Media feeding device and image reading device

Abstract

To provide a medium feeding device capable of performing medium separation further appropriately or an image reading device with the medium feeding device.SOLUTION: A medium feeding device 10 comprises: a feeding roller 14; a separation roller 15 which is a roller that separates a sheet P by nipping the sheet P between the feeding roller 14 and itself, to which a drive torque by a drive source is applied in a second rotation direction B opposite to a first rotation direction A for feeding the sheet P downstream; and a torque limiter 41 for causing the separation roller 15 to idle in the first rotation direction A when the rotational torque applied to the separation roller 15 in the first rotational direction A exceeds the limit torque which is a predetermined torque upper limit value. The medium feeding device is configured to be able to change a separation setting including the pressing load of the separation roller 15, the rotational speed of the separation roller 15, and the limit torque in accordance with the conditions at the time of feeding.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a medium feeding device for feeding a document and an image reading device for reading a document fed by the medium feeding device.

Background Art

[0002] Some scanners, which are an example of an image reading device, are provided with a medium feeding device (also called an ADF (Auto Document Feeder)) that automatically feeds a medium as a document, and may be configured to be able to automatically feed and read a plurality of media. As the medium feeding device, there is a configuration including a medium tray on which a plurality of media are placed, a feeding roller that rotates in contact with the surface of the medium set on the medium tray to feed out the medium, and a separation roller that contacts the feeding roller to separate the medium.

[0003] By the way, there are various types of media. For example, when a separation force by the separation roller is applied to thin paper or old paper with low rigidity of the medium, there is a risk of causing significant damage to the medium. For this reason, a medium feeding device has been proposed that is configured to be able to select a separation mode in which separation is performed by the separation roller and a non-separation mode in which the medium is fed without performing separation by the separation roller according to the type of the medium (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In conventional media feeding devices, while it is possible to choose whether or not to perform separation by the separation roller by selecting between the separation mode and the non-separation mode, the separation resistance of the media in the separation mode was uniformly set. Therefore, even when the separation mode was selected, depending on the type of media, proper separation may not have been possible.

[0006] This invention has been made in view of the above circumstances, and its purpose is to provide a media feeding device that can more appropriately separate media, or an image reading device equipped with the media feeding device. [Means for solving the problem]

[0007] To solve the above problems, a media feeding device according to a first aspect of the present invention comprises: a media mounting section on which media is placed; a feeding roller for feeding the media from the media mounting section; a separation roller for separating the media by nipping it between itself and the feeding roller, wherein a driving torque from a drive source is applied to the separation roller in a second rotational direction opposite to a first rotational direction for sending the media downstream; and a torque limiter that causes the separation roller to spin freely in the first rotational direction when the rotational torque applied to the separation roller in the first rotational direction exceeds a predetermined torque upper limit value, wherein the device also comprises a load changing means for changing the pressing load of the separation roller against the feeding roller; a speed changing means for changing the rotational speed of the drive source; and a torque changing means for changing the limit torque, and is configured to allow the separation settings to be changed according to the conditions during feeding, including the pressing load, the rotational speed, and the limit torque.

[0008] According to this embodiment, the separation settings, which include the pressing load, the rotational speed, and the limit torque, can be changed according to the conditions during feeding, thereby enabling more appropriate separation of the medium. Furthermore, "conditions for supply and delivery" refers to at least one or a combination of all conditions that affect separability, such as the type of media and the number of sheets.

[0009] A second aspect of the present invention is characterized in that, in the first aspect, the load changing means comprises a first pressing portion and a second pressing portion having a different pressing force from the first pressing portion, and the pressing load of the separating roller toward the feeding roller is changed by switching the pressing portion that presses the separating roller toward the feeding roller between the first pressing portion and the second pressing portion.

[0010] According to this embodiment, the load changing means comprises a first pressing portion and a second pressing portion having a different pressing force from the first pressing portion, and the pressing force of the separating roller toward the feeding roller can be changed by switching between the first pressing portion and the second pressing portion to change the pressing load of the separating roller toward the feeding roller.

[0011] A third aspect of the present invention is characterized in that, in the first aspect, the load changing means comprises a pressing spring disposed between a spring support and the separation roller, which presses the separation roller toward the feeding roller, and the spring length of the pressing spring is changed by moving the spring support, thereby changing the pressing load of the separation roller toward the feeding roller.

[0012] According to this embodiment, the load changing means is configured such that a pressing spring is disposed between the spring support and the separation roller to press the separation roller toward the feeding roller, and the spring length of the pressing spring is changed by moving the spring support to change the pressing force of the separation roller toward the feeding roller, thereby changing the pressing load of the separation roller toward the feeding roller.

[0013] A fourth aspect of the present invention is characterized in that, in the first aspect, the separation roller is rotatably held and has a pivot shaft that pivots the held separation roller so as to move it toward and away from the feed roller, and a pressing part presses the separation roller toward the feed roller via the roller holding part, wherein the load changing means is configured to change the pressing load of the separation roller toward the feed roller by moving the position of the pivot shaft.

[0014] According to this embodiment, the pressing load of the separating roller against the feeding roller can be changed by the load changing means configured to change the pressing load of the separating roller against the feeding roller by moving the position of the pivot axis of the roller holding portion.

[0015] A fifth aspect of the present invention, in the first aspect, comprises a roller holding portion having a pivot axis that rotatably holds the separation roller and pivots the held separation roller toward and toward the feeding roller, and a pressing portion that presses the separation roller toward the feeding roller via the roller holding portion, wherein the load changing means restricts the position of the separation roller relative to the feeding roller against the pressing force of the pressing portion by contacting the roller holding portion, and is equipped with a displacement member that is displaceable in a direction that changes the position of the separation roller relative to the feeding roller.

[0016] According to this embodiment, the pressing load of the separation roller on the feeding roller is changed by restricting the position of the separation roller relative to the feeding roller, so that the pressing load of the separation roller on the feeding roller can be easily changed.

[0017] A sixth aspect of the present invention, in the first aspect, includes a power transmission mechanism for transmitting power from a drive source that drives the separation roller, the power transmission mechanism includes a first gear integrally provided on the rotating shaft of the separation roller, a second gear integrally provided on the rotating shaft of the separation roller and having a different reduction ratio from the first gear, and a switching gear displaceable between a first position for transmitting power from the drive source to the first gear and a second position for transmitting power from the drive source to the second gear, the load changing means is configured to change the pressing load of the separation roller on the feeding roller by switching the switching gear between the first position and the second position.

[0018] According to this embodiment, the pressing load of the separating roller against the feeding roller can be changed by the load changing means configured to change the pressing load of the separating roller against the feeding roller by switching the switching gear of the power transmission mechanism between the first position and the second position.

[0019] A seventh aspect of the present invention is characterized in that, in any of the first to sixth aspects, the torque limiter comprises a first torque limiter and a second torque limiter having a different free-running torque than the first torque limiter, and the torque changing means is configured to include a switching unit that switches between a state in which the rotational torque is applied to the first torque limiter and a state in which the rotational torque is applied to the second torque limiter. According to this embodiment, the torque changing means can be easily configured.

[0020] An eighth aspect of the present invention is characterized in that, in any of the first to sixth aspects, the torque limiter comprises a first torque limiter and a second torque limiter, and the torque changing means is configured to include a switching unit that switches between a state in which the rotational torque is applied to one of the first torque limiter and the second torque limiter and a state in which the rotational torque is applied to both. According to this aspect, the torque changing means can be easily configured.

[0021] A ninth aspect of the present invention is any one of the first to sixth aspects, further comprising a power transmission mechanism between the torque limiter and the separation roller, the power transmission mechanism comprising a first power transmission path, a second power transmission path having a different reduction ratio from the first power transmission path, and switching means for switching between the first power transmission path and the second power transmission path. According to this aspect, the torque changing means can be easily configured.

[0022] A tenth aspect of the present invention is any one of the first to ninth aspects, further comprising a control unit as the speed changing means for controlling the drive source. According to this aspect, the rotation speed of the separation roller can be controlled by the control unit.

[0023] An eleventh aspect of the present invention is the tenth aspect, wherein the control unit controls at least one of the load changing means and the torque changing means. According to this aspect, at least one of the load changing means and the torque changing means can be controlled. <000~093>

[0024] A twelfth aspect of the present invention is the tenth or eleventh aspect, wherein the separation roller is switchable between a separation state for separating the medium and a non-separation state for not separating the medium, and the control unit can select a separation mode in which the separation roller is in the separation state for feeding or a non-separation mode in which the separation roller is in the non-separation state for feeding, based on the type of the medium to be fed.

[0025] According to this aspect, the control unit can select whether to feed in the separation mode or the non-separation mode according to the type of the medium, and can feed various media more appropriately. <00001~00> A thirteenth aspect of the present invention is characterized in that, in the twelfth aspect, the drive source can rotate the separation roller in the first rotational direction, and the control unit rotates the separation roller in the first rotational direction by a predetermined amount before executing the separation mode.

[0027] According to this embodiment, the control unit rotates the separation roller by a predetermined amount in the first rotational direction before executing the separation mode, thereby ensuring that the medium is nipped between the separation roller and the feeding roller, and reducing the risk of non-feeding of the medium.

[0028] A fourteenth aspect of the present invention is characterized in that, in any of the first to thirteenth aspects, when separating a second medium which is relatively thinner than the first medium, at least one of the pressing load, the rotational speed, and the limiting torque is suppressed compared to when separating the first medium.

[0029] According to this embodiment, when separating a second medium which is relatively thinner than the first medium, the separation resistance by the separation roller can be reduced by suppressing at least one of the pressing load, rotational speed, and limiting torque compared to when separating the first medium, thereby reducing the risk of damaging the second medium due to separation by the separation roller.

[0030] A fifteenth aspect of the present invention is characterized in that, in any of the first to thirteenth aspects, when separating a second medium having a relatively higher frictional force than the first medium, at least one of the pressing load, the rotational speed, and the limiting torque is increased compared to when separating the first medium.

[0031] According to this embodiment, when separating the second medium, which has a relatively higher frictional force than the first medium, at least one of the pressing load, rotational speed, and limiting torque is increased compared to when separating the first medium. This increases the separation resistance by the separation roller, making it possible to more reliably separate the second medium, which has a higher frictional force, i.e., the medium that is difficult to separate.

[0032] A sixteenth aspect of the present invention is characterized in that, in any of the first to thirteenth aspects, when separating a second medium which is relatively thicker than the first medium, the pressing load is increased compared to when separating the first medium.

[0033] If the medium being fed is a second medium that is relatively thicker than the first medium, it may not be fed by the feed roller, resulting in a non-feed state. According to this embodiment, when separating a second medium which is relatively thicker than the first medium, the pressing load is increased compared to when separating the first medium, thereby ensuring a firm nip between the separation roller and the feeding roller, and thereby improving the feeding performance by the feeding roller. This reduces the risk of cardboard not being fed.

[0034] An image reading device according to the 17th aspect of the present invention is characterized by comprising: a reading unit for reading a medium; and a medium feeding device according to any one of claims 1 to 15 for feeding the medium toward the reading unit.

[0035] According to this embodiment, in an image reading device equipped with a medium feeding device for feeding a medium toward the reading unit, the same effects and advantages as any one of the first to sixteenth embodiments can be obtained. [Brief explanation of the drawing]

[0036] [Figure 1] An external perspective view showing the scanner according to the present invention. [Figure 2]A perspective view of the scanner according to the present invention, taken from a different angle than that shown in Figure 1. [Figure 3] A side cross-sectional view showing the paper transport path in the scanner according to the present invention. [Figure 4] A block diagram showing the configuration of the scanner according to the present invention. [Figure 5] A schematic diagram showing part of the power transmission mechanism that transmits power from the first drive source to the separation roller. [Figure 6] A diagram illustrating the operation of the separation roller. [Figure 7] A perspective view illustrating the torque changing mechanism. [Figure 8] A flowchart showing an example of the separation mode. [Figure 9] A schematic side view illustrating the load changing mechanism. [Figure 10] A perspective view illustrating an example of a change in the torque changing mechanism (Example 1). [Figure 11] An enlarged view of the main parts illustrating Example 1 of the torque changing mechanism modification. [Figure 12] A perspective view illustrating example 2 of the torque changing mechanism modification. [Figure 13] A cross-sectional view illustrating example 2 of the torque changing mechanism modification. [Figure 14] A schematic diagram illustrating example 1 of the load changing mechanism modification. [Figure 15] A side view illustrating example 2 of the load changing mechanism modification. [Figure 16] A schematic diagram illustrating example 3 of the load changing mechanism modification. [Figure 17] A perspective view illustrating example 4 of the load changing mechanism modification. [Modes for carrying out the invention]

[0037] [First Embodiment] First, an overview of an image reading device equipped with a media feeding device according to one embodiment of the present invention will be described. In this embodiment, as an example of an image reading device, a document scanner (hereinafter simply referred to as scanner 1) capable of reading at least one side of the front and back surfaces of a sheet of paper as the "medium" is given.

[0038] Figure 1 is an external perspective view showing the scanner according to the present invention. Figure 2 is a perspective view of the scanner according to the present invention from a different angle than that in Figure 1. Figure 3 is a side cross-sectional view showing the paper transport path in the scanner according to the present invention. Figure 4 is a block diagram showing the configuration of the scanner according to the present invention. Figure 5 is a schematic diagram showing a part of the power transmission mechanism that transmits power from the first drive source to the separation roller. Figure 6 is a diagram illustrating the operation of the separation roller. Figure 7 is a perspective view of the torque changing means. Figure 8 is a flowchart showing an example of a separation mode. Figure 9 is a schematic side view illustrating the load changing means.

[0039] Figure 10 is a perspective view illustrating example 1 of the torque changing mechanism modification. Figure 11 is an enlarged view of the main part illustrating example 1 of the torque changing mechanism modification. Figure 12 is a perspective view illustrating example 2 of the torque changing mechanism modification. Figure 13 is a cross-sectional view illustrating example 2 of the torque changing mechanism modification. Figure 14 is a schematic diagram illustrating example 1 of the load changing mechanism modification. Figure 15 is a side view illustrating example 2 of the load changing mechanism modification. Figure 16 is a schematic diagram illustrating example 3 of the load changing mechanism modification. Figure 17 is a perspective view illustrating example 4 of the load changing mechanism modification.

[0040] In each diagram, the XYZ coordinate system is such that the X direction is the device width direction and the paper width direction, and the Y direction is the paper transport direction. The Z direction is the direction that intersects the Y direction and generally represents the direction perpendicular to the surface of the paper being transported. The +Y direction side is the front side of the device, and the -Y direction side is the rear side of the device. When viewed from the front side of the device, the left side is the +X direction and the right side is the -X direction. The +Z direction is the upper side of the device (including the top and top surface, etc.), and the -Z direction side is the lower side of the device (including the bottom and bottom surface, etc.). The direction in which the paper is fed (+Y direction side) is called "downstream," and the opposite direction (-Y direction side) is called "upstream."

[0041] ■■■Scanner Overview■■■ The scanner 1 according to the present invention will be described below, primarily with reference to Figures 1 and 2. The scanner 1 shown in Figures 1 and 2 includes a reading unit 20 (Figure 3) inside the main body 2 that reads an image from a sheet of paper P (medium). The main body of the device 2 is composed of a lower unit 3 and an upper unit 4. The upper unit 4 is attached to the lower unit 3 so as to be able to open and close with the downstream side in the paper transport direction as the pivot point. The upper unit 4 can be rotated to the front of the device to open, exposing the paper transport path of the paper P, which allows for easy maintenance such as removing paper jams and cleaning of the paper P.

[0042] A media mounting section 11 for placing paper P is provided on the rear side (-Y axis side) of the main body of the device 2. Reference numeral 11a denotes the mounting surface 11a of paper P. Inside the main body 2 of the device, there is a media feeding device 10 (Figure 3) that feeds paper P from the media placement section 11 toward the reading section 20. Furthermore, in scanner 1, the media placement section 11 is detachably attached to the main body 2 of the device. The configuration of the media feeding device 10 will be described later.

[0043] Furthermore, the media placement section 11 is provided with a pair of left and right edge guides 12, 12, each having a guide surface 13 that guides the side edges of the paper P in the width direction (X direction) intersecting the feeding direction (Y direction). The edge guides 12, 12 are provided so as to be slidable in the X-axis direction according to the size of the paper P. In this embodiment, the edge guides 12, 12 are configured such that, by a known rack and pinion mechanism, the other edge guide 12 (-X side) moves in the opposite direction in accordance with the X movement of one edge guide 12 (e.g., the +X side). In other words, in the media placement section 11, the paper P is aligned to the center in the width direction, and the feed roller 14, which will be described later, is provided in the central region in the width direction, so that paper is fed in a so-called center-feed system. Figure 1 shows the state in which the edge guides 12, 12 are in their outermost position, and Figure 2 shows the state in which the edge guides 12, 12 are in their innermost position.

[0044] As shown in Figure 1, the media mounting section 11 includes a first auxiliary paper support 8 and a second auxiliary paper support 9. As shown in Figure 2, the first auxiliary paper support 8 and the second auxiliary paper support 9 can be housed inside the media mounting section 11 and are configured to be pull-out from the media mounting section 11 as shown in Figure 1, and the length of the mounting surface 11a can be adjusted.

[0045] The main unit 2 of the device is equipped with an operation panel 7 on the front side of the upper unit 4, which serves as both an operation unit for operating various reading settings and executing readings, and a display unit for displaying reading settings and other information. The upper unit 4 is provided with a feed port 6 that connects to the inside of the main body 2 of the device, and the paper P placed on the media placement section 11 is fed from the feed port 6 towards the reading section 20 (Figure 3) located inside the main body 2 of the device. Furthermore, a paper output tray 5, which will be described later, is provided on the front side of the lower unit 3.

[0046] ■■■Regarding the paper transport path in scanners■■■ Next, the paper transport path in scanner 1 will be explained, primarily with reference to Figure 3. Note that the dotted line in Figure 3 indicates the transport path of paper P. In scanner 1, the original document, paper P, is fed towards the reading unit 20 by the media feeder 10.

[0047] In this embodiment, the media feeding device 10 shown in Figure 3 includes the aforementioned media placement section 11, a feeding roller 14 that feeds the paper P from the media placement section 11 toward the reading section 20, and a separation roller 15 that nips the paper P between itself and the feeding roller 14 to separate the paper P. In Figure 3, the separation roller 15 is configured to receive driving torque from the first drive source 25 (Figure 4), which will be described later, in the second rotation direction B, which is opposite to the first rotation direction A that feeds the paper P downstream (+Y direction).

[0048] Furthermore, a torque limiter (for example, the torque limiter 41 shown in Figure 7) is provided to cause the separation roller 15 to spin freely in the first rotation direction A (Figure 3) if the rotational torque applied to the separation roller 15 in the first rotation direction A exceeds a predetermined torque upper limit value, which is the limit torque. The rotational torque applied to the separation roller 15 in the first rotational direction A (Figure 3) is applied by the feed roller 14 if there is no paper P between the separation roller 15 and the feed roller 14, and by the paper P if there is paper P between the separation roller 15 and the feed roller 14. If the rotational torque applied to the separation roller 15 in the first rotational direction A (Figure 3) exceeds the limit torque, the separation roller 15 will rotate in the first rotational direction A (Figure 3) due to the rotational torque received from the feed roller 14 or the paper P. In this specification, this is defined as the free-spinning of the separation roller 15. This free-spinning of the separation roller 15 occurs when there is no paper P between the separation roller 15 and the feed roller 14, and when there is paper P between the separation roller 15 and the feed roller 14 but no double feeding occurs.

[0049] Then, if, for example, multiple sheets of paper P are interposed between the separation roller 15 and the feed roller 14, i.e., if double feeding occurs, the rotational torque applied to the separation roller 15 in the first rotational direction A (Figure 3) falls below the limit torque, so the separation roller 15 rotates in the second rotational direction B (Figure 3) by the driving torque received from the first drive source 25 (Figure 4). As a result, the sheets of paper P that were about to be double-fed are returned to the upstream side. As described above, the term "limit torque" in this specification does not refer to the free-spinning torque of the torque limiter itself, but rather to the torque that marks the boundary between whether or not the separation roller 15 will free-spin. The lower the limit torque, the easier it is for the separation roller 15 to rotate in the first rotation direction A (Figure 3). Conversely, if the limit torque is high, the force required to rotate the separation roller 15 in the first rotation direction A (Figure 3) increases. The torque changing means described later is a means for changing this limit torque.

[0050] Furthermore, the media feeding device 10 includes a load changing means (for example, load changing means 60 in Figure 4) that changes the pressing load of the separation roller 15 on the feeding roller 14, a control unit 19 that acts as a speed changing means to change the rotational speed of the first drive source that acts as a "drive source" for driving the separation roller 15, and a torque changing means (for example, torque changing means 40 in Figure 4) that changes the limit torque. The control unit 19 can change the rotational speed of the separation roller 15 by controlling the drive of the first drive source 25 (Figure 4), which serves as the drive source for the separation roller 15.

[0051] Furthermore, the media feeding device 10 is configured to allow the setting of separation parameters, which include the pressing load, the rotational speed, and the limit torque, to be changed according to the conditions during paper feeding by the feeding roller 14. Specific examples of changes to the separation settings, the configuration of the load changing means 60, and the configuration of the torque limiter 41 and torque changing means 40 will be described later.

[0052] The feeding rollers 14 are provided in pairs in the central region of the width direction (X-axis direction) intersecting the medium feeding direction (+Y direction). Separation rollers 15 are provided opposite the feeding rollers 14. As shown in Figure 5, the separation rollers 15 are also provided in pairs corresponding to the feeding rollers 14.

[0053] The paper P placed on the media placement section 11 is picked up by a feed roller 14 rotatably mounted on the lower unit 3 and fed downstream (towards the +Y direction). Specifically, the feed roller 14 rotates while in contact with the surface of the paper P facing the media placement section 11, thereby feeding the paper P downstream. Therefore, when multiple sheets of paper P are set on the media placement section 11 in the scanner 1, they are fed downstream in order from the paper P on the placement surface 11a side.

[0054] Downstream of the feeding roller 14, there is a pair of transport rollers 16, a reading unit 20, and a pair of discharge rollers 17. The transport roller pair 16 is located upstream of the reading unit 20 and transports the paper P fed by the feed roller 14 toward the reading unit 20. The transport roller pair 16 is composed of a transport drive roller 16a and a transport driven roller 16b.

[0055] A double-feed detection unit 28 for detecting double feeding of paper P is provided downstream of the feed roller 14 and upstream of the transport roller pair 16. As the double-feed detection unit 28, for example, an ultrasonic sensor can be used, which comprises a transmitter that emits ultrasonic waves and a receiver that is provided opposite the transmitter with the transported paper in between.

[0056] The reading unit 20 includes an upper reading sensor 20a provided on the upper unit 4 side and a lower reading sensor 20b provided on the lower unit 3 side. In this embodiment, the upper reading sensor 20a and the lower reading sensor 20b are configured as a contact-in-sensor (CISM) module, for example.

[0057] After the reading unit 20 reads the image of at least one side of the front and back of the paper P, it is nipped by a pair of discharge rollers 17 located downstream of the reading unit 20 and discharged from a discharge port 18 provided on the front side of the lower unit 3. The pair of discharge rollers 17 is composed of a discharge drive roller 17a and a discharge driven roller 17b.

[0058] In this embodiment, the feeding roller 14, the separating roller 15, the transport drive roller 16a, and the discharge drive roller 17a are rotationally driven by at least one drive source provided within the lower unit 3. As mentioned above, the separation roller 15 is rotationally driven by the first drive source 25 (Figure 4). In this embodiment, the transport drive roller 16a and the discharge drive roller 17a are also driven by the same first drive source 25 as the separation roller 15. The feeding roller 14 is driven by a second drive source 26, which is separate from the first drive source 25.

[0059] As shown in Figure 4, the operation of the first drive source 25 and the second drive source 26 is controlled by the control unit 19, thereby controlling the driving of the feed roller 14, the separation roller 15, the transport drive roller 16a, and the discharge drive roller 17a. In other words, the paper feeding operation of the paper P is controlled by the control unit 19.

[0060] The lower unit 3 is provided with a paper output tray 5 that can be pulled out from the output port 18 toward the front of the device. The paper output tray 5 can be stored in the bottom of the lower unit 3 (Figure 1) or pulled out toward the front of the device (not shown). When the paper output tray 5 is pulled out, the paper P discharged from the output port 18 can be stacked on the paper output tray 5.

[0061] As shown in Figure 3, a first detection unit 21 is provided upstream of the feed roller 14 in the media feeding direction, within the paper placement area of ​​the media placement unit 11, to detect the presence or absence of paper P placed on the media placement unit 11. Furthermore, a second detection unit 22, a third detection unit 23, and a fourth detection unit 24 are provided downstream of the feed roller 14, downstream of the transport roller pair 16, and downstream of the discharge roller pair 17, respectively. The second detection unit 22, the third detection unit 23, and the fourth detection unit 24 can detect the position of paper P in the media feeding direction. It is also possible to configure the system to detect the skew (diagonal movement) of the fed paper P using any of the second detection unit 22, the third detection unit 23, and the fourth detection unit 24. In this embodiment, the first detection unit 21, the second detection unit 22, and the third detection unit 23 and fourth detection unit 24 are provided in the central region in the width direction.

[0062] Furthermore, in this embodiment, the first detection unit 21, the second detection unit 22, the third detection unit 23, and the fourth detection unit 24 are optical sensors that include a light-emitting unit (not shown) that emits light and a light-receiving unit (not shown) that receives reflected light from the light-emitting unit. In addition to the optical sensors, the first to fourth detection units 21 to 24 may also use ultrasonic sensors comprising a transmitter that emits ultrasonic waves and a receiver positioned opposite the transmitter with the paper being transported in between. Furthermore, lever-type sensors that detect the displacement of a mechanical lever moved by contact with the transported paper using optical or electrical contact methods may also be used.

[0063] ■■■Regarding paper separation during feeding using a media feeding device■■■ ◆◆Separation Mode and Non-Separation Mode◆◆ First, in the media feeding device 10, the separation roller 15 is configured to be switchable between a separation state in which the paper P is separated and a non-separation state in which the paper P is not separated. When feeding paper P from the media placement unit 11, the control unit 19 can select either a separation mode in which the separation roller 15 is in the separation state for feeding, or a non-separation mode in which the separation roller 15 is in the non-separation state for feeding. The separation roller 15 is switched between the separated and unseparated states by the separation switching means 27 shown in Figure 5. The separation switching means 27 is provided in the power transmission mechanism 30 that transmits power from the first drive source 25.

[0064] Figure 5 shows the first gear train 31, which constitutes part of the power transmission mechanism 30. The first gear train 31 comprises a gear 32, a first moving gear 33 as a separation and switching means 27, a gear 34, a gear 35, a second moving gear 36, and a torque limiter 41 with teeth around it. The second moving gear 36 and the torque limiter 41 are components that constitute the torque changing means 40, which will be described later.

[0065] The gear 32 shown in Figure 5 is connected to the rotating shaft 37 of the transport drive roller 16a of the transport roller pair 16 (not shown in Figure 5), and is configured to receive power from the first drive source 25 via the transport roller pair 16 (which is driven by the power of the first drive source 25). The power received by the gear 32 of the first gear train 31 is transmitted to the separation roller 15 via multiple gears. Although the transmission mechanism from the first drive source 25 to the transport roller pair 16 of the power transmission mechanism 30 is omitted here, it can be constructed using a gear train or belt mechanism composed of multiple gears, similar to the first gear train 31.

[0066] Here, the first moving gear 33 is provided so as to be displaceable in the X-axis direction between the position shown by the solid line in Figure 5 and the position shown by the dotted line in Figure 5. At the position shown by the dotted line in Figure 5, the first moving gear 33 meshes with gears 32 and 34, and the driving force of the first drive source 25 (Figure 4) is transmitted to the separation roller 15, causing the separation roller 15 to rotate in the second rotation direction B. This state is referred to as the "separation state" in which the paper P is separated. Furthermore, at the position indicated by the dotted line in Figure 5, the first moving gear 33 is not meshed with gears 32 and 34, and the driving force of the first drive source 25 is no longer transmitted to the separation roller 15. This state is referred to as the "non-separation state," in which the paper P is not separated. In the non-separation state, the separation roller 15 can rotate freely with light force.

[0067] Furthermore, in this embodiment, the switching between the "separated state" and the "non-separated state" by the separation switching means 27 can be performed not only by manually moving the first moving gear 33 in the X-axis direction, but also by automatically moving the first moving gear 33 in the X-axis direction by the operation of an electromagnetic clutch (not shown) controlled by the control unit 19. The separation switching means 27 can also be configured to switch either manually or automatically.

[0068] When the control unit 19 controls the switching between the "separated state" and the "non-separated state" by the separation switching means 27, the control unit 19 decides, for example, whether to feed the paper in separated mode or in non-separated mode, based on the type of paper P set on the operation panel 7. The non-separation mode is selected when feeding paper that would be damaged if separated by the separation roller 15 (for example, paper with multiple layers on the surface that easily peel off, such as instant photographs) or when feeding booklets such as bankbooks or passports. By selecting whether to feed the paper in separate mode or non-separated mode depending on the type of paper P, various types of paper P can be fed appropriately. Furthermore, the user can decide whether to perform feeding in separated mode or non-separated mode, and manually switch between the "separated state" and the "non-separated state" using the separated switching means 27. In this case, it is preferable to provide a sensor or the like to detect whether the separated switching means 27 is set to separated mode or non-separated mode, so that the control unit 19 can understand which state the separated switching means 27 is currently in. Alternatively, the user can select either the isolated mode or the non-isolated mode using the control panel 7, and the control unit 19 can be configured to switch between the "isolated state" and the "non-isolated state".

[0069] Furthermore, when the media feeding device 10 is performing feeding in separation mode, it is configured to allow the separation settings to be changed according to the feeding conditions, as described above. The feeding conditions refer to at least one or a combination of all conditions that affect separation, such as the type of paper and the number of sheets placed on the media placement section 11. The separation settings for the separation mode include the pressing load of the separation roller 15 against the feed roller 14, the rotational speed of the separation roller 15, and the limit torque of the separation roller 15. The specific separation settings in separation mode will be described below. The various means for changing the separation settings (torque changing means 40 and load changing means 60) will be explained after the specific examples of separation settings have been described.

[0070] ◆◆About Separation Settings in Separation Mode◆◆ <<Separation setting W1>> The separation setting W1 is a setting that changes depending on the difference in paper thickness during paper feeding. The separation setting W1, when separating a second sheet of paper (second medium) which is relatively thinner than the first sheet of paper (first medium) in the media feeding device 10, suppresses at least one of the pressing load of the separation roller 15, the rotational speed of the separation roller 15, and the limit torque of the separation roller 15 compared to when separating the first sheet of paper.

[0071] In other words, when separating a second sheet of paper that is relatively thin (hereinafter simply referred to as "thin"), at least one of the following is done compared to separating a first sheet of paper that is relatively thicker than the second sheet (hereinafter simply referred to as "thick"): reducing the pressing load of the separation roller 15, slowing down the rotation speed of the separation roller 15, or reducing the limit torque.

[0072] The separation of paper by the separation roller 15 can usually be reliably achieved by increasing the separation resistance between the separation roller 15 and the feed roller 14 to a certain extent. Here, "separation resistance" is determined by a combination of the pressing load of the separation roller 15, the rotational speed of the separation roller 15, and the limit torque of the separation roller 15. For example, increasing the pressing load of the separation roller 15 increases the separation resistance, increasing the rotational speed of the separation roller 15 increases the separation resistance, and increasing the limit torque of the separation roller 15 increases the separation resistance. However, the thinner second paper tends to have low rigidity, and if the separation resistance is too high, the second paper may tear or wrinkle.

[0073] When separating the second (thin) sheet of paper, the separation resistance when separating the second (thin) sheet of paper can be reduced compared to when separating the first (thick) sheet of paper by suppressing at least one of the pressing load of the separation roller 15, the rotational speed of the separation roller 15, or the limit torque of the separation roller 15. This reduces the risk of damage such as tearing or wrinkling occurring to the thin second sheet of paper due to separation by the separation roller 15. Furthermore, when separating the second sheet of paper, the three factors that are suppressed compared to when separating the first sheet of paper may be all three: pressing load, rotational speed, and limit torque, or one or two of them may be selected to be suppressed.

[0074] <<Separation setting W2>> Next, the separation setting W2 is a setting that is changed depending on the difference in paper friction during feeding. Here, paper friction is synonymous with the friction between sheets of paper. The separation setting W2 increases at least one of the pressing load, rotational speed, and limit torque in the media feeding device 10 when separating a second sheet of paper (second medium) which has a relatively higher frictional force than the first sheet of paper (first medium), compared to when separating the first sheet of paper. In other words, when separating the second sheet of paper, at least one of the following is done compared to separating the first sheet of paper: increasing the pressing load of the separation roller 15, increasing the rotational speed of the separation roller 15, or increasing the limit torque.

[0075] When separating paper with high friction, if the separation resistance between the separation roller 15 and the feed roller 14 is small, separation may not be possible, and the feed roller 14 may not feed the paper, resulting in a non-feed state. Examples of paper with high friction include photographic paper with a coated layer on the printing surface. In contrast, plain paper without a coated layer has relatively low friction. Here, when separating a second sheet of paper with relatively higher friction (hereinafter referred to as high friction) from a first sheet of paper with relatively lower friction (hereinafter referred to as low friction), at least one of the pressing load, rotational speed, and limit torque is increased compared to when separating the first sheet of paper (low friction). Therefore, when separating the high-friction second sheet of paper, the separation resistance by the separation roller 15 is increased compared to when separating the low-friction first sheet of paper, thereby improving the separation performance. As a result, the separation of the high-friction second sheet of paper, i.e., the difficult-to-separate paper, can be performed more reliably. In this case as well, when separating the second sheet of paper, the three parameters that are increased compared to when separating the first sheet of paper may be all three: the pressing load, the rotational speed, and the limit torque. Alternatively, one or two of these may be selected and increased.

[0076] <<Separation setting W3>> Next, the separation setting W3 is a setting that changes depending on the difference in paper thickness, which is one of the conditions during paper feeding. Separation setting W3 increases the pressing load of the separation roller 15 when separating a second sheet of paper (second medium) which is relatively thicker than the first sheet of paper (first medium) in the media feeding device 10, compared to when separating the first sheet of paper. In other words, when separating a second sheet of paper that is relatively thicker (hereinafter simply referred to as "thick"), the pressing load of the separation roller 15 is increased compared to when separating a first sheet of paper that is relatively thinner than the second sheet (hereinafter simply referred to as "thin").

[0077] If the paper being fed is thick, it may be difficult for the paper to enter between the separation roller 15 and the feed roller 14, resulting in a non-feed state where the paper is not fed by the feed roller 14. Therefore, when separating the second sheet of paper, which is relatively thicker than the first sheet, the pressing load of the separation roller 15 is increased compared to when separating the first sheet (thin), thereby firmly nipping the second sheet between the separation roller 15 and the feed roller 14. This improves the feeding performance by the feed roller 14. As a result, the risk of the thicker second sheet not being fed is reduced.

[0078] As described above, by changing at least one of the following—the pressing load of the separation roller 15, the rotational speed of the separation roller 15, and the limit torque—depending on the feeding conditions, and setting different separation parameters, appropriate separation can be performed for a wider variety of paper types.

[0079] Refer to Figure 8 to summarize the case where paper is separated and fed in separation mode. After the separation mode is started, the separation setting is selected according to the conditions during paper feeding (step S1). If separation setting W1 (the paper to be separated is a second sheet of paper that is relatively thinner than the first sheet of paper) is selected, the pressing load, rotation speed, or limit torque is reduced compared to when separating the first sheet of paper (step S2). When separation setting W2 (where the paper to be separated is a second sheet of paper with relatively higher frictional force than the first sheet of paper) is selected, the pressing load, rotational speed, or limit torque is increased compared to when separating the first sheet of paper (step S3). If separation setting W3 (where the paper to be separated is a second sheet of paper that is relatively thicker than the first sheet of paper) is selected, the pressing load is increased compared to when separating the first sheet of paper (step S4). Depending on the separation setting, if the pressing load, rotation speed, or limit torque is changed, the paper (second sheet) is fed while the separation is performed by the separation roller 15. In addition to separation settings W1 to W3, it is also possible to set separation settings other than W1 to W3 as separation settings according to the conditions during paper feeding.

[0080] The separation settings for the separation roller 15 according to the feeding conditions can be configured such that, for example, the control unit 19 automatically selects the setting when the user inputs the type of paper P to the scanner 1 using the operation panel 7. Furthermore, the control unit 19 may be configured to have a mode for performing separation using predetermined separation settings (for example, the above-mentioned separation settings W1 to W3), and the user may determine the separation setting according to the type of paper P and input it using the operation panel 7 to instruct the control unit 19 which of the separation settings W1 to W3 to use for separation.

[0081] Furthermore, for example, the control unit 19 can be configured to determine the separation settings for subsequent sheets of paper P2, etc., that are fed after the preceding sheet of paper P1, based on the detection results of the second detection unit 22 and the double-feed detection unit 28 (both refer to Figure 3), which detect the paper P between the feeding roller 14 and the transport roller pair 16. For example, if the second detection unit 22 (Figure 3) does not detect the preceding paper P1 after a predetermined time has elapsed since the start of feeding by the feed roller 14, or after the feed roller 14 has been driven a predetermined amount, it is possible that the preceding paper P1 has not been fed. In such a case, the control unit 19 executes the separation mode of the separation setting W3 described above for the preceding paper P1 and subsequent paper P2 to be re-fed.

[0082] Furthermore, if a double feed is detected by the double feed detection unit 28 (Figure 3) during the feeding of the preceding paper P1, the preceding paper P1 and the subsequent paper P2 that was double-fed together with the preceding paper P1 are considered to be media with high frictional force. In such cases, the control unit 19 executes the separation mode of the separation setting W2 described above for the preceding paper P1 and subsequent paper P2 to be re-fed. In this way, the control unit 19 can be configured to determine the separation settings for the next separation mode by feeding back the conditions of the separation mode that previously resulted in an error.

[0083] <<Other configurations in the separation roller>> The separation roller 15 may be configured to be rotationally driven in the first rotation direction A (Figure 3) by the first drive source 25. The first rotation direction A is the rotation direction in which the separation roller 15 feeds the paper P downstream (towards the +Y direction).

[0084] Here, for example, if there are many sheets of paper P placed on the media placement unit 11, and the leading edges of the paper P are aligned in the Y-axis direction, as shown in the upper diagram of Figure 6, the leading edges of the paper P may have difficulty entering between the separation roller 15 and the feed roller 14, which can result in non-feeding. Furthermore, if the separation roller 15 is rotated in the second rotation direction B, which is the direction in which the separation roller 15 separates the paper, while the paper is in the state shown in the upper part of Figure 6, the upper part of the stacked paper P may curl up.

[0085] In this embodiment, the control unit 19 is configured to rotate the separation roller 15 in the first rotation direction A by a predetermined amount after feeding by the feeding roller 14 has started but before the separation mode is executed. The feeding roller 14 is also driven while the separation roller 15 is rotating in the first rotation direction A. As shown in the upper part of Figure 6, when the leading edges of multiple sheets of paper P are aligned in the Y-axis direction, and the feed roller 14 is rotated in the feeding direction while the separation roller 15 is rotated in the first rotation direction A, the leading edges of the multiple sheets of paper P are separated and offset, as shown in the middle part of Figure 6. From this state, if the feed roller 14 is kept rotating in the feeding direction and the separation roller 15 is rotated in the second rotation direction B, as shown in the lower part of Figure 6, the leading edge of the bottommost sheet of paper P (closest to the media placement section 11) can easily get between the separation roller 15 and the feed roller 14, ensuring that the paper P is reliably nipped between the separation roller 15 and the feed roller 14. This reduces the risk of the aforementioned problems such as non-feeding and paper curling.

[0086] Furthermore, the operation of rotating the separation roller 15 in the first rotation direction A before executing the separation mode does not always need to be performed when performing the separation mode. For example, a paper count detection unit may be provided on the media placement unit 11, and the operation may be performed only when it is detected that a predetermined number or more of paper P have been placed on the media placement unit 11.

[0087] Next, we will describe the torque changing means 40 for changing the limit torque of the separation roller 15 and the load changing means 60 for changing the pressing load of the separation roller 15. As mentioned above, the rotational speed of the separation roller 15 is changed by the control unit 19, which acts as a "speed changing means," controlling the drive of the first drive source 25 (Figure 4) that drives the separation roller 15.

[0088] ■■■Regarding Torque Adjustment Methods■■■ The torque changing means 40 for changing the limit torque of the torque limiter 41 will be described below with reference to Figures 5 and 7.

[0089] As shown in Figures 5 and 7, the torque limiter 41 is configured to include a first torque limiter 42 and a second torque limiter 43. In this embodiment, the performance (free-running torque) of the first torque limiter 42 and the second torque limiter 43 is the same. Let T1 be the respective free-running torque. The first torque limiter 42 and the second torque limiter 43 each have gear teeth formed on their outer circumferences, and they constitute part of the first gear train 31 of the power transmission mechanism 30. In other words, the first torque limiter 42 and the second torque limiter 43 are provided on the gears included in the power transmission mechanism 30 shown in Figure 5.

[0090] The torque changing means 40 is configured to include a switching unit 46 that switches between a state in which the rotational torque is applied to one of the first torque limiter 42 and the second torque limiter 43 (upper diagram in Figure 7) and a state in which the rotational torque is applied to both (lower diagram in Figure 7). More specifically, the second moving gear 36 included in the power transmission mechanism 30 shown in Figure 5 constitutes the switching section 46.

[0091] The second moving gear 36 is configured to slide in the device width direction, i.e., in the X-axis direction. In Figure 5, the solid line shows the second moving gear 36 in the +X direction, and the dotted line shows the second moving gear 36 in the -X direction. When the second moving gear 36 is positioned on the -X side (solid line in Figure 5), the second moving gear 36 engages with only the first torque limiter 42 of the two torque limiters 43 (upper diagram in Figure 7), resulting in rotational torque being applied to one of them (the first torque limiter 42). In this state, the limit torque T of the separation roller 15 includes only the free-spinning torque T1 of the first torque limiter 42, and does not include the free-spinning torque T1 of the second torque limiter 43.

[0092] Furthermore, when the second moving gear 36 is positioned on the +X side (dotted line in Figure 5), the second moving gear 36 engages with both the first torque limiter 42 and the second torque limiter 43 (lower diagram in Figure 7), resulting in rotational torque being applied to both the first torque limiter 42 and the second torque limiter 43. In this state, the limit torque T of the separation roller 15 includes both the free-running torque T1 of the first torque limiter 42 and the free-running torque T1 of the second torque limiter 43.

[0093] With the configuration of the torque changing means 40 as described above, the limit torque T of the separation roller 15 can be changed.

[0094] In this embodiment, the second moving gear 36, which serves as the switching unit 46, is rotatably held in a gear holder 44, as shown in Figure 7. The gear holder 44 is provided with a knob 45, which is exposed from the upper unit 4, as shown in Figures 1 and 2. The user can easily change the limit torque of the separation roller 15 by sliding the knob 45 in the X-axis direction. Furthermore, the movement of the second moving gear 36, which serves as the switching unit 46, in the X direction, i.e., the switching of the limit torque, is configured to be performed manually as described above. Alternatively, the movement of the second moving gear 36 in the X direction can be performed by an electromagnetic clutch or the like, and controlled by the control unit 19.

[0095] In this embodiment, the free-running torque of the first torque limiter 42 and the free-running torque of the second torque limiter 43 are set to the same T1, but they may be set to different torques (T1 and T2). In that case, configuring it as follows will broaden the range of change for the limit torque of the separation roller 15.

[0096] In other words, the torque changing means 40 includes a first torque limiter 42 with an idle torque T1 and a second torque limiter 43 with an idle torque T2 that is different from that of the first torque limiter 42. The second moving gear 36, which acts as a switching unit 46, is configured to switch between a state in which rotational torque is applied to the first torque limiter 42 by meshing only with the first torque limiter 42 (upper diagram in Figure 7) and a state in which rotational torque is applied to the second torque limiter 43 by meshing only with the second torque limiter 43 (not shown).

[0097] In other words, the torque changing means 40 is configured to include a switching unit 46 that switches between a state in which rotational torque is applied to the first torque limiter 42 and a state in which rotational torque is applied to the second torque limiter 43. With the above configuration, the limit torque T of the separation roller 15 can be easily changed between a state in which only T1 is included and a state in which only T2 is included. Furthermore, as mentioned above, if the second moving gear 36 is set to mesh with both the first torque limiter 42 and the second torque limiter 43 (lower diagram in Figure 7), rotational torque will be applied to both the first torque limiter 42 and the second torque limiter 43, and the limit torque T of the separation roller 15 can be set to include both T1 and T2.

[0098] ■■■Regarding Load Change Methods■■■ The load changing means 60 for changing the pressing load of the separation roller 15 will be described below with reference to Figure 9. The load changing means 60 is positioned between the spring support portion 61 and the separation roller 15 and includes a compression spring 62 that presses the separation roller 15 toward the feed roller 14. The spring length L of the compression spring 62 is changed by moving the spring support portion 61, thereby changing the pressing load of the separation roller 15 toward the feed roller.

[0099] More specifically, the separation roller 15 is rotatably supported by the roller holder 63, and the compression spring 62 is in contact with the roller holder 63. In other words, the compression spring 62 presses the separation roller 15 toward the feed roller 14 via the roller holder 63. The roller holding section 63 has a pivot shaft 64 that swings the held separation roller 15 toward and away from the feeding roller 14.

[0100] An eccentric cam 65 is provided above the spring support portion 61, and the spring support portion 61 is configured to move in the Z-axis direction as the eccentric cam 65 rotates around the rotation axis 66. In the eccentric cam 65, when the outermost part 65a closest to the rotation axis 66 contacts the spring support portion 61 (left diagram in Figure 9), the spring support portion 61 is positioned furthest towards the +Z direction. At this point, the spring length L of the compression spring 62 becomes the longest L1, and the compression load K is the smallest K1.

[0101] On the other hand, in the eccentric cam 65, when the outermost part 65b, which is furthest from the rotation axis 66, contacts the spring support part 61 (right diagram in Figure 9), the spring support part 61 is positioned furthest towards the -Z direction. At this point, the spring length L of the compression spring 62 becomes the shortest L2, and the compression load K at this time becomes the largest compression load K2. By rotating the eccentric cam 65, the pressing load K can be changed between pressing load K1 and pressing load K2.

[0102] The eccentric cam 65 is configured to rotate by receiving power from a drive source (not shown), and the rotation of the eccentric cam 65 is controlled by the control unit 19, which controls the rotation of the drive source (not shown). In other words, the control unit 19, which controls the rotational speed of the separation roller 15, controls at least one of the load changing means 60 or the torque changing means 40 (in this embodiment, the load changing means 60).

[0103] This allows the rotational speed of the separation roller 15 and the pressing load of the separation roller 15 to be changed automatically. In this embodiment, the limit torque T is changed by the user manually operating the torque changing means 40, but the operation of the torque changing means 40 can also be controlled by the control unit 19. This allows for automatic changes to the separation settings according to the feeding conditions when performing the separation mode.

[0104] ■■■Other examples of torque changing methods■■■ <<Example 1 of Torque Changing Mechanism Modification>> The torque changing means 50, which is an example of a modified torque changing means, will be described primarily with reference to Figures 10 and 11. The torque changing means 50 shown in Figures 10 and 11 includes a torque limiter 51 that causes the separation roller 15 to spin freely in the first rotation direction A (Figure 3) when the rotational torque applied to the separation roller 15 in the first rotation direction A exceeds a predetermined limit torque, and a power transmission mechanism 52 between the separation roller 15 and the separation roller 15. The power transmission mechanism 52 includes a first power transmission path 53 (left diagram in Figure 11), a second power transmission path 54 (right diagram in Figure 11) with a different reduction ratio from the first power transmission path 53, and a moving gear 55 as a "switching means" for switching between the first power transmission path 53 and the second power transmission path 54.

[0105] The configuration of the torque changing means 50 will be described in more detail below. The torque limiter 51 is provided on the gear 70. Power from the first drive source 25 (Figure 4) is transmitted to the shaft 51a of the torque limiter 51 by a power transmission mechanism such as a gear train (not shown). As shown in Figure 10, the power transmission mechanism 52 from the gear 70 on which the torque limiter 51 is provided to the separation roller 15 comprises a moving gear 55, a first gear 56, a second gear 57, a third gear 58, a fourth gear 59 (see Figure 11), a rotating shaft 71 on which the fourth gear 59 is provided, and a gear train 72 provided between the rotating shaft 71 and the rotating shaft 15a of the separation roller 15.

[0106] The movable gear 55 is configured to be movable in the X-axis direction and can be switched between a first state in which it meshes with the first gear 56, as shown in the left diagram of Figure 11, and a second state in which it meshes with the third gear 58, as shown in the right diagram of Figure 11. The reduction ratio when the moving gear 55 meshes with the first gear 56 (the reduction ratio when power is transmitted in the order of moving gear 55 → first gear 56 → second gear 57 → third gear 58 → fourth gear 59) and the reduction ratio when the moving gear 55 meshes with the third gear 58 (the reduction ratio when power is transmitted in the order of moving gear 55 → third gear 58 → fourth gear 59) are configured to have different reduction ratios from each other.

[0107] More specifically, in the first state (left diagram in Figure 11), the power (rotation) of gear 70 is transmitted in the following order: moving gear 55, first gear 56, second gear 57, third gear 58, fourth gear 59, rotating shaft 71, gear train 72, rotating shaft 15a, and separating roller 15. This power transmission path is the first power transmission path 53.

[0108] In the second state (right diagram in Figure 11), the power (rotation) of gear 70 is transmitted in the following order: moving gear 55, third gear 58, fourth gear 59, rotating shaft 71, gear train 72, rotating shaft 15a, and separating roller 15. This power transmission path is the second power transmission path 54.

[0109] The first power transmission path 53 (left diagram in Figure 11) and the second power transmission path 54 (right diagram in Figure 11) have different reduction ratios (they are configured in this way). As a result, the limit torque T1 of the separation roller 15 when power is transmitted by the first power transmission path 53 is different from the limit torque T2 of the separation roller 15 when power is transmitted by the second power transmission path 54. Therefore, by moving the moving gear 55, which acts as a "switching means," in the X-axis direction, the limit torque of the separation roller 15 can be switched from T1 to T2, or from T2 to T1, by switching between the first power transmission path 53 (left diagram in Figure 11) and the second power transmission path 54 (right diagram in Figure 11).

[0110] Furthermore, the switching between the first power transmission path 53 and the second power transmission path 54, which is performed by moving the moving gear 55 in the X-axis direction, may be done manually or automatically by the control unit 19.

[0111] <<Example 2 of Torque Changing Mechanism Modification>> The torque changing means 80, which is an example of a modified torque changing means, will be described primarily with reference to Figures 12 and 13. The torque changing mechanism 80 shown in Figure 12 includes a gear 81 and a torque limiter 83, which are mounted coaxially with the rotation axis 15a of the separation roller 15. The torque limiter 83 is configured to switch its performance (free-spinning torque) depending on whether the gear 81 is rotating forward or backward. As shown in Figure 13, the torque limiter 83 has a coil spring 87 inside.

[0112] The configuration of the torque changing means 80 will be described in more detail below. The upper diagrams in Figure 12 and Figure 13 show the gear 81 rotated in the direction of arrow C. The lower diagrams in Figure 12 and Figure 13 show the gear 81 rotated in the direction of arrow D. When the gear 81 is rotated in the direction of arrow C (upper diagram of Figure 12 and upper diagram of Figure 13), the torque changing means 80 enters a first state in which the main body 86 of the torque limiter 83 is connected to the connecting part 84 on the rotating shaft 15a side of the separation roller 15, and the shaft 82 of the torque limiter 83 is connected to the connecting part 85 on the gear 81 side. Furthermore, when the gear 81 is rotated in the direction of arrow D (lower diagram in Figure 12 and lower diagram in Figure 13), the torque changing means 80 enters a second state in which the main body 86 of the torque limiter 83 and the connecting part 85 on the gear 81 side are connected, and the shaft 82 of the torque limiter 83 and the connecting part 84 on the rotating shaft 15a side of the separation roller 15 are connected.

[0113] Furthermore, the diameter of the coil spring 87 of the torque limiter 83 is changed by switching between the first state and the second state. Changing the diameter of the coil spring 87 changes the frictional force between the coil spring 87 and the main body 86, thereby changing the performance (free-spinning torque) of the torque limiter 83.

[0114] ■■■Other examples of load changing methods■■■ <<Example 1 of modification of load changing mechanism>> Referring to Figure 14, an example of a modified load changing means, the load changing means 90, will be described. The load changing means 90 comprises a first coil spring 91 as a "first pressing part" and a second coil spring 92 as a "second pressing part" having a different pressing force from the first coil spring 91. The configuration is such that the pressing load K of the separation roller 15 against the feed roller 14 is changed by switching the spring (pressing part) that presses the separation roller 15 toward the feed roller 14 between the first coil spring 91 and the second coil spring 92. The first coil spring 91 and the second coil spring 92 are springs with different spring constants. The first coil spring 91 and the second coil spring 92 contact the roller holding portion 63 that holds the separation roller 15, and press the separation roller 15 through the roller holding portion 63.

[0115] The upper part of Figure 14 shows the state in which the first coil spring 91 is in contact with the roller holding part 63 and pressing against the separation roller 15. The lower part of Figure 14 shows the state in which the second coil spring 92 is in contact with the roller holding part 63 and pressing against the separation roller 15. The springs pressing the separation roller 15 can be switched using, for example, a rack and pinion mechanism 93. For example, in Figure 14, when the pinion 94 is rotated in the direction of arrow E, the first coil spring 91 goes down and the second coil spring 92 goes up. Conversely, when the pinion 94 is rotated in the direction of arrow F, the first coil spring 91 goes up and the second coil spring 92 goes down. The pressing load K when the separation roller 15 is pressed by the first coil spring 91 is K1, and the pressing load K when the separation roller 15 is pressed by the second coil spring 92 is K2.

[0116] The load changing means 90 described above also allows the pressing load K of the separation roller 15 against the feeding roller 14 to be changed between pressing load K1 and pressing load K2.

[0117] <<Example 2 of modifying the load changing mechanism>> Referring to Figure 15, an example of a modified load changing means, the load changing means 100, will be described. The media feeding device 10 includes a roller holding part 101 that rotatably holds the separation roller 15 and has a pivot shaft 102 that swings the held separation roller 15 toward and toward the feeding roller 14, and a pressing spring 103 that acts as a "pressing part" that presses the separation roller 15 toward the feeding roller 14 via the roller holding part 101. The load changing means 100 is configured to change the pressing load K of the separation roller 15 against the feeding roller 14 by moving the position of the pivot axis 102.

[0118] The pivot shaft 102 is configured to be displaceable between position α shown in the left diagram of Figure 15 and position β shown in the right diagram of Figure 15. When the position of the oscillating axis 102 changes, the angle θ formed by the tangent line between the separation roller 15 and the feeding roller 14 at the nip position N, and the line segment connecting the center of the oscillating axis 102 and the nip position N, changes. The pressing force applied by the compression spring 103 is decomposed as shown by arrows a, b, and c, depending on the angle θ. The smaller the angle θ, the greater the pressing load K (arrow c) on the feed roller 14 at the nip position N.

[0119] When the pivot axis 102 is at position α as shown in the left diagram of Figure 15, the angle θ is θ1, and the pressing load K at this time is K1. Also, when the pivot axis 102 is at position β as shown in the right diagram of Figure 15, the angle θ is θ2, and the pressing load K at this time is K2. The angle θ is θ1 < θ2, and therefore the pressing load K is K1 > K2.

[0120] The load changing means 100 described above allows the pressing load K of the separation roller 15 against the feeding roller 14 to be changed between pressing load K1 and pressing load K2.

[0121] <<Example 3 of modification of load changing mechanism>> Referring to Figure 16, an example of a modified load changing means, the load changing means 110, will be described. The media feeding device 10 includes a roller holding part 111 that rotatably holds the separation roller 15 and has a pivot shaft 112 that swings the held separation roller 15 toward and toward the feeding roller 14, and a pressing spring 113 that acts as a "pressing part" that presses the separation roller 15 toward the feeding roller 14 via the roller holding part 111. The load changing means 110, by contacting the roller holding portion 111, restricts the position of the separation roller 15 relative to the feed roller 14 against the pressing force of the compression spring 113, and also includes a displacement member 115 that can be displaced in a direction that changes the position of the separation roller 15 relative to the feed roller 14.

[0122] In Figure 16, the displacement member 115 is configured to be displaced in the Z-axis direction by a rack portion 116 integrally provided with the displacement member 115 and a pinion gear 117 that meshes with the rack portion 116. When the pinion gear 117 rotates in the direction of arrow G, the displacement member 115 is displaced upward (+Z direction), and when the pinion gear 117 rotates in the direction of arrow H, the displacement member 115 is displaced downward (-Z direction). The displacement member 115 contacts the contact portion 114 provided on the roller holding portion 111 from below, thereby regulating the position of the separation roller 15 relative to the feeding roller 14.

[0123] When the displacement member 115 is displaced upward, that is, in a direction that opposes the pressing force of the compression spring 113, the pressing load K of the separation roller 15 on the feed roller 14 decreases. When the displacement member 115 that has been displaced upward is returned to its downward position, the pressing load K increases. The load changing means 110 described above allows for easy modification of the pressing load K of the separation roller 15 against the feed roller 14.

[0124] <<Example 4 of modifications to the load changing mechanism>> Referring to Figure 17, an example of a modified load changing means, the load changing means 120, will be described. The media supply device 10 is provided with a power transmission mechanism 30A that transmits power from a first drive source 25 (not shown in Figure 17, see Figure 4) that drives the separation roller 15. The power transmission mechanism 30A includes a first gear 121 integrally mounted on the rotating shaft 15a of the separation roller 15, a second gear 122 integrally mounted on the rotating shaft 15a of the separation roller 15 and having a different reduction ratio from the first gear 121, and a switching gear 125 that is displaceable between a first position M1 (left diagram in Figure 17) that transmits power from the first drive source 25 to the first gear 121 and a second position M2 (right diagram in Figure 17) that transmits power from the first drive source 25 to the second gear 122. As an example, the reduction ratio R1 of the first gear 121 is set to be relatively lower than the reduction ratio R2 of the second gear 122 (R1 <R2)。 Furthermore, the power transmission mechanism from the first drive source 25 to the switching gear 125, which is not shown in Figure 17, can be constructed using a gear train or belt mechanism composed of multiple gears. The load changing means 120 is configured to change the pressing load K of the separation roller 15 against the feed roller 14 by switching the switching gear 125 between a first position M1 (left diagram in Figure 17) and a second position M2 (right diagram in Figure 17).

[0125] When the power transmission mechanism 30A transmits power from the first drive source 25 to the separation roller 15 and rotates the separation roller 15 in the second rotation direction B, the higher the reduction ratio of the gear integrally provided on the rotation axis 15a of the separation roller 15, the greater the lifting force (the force acting in the direction that moves the separation roller 15 away from the feed roller 14) applied to the separation roller 15 by the drive of the separation roller 15 tends to be. When the lifting force increases, the pressing load on the separation roller 15 decreases. Therefore, the pressing load K2 in the state shown in the right diagram of Figure 17, where the switching gear 125 is positioned in the second position M2 and power is transmitted to the rotating shaft 15a via the second gear 122 with a high reduction ratio R2, is smaller than the pressing load K1 in the state shown in the left diagram of Figure 17, where the switching gear 125 is positioned in the first position M1 and power is transmitted to the rotating shaft 15a via the first gear 121 with a low reduction ratio R1 (K1 > K2).

[0126] In such a load changing means 120, by switching the position of the switching gear 125 between a first position M1 and a second position M2, the pressing load K of the separation roller 15 against the feed roller 14 can be changed between pressing load K1 and pressing load K2.

[0127] Furthermore, when the control unit 19 switches the paper feeding control (including the separation settings described above) for each paper type, the user can select the paper type, i.e., the paper feeding control, by displaying a UI (user interface) on the display unit of the operation panel 7 and allowing the user to select through the UI, or by providing a hard switch for selecting the paper type on the front of the device where the operation panel 7 is located. This hard switch can be placed, for example, together with the power button. By providing such a hard switch, the user can directly select the paper type without opening a menu screen or the like. In addition, this hard switch may be configured to function as a scan execution button in addition to selecting the paper type.

[0128] Specifically, for example, it is possible to select from four types of paper: "document," "regular photo," "panoramic photo," and "instant photo." In this case, a hard switch is provided for each paper type, resulting in a total of four hard switches (hard switches for paper type selection) on the front of the device. Instant photos are photographs composed of multiple layers, such as Polaroid (a registered trademark of Polaroid Corporation), and if the separation roller 15 is set to the separated state for separation, the layers may separate, potentially causing damage. Therefore, in the case of instant photos, it is preferable to set the separation switching means 27 (Figure 5) described above to the "non-separated state" as the feeding control, and to set it to the "separated state" as described above for other paper types. By configuring the separation settings according to the paper type for each hard switch, proper separation can be achieved. Furthermore, since the feed control includes not only separation settings but also double-feed detection using the double-feed detection unit 28 (Figure 3) and jam detection, switching these settings to the appropriate ones according to the paper type will enable more precise transport.

[0129] Furthermore, it goes without saying that the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the invention as described in the claims, and these modifications are also included within the scope of the present invention.

[0130] For example, the media feeding device 10 described above can be installed not only in image reading devices but also in other devices. As one example, it can be installed in a recording device that records on the transported paper (medium). [Explanation of Symbols]

[0131] 1...Scanner (image reading device), 2...Main unit, 3...Lower unit, 4...Upper unit, 5...Output tray, 6...Paper feed slot, 7...Operation panel, 8...First auxiliary paper support, 9...Second auxiliary paper support, 10...Media feeding device, 11...Media placement section, 12...Edge guide, 13...Guide surface, 14...Feeding roller (feeding section), 15...Separation roller, 16...Conveyor roller pair, 17...Discharge roller pair, 18...Discharge port, 19...Control unit 20...Reading unit, 20a...Upper reading sensor, 20b...Lower reading sensor, 21...First detection unit, 22...Second detection unit, 23...Third detection unit, 24...Fourth detection unit, 25...First drive source, 26...Second drive source, 27...Separation switching means, 28...Double feed detection unit, 30...Power transmission mechanism, 31...First gear train, 32...Gear, 33...First moving gear, 34...Gear, 35...Gear, 36...Second moving gear, 40...Torque changing means, 41...Torque limiter, 42...First Torque limiter, 43... Second torque limiter, 50... Torque changing means, 52... Power transmission mechanism, 55... Moving gear (switching means), 56... First gear, 57... Second gear, 58... Third gear, 59... Fourth gear, 60... Load changing means, 61... Spring support part, 62... Compression spring, 63... Roller holding part, 64... Oscillating shaft, 65... Eccentric cam, 66... ​​Rotating shaft, 70... Gear, 71... Rotating shaft, 80... Torque changing means, 81... Gear, 83... Torque Limiter, 90...Load changing means, 91...First coil spring (first pressing part), 92...Second coil spring (second pressing part), 100...Load changing means, 101...Roller holding part, 102...Oscillating shaft, 103...Compression spring (compression part), 110...Load changing means, 111...Roller holding part, 113...Compression spring (compression part), 115...Displacement member, 120...Load changing means, 121...First gear, 122...Second gear, 125...Switching gear, P...Paper (medium)

Claims

1. First drive source and The second drive source and A reading unit that reads the media, A media mounting section on which the media is placed, A feeding roller, driven by the second drive source, feeds the medium from the medium placement section, A roller that nips the medium between itself and the feeding roller to separate the medium, wherein the separation roller is driven by a first drive source in a second rotational direction opposite to the first rotational direction that sends the medium downstream, A first torque limiter causes the separation roller to spin freely in the first rotational direction when the rotational torque applied to the separation roller in the first rotational direction exceeds a predetermined torque upper limit value, A second torque limiter causes the separation roller to spin freely in the first rotational direction when the rotational torque applied to the separation roller in the first rotational direction exceeds a predetermined torque upper limit value, A torque changing means for changing the limit torque of the separation roller, A speed changing means for changing the rotational speed of the first drive source, A pair of conveying rollers provided downstream of the aforementioned feeding rollers, A double-feed detection unit is provided between the feed roller and the pair of transport rollers in the transport path to detect double-feeding of the medium being fed, An image reading device comprising a control unit for controlling the first drive source and the second drive source, The separation roller is switchable between a separation state in which the medium is separated and a non-separation state in which the medium is not separated. The separation settings, which include the limit torque and the rotational speed, can be changed according to the conditions during feeding. The aforementioned separation setting is, When separating a second medium which is relatively thinner than the first medium, at least one of the limit torque and the rotational speed is suppressed compared to when separating the first medium. When separating a second medium having a relatively higher frictional force than the first medium, at least one of the limit torque and the rotational speed is increased compared to when separating the first medium. When a double feed is detected in the double feed detection unit, at least one of the limit torque and the rotational speed of the medium to be re-fed is increased compared to when the first medium is separated. An image reading device characterized by the following:

2. First drive source and The second drive source and A reading unit that reads the media, A media mounting section on which the media is placed, A feeding roller, driven by the second drive source, feeds the medium from the medium placement section, A roller that nips the medium between itself and the feeding roller to separate the medium, wherein the separation roller is driven by a first drive source in a second rotational direction opposite to the first rotational direction that sends the medium downstream, A first torque limiter causes the separation roller to spin freely in the first rotational direction when the rotational torque applied to the separation roller in the first rotational direction exceeds a predetermined torque upper limit value, A second torque limiter causes the separation roller to spin freely in the first rotational direction when the rotational torque applied to the separation roller in the first rotational direction exceeds a predetermined torque upper limit value, A torque changing means for changing the limit torque of the separation roller, A load changing means for changing the pressing load of the separation roller on the feeding roller, A pair of conveying rollers provided downstream of the aforementioned feeding rollers, A detection unit is provided between the feed roller and the pair of feed rollers in the transport path to detect the medium being fed, A double-feed detection unit is provided between the detection unit and the transport roller in the transport path to detect double-feeding of the medium being supplied, An image reading device comprising a control unit for controlling the first drive source and the second drive source, The separation roller is switchable between a separation state in which the medium is separated and a non-separation state in which the medium is not separated. The separation settings, which include the limit torque and the pressing load, can be changed according to the conditions during feeding. The aforementioned separation setting is, When separating a second medium which is relatively thinner than the first medium, at least one of the limit torque and the pressing load is suppressed compared to when separating the first medium. When separating a second medium having a relatively higher frictional force than the first medium, at least one of the limit torque and the pressing load is increased compared to when separating the first medium. When a double feed is detected in the double feed detection unit, at least one of the limit torque and the pressing load applied to the medium to be re-fed is increased compared to when the first medium is separated. When separating a second medium which is relatively thicker than the first medium, the pressing load is increased compared to when separating the first medium. If, after feeding by the feeding roller has started, after a predetermined time has elapsed, or after the feeding roller has been driven a predetermined amount, the detection unit does not detect the preceding medium, the pressing load on the medium to be fed again is increased compared to when separating the first medium. An image reading device characterized by the following:

3. In the image reading device according to claim 1 or claim 2, The torque changing means is It moves between a first position and a second position and has an engaging portion that can engage with at least one of the first torque limiter and the second torque limiter, A first rotational torque is applied at the first position, and a second rotational torque greater than the first rotational torque is applied at the second position. An image reading device characterized by the following:

4. In the image reading device according to claim 1, The separation roller has a load changing means for changing the pressing load on the feeding roller, The aforementioned separation setting is, When separating a second medium which is relatively thinner than the first medium, at least one of the pressing load, the limiting torque, and the rotational speed is suppressed compared to when separating the first medium. When separating a second medium having a relatively higher frictional force than the first medium, at least one of the pressing load, the limiting torque, and the rotational speed is increased compared to when separating the first medium. When a double feed is detected in the double feed detection unit, at least one of the pressing load, limit torque, and rotational speed applied to the medium to be re-fed is increased compared to when the first medium is separated. An image reading device characterized by the following:

5. In the image reading device according to claim 2 or claim 4, The load changing means comprises a first pressing portion and a second pressing portion having a different pressing force from the first pressing portion. The pressing load is changed by switching the pressing portion that presses the separation roller toward the feeding roller between the first pressing portion and the second pressing portion. An image reading device characterized by the following:

6. In the image reading device according to claim 2 or claim 4, The image reading device is characterized in that the load changing means comprises a pressing spring disposed between a spring support and the separation roller, which presses the separation roller toward the feeding roller, and the spring length of the pressing spring is changed by moving the spring support, thereby changing the pressing load.

7. In the image reading device according to claim 2 or claim 4, A roller holding unit that rotatably holds the separation roller and has a pivot shaft that swings the held separation roller toward and toward the feeding roller, The system includes a pressing section that presses the separation roller toward the feeding roller via the roller holding section, The image reading device is characterized in that the load changing means is configured to change the pressing load by moving the position of the pivot axis.

8. In the image reading device according to claim 2 or claim 4, A roller holding unit that rotatably holds the separation roller and has a pivot shaft that swings the held separation roller toward and toward the feeding roller, The system includes a pressing section that presses the separation roller toward the feeding roller via the roller holding section, The image reading device is characterized in that the load changing means restricts the position of the separating roller relative to the feeding roller against the pressing force of the pressing part by contacting the roller holding part, and includes a displacement member that can be displaced in a direction that changes the position of the separating roller relative to the feeding roller.

9. In the image reading device according to claim 2 or claim 4, It is equipped with a power transmission mechanism that transmits power from the first drive source, The power transmission mechanism includes a first gear integrally mounted on the rotating shaft of the separation roller, a second gear integrally mounted on the rotating shaft of the separation roller and having a different reduction ratio from the first gear, and a switching gear that is displaceable between a first position for transmitting power from the first drive source to the first gear and a second position for transmitting power from the first drive source to the second gear. The image reading device is characterized in that the load changing means is configured to change the pressing load by switching the switching gear between the first position and the second position.

Images