Sheet carrier device

Abstract

To provide a sheet carrier device that saves users unnecessary effort and can also protect sheets and documents.SOLUTION: A document feeder is arranged downstream in a document transport direction of a pickup roller and is equipped with a rear sensor that detects the presence or absence of a document. When the controller receives a paper feed command, it rotates the transport motor to perform the paper feeding operation, starts measurement with a timer from a predetermined timing, and if the rear sensor does not detect the document and the measured time by the timer exceeds a set time TL1, it determines that a paper feed failure has occurred. Based on the temperature indicated by the output from the temperature sensor, it decides whether or not to perform a re-feed operation of the document. According to such a document feeder, by performing the re-feed operation of the document according to various usage environments, it is possible to execute the re-feed operation when it is less likely to damage the document, thereby saving unnecessary effort of the user and protecting the document.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a sheet transport device that transports a sheet. [Background technology]

[0002] A paper feed unit or ADF (Auto Document Feeder) is configured to send the topmost sheet or document of a stack of sheets or documents placed on a paper feed tray or document tray to a transport path using a pickup roller, and has a control unit that determines whether the sheet or document will arrive by a predetermined time using a sensor that detects whether the leading edge of the sheet or document passes a predetermined position. If the control unit determines that the sheet or document is not being transported for some reason, it does not immediately generate a non-feed error, but instead performs a paper re-feed operation multiple times to prevent the device from stopping due to an insufficient transport amount caused by a simple slippage or the like, rather than an unrecoverable error such as a jam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5757858 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the control is such that a re-feed operation is always performed when the paper or document has not been transported by a predetermined amount, the paper or document will be re-fed and transported even when it cannot be detected within a predetermined time due to a jam, which may cause further damage to the paper or document.

[0005] The present invention has been made in view of such circumstances, and aims to provide a sheet conveying device that can save the user unnecessary trouble and protect the paper or document by performing a paper re-feed operation when it is unlikely to damage the paper or document. [Means for solving the problem]

[0006] In order to achieve the above object, the sheet conveying device of the present application comprises a pickup roller that feeds a sheet placed on a sheet placing surface, a motor that rotates the pickup roller, a sheet sensor that is arranged downstream of the pickup roller in the sheet conveying direction and whose output changes depending on the presence or absence of a sheet, a temperature sensor that detects air temperature, a timer, and a control unit, and when the control unit receives a paper feed command, it rotates the motor to perform a paper feed operation, starts timing by the timer from a predetermined timing, and determines that a sheet has not been fed if the timer's timing has exceeded a predetermined time without the sheet sensor outputting a signal corresponding to the presence of a sheet, and determines whether or not to perform a sheet re-feed operation based on the temperature detected by the temperature sensor. [Effects of the Invention]

[0007] According to the sheet conveying device of the present application having the above-described configuration, whether to perform a sheet refeed operation is determined based on the temperature. In a normal temperature environment, sheet non-feeding is almost always caused by a jam, and continuing to convey the document often results in significant damage. In contrast, in a low-temperature or high-temperature environment, sheet non-feeding is often caused by an increase in the conveying load or a decrease in the driving force of a motor, etc. Therefore, by performing a sheet refeed operation based on the temperature, the refeed operation can be performed when damage to the paper or document is unlikely to occur. This saves the user unnecessary effort and protects the paper and document. [Brief explanation of the drawings]

[0008] [Figure 1]1 is a side cross-sectional view showing a document feeder according to an embodiment of the present invention; [Figure 2] 10 is a side cross-sectional view of the main part of the document feeder in a state where the roller holder is swung downward. FIG. [Figure 3] 10 is a side cross-sectional view of the main part of the document feeder in a state where the roller holder is swung upward. FIG. [Figure 4] FIG. 2 is a perspective view showing a drive transmission mechanism that transmits a drive force to a separation roller and a pickup roller. [Figure 5] FIG. 2 is an exploded perspective view showing a drive transmission mechanism that transmits a drive force to a separation roller and a pickup roller. [Figure 6] FIG. 2 is an exploded perspective view showing a drive transmission mechanism that transmits a drive force to a separation roller and a pickup roller. [Figure 7] FIG. 2 is a block diagram showing the electrical configuration of the image reading device. [Figure 8] 10 is a flowchart of a paper feed operation process according to the embodiment. [Figure 9] 10 is a flowchart of a paper feed operation process according to the embodiment. [Figure 10] 10 is a flowchart of a paper feed operation process according to the embodiment. [Figure 11] 10 is a flowchart of a paper feed operation process according to the embodiment. [Figure 12] 10 is a flowchart of a paper feed operation process according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment in which a sheet transport device according to the present application is embodied in an ADF (Auto Document Feeder) of a scanner, which is an image forming apparatus, will be described below with reference to the drawings. FIG. 1 is a side cross-sectional view showing a document feeder 10 of this embodiment. Note that, although the following description will be directed to an embodiment in which the sheet transport device is embodied in a document feeder 10 of a scanner, the "sheet transport device" can be embodied not only in a document reading device such as a scanner, but also in a device that transports sheets, such as a printing device, a copier, a facsimile machine, or a multifunction device with a printer function and a scanner function. Furthermore, the term "sheet" is not limited to a paper document but also includes overhead projector sheets, film, and the like, as well as paper as a recording medium.

[0010] [Document feeder] The document feeder 10 (an example of a sheet conveying device) shown in FIG. 1 is attached to the image reading device 12 and feeds a document to be read onto a contact glass 14 arranged on the upper surface of the image reading device 12. A reading device 16 (an example of a reading unit) is provided below the contact glass 14. The reading device 16 incorporates a light source, an image sensor, and the like. The image sensor is, for example, a linear image sensor in which multiple light-receiving elements are arranged in the main scanning direction. The image reading device 12 also has a user I / F 18 (see FIG. 7) (an example of a display unit) for providing information to a user and accepting user operations. The user I / F 18 is, for example, a touch panel that also functions as a display.

[0011] The document feeder 10 includes a housing 20. The housing 20 is provided with a document tray 22 and a discharge tray 24. The document tray 22 and the discharge tray 24 are arranged in a vertically stacked state with a gap between them. A portion of each of the document tray 22 and the discharge tray 24 is disposed inside the housing 20, with the remaining portion exposed to the outside of the housing 20. The document tray 22 and the discharge tray 24 are each configured to be able to support a plurality of sheet-like documents in a stacked state. A tray sensor 28 is disposed on a document placement surface 22a (an example of a sheet placement surface) of the document tray 22 on which the documents are placed. The output of the tray sensor 28 changes depending on whether or not a document is placed on the document placement surface 22a. A height sensor 29 is disposed above the document placement surface 22a. The output of the height sensor 29 changes depending on the height of the documents placed on the document placement surface 22a. The height sensor 29 may be configured to measure the height of the document by physically placing an actuator on the top surface of the document placed on the document placing surface 22a, or may be configured to measure the height of the document by irradiating the top surface of the document placed on the document placing surface 22a with laser light to detect the height to the top surface of the document.

[0012] In document feeder 10, the side where document tray 22 and discharge tray 24 are provided is referred to as the "front side," and the opposite side is referred to as the "rear side." Furthermore, when viewing document feeder 10 from the front side, the right side (the back side of the paper) is referred to as the "right side," and the opposite side (the front side of the paper) is referred to as the "left side."

[0013] A temperature sensor 26 (see FIG. 7) is also disposed inside the housing 20 or the image reading device 12. The temperature sensor 26 is fixed to the inside of the right side wall of the housing 20 or the image reading device 12, and its output changes depending on the detected temperature. A slit (not shown) is formed in the right side wall of the housing 20 or the image reading device 12 near the temperature sensor 26. Therefore, although the temperature sensor 26 is disposed inside the housing 20 or the image reading device 12, outside air enters the inside of the housing 20 or the image reading device 12 through the slit, and therefore the temperature sensor 26 detects the environmental temperature of the environment in which the image reading device 12 is disposed, and its output changes depending on the environmental temperature, i.e., the air temperature.

[0014] A transport path 30 is formed inside the housing 20. One end of the transport path 30 opens toward the document tray 22, extends toward the opposite side of the document tray 22, curves downward while folding back, extends toward the discharge tray 24, and the other end opens toward the discharge tray 24. The transport path 30 passes over the contact glass 14 on the discharge tray 24 side of the curved folded back portion.

[0015] Along the conveying path 30, a pickup roller 32, a separation roller 34, a first conveying roller 36, a second conveying roller 38, and a paper discharge roller 40 are provided in this order from the document tray 22 side.

[0016] The pickup roller 32 and the separation roller 34 are arranged near the entrance of the transport path 30, side by side in the transport direction of the originals near the entrance. The pickup roller 32 and the separation roller 34 are rotatably held by a roller holder 50 (an example of a pickup arm). The roller holder 50 is supported so as to be swingable around the axis of the separation roller 34. As a result, when the roller holder 50 swings, the pickup roller 32 descends as shown in FIG. 2 and rises as shown in FIG. 3. When the pickup roller 32 descends due to the swing of the roller holder 50, it comes into contact with the upper surfaces of the originals placed on the original tray 22. At this time, when the pickup roller 32 rotates, the uppermost original in contact with the circumferential surface of the pickup roller 32 is sent toward the separation roller 34, and the original enters between the separation roller 34 and the separation pad 52 in contact with the circumferential surface of the separation roller 34. The originals that have entered between the separation roller 34 and the separation pad 52 are separated into individual sheets as they pass between the separation roller 34 and the separation pad 52, and then enter the conveying path 30. The originals that have entered the conveying path 30 are conveyed along the conveying path 30 by receiving conveying forces from the first conveying roller 36, the second conveying roller 38, and the paper discharge roller 40 in that order, and are then discharged onto the discharge tray 24 by the paper discharge roller 40.

[0017] The document passes over the contact glass 14 between the first conveyor roller 36 and the second conveyor roller 38. A rear sensor 56 (an example of a sheet sensor) is disposed between the first conveyor roller 36 and the contact glass 14, that is, downstream of the first conveyor roller 36 in the document conveyance direction and upstream of the contact glass 14. The output of the rear sensor 56 changes depending on whether a document is present. That is, the output changes depending on whether the document has passed downstream of the first conveyor roller 36 in the document conveyance direction and upstream of the contact glass 14. A paper discharge sensor 58 is disposed downstream of the paper discharge roller 40 in the document conveyance direction. The output of the paper discharge sensor 58 changes depending on whether a document is present. That is, the output changes depending on whether the document has passed downstream of the paper discharge roller 40 in the document conveyance direction. This makes it possible to detect whether the document has been discharged from the conveyance path 30, i.e., whether the document has been discharged onto the discharge tray 24.

[0018] Furthermore, after passing over the first transport roller 36, the original passes over the contact glass 14, and at this time, the image of the surface of the original that comes into contact with the contact glass 14 is read by the reading device 16 in the image reading device 12. That is, as the original passes over the contact glass 14, light from the light source of the reading device 16 is irradiated onto the surface of the original that is to be read and that is in contact with the contact glass 14. When the image sensor of the reading device 16 receives the light reflected from the surface to be read, the image sensor outputs an analog image signal for one line. As the original is transported, the image of the surface to be read is read line by line from the upstream end to the downstream end in the sub-scanning direction orthogonal to the main scanning direction, thereby achieving reading of the image of the surface to be read.

[0019] [Drive transmission mechanism] The pickup roller 32 and separation roller 34 are connected to a conveyance motor 60 (see FIG. 7) (an example of a motor) via a drive transmission mechanism 62 (an example of a drive transmission section) shown in FIGS. 4 to 6, and are rotated by the drive of the conveyance motor 60. The drive transmission mechanism 62 includes a transmission shaft 66, a torque limiter 68, a bearing 70, a gear train 72, a one-way clutch 74, and a one-way clutch 76.

[0020] The transmission shaft 66 is connected to the conveying motor 60 and rotates about its axis when driven by the conveying motor 60. The transmission shaft 66 is disposed inside the housing 20 in an orientation extending in the left-right direction. A torque limiter 68 is connected to the tip of the transmission shaft 66. The torque limiter 68 has an inner cylinder 68a and an outer cylinder 68b, with the inner cylinder 68a inserted inside the outer cylinder 68b. A transmission unit (not shown) is disposed between the inner cylinder 68a and the outer cylinder 68b. The transmission unit transmits the rotational force of the inner cylinder 68a to the outer cylinder 68b, but can only transmit driving forces less than a predetermined driving force. When a driving force greater than the predetermined driving force is input, the inner cylinder 68a rotates freely relative to the outer cylinder 68b. The tip of the transmission shaft 66 is coaxially fixed to the inner cylinder 68a. A bearing 70 is coaxially fixed to the outer cylinder 68b.

[0021] The pickup roller 32 is rotatably held by the roller holder 50 via a shaft 78, and rotates about the shaft 78 within the roller holder 50. The separation roller 34 is rotatably held by the roller holder 50 via a shaft 80, and rotates about the shaft 80 within the roller holder 50. The shaft 78 of the pickup roller 32 and the shaft 80 of the separation roller 34 are parallel to each other. A gear 72a is fixed to the shaft 78 of the pickup roller 32, and a gear 72b is fixed to the shaft 80 of the separation roller 34. The gear 72a on the shaft 78 of the pickup roller 32 and the gear 72b on the shaft 80 of the separation roller 34 are connected by two gears 72c and 72d. A through hole 82 is formed inside the bearing 70, and the shaft 80 of the separation roller 34 passes through the through hole 82 of the bearing 70 and the inside of the inner cylinder 68a of the torque limiter 68, and is coaxially fixed to the tip of the transmission shaft 66.

[0022] As a result, when the transmission shaft 66 is rotated by the drive of the conveyance motor 60, the four gears 72a, 72b, 72c, and 72d rotate. The pickup roller 32 is connected to gear 72a via a one-way clutch 74, and the separation roller 34 is connected to gear 72b via a one-way clutch 76. The one-way clutch 74 transmits the forward rotation of the gear 72a to the pickup roller 32, but does not transmit the reverse rotation of the gear 72a to the pickup roller 32. The one-way clutch 76 transmits the forward rotation of the gear 72b to the separation roller 34, but does not transmit the reverse rotation of the gear 72b to the separation roller 34. For this reason, when the conveyance motor 60 rotates in the forward direction, the pickup roller 32 and the separation roller 34 rotate in the forward direction, but when the conveyance motor 60 rotates in the reverse direction, the pickup roller 32 and the separation roller 34 do not rotate in the reverse direction. When the transport motor 60 rotates in the forward direction, the pickup roller 32 and the separation roller 34 rotate in the direction in which the document is transported.

[0023] Furthermore, the bearing 70 is fixed to the roller holder 50 coaxially with the shaft 80 of the separation roller 34, with the shaft 80 inserted through the through-hole 82. As a result, when the outer cylinder 68b of the torque limiter 68, which is fixed to the bearing 70, rotates, the roller holder 50 swings around the shaft 80 of the separation roller 34. Therefore, for example, when the conveying motor 60 rotates in the forward direction, the roller holder 50 swings around the shaft 80 of the separation roller 34 so that the pickup roller 32 descends. At this time, the drive of the conveying motor 60 rotates the transmission shaft 66, and the rotational force of the transmission shaft 66 is transmitted from the inner cylinder 68a to the outer cylinder 68b in the torque limiter 68, thereby rotating the bearing 70 and swinging the roller holder 50. Then, as shown in FIG. 2 , when the roller holder 50 swings so that the pickup roller 32 descends, the pickup roller 32 comes into contact with the upper surface of the document placed on the document tray 22. At this time, the driving force of the transmission shaft 66, which is rotated by the drive of the conveyance motor 60, exceeds a predetermined driving force, and the inner cylinder 68a rotates freely relative to the outer cylinder 68b in the torque limiter 68. As a result, the swinging of the roller holder 50 stops at the position where the pickup roller 32 abuts against the upper surface of the document placed on the document tray 22.

[0024] Furthermore, for example, when the conveying motor 60 rotates in the reverse direction, the roller holder 50 swings around the axis 80 of the separation roller 34 so as to lift the pickup roller 32. At this time, the driving of the conveying motor 60 rotates the transmission shaft 66, and the rotational force of the transmission shaft 66 is transmitted from the inner cylinder 68a to the outer cylinder 68b in the torque limiter 68, causing the bearing 70 to rotate and the roller holder 50 to swing. Then, as shown in FIG. 3 , the roller holder 50 swings so as to lift the pickup roller 32, causing the roller holder 50 to abut against a stopper (not shown). At this time, the driving force of the transmission shaft 66, which is rotated by the driving of the conveying motor 60, exceeds a predetermined driving force, and the inner cylinder 68a rotates freely relative to the outer cylinder 68b in the torque limiter 68. Therefore, the swinging of the roller holder 50 stops at the position where the roller holder 50 abuts against the stopper.

[0025] In this way, when the transport motor 60 rotates in the forward direction, the roller holder 50 swings, causing the pickup roller 32 to descend and come into contact with the upper surfaces of the documents placed on the document tray 22, and the pickup roller 32 rotates in the document transport direction. As a result, the pickup roller 32 sends out the top document placed on the document tray 22 toward the separation roller 34. At this time, because the separation roller 34 rotates together with the pickup roller 32, the document sent out by the pickup roller 32 is transported toward the inside of the transport path 30 by the separation roller 34. On the other hand, when the transport motor 60 rotates in the reverse direction, the roller holder 50 swings, causing the pickup roller 32 to ascend and separate from the upper surfaces of the documents placed on the document tray 22. At this time, the rotation of the pickup roller 32 and the separation roller 34 stops.

[0026] As described above, the pickup roller 32 and separation roller 34 are connected to the transport motor 60 via the drive transmission mechanism 62, and are rotated by the drive of the transport motor 60. The first transport roller 36, the second transport roller 38, and the discharge roller 40 are also connected to the transport motor 60 via drive transmission mechanisms (not shown), and are rotated by the drive of the transport motor 60. The drive transmission mechanisms of the first transport roller 36, the second transport roller 38, and the discharge roller 40 have substantially the same structure as the drive transmission mechanism 62, except for the torque limiter 68. When the transport motor 60 rotates in the forward direction, the first transport roller 36, the second transport roller 38, and the discharge roller 40 rotate in the document transport direction, and when the transport motor 60 rotates in the reverse direction, the first transport roller 36, the second transport roller 38, and the discharge roller 40 stop rotating. In this way, in the document feeder 10, the pickup roller 32, separation roller 34, first conveying roller 36, second conveying roller 38, and discharge roller 40 each rotate in the document conveying direction when the first conveying motor 60 rotates in the forward direction, and the rotation of the pickup roller 32, separation roller 34, first conveying roller 36, second conveying roller 38, and discharge roller 40 each stops when the first conveying motor 60 rotates in the reverse direction.

[0027] [Electrical configuration of image reading device] FIG. 7 shows the electrical configuration of the document feeder 10 and the image reader 12. The document feeder 10 and the image reader 12 include a controller 100 (an example of a control unit), a timer 102, a user I / F 18, a network I / F 106, a transport motor 60, a tray sensor 28, a height sensor 29, a rear sensor 56, a paper discharge sensor 58, and a temperature sensor 26. Note that FIG. 7 shows only the configuration related to document transport, and in reality, configuration related to, for example, image reading is also included separately. These components are connected to a bus and can communicate with each other. Note that "I / F" is an abbreviation for Interface.

[0028] The controller 100 is configured with a CPU, an ASIC (application-specific integrated circuit), and the like, and executes processing in accordance with a predetermined program. In this embodiment, the processing of the controller 100 in accordance with instructions written in the program is mainly described. In other words, in the following description, processes such as "judging," "selecting," "calculating," "deciding," "identifying," "acquiring," "receiving," and "controlling" refer to processing of the controller 100. Note that "acquiring" is used as a concept that does not necessarily require a request. In other words, the process of the controller 100 receiving data without a request is also included in the concept of "the controller 100 acquiring data." Furthermore, "data" in this specification is represented by a bit string that can be read by the controller. Data with essentially the same meaning but different formats are treated as the same data. The same applies to "information" in this specification.

[0029] The user I / F 18 is a touch panel that also functions as a display, and is interposed between the user operating the image reading device 12 and the controller 100, providing various information to the user and functioning as a user interface that accepts user operations. The user I / F 18 also allows the user to select various options, buttons, icons, objects, etc. displayed on the liquid crystal display using the touch panel. However, the user interface that accepts user operations is not limited to a touch panel and may also be physical keys. In other words, a liquid crystal display and physical keys may be provided as a user interface.

[0030] In this embodiment, for convenience, the objects operated and selected by the user using the image reading device 12 or the administrator managing the image reading device 12 are referred to as "options," "buttons," "icons," "objects," etc., but they may be replaced with other words.

[0031] The network I / F 106 is a network I / F that connects the image reading device 12 to a network wirelessly or via a wired connection. For example, the image reading device 12 can receive a reading instruction transmitted from a terminal (such as a PC) connected to the same network via the network I / F 106 and execute a scan process according to the received instruction.

[0032] The conveyance motor 60 is a motor that drives the pickup roller 32, separation roller 34, first conveyance roller 36, second conveyance roller 38, and discharge roller 40. However, each roller may have its own drive source. The tray sensor 28 is a sensor that detects the presence or absence of a document placed on the document tray 22. The height sensor 29 is a sensor that detects the height of a document placed on the document tray 22. The rear sensor 56 is a sensor that detects the passage of a document over the first conveyance roller 36 in the conveyance path 30. The discharge sensor 58 is disposed at the rear end of the conveyance path 30 (an example of a discharge section) and is a sensor that can detect the discharge of a document from the rear end of the conveyance path 30 by detecting the presence or absence of a document at the rear end of the conveyance path 30. The temperature sensor 26 is a sensor that detects the ambient temperature, i.e., the air temperature, of the environment in which the image reading device 12 is disposed.

[0033] [Control processing by the controller] Next, among the various processes executed by the controller 100 of the image reading device 12 having the above configuration, a document re-feeding operation executed when a document is not fed from the document tray 22 will be described with reference to Figures 8 and 9. Figures 8 and 9 are flowcharts of the image reading process of the image reading device 12. The image reading process is executed when the image reading device 12 is powered on and receives an image reading instruction via the user I / F 18 or the network I / F 106. Note that each process shown in the flowcharts in Figures 8 and 9 below is stored in a memory (not shown) provided in the image reading device 12 and is executed by the controller 100.

[0034] First, in step (hereinafter abbreviated as S) 10, the controller 100 determines whether or not a document is present on the document placement surface 22a of the document tray 22 based on the detection value of the tray sensor 28. If a document is not present on the document placement surface 22a of the document tray 22 (S10: NO), the controller 100 executes a reading process (FB reading process) of the document placed in the reading area of ​​the flatbed of the contact glass 14 in S12. Then, the processing by the program ends. On the other hand, if a document is present on the document placement surface 22a of the document tray 22 (S10: YES), the controller 100 sets the set time TL1 to FP (an example of a first predetermined time) in S14. Here, FP is the time required for the leading edge of the document placed on the document placement surface 22a to reach the rear sensor 56. Therefore, a time slightly longer than the time obtained by dividing the distance between the leading edge of the document placed on the document placement surface 22a and the rear sensor 56 by the document transport speed in the document feeder 10 is set as FP.

[0035] Next, in S16, the controller 100 resets the RT count to 0, and in S18, the controller 100 resets the time measured by the timer 102 to 0. Subsequently, in S20, the controller 100 determines whether the value detected by the temperature sensor 26, i.e., whether the air temperature detected by the temperature sensor 26, is 30°C or higher or 10°C or lower. If the air temperature detected by the temperature sensor 26 is 30°C or higher or 10°C or lower (S20: YES), the controller 100 sets the RT flag to 1 in S22. On the other hand, if the air temperature detected by the temperature sensor 26 is higher than 10°C and lower than 30°C (S20: NO), the controller 100 sets the RT flag to 0 in S24. Then, when the RT flag is set to either 0 or 1, the controller 100 rotates the carry motor 60 in the forward direction in S26. As a result, in document feeder 10, roller holder 50 swings, causing pickup roller 32 to come into contact with the uppermost document placed on document placement surface 22a, and pickup roller 32, separation roller 34, first conveyance roller 36, second conveyance roller 38, and discharge roller 40 to rotate in the document conveyance direction. In other words, the processing of S26 starts a paper feed operation in which the first document of the documents placed on document tray 22 is fed toward conveyance path 30.

[0036] Next, in S28, the controller 100 determines, based on the detection value of the rear sensor 56, whether the document has been transported to the arrangement position of the rear sensor 56, that is, to the downstream side of the first transport rollers 36. At this time, if the document has been transported to the downstream side of the first transport rollers 36 (S28: YES), the controller 100 executes a document reading process (ADF reading process) by the reading device 16 in S30. On the other hand, if the document has not been transported to the downstream side of the first transport rollers 36 (S28: NO), the controller 100 determines in S38 whether the time measured by the timer 102 has exceeded the set time TL1. At this time, if the time measured by the timer 102 has not exceeded the set time TL1 (S38: NO), the process of S28 is executed. That is, the processes of S28 and S38 are repeatedly executed until the time measured by the timer 102 exceeds the set time TL1, and if the document is conveyed to the downstream side of the first conveyor roller 36 before the time measured by the timer 102 exceeds the set time TL1 (S28: YES), the ADF reading process is executed in S30. Then, when the ADF reading process is executed, the controller 100 determines in S32 whether or not a document is present on the document placement surface 22a of the document tray 22 based on the detection value of the tray sensor 28. If no document is present on the document placement surface 22a of the document tray 22 (S32: NO), the controller 100 stops the rotation of the conveyor motor 60 in S34. This completes the ADF reading process and ends the processing by the program.

[0037] Furthermore, when there are documents on the document placement surface 22a of the document tray 22 (S32: YES), in order to feed the second and subsequent (N+1) documents placed on the document tray 22, the controller 100 sets the set time TL1 to NP (an example of a second predetermined time) in S36. In this way, the set time TL1 is set to FP when the first document is fed, and to NP when the second and subsequent documents are fed. Note that NP is the time required for the trailing edge of the preceding document, i.e., the document (Nth document) transported before the document to be fed (N+1) passes the rear sensor 56 and is discharged onto the discharge tray 24. For this reason, NP is set to a time slightly longer than the time obtained by dividing the distance between the rear sensor 56 and the end point of the transport path 30, i.e., the position of the transport path 30 immediately before it reaches the discharge tray 24, by the document transport speed of the document feeder 10.

[0038] Then, the processes of S16 to S26 are executed by the controller 100. This starts a paper feeding operation in which the (N+1)th document among the documents placed on the document tray 22 is fed toward the conveying path 30. Then, the processes of S28, S30, S32, and S38 are executed, thereby executing the ADF reading process for the (N+1)th document.

[0039] In the above description, the document is transported downstream of the first transport roller 36 (S28: YES) before the time measured by the timer 102 exceeds the set time TL1 (S38: NO). On the other hand, there are cases where the time measured by the timer 102 exceeds the set time TL1 (S38: YES). In such cases, the pickup roller 32 may feed the document empty, possibly resulting in a non-feed of the document. Therefore, it is desirable to perform the document feeding operation by the pickup roller 32 again. On the other hand, even if the time measured by the timer 102 exceeds the set time TL1, the pickup roller 32 may not feed the document empty, and the document may be fed by the pickup roller 32. However, there are cases where the document jams before it reaches the rear sensor 56. In such cases, if the pickup roller 32 attempts to feed the document again, the document fed by the re-feed operation may come into contact with the document that previously jammed, potentially causing a further paper jam. In view of this, the document re-feeding operation is carried out only when the pickup roller 32 is likely to feed the document empty.

[0040] Specifically, if the time measured by timer 102 exceeds set time TL1 (S38: YES), controller 100 determines in S41 whether the RT flag is set to 1. If the RT flag is set to 1, the temperature detected by temperature sensor 26 is 10°C or lower or 30°C or higher. If the RT flag is set to 0, the temperature detected by temperature sensor 26 is above 10°C and below 30°C. When the temperature detected by temperature sensor 26 is low, below 10°C, humidity tends to be low, and the coefficient of friction of pickup roller 32 decreases, making it more likely that pickup roller 32 will feed the document empty. When the temperature detected by temperature sensor 26 is high, above 30°C, the driving force of transport motor 60 decreases, making it more likely that pickup roller 32 will feed the document empty. On the other hand, when the temperature detected by temperature sensor 26 is above 10°C and below 30°C, the incidence of pickup roller 32 feeding the document empty is low. Therefore, when the air temperature detected by temperature sensor 26 is above 10°C and below 30°C, that is, when the RT flag is set to 0 (S41: NO), even if the time measured by timer 102 exceeds set time TL1, no empty feeding of the document by pickup roller 32 has occurred, and it is assumed that the reason the document has not been transported to rear sensor 56 is that the document fed by pickup roller 32 has jammed before reaching rear sensor 56. Therefore, when the RT flag is set to 0 (S41: NO), controller 100 displays an error screen on user I / F 18 in S50. Then, controller 100 stops rotation of transport motor 60 in S52. This ends the processing by the program.

[0041] On the other hand, if the RT flag is set to 1 (S41: YES), it is assumed that the pickup roller 32 is empty-feeding the document, and so in S42 the controller 100 determines whether the RT count is 3. In this case, since the RT count is set to 0, it is determined that the RT count is not 3 (S42: NO), and in S44 the controller 100 increments the RT count by 1. That is, the controller 100 sets the RT count to 1. Then, the controller 100 executes the document refeed operation. That is, in S46 the controller 100 rotates the conveyance motor 60 in the reverse direction a predetermined number of times. This causes the roller holder 50 to swing in a direction that lifts the pickup roller 32. Note that while the roller holder 50 is swinging in a direction that lifts the pickup roller 32, the rotation of all rollers, including the pickup roller 32, separation roller 34, first conveyance roller 36, second conveyance roller 38, and discharge roller 40, is stopped. Then, in S48, the controller 100 rotates the conveying motor 60 in the forward direction. As a result, the roller holder 50 swings in a direction that lowers the pickup roller 32. At this time, all rollers, including the pickup roller 32, separation roller 34, first conveying roller 36, second conveying roller 38, and discharge roller 40, rotate in the document conveying direction. This executes the document re-feed operation.

[0042] In this way, when the document refeeding operation is performed, the pickup roller 32 rises once and then descends, so that the document placed on the document placement surface 22a is pressed by the pickup roller 32. This allows the document to be fed appropriately during the document refeeding operation. More specifically, for example, the document placed on the document placement surface 22a may be curled upward near the center. In such a case, the document may press the pickup roller 32 upward, making it difficult for the pickup roller 32 to feed the document, and the pickup roller 32 may be prone to empty feeding of the document. Therefore, when the document refeeding operation is performed, the pickup roller 32 is not simply rotated in the transport direction, but is instead raised once and then descended. This causes the pickup roller 32 to rotate in the document transport direction while correcting the curl of the document due to the kinetic moment generated by the descent of the pickup roller 32. This allows the document to be fed appropriately during the document refeeding operation.

[0043] In this way, when the document refeed operation is performed, the processes from S18 onward are executed. That is, the RT count is not reset, but only the time measured by the timer 102 is reset. Then, during the document refeed operation, it is determined whether the document is transported downstream of the first transport rollers 36 before the time measured by the timer 102 exceeds the set time TL1 (S38: NO). At this time, if the document is transported downstream of the first transport rollers 36 before the time measured by the timer 102 exceeds the set time TL1, that is, if the document refeed operation has resolved the empty document feed, the ADF reading process is executed (S30). On the other hand, if the document is not transported downstream of the first transport rollers 36 before the time measured by the timer 102 exceeds the set time TL1, that is, if the document refeed operation has not resolved the empty document feed, the controller 100 determines in S42 whether the RT count is 3. At this time, since the RT count is set to 1, it is determined that the RT count is not 3 (S42: NO), and the controller 100 adds 1 to the RT count (S44). That is, the controller 100 sets the RT count to 2. Then, the controller 100 executes a refeed operation for the document (S46, S48). That is, although the first refeed operation was executed, a second refeed operation is executed for the document in which empty feeding occurred in the first refeed operation as well.

[0044] Subsequently, after the second refeed operation is performed, the processes from S18 onward are executed. At this time, if the document is not conveyed downstream of the first conveyance roller 36 before the time measured by the timer 102 exceeds the set time TL1 during the second refeed operation, the controller 100 determines in S42 whether the RT count is 3. At this time, since the RT count is set to 2, it is determined that the RT count is not 3 (S42: NO), and the controller 100 increments the RT count by 1 (S44). That is, the controller 100 sets the RT count to 3. Then, the controller 100 executes the document refeed operation (S46, S48). That is, the second refeed operation was executed, but a third refeed operation is executed for the document in which empty feeding occurred during the second refeed operation.

[0045] Then, even after the third refeed operation is performed, if the document has not been transported downstream of the first transport roller 36 before the time measured by the timer 102 exceeds the set time TL1, the controller 100 determines in S42 whether the RT count is 3. At this time, since the RT count is set to 3, it is determined that the RT count is 3 (S42: YES), and the controller 100 displays an error screen on the user I / F 18 in S50. Then, in S52, the controller 100 stops the rotation of the transport motor 60. This ends the processing by the program. In other words, if the empty document feed is not resolved even after the third refeed operation is performed on the same document, an error screen is displayed on the user I / F 18, and the rotation of the transport motor 60 is stopped.

[0046] [Second embodiment] The document re-feeding operation of the second embodiment will be described with reference to Figures 10 and 11. Note that the second embodiment has many commonalities with the first embodiment, and therefore, in the description of the second embodiment, the description of the commonalities with the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0047] In the second embodiment, when it is determined that a document is placed on the document tray 22 (S60: YES), the set time TL1 is set to FP. On the other hand, the second embodiment does not execute the process equivalent to S36 in the first embodiment. Therefore, in the first embodiment, the set time TL1 is set to FP when the first document is fed and is set to NP when the second and subsequent documents are fed, but in the second embodiment, the set time TL1 is set to FP when all documents are fed.

[0048] In the second embodiment, if the document is not conveyed downstream of the first conveyor rollers 36 before the time measured by the timer 102 exceeds the set time TL1, that is, if the time measured by the timer 102 exceeds the set time TL1 (S88: YES) while the document is not conveyed downstream of the first conveyor rollers 36 (S78: NO), the controller 100 determines in S89 based on the detection value of the paper discharge sensor 58 whether the document has been discharged from the conveyance path 30, that is, whether the document conveyed before the document to be fed has been discharged from the conveyance path 30. Specifically, if the paper discharge sensor 58 detects a document conveyed before the document to be fed, it determines that the document has not been discharged (S89: NO); if not, it determines that the document has been discharged (S89: YES). At this time, if the document has been discharged from the conveyance path 30 (S89: YES), the processes from S91 onwards are executed. The process from S91 onwards is the same as the process from S41 onwards in the first embodiment, and if the RT flag is 1 and the RT count is not 3, the document re-feed operation is carried out.

[0049] On the other hand, if the document has not been discharged from the conveying path 30 (S89: NO), the controller 100 determines in S90 whether the time measured by the timer 102 exceeds TL2. TL2 is the sum of TL1 and the time required for the document being read by the reading device 16 to be completely discharged from the conveying path 30. For this reason, TL2 is set to a time slightly longer than the sum of the time obtained by dividing the distance between the installation position of the reading device 16 and the end point of the conveying path 30 by the document conveying speed of the document feeder 10 and TL1. If the time measured by the timer 102 does not exceed TL2 (S90: NO), the process of S89 is executed. On the other hand, if the time measured by the timer 102 exceeds TL2 (S90: YES), the processes of S100 and S84 are executed. The processes of S100 and S84 are the same as the processes of S50 and S34 in the first embodiment, and an error screen is displayed on the user I / F 18.

[0050] That is, in the second embodiment, the re-feeding operation of the document to be fed is put on hold until the document that was transported before the document to be fed is discharged from the transport path 30 (S89: YES). This makes it possible to temporarily stop the re-feeding operation of the document to be fed while the document that was transported first is being read by the reading device 16. Furthermore, if the time measured by the timer 102 exceeds TL2 (S90: YES) in a state where the document that was transported first has not been discharged from the transport path 30 (S89: NO), an error screen is displayed on the user I / F 18. This makes it possible to prevent the leading edge of the document fed by the re-feeding operation of the document from coming into contact with the trailing edge of the document that was transported first.

[0051] [Third embodiment] The document re-feeding operation of the third embodiment will be described with reference to Fig. 12. Note that the third embodiment also has many commonalities with the first embodiment, and therefore in the description of the third embodiment, the description of the commonalities with the first embodiment will be omitted, and only the differences from the first embodiment will be described.

[0052] In the third embodiment, after TL1 is set to FP or NP (S113, S114), the controller 100 determines in S115 whether the height of the document placed on the document placement surface 22a is 15 mm or more based on the value detected by the height sensor 29. At this time, if the document height is 15 mm or more (S115: YES), the processes of S116 to S120 are executed. The processes of S116 to S120 are the same as the processes of S16 to S20 in the first embodiment, and the RT flag is set to either 0 or 1 depending on the air temperature detected by the temperature sensor 26. On the other hand, if the document height is less than 15 mm (S115: NO), the controller 100 sets the RT flag to 0 in S124.

[0053] That is, in the third embodiment, if the height of the original document is less than 15 mm, the original document refeeding operation is not performed. If the height of the original document is 15 mm or more, the original document refeeding operation is performed in accordance with the temperature detected by the temperature sensor 26. This is because empty feeding of the original document is likely to occur when the original document height is high, and empty feeding of the original document is unlikely to occur when the original document height is low. Specifically, as shown in FIG. 3 , at the start of the transport path 30, i.e., at a portion of the transport path 30 near the original document placement surface 22a, the upper part of the transport path 30 is partitioned by a partition wall 110. Therefore, if the height of the original document placed on the original document placement surface 22a is 15 mm or more, i.e., if the original document is high, and the center portion of the topmost original document curls upward, the original document may come into contact with the partition wall 110. In this way, if the original document placed on the original document placement surface 22a comes into contact with the partition wall 110, the friction between the partition wall 110 and the original document may prevent the pickup roller 32 from properly feeding the original document, resulting in empty feeding. On the other hand, when the height of the documents placed on document placement surface 22a is less than 15 mm, that is, when the document is low, even if the center of the top document curls upward, the document is unlikely to come into contact with partition wall 110, and empty feeding due to transport load or the like is unlikely to occur, so there is a high possibility that a jam has actually occurred. For this reason, the document refeed operation is not performed when the document height is less than 15 mm, but when the document height is 15 mm or more, the document refeed operation is performed in accordance with the air temperature detected by temperature sensor 26. This makes it possible to not perform the document refeed operation when empty feeding of documents is unlikely to occur, and to perform the document refeed operation when empty feeding of documents is likely to occur.

[0054] As described above in detail, document feeder 10 according to this embodiment includes pickup roller 32 that feeds documents placed on document placement surface 22a, transport motor 60 that rotates pickup roller 32, rear sensor 56 that is disposed downstream of pickup roller 32 in the document transport direction and whose output changes depending on the presence or absence of a document, temperature sensor 26 for detecting air temperature, timer 102, and controller 100. When controller 100 receives a document feed command, it rotates transport motor 60 to perform a document feed operation, starts measurement by timer 102 from a predetermined timing, and determines that a document has not been fed, i.e., that empty feeding has occurred, if the rear sensor 56 does not output a signal corresponding to the presence of a document and the measurement time by timer 102 has elapsed for set time TL1, and determines whether or not to perform a document refeed operation based on the temperature detected by temperature sensor 26. According to the document feeder 10, the document re-feeding operation can be performed in a manner that is less likely to damage the document by performing the document re-feeding operation in accordance with various usage environments, thereby saving the user unnecessary work and protecting the document.

[0055] Furthermore, the controller 100 executes the document re-feed operation when the temperature detected by the temperature sensor 26 is equal to or higher than 30° C. or equal to or lower than 10° C. This makes it possible to execute the document re-feed operation when empty document feeding is likely to occur.

[0056] Furthermore, if the empty document feed state is not resolved even after the document re-feed operation has been repeated three times, the controller 100 stops the document feed operation. This prevents unnecessary re-feed operations from being repeated, prevents damage to the document feeder 10 or the document, and reduces the user's waiting time due to the document re-feed operation.

[0057] Furthermore, if the empty document feed state is not resolved even after the document re-feed operation is repeated three times, the controller 100 displays an error screen on the user I / F 18. This makes it possible to notify the user that the empty document feed state is not resolved.

[0058] Furthermore, when the time measured by timer 102 exceeds set time TL1 and controller 100 determines that empty feeding of the document has occurred, controller 100 separates pickup roller 32 from the document and then brings it into contact with the document again to perform the document re-feed operation. This corrects curls, etc., in the document, making it possible to properly perform the document re-feed operation.

[0059] Furthermore, when the time measured by timer 102 exceeds set time TL1 and controller 100 determines that empty feeding of the document has occurred, controller 100 rotates conveyance motor 60 in the reverse direction to swing roller holder 50 to separate pickup roller 32 from the document, and then rotates conveyance motor 60 in the forward direction to swing pickup roller 32 to bring it into contact with the document again, thereby executing a document re-feed operation. This makes it easy to separate pickup roller 32 from the document and bring it into contact with the document.

[0060] Furthermore, when the time measured by the timer 102 has exceeded the set time TL1 and it is determined that empty feeding of the document has occurred, the controller 100 waits for the document refeed operation when the paper discharge sensor 58 outputs a signal corresponding to the presence of a document, that is, when the document transported previously has not been discharged from the transport path 30. Then, when the paper discharge sensor 58 outputs a signal corresponding to the absence of a document, that is, when the document transported previously has been discharged from the transport path 30, the controller 100 executes the document refeed operation. This makes it possible to temporarily stop the refeed operation of the document to be fed while the document transported previously is being read by the reading device 16.

[0061] Furthermore, when the time measured by the timer 102 exceeds the set time TL1 and the controller 100 determines that empty feeding of the document has occurred, if the time measured by the timer 102 exceeds TL2 while the document discharge sensor 58 is still outputting a signal corresponding to the presence of a document and while the document that was previously transported has not been discharged from the transport path 30, the controller 100 stops the document feeding operation without performing the document re-feeding operation. This makes it possible to prevent the leading edge of the document fed by the document re-feeding operation from contacting the trailing edge of the document that was previously transported.

[0062] Furthermore, the controller 100 does not execute the document re-feed operation if the document height indicated by the output from the height sensor 29 is less than 15 mm. When the height of the document placed on the document placement surface 22a is less than 15 mm, that is, when the document is low, empty document feed is unlikely to occur. In this way, even when empty document feed is unlikely to occur, if the time measured by the timer 102 exceeds the set time TL1, there is a high possibility that the document that was previously transported has caused a paper jam. Therefore, by not executing the document re-feed operation when the document height indicated by the output from the height sensor 29 is less than 15 mm, further document jams can be prevented.

[0063] Furthermore, the controller 100 sets the set time TL1 to either FP, which is the time required for a document placed on the document placement surface 22a to reach the rear sensor 56, or NP, which is the time required for a document transported in advance to pass through the rear sensor 56, pass the reading device 16, and be discharged from the transport path 30. This makes it possible, for example, to make the set time TL1 set for the first document transported different from the set time TL1 set for the second or subsequent document transported.

[0064] In the document feeder 10, the drive of the first transport motor 60 is transmitted to the pickup roller 32, the separation roller 34, and the discharge roller 40 by a drive transmission mechanism. When the transport motor 60 rotates in the reverse direction, the drive transmission mechanism cuts off the transmission of the drive of the transport motor 60 to the pickup roller 32, the separation roller 34, and the discharge roller 40. This prevents the document from flowing backward in the transport path 30.

[0065] Furthermore, in the document feeder 10, a torque limiter 68 is disposed between the transmission shaft 66 of the transport motor 60 and the roller holder 50, and the torque limiter 68 swings the roller holder 50. This allows the roller holder 50 to swing appropriately.

[0066] The present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications are possible within the scope of the present invention. For example, in the first and third embodiments, FP is set as the set time TL1 for the first document and NP is set for the second and subsequent documents, but the longer of FP and NP may be set as the set time TL1 for all documents to be fed. By setting the longer of FP and NP as the set time TL1 in this way, it is possible to reliably stop the re-feeding operation of the document to be fed while the document that was previously transported is being read by the reading device 16.

[0067] Furthermore, in the above embodiment, NP is the time required from when the trailing edge of the precedingly transported document passes the rear sensor 56 until it is discharged onto the discharge tray 24, but it may also be the time required from when the trailing edge of the precedingly transported document passes the rear sensor 56 until it passes the reading device 16. In other words, NP may be the time required from when the trailing edge of the precedingly transported document passes the rear sensor 56 until it passes at least the reading device 16.

[0068] Furthermore, in the above embodiment, the document feeder 10 arranged in the image reading device 12 is used as an example of the sheet conveying device, but the sheet conveying device may also be arranged in, for example, a printer, a facsimile machine, or a multifunction device having a printer function and a scanner function. [Explanation of symbols]

[0069] 10: document feeder (sheet transport device), 16: reading device (reading unit), 18: User I / F (display unit), 22a: Document placement surface (sheet placement surface), 26: Temperature sensor, 29: Height sensor, 32: Pickup roller, 34: Separation roller, 40: Paper discharge roller, 50: Roller holder (pickup arm), 56: Rear sensor (sheet sensor), 58: Paper discharge sensor, 60: Conveyor motor (motor), 62: Drive transmission mechanism (drive transmission unit), 68: Torque limiter, 100: Controller (control unit), 102: Timer,

Claims

1. a pickup roller that feeds a sheet placed on the sheet placement surface; a motor that rotates the pickup roller; a sheet sensor disposed downstream of the pickup roller in the sheet conveying direction, the output of which changes depending on the presence or absence of a sheet; a temperature sensor for detecting the temperature; A timer and a control unit, The control unit When a paper feed command is received, the motor is rotated to perform a paper feed operation, the timer is started to measure time from a predetermined timing, and if the sheet sensor does not output a signal corresponding to the presence of a sheet and the time measured by the timer has elapsed for a predetermined time, it is determined that a sheet has not been fed, and based on the temperature detected by the temperature sensor, it is determined whether or not to perform a sheet re-feed operation.

2. The control unit 2. The sheet conveying device according to claim 1, wherein the sheet re-feeding operation is executed when the temperature detected by the temperature sensor is equal to or higher than a first predetermined value or equal to or lower than a second predetermined value that is lower than the first predetermined value.

3. The control unit 3. The sheet transport device according to claim 2, wherein the sheet feeding operation is stopped when the sheet non-feeding state is not resolved even after the sheet re-feeding operation is performed a predetermined number of times.

4. Further comprising a display unit, The control unit 4. The sheet transport device according to claim 3, wherein an error is displayed on the display unit when the sheet non-feed state is not resolved even after the sheet re-feed operation is performed a predetermined number of times.

5. The control unit A sheet conveying device as described in any one of claims 1 to 4, characterized in that when the time measured by the timer exceeds the predetermined time and it is determined that a sheet has not been fed, the pickup roller is moved away from the sheet and then brought into contact with the sheet again to perform a sheet re-feeding operation.

6. a pickup arm that rotatably holds the pickup roller and swings around an axis; The control unit The sheet conveying device according to claim 5, characterized in that when the time measured by the timer exceeds the predetermined time and it is determined that a sheet has not been fed, the motor is rotated in a direction opposite to the sheet conveying direction to oscillate the pickup roller, thereby separating the pickup roller from the sheet, and then the motor is rotated in the sheet conveying direction to oscillate the pickup roller, thereby bringing it into contact with the sheet again, thereby performing a sheet re-feeding operation.

7. Further, a sheet discharge sensor whose output changes depending on whether or not a sheet is placed in the discharge section is provided, The control unit A sheet conveying device as described in any one of claims 1 to 4, characterized in that when the timer's counting time exceeds the predetermined time and it is determined that a sheet has not been fed, the device waits for a sheet re-feed operation while the paper discharge sensor outputs a signal corresponding to the presence of a sheet, and performs a sheet re-feed operation when the paper discharge sensor outputs a signal corresponding to the absence of a sheet.

8. The control unit 8. The sheet conveying device according to claim 7, wherein when the time counted by the timer exceeds the predetermined time and it is determined that a sheet has not been fed, if the time counted by the timer exceeds a set time that is longer than the predetermined time while the paper discharge sensor is still outputting a signal corresponding to the presence of a sheet, the sheet feeding operation is stopped without performing a sheet re-feeding operation.

9. a height sensor whose output changes depending on the height of a sheet placed on the sheet placement surface; The control unit 5. The sheet conveying device according to claim 1, wherein the sheet re-feeding operation is not performed when the sheet height indicated by the output from the height sensor is less than a predetermined height.

10. The control unit A sheet conveying device as described in any one of claims 1 to 4, characterized in that the specified time is set to either a first specified time, which is the time required for the leading edge of a sheet placed on the sheet placing surface to reach the sheet sensor, or a second specified time, which is the time required for the trailing edge of a preceding sheet conveyed ahead of the sheet to pass through at least the sheet reading section after passing through the sheet sensor.

11. The control unit 11. The sheet conveying apparatus according to claim 10, wherein the predetermined time is set to the longer of the first predetermined time and the second predetermined time.

12. A paper discharge roller; A separation roller; a drive transmission unit that transmits the drive of the motor to the pickup roller, the paper discharge roller, and the separation roller, The drive transmission unit is 5. A sheet conveying device according to claim 1, wherein when the motor rotates in a direction opposite to the sheet conveying direction, the transmission of drive power from the motor to the pickup roller, the discharge roller, and the separation roller is interrupted.

13. a pickup arm that rotatably holds the pickup roller and swings around an axis; 13. The sheet transport device according to claim 12, further comprising a torque limiter disposed between the drive shaft of the motor and the pickup arm, for swinging the pickup arm.

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