Paper feeding and conveying device, image forming apparatus, paper feeding performance recovery method, and program

Abstract

To provide a paper feeding and conveying device, an image forming apparatus, a paper feeding performance recovery method, and a program capable of recovering paper feeding performance of a paper feeding roller by detecting deterioration of the paper feeding performance of the paper feeding roller due to excessive paper powder on a surface of the paper feeding roller even in a state where paper is loaded on a paper feeding tray.SOLUTION: An image forming apparatus includes: a sheet feeding unit (sheet feeding roller 22) that feeds a recording medium loaded on a sheet feeding tray 21; a driving unit (motor 25) that drives the sheet feeding unit; a first detection unit (current detection unit 30) that detects current applied to the driving unit; a determination unit (control unit 11) that determines sheet feeding performance of the sheet feeding unit based on a detection result by the first detection unit; a first control unit (control unit 11) that presses and separates the recording medium against and from the sheet feeding unit; and a second control unit (control unit 11) that drives the sheet feeding unit by the driving unit after separating the recording medium from the sheet feeding unit by the first control unit. The first control unit separates the recording medium from the sheet feeding unit based on a determination result by the determination unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a paper feed conveying device, an image forming apparatus, a paper feed performance recovery method, and a program. [Background technology]

[0002] Conventionally, image forming apparatuses have been known that include a paper feed conveying device that feeds and conveys paper (recording media) to an image forming unit. The paper feed conveying device includes a paper feed roller that conveys paper in a conveying direction, a separation roller that presses against the paper feed roller to form a nip portion and prevent double paper feeding.

[0003] Patent Document 1 discloses a configuration for cleaning the paper feed roller by rotating (idling) the paper feed roller when no paper is sandwiched in the nip portion. Specifically, the configuration described in Patent Document 1 causes the paper feed roller to idle when the number of times the paper feed tray has been emptied reaches a predetermined number. The configuration described in Patent Document 1 also sets the predetermined number to a value smaller than normal if the separation roller is not rotating properly during the idle rotation. This allows the paper feed roller to be cleaned more frequently. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-131282 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the configuration described in Patent Document 1 allows the paper feed tray to rotate idly when it is empty, so the paper feed roller cannot be cleaned when paper is loaded in the paper feed tray. Since a large number of sheets of paper are typically loaded in the paper feed tray, if the paper feed performance deteriorates before the tray is emptied, it is not possible to detect the deterioration in paper feed performance. Therefore, the configuration described in Patent Document 1 has the problem of being unable to maintain a good paper feed state.

[0006] The present invention aims to provide a paper feed conveying device, an image forming device, a paper feed performance recovery method, and a program that can detect a decrease in the paper feed performance of a paper feed roller due to excessive paper dust on the surface of the paper feed roller even when paper is loaded in the paper feed tray, and can restore the paper feed performance of the paper feed roller. [Means for solving the problem]

[0007] The invention described in claim 1 has been made to achieve the above object, In the paper feed conveying device, a paper feed unit that feeds recording media loaded in a paper feed tray; a drive unit that drives the paper feed unit; a first detection unit that detects a current applied to the drive unit; a determination unit that determines paper feeding performance of the paper feeding unit based on the detection result by the first detection unit; a first control unit that presses and separates the recording medium from the paper feed unit; a second control unit that causes the drive unit to drive the paper feed unit after the first control unit separates the recording medium from the paper feed unit; Equipped with The first control unit separates the recording medium from the paper feed unit based on the determination result by the determination unit.

[0008] The invention described in claim 2 is the paper feed and conveyance device described in claim 1, a second detection unit that detects whether the paper feed tray is open or closed; The first control unit presses the recording medium against the paper feed unit after the second detection unit detects that the paper feed tray is closed.

[0009] The invention described in claim 3 is the paper feed and conveyance device described in claim 1, The second control unit drives the paper feed unit for a predetermined time when the determining unit determines that the paper feed performance has decreased.

[0010] The invention described in claim 4 is the paper feed and conveyance device described in claim 1, The recording medium conveying apparatus is characterized in that a pickup roller for picking up the recording medium is provided upstream of the paper feed unit in the conveying direction of the recording medium.

[0011] The invention described in claim 5 is the paper feed and conveyance device described in claim 1, The determination unit is characterized in that it determines that the paper feeding performance has deteriorated when the fluctuation range of the current value detected by the first detection unit while the paper feeding unit is operating is equal to or greater than a first threshold value.

[0012] The invention described in claim 6 is the paper feed and conveyance device described in claim 3, a third detection unit that detects the recording medium, the third detection unit being located downstream of the paper feed unit in a conveyance direction of the recording medium; The second control unit is characterized in that, when the recording medium is detected by the third detection unit while the paper feed unit is being driven for the predetermined time, the second control unit stops driving the paper feed unit.

[0013] The invention described in claim 7 is the paper feed and conveyance device described in claim 1, The first control unit separates the recording medium from the paper feed unit when the determining unit determines that the paper feed performance has decreased.

[0014] The invention described in claim 8 is the paper feed and conveyance device described in claim 7, The first control unit separates the recording medium from the paper feed unit during a period when the recording medium is not being fed by the paper feed unit.

[0015] The invention described in claim 9 is the paper feed and conveyance device described in claim 8, The period during which the recording medium is not fed includes a period during which a warm-up operation is being performed.

[0016] The invention described in claim 10 is the paper feed and conveyance device described in claim 8, The period during which the recording medium is not being fed includes a period during which an image stabilization operation is being performed.

[0017] The invention described in claim 11 is the paper feed and conveyance device described in claim 8, a plurality of combinations of the paper feed tray and the paper feed unit are provided; The period during which the recording medium is not being fed includes a period during which a paper feed unit other than the paper feed unit whose paper feed performance has been determined to have deteriorated is performing a paper feed operation.

[0018] The invention described in claim 12 is the paper feed and conveyance device described in claim 8, The period during which the recording medium is not being fed includes a period during which a malfunction occurs other than in the paper feed unit in which the paper feed performance has been determined to have deteriorated and in the paper feed tray in which the recording medium to be fed by the paper feed unit is loaded.

[0019] The invention described in claim 13 is the paper feed and conveyance device described in claim 8, The period during which the recording medium is not fed includes nighttime.

[0020] The invention described in claim 14 is the paper feed and conveyance device described in claim 1, when the determining unit determines that the paper feeding performance has decreased, the second control unit stops driving the paper feeding unit after feeding the recording medium currently being fed by the paper feeding unit; The first control unit separates the recording medium from the paper feed unit after the second control unit stops driving the paper feed unit.

[0021] The invention described in claim 15 is the paper feed and conveyance device described in claim 5, The first threshold value is set in plural.

[0022] The invention described in claim 16 is the paper feed and conveyance device described in claim 15, The first threshold value includes a threshold value that separates the recording medium from the paper feed unit when a print job being fed by the paper feed unit is completed.

[0023] The invention described in claim 17 is the paper feed and conveyance device described in claim 15, The first threshold value includes a threshold value at which a print job being fed by the paper feed unit is temporarily suspended and the recording medium is separated from the paper feed unit.

[0024] The invention described in claim 18 is the paper feed and conveyance device described in claim 17, The cleaning device is characterized by comprising a third control unit that displays a notice on a display unit indicating that cleaning of the paper feed unit is in progress during the temporary suspension.

[0025] The invention described in claim 19 is the paper feed and conveyance device described in claim 1, The determining unit determines that the paper feeding performance has deteriorated when the current value detected by the first detecting unit while the paper feeding unit is in operation is equal to or less than a second threshold value.

[0026] The invention described in claim 20 is In the image forming apparatus, a paper feed and conveyance device according to any one of claims 1 to 19; an image forming unit that forms an image on the recording medium fed and conveyed by the paper feeding and conveying device; The present invention is characterized by comprising:

[0027] The invention described in claim 21 is A method for recovering paper feeding performance of a paper feed conveying device including a paper feed unit that feeds recording media loaded in a paper feed tray, a drive unit that drives the paper feed unit, and a first detection unit that detects a current applied to the drive unit, comprising: a determining step of determining paper feeding performance of the paper feeding unit based on the detection result by the first detection unit; a first control step of pressing the recording medium away from the paper feed unit; a second control step of driving the paper feed unit by the drive unit after the recording medium is separated from the paper feed unit in the first control step; Including, The first control step separates the recording medium from the paper feed unit based on the determination result in the determination step.

[0028] The invention described in claim 22 is a computer for a paper feed conveying device including a paper feed unit that feeds recording media loaded on a paper feed tray, a drive unit that drives the paper feed unit, and 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 by the first detection unit; a first control unit that presses and separates the recording medium from the paper feed unit; a second control unit that causes the drive unit to drive the paper feed unit after the first control unit separates the recording medium from the paper feed unit; and make it work, The first control unit is a program that separates the recording medium from the paper feed unit based on the determination result by the determination unit. [Effects of the Invention]

[0029] According to the present invention, even when paper is loaded in the paper feed tray, it is possible to detect a decrease in the paper feed performance of the paper feed roller due to excessive paper dust on the surface of the paper feed roller, and to restore the paper feed performance of the paper feed roller. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a front view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is a functional block diagram showing a control structure of the image forming apparatus according to the present embodiment. [Figure 3] FIG. 2 is a side view showing a schematic configuration of a paper feeding and conveying section. [Figure 4] 3A and 3B are diagrams illustrating an example of paper feeding and conveying by a paper feeding and conveying unit. [Figure 5] 6 is a flowchart illustrating an example of control of the image forming apparatus according to the present embodiment. [Figure 6] 10A and 10B are diagrams for explaining the paper feed performance determination of a paper feed roller. [Figure 7] 10A and 10B are diagrams illustrating an example of maintaining paper feed performance by cleaning the paper feed roller. [Figure 8] 10A and 10B are diagrams illustrating an example of paper feeding and conveying by a paper feeding and conveying section in Modification 1. [Figure 9] 10A and 10B are diagrams for explaining the paper feed performance determination of the paper feed roller in Modification 1. FIG. [Figure 10] 10A and 10B are diagrams illustrating an example of maintaining paper feed performance by cleaning the paper feed roller in Modification 1. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0032] 1 and 2, the image forming apparatus 1 according to this 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 feed conveying unit 20. The paper feed conveying device of the present invention includes at least the control unit 11 and the paper feed conveying unit 20.

[0033] The control unit 11 includes a CPU, RAM, ROM, etc. The CPU first reads out various processing programs stored in the ROM in response to various signals and loads them into 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 loaded into the RAM.

[0034] The image reading unit 12 first scans and exposes an image of a document placed on a document table or an automatic document feeder (ADF) using the optical system of a scanning exposure device. Next, the image reading unit 12 reads the reflected light using a line image sensor to obtain an image signal. This image signal undergoes A / D conversion, shading correction, compression, and other processes before being input to the control unit 11 as image data. 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 that received from an external device (not shown) via the communication unit 16.

[0035] The image forming unit 13 forms an image made up of four colors, C, M, Y, and K, on ​​paper in accordance with 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 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.

[0036] The four writing units 131 are arranged in series (tandem) along the belt surface of the intermediate transfer belt 132 and form images of the respective colors of C, M, Y, and K. Each writing unit 131 includes an exposure unit 131a, a photoconductor 131b, a development unit 131c, a charging unit 131d, a cleaning unit 131e, and a primary transfer roller 131f. The writing units 131 have the same configuration, except that the colors of the images they form are different.

[0037] When forming an image, each writing unit 131 charges the photoconductor 131b using the charging unit 131d. Then, the exposure unit 131a scans the photoconductor 131b with a light beam emitted based on the original image, forming an electrostatic latent image on the photoconductor 131b. Next, the development unit 131c supplies a color material such as toner to the electrostatic latent image formed on the photoconductor 131b to develop it. In this way, the image forming unit 13 forms an image (toner image) on the photoconductor 131b. Next, each primary transfer roller 131f sequentially superimposes and primarily transfers the images formed on the photosensitive member 131b onto the intermediate transfer belt 132. As a result, an image made up of each color is formed on the intermediate transfer belt 132. The intermediate transfer belt 132 is an image carrier that rotates while being wound around multiple rollers. After the primary transfer, the cleaning unit 131e removes coloring material remaining on the photosensitive member 131b.

[0038] Paper is fed into the image forming unit 13 from the manual feed tray T1 or the paper feed conveyance unit 20 in time with the image on the rotating intermediate transfer belt 132 reaching the position of the secondary transfer roller 133. The secondary transfer roller 133 is one of a pair of rollers, one of which is in pressure contact with the intermediate transfer belt 132 and the other of which is wound around the intermediate transfer belt 132. The secondary transfer roller 133 performs a second transfer of 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 in which the fixing roller 134a heats and presses the paper to fix the image to the paper. The paper that has been fixed by the fixing unit 134 is discharged to the paper discharge tray T2 by the paper discharge roller R1. When forming images on both sides of the paper, the reversing path 135 reverses the paper surface of the transported paper, and then feeds the paper again to the position of the secondary transfer roller 133 .

[0039] The storage unit 14 is a non-volatile storage means configured by an HDD (Hard Disk Drive), an SSD (Solid State Drive), etc. The storage unit 14 stores various programs, various setting data, etc. in a manner that allows the control unit 11 to read and write data.

[0040] The operation panel 15 includes a display unit 151 that displays various information to the user, and an operation unit 152 that accepts operation inputs from the user. The display unit 151 is configured with a color liquid crystal display, etc. The display unit 151 displays operation screens, etc. (various setting screens, various buttons, operation status of each function, etc.) in accordance with a 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 with a finger, a touch pen, or the like, the operation unit 152 first detects the X and Y coordinates of the pressed point of force as a voltage value. 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. Furthermore, 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 make settings related to image formation, issue paper transport instructions, stop the device, and the like. The image formation settings include image quality settings, magnification settings, application settings, output settings, and paper settings.

[0041] The communication unit 16 is an interface that connects the image forming apparatus 1 to a communication network. The communication unit 16 includes a communication IC and a communication connector. Under the control of the control unit 11, the communication unit 16 transmits and receives various information to and from external devices connected to the communication network using a predetermined communication protocol. The communication unit 16 can also input and output various information via USB.

[0042] As shown in Fig. 1, a plurality of paper feed conveying units 20 are provided. Each paper feed conveying unit 20 supplies paper P toward the image forming unit 13. As shown in Figs. 2 and 3, each paper feed 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 lift 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.

[0043] The paper feed tray 21 stores paper sheets P of a predetermined paper type and size. The paper feed tray 21 is configured to be insertable and removable.

[0044] The paper feed roller (paper feed section) 22 feeds the paper sheets (recording media) P stacked in the paper feed tray 21. The paper feed roller 22 is installed on the leading edge side in the transport direction of the paper sheets P stacked on the lift plate 26. The paper feed roller 22 rotates counterclockwise along the transport direction of the paper sheets P while in contact with the top surface of the paper sheets P. In this way, the paper feed roller 22 feeds the paper sheets P in the transport direction.

[0045] The separation roller 23 is installed so as to form a nip portion between itself and 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 transport direction of the paper P (indicated by the symbol X in FIG. 4). When no sheet of paper P is sandwiched in the nip portion, the separation roller 23 rotates clockwise along the transport direction of the paper P. On the other hand, when multiple sheets of paper P are sandwiched in the nip portion, the separation roller 23 separates the lowermost sheet P2 from the uppermost sheet P1 (see FIG. 4). As a result, only the uppermost sheet P1 is fed in the transport direction in accordance with the rotation of the paper feed roller 22. Specifically, the separation roller 23 rotates counterclockwise in the opposite direction to the transport direction of the paper P. As a result, the lowermost sheet P2 is transported in the opposite direction to the transport direction in accordance with the rotation of the separation roller 23.

[0046] A torque limiter 231 is provided on the shaft of the separation roller 23. The driving force of the motor 25 is transmitted to and cut off from the separation roller 23 via the torque limiter 231. The torque limiter 231 is configured so that when a rotational load exceeding a predetermined value is applied to the separation roller 23, the separation roller 23 rotates idly relative to the torque limiter 231. Specifically, the torque limiter 231 cuts off the transmission of drive power from the motor 25 to the separation roller 23 when one sheet of paper P is sandwiched in the nip portion and when no sheet of paper P is sandwiched in the nip portion. This is because the rotational load on the separation roller 23 becomes relatively large. At this time, the separation roller 23 is in a state of idling relative to the torque limiter 231. As a result, the separation roller 23 rotates clockwise in conjunction with the rotation of the paper feed roller 22 (a driven rotation). On the other hand, when multiple sheets of paper P are sandwiched in the nip portion, torque limiter 231 transmits drive from motor 25 to separation roller 23. This is because the rotational load on separation roller 23 is relatively small due to slippage between sheets of paper P. As a result, separation roller 23 is driven to rotate counterclockwise. Therefore, of the multiple sheets of paper P sandwiched in the nip portion, the lower sheet P2, excluding the uppermost sheet P1, is transported in the opposite direction to the transport direction and returned to lift plate 26. With the above configuration, only one sheet of paper P is sent out in the transport direction from the nip between the paper feed roller 22 and the separation roller 23 without multiple sheets of paper P being fed.

[0047] The pickup roller 24 is disposed upstream of the paper feed roller 22 in the transport 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 transport direction of the paper P while in contact with the upper surface of the paper P stacked on the lift plate 26. In this way, the pickup roller 24 transports the paper P toward the position of the paper feed roller 22.

[0048] The motor (drive unit) 25 functions as a drive source that rotates and drives the paper feed roller 22, separation roller 23, and pickup roller 24. The motor 25 is feedback-controlled so that the rotation speed of the shaft is a predetermined value. Specifically, the control unit 11 adjusts the applied current by PWM control so that the rotation speed of the motor 25 is constant regardless of load fluctuations. For example, when the load on the motor 25 is large, the control unit 11 adjusts the applied current to be large. On the other hand, when the load on the motor 25 is small, the control unit 11 adjusts the applied current to be small. This keeps the rotation speed of the motor 25 constant. This enables stable paper feeding by the paper feed conveyance unit 20.

[0049] The lift plate 26 is provided at the bottom of the paper feed tray 21. The lift plate 26 moves up and down so that the pickup roller 24 can come into contact with the topmost sheet of paper P stacked on the lift plate 26. The lift plate 26 is moved up and down by a lift-up motor 27. The lift plate 26 moves up and down depending on the number of sheets of paper P stacked on it. The lift plate 26 moves up and down to a position where the pickup roller 24 comes into contact with the topmost sheet of paper P stacked on the lift plate 26. This allows the paper P to be fed and transported.

[0050] The lift-up motor 27 is a drive source that raises and lowers the lift-up plate 26 in the vertical direction. The lift-up motor 27 rotates clockwise to raise the lift-up plate 26. The lift-up motor 27 rotates counterclockwise to lower the lift-up plate 26.

[0051] Upper limit sensor 28 detects that the topmost sheet P stacked on lift plate 26 has reached its upper limit. That is, upper limit sensor 28 detects that pickup roller 24 is in contact with the top surface of the topmost sheet P stacked on lift plate 26. When upper limit sensor 28 detects that the topmost sheet P has reached its upper limit, pickup roller 24 begins to rotate counterclockwise. This causes the topmost sheet P stacked on lift plate 26 to be transported toward the nip portion between paper feed roller 22 and separation roller 23. Furthermore, paper feed roller 22 and separation roller 23 also begin to rotate at the same time as pickup roller 24 is rotated. This causes one sheet of paper P to be separated from the nip portion between paper feed roller 22 and separation roller 23 and transported toward image forming unit 13.

[0052] The lower limit sensor 29 detects when the lift plate 26 reaches the lower limit.

[0053] The current detection unit 30 detects the current applied to the motor 25. That is, the current detection unit 30 functions as a first detection unit of the present invention. The current detection unit 30 detects changes in the load torque applied to the motor 25 by detecting changes in the current applied to the motor 25. As the current detection unit 30, for example, a current measuring device that detects changes in the current applied to the motor 25 can be used.

[0054] The open / close detection unit 31 detects whether the paper feed tray 21 is open or closed. That is, the open / close detection unit 31 functions as a second detection unit of the present invention. The open / close detection unit 31 outputs detected information (that the paper feed tray 21 has been opened or closed) to the control unit 11. After the open / close detection unit 31 detects that the paper feed tray 21 has been closed, the control unit 11 presses the paper P against the paper feed roller 22.

[0055] Furthermore, a paper feed sensor SE1 is provided downstream of the paper feed conveyance unit 20 in the conveyance direction of the paper P. The paper feed sensor SE1 is, for example, an optical sensor that optically detects the paper P passing by. In other words, the paper feed sensor SE1 functions as a third detection unit of the present invention.

[0056] Next, the control of the image forming apparatus 1 according to this embodiment will be described with reference to the flowchart of Fig. 5. The control of Fig. 5 is started when the image forming apparatus 1 is powered on.

[0057] First, the control unit 11 determines the paper feed performance of the paper feed roller 22 (step S101). Specifically, the control unit 11 determines the paper feed performance based on the fluctuation range (PP) of the current value detected by the current detection unit 30. That is, the control unit 11 functions as a determination unit of the present invention that determines the paper feed performance of the paper feed roller 22 based on the detection result by the current detection unit 30.

[0058] Generally, the greater the amount of paper dust on the surface of the paper feed roller 22, the lower the paper feed performance of the paper feed roller 22. Therefore, the load on the pickup roller 24 increases. Because the surface of the pickup roller 24 is uneven, the load on the pickup roller 24 appears as a periodic component in the torque current of the motor 25. In other words, the greater the load on the pickup roller 24 due to an increase in the amount of paper dust on the surface of the paper feed roller 22, the larger the periodic component of the torque current. This increases the fluctuation range (PP) of the torque current of the motor 25. Therefore, the paper feed performance of the paper feed roller 22 can be determined by referring to the PP of the torque current of the motor 25.

[0059] FIG. 6 is a diagram for explaining the paper feed performance determination of the paper feed roller 22. FIG. 6(A) is a diagram showing an example of the torque current value of the motor 25 during paper feed. FIG. 6(B) is an enlarged view of a portion (the range indicated by the symbol G) of FIG. 6(A). FIG. 6(C) is a diagram showing the maximum, minimum, PP, and average value of the torque current in FIG. 6(A). In FIG. 6, the diagram on the left is a diagram showing a case where there is no paper dust. The diagram in the center is a diagram showing a case where there is a small amount of paper dust. The diagram on the right is a diagram showing a case where there is a large amount of paper dust (a situation where paper feed jams occur frequently). The symbol H in FIG. 6(B) indicates the PP of the torque current of the motor 25. 6, it can be seen that the PP value increases as the amount of paper dust increases. That is, by referring to the PP of the torque current of the motor 25, the paper feeding performance of the paper feed roller 22 can be determined. Specifically, when the fluctuation range (PP) of the current value detected by the current detection unit 30 while the paper feed roller 22 is being driven is equal to or greater than a first threshold value, the control unit 11 determines that the paper feed performance of the paper feed roller 22 has deteriorated. The first threshold value is a value smaller than the fluctuation range of the paper feed performance limit at which paper feed becomes impossible. In other words, the first threshold value is a value for determining the state immediately before the paper feed performance limit is reached.

[0060] 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 feed 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: NO), the process proceeds to step S101.

[0061] In step S103, the control unit 11 determines whether the lift plate 26 is rising (lifted up). That is, the control unit 11 determines whether the lift plate 26 is lifted up and the paper feed roller 22 can feed paper. When the control unit 11 determines that the lift plate 26 is being lifted up (step S103: YES), the process proceeds to the next step S104. On the other hand, when the control unit 11 determines that the lift plate 26 is not being lifted up (step S103: NO), the process proceeds to step S106.

[0062] In step S104, the control unit 11 determines whether or not paper is being fed by the paper feed roller 22. That is, the control unit 11 determines whether or not the paper P is being fed by the paper feed roller 22. When the control unit 11 determines that the paper feed rollers 22 are feeding paper (step S104: YES), the control unit 11 waits until the paper feed is completed. That is, the control unit 11 stops the driving of the paper feed rollers 22 after the paper P currently being fed by the paper feed rollers 22 is fed. On the other hand, if the control unit 11 determines that the paper feed roller 22 is not feeding paper (step S104: NO), it determines that the paper feed roller 22 is not feeding paper P, and proceeds to the next step S105.

[0063] In step S105, control unit 11 performs a process of lowering (lifting down) lift plate 26. Specifically, control unit 11 controls lift-up motor 27 to lift down lift plate 26. This causes paper P to separate from paper feed roller 22. That is, control unit 11 separates paper P from paper feed roller 22 based on the results of the paper feed performance determination. Specifically, control unit 11 separates paper P from paper feed roller 22 when it determines that paper feed performance has decreased. Furthermore, control unit 11 separates paper P from paper feed roller 22 during a period when paper P is not being fed by paper feed roller 22.

[0064] The period during which the paper P is not fed includes, for example, during a warm-up operation, during an image stabilization operation, and at night. Furthermore, the period during which the paper P is not being fed includes the period during which the paper feed rollers 22 other than the paper feed roller 22 determined to have a reduced paper feed performance are performing the paper feed operation. In addition, the period during which paper P is not being fed includes periods during which a malfunction occurs other than the paper feed roller 22 whose paper feeding performance has been determined to have deteriorated and the paper feed tray 21 that holds the paper P to be fed by the paper feed roller 22.

[0065] As described above, when it is determined that the paper feeding performance has deteriorated, the control unit 11 causes the paper P currently being fed by the paper feed roller 22 to be fed, and then stops the driving of the paper feed roller 22. Then, after the driving of the paper feed roller 22 has been stopped, the control unit 11 separates the paper P from the paper feed roller 22.

[0066] In step S106, the control unit 11 starts driving (rotating) the paper feed roller 22. Specifically, if the control unit 11 determines that the lift plate 26 is not being lifted up (step S103: NO), it starts driving the paper feed roller 22. On the other hand, if the control unit 11 determines that the lift plate 26 is being lifted up (step S103: YES), it starts driving the paper feed roller 22 after separating the paper P from the paper feed roller 22. That is, the control unit 11 functions as a second control unit of the present invention that drives the paper feed roller 22 by the motor 25 after separating the paper P from the paper feed roller 22. If it determines that the paper feeding performance has deteriorated, the control unit 11 drives the paper feed roller 22 for a predetermined time. In step S106, because the paper P is separated from the paper feed roller 22, the paper feed roller 22 rotates idly. This allows paper dust adhering to the surface of the paper feed roller 22 to fly off. This allows the paper feed roller 22 to be cleaned.

[0067] Next, the control unit 11 determines whether a predetermined time has elapsed since the start of driving the paper feed roller 22 (step S107). The predetermined time is the time required for 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), the process proceeds to step S109. On the other hand, if the control unit 11 determines that the predetermined time has not elapsed (step S107: NO), the process proceeds to the next step S108.

[0068] In step S108, the control unit 11 determines whether or not the paper feed sensor SE1 has detected the paper P. That is, the control unit 11 determines whether or not the topmost paper P has been unintentionally fed due to the driving (idle rotation) of the paper feed roller 22. When the control section 11 determines that the paper P has been detected (step S108: YES), the process proceeds to the next step S109. On the other hand, when the control section 11 determines that the paper P is not detected (step S108: NO), the process proceeds to step S107.

[0069] In step S109, the control unit 11 stops the driving (idle rotation) of the paper feed roller 22. That is, when a predetermined time has elapsed since the start of driving of the paper feed roller 22, the control unit 11 stops the driving of the paper feed roller 22. Furthermore, when the paper feed sensor SE1 detects a sheet of paper P while the paper feed roller 22 has been driven for the predetermined time, the control unit 11 stops the driving of the paper feed roller 22.

[0070] Next, the control unit 11 determines whether or not it has been determined in step S103 that the lift plate 26 is being lifted up (step S110). When the control unit 11 determines in step S103 that the lift plate 26 is being lifted up (step S110: YES), the process proceeds to the next step S111. On the other hand, when the control unit 11 determines in step S103 that the lift plate 26 is not being lifted up (step S110: NO), the process ends immediately.

[0071] Next, the control unit 11 controls the lift-up motor 27 to raise (lift up) the lift plate 26 (step S111). As a result, the control unit 11 presses the paper P against the paper feed roller 22. That is, the control unit 11 functions as a first control unit of the present invention that presses the paper P against and separates the paper feed roller 22.

[0072] Next, the control unit 11 causes the paper feed conveyance unit 20 to resume paper feeding (step S112).

[0073] In step S102, the control unit 11 determines whether the fluctuation range of the current value has reached a first threshold value. There may be a plurality of first threshold values. The first threshold value includes, for example, a threshold value at which the paper P is separated from the paper feed roller 22 when the print job currently being fed by the paper feed roller 22 is completed. The first threshold value also includes a threshold value at which the print job currently being fed by the paper feed roller 22 is temporarily interrupted and the paper P is separated from the paper feed roller 22. The threshold value for separating the printer when a print job is completed is a smaller value than the threshold value for temporarily suspending the print job to separate the printer. In situations where there is a margin up to the conveying performance limit, it is possible to wait until the print job is completed. On the other hand, in situations where there is not a margin up to the conveying performance limit, it is not possible to wait until the print job is completed. If the threshold value is set small, there is a margin up to the conveying performance limit, and it is possible to wait until the print job is completed. If the threshold value is set large, there is not a margin up to the conveying performance limit, and it is not possible to wait until the print job is completed. Therefore, the threshold value for separating the printer when a print job is completed is a smaller value than the threshold value for temporarily suspending the print job to separate the printer.

[0074] Note that, when the print job is temporarily suspended, the control unit 11 may display a notice on the display unit 151 indicating that the paper feed roller 22 is being cleaned. In this case, the control unit 11 functions as a third control unit of the present invention.

[0075] Fig. 7 shows an example of maintaining paper feed performance by cleaning paper feed roller 22. The horizontal axis of Fig. 7 represents time, and the vertical axis represents the value of torque current of motor 25. In Fig. 7, symbol JL1 represents the paper feed performance limit value, and symbol J1 represents the first threshold value. As explained with reference to FIG. 6 , the torque current PP of the motor 25 increases as the paper feed performance of the paper feed roller 22 deteriorates. The control unit 11 determines whether the lift plate 26 is lifted up when the fluctuation range (PP) of the current value detected by the current detection unit 30 reaches the first threshold J1 (see symbol N1). If the control unit 11 determines that the lift plate 26 is lifted up, it determines whether the paper feed roller 22 is currently feeding paper. If the control unit 11 determines that paper feed is currently in progress, the control unit 11 stops the drive of the paper feed roller 22 after feeding the paper P currently being fed by the paper feed roller 22. The control unit 11 lowers the lift plate 26 when paper feed is not in progress. This prevents the paper P from contacting the pickup roller 24. The control unit 11 idly rotates the paper feed roller 22 while the lift plate 26 is lifted down. This removes paper dust from the surface of the paper feed roller 22, which can cause paper feed performance to deteriorate. Then, when the idling of the paper feed roller 22 is completed, the control unit 11 raises (lifts up) the lifting plate 26. Thereafter, paper feed is started as usual, and the control unit 11 continues to monitor the torque current of the motor 25. In the example shown in FIG. 7, it can be seen that the fluctuation range of the torque current of the motor 25 becomes smaller after the paper feed roller 22 has idled (see symbol N2). In other words, it can be seen that the paper feed performance of the paper feed roller 22 has recovered.

[0076] When there is a large amount of paper P stacked in the paper feed tray 21, the paper P may come into contact with the pickup roller 24 even without lifting up the lifting plate 26. If the paper feed roller 22 is attempted to rotate idly in this state, the topmost paper P will be fed. Therefore, the paper feed sensor SE1 is monitored while the paper feed roller 22 is rotating idly. If the paper feed sensor SE1 detects a paper P, the control unit 11 stops the idling of the paper feed roller 22. This makes it possible to prevent the topmost paper P from being fed while the paper feed roller 22 is rotating idly.

[0077] As described above, the image forming apparatus 1 according to this embodiment includes a paper feed unit, a drive unit, a first detection unit, a determination unit, a first control unit, and a second control unit. The paper feed unit (paper feed roller 22) feeds recording media (paper sheets P) loaded in 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. The first control unit (control unit 11) presses the recording medium away from the paper feed unit. The second control unit (control unit 11) causes the first control unit to separate the recording medium from the paper feed unit, and then causes the drive unit to drive the paper feed unit. The first control unit separates the recording medium from the paper feed unit based on the determination result by the determination unit. Therefore, with the image forming apparatus 1 according to this embodiment, even when paper is stacked in the paper feed tray 21, it is possible to detect a decrease in the paper feed performance of the paper feed unit due to an excess of paper dust on the surface of the paper feed unit. When a decrease in paper feed performance is detected, the paper feed unit can be made to idle. This causes the paper dust adhering to the surface of the paper feed unit to fly off, cleaning the paper feed unit. This allows the paper feed performance of the paper feed unit to be restored.

[0078] The device also includes a second detection unit (open / close detection unit 31) that detects the opening and closing of the paper feed tray 21. After the second detection unit detects that the paper feed tray 21 is closed, the first control unit presses the recording medium against the paper feed unit. Therefore, when the paper feed tray 21 is closed, it is possible to automatically prepare for the paper feed unit to resume paper feeding, so that paper feeding by the paper feed unit can be resumed without any trouble to the user.

[0079] Furthermore, the second control unit drives the paper feed unit for a predetermined time when the determining unit determines that the paper feed performance has decreased. Therefore, when a decrease in paper feeding performance is detected, the paper feeding unit can be rotated idly, which causes paper dust adhering to the surface of the paper feeding unit to fly off and clean the paper feeding unit, thereby restoring the paper feeding performance of the paper feeding unit.

[0080] Further, a pickup roller 24 for picking up the recording medium is provided upstream of the paper feed unit in the recording medium transport direction. Therefore, the paper feed roller 22 can smoothly feed the paper.

[0081] Furthermore, the determining unit determines that the paper feeding performance has deteriorated when the fluctuation range of the current value detected by the first detecting unit while the paper feeding unit is being driven is equal to or greater than a first threshold value. Therefore, it is possible to determine whether the paper feeding performance has deteriorated even when paper is stacked in the paper feed tray 21. As a result, a good paper feeding state can be maintained.

[0082] In addition, a third detection unit (paper feed sensor SE1) that detects the recording medium is provided downstream of the paper feed unit in the recording medium transport direction. The second control unit stops driving the paper feed unit when the third detection unit detects the recording medium while the paper feed unit is being driven for a predetermined time. Therefore, it is possible to prevent the topmost sheet P from being fed while the idle rotation is being performed, thereby preventing unintended sheet feeding by the user.

[0083] Furthermore, the first control unit separates the recording medium from the paper feed unit when the determining unit determines that the paper feed performance has decreased. Therefore, when a decrease in paper feeding performance is detected, the paper feeding unit can be rotated idly, which causes paper dust adhering to the surface of the paper feeding unit to fly off and clean the paper feeding unit, thereby restoring the paper feeding performance of the paper feeding unit.

[0084] The first control unit also separates the recording medium from the paper feed unit during a period when the recording medium is not being fed by the paper feed unit. The period when the recording medium is not being fed includes during a warm-up operation, during an image stabilization operation, and at night. The period when the recording medium is not being fed also includes during a paper feeding operation by a paper feed unit other than the paper feed unit determined to have a reduced paper feeding performance. The period when the recording medium is not being fed also includes during a malfunction other than the paper feed unit determined to have a reduced paper feeding performance and the paper feed tray 21 containing the recording medium fed by that paper feed unit. Therefore, the paper feed unit can be idled during the period when no paper is being fed, and the paper feed performance of the paper feed unit can be restored without reducing the productivity of the apparatus.

[0085] Furthermore, when the determining unit determines that the paper feeding performance has deteriorated, the second control unit stops driving the paper feeding unit after feeding the recording medium currently being fed by the paper feeding unit. After the second control unit stops driving the paper feeding unit, the first control unit moves the recording medium away from the paper feeding unit. Therefore, an image can be formed without damaging the recording medium during feeding, thereby suppressing the occurrence of image defects.

[0086] The printer also has a plurality of first thresholds, including a threshold at which the recording medium is separated from the paper feed unit when the print job currently being fed by the paper feed unit is completed, and a threshold at which the print job currently being fed by the paper feed unit is temporarily interrupted and the recording medium is separated from the paper feed unit. Therefore, the paper feeding performance of the paper feeding section can be restored while ensuring the productivity of the apparatus.

[0087] The apparatus also includes a third control unit (control unit 11) that, when the operation is temporarily suspended, displays on display unit 151 a notice indicating that the paper feed unit is being cleaned. Therefore, the user can be notified of the reason for the temporary suspension, and the user can operate the device without becoming suspicious.

[0088] Although the present invention has been specifically described above based on the embodiments thereof, the present invention is not limited to the above embodiments and can be modified within the scope of the present invention.

[0089] (Variation 1) For example, in the above embodiment, the paper feed conveying unit 20 is described as having the pickup roller 24, but the present invention is not limited to this. For example, as shown in FIG. 8, the paper feed conveying unit 20A may not have the pickup roller 24.

[0090] 9A and 9B are diagrams for explaining the paper feeding performance determination of paper feed roller 22 in Modification 1. FIG. 9A is a diagram showing an example of the value of torque current of motor 25 during paper feeding. FIG. 9B is a diagram showing the average value of torque current in FIG. 9A. In FIG. 9, the diagram on the left is a diagram showing a case where there is no paper dust. The diagram in the middle is a diagram showing a case where there is a small amount of paper dust. The diagram on the right is a diagram showing a case where there is a large amount of paper dust (a situation where paper feed jams occur frequently). Generally, the greater the amount of paper dust on the surface of the paper feed roller 22, the lower the paper feed performance of the paper feed roller 22. Therefore, the load on the paper feed roller 22 decreases. This reduces the average value of the torque current of the motor 25. In the example shown in FIG. 9, it can be seen that the average value decreases as the amount of paper dust increases. Therefore, the paper feed performance of the paper feed roller 22 can be determined by referring to the average value of the torque current of the motor 25. Specifically, when the current value detected by current detection unit 30 while paper feed roller 22 is being driven is equal to or less than the second threshold value, control unit 11 determines that the paper feed performance of paper feed roller 22 has deteriorated. The second threshold value is a value greater than the paper feed performance limit at which paper feed becomes impossible. In other words, the second threshold value is a value for determining the state immediately before the paper feed performance limit is reached.

[0091] Fig. 10 shows an example of maintaining paper feed performance by cleaning paper feed roller 22 in Modification 1. The horizontal axis of Fig. 10 represents time, and the vertical axis represents the average value of the torque current of motor 25. In Fig. 10, symbol JL2 represents the paper feed performance limit value, symbol J2 represents the second threshold value, and symbol J0 represents the normal value. As described with reference to FIG. 9 , the average torque current of the motor 25 decreases as the paper feed performance of the paper feed roller 22 deteriorates. The control unit 11 determines whether the lift plate 26 is lifted up when the average current value detected by the current detection unit 30 reaches the second threshold J2 (see symbol N3). If the control unit 11 determines that the lift plate 26 is lifted up, it determines whether the paper feed roller 22 is currently feeding paper. If the control unit 11 determines that paper feed is currently in progress, the control unit 11 stops the drive of the paper feed roller 22 after feeding the paper P currently being fed by the paper feed roller 22. The control unit 11 lowers the lift plate 26 when paper feed is not in progress. This prevents the paper P from contacting the paper feed roller 22. The control unit 11 idly rotates the paper feed roller 22 while the lift plate 26 is lifted down. This removes paper dust from the surface of the paper feed roller 22, which can cause paper feed performance to deteriorate. Then, when the idling of the paper feed roller 22 is completed, the control unit 11 raises (lifts up) the lifting plate 26. Thereafter, paper feed is started as usual, and the control unit 11 continues to monitor the average value of the torque current of the motor 25. In the example shown in FIG. 10, after the idling of the paper feed roller 22 (see symbol N4), it can be seen that the average value of the torque current of the motor 25 has returned to the normal value J0. In other words, it can be seen that the paper feed performance of the paper feed roller 22 has recovered.

[0092] In the first modification, the control unit 11 determines that the paper feed performance has deteriorated when the current value detected by the current detection unit 30 while the paper feed roller 22 is being driven is equal to or less than the second threshold value. Therefore, it is possible to determine whether the paper feeding performance has deteriorated even when paper is stacked in the paper feed tray 21. As a result, a good paper feeding state can be maintained.

[0093] Here, similar to the first threshold, there may be a plurality of second thresholds. The second threshold value includes, for example, a threshold value at which the paper P is separated from the paper feed roller 22 when the print job currently being fed by the paper feed roller 22 is completed. The second threshold value also includes a threshold value at which the print job currently being fed by the paper feed roller 22 is temporarily interrupted and the paper P is separated from the paper feed roller 22. The threshold value for separating the printer when a print job is completed is set to a value greater than the threshold value for temporarily suspending the print job to separate the printer. In situations where there is a margin up to the conveying performance limit, it is possible to wait until the print job is completed. On the other hand, in situations where there is not a margin up to the conveying performance limit, it is not possible to wait until the print job is completed. If the threshold value is set to a large value, there is a margin up to the conveying performance limit, and it is possible to wait until the print job is completed. If the threshold value is set to a small value, there is not a margin up to the conveying performance limit, and it is not possible to wait until the print job is completed. Therefore, the threshold value for separating the printer when a print job is completed is set to a value greater than the threshold value for temporarily suspending the print job to separate the printer.

[0094] Although the first modification has been described with reference to an example in which the paper feed conveying unit 20 does not include the pickup roller 24, the present invention is not limited to this. For example, the paper feed conveying unit 20 may include a pickup roller with a flat, non-convex surface. In the case of a configuration in which the pickup roller has a flat surface, the paper feed performance of the paper feed roller 22 can be determined by referring to the average value of the torque current of the motor 25, as in the configuration of the first modification.

[0095] (Other variations) Furthermore, in the above embodiment, if the paper feed sensor SE1 detects paper P before a predetermined time has elapsed since the start of the drive (idle rotation) of the paper feed roller 22, the drive of the paper feed roller 22 is stopped and normal paper feed operation is resumed, but this is not limited to this. For example, instead of returning to normal paper feed operation, the display unit 151 may display a message indicating that the cleaning (idle rotation) of the paper feed roller 22 has resulted in an error. In this case, since there is too much paper P loaded in 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.

[0096] Alternatively, instead of returning to normal paper feeding operation, the system may be left alone for a while (to feed paper P). In this case, after several sheets of paper P have been fed, the paper P will no longer be in contact with the pickup roller 24. By running the paper feed roller 22 idly in this state, the paper feed roller 22 can be cleaned. After that, when a predetermined time has elapsed since the paper P no longer came into contact with the pickup roller 24, the idly rotation is stopped, and normal paper feeding operation is resumed. The state in which the paper P no longer comes into contact with the pickup roller 24 can be estimated from the timing when the paper feed sensor SE1 no longer detects the paper P. This allows the paper feeding performance of the paper feed roller 22 to be restored.

[0097] In the above embodiment, the paper feed roller 22 is cleaned by rotating the paper feed roller 22 idly, but the present invention is not limited to this. For example, the paper feed roller 22 may be cleaned by contacting a cleaning member such as a brush with the paper feed roller 22.

[0098] In addition, the detailed configuration and operation of each device constituting the image forming apparatus can be modified as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0099] 1. Image forming device 11 control unit (determination unit, first control unit, second control unit, third control unit) 12 Image reading unit 13 Image forming unit 131 Writing section 131a Exposure section 131b Photoreceptor 131c Development section 131d Charging part 131e Cleaning Department 131f Primary transfer roller 132 Intermediate transfer belt 133 Secondary transfer roller 134 Fixing section 14 Storage section 15 Operation panel 151 Display section 152 Operation section 16 Communications Department 20 Paper feed transport section 21 Paper tray 22 Paper feed roller (paper feed section) 23 Separation roller 231 Torque limiter 24 Pickup roller 25 Motor (drive unit) 26 Lifting platform 27 Lift-up motor 28 Upper limit sensor 29 Lower limit sensor 30 Current detection unit (first detection unit) 31 Open / close detection unit (second detection unit) SE1 Paper feed sensor (third detection unit) P Paper (recording medium)

Claims

1. a paper feed unit that feeds recording media loaded in a paper feed tray; a drive unit that drives the paper feed unit; a first detection unit that detects a current applied to the drive unit; a determination unit that determines paper feeding performance of the paper feeding unit based on a detection result by the first detection unit; a first control unit that presses and separates the recording medium from the paper feed unit; a second control unit that causes the drive unit to drive the paper feed unit after the first control unit separates the recording medium from the paper feed unit; Equipped with The paper feed and transport device, wherein the first control unit separates the recording medium from the paper feed unit based on the determination result by the determination unit.

2. a second detection unit that detects whether the paper feed tray is open or closed; 2. The paper feed and transport device according to claim 1, wherein the first control unit presses the recording medium against the paper feed unit after the second detection unit detects that the paper feed tray is closed.

3. 2. The paper feed and transport device according to claim 1, wherein the second control unit drives the paper feed unit for a predetermined time when the determining unit determines that the paper feed performance has decreased.

4. 2. The paper feed and transport device according to claim 1, further comprising a pickup roller for picking up the recording medium, the pickup roller being disposed upstream of the paper feed unit in the transport direction of the recording medium.

5. The paper feed conveying device according to claim 1, characterized in that the judgment unit judges that the paper feed performance has deteriorated when the fluctuation range of the current value detected by the first detection unit during operation of the paper feed unit is greater than or equal to a first threshold value.

6. a third detection unit that detects the recording medium, the third detection unit being located downstream of the paper feed unit in a conveyance direction of the recording medium; The paper feed conveying device according to claim 3, characterized in that the second control unit stops driving the paper feed unit when the recording medium is detected by the third detection unit while the paper feed unit is being driven for the predetermined time.

7. 2. The paper feed and transport device according to claim 1, wherein the first control unit separates the recording medium from the paper feed unit when the determining unit determines that the paper feed performance has decreased.

8. 8. The paper feed and transport device according to claim 7, wherein the first control unit separates the recording medium from the paper feed unit during a period when the recording medium is not being fed by the paper feed unit.

9. 9. The paper feed and transport device according to claim 8, wherein the period during which the recording medium is not being fed includes a period during which a warm-up operation is being performed.

10. 9. The paper feed and transport device according to claim 8, wherein the period during which the recording medium is not being fed includes a period during which an image stabilization operation is being performed.

11. a plurality of combinations of the paper feed tray and the paper feed unit are provided; 9. The paper feed and transport device according to claim 8, wherein the period during which the recording medium is not being fed includes a period during which a paper feed unit other than the paper feed unit whose paper feed performance has been determined to have deteriorated is performing a paper feed operation.

12. The paper feed conveying device according to claim 8, characterized in that the period during which the recording medium is not being fed includes a period during which a malfunction occurs other than in the paper feed unit in which the paper feed performance has been determined to have deteriorated and in the paper feed tray in which the recording medium to be fed by the paper feed unit is loaded.

13. 9. The paper feed and transport device according to claim 8, wherein the period during which the recording medium is not fed includes nighttime.

14. when the determining unit determines that the paper feeding performance has decreased, the second control unit causes the paper feeding unit to feed the recording medium that is currently being fed, and then stops driving the paper feeding unit; 2. The paper feed and transport device according to claim 1, wherein the first control unit separates the recording medium from the paper feed unit after the second control unit stops driving the paper feed unit.

15. 6. The paper feed and transport device according to claim 5, wherein the first threshold value is set in plural.

16. 16. The paper feed and transport device according to claim 15, wherein the first threshold value includes a threshold value that separates the recording medium from the paper feed unit when a print job being fed by the paper feed unit is completed.

17. 16. The paper feed and transport device according to claim 15, wherein the first threshold value includes a threshold value that temporarily suspends a print job being fed by the paper feed unit and separates the recording medium from the paper feed unit.

18. 18. The paper feed and transport device according to claim 17, further comprising a third control unit that, during the temporary suspension, displays a notice on a display unit indicating that cleaning of the paper feed unit is in progress.

19. The paper feed conveying device according to claim 1, wherein the determination unit determines that the paper feed performance has deteriorated when the current value detected by the first detection unit while the paper feed unit is operating is equal to or less than a second threshold value.

20. a paper feed conveying device according to any one of claims 1 to 19; 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 comprising:

21. A method for recovering paper feeding performance of a paper feed conveying device including a paper feed unit that feeds recording media loaded in a paper feed tray, a drive unit that drives the paper feed unit, and a first detection unit that detects a current applied to the drive unit, a determining step of determining paper feeding performance of the paper feeding unit based on a detection result by the first detection unit; a first control step of pressing the recording medium away from the paper feed unit; a second control step of driving the paper feed unit by the drive unit after the recording medium is separated from the paper feed unit in the first control step; Including, The paper feeding performance recovery method is characterized in that the first control step separates the recording medium from the paper feeding unit based on the determination result in the determination step.

22. a computer for a paper feed conveying device including a paper feed unit that feeds recording media loaded on a paper feed tray, a drive unit that drives the paper feed unit, and 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 by the first detection unit; a first control unit that presses and separates the recording medium from the paper feed unit; a second control unit that causes the drive unit to drive the paper feed unit after the first control unit separates the recording medium from the paper feed unit; and make it work, The first control unit separates the recording medium from the paper feed unit based on the determination result by the determination unit.

Images