Sheet feeding device

Abstract

To reduce a time delay in feeding a sheet by preventing failure in feeding the sheet as a pickup roller is not in contact with the sheet while suppressing multiple feeding or jamming of the sheet.SOLUTION: A sheet feeding device comprises: a sheet loading table 1 loaded with a sheet; taking-in means for taking the sheet loaded on the sheet loading table 1 into a device body; feeding means for feeding the sheet taken in by the taking-in means; separating means abutting on the feed means to separate a sheet to be fed from a plurality of sheets; and sheet detecting means for detecting whether a sheet is present between the feeding means and the separating means, wherein the taking-in means is controlled based upon a detection result of the sheet detecting means to operate to take in the sheet.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device capable of feeding sheets and a technique for detecting a sheet feeding state in an image reading device equipped with the sheet feeding device. [Background technology]

[0002] Patent document 1, for example, discloses a method for detecting the sheet feeding state and avoiding feeding failures in a sheet feeding device that sequentially separates and feeds multiple sheets and an image reading device that reads images on the fed sheets.

[0003] The sheet feeding device described in Patent Document 1 discloses a method for detecting the rotational state of a separation roller (brake roller) when a sheet is fed, and for maintaining the pickup roller in a non-contact state with respect to the next sheet to be fed (the subsequent sheet) if it is determined that the separation roller is not rotating. If multiple sheets enter between the feed roller and the separation roller, which is in contact with and opposite the feed roller, while the sheet is being fed by the feed roller (separator roller), the separation roller does not rotate, preventing sheets other than the one being fed from being conveyed in the conveyance direction. On the other hand, if no sheets other than the sheet being fed have entered, the separation roller rotates along with the sheet being fed. Depending on the rotational state of the separation roller, it is determined whether to bring the pickup roller into contact with the sheet or maintain the non-contact state. Through this control, the pickup roller does not apply more pressure than necessary to the sheet, preventing double sheet feeding and jamming. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5075089 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the adhesion of paper dust to the surface of the separation roller or its deterioration can reduce the coefficient of friction on the surface of the separation roller, causing the separation roller to not rotate along with the feed roller or the sheet being fed. When the separation roller does not rotate due to the above reasons, the method of Patent Document 1 will determine that the following sheet has entered between the feed roller and the separation roller, even if the following sheet has not entered between the feed roller and the separation roller. In this case, the pickup roller is not in contact with the following sheet, so the sheet cannot be fed. The pickup roller must be changed from a non-contact state to a contact state and the feeding must be restarted. This results in a delay in completing the feeding operation. [Means for solving the problem]

[0006] In view of the above, a sheet feeding device according to the present invention comprises: a sheet loading table on which sheets are loaded; a take-in unit that takes in the sheets stacked on the sheet stacking table into the apparatus body; a feeding means for feeding the sheet taken in by the taking-in means; a separating means for contacting the feeding means and separating a sheet to be fed from the plurality of sheets; a sheet detecting means for detecting the presence or absence of a sheet between the feeding means and the separating means; The sheet taking-in unit is characterized in that the sheet taking-in operation is controlled based on the detection result by the sheet detecting unit. [Effects of the Invention]

[0007] In this invention, a sensor is used to detect the presence or absence of a sheet within the contact area (nip area) between the feed roller and the separation roller. Therefore, it is possible to detect whether a subsequent sheet has entered between the feed roller and the separation roller immediately before starting to feed the subsequent sheet. By using the sensor, it is possible to prevent the problem of the subsequent sheet not being picked up because the pickup roller is not in contact with the subsequent sheet, and the sheet having to be fed again. As a result, it is possible to reduce the delay in the time until sheet feeding is completed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically showing the configuration of an image reading apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating the configuration of the main part of the image reading device of FIG. 1. [Figure 3] Cross section of the pickup roller and its surroundings [Figure 4] FIG. 3 is a partial cross-sectional view schematically showing the arrangement of components around the optical sensor. [Figure 5] FIG. 5 is a partial cross-sectional view of FIG. 4 as viewed from the upstream side in the conveying direction. [Figure 6] 10 is a flowchart showing the procedure of a feeding operation. [Figure 7] FIG. 10 is a partial cross-sectional view schematically showing the arrangement of components around an optical sensor according to a second embodiment. [Figure 8] FIG. 11 is a partial cross-sectional view schematically showing the arrangement of components around an optical sensor according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described.

[0010] First Embodiment FIG. 1 is a partial cross-sectional view illustrating the configuration of an image reading device, which is an example of a sheet feeding device, according to a first embodiment, and FIG. 2 is a schematic diagram illustrating the configuration of the main parts of the image reading device of FIG. 1.

[0011] 1 and 2, the image reading device 200 includes a sheet take-in unit 101. A plurality of sheets are stacked on a stacking table 1, which is configured to be freely movable up and down. A stacking table drive motor 2 raises and lowers the sheet stacking table 1. A sheet detection sensor 3 detects that the sheets stacked on the sheet stacking table 1 are at the sheet take-in position. If the sheets stacked on the sheet stacking table 1 are not at the sheet take-in position, the stacking table drive motor 2 is driven to move the sheet stacking table 1 so that the top surface of the sheets is at the take-in position. A sheet stacking detection sensor 4 detects that sheets are stacked on the sheet stacking surface 1a of the sheet stacking table 1.

[0012] The pickup roller 5 is provided opposite the sheet stacking tray 1, and functions as a take-in means that sends out the sheets stacked on the sheet stacking tray 1 to the feed roller 7 and takes in the sheets into the main body of the apparatus. The pickup motor 6 rotates the pickup roller 5. In FIG. 2, the upper surface of the sheet is at the sheet take-in position, and when the pickup roller 5 is rotated, the sheet will start to be taken in.

[0013] The feed roller 7 is provided downstream of the pickup roller 5 in the conveying direction, and is driven by a feed motor 8 to rotate in a direction to feed the sheet downstream in the conveying direction, functioning as a feeding means. The feed roller 7 is connected to the feed motor 8 via a one-way clutch (not shown), and the drive force of the feed motor 8 is transmitted in only one direction. When feeding is performed by the feed motor 8, a driving force is transmitted to the feed roller 7, but when the sheet is conveyed by conveying rollers 14, 15 or the like at a speed exceeding the speed of the feed roller 7, the rotation of the feed motor 8 is not transmitted by the one-way clutch, and the feed roller 7 is rotated in accordance with the conveyance of the sheet.

[0014] The separation roller 9 faces the feed roller 7 across the conveyance path and is biased toward the feed roller 7. The separation roller 9 receives a rotational force from a torque limiter (not shown) in a direction that pushes the sheet back upstream in the conveyance direction (counterclockwise in the figure). When only one sheet is present between the feed roller 7 and the separation roller 9, the rotational force in the clockwise direction in the figure due to friction between the fed sheet and the separation roller 9 exceeds the upper limit of the rotational force in the counterclockwise direction set by the torque limiter, so the separation roller 9 rotates clockwise in the figure following the feed roller 7 (co-rotates). On the other hand, when multiple sheets are present between the feed roller 7 and the separation roller 9, the separation roller 9 functions as a separating means, receiving a rotational force from the torque limiter in a direction that pushes the sheet back upstream in the conveyance direction, so that only the sheet to be fed that contacts the feed roller 7 is conveyed downstream.

[0015] As described above, the feed roller 7 has the function of feeding sheets downstream, and the separation roller 9 has the function of preventing sheets from being fed downstream. When multiple sheets are stacked and fed into the contact area (nip area) between the feed roller 7 and the separation roller 9, only the topmost sheet to be fed is fed downstream, and the other sheets are not fed downstream, so that the stacked sheets are separated and fed.

[0016] The separation roller 9 may be replaced with a separation pad, which may come into contact with the sheets to prevent multiple sheets from being conveyed downstream.

[0017] A double feed detection sensor 30 is provided downstream in the conveying direction of the feed roller 7. The double feed detection sensor 30 detects whether the sheets have been separated one by one by the separation roller 9. In this embodiment, a detection device using an ultrasonic transmitter / receiver is used as the double feed detection sensor 30, and detects double feed based on the amount of ultrasonic wave attenuation between the transmitter / receivers across the conveying path.

[0018] The conveying motor 11 rotates the conveying rollers 14, 16, 18, and 20 to convey the sheet to an image reading position where the image on the sheet is read by the image reading sensors 12 and 13. When the conveying rollers 14, 16, 18, and 20 are rotated, the opposite conveying rollers 15, 17, 19, and 21 are rotated to convey the sheet. The conveying motor 11 also drives each roller so that the sheet conveying speed can be changed according to settings such as the optimum speed for reading the sheet and the sheet resolution. The resist clutch 22 drives or stops the drive of the conveying roller 14 by transmitting or interrupting the rotational drive force of the conveying motor 11 to the conveying roller 14.

[0019] The conveying roller pair consisting of conveying rollers 16 and 17, the conveying roller pair consisting of conveying rollers 18 and 19, and the roller pair consisting of conveying rollers 20 and 21 convey the sheets to the paper discharge roller pair consisting of paper discharge rollers 23 and 24 located further downstream and to a discharge stacking section 42. An upper guide plate 40 and a lower guide plate 41 guide the sheets conveyed by each roller pair. The lower guide plate 41 forms a wall surface between the sheets stacked on the sheet stacking tray 1 and the separation roller 9, and covers the upstream and downstream sides of the separation roller 9 so that part of the separation roller 9 is exposed to the conveying path.

[0020] An upstream sensor 31 is provided as a third sheet detection means on the upstream side of the conveying roller 14 in the conveying direction, and a downstream sensor 32 is provided on the downstream side in the conveying direction. The upstream sensor 31 and downstream sensor 32 detect the arrival of the leading or trailing edge of the sheet. The upstream sensor 31 and downstream sensor 32 are provided so as to be positioned at the center of the sheet width direction so that they can detect sheets of the minimum sheet width to be conveyed. When the leading or trailing edge of the sheet arrives, the pickup roller 5 and the feed roller 7 start or stop rotating. Details will be explained in the sheet feeding flow below.

[0021] The image reading device 200 includes a control unit 43 that controls the overall operation of the device. The control unit 43 is configured, for example, by one or more processors (CPUs).

[0022] <Pickup roller lifting mechanism> The pickup roller 5 has a lifting mechanism, and can be moved by a moving means between a take-in position where the pickup roller 5 comes into contact with a sheet to take in the sheet, and a retracted position where it is separated from the sheet. Figure 3 is a cross-sectional view of the area around the pickup roller 5, with Figure 3(a) showing the pickup roller 5 when moved to the retracted position and Figure 3(b) showing the pickup roller 5 when moved to the take-in position.

[0023] In Figure 3, the driving force of pickup motor 6 is transmitted to pickup motor drive gear 51. The driving force from pickup motor drive gear 51 is transmitted to pickup roller 5 via timing belt 54 and gear 53. Pickup motor drive gear 51, gear 53, and pickup roller 5 are attached to pickup roller frame 52. Pickup roller 5 is detachable from pickup roller frame 52 so that it can be replaced. Pickup roller frame 52 is oscillating with the center of pickup motor drive gear 51 as the rotation axis. Pickup lift motor 60 is a pulse motor that generates a force to oscillate pickup roller frame 52.

[0024] 3(a), pickup roller frame 52 is at its upper limit position, and frame detection sensor 56 detects that pickup roller frame 52 is in this position. Starting from the position where frame detection sensor 56 detects pickup roller frame 52, pickup lift motor 60 is driven a predetermined number of pulses to move pickup roller 5 to the pickup position shown in FIG.

[0025] Using the above-described lifting mechanism of the pickup roller 5, when a sheet is taken in from the sheet stacking table 1, the pickup roller 5 is moved to a sheet taking-in position, and when the pickup roller 5 has finished taking in the sheet up to the feeding roller 7 or when the sheet is being fed by a roller at a later stage, the pickup roller 5 is controlled by a control means to move to a retracted position away from the sheet taking-in position.

[0026] <Configuration for detecting a sheet near the feeding roller 7 and the separation roller 9> FIG. 4 is a partial cross-sectional view showing the schematic arrangement of components around an optical sensor provided near the feed roller 7 and the separation roller 9. As shown in FIG.

[0027] FIG. 5 is a partial cross-sectional view showing the layout of the components in the vicinity of the feeding roller 7 and the separation roller 9 as viewed from the upstream side in the conveying direction (the left side in FIG. 4).

[0028] Figures 4 and 5 show the feed roller 7, separation roller 9, upper guide plate 40, and lower guide plate 41 extracted from the components shown in Figure 1, as well as optical sensors that function as first sheet detection means 65 and second sheet detection means 66, which are sheet detection means for detecting the presence or absence of a sheet.

[0029] The first sheet detection means 65 and the second sheet detection means 66 are each composed of light-emitting sensors 62a, 62b that emit light including infrared light, light-receiving sensors 63a, 63b that receive the light, and light guides 61a, 61b that change the direction of the light emitted from the light-emitting sensors 62a, 62b and guide it to the light-receiving sensors 63a, 63b, respectively. The guided directions of the light emitted from the light-emitting sensors 62a, 62b are simply shown by dotted lines (optical axes R1a, R1b), and the light is guided to the light-receiving sensors 63a, 63b.

[0030] The light emitting sensor 62a and the light receiving sensor 63a are provided substantially perpendicular to the sheet conveying direction, and similarly, the light emitting sensor 62b and the light receiving sensor 63b are provided substantially perpendicular to the sheet conveying direction.

[0031] As shown in Fig. 5, first sheet detection means 65, which includes a light-emitting sensor 62a, a light-receiving sensor 63a, and a light guide 61a, is provided near the left end of the feed roller 7, which is the paper feed means, and the separation roller 9, which is the separation means. Second sheet detection means 66, which includes a light-emitting sensor 62b, a light-receiving sensor 63b, and a light guide 61b, is provided near the right end of the feed roller 7, which is the paper feed means, and the separation roller 9, which is the separation means. The first sheet detection means 65 and the second sheet detection means 66 are provided in positions approximately symmetrical with respect to the feed roller 7. Fig. 4 shows a separation roller holding member 44 that holds the rotation shaft of the separation roller 9. The sheet is fed from the left to the right in Fig. 4, and from the front to the back of the paper in Fig. 5.

[0032] The feed roller 7 has a first feed roller portion 7a and a second feed roller portion 7b made of a rubber material or the like attached to a feed wheel portion 7c, which is a rotational shaft extending in the sheet width direction. The separation roller 9 has a first separation roller portion 9a and a second separation roller portion 9b made of a rubber material or the like attached to a separation wheel portion 9c, which is a rotational shaft extending in the sheet width direction. The first feed roller portion 7a, the second feed roller portion 7b, the first separation roller portion 9a, and the second separation roller portion 9b each partially protrude into the conveyance path. The first feed roller portion 7a, the second feed roller portion 7b, the first separation roller portion 9a, and the second separation roller portion 9b are arranged approximately symmetrically with respect to the center in the width direction (left-right direction in FIG. 5) of the sheet to be fed. The distance between the first feeding roller unit 7a and the second feeding roller unit 7b, and the distance between the first separation roller unit 9a and the second separation roller unit 9b are set to be narrower than the minimum width of the sheet that can be fed.

[0033] The light emitting sensor 62a, which is a light emitting means, and the light receiving sensor 63a, which is a light receiving means, are mounted on a substrate 64a. The light emitting sensor 62b, which is a light emitting means, and the light receiving sensor 63b, which is a light receiving means, are mounted on a substrate 64b.

[0034] The light guides 61a and 61b are provided on the separation roller 9 side (lower side in FIGS. 4 and 5) across the transport path, and the substrates 64a and 64b are provided on the feed roller 7 side (upper side in FIGS. 4 and 5) across the transport path. The shapes of the light guides 61a and 61b are not limited to these.

[0035] As shown in Fig. 4, optical axis R1b is located downstream in the conveying direction from line 75 connecting the center of paper feed roller 7 and the center of separation roller 9. Similarly, optical axis R1a shown in Fig. 5 is located downstream in the conveying direction from line 75 connecting the center of paper feed roller 7 and the center of separation roller 9. The sheet can be detected by first sheet detection means 65 and second sheet detection means 66 only after the sheet is reliably nipped between feed roller 7 and separation roller 9.

[0036] Therefore, if the area (nip area) where the first feeding roller section 7a and the first separation roller section 9a contact is defined as the first nip area 50a, and the area (nip area) where the second feeding roller section 7b and the second separation roller section 9b contact is defined as the second nip area 50b, the light emitted from the light-emitting sensors 62a and 62b passes through a range (detection area) that is approximately the same as the first nip area 50a and the second nip area 50b in the conveying direction and in a direction perpendicular to the sheet surface.

[0037] When a sheet is present within the detection range, the light emitted from the light-emitting sensors 62a and 62b is attenuated as it passes through the sheet, and the amount of light detected by the light-receiving sensors 63a and 63b is significantly reduced compared to when there is no sheet. Therefore, by comparing the amount of light detected by the light-receiving sensors 63a and 63b with a predetermined threshold, it can be determined whether a sheet is present within the detection range (whether it is nipped). When both the first sheet detection means 65 and the second sheet detection means 66 detect a sheet, it is determined that the sheet is nipped.

[0038] If the subsequent sheet is within the detection range when feeding of the subsequent sheet begins, there is no need for pickup roller 5 to take in the subsequent sheet, so feed motor 8 is immediately driven to rotate feed roller 7 and feed the subsequent sheet. If the subsequent sheet is not within the detection range when feeding of the subsequent sheet begins, there is a need for pickup roller 5 to take in the sheet, so pickup roller 5 is moved to the take-in position to bring pickup roller 5 into contact with the subsequent sheet, and then pickup motor 6 is driven to rotate pickup roller 5 and take in the subsequent sheet.

[0039] 5, when a sheet narrower than the distance between the first sheet detection means 65 and the second sheet detection means 66 is fed, the sheet cannot be detected by the first sheet detection means 65 or the second sheet detection means 66. Furthermore, depending on how the sheet is installed, it may be possible for the sheet to be detected only by either the first sheet detection means 65 or the second sheet detection means 66. In such cases where the sheet cannot be detected by the first sheet detection means 65 or the second sheet detection means 66, the upstream sensor 31 provided downstream in the conveyance direction detects the leading edge of the sheet, and the pickup roller 5 is moved to a retracted position, so that the pickup roller 5 does not apply more pressure than necessary to the sheet, preventing double feeding or jamming of sheets.

[0040] <Sheet feeding control flow> The control of this embodiment will be described with reference to the flowchart in Fig. 6. The flowchart begins with sheets being stacked on the sheet stacking tray 1 and detected by the sheet stacking detection sensor 4. Furthermore, the sheet stacking tray 1 normally rises each time the number of stacked sheets decreases so that the topmost sheet is positioned at the take-in position, but this flowchart does not show the operation of lifting the sheet stacking tray 1.

[0041] First, the conveying motor 11 is driven to rotate the conveying rollers 14, 16, 18, and 20 (S101). Next, the feeding motor 8 is driven to rotate the feeding roller 7 (S102).

[0042] Next, in order to pick up the sheet with pickup roller 5, pickup lift motor 60 is driven to lower pickup roller 5 to the pick-up position shown in Fig. 3b, and then pickup motor 6 is driven to rotate pickup roller 5 (S103). When pickup roller 5 comes into contact with the sheet and the sheet's posture and load on the sheet are stabilized, pickup roller 5 is rotated, allowing the sheet to be picked up stably.

[0043] When the sheet picked up by the pickup roller 5 reaches the nip range between the feed roller 7 and the separation roller 9, the sheet is fed by the feed roller 7. The peripheral speed of the feed roller 7 is set faster than the peripheral speed of the pickup roller 5, and the sheet is pulled out by the feed roller 7.

[0044] Next, the first sheet detecting means 65 and the second sheet detecting means 66 detect whether or not a sheet is present in the nip range (S104).

[0045] When it is detected that the sheet is in the nip range (S104: YES), the pickup lift motor 60 is driven to raise the pickup roller 5 to the retracted position shown in FIG. 3a, so that the sheet does not come into contact with the pickup roller 5 and the rotation of the pickup roller 5 is stopped (S105).

[0046] When the sheet reaches the conveying rollers 14, 15, the sheet is conveyed by the conveying rollers 14, 15. The peripheral speed of the conveying rollers 14, 15 is set faster than the peripheral speed of the feeding roller 7, and the sheet is pulled out by the conveying rollers 14, 15.

[0047] Next, the downstream sensor 32, which is provided downstream of the conveying rollers 14 and 15 in the conveying direction, detects the presence or absence of a sheet, and determines whether the leading edge of the sheet has been detected (S106). If the downstream sensor 32 detects the leading edge of the sheet (S106: YES), the drive of the feed motor 8 is stopped, and the rotation of the feed roller 7 is stopped (S107). If the leading edge of the sheet is not detected (S106: NO), conveyance continues.

[0048] When the trailing edge of the sheet conveyed by the conveying rollers 14, 16, 18, and 20 passes through the nip range, the first sheet detecting means 65 and the second sheet detecting means 66 detect whether the leading edge of the succeeding sheet has entered the nip range (S108). If no succeeding sheet is detected in the nip range (S108: NO), the presence or absence of a sheet on the sheet stacking tray 1 is detected (S109).

[0049] If there is no sheet on the sheet stacking table 1 (S109: NO), the drive of the conveying motor 11 is stopped to stop the rotation of the conveying rollers 14, 16, 18, and 20 (S110), and the feeding operation is stopped.

[0050] If there is a sheet on the sheet stacking table 1 in S109 (S109: YES), the pickup roller 5 is lowered to the pickup position (S111).

[0051] An upstream sensor 31 provided upstream of the conveying rollers 14 and 15 in the conveying direction detects and determines whether the trailing edge of the sheet has passed (S112).

[0052] When the upstream sensor 31 detects the trailing edge of the sheet (S112: YES), the pickup roller 5 and the feed roller 7 start to rotate (S113), the subsequent sheet is fed, and the sheet taken in by the pickup roller 5 reaches the nip range between the feed roller 7 and the separation roller 9, and the process continues to S104. The subsequent feeding operation is the same as the operation when the preceding sheet was fed. If the upstream sensor 31 does not detect the trailing edge of the sheet (S112: NO), the sheet continues to be conveyed.

[0053] If it is detected in step S104 that the sheet is not in the nip range (S104: NO), that is, if the width of the sheet is narrower than the distance between the first sheet detection means 65 and the second sheet detection means 66, or if the sheet is set in a way that only one of the first sheet detection means 65 or the second sheet detection means 66 detects the sheet, the process proceeds to step S114.

[0054] When the upstream sensor 31 detects the leading edge of the sheet taken in by the pickup roller 5 (S114: YES), the pickup roller 5 is raised to the retracted position so that the sheet does not come into contact with the pickup roller 5 and the rotation of the pickup roller 5 is stopped (S115). When the upstream sensor 31 does not detect the leading edge of the sheet (S114: NO), the sheet continues to be conveyed.

[0055] After the sheet reaches the conveying rollers 14 and 15, it is determined whether the downstream sensor 32 has detected the leading edge of the sheet (S106). If the downstream sensor 32 detects the leading edge of the sheet (S106: YES), the process proceeds to step S107. The subsequent feeding operation is the same as the operation when feeding the preceding sheet described above.

[0056] In step S108, if it is detected that the succeeding sheet is in the nip range (S108: YES), the upstream sensor 31 detects and determines whether the trailing edge of the sheet has passed (S116). If the upstream sensor 31 detects the trailing edge of the sheet (S116: YES), the feed motor 8 is driven to rotate the feed roller 7 (S117), the succeeding sheet is taken in, and after the sheet reaches the conveyance rollers 14 and 15, it is determined whether the downstream sensor 32 has detected the leading edge of the sheet (S106). If the downstream sensor 32 detects the leading edge of the sheet, the process continues to S107. The subsequent feeding operation is the same as the operation when the preceding sheet was fed. If the upstream sensor 31 does not detect the trailing edge of the sheet (S116: NO), the sheet continues to be conveyed.

[0057] By using the above control flow, it is possible to determine whether the sheet is in the nip range between the feed roller 7 and the separation roller 9 at the stage when the pickup of the subsequent sheet begins, and the pickup roller 5 is brought into contact with the subsequent sheet only when the pickup operation by the pickup roller 5 is required, thereby ensuring that the subsequent sheet is fed.

[0058] <Second embodiment> Next, a sheet feeding device according to a second embodiment will be described. Explanation of parts common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described with reference to FIG.

[0059] In the first embodiment, a configuration was described in which a first sheet detection means 65 consisting of a light-emitting sensor 62a, a light-receiving sensor 63a, and a light guide 61a, and a second sheet detection means 66 consisting of a light-emitting sensor 62b, a light-receiving sensor 63b, and a light guide 61b are provided near both ends of the feed roller 7 and the separation roller 9.

[0060] In the second embodiment, a fourth sheet detection means 70 is provided, which is composed of a light emitting sensor 67 and a light guide 69 that changes the direction of light emitted from the light emitting sensor 67 and guides it to a light receiving sensor 68. The guided direction of the light emitted from the light emitting sensor 67 is simply shown by a dotted line (optical axis R2) as a representative, and the light is guided to the light receiving sensor 68.

[0061] As in the first embodiment, when the pickup of the subsequent sheet begins, it is determined whether the sheet is in the nip range between the feed roller 7 and the separation roller 9, and the pickup roller 5 is brought into contact with the subsequent sheet only when a pickup operation by the pickup roller 5 is required, thereby ensuring that the subsequent sheet is fed.

[0062] However, the shape of the light guide 69 is not limited to this.

[0063] <Third embodiment> Next, a sheet feeding device according to a third embodiment will be described. Explanation of parts common to the first embodiment will be omitted, and differences from the first embodiment will be mainly described with reference to FIG.

[0064] In the third embodiment, the first sheet detecting means 65 is composed of a light emitting sensor 62a and a light receiving sensor 63a, and the second sheet detecting means 66 is composed of a light emitting sensor 62b and a light receiving sensor 63b.

[0065] The light-emitting sensors 62a and 62b are provided on the feed roller 7 side (upper side in FIG. 8) across the conveyance path, and the light-receiving sensors 63a and 63b are provided on the separation roller 9 side (lower side in FIG. 8) across the conveyance path. The directions in which light emitted from the light-emitting sensors 62a and 62b is guided are simply shown by dotted lines (optical axes R1a and R1b), and the light is guided to the light-receiving sensors 63a and 63b.

[0066] As in the first embodiment, by determining whether the sheet is in the nip range between the feed roller 7 and the separation roller 9 at the stage when the pickup of the subsequent sheet begins, the pickup roller 5 is brought into contact with the subsequent sheet only when a pickup operation by the pickup roller 5 is required, thereby ensuring that the subsequent sheet is fed.

[0067] Furthermore, a light guide may be used to separate the light emitting sensors 62a and 62b from the light receiving sensors 63a and 63b.

[0068] The first sheet detection means 65, second sheet detection means 66, and fourth sheet detection means 70 of the present invention may be installed at an angle to each other, rather than having the light receiving sensor and light emitting sensor or light guide installed in a straight line as described above. [Explanation of symbols]

[0069] 1 seat loading platform 1a Sheet loading surface 2 Loading platform drive motor 3 Sheet detection sensor 4 Sheet stacking detection sensor 5 Pickup roller 6 Pickup motor 7 Feeding roller 7a 1st feeding roller section 7b Second feeding roller section 7c Feeding wheel section 8 Feeding motor 9 Separation roller 9a First separation roller section 9b Second separation roller section 9c Separation wheel section 10 Separation motor 11 Transport motor 12, 13 Image reading sensor 14~21 Conveyor rollers 22 Resist Clutch 23, 24 Paper ejection roller 30 Double feed detection sensor 31 Upstream sensor 32 Downstream sensor 36 Light-emitting substrate 37 Photoreceptor board 38 Reflective photoelectric sensor 40 Upper guide plate 41 Lower guide plate 42 Discharge loading section 43 Control Unit 44 Separation roller holding member 45 Separate cover 50a 1st nip range 50b Second nip range 60 Pickup lift motor 61a, 61b light guide 62a, 62b Light-emitting sensors 63a, 63b Light receiving sensor 64 boards 65 First sheet detection means 66 Second sheet detection means 67 Light-emitting sensor 68 Light receiving sensor 69 Light guide 70 Fourth sheet detection means 101 Sheet intake section 200 Image reader

Claims

1. a sheet loading table on which sheets are loaded; a take-in unit that takes in the sheets stacked on the sheet stacking table into the apparatus body; a feeding means for feeding the sheet taken in by the taking-in means; a separating means for contacting the feeding means and separating a sheet to be fed from the plurality of sheets; a sheet detecting means for detecting the presence or absence of a sheet between the feeding means and the separating means; The sheet feeding device is characterized in that the sheet taking-in operation of the sheet taking-in means is controlled based on the detection result by the sheet detecting means.

2. the feeding means has a feeding roller unit having a rotation shaft extending in the sheet width direction, the separating means includes a separating roller unit having a rotation shaft extending in the sheet width direction, The sheet feeding device of claim 1, wherein the feeding roller unit and the separation roller unit are configured to come into contact with each other to form a nip range, and the range in which the sheet detection means detects the presence or absence of the sheet is within the nip range in the sheet transport direction, and is downstream of the line connecting the center of the rotation axis of the feeding roller unit and the center of the rotation axis of the separation roller unit.

3. a moving means for moving the take-in means between a take-in position where the take-in means contacts the sheets stacked on the sheet stacking table and a retracted position where the take-in means is spaced apart from the sheets; a control means for controlling the feeding means and the moving means; Equipped with 2. The sheet feeding device according to claim 1, wherein the control means controls the moving means so that the take-up means moves to the retracted position when the sheet detection means detects a sheet, and the take-up means moves to the take-up position when the sheet detection means no longer detects a sheet.

4. 4. The sheet feeding device according to claim 1, wherein the sheet detecting means comprises a first sheet detecting means and a second sheet detecting means located near both ends of the feeding means and the separating means.

5. a third sheet detecting means for detecting the presence or absence of a sheet being conveyed, the third sheet detecting means being disposed downstream of the feeding means; The sheet feeding device according to claim 4, characterized in that when feeding a sheet whose width is narrower than the distance between the first sheet detection means and the second sheet detection means, when the third sheet detection means detects the leading edge of the sheet, the take-up means moves to an take-up position in contact with the sheet stacked on the sheet stacking tray and to a retracted position away from the sheet.

6. the first sheet detecting means and the second sheet detecting means each include a light emitting means, a light guide that changes the direction of the light emitted from the light emitting means, and a light receiving means that receives the light that has been changed in direction by the light guide; 5. The sheet feeding apparatus according to claim 4, wherein the light emitting means and the light receiving means are disposed substantially perpendicular to the conveying direction.

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