from the paper feed roller 22, the paper feed roller 22 rotates idly. As a result, the paper dust adhering to the surface of the paper feed roller 22 can be scattered. Therefore, the paper feed roller 22 can be cleaned.

[0055] Next, the control unit 11 determines whether or not a predetermined time has elapsed since the driving of the paper feed roller 22 was started (step S107). The predetermined time is the time required for the performance recovery by cleaning the paper feed roller 22, and is, for example, 10 seconds. If the control unit 11 determines that the predetermined time has elapsed (step S107: YES), it proceeds to step S109. On the other hand, if the control unit 11 determines that the predetermined time has not elapsed (step S107: NO), it proceeds to the next step S108.

[0056] In step S108, the control unit 11 determines whether or not the sheet P has been detected by the paper feed sensor SE1. That is, the control unit 11 determines whether or not the uppermost sheet P has been fed contrary to intention by the driving (idle rotation) of the paper feed roller 22. If the control unit 11 determines that the sheet P has been detected (step S108: YES), it proceeds to the next step S109. On the other hand, if the control unit 11 determines that the sheet P has not been detected (step S108: NO), it proceeds to step S107.

[0057] In step S109, the control unit 11 stops the driving (idle rotation) of the paper feed roller 22. That is, when the control unit 11 determines that the predetermined time has elapsed since the driving of the paper feed roller 22 was started, it stops the driving of the paper feed roller 22. Further, when the sheet P is detected by the paper feed sensor SE1 while the paper feed roller 22 is being driven for the predetermined time, the control unit 11 stops the driving of the paper feed roller 22.

[0058] Next, the control unit 11 controls the lift-up motor 27 to raise (lift up) the lift plate 26 (step S110). Thereby, the control unit 11 presses the sheet P against the paper feed roller 22. That is, the control unit 11 functions as the first control unit of the present invention.

[0059] Next, the control unit 11 resumes the paper feed by the paper feed conveyance unit 20 (step S111).

[0060] As described above, when it is determined that the paper feeding performance has deteriorated, the control unit 11 drives the paper feeding roller 22 for a predetermined time. Specifically, the control unit 11 drives the paper feeding roller 22 for a predetermined time after it is detected by the opening / closing detection unit 31 that the paper feeding tray 21 has been closed and before the paper P is pressed against the paper feeding roller 22. Then, after the paper feeding roller 22 has been driven for a predetermined time, the control unit 11 presses the paper P against the paper feeding roller 22.

[0061] FIG. 7 shows an example of maintaining the paper feeding performance by cleaning the paper feeding roller 22. The horizontal axis in FIG. 7 represents time, and the vertical axis represents the value of the torque current of the motor 25. In FIG. 7, the symbol JL1 represents the value of the paper feeding performance limit, and the symbol J1 represents the first threshold value. As described with reference to FIG. 6, the larger the P-P of the torque current of the motor 25 is, the more the paper feeding performance of the paper feeding roller 22 deteriorates. When the fluctuation range (P-P) of the current value detected by the current detection unit 30 reaches the first threshold value J1 (see the symbol N1), the control unit 11 temporarily stops the subsequent paper feeding. Then, in order to clean the paper feeding tray 21, the control unit 11 causes the display unit 151 to display a notification prompting the user to open and close the paper feeding tray 21. When the user opens the paper feeding tray 21, the lifting plate 26 descends. As a result, when the user closes the paper feeding tray 21 again, the paper P does not contact the pickup roller 24. When the control unit 11 detects that the user has closed the paper feeding tray 21, the control unit 11 performs idling rotation of the paper feeding roller 22. Thereby, it is possible to remove the paper dust on the surface of the paper feeding roller 22, which is a factor in the deterioration of the paper feeding performance. Then, when the idling rotation of the paper feeding roller 22 is completed, the control unit 11 raises (lifts up) the lifting plate 26. After that, paper feeding is started as usual, and the monitoring of the torque current of the motor 25 is continued. In the example shown in FIG. 7, it can be seen that after the idling rotation of the paper feeding roller 22 is performed (see the symbol N2), the fluctuation range of the torque current of the motor 25 becomes smaller. That is, it can be seen that the paper feeding performance of the paper feeding roller 22 has recovered.

[0062] When there is a large amount of paper P stacked on the paper feed tray 21, the paper P and the pickup roller 24 may come into contact even without lifting up the lifting plate 26. If the paper feed roller 22 is idled in this state, the uppermost paper P will be fed. Therefore, the paper feed sensor SE1 is monitored during the idling of the paper feed roller 22. When the paper feed sensor SE1 detects the paper P, the control unit 11 interrupts the idling of the paper feed roller 22. Thereby, it is possible to prevent the uppermost paper P from being fed during the idling operation.

[0063] As described above, the image forming apparatus 1 according to the present embodiment includes a paper feed unit, a drive unit, a first detection unit, and a determination unit. The paper feed unit (paper feed roller 22) feeds the recording medium (paper P) stacked on the paper feed tray 21. The drive unit (motor 25) drives the paper feed unit. The first detection unit (current detection unit 30) detects the current applied to the drive unit. The determination unit (control unit 11) determines the paper feed performance of the paper feed unit based on the detection result by the first detection unit while the recording medium is being fed by the paper feed unit. Therefore, according to the image forming apparatus 1 according to the present embodiment, even when the paper is stacked on the paper feed tray 21, it is possible to detect and prevent a decrease in the paper feed performance of the paper feed unit due to excessive paper dust on the surface of the paper feed unit.

[0064] Further, it includes a second detection unit (open / close detection unit 31) for detecting the opening and closing of the paper feed tray 21, and a first control unit (control unit 11) for pressing the recording medium against the paper feed unit. The first control unit presses the recording medium against the paper feed unit after the second detection unit detects that the paper feed tray 21 has been closed. Therefore, when the paper feed tray 21 is closed, it is possible to arrange a situation where the paper feeding by the paper feed unit can be automatically restarted. Thus, the paper feeding by the paper feed unit can be restarted without bothering the user.

[0065] Also, it includes a second control unit (control unit 11) that drives the paper feeding unit by a driving unit. When the determination unit determines a decrease in paper feeding performance, the second control unit drives the paper feeding unit for a predetermined time after it is detected by the second detection unit that the paper feeding tray 21 is closed and before the pressing by the first control unit is performed. The first control unit performs pressing after the paper feeding unit is driven by the second control unit for a predetermined time. Therefore, the paper feeding unit can be idled. Thereby, the paper dust adhering to the surface of the paper feeding unit can be scattered, and the paper feeding unit can be cleaned. Thus, the paper feeding performance of the paper feeding unit can be restored.

[0066] Also, when the determination unit determines a decrease in paper feeding performance, it includes a third control unit (control unit 11) that causes the display unit 151 to display a notification indicating the decrease in paper feeding performance and a notification prompting the opening and closing of the paper feeding tray 21. Therefore, the user can open and close the paper feeding tray 21. Thereby, the lifting plate 26 can be lowered, so that the idling of the paper feeding roller 22 can be performed. Thus, the paper feeding unit can be cleaned.

[0067] Also, it includes a pickup roller 24 for picking up a recording medium upstream of the paper feeding unit in the conveyance direction of the recording medium. Therefore, the paper feeding by the paper feeding roller 22 can be performed smoothly.

[0068] Also, when the fluctuation range of the current value detected by the first detection unit during the driving of the paper feeding unit is equal to or greater than the first threshold value, the determination unit determines that the paper feeding performance has deteriorated. Therefore, even when the paper is loaded on the paper feeding tray 21, it is possible to determine a decrease in paper feeding performance. Thus, a good paper feeding state can be maintained.

[0069] Also, it includes a third detection unit (paper feeding sensor SE1) for detecting a recording medium downstream of the paper feeding unit in the conveyance direction of the recording medium. When the recording medium is detected by the third detection unit while the second control unit is driving the paper feeding unit for a predetermined time, the second control unit stops the driving of the paper feeding unit. Therefore, it is possible to prevent the uppermost sheet P from being fed while idling rotation is being performed. Thus, unintended sheet feeding can be prevented for the user.

[0070] As described above, the embodiments according to the present invention have been specifically described. However, the present invention is not limited to the above embodiments and can be modified without departing from the gist thereof.

[0071] (Modification Example 1) For example, in the above embodiment, after determining a decrease in paper feeding performance, subsequent paper feeding is temporarily stopped and a notification prompting opening and closing of the paper feed tray 21 is displayed. However, the present invention is not limited to this. For example, even if a decrease in paper feeding performance is determined, a notification prompting opening and closing of the paper feed tray 21 may be displayed without temporarily stopping paper feeding, and subsequent paper feeding may be temporarily stopped when the user's approval is obtained. Thereby, it is possible to prioritize the most recent productivity. It is assumed that the criteria for the user to prioritize prevention of paper jams by maintaining paper feeding performance or to prioritize the most recent productivity are different. Therefore, a configuration may be adopted that allows selection between the configuration of the embodiment that prioritizes prevention of paper jams and the configuration of Modification Example 1 that prioritizes the most recent productivity. Hereinafter, control of the image forming apparatus 1 according to Modification Example 1 will be described with reference to the flowchart of FIG. 8.

[0072] First, the processes of step S201 and step S202 are the same as the processes of step S101 and step S102 in FIG. 5, and thus the description thereof will be omitted.

[0073] In step S203, the control unit 11 causes the display unit 151 to display a notification prompting the user to open and close the paper feed tray 21. The user performs a selection operation of approval or rejection on the notification displayed on the display unit 151 via the operation unit 152.

[0074] Next, the control unit 11 determines whether or not a selection operation on the notification has been performed by the user (step S204). When the control unit 11 determines that a selection operation has been performed (step S204: YES), it proceeds to the next step S205. On the other hand, when the control unit 11 determines that no selection operation has been performed (step S204: NO), it repeats the process of step S204.

[0075] In step S205, the control unit 11 determines whether the opening and closing of the paper feed tray 21 has been approved by the user. That is, the control unit 11 determines whether the selection operation performed by the user is an approval. When the control unit 11 determines that the opening and closing of the paper feed tray 21 has been approved (step S205: YES), it proceeds to the next step S206. On the other hand, when the control unit 11 determines that the opening and closing of the paper feed tray 21 has not been approved (i.e., rejected) (step S205: NO), it ends the process.

[0076] In step S206, the control unit 11 temporarily stops the paper feeding by the paper feed conveyance unit 20.

[0077] Hereinafter, the processes of steps S207 to S213 are the same as the processes of steps S105 to S111 in FIG. 5, so the description is omitted.

[0078] As described above, when the paper feeding performance deteriorates and the user's approval is obtained, by temporarily stopping the subsequent paper feeding, it is possible to prioritize the most recent productivity.

[0079] (Modification 2) Also, in the above embodiment, a configuration in which the paper feed conveyance unit 20 includes the pickup roller 24 is illustrated and described, but it is not limited thereto. For example, as shown in FIG. 9, the paper feed conveyance unit 20A may have a configuration that does not include the pickup roller 24.

[0080] FIG. 10 is a diagram for explaining the paper feeding performance determination of the paper feeding roller 22 in Modification 2. FIG. 10(A) is a diagram showing an example of the value of the torque current of the motor 25 during paper feeding. FIG. 10(B) is a diagram showing the average value of the torque current in FIG. 10(A). In FIG. 10, the left diagram is for the case where there is no paper dust. The middle diagram is for the case where there is a small amount of paper dust. The right diagram is for the case where there is a large amount of paper dust (a situation where paper jams frequently occur). Generally, the more paper dust on the surface of the paper feeding roller 22, the lower the paper feeding performance of the paper feeding roller 22. Therefore, the load applied to the paper feeding roller 22 decreases. As a result, the average value of the torque current of the motor 25 becomes smaller. In the example shown in FIG. 10, it can be seen that the value of the average value decreases as the amount of paper dust increases. Therefore, by referring to the average value of the torque current of the motor 25, the paper feeding performance of the paper feeding roller 22 can be determined. Specifically, when the current value detected by the current detection unit 30 during the driving of the paper feeding roller 22 is equal to or less than the second threshold value, the control unit 11 determines that the paper feeding performance of the paper feeding roller 22 has deteriorated. The second threshold value is a value larger than the value of the paper feeding performance limit at which paper feeding becomes impossible. That is, the second threshold value is a value for determining the state just before reaching the paper feeding performance limit.

[0081] FIG. 11 shows an example of maintaining the paper feeding performance by cleaning the paper feeding roller 22 in Modification 2. The horizontal axis in FIG. 11 represents time, and the vertical axis represents the average value of the torque current of the motor 25. In FIG. 11, the symbol JL2 is the value of the paper feeding performance limit, the symbol J2 is the second threshold value, and the symbol J0 is the normal value. As described with reference to FIG. 10, as the paper feeding performance of the paper feeding roller 22 deteriorates, the average value of the torque current of the motor 25 decreases. When the average value of the current value detected by the current detection unit 30 reaches the second threshold value J2 (see reference sign N3), the control unit 11 temporarily stops the subsequent paper feeding. Then, in order to clean the paper feed tray 21, the control unit 11 causes the display unit 151 to display a notification prompting the user to open and close the paper feed tray 21. When the user opens the paper feed tray 21, the lifting plate 26 descends. As a result, when the user closes the paper feed tray 21 again, the sheet P is in a state of not contacting the paper feed roller 22. When the control unit 11 detects that the user has closed the paper feed tray 21, the control unit 11 performs idling rotation of the paper feed roller 22. Thereby, it is possible to remove paper dust on the surface of the paper feed roller 22, which is a factor in the deterioration of the paper feeding performance. Then, when the idling rotation of the paper feed roller 22 is completed, the control unit 11 raises (lifts up) the lifting plate 26. Thereafter, paper feeding is started as in the normal state, and the monitoring of the average value of the torque current of the motor 25 is continued. In the example shown in FIG. 11, it can be seen that after the idling rotation of the paper feed roller 22 (see reference sign N4), the average value of the torque current of the motor 25 has returned to the normal value J0. That is, it can be seen that the paper feeding performance of the paper feed roller 22 has recovered.

[0082] In Modification 2, when the current value detected by the current detection unit 30 during the driving of the paper feed roller 22 is equal to or less than the second threshold value, the control unit 11 determines that the paper feeding performance has deteriorated. Therefore, even when the paper is loaded on the paper feed tray 21, it is possible to determine the deterioration of the paper feeding performance. Thus, a good paper feeding state can be maintained.

[0083] Note that in Modification 2, the configuration in which the paper feed conveyance unit 20 does not include the pickup roller 24 is illustrated and described, but the present invention is not limited thereto. For example, the paper feed conveyance unit 20 may be configured to include a pickup roller having a flat surface shape that is not an uneven shape. In the case of a configuration including a pickup roller having a flat surface shape, similar to the configuration of Modification 2, the paper feeding performance of the paper feed roller 22 can be determined by referring to the average value of the torque current of the motor 25.

[0084] (Other Modification Examples) Also, in the above embodiment, when the paper feed sensor SE1 detects the paper P before a predetermined time has elapsed since the drive (idle rotation) of the paper feed roller 22 started, the drive of the paper feed roller 22 is stopped and the process returns to the normal paper feed operation. However, the present invention is not limited to this. For example, instead of returning to the normal paper feed operation, the display unit 151 may display that the cleaning (idle rotation) of the paper feed roller 22 is an error. In this case, since there is too much paper P stacked on the paper feed tray 21, it is advisable to also notify the user to remove several sheets of paper P from the paper feed tray 21.

[0085] Also, instead of returning to the normal paper feed operation, the paper may be left untouched (paper P may be fed) for a while. In this case, when several sheets of paper P have been fed, the paper P will not come into contact with the pickup roller 24. By idling the paper feed roller 22 in this state, the paper feed roller 22 can be cleaned. After that, the idling is stopped at the timing when a predetermined time has elapsed since the paper P stopped contacting the pickup roller 24, and the process returns to the normal paper feed operation. The state where the paper P does not contact the pickup roller 24 can be estimated from the timing when the paper feed sensor SE1 stops detecting the paper P. Thereby, the paper feed performance of the paper feed roller 22 can be restored.

[0086] In addition, regarding the detailed configuration of each device constituting the image forming apparatus and the detailed operation of each device, appropriate changes can be made as long as they do not depart from the spirit of the present invention.

Explanation of Reference Numerals

[0087] 1 Image forming apparatus 11 Control unit (judgment unit, first control unit, second control unit, third control unit) 12 Image reading unit 13 Image forming unit 131 Writing unit 131a Exposure unit 131b Photoconductor 131c Developing unit 131d Charging unit 131e Cleaning unit 131f Primary transfer roller 132 Intermediate transfer belt 133 Secondary transfer roller 134 Fixing unit 14 Memory unit 15 Operation panel 151 Display unit 152 Operation unit 16 Communication unit 20 Paper feeding and conveying unit 21 Paper feed tray 22 Paper feed roller (paper feeding unit) 23 Separation roller 231 Torque limiter 24 Pickup roller 25 Motor (drive unit) 26 Lifting plate 27 Lift-up motor 28 Upper limit sensor 29 Lower limit sensor 30 Current detection unit (first detection unit) 31 Opening / closing detection unit (second detection unit) SE1 Paper feed sensor (third detection unit) P Paper (recording medium)

Claims

1. A paper feeding unit that feeds a recording medium stacked on a paper feed tray, A drive unit that drives the paper feeding unit, A first detection unit that detects a current applied to the drive unit, A determination unit that determines the paper feeding performance of the paper feeding unit based on the detection result of the first detection unit while the recording medium is being fed by the paper feeding unit, A paper feeding and conveying device, characterized by comprising the above.

2. A second detection unit that detects the opening and closing of the paper feed tray, A first control unit that presses the recording medium against the paper feeding unit, Comprising, The first control unit presses the recording medium against the paper feeding unit after it is detected by the second detection unit that the paper feed tray has been closed, and the paper feeding and conveying device according to claim 1, characterized in that.

3. Comprising a second control unit that drives the paper feeding unit by the drive unit, When the second control unit determines that the paper feeding performance has deteriorated, after it is detected by the second detection unit that the paper feed tray has been closed and before the pressing by the first control unit is performed, the paper feeding unit is driven for a predetermined time, The first control unit performs the pressing after the paper feeding unit is driven for the predetermined time by the second control unit, and the paper feeding and conveying device according to claim 2, characterized in that.

4. Comprising a third control unit that causes a display unit to display a notification indicating a decrease in the paper feeding performance and a notification prompting the opening and closing of the paper feed tray when the determination unit determines that the paper feeding performance has deteriorated, and the paper feeding and conveying device according to claim 3, characterized in that.

5. A pickup roller for picking up the recording medium is provided upstream of the paper feeding unit in the conveying direction of the recording medium, and the paper feeding and conveying device according to claim 1, characterized in that.

6. The determination unit determines that the paper feeding performance has deteriorated when the fluctuation range of the current value detected by the first detection unit during the driving of the paper feeding unit is equal to or greater than a first threshold value. The paper feeding and conveying device according to claim 1, characterized in that.

7. The determination unit determines that the paper feeding performance has deteriorated when the current value detected by the first detection unit during the driving of the paper feeding unit is equal to or less than a second threshold value. The paper feeding and conveying device according to claim 1, characterized in that.

8. A third detection unit for detecting the recording medium is provided on the downstream side of the paper feeding unit in the conveying direction of the recording medium. When the recording medium is detected by the third detection unit during the driving of the paper feeding unit by the second control unit within the predetermined time, the driving of the paper feeding unit is stopped. The paper feeding and conveying device according to claim 3, characterized in that.

9. The paper feeding and conveying device according to any one of claims 1 to 8, An image forming unit that forms an image on the recording medium fed and conveyed by the paper feeding and conveying device, An image forming apparatus characterized by comprising.

10. A method for determining the paper feeding performance of a paper feeding and conveying device, comprising a paper feeding unit that feeds a recording medium stacked on a paper feeding tray, a driving unit that drives the paper feeding unit, and a first detection unit that detects a current applied to the driving unit. A paper feeding performance determination method including a determination step of determining the paper feeding performance of the paper feeding unit based on the detection result of the first detection unit while the paper feeding unit is feeding the recording medium.

11. A computer of a paper feeding and conveying device, comprising a paper feeding unit that feeds a recording medium stacked on a paper feeding tray, a driving unit that drives the paper feeding unit, and a first detection unit that detects a current applied to the driving unit. A program for causing the computer to function as a determination unit that determines the paper feeding performance of the paper feeding unit based on the detection result of the first detection unit while the paper feeding unit is feeding the recording medium.

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