Media transport device and image reading device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SEIKO EPSON CORP
- Filing Date
- 2025-01-22
- Publication Date
- 2026-08-03
Smart Images
Figure 2026125459000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a medium conveyance device and an image reading device.
Background Art
[0002] Conventionally, various medium conveyance devices capable of feeding a medium to a conveyance unit have been used. For example, Patent Document 1 discloses a medium conveyance device that feeds a medium from a feeding unit to a conveyance unit and can convey the medium by the conveyance unit.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] The medium conveyance device disclosed in Patent Document 1 is configured to suppress skewing (oblique conveyance) of the medium when feeding the medium from the feeding unit to the conveyance unit. However, in conventional medium conveyance devices capable of feeding a medium to a conveyance unit, it has been difficult to improve skew correction performance without degrading the conveyance performance of the medium. For example, when the distance between sensors is wide, skew of a narrow medium may not be detected. Also, in the medium conveyance device of Patent Document 1, since the center sensor is arranged downstream of the feeding roller, paper dust is likely to adhere to the center sensor, and the detection accuracy of the medium may decrease, and it is necessary to consider the arrangement of the sensors.
Means for Solving the Problems
[0005] The media transport apparatus of the present invention, which solves the above problems, comprises: a transport unit for transporting the medium downstream in the transport direction of the medium, comprising a first transport roller and a second transport roller that rotates together with the first transport roller, provided at intervals in the width direction intersecting the transport direction; a separation unit for separating the medium transported together with the transport unit, comprising a first separation roller positioned opposite to the first transport roller and a second separation roller positioned opposite to the second transport roller; a detection unit for detecting the skew of the medium transported from the transport unit; and a unit that rotates the first transport roller and the second transport roller while adjusting their respective rotational speeds based on the skew state of the medium detected by the detection unit. The detection unit comprises a control unit and a detection unit, wherein a first sensor, a second sensor, and a third sensor are arranged at intervals in the width direction, the first sensor is located downstream in the transport direction from the nip position between the first feed roller and the first separation roller and the nip position between the second feed roller and the second separation roller, and is located between the first feed roller and the second feed roller in the width direction, and is located at a position that overlaps with the first feed roller and the second feed roller in the width direction, the second sensor is located to one side of the first sensor in the width direction, and the third sensor is located to the other side of the first sensor in the width direction. [Brief explanation of the drawing]
[0006] [Figure 1] A side view of the image reading device of Embodiment 1 of the present invention. [Figure 2] Front cross-sectional view showing the separation section of the image reading device in Figure 1. [Figure 3] Figure 1 is a perspective view showing the separation section of the image reading device, with a portion of it depicted in perspective. [Figure 4] Figure 1 is a front cross-sectional view showing the feeding and separation sections of the image reading device. [Figure 5] A perspective view showing the feeding and separation sections of the image reading device shown in Figure 1. [Figure 6]This diagram illustrates the arrangement of the detection unit of the image reading device in Figure 1 relative to the feeding unit. [Figure 7] This diagram illustrates the arrangement of the first to third sensors, which are part of the detection unit of the image reading device shown in Figure 1, relative to the feeding unit and the transport roller pair. [Figure 8] This diagram illustrates the arrangement of the second and third sensors, which are part of the detection unit of the image reading device shown in Figure 1, relative to the feeding unit and the pair of transport rollers. [Figure 9] This diagram illustrates the arrangement of the first sensor, part of the detection unit of the image reading device shown in Figure 1, relative to the feeding unit. [Figure 10] A front cross-sectional view showing the separation section of the image reading device of Embodiment 2 of the present invention. [Figure 11] A front cross-sectional view showing the separation section of the image reading device of Embodiment 3 of the present invention. [Figure 12] A front cross-sectional view showing the separation section of the image reading device of Embodiment 4 of the present invention. [Modes for carrying out the invention]
[0007] First, the present invention will be described in general terms. A media transport device according to a first aspect of the present invention for solving the above problems is a transport unit for transporting the media downstream in the transport direction of the media, comprising: a first transport roller and a second transport roller that rotates together with the first transport roller, provided at intervals in a width direction intersecting the transport direction; a separation unit for separating the media that is transported together with the transport unit, comprising: a first separation roller positioned opposite to the first transport roller and a second separation roller positioned opposite to the second transport roller; a detection unit for detecting the skew of the media transported from the transport unit; and a unit that adjusts the rotation speed of the first transport roller and the second transport roller respectively based on the skew state of the media detected by the detection unit. The detection unit comprises a control unit, wherein a first sensor, a second sensor, and a third sensor are arranged at intervals in the width direction, the first sensor is located downstream in the transport direction from the nip position between the first feed roller and the first separation roller and the nip position between the second feed roller and the second separation roller, and is located between the first feed roller and the second feed roller in the width direction, and is located at a position that overlaps with the first feed roller and the second feed roller in the width direction, the second sensor is located to one side of the first sensor in the width direction, and the third sensor is located to the other side of the first sensor in the width direction.
[0008] In this embodiment, the first sensor is positioned downstream in the transport direction from the nip position between the first feed roller and the first separation roller, and from the nip position between the second feed roller and the second separation roller, and is positioned between the first feed roller and the second feed roller in the width direction, and overlapping with the first feed roller and the second feed roller in the width direction. The second sensor is positioned to one side of the first sensor in the width direction, and the third sensor is positioned to the other side of the first sensor in the width direction. With this configuration, the adhesion of paper dust to the first sensor is suppressed, which suppresses a decrease in the accuracy of skew detection, and the timing of skew detection by the first sensor can be advanced, allowing for early skew correction. Therefore, skew correction performance can be improved without reducing the transportability of the media.
[0009] A second aspect of the media transport device of the present invention is an aspect dependent on the first aspect, wherein the separation section includes a first torque limiter, the first separation roller is capable of rotating together with the first feeding roller when a torque greater than a first torque value derived from the limit torque value of the first torque limiter is applied, the second separation roller is capable of both rotating together with the first separation roller and rotating independently of the first separation roller, and the first torque value is the torque value applied to the first separation roller when the limit torque value is applied to the first torque limiter.
[0010] According to this embodiment, the separation unit is equipped with a first torque limiter, and the first separation roller can rotate together with the first feed roller when a torque greater than a first torque value derived from the limit torque value of the first torque limiter is applied, and the second separation roller can both rotate together with the first separation roller and rotate independently of the first separation roller. With such a configuration, the diagonal correction capability can be improved.
[0011] A third aspect of the present invention is a media transport device that is dependent on the first or second aspect, characterized in that the second sensor and the third sensor are positioned downstream of the first sensor in the transport direction.
[0012] In this embodiment, the second and third sensors are positioned downstream of the first sensor in the transport direction. This configuration allows the first sensor to detect skew at an earlier timing, and by combining this with the detection by the second and third sensors, accurate skew detection can be achieved.
[0013] A fourth aspect of the present invention is a media transport device that is dependent on any one of the first to third aspects, characterized in that the distance between the second sensor and the third sensor in the width direction is narrower than the minimum width of the usable media.
[0014] In this embodiment, the distance between the second sensor and the third sensor in the width direction is narrower than the minimum width of the usable medium. With this configuration, even if the medium with the minimum width is skewed, the skew can be reliably detected.
[0015] The media conveyance device according to the fifth aspect of the present invention is an aspect subordinate to any one of the first to fourth aspects, and includes a pair of conveyance rollers disposed downstream in the conveyance direction from the feeding unit. The second feeding roller is disposed on the other side of the first feeding roller, the third sensor is disposed on the other side of the second sensor, and the first sensor and the third sensor are disposed on or upstream in the conveyance direction from the first virtual line connecting the one-side end of the nip position of the first feeding roller and the other-side end of the nip position of the pair of conveyance rollers. With respect to the second virtual line connecting the other-side end of the nip position of the second feeding roller and the one-side end of the nip position of the pair of conveyance rollers, the first sensor and the second sensor are disposed on the second virtual line or upstream in the conveyance direction from the second virtual line.
[0016] According to this aspect, the second feeding roller is disposed on the other side of the first feeding roller, the third sensor is disposed on the other side of the second sensor, and the first sensor and the third sensor are disposed on or upstream in the conveyance direction from the first virtual line connecting the one-side end of the nip position of the first feeding roller and the other-side end of the nip position of the pair of conveyance rollers. With respect to the second virtual line connecting the other-side end of the nip position of the second feeding roller and the one-side end of the nip position of the pair of conveyance rollers, the first sensor and the second sensor are disposed on the second virtual line or upstream in the conveyance direction from the second virtual line. With such a configuration, skew can be detected before the media is nipped by the pair of conveyance rollers.
[0017] The media conveyance device according to the sixth aspect of the present invention is an aspect subordinate to any one of the first to fifth aspects, wherein the second feed roller is disposed on the other side of the first feed roller, the third sensor is disposed on the other side of the second sensor, and the third sensor is disposed on or upstream of the third virtual line in the conveyance direction with respect to the third virtual line connecting the one-side end of the nip position of the first feed roller and the first sensor, and the second sensor is disposed on or upstream of the fourth virtual line in the conveyance direction with respect to the fourth virtual line connecting the other-side end of the nip position of the second feed roller and the first sensor.
[0018] According to this aspect, the second feed roller is disposed on the other side of the first feed roller, the third sensor is disposed on the other side of the second sensor, and the third sensor is disposed on or upstream of the third virtual line in the conveyance direction with respect to the third virtual line connecting the one-side end of the nip position of the first feed roller and the first sensor, and the second sensor is disposed on or upstream of the fourth virtual line in the conveyance direction with respect to the fourth virtual line connecting the other-side end of the nip position of the second feed roller and the first sensor. With such a configuration, skew can be detected before the medium is nipped by the pair of conveyance rollers.
[0019] The media conveyance device according to the seventh aspect of the present invention is an aspect subordinate to any one of the first to sixth aspects, wherein the control unit calculates a skew amount from a time difference when the medium passes through the first sensor and the second sensor or the first sensor and the third sensor, or a drive amount difference between the first feed roller and the second feed roller, and adjusts the rotational speed of each of the first feed roller and the second feed roller according to the calculated skew amount.
[0020] According to this embodiment, the amount of skew is calculated from the time difference in which the medium passes through the first sensor and the second sensor or the first sensor and the third sensor, or from the difference in the amount of drive between the first feed roller and the second feed roller, and the rotational speed of the first feed roller and the second feed roller are adjusted according to the calculated amount of skew. With this configuration, the skew can be suitably corrected.
[0021] An image reading device according to the eighth aspect of the present invention is characterized by comprising one of the first to seventh media transport devices and a reading unit for reading an image of the media.
[0022] According to this embodiment, it is possible to read images from a medium that has been skew-corrected with high accuracy.
[0023] An image reading device according to a ninth aspect of the present invention is an aspect dependent on the eighth aspect, wherein the reading unit is located downstream of the detection unit in the transport direction, and the control unit calculates a skew amount from the image data read by the reading unit and adjusts the rotational speed of the first feed roller and the second feed roller according to the calculated skew amount.
[0024] According to this embodiment, the reading unit calculates the amount of skew from the image data it reads, and adjusts the rotational speed of the first feed roller and the second feed roller according to the calculated amount of skew. With this configuration, images of a medium that have been skew-corrected with particularly high accuracy can be read by feedback control.
[0025] [Example 1] Hereinafter, an embodiment of the image reading device 1 as an example of a media transport device according to the present invention will be described with reference to Figures 1 to 10. First, the outline of the image reading device 1 of Embodiment 1 of the present invention will be described with reference to Figure 1. In the following description, the three mutually orthogonal axes will be referred to as the X axis, Y axis, and Z axis, as shown in each figure. The direction indicated by the arrows on the three axes (X, Y, Z) is the + direction for each direction, and the opposite is the - direction. The Z axis direction corresponds to the vertical direction, that is, the direction in which gravity acts, with the +Z direction indicating vertically upward and the -Z direction indicating vertically downward. The X axis direction and Y axis direction correspond to the horizontal direction, of which the X axis direction corresponds to the width direction. The +Y direction indicates the front direction of the device, and the -Y direction indicates the rear direction of the device. The +X direction indicates the right direction of the device, and the -X direction indicates the left direction of the device.
[0026] The image reading device 1 in this embodiment is a document scanner capable of reading an image formed on a medium 2. Here, the image formed on the medium 2 refers to something that is visually recorded on the medium 2, such as characters, figures, tables, pictures, photographs, etc. The medium is not limited to sheets, but also includes cards, booklets, etc. The image reading device 1 of the present invention is not limited to a scanner, but may also be a copier, facsimile machine, etc.
[0027] As shown in Figure 1, the image reading device 1 can be considered a media transport device that transports the medium 2 along the transport path 3 in the transport direction F, and is equipped with a reading unit 5 that reads the image of the transported medium 2. The image reading device 1 is equipped with two reading units 51 and 22 as the reading unit 5 that reads the image of the medium 2. The first reading unit 51 is located on the upper side of the transport path 3 and reads the image of the first surface of the medium 2. The second reading unit 52 is located on the lower side of the transport path 3 and reads the image of the second surface, which is opposite to the first surface. The reading unit 5 is composed of, for example, a CIS (Contact Image Sensor) type sensor or a CCD (Charge Coupled Device) type sensor.
[0028] The image reading device 1 includes a transport unit 6 that transports the medium 2 along the transport path 3 in the transport direction F. The transport unit 6 of the image reading device 1 includes a first transport roller pair 7 located upstream of the first reading unit 51, a second transport roller pair 8 located upstream of the second reading unit 52 which is located downstream of the first reading unit 51, and a third transport roller pair 9 located downstream of the second reading unit 52. The first transport roller pair 7, the second transport roller pair 8, and the third transport roller pair 9 are composed of pairs of driven rollers and driven rollers that rotate by the power of a drive source such as a motor (not shown).
[0029] Upstream of the first transport roller pair 7 in the transport direction F, a feeding unit 10 and a separation unit 11, which will be described in detail later, are located. The feeding unit 10 is equipped with two feeding rollers that rotate using the power of a motor M shown in Figures 4 and 5 as a drive source, and transports the medium 2 toward the transport direction F. The separation unit 11 is equipped with a torque limiter and two separation rollers that rotate using the power of a motor M shown in Figure 2 as a drive source, and is capable of separating multiple sheets of medium 2 into a single sheet. Here, each separation roller rotates in a direction that sends the medium 2 toward the upstream side (+Y direction) of the transport direction F using the power of the motor M, but when a torque exceeding a set value is applied to the torque limiter, it rotates in a direction that sends the medium 2 toward the downstream side (-Y direction) of the transport direction F. Upstream of the separation unit 11 in the transport direction F, a pick roller 12 is located. The pick roller 12 is a drive roller that rotates using the power of a drive source (not shown), and picks up the medium 2 and sends it toward the transport direction F.
[0030] The image reading device 1 is provided with a U-turn path 14 downstream of the straight path 13 from the feeding unit 10 to the third transport roller pair 9, that is, downstream of the third transport roller pair 9. The U-turn path 14 contains the fourth transport roller pair 15, the fifth transport roller pair 16, and the discharge roller pair 17, which are transport units 6, arranged in this order along the transport direction F. The fourth transport roller pair 15, the fifth transport roller pair 16, and the discharge roller pair 17 are also composed of pairs of driven rollers and driven rollers that rotate with power from a drive source (not shown). The discharge tray 19 that receives the medium 2 discharged from the discharge roller pair 17 in the discharge direction 18 is positioned above the straight path 13 to achieve a compact design.
[0031] The medium 2 on the feeding tray 21 is picked up by the pick roller 12 and sent in the transport direction F. The feeding tray 21 is configured to move up and down by power from a drive source (not shown). When sending the medium 2 set on the feeding tray 21 in the transport direction F, the feeding tray 21 is first moved upward (+Z direction) by power transmitted from the drive source (not shown), and stops with the medium 2 at the top in contact with the pick roller 12. In this state, the pick roller 12 rotates, sending the medium 2 in the transport direction F, and the leading edge of the medium 2 reaches the nip position of the roller pair of the feeding section 10 and the separation section 11.
[0032] If multiple sheets of medium 2 are being fed at once, the separation unit 11 separates them into one sheet, and that single sheet is transported in the transport direction F by the first transport roller pair 7, and the first reading unit 51 reads the image of the first surface of medium 2. The medium 2 that has been read by the first reading unit 51 is transported by the second transport roller pair 8, and the second reading unit 52 reads the image of the second surface of medium 2, which is opposite to the first surface.
[0033] The control unit 22 controls the driving of each drive source and the reading operation of the reading unit 5 in accordance with the transport of the medium 2. The control unit 22 is equipped with a CPU, ROM, and RAM (not shown). The CPU performs various calculations according to the program stored in the ROM and controls the operation of the entire image reading device 1. As an example of a storage means, flash ROM, which is a non-volatile memory that can be read and written to, can be preferably used as ROM. Various information is temporarily stored in RAM, which is another example of a storage means.
[0034] The image reading device 1 includes a media discharge device 30. The media discharge device 30 includes a pair of discharge rollers 17 as a discharge section 31 for discharging the media 2, and a discharge tray 19 having a mounting surface 32 on which the media 2 discharged from the discharge section 31 in the discharge direction 18 is placed. The discharge tray 19 is configured to be expandable and contractible in the direction along the mounting surface 32. That is, the discharge tray 19 is configured to extend the length of the mounting surface 32. The media discharge device 30 also includes an expansion / contraction changing section 33 for expanding and contracting the discharge tray 19. The expansion / contraction changing section 33 is configured to expand or contract the discharge tray 19 according to the size of the media 2.
[0035] In this embodiment, the discharge tray 19 is configured to be rotatable in the vertical direction with its base end 34 as a pivot point 35. That is, the discharge tray 19 is structured so that it can be rotated by the user lifting its tip 37 upward. The discharge tray 19 comprises a base tray 38 and an auxiliary tray 39 that is movable in the extension and retraction direction relative to the base tray 38. A projection is provided at the base end of the auxiliary tray 39. The projection is a plate-shaped member that protrudes downward from the auxiliary tray 39.
[0036] The extension / retraction section 33 is configured to extend the discharge tray 19 in conjunction with the rotation of the discharge tray 19. When the tip 37 of the discharge tray 19 rotates up and down with the base end 34 as the pivot point 35, the other end 44 slides in the extension / retraction direction, which is along the mounting surface 32, while connected to the base tray 38.
[0037] The details of the feeding unit 10 and the separation unit 11 will be described below with reference to Figures 2 to 5. Here, the image reading device 1 of this embodiment can be considered as a medium transport device comprising a feeding unit 10 that feeds the medium 2 downstream in the transport direction F of the medium 2, and a separation unit 11 that separates the medium 2 that is fed together with the feeding unit 10.
[0038] The feeding unit 10, as shown in Figure 4 and other figures, includes a first feeding roller 101 and a second feeding roller 102 that rotate together with the first feeding roller 101, which are spaced apart in the width direction (X-axis direction) intersecting the transport direction F. The separation unit 11, as shown in Figures 2 to 5, includes a first torque limiter 211. Furthermore, it includes a first separation roller 201 positioned opposite the first feeding roller 101 and capable of rotating together with the first feeding roller 101 when a torque greater than a first torque value derived from the limit torque value of the first torque limiter 211 is applied, and a second separation roller 202 positioned opposite the second feeding roller 102 and capable of both rotating together with the first separation roller 201 and rotating independently of the first separation roller 201.
[0039] In detail, if the limit torque value of the first torque limiter 211 is T, then the "first torque value derived from the limit torque value of the first torque limiter 211" applied to the first separation roller 201 is 1 / 2T. This is because, as shown in Figure 2, the first torque limiter 211 is connected to both the first separation roller 201 and the second separation roller 202, and the torque applied to the first torque limiter 211 is the sum of the torques of the first separation roller 201 and the second separation roller 202. For example, if a torque of 1 / 2T, which is the first torque value, is applied to the first separation roller 201, then 1 / 2T of torque is applied to the first torque limiter 211 from both the first separation roller 201 and the second separation roller 202. In other words, the "first torque value derived from the limit torque value of the first torque limiter 211" corresponds to the torque value of the first separation roller 201 when the limit torque value is applied to the first torque limiter 211.
[0040] In this embodiment, the image reading device 1, as shown in Figures 6 to 9, includes a detection unit 300 that detects the skew of the medium 2 fed from the feeding unit 10. The control unit 22 can then rotate the first feeding roller 101 and the second feeding roller 102 while adjusting their respective rotation speeds based on the skew state of the medium 2 detected by the detection unit 300.
[0041] Furthermore, as shown in Figure 2 and other figures, the separation unit 11 is equipped with a second torque limiter 212 that connects the first separation roller 201 and the second separation roller 202 in the width direction (X-axis direction). The limit torque value of the second torque limiter 212 is a second torque value that is smaller than the first torque value. The second separation roller 202 can rotate together with the second feed roller 102 when a torque greater than the second torque value is applied. In other words, the first torque limiter 211 defines the overall torque of the first separation roller 201 and the second separation roller 202. To put it another way, it defines whether or not they rotate together with the first feed roller 101 and the second feed roller 102. On the other hand, the second torque limiter 212 defines whether the first separation roller 201 and the second separation roller 202 rotate together or separately.
[0042] Here, the second torque value is greater than the torque difference between the torque applied to the first separation roller 201 and the torque applied to the second separation roller 202 that occurs when there is no difference in rotational speed between the first feed roller 101 and the second feed roller 102. Furthermore, the second torque value is less than the torque difference between the torque applied to the first separation roller 201 and the torque applied to the second separation roller 202 that occurs when there is a difference in rotational speed between the first feed roller 101 and the second feed roller 102.
[0043] Thus, in the image reading device 1 of this embodiment, since the second torque value of the second torque limiter 212 is smaller than the first torque value derived from the limit torque value of the first torque limiter 211, the separation function of the double-feeding medium 2 can be fully performed. Furthermore, since the second torque value is larger than the torque difference between the first separation roller 201 and the second separation roller 202 that occurs when there is no difference in rotational speed between the first feeding roller 101 and the second feeding roller 102, the straightness of the conveyance is improved by the restraining force of the second torque value. Moreover, since the second torque value is smaller than the torque difference between the first separation roller 201 and the second separation roller 202 that occurs when there is a difference in rotational speed between the first feeding roller 101 and the second feeding roller 102, the responsiveness of the first separation roller 201 and the second separation roller 202 due to the rotation of the first feeding roller 101 and the second feeding roller 102 is improved, and skew can be suppressed. Therefore, the image reading device 1 of this embodiment can improve skew correction performance without reducing the transportability of the medium 2.
[0044] In other words, by using a second torque limiter 212 between the first separation roller 201 and the second separation roller 202, when the medium 2 is moving in a straight line and not at an angle, the torque generated in the first separation roller 201 and the second separation roller 202 is less than or equal to the second torque value, so the first separation roller 201 and the second separation roller 202 rotate together. Then, when the medium 2 moves at an angle and the angle is corrected, the torque generated in the first separation roller 201 and the second separation roller 202 exceeds the second torque value, so the left and right first separation roller 201 and second separation roller 202 can rotate independently. That is, the ability to correct the angle can be improved without impairing straight-line movement.
[0045] As shown in Figures 2 to 5, the separation unit 11 is equipped with a differential gear 220 that connects the first separation roller 201 and the second separation roller 202. This configuration allows the image reading device 1 of this embodiment to rotate the first separation roller 201 and the second separation roller 202 independently without complicating the device configuration. Therefore, the ability to correct diagonal deviation when the first feed roller 101 and the second feed roller 102 are driven independently is improved. Furthermore, by using the differential gear 220, the load for diagonal deviation correction is the same for left and right rotation, thus eliminating left-right differences.
[0046] Here, as shown in Figure 2, the first separation roller 201 is fixed to the rotating shaft 231. A gear 232 that meshes with a gear 233 provided on the rotating shaft 234 of the motor M is fixed to the rotating shaft 231, and the first separation roller 201 rotates as the rotating shaft 234 of the motor M rotates. However, since the first separation roller 201 is connected to the first torque limiter 211, if a force greater than the first torque value is applied from the first feed roller 101, the first separation roller 201 rotates together with the first feed roller 101.
[0047] As shown in Figures 2 and 3, the differential gear 220 comprises a case 221 connected to the first torque limiter 211, a conical gear 222 fixed to the rotation axis 231 of the first separation roller 201 and the second separation roller 202, a pinion gear 223 that meshes with the conical gear 222, and a conical gear 224 that meshes with the pinion gear 223 and is fixed to the second separation roller 202. The first separation roller 201 and the second separation roller 202 are both connected to the second torque limiter 212. With this configuration, the second separation roller 202 will rotate together with the second feed roller 102 even if the force applied from the second feed roller 102 is less than the first torque value, if the force applied from the second feed roller 102 is greater than the second torque value. In other words, if the torque value of the first torque limiter 211 is T, then even if the force applied is less than the first torque value of 1 / 2T, if the force is greater than the second torque value (for example, 1 / 4T), the second separation roller 202 will rotate together with the second feed roller 102.
[0048] From another perspective, the separation unit 11 uses a differential gear 220 to enable the left and right separation rollers (first separation roller 201 and second separation roller 202) to rotate independently when viewed from the transport direction F. The first separation roller 201 is driven by a bevel-toothed conical gear 222 that rotates around the rotation axis 231, and the second separation roller 202 is driven by a bevel-toothed conical gear 224 that rotates around the rotation axis 231. Both the conical gears 222 and 224 are connected by a bevel-toothed pinion gear 223, which is rotatable around an axis perpendicular to the rotation axis 231, and the rotation axis of the pinion gear 223 is held by a case 221 that rotates in the direction of rotation of the rotation axis 231. The separation force in the separation unit 11 is generated when the case 221 is connected to the first torque limiter 211.
[0049] Furthermore, the left and right separation rollers (first separation roller 201 and second separation roller 202) as viewed from the transport direction F are connected by a second torque limiter 212. The second torque value of the second torque limiter 212 is smaller than the first torque value. The second torque value is set to be greater than the torque difference between the left and right separation rollers that occurs when there is no difference in rotational speed between the left and right feed rollers (first feed roller 101 and second feed roller 102), and smaller than the torque difference between the left and right separation rollers that occurs when there is a difference in rotational speed between the left and right feed rollers.
[0050] By using a differential gear 220 in the separation unit 11, the load for diagonal correction in left and right rotations becomes the same, making it possible to improve the accuracy of diagonal correction by the left and right separation rollers. And, to reiterate, by using a second torque limiter 212 between the separation rollers, when the transport of the medium 2 moves in a straight line along the transport direction F, the torque generated in the left and right separation rollers is less than or equal to the second torque value, so the left and right separation rollers rotate as a single unit. On the other hand, when diagonal correction is performed when skew occurs due to the transport of the medium 2 being at an angle to the transport direction F, the torque generated in the left and right separation rollers exceeds the second torque value, so the left and right separation rollers rotate independently. In other words, by using a differential gear 220 in the separation unit 11, it is possible to improve the diagonal correction capability without impairing straight-line movement.
[0051] Furthermore, in the separation unit 11, the first separation roller 201 is connected to the first torque limiter 211, and the second separation roller 202 is also connected to the first torque limiter 211 via a differential gear 220 through a separate connection path. In other words, the first separation roller 201 and the second separation roller 202 each have a torque value that is an equal division of the torque value applied to the first torque limiter 211. With this configuration, the image reading device 1 of this embodiment makes it possible to rotate the first separation roller 201 and the second separation roller 202 independently without complicating the device configuration.
[0052] Furthermore, as shown in Figures 4 and 5, the image reading device 1 of this embodiment includes, as motor M, a first drive source M1 that drives the first feed roller 101 via the gear train 111, and a second drive source M2 that drives the second feed roller 102 via the gear train 112. In this way, by driving the first feed roller 101 and the second feed roller 102 with separate drive sources (motors M), skew correction control can be easily facilitated.
[0053] Next, the specific arrangement of the detection unit 300 for detecting the skew correction of the medium 2 will be described with reference to Figures 6 to 9. As shown in Figures 6 to 9, the image reading device 1 of this embodiment includes a first sensor 301, a second sensor 302, and a third sensor 303 as the detection unit 300. The first sensor 301, the second sensor 302, and the third sensor 303 are each spaced apart in the width direction (X-axis direction).
[0054] Here, as shown in Figure 6, the first sensor 301 is positioned at position P11 downstream in the transport direction F from position P1, which is the nip position between the first feed roller 101 and the first separation roller 201, and position P2, which is the nip position between the second feed roller 102 and the second separation roller 202. Furthermore, the first sensor 301 is positioned at position P11 which is within the range L1 between the first feed roller 101 and the second feed roller 102 in the X-axis direction, and also within the range L2 that overlaps the first feed roller 101 and the second feed roller 102 in the X-axis direction. On the other hand, the second sensor 302 is positioned at position P12 to one side (+X direction side) of the first sensor 301 in the X-axis direction, and the third sensor 303 is positioned at position P13 to the other side (-X direction side) of the first sensor 301 in the X-axis direction.
[0055] This configuration suppresses the adhesion of foreign matter such as paper dust from the transported medium 2 to the first sensor 301, thereby suppressing a decrease in the accuracy of skew detection. Furthermore, the first sensor 301 allows for earlier detection of skew, enabling early skew correction. Therefore, the image reading device 1 of this embodiment can improve skew correction performance without reducing the transportability of the medium 2. While skew detection is possible even without the first sensor 301 if the second sensor 302 and third sensor 303 are present, the presence of the first sensor 301 enables earlier detection of skew.
[0056] Furthermore, in this embodiment, as shown in Figures 6 to 9, the second sensor 302 and the third sensor 303 are positioned at positions P12 and P13 downstream of the first sensor 301 in the transport direction F. With this configuration, the image reading device 1 of this embodiment can detect skew at an early stage using the first sensor 301, and by combining this with the detection by the second sensor 302 and the third sensor 303, accurate skew detection can be achieved.
[0057] Furthermore, as shown in Figure 6, the distance L3 between the second sensor 302 and the third sensor 303 in the width direction (X-axis direction) of the image reading device 1 of this embodiment is narrower than the minimum width L4 of the usable medium 2. With this configuration, the image reading device 1 of this embodiment can reliably detect skew even when the medium 2 with the minimum width is skewed. It is preferable that the distance L3 between the second sensor 302 and the third sensor 303 is less than 51 mm, for example. However, there are no particular limitations on the distance L3 between the second sensor 302 and the third sensor 303 in the width direction (X-axis direction), and for example, they may be provided inward or outward in the width direction (X-axis direction) of the first feed roller 101 and the second feed roller 102.
[0058] As described above, the image reading device 1 of this embodiment includes a first transport roller pair 7 positioned downstream of the feed unit 10 in the transport direction F. Here, as shown in Figure 7, the second feed roller 102 is positioned on the other side (-X direction side) of the first feed roller 101, and the third sensor 303 is positioned on the other side (-X direction side) of the second sensor 302. The first sensor 301 and the third sensor 303 are positioned on the first virtual line 401 or upstream of the first virtual line 401 in the transport direction F. Furthermore, the first sensor 301 and the second sensor 302 are positioned on or upstream of the second virtual line 402 in the transport direction F, relative to the second virtual line 402, which connects the other end P2e (-X direction side) of position P2, the nip position of the second feed roller 102, and the one end P71e (+X direction side) of position P7, the nip position of the first transport roller pair 7. With this configuration, the image reading device 1 of this embodiment can detect skew before the medium 2 is nipped by the first transport roller pair 7.
[0059] In this embodiment, as described above, the image reading device 1 has the second feed roller 102 positioned on the other side (-X direction side) of the first feed roller 101. The third sensor 303 is positioned on the other side (-X direction side) of the second sensor 302. As shown in Figure 8, with respect to the third virtual line 403 connecting the end P1e on one side (+X direction side) of position P1, which is the nip position of the first feed roller 101, and the position P11 of the first sensor 301, the position P13 of the third sensor 303 is positioned on the third virtual line 403 or upstream of the third virtual line 403 in the transport direction F. Furthermore, with respect to the fourth virtual line 404 connecting the other end P2e (-X direction side) of position P2, which is the nip position of the second feed roller 102, and the position P11 of the first sensor 301, the position P12 of the second sensor 302 is positioned on the fourth virtual line 404 or upstream of the fourth virtual line 404 in the transport direction F. With this configuration, the image reading device 1 of this embodiment can detect skew before the medium 2 is nipped by the first transport roller pair 7. Note that in the image reading device 1 of this embodiment, the third virtual line 403 and the fourth virtual line 404 are configured not to be in contact with the first transport roller pair 7.
[0060] Furthermore, in the image reading device 1 of this embodiment, as shown in Figure 9, the position P11 of the first sensor 301 is positioned downstream in the transport direction F from the fifth virtual line 405, which represents the maximum oblique angle (for example, 30° with respect to the X axis) extending from the end P1e on one side (+X direction side) of position P1, which is the nip position of the first feed roller 101. Similarly, the position P11 of the first sensor 301 is positioned downstream in the transport direction F from the sixth virtual line 406, which represents the angle that allows for the maximum oblique angle extending from the end P2e on the other side (-X direction side) of position P2, which is the nip position of the second feed roller 102. With this configuration, skew can be detected before the medium 2 is nipped by the first transport roller pair 7. In addition, skew can be corrected while the medium 2 is firmly nipped over the entire width direction (X axis direction) by the first feed roller 101 and the second feed roller 102. The maximum angle of obliqueness corresponds to the angle at which, if the obliqueness exceeds this angle, there is a risk of the medium 2 jamming or other problems occurring.
[0061] In this embodiment, the image reading device 1 calculates the amount of skew from the time difference in which the medium 2 passes through the first sensor 301 and the second sensor 302 or the first sensor 301 and the third sensor 303, and can adjust the rotational speed of the first feed roller 101 and the second feed roller 102 according to the calculated amount of skew. Furthermore, the control unit 22 can calculate the amount of skew from the difference in the amount of drive between the first feed roller 101 and the second feed roller 102, and can adjust the rotational speed of the first feed roller 101 and the second feed roller 102 according to the calculated amount of skew. For this reason, the image reading device 1 in this embodiment can suitably correct skew. In this embodiment, the image reading device 1 is equipped with an encoder (not shown) capable of measuring the amount of rotation of the motors M (first drive source M1, second drive source M2), which are the drive units for the first feed roller 101 and the second feed roller 102, respectively. The control unit 22 can then calculate the difference in drive amount between the first feed roller 101 and the second feed roller 102 from the measurement results obtained by the encoder.
[0062] Furthermore, the image reading device 1 of this embodiment can be described as comprising a media transport device having the above-described configuration and a reading unit 5 that reads the image of the media 2. Therefore, the image reading device 1 of this embodiment can read the image of the media 2 with high accuracy after skew correction.
[0063] Here, the reading unit 5 is positioned downstream of the detection unit 300 in the transport direction F. The control unit 22 can also calculate the skew amount from the image data read by the reading unit 5 and adjust the rotation speed of the first feed roller 101 and the second feed roller 102 according to the calculated skew amount. Therefore, the image reading device 1 in this embodiment can read images of the medium 2 that have been skew-corrected with particularly high accuracy through feedback control.
[0064] [Example 2] Next, the image reading device 1 of Example 2 will be described with reference to Figure 10. In Figure 10, components common to Example 1 are indicated by the same reference numerals, and detailed explanations will be omitted. Here, the image reading device 1 of this example has the same configuration as the image reading device 1 of Example 1, except for the configuration of the separation unit 11. Therefore, with respect to parts other than those described below, the image reading device 1 of this example has the same characteristics as the image reading device 1 of Example 1.
[0065] As described above, in the separation unit 11 of the image reading device 1 of Embodiment 1, the first torque limiter 211, the second torque limiter 212, the differential gear 220, the first separation roller 201, and the second separation roller 202 were configured to rotate around the same rotation axis 231. On the other hand, in the separation unit 11 of the image reading device 1 of this embodiment, as shown in Figure 10, the differential gear 220 is configured to rotate around the rotation axis 231 on which the first torque limiter 211 is provided, but the first separation roller 201 and the second separation roller 202 are configured to rotate around a rotation axis 226 different from the rotation axis 231.
[0066] In detail, a gear 222a is fixed to the conical gear 222 of the differential gear 220, and a gear 224a is fixed to the conical gear 224 of the differential gear 220. A gear 225a that meshes with gear 222a and is fixed to the first separation roller 201 is rotatable around the rotation axis 226, and a gear 225b that meshes with gear 224a and is fixed to the second separation roller 202 is rotatable around the rotation axis 226. The first separation roller 201 and the second separation roller 202 are connected by a second torque limiter 212 provided on the rotation axis 226. A separation unit 11 with this configuration has the same characteristics as the separation unit 11 of the image reading device 1 of Embodiment 1.
[0067] [Example 3] Next, the image reading device 1 of Example 3 will be described with reference to Figure 11. In Figure 11, components common to Examples 1 and 2 are indicated by the same reference numerals, and detailed explanations will be omitted. Here, the image reading device 1 of this example has the same configuration as the image reading device 1 of Examples 1 and 2, except for the configuration of the separation unit 11. Therefore, with respect to parts other than those described below, the image reading device 1 of this example has the same characteristics as the image reading device 1 of Examples 1 and 2.
[0068] As described above, in the separation unit 11 of the image reading device 1 of Embodiment 1, the first torque limiter 211, the second torque limiter 212, the differential gear 220, the first separation roller 201, and the second separation roller 202 were configured to rotate around the same rotation axis 231. On the other hand, in the separation unit 11 of the image reading device 1 of this embodiment, as shown in Figure 11, all components except the second torque limiter 212 are configured to rotate around the rotation axis 231 on which the first torque limiter 211 is provided, but the second torque limiter 212 is provided on a rotation axis 229 separate from the rotation axis 231.
[0069] In detail, the first separation roller 201 and the second separation roller 202 are not directly connected by the second torque limiter 212. Instead, a gear 227a fixed to the first separation roller 201 and rotatable on the rotation shaft 231 meshes with a gear 228a provided on the rotation shaft 229, and a gear 227b fixed to the second separation roller 202 and rotatable on the rotation shaft 231 meshes with a gear 228b provided on the rotation shaft 229. With this configuration, the first separation roller 201 and the second separation roller 202 are indirectly connected by the second torque limiter 212. This separation unit 11 also has the same characteristics as the separation unit 11 of the image reading device 1 in Embodiments 1 and 2.
[0070] [Example 4] Next, the image reading device 1 of Example 4 will be described with reference to Figure 12. In Figure 12, components common to Examples 1 to 3 are indicated by the same reference numerals, and detailed explanations will be omitted. Here, the image reading device 1 of this example has the same configuration as the image reading device 1 of Examples 1 to 3, except for the configuration of the separation unit 11. Therefore, with respect to parts other than those described below, the image reading device 1 of this example has the same characteristics as the image reading device 1 of Examples 1 to 3.
[0071] As described above, the separation unit 11 of the image reading device 1 in Examples 1 to 3 was equipped with a differential gear 220. On the other hand, the separation unit 11 of the image reading device 1 in this embodiment is equipped with a gear unit 240 in addition to the differential gear 220, as shown in Figure 12. The rotation shaft 241 of the gear unit 240 is equipped with a second torque limiter 212, a third torque limiter 213, a fourth torque limiter 214, a first separation roller 201, and a second separation roller 202. The third torque limiter 213 is connected to the first separation roller 201, and the fourth torque limiter 214 is connected to the second separation roller 202. If the limit torque value of the first torque limiter 211 in the separation unit 11 of the image reading device 1 in Examples 1 to 3 is T, then the limit torque values of the third torque limiter 213 and the fourth torque limiter 214 are 1 / 2T, respectively. In other words, in this embodiment, a torque limiter having a limit torque value obtained by equally dividing the limit torque value of the first torque limiter 211 is connected to each of the first separation roller 201 and the second separation roller 202. The third torque limiter 213 and the fourth torque limiter 214 also perform the role of the first torque limiter 211. The separation unit 11 with this configuration has the same characteristics as the separation unit 11 of the image reading device 1 in Embodiments 1 to 3, except for the unique feature of having a differential gear 220.
[0072] The present invention is not limited to the embodiments described above, and can be realized in various configurations without departing from its spirit. Furthermore, the technical features in the embodiments corresponding to the technical features in each embodiment described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. In addition, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]
[0073] 1…Image reading device (media transport device), 2…Media, 3…Transport path, 5…Reading unit, 6…Transport unit, 7…First transport roller pair, 8…Second transport roller pair, 9…Third transport roller pair, 10…Feeding unit, 11…Separation unit, 12…Pick roller, 13…Straight path, 14…U-turn path, 15…Fourth transport roller pair, 16…Fifth transport roller pair, 17…Discharge roller pair, 18…Discharge direction, 19…Discharge tray, 21…Feeding tray, 22…Control unit, 30…Media discharge device ,31...Discharge section, 32...Mounting surface, 33...Telescopic change section, 34...Base end, 35...Pivot point, 37...Tip, 38...Base tray, 39...Auxiliary tray, 44...Other end, 51...First reading section, 52...Second reading section, 101...First feeding roller, 102...Second feeding roller, 111...Gear train, 112...Gear train, 201...First separation roller, 202...Second separation roller, 211...First torque limiter, 212...Second torque limiter, 213...Third torque limiter, 2 14...4th torque limiter, 220...Differential gear, 221...Case, 222...Conical gear, 223...Pinion gear, 224...Conical gear, 225a...Gear, 225b...Gear, 226...Rotating shaft, 227a...Gear, 227b...Gear, 228a...Gear, 228b...Gear, 229...Rotating shaft, 231...Rotating shaft, 232...Gear, 233...Gear, 234...Rotating shaft, 240...Gear unit, 241...Rotating shaft, 300...Detection unit, 301...1st sensor, 302 ...Second sensor, 303...Third sensor, 401...First virtual line, 402...Second virtual line, 403...Third virtual line, 404...Fourth virtual line, 405...Fifth virtual line, 406...Sixth virtual line, F...Conveying direction, L1...Interval, L2...Range, L3...Distance, L4...Minimum width, M...Motor, M1...First drive source, M2...Second drive source, P1...Position, P1e...End, P2...Position, P2e...End, P7...Position, P11...Position, P12...Position, P13...Position, P71e...End, P72e...End
Claims
1. A feeding unit for feeding the medium downstream in the medium transport direction, comprising: a first feeding roller and a second feeding roller that rotates together with the first feeding roller, which are spaced apart in a width direction intersecting the transport direction; A separation unit for separating the medium that is fed together with the feeding unit, comprising a first separation roller positioned opposite the first feeding roller, and a second separation roller positioned opposite the second feeding roller, A detection unit for detecting the skew of the medium supplied from the supply unit, A control unit that adjusts the rotational speed of the first feed roller and the second feed roller based on the skew state of the medium detected by the detection unit, Equipped with, The detection unit is configured such that the first sensor, the second sensor, and the third sensor are arranged at intervals in the width direction. The first sensor is positioned downstream in the conveying direction from the nip position between the first feed roller and the first separation roller and the nip position between the second feed roller and the second separation roller, and is positioned between the first feed roller and the second feed roller in the width direction, and is positioned to overlap with the first feed roller and the second feed roller in the width direction. The second sensor is positioned to one side of the first sensor in the width direction. The media transport device is characterized in that the third sensor is positioned on the other side of the first sensor in the width direction.
2. In the media transport device described in claim 1, The separation unit is equipped with a first torque limiter, The first separation roller is capable of rotating together with the first feeding roller when a torque greater than a first torque value derived from the limit torque value of the first torque limiter is applied. The second separation roller is capable of both rotating together with the first separation roller and rotating independently of the first separation roller. The media conveying device is characterized in that the first torque value is the torque value applied to the first separation roller when the limit torque value is applied to the first torque limiter.
3. In the media transport device described in claim 1, A media transport device characterized in that the second sensor and the third sensor are positioned downstream of the first sensor in the transport direction.
4. In the media transport device described in claim 1, A media transport device characterized in that the distance between the second sensor and the third sensor in the width direction is narrower than the minimum width of the usable media.
5. In the media transport device described in claim 1, The system includes a pair of conveying rollers positioned downstream of the feeding section in the conveying direction, The second feeding roller is positioned on the other side of the first feeding roller. The third sensor is positioned on the other side of the second sensor. With respect to a first virtual line connecting one end of the nip position of the first feeding roller and the other end of the nip position of the transport roller pair, the first sensor and the third sensor are positioned on the first virtual line or upstream of the first virtual line in the transport direction. A media conveying device characterized in that the first sensor and the second sensor are positioned on or upstream of the second virtual line in the conveying direction relative to the second virtual line connecting the other end of the nip position of the second feeding roller and the one end of the nip position of the conveying roller pair.
6. In the media transport device described in claim 1, The second feeding roller is positioned on the other side of the first feeding roller. The third sensor is positioned on the other side of the second sensor. With respect to a third virtual line connecting the one end of the nip position of the first feed roller and the first sensor, the third sensor is positioned on the third virtual line or upstream of the third virtual line in the conveying direction. A media conveying device characterized in that the second sensor is positioned on or upstream of the fourth virtual line in the conveying direction relative to the fourth virtual line connecting the other end of the nip position of the second feeding roller and the first sensor.
7. In the media transport device described in claim 1, The media conveying device is characterized in that the control unit calculates a skew amount from the time difference in which the medium passes through the first sensor and the second sensor or the first sensor and the third sensor or from the difference in the amount of drive between the first feed roller and the second feed roller, and adjusts the rotational speed of the first feed roller and the second feed roller respectively according to the calculated skew amount.
8. A media transport device according to any one of claims 1 to 7, An image reading device comprising a reading unit for reading an image of the aforementioned medium.
9. In the image reading device described in claim 8, The reading unit is positioned downstream of the detection unit in the transport direction. The image reading device is characterized in that the control unit calculates a skew amount from the image data read by the reading unit and adjusts the rotational speed of the first feed roller and the second feed roller according to the calculated skew amount.