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 that feeds a document, and an image reading device that reads the document fed by the medium feeding device. [Background technology]

[0002] A scanner, which is an example of an image reading device, may be equipped 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 automatically feed and read multiple sheets of media. The medium feeding device may be configured to include a media tray on which multiple sheets of media are placed on a loading surface, a feeding roller that rotates in contact with the surface of the media set in the media tray to feed out the media, and a separation roller that comes into contact with the feeding roller to separate the media.

[0003] By the way, there are various kinds of media. For example, if the separation force of the separation roller is applied to thin paper, waste paper, or the like, which has low rigidity, there is a risk that the medium may be significantly damaged. For this reason, a medium feeding device has been proposed that is configured to be able to select between a separation mode in which separation is performed by the separation roller and a non-separation mode in which the medium is fed without separation by the separation roller, depending on the type of medium (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-188279 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional medium feeding device, the user can select whether or not to separate the media by the separation roller by selecting the separation mode or the non-separation mode, but the separation resistance of the media in the separation mode is set uniformly, so that even if the separation mode is selected, there are cases where the media cannot be separated properly depending on the type of media.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a medium feeding device that can more appropriately separate media, or an image reading device equipped with such a medium feeding device. [Means for solving the problem]

[0007] In order to solve the above problem, a medium feeding device according to a first aspect of the present invention comprises a medium loading section for loading a medium, a feed roller for feeding the medium from the medium loading section, a separation roller which nip the medium between the medium loading section and the feed roller to separate the medium, and to which a driving torque is applied by a driving source in a second rotation direction opposite to a first rotation direction which feeds the medium downstream, and a torque limiter which causes the separation roller to rotate freely in the first rotation direction when the rotational torque applied to the separation roller in the first rotation direction exceeds a limit torque which is a predetermined upper torque limit value, and is characterized in that it has a load changing means for changing the pressing load of the separation roller against the feed roller, a speed changing means for changing the rotational speed of the driving source, and a torque changing means for changing the limit torque, and is configured to be able to change separation settings consisting of the pressing load, the rotational speed, and the limit torque depending on the conditions during feeding.

[0008] According to this aspect, the separation settings including the pressure load, the rotation speed, and the limit torque can be changed depending on the conditions during feeding, so that the medium can be separated more appropriately. The "conditions during feeding" refers to at least one or a combination of all conditions that affect the separability, such as the type of medium, the number of sheets, etc.

[0009] A second aspect of the present invention is characterized in that, in the first aspect, the load change means includes a first pressing portion and a second pressing portion having a pressing force different from that of the first pressing portion, and is configured to change the pressing load of the separation roller against the feed roller by switching the pressing portion that presses the separation roller against the feed roller between the first pressing portion and the second pressing portion.

[0010] According to this aspect, the load changing means is configured to change the pressing load of the separation roller against the feed roller by switching the pressing section that presses the separation roller against the feed roller between the first pressing section and the second pressing section, and the pressing force of the separation roller against the feed roller can be changed by using the load changing means. The load changing means is configured to change the pressing load of the separation roller against the feed roller by switching the pressing section that presses the separation roller against the feed roller between the first pressing section and the second pressing section.

[0011] A third aspect of the present invention is characterized in that, in the first aspect, the load changing means is provided with a pressure spring arranged between a spring support portion and the separation roller and pressing the separation roller toward the feed roller, and the spring length of the pressure spring is changed by moving the spring support portion, thereby changing the pressing load of the separation roller against the feed roller.

[0012] According to this aspect, the load changing means is configured to change the pressing load of the separation roller against the feed roller by changing the spring length of the pressing spring, which is disposed between the spring support portion and the separation roller and presses the separation roller against the feed roller, by moving the spring support portion.

[0013] A fourth aspect of the present invention is characterized in that, in the first aspect, the device further comprises a roller holding section which rotatably holds the separation roller and has a swing shaft which swings the held separation roller towards and away from the feed roller, and a pressing section which presses the separation roller towards the feed roller via the roller holding section, and the load changing means is configured to change the pressing load of the separation roller against the feed roller by moving the position of the swing shaft.

[0014] According to this aspect, the pressure load of the separation roller against the feed roller can be changed by the load changing means configured to change the pressure load of the separation roller against the feed roller by moving the position of the oscillating axis of the roller holding part.

[0015] A fifth aspect of the present invention is characterized in that, in the first aspect, the device further comprises a roller holding section which rotatably holds the separation roller and has a swing axis which swings the held separation roller towards and away from the feed roller, and a pressing section which presses the separation roller towards the feed roller via the roller holding section, and the load change means abuts against the roller holding section to regulate the position of the separation roller relative to the feed roller against the pressing force of the pressing section, and comprises a displacement member which is displaceable in a direction in which the position of the separation roller relative to the feed roller changes.

[0016] According to this aspect, the pressing load of the separation roller against the feed roller can be changed by regulating the position of the separation roller relative to the feed roller, so that the pressing load of the separation roller against the feed roller can be easily changed.

[0017] A sixth aspect of the present invention is characterized in that, in the first aspect, the power transmission mechanism includes a first gear integrally formed on the rotation shaft of the separation roller, a second gear integrally formed on the rotation shaft of the separation roller and having a different reduction ratio from the first gear, and a switching gear that can be displaced between a first position at which the power of the driving source is transmitted to the first gear and a second position at which the power of the driving source is transmitted to the second gear, and the load change means is configured to change the pressing load of the separation roller against the feed roller by switching the switching gear between the first position and the second position.

[0018] According to this aspect, the pressing load of the separation roller against the feed roller can be changed by the load changing means configured to change the pressing load of the separation roller against the feed 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 idling torque from the first torque limiter, and the torque change 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 aspect, the torque change 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 limiters include a first torque limiter and a second torque limiter, and the torque change 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 of the first torque limiter and the second torque limiter. According to this aspect, the torque change means can be easily configured.

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

[0022] A tenth aspect of the present invention, in any one of the first to ninth aspects, is characterized in that the device further comprises a control unit as the speed change 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, in the tenth aspect, is characterized in that 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.

[0024] A twelfth aspect of the present invention is characterized in that, in the tenth or eleventh aspect, 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, and the control unit is capable of selecting, based on the type of medium being fed, a separation mode in which the separation roller is in the separation state and feeding is performed, or a non-separation mode in which the separation roller is in the non-separation state and feeding is performed.

[0025] According to this aspect, the control unit can select whether to feed in the separation mode or the non-separation mode depending on the type of medium, allowing a variety of media to be fed more appropriately.

[0026] A thirteenth aspect of the present invention is characterized in that, in the twelfth aspect, the separation roller can be rotationally driven in the first rotation direction by the driving source, and the control unit rotationally drives the separation roller in the first rotation direction a predetermined amount of rotation before executing the separation mode.

[0027] According to this aspect, the control unit rotates the separation roller a predetermined amount in the first rotation direction before executing the separation mode, thereby ensuring that the medium is nipped between the separation roller and the feed roller, thereby reducing the risk of the medium not being fed.

[0028] A 14th aspect of the present invention is characterized in that, in any of the first to 13th aspects, when separating a second medium which is relatively thinner than a first medium, at least one of the pressing load, the rotational speed, and the limit torque is suppressed compared to when separating the first medium.

[0029] According to the present aspect, when separating a second medium that is relatively thinner than a first medium, at least one of the pressing load, the rotational speed, and the limit torque is suppressed compared to when separating the first medium, thereby reducing the separation resistance caused by the separation roller and reducing the risk of damage to the second medium due to separation by the separation roller.

[0030] A 15th aspect of the present invention is characterized in that, in any of the 1st to 13th aspects, when separating a second medium having a relatively higher frictional force than a first medium, at least one of the pressure load, the rotational speed, and the limit torque is increased compared to when separating the first medium.

[0031] According to the present aspect, when separating a second medium having a relatively higher frictional force than a first medium, at least one of the pressing load, the rotational speed, and the limit torque is increased compared to when separating the first medium, thereby increasing the separation resistance by the separation roller, and more reliably separating the second medium having a higher frictional force, i.e., a medium that is difficult to separate.

[0032] A 16th aspect of the present invention is characterized in that, in any of the 1st to 13th aspects, when separating a second medium which is relatively thicker than a first medium, the pressure load is increased compared to when separating the first medium.

[0033] When the medium being fed is a second medium that is relatively thicker than the first medium, the medium may not be fed by the feed roller, resulting in a non-feed state. According to this aspect, when separating a second medium that is relatively thicker than a first medium, the pressing load is increased compared to when separating the first medium, so that the second medium can be firmly nipped between the separation roller and the feeding roller, thereby improving the feeding performance of the feeding roller. This reduces the risk of non-feeding of thick paper.

[0034] The image reading device of the 17th aspect of the present invention is characterized in that it comprises a reading unit that reads a medium, and a medium feeding device described in any one of claims 1 to 15 that feeds the medium toward the reading unit.

[0035] According to this aspect, in an image reading device including a medium feeding device that feeds a medium toward the reading unit, the same effects as any one of the first to sixteenth aspects can be obtained. [Brief description of the drawings]

[0036] [Figure 1] FIG. 1 is an external perspective view showing a scanner according to the present invention. [Diagram 2]FIG. 2 is a perspective view of the scanner according to the present invention, seen from an angle different from that of FIG. [Diagram 3] FIG. 2 is a side cross-sectional view showing a paper transport path in the scanner according to the present invention. [Figure 4] FIG. 1 is a block diagram showing a configuration of a scanner according to the present invention. [Diagram 5] 4 is a schematic diagram showing a part of a power transmission mechanism that transmits power from a first drive source to a separation roller. FIG. [Figure 6] 5A to 5C are diagrams illustrating the operation of a separation roller. [Figure 7] FIG. 4 is a perspective view illustrating a torque changing means. [Figure 8] 11 is a flowchart showing an example of a separation mode. [Figure 9] FIG. 4 is a schematic side view illustrating a load changing unit. [Figure 10] FIG. 13 is a perspective view illustrating a first modified example of the torque changing means. [Figure 11] FIG. 13 is an enlarged view of a main portion for explaining a first modified example of the torque changing means. [Figure 12] FIG. 11 is a perspective view illustrating a second modified example of the torque change means. [Figure 13] 13 is a cross-sectional view illustrating a second modified example of the torque change means. FIG. [Figure 14] FIG. 11 is a schematic diagram illustrating a first modified example of the load changing means. [Figure 15] FIG. 11 is a side view illustrating a second modified example of the load changing means. [Figure 16] FIG. 11 is a schematic diagram illustrating a third modified example of the load changing means. [Figure 17] FIG. 11 is a perspective view illustrating a fourth modified example of the load changing means. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

[0039] FIG. 10 is a perspective view illustrating a first modification of the torque changing means. FIG. 11 is an enlarged view of a main part illustrating the first modification of the torque changing means. FIG. 12 is a perspective view illustrating a second modification of the torque changing means. FIG. 13 is a cross-sectional view illustrating the second modification of the torque changing means. FIG. 14 is a schematic view illustrating the first modification of the load changing means. FIG. 15 is a side view illustrating the second modification of the load changing means. FIG. 16 is a schematic view illustrating a third modification of the load changing means. FIG. 17 is a perspective view illustrating a fourth modification of the load changing means.

[0040] In the XYZ coordinate system shown in each figure, 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 a direction that intersects with the Y direction and generally indicates a direction perpendicular to the surface of the transported paper. 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 top of the device (including the upper part, top surface, etc.), and the -Z direction side is the bottom of the device (including the lower part, bottom surface, etc.). The direction in which the paper is fed (the +Y direction side) is called the "downstream", and the opposite direction (the -Y direction side) is called the "upstream".

[0041] ■■■Scanner Overview■■■ A scanner 1 according to the present invention will be described below mainly with reference to FIGS. The scanner 1 shown in FIGS. 1 and 2 includes, inside a device body 2, a reading unit 20 (FIG. 3) that reads an image on a paper sheet P (medium). The device main body 2 is comprised of a lower unit 3 and an upper unit 4. The upper unit 4 is attached so as to be openable and closable with the downstream side in the paper transport direction as a pivot point with respect to the lower unit 3, and is configured so that the upper unit 4 can be opened by rotating it towards the front side of the device to expose the paper transport path for paper P, and maintenance processes such as removing paper jams and cleaning can be easily performed on the paper P.

[0042] A medium placement section 11 for placing paper P is provided on the rear side (−Y axis direction side) of the device main body 2. Reference numeral 11a denotes a placement surface 11a for the paper P. Inside the device body 2, a medium feeding device 10 (FIG. 3) that feeds paper P from a medium placement unit 11 toward a reading unit 20 is provided. In the scanner 1, the medium placement unit 11 is provided detachably with respect to the device body 2. The configuration of the medium feeding device 10 will be described later.

[0043] The medium placement section 11 is also provided with a pair of left and right edge guides 12, 12 having guide surfaces 13 that guide the side edges of the paper P in the width direction (X-axis direction) that intersects with the feeding direction (Y-axis 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, one edge guide 12 (for example, the +X side) moves in the X direction, and the other edge guide 12 (-X side) moves in the opposing direction. That is, in the medium placement unit 11, the paper P is aligned in the center in the width direction, and the feed roller 14 described later is provided in the central area in the width direction, so that the paper is fed by a so-called center paper feeding method. Fig. 1 shows the edge guides 12, 12 in the outermost position, and Fig. 2 shows the edge guides 12, 12 in the innermost position.

[0044] As shown in Fig. 1, the medium mounting section 11 is equipped with a first auxiliary paper support 8 and a second auxiliary paper support 9. The first auxiliary paper support 8 and the second auxiliary paper support 9 can be stored inside the medium mounting section 11 as shown in Fig. 2, and are configured to be able to be pulled out from the medium mounting section 11 as shown in Fig. 1, making the length of the mounting surface 11a adjustable.

[0045] The device body 2 is provided with an operation panel 7 on the front side of the upper unit 4, which serves as both an operation section for operating various reading settings and reading execution, and a display section for displaying the contents of the reading settings and the like. A feed opening 6 that leads to the inside of the device main body 2 is provided at the top of the upper unit 4, and paper P placed on the media loading section 11 is sent from the feed opening 6 toward a reading section 20 (Figure 3) provided inside the device main body 2. Further, on the front side of the lower unit 3, a paper discharge tray 5, which will be described later, is provided.

[0046] ■■■About the paper transport path in the scanner■■■ Next, the paper transport path in the scanner 1 will be described mainly with reference to Fig. 3. Note that the dotted line in Fig. 3 indicates the transport path of the paper P. In the scanner 1, a paper sheet P, which is an original, is fed toward a reading unit 20 by a medium feeding device 10.

[0047] In this embodiment, the medium feeding device 10 shown in Figure 3 is equipped with the above-mentioned medium loading section 11, a feed roller 14 that feeds the paper P from the medium loading section 11 toward the reading section 20, and a separation roller 15 that nips the paper P between the feed roller 14 and separates the paper P. In FIG. 3, the separation roller 15 is configured so that a driving torque is applied from a first driving source 25 (FIG. 4) described later in a second rotation direction B opposite to a first rotation direction A that sends the paper P downstream (+Y direction).

[0048] In addition, a torque limiter (torque limiter 41 in FIG. 7 is shown as an example) is provided that causes separation roller 15 to rotate freely in first rotation direction A when the rotational torque applied to separation roller 15 in first rotation direction A (FIG. 3) exceeds a limit torque, which is a predetermined upper torque limit value. The rotation torque in the first rotation direction A (FIG. 3) applied to the separation roller 15 is imparted by the feed roller 14 when no paper P is interposed between the separation roller 15 and the feed roller 14, and is imparted by the paper P when the paper P is interposed between the separation roller 15 and the feed roller 14. When the rotation torque in the first rotation direction A (FIG. 3) applied to the separation roller 15 exceeds the limit torque, the separation roller 15 rotates in the first rotation direction A (FIG. 3) due to the rotation torque received from the feed roller 14 or the paper P. In this specification, this is defined as the idling of the separation roller 15. This idling of the separation roller 15 occurs in a state where no paper P is interposed between the separation roller 15 and the feed roller 14, and in a state where the paper P is interposed between the separation roller 15 and the feed roller 14 but no double feeding occurs.

[0049] Then, for example, when multiple sheets of paper P are interposed between the separation roller 15 and the feed roller 14, that is, when double feeding occurs, the rotation torque in the first rotation direction A (FIG. 3) applied to the separation roller 15 falls below the limit torque, and the separation roller 15 rotates in the second rotation direction B (FIG. 3) by the drive torque received from the first drive source 25 (FIG. 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 "limit torque" in this specification does not mean the idling torque of the torque limiter itself, but the torque that is the boundary between whether separation roller 15 will rotate idly or not, and the lower the limit torque, the easier it is for separation roller 15 to rotate in the first rotation direction A (FIG. 3). Conversely, when the limit torque is high, the force required to rotate separation roller 15 in the first rotation direction A (FIG. 3) increases. The torque changing means described later is a means for changing this limit torque.

[0050] Furthermore, the medium feeding device 10 has a load changing means (an example is the load changing means 60 in FIG. 4) that changes the pressing load of the separation roller 15 against the feeding roller 14, a control unit 19 as a "speed changing means" that changes the rotational speed of the first driving source that serves as the "driving source" that drives the separation roller 15, and a torque changing means (an example is the torque changing means 40 in FIG. 4) that changes the limit torque. The control unit 19 controls the driving of a first driving source 25 (FIG. 4) serving as a driving source for the separation roller 15, and is capable of changing the rotation speed of the separation roller 15.

[0051] The medium feeding device 10 is configured to be able to change the separation settings, which include the pressure load, the rotation speed, and the limit torque, depending on the conditions when the feeding roller 14 feeds the paper. A specific example of changing the separation setting, the configuration of the load changing means 60, and the configurations of the torque limiter 41 and the torque changing means 40 will be described in detail later.

[0052] The feed rollers 14 are provided as a pair in the central region in the width direction (X-axis direction) intersecting with the medium feed direction (+Y direction). A separation roller 15 is provided at a position facing the feed roller 14. As shown in FIG. 5, the separation rollers 15 are also provided as a pair corresponding to the feed rollers 14.

[0053] The paper P placed on the medium loading section 11 is picked up by a feed roller 14 rotatably provided with respect to the lower unit 3 and fed downstream (+Y direction). Specifically, the feed roller 14 feeds the paper P downstream by rotating while contacting the surface of the paper P facing the medium loading section 11. Therefore, when multiple sheets of paper P are set on the medium loading section 11 in the scanner 1, the paper P is fed downstream in order starting from the paper P on the loading surface 11a side.

[0054] On the downstream side of the feed roller 14, a transport roller pair 16, a reading unit 20, and a discharge roller pair 17 are provided. The transport roller pair 16 is provided 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 includes a transport drive roller 16a and a transport driven roller 16b.

[0055] A double feed detection unit 28 that detects double feed 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 including a transmitter that emits ultrasonic waves and a receiver that is provided opposite the transmitter with the transported paper therebetween can be used.

[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 image sensor module (CISM) as an example.

[0057] After the image on at least one of the front and back sides of the paper P is read by the reading unit 20, the paper P is nipped by a discharge roller pair 17 located downstream of the reading unit 20 and discharged from a discharge opening 18 provided on the front side of the lower unit 3. The discharge roller pair 17 is configured to include a discharge drive roller 17a and a discharge driven roller 17b.

[0058] In this embodiment, the feed roller 14, the separation roller 15, the transport drive roller 16a, and the discharge drive roller 17a are rotated by at least one drive source provided in the lower unit 3. As described above, the separation roller 15 is rotationally driven by the first drive source 25 (FIG. 4). In this embodiment, the transport drive roller 16a and the discharge drive roller 17a are also driven by a first drive source 25 common to the separation roller 15. The feed roller 14 is driven by a second drive source 26 separate from the first drive source 25.

[0059] 4, the operations of the first drive source 25 and the second drive source 26 are controlled by the control unit 19, which controls 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 feed 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 discharge port 18 toward the front side of the device. The paper output tray 5 can be stored in the bottom of the lower unit 3 (FIG. 1) or pulled out to the front side of the device (not shown). When the paper output tray 5 is pulled out, the paper P discharged from the discharge port 18 can be stacked on the paper output tray 5.

[0061] As shown in Fig. 3, a first detection unit 21 that detects the presence or absence of paper P placed on the medium placement unit 11 is provided upstream of the feed roller 14 in the medium feeding direction and within a paper placement area by the medium placement unit 11. 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, in that order. The second detection unit 22, the third detection unit 23, and the fourth detection unit 24 can detect the position of the paper P in the medium feeding direction. Also, it is possible to configure the device so that any of the second detection unit 22, the third detection unit 23, and the fourth detection unit 24 detects skew (oblique movement) of the paper P being fed. In this embodiment, the first detection section 21, the second detection section 22, the third detection section 23, and the fourth detection section 24 are provided in the central region in the width direction.

[0062] In addition, in this embodiment, the first detection unit 21, the second detection unit 22, the third detection unit 23, and the fourth detection unit 24 use optical sensors that have a light-emitting unit (not shown) that emits light and a light-receiving unit (not shown) that receives reflected light of the light emitted from the light-emitting unit. In addition to the optical sensor, ultrasonic sensors each having a transmitter that emits ultrasonic waves and a receiver that faces the transmitter across the transported paper can be used for the first detection unit 21 to the fourth detection unit 24. Also, a lever sensor that optically or electrically detects the displacement of a mechanical lever that is moved by contact with the transported paper can be used.

[0063] ■■■About paper separation when feeding with the media feeder■■■ ◆◆Isolated mode and non-isolated mode◆◆ First, in the medium 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 the paper P from the medium loading unit 11, the control unit 19 can select a separation mode in which the separation roller 15 is in the separation state and feeding is performed, or a non-separation mode in which the separation roller 15 is in the non-separation state and feeding is performed. The separation roller 15 is switched between the separation state and the non-separation state by a separation switching means 27 shown in Fig. 5. The separation switching means 27 is provided in a power transmission mechanism 30 that transmits power from the first drive source 25.

[0064] 5 shows the first gear train 31 which constitutes a part of the power transmission mechanism 30. The first gear train 31 is configured to include a gear 32, a first moving gear 33 which serves as the separation switching means 27, a gear 34, a gear 35, a second moving gear 36, and a torque limiter 41 which has teeth on its periphery. The second moving gear 36 and the torque limiter 41 are components which constitute the torque changing means 40 which will be described later.

[0065] The gear 32 shown in Fig. 5 is connected to a rotation shaft 37 of the transport drive roller 16a of the transport roller pair 16 (not shown in Fig. 5), and is configured to receive power from the first drive source 25 via the transport roller pair 16 (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. Of the power transmission mechanism 30, the transmission mechanism from the first drive source 25 to the conveying roller pair 16 is omitted, but like the first gear train 31, it can be configured using a gear train or belt mechanism made up of multiple gears.

[0066] Here, the first moving gear 33 is provided so as to be displaceable in the X-axis direction between a position shown by a solid line in Fig. 5 and a position shown by a dotted line in Fig. 5. At the position shown by the dotted line in Fig. 5, the first moving gear 33 meshes with the gears 32 and 34, and the driving force of the first driving source 25 (Fig. 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 a "separation state" in which the paper P is separated. 5, the first movable gear 33 is not engaged with the gears 32 and 34, and the driving force of the first drive source 25 is not transmitted to the separation roller 15. This state is called a "non-separation state" in which the paper P is not separated. In the non-separation state, the separation roller 15 is able to rotate freely with a small 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) or the like 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 "separation state" and the "non-separation state" by the separation switching means 27, the control unit 19 determines whether to feed in the separation mode or the non-separation mode based on, for example, the type of paper P set on the operation panel 7. The non-separation mode is selected, for example, when feeding paper that would be damaged if separated by the separation roller 15 (such as paper whose surface is made up of multiple layers, such as instant photographs, and the layers tend to peel off), or booklets such as bankbooks and passports. By selecting whether to perform feeding in the separation mode or the non-separation mode depending on the type of paper P, various types of paper P can be fed appropriately. It is also possible for the user to determine whether feeding is to be performed in the separation mode or the non-separation mode, and to manually switch between the "separation state" and the "non-separation state" by the separation switching means 27. In this case, it is preferable to provide a sensor or the like that detects whether the separation switching means 27 is set to the separation mode or the non-separation mode, so that the control unit 19 can grasp in which state the separation switching means 27 is currently in. Alternatively, a configuration may be adopted in which the user selects the separation mode or the non-separation mode using the operation panel 7, and the control unit 19 switches between the "separation state" and the "non-separation state."

[0069] Furthermore, when feeding in separation mode, the medium feeding device 10 is configured to be able to change the separation setting according to the feeding conditions as described above. The feeding conditions refer to at least one or a combination of all conditions that affect the separability, such as the type of paper and the number of sheets placed on the medium placement unit 11. The separation settings in the separation mode include the pressure load of the separation roller 15 against the feed roller 14 , the rotation speed of the separation roller 15 , and the limit torque of the separation roller 15 . Specific separation settings in the separation mode will be described below. Note that various change means (torque change means 40 and load change means 60) for changing the separation settings will be described after explaining specific examples of the separation settings.

[0070] About separation settings in separation mode <<Separation setting W1>> The separation setting W1 is a setting that is changed according to differences in paper thickness among the conditions during feeding. In the medium feeding device 10, when separating a second sheet (second medium) that is relatively thinner than a first sheet (first medium), the separation setting W1 reduces at least one of the pressure load of the separation roller 15, the rotation speed of the separation roller 15, and the limit torque of the separation roller 15 compared to when separating the first sheet.

[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 performed: reducing the pressure load of separation roller 15, slowing down the rotation speed of separation roller 15, and / or reducing the limit torque, compared to when separating a first sheet of paper that is relatively thicker than the second sheet of paper (hereinafter simply referred to as thick).

[0072] Separation of the paper by the separation roller 15 can usually be ensured by increasing the separation resistance between the separation roller 15 and the feed roller 14 to a certain degree. The "separation resistance" referred to here is determined by a combination of the pressure load of the separation roller 15, the rotation speed of the separation roller 15, and the limit torque of the separation roller 15. For example, the separation resistance increases when the pressure load of the separation roller 15 is increased, the separation resistance increases when the rotation speed of the separation roller 15 is increased, and the separation resistance increases when the limit torque of the separation roller 15 is increased. However, a thin second sheet of paper tends to have low rigidity, and if the separation resistance is too large, there is a risk that the second sheet of paper will tear or wrinkle.

[0073] When separating the second paper (thin), at least one of the pressure load of the separation roller 15, the rotation speed of the separation roller 15, and the limit torque of the separation roller 15 is suppressed compared to when separating the first paper (thick), so that the separation resistance when separating the second paper (thin) can be made smaller than when separating the first paper (thick). This can reduce the risk of damage such as tears and wrinkles occurring to the thin second paper due to separation by the separation roller 15. When separating the second sheet, the pressure load, the rotational speed, and the limit torque may all be suppressed compared to when separating the first sheet, or one or two of them may be selected and suppressed.

[0074] <<Separation setting W2>> Next, the separation setting W2 is a setting that is changed according to differences in the frictional force of the paper, among other conditions during feeding. The frictional force of the paper here is synonymous with the frictional force between sheets of paper. In the medium feeding device 10, when separating a second sheet (second medium) having a relatively higher frictional force than a first sheet (first medium), the separation setting W2 increases at least one of the pressure load, the rotational speed, and the limit torque compared to when separating the first sheet. That is, when separating the second sheet, at least one of the following is performed, compared to when separating the first sheet: the pressure load of separation roller 15 is increased, the rotation speed of separation roller 15 is increased, or the limit torque is increased.

[0075] When separating paper with high friction, if the separation resistance between the separation roller 15 and the feed roller 14 is small, separation is not possible, and feeding by the feed roller 14 may not be performed, resulting in a non-feed state. One example of paper with high friction is photo paper with a coating layer on the printing surface. In contrast, plain paper without a coating layer has a relatively low friction. Here, when separating a second sheet of paper having a relatively high frictional force (hereinafter referred to as high friction) from a first sheet of paper having a relatively low frictional force (hereinafter referred to as low friction), at least one of the pressing load, the rotational speed, and the limit torque is increased compared to when separating the first sheet of paper (low friction), so that when separating the second sheet of paper having high friction, the separation resistance by separation roller 15 is made larger than when separating the first sheet of paper having low friction, thereby improving separation performance. This makes it possible to more reliably separate the second sheet of paper having high frictional force, i.e., paper that is difficult to separate. In this case, when separating the second sheet, the pressing load, the rotational speed, and the limit torque may all be increased compared to when separating the first sheet, or one or two of them may be selected and increased.

[0076] <<Separation setting W3>> Next, the separation setting W3 is a setting that is changed according to differences in paper thickness among the conditions during feeding. The separation setting W3 increases the pressure load of the separation roller 15 when separating a second sheet (second medium) that is relatively thicker than a first sheet (first medium) in the medium feeding device 10 compared to when separating the first sheet. In other words, when separating a second sheet of paper that is relatively thick (hereinafter simply referred to as thick), the pressure load of separation roller 15 is increased more than when separating a first sheet of paper that is relatively thinner than the second sheet of paper (hereinafter simply referred to as thin).

[0077] If the paper to be fed is thick, it may be difficult for the paper to enter between separation roller 15 and feed roller 14, and the paper may not be fed by feed roller 14, resulting in a non-feed state. Therefore, when separating the second paper that is relatively thicker than the first paper, the pressure load of the separation roller 15 is increased compared to when separating the first paper (thin), so that the second paper can be firmly nipped between the separation roller 15 and the feed roller 14. This improves the feeding performance of the feed roller 14. This reduces the risk of non-feeding of the thick second paper.

[0078] As described above, by changing at least one of the pressure load of separation roller 15, the rotation speed of separation roller 15, and the limit torque according to the feeding conditions and setting different separation settings, appropriate separation can be performed for a greater variety of paper types.

[0079] The case where the sheets are separated and fed in the separation mode will be summarized with reference to FIG. After the separation mode is started, a separation setting is selected according to the conditions for paper feeding (step S1). When separation setting W1 (where the paper to be separated is a second paper that is relatively thinner than the first paper) is selected, any one of the pressing load, the rotation speed, and the limit torque is suppressed compared to when separating the first paper (step S2). When separation setting W2 (where the paper to be separated is a second paper having a relatively higher frictional force than the first paper) is selected, any one of the pressure load, rotation speed, and limit torque is increased compared to when separating the first paper (step S3). When separation setting W3 (where the sheet to be separated is a second sheet that is relatively thicker than the first sheet) is selected, the pressure load is increased compared to when separating the first sheet (step S4). After changing any one of the pressing load, the rotation speed, and the limit torque according to each separation setting, the paper (second paper) is fed while separation is being performed by the separation roller 15. It is also possible to set separation settings other than W1 to W3 as separation settings according to conditions when feeding paper.

[0080] The separation settings of the separation roller 15 according to the conditions during feeding can be configured to be automatically selected by the control unit 19, for example, when the user inputs the type of paper P to the scanner 1 using the operation panel 7. In addition, the control unit 19 can be configured to have a mode in which separation is performed using a predetermined separation setting (for example, the above-mentioned separation settings W1 to W3), and the user can determine the separation setting according to the type of paper P and input it using the operation panel 7, thereby instructing the control unit 19 which of the separation settings W1 to W3 to use for separation.

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

[0082] Furthermore, if the multi-feed detection unit 28 (FIG. 3) detects a multi-feed when the preceding sheet P1 is fed, the preceding sheet P1 and the succeeding sheet P2 that is fed together with the preceding sheet P1 are considered to be media with high friction. In such a case, the control unit 19 executes the separation mode of the separation setting W2 described above for the preceding sheet P1 and succeeding sheet P2 to be fed again. In this manner, the control unit 19 can be configured to determine the separation settings for the next separation mode by feeding back the separation setting conditions for the previous separation mode that resulted in an error.

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

[0084] Here, for example, when a large number of sheets of paper P are placed on the medium loading section 11, if the leading edges of the sheets of paper P are aligned in the Y-axis direction, as shown in the upper diagram of Figure 6, it may be difficult for the leading edges of the sheets of paper P to enter between the separation roller 15 and the feed roller 14, which may result in a non-feed. Furthermore, if separation roller 15 is rotated in the second rotation direction B, which is the direction in which separation roller 15 separates the paper, while the state is as shown in the upper figure of Figure 6, the upper paper P among the stacked papers may be turned over.

[0085] Here, in this embodiment, the control unit 19 is configured to rotate the separation roller 15 a predetermined rotation amount in the first rotation direction A after the start of feeding by the feed roller 14 and before the separation mode is executed. Note that while the separation roller 15 is rotated in the first rotation direction A, the feed roller 14 is also driven. As shown in the upper diagram of Fig. 6, when the leading ends of multiple sheets of paper P are aligned in the Y-axis direction, and the feed roller 14 is rotated in the feed direction while the separation roller 15 is rotated in the first rotation direction A, the leading ends of multiple sheets of paper P are shifted and separated, as shown in the middle diagram of Fig. 6. When the feed roller 14 is rotated in the feed direction from this state and the separation roller 15 is rotated in the second rotation direction B, the leading end of the bottommost sheet of paper P (closest to the medium placement unit 11) easily enters between the separation roller 15 and the feed roller 14, as shown in the lower diagram of Fig. 6, and the sheet of paper P can be reliably nipped between the separation roller 15 and the feed roller 14. This reduces the risk of the above-mentioned non-feed and paper turnover problems occurring.

[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 unit for detecting the number of sheets of paper P placed on the medium loading section 11 may be provided, and the operation may be performed only when it is detected that a predetermined number or more of sheets of paper P have been placed on the medium loading section 11.

[0087] Next, we will explain the torque changing means 40 that changes the limit torque of the separation roller 15, and the load changing means 60 that changes the pressing load of the separation roller 15. As described above, the rotation speed of the separation roller 15 is changed by the control unit 19, which serves as the "speed changing means", controlling the drive of the first drive source 25 (FIG. 4) that drives the separation roller 15.

[0088] ■■■Methods for changing torque■■■ The torque change means 40 for changing the limit torque of the torque limiter 41 will be described below with reference to FIGS.

[0089] 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 (idling torque) of each of the first torque limiter 42 and the second torque limiter 43 is the same. Each idling torque is designated as T1. The first torque limiter 42 and the second torque limiter 43 have gear teeth formed on their outer peripheries, and constitute a 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 gears included in the power transmission mechanism 30 shown in FIG.

[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 FIG. 7) and a state in which the rotational torque is applied to both of them (lower diagram in FIG. 7). More specifically, the second moving gear 36 included in the power transmission mechanism 30 shown in FIG.

[0091] The second moving gear 36 is configured to be slidable in the device width direction, i.e., in the X-axis direction. In Fig. 5, the second moving gear 36 shown by the solid line is positioned on the +X direction side, and the second moving gear 36 shown by the dotted line is positioned on the -X direction side. When the second movable gear 36 is positioned on the -X direction side (solid line in Figure 5), the second movable gear 36 is in a state in which it meshes with only the first torque limiter 42 of the first torque limiter 42 and the second torque limiter 43 serving as the torque limiter 41 (upper diagram in Figure 7), and a rotational torque is 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 idling torque T1 of the first torque limiter 42 and does not include the idling torque T1 of the second torque limiter 43.

[0092] Furthermore, when the second moving gear 36 is positioned on the +X direction side (dotted line in Figure 5), the second moving gear 36 is in mesh with both the first torque limiter 42 and the second torque limiter 43 (lower diagram in Figure 7), and a rotational torque is 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 idling torque T1 of the first torque limiter 42 and the idling torque T1 of the second torque limiter 43.

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

[0094] In this embodiment, the second movable gear 36 serving as the switching unit 46 is rotatably held by a gear holder 44 as shown in Fig. 7. The gear holder 44 is provided with a knob portion 45, which is exposed from the upper unit 4 as shown in Figs. 1 and 2. The user can easily change the limit torque of the separation roller 15 by sliding the knob portion 45 in the X-axis direction. In addition, the movement of the second moving gear 36 in the X direction as the switching unit 46, i.e., the switching of the limit torque, can be configured to be performed manually as described above, or 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 idling torque of the first torque limiter 42 and the idling torque of the second torque limiter 43 are the same T1, but they may be different torques (T1 and T2). In that case, the limit torque of the separation roller 15 can be changed in a wider range by configuring as follows.

[0096] That is, the torque change means 40 includes a first torque limiter 42 with an idling torque T1 and a second torque limiter 43 with an idling torque T2 that is different from the idling torque of the first torque limiter 42, and is configured to switch between a state in which the second moving gear 36 as the switching unit 46 meshes only with the first torque limiter 42 (upper diagram in Figure 7) and a rotational torque is applied to the first torque limiter 42, and a state in which the second moving gear 36 as the switching unit 46 meshes only with the second torque limiter 43 (not shown) and a rotational torque is applied to the second torque limiter 43.

[0097] In other words, the torque change means 40 is configured to include a switching unit 46 that switches between a state in which a rotational torque is applied to the first torque limiter 42 and a state in which a 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 described above, if the second movable gear 36 is brought into meshing engagement with both the first torque limiter 42 and the second torque limiter 43 (lower diagram in FIG. 7), a state in which a rotational torque is applied to both the first torque limiter 42 and the second torque limiter 43 is reached, and the limit torque T of the separation roller 15 can be brought into a state in which both T1 and T2 are included.

[0098] ■■■About load change methods■■■ Hereinafter, the load changing means 60 for changing the pressing load of the separation roller 15 will be described with reference to FIG. The load changing means 60 is provided with a pressure spring 62 disposed between the spring support portion 61 and the separation roller 15 and pressing the separation roller 15 towards the feed roller 14, and is configured to change the spring length L of the pressure spring 62 by moving the spring support portion 61, thereby changing the pressing load of the separation roller 15 against the feed roller.

[0099] More specifically, the separation roller 15 is rotatably supported by a roller holding portion 63, and the pressure spring 62 is in contact with the roller holding portion 63. In other words, the pressure spring 62 presses the separation roller 15 toward the feed roller 14 via the roller holding portion 63. The roller holding portion 63 has a swing shaft 64 that swings the held separation roller 15 so as to move it toward and away from the feed 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 by the eccentric cam 65 rotating about a rotation shaft 66. In the eccentric cam 65, when the part 65a of the outer periphery closest to the rotation shaft 66 comes into contact with the spring support part 61 (the left diagram in FIG. 9), the spring support part 61 is located closest to the +Z direction side. Then, the spring length L of the pressure spring 62 becomes the longest L1, and the pressure load K at this time becomes the smallest pressure load K1.

[0101] On the other hand, when the outer peripheral portion 65b of the eccentric cam 65, which is farthest from the rotation shaft 66, comes into contact with the spring support portion 61 (the right diagram in FIG. 9), the spring support portion 61 is located closest to the -Z direction side. Then, the spring length L of the pressure spring 62 becomes the shortest L2, and the pressure load K at this time becomes the largest pressure load K2. By rotating the eccentric cam 65, the pressing load K can be changed between a pressing load K1 and a 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 drive source (not shown) is controlled by the control unit 19, whereby the rotation of the eccentric cam 65 is controlled. In other words, the control unit 19, which controls the rotation speed of the separation roller 15, controls at least one of the load changing means 60 and the torque changing means 40 (in this embodiment, the load changing means 60).

[0103] This makes it possible to automatically change the rotation speed of the separation roller 15 and the pressure load of the separation roller 15. 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. Thus, when performing the separation mode, the separation settings can be automatically changed according to the feeding conditions.

[0104] ■■■Other examples of torque change methods■■■ <<Torque change method modification example 1>> Torque changing means 50, which is a modification of the torque changing means, will be described mainly with reference to FIGS. The torque change means 50 shown in Figures 10 and 11 includes a torque limiter 51 that causes the separation roller 15 to rotate freely in the first rotation direction A when the rotational torque applied to the separation roller 15 in the first rotation direction A (Figure 3) exceeds a predetermined limit torque, and a power transmission mechanism 52 between the separation roller 15, and 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) having a different reduction ratio from the first power transmission path 53, and a movable gear 55 as a "switching means" that switches 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. The power of the first driving source 25 (FIG. 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 FIG. 10, the power transmission mechanism 52 from the gear 70 on which the torque limiter 51 is mounted to the separation roller 15 includes a movable gear 55, a first gear 56, a second gear 57, a third gear 58, a fourth gear 59 (see FIG. 11), a rotating shaft 71 on which the fourth gear 59 is mounted, 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 figure of Figure 11, and a second state in which it meshes with the third gear 58 as shown in the right figure of Figure 11. The reduction ratio when the movable gear 55 meshes with the first gear 56 (the reduction ratio when power is transmitted in the order of movable gear 55 → first gear 56 → second gear 57 → third gear 58 → fourth gear 59) is different from the reduction ratio when the movable gear 55 meshes with the third gear 58 (the reduction ratio when power is transmitted in the order of movable gear 55 → third gear 58 → fourth gear 59).

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

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

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

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

[0111] <<Torque change method modification example 2>> Torque changing means 80, which is a modification of the torque changing means, will now be described with reference mainly to FIGS. The torque change means 80 shown in Fig. 12 includes a gear 81 and a torque limiter 83 that are provided coaxially with the rotation shaft 15a of the separation roller 15. The torque limiter 83 is configured such that its performance (idling torque) changes depending on whether the gear 81 is rotated forward or backward. The torque limiter 83 includes a coil spring 87 therein, as shown in Fig. 13.

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

[0113] By switching between the first state and the second state, the diameter of the coil spring 87 of the torque limiter 83 is changed. When the diameter of the coil spring 87 is changed, the frictional force between the coil spring 87 and the main body 86 is changed, so that the performance (idling torque) of the torque limiter 83 can be changed.

[0114] ■■■Other examples of load change methods■■■ <<Modification example 1 of load change method>> With reference to FIG. 14, a load changing means 90 which is a modification of the load changing means will be described. The load changing means 90 is characterized in that it includes a first coil spring 91 as a "first pressing portion" and a second coil spring 92 as a "second pressing portion" having a different pressing force from that of the first coil spring 91, and is configured to change the pressing load K of the separation roller 15 against the feed roller 14 by switching the spring (pressing portion) that presses the separation roller 15 against 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 come into contact with the roller holding portion 63 that holds the separation roller 15 , and press the separation roller 15 via the roller holding portion 63 .

[0115] 14 shows a state in which the first coil spring 91 is in contact with the roller holding portion 63 and pressing against the separation roller 15. The lower diagram of Fig. 14 shows a state in which the second coil spring 92 is in contact with the roller holding portion 63 and pressing against the separation roller 15. The spring that presses the separation roller 15 can be switched, for example, by using a rack and pinion mechanism 93. For example, in Fig. 14, when the pinion 94 is rotated in the direction of the arrow E, the first coil spring 91 is lowered and the second coil spring 92 is raised. Conversely, when the pinion 94 is rotated in the direction of the arrow F, the first coil spring 91 is raised and the second coil spring 92 is lowered. When the separation roller 15 is pressed by the first coil spring 91, the pressure load K is K1, and when the separation roller 15 is pressed by the second coil spring 92, the pressure load K is K2.

[0116] The load changing means 90 as described above can also change the pressing load K of the separation roller 15 against the feed roller 14 between the pressing load K1 and the pressing load K2.

[0117] <<Modification example 2 of load change method>> With reference to FIG. 15, a load changing means 100 which is a modified example of the load changing means will be described. The medium feeding device 10 is equipped with a roller holding section 101 that rotatably holds the separation roller 15 and has a swing shaft 102 that swings the held separation roller 15 toward and away from the feed roller 14, and a pressure spring 103 as a "pressing section" that presses the separation roller 15 toward the feed roller 14 via the roller holding section 101. The load changing means 100 is configured to change the pressing load K of the separation roller 15 against the feed roller 14 by moving the position of the swing shaft 102.

[0118] The oscillation shaft 102 is configured to be displaceable between a position α shown in the left diagram of FIG. 15 and a position β shown in the right diagram of FIG. When the position of the oscillation shaft 102 changes, the angle θ formed by the tangent line at the nip position N between the separation roller 15 and the feed roller 14 and the line segment connecting the center of the oscillation shaft 102 and the nip position N changes. The pressing force of the pressing spring 103 is resolved into arrows a, b, and c according to the angle θ. The smaller the angle θ, the larger the pressing load K (arrow c) on the feed roller 14 at the nip position N becomes.

[0119] When the oscillation shaft 102 is at position α shown in the left diagram of Fig. 15, the angle θ is θ1, and the pressure load K at this time is K1. Moreover, when the oscillation shaft 102 is at position β shown in the right diagram of Fig. 15, the angle θ is θ2, and the pressure load K at this time is K2. The angle θ is θ1<θ2, and therefore the pressure load K is K1>K2.

[0120] By the load changing means 100 as described above, the pressing load K of the separation roller 15 against the feed roller 14 can be changed between a pressing load K1 and a pressing load K2.

[0121] <<Modification example 3 of load change method>> With reference to FIG. 16, a load changing means 110 which is a modified example of the load changing means will be described. The medium feeding device 10 is equipped with a roller holding section 111 that rotatably holds the separation roller 15 and has a swing shaft 112 that swings the held separation roller 15 toward and away from the feed roller 14, and a pressure spring 113 as a "pressing section" that presses the separation roller 15 toward the feed roller 14 via the roller holding section 111. The load changing means 110 regulates the position of the separation roller 15 relative to the feed roller 14 against the pressing force of the pressing spring 113 by abutting against the roller holding portion 111, and is provided with a displacement member 115 that is displaceable in a direction that changes the position of the separation roller 15 relative to the feed roller 14.

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

[0123] When the displacement member 115 is displaced upward, that is, in a direction resisting the pressing force of the pressure spring 113, the pressing load K of the separation roller 15 against the feed roller 14 decreases. When the displacement member 115 displaced upward is returned to its downward position, the pressing load K increases. By using the load changing means 110 as described above, the pressing load K of the separation roller 15 against the feed roller 14 can be easily changed.

[0124] <<Modification example 4 of load change method>> With reference to FIG. 17, a load changing means 120 which is a modified example of the load changing means will be described. The medium feeding device 10 is provided with a power transmission mechanism 30A that transmits power from a first driving source 25 (not shown in FIG. 17, see FIG. 4) that drives the separation roller 15. The power transmission mechanism 30A includes a first gear 121 that is integrally formed on the rotating shaft 15a of the separation roller 15, a second gear 122 that is integrally formed on the rotating shaft 15a of the separation roller 15 and has a different reduction ratio than the first gear 121, and a switching gear 125 that is displaceable between a first position M1 (left diagram in Figure 17) that transmits the power of the first driving source 25 to the first gear 121 and a second position M2 (right diagram in Figure 17) that transmits the power of the first driving source 25 to the second gear 122. As an example, the reduction ratio R1 of the first gear 121 is set to be relatively low with respect to the reduction ratio R2 of the second gear 122 (R1 <R2)。 Incidentally, the power transmission mechanism from the first drive source 25 to the switching gear 125, which is omitted in FIG. 17, can be configured using a gear train made up of a plurality of gears, a belt mechanism, or the like. 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 FIG. 17) and a second position M2 (right diagram in FIG. 17).

[0125] When the power transmission mechanism 30A transmits power from the first drive source 25 to the separation roller 15 to rotate the separation roller 15 in the second rotation direction B, the higher the reduction ratio of the gear integrally provided on the rotation shaft 15a of the separation roller 15, the greater the lifting force (the force applied in the direction in which the separation roller 15 moves 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 of the separation roller 15 decreases. Therefore, the pressing load K2 in the state shown in the right diagram of Figure 17, in which the switching gear 125 is positioned at the second position M2 and power is transmitted to the rotating shaft 15a via the second gear 122 with the high reduction ratio R2, is smaller than the pressing load K1 in the state shown in the left diagram of Figure 17, in which the switching gear 125 is positioned at the first position M1 and power is transmitted to the rotating shaft 15a via the first gear 121 with the 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 a pressing load K1 and a pressing load K2.

[0127] When the control unit 19 switches the feed control (including the above-mentioned separation setting) for each paper type, the user may select the paper type, i.e., the feed control, via a UI (user interface) displayed on a display unit of the operation panel 7, or a hard switch for selecting the paper type may be provided on the front surface of the device where the operation panel 7 is provided. This hard switch may be located, for example, together with a power button. By providing such a hard switch, the user can directly select the paper type without opening a menu screen or the like. Furthermore, this hard switch may be set to function as a scan execution button in addition to selecting the paper type.

[0128] Specifically, for example, the four types of paper, "document," "normal photo," "panorama photo," and "instant photo," can be selected as the paper type. In this case, the above-mentioned hardware switch is provided for each paper type, and a total of four hardware switches (hard switches for selecting paper type) are provided on the front of the device. Note that instant photos are photos that are composed of multiple layers, such as Polaroid (a registered trademark of Polaroid Corporation) photos, and if separation is performed with the separation roller 15 in the separation state, the layers may separate and cause damage. Therefore, in the case of instant photos, it is preferable to set the above-mentioned separation switching means 27 (FIG. 5) as the feed control to the "non-separation state" in which no separation is performed, and in the case of other paper types, to the above-mentioned "separation state" as the feed control. By setting the separation according to the paper type in response to each hardware switch, appropriate separation can be performed. In addition, since the feeding control includes not only the separation setting but also double feed detection using the double feed detection unit 28 (FIG. 3) and jam detection, more appropriate transport can be achieved by switching these settings to the appropriate ones according to the paper type.

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

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

[0131] 1...scanner (image reading device), 2...device main body, 3...lower unit, 4...upper unit, 5...output tray, 6...feed port, 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...feed roller (feed section), 15...separation roller, 16...pair of transport rollers, 17...pair of ejection rollers, 18...ejection port, 19...control section , 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 driving source, 26...second driving source, 27...separation switching means, 28...multiple 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 change means, 41...torque limiter, 42...first The 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 portion, 62...pressure spring, 63...roller holding portion, 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 portion), 92...second coil spring (second pressing portion), 100...load changing means, 101...roller holding portion, 102...oscillating shaft, 103...pressing spring (pressing portion), 110...load changing means, 111...roller holding portion, 113...pressing spring (pressing portion), 115...displacement member, 120...load changing means, 121...first gear, 122...second gear, 125...switching gear, P...paper (medium)

Claims

1. A first driving source; A second drive source; A reading unit that reads the medium; a medium placement section for placing a medium; a feeding roller that is driven by the second driving source and feeds the medium from the medium placement unit; And, a roller that nips the medium between itself and the feed roller to separate the medium. The medium is rotated in a second direction by the first driving source in a direction opposite to the first direction of rotation for feeding the medium downstream. A separation roller to which a driving torque is applied; The rotational torque applied to the separation roller in the first rotational direction is a predetermined torque upper limit value When the torque exceeds a limit torque, the separation roller is rotated idly in the first rotation direction. a first torque limiter; The rotational torque applied to the separation roller in the first rotational direction is a predetermined torque upper limit value When the torque exceeds a limit torque, the separation roller is rotated idly in the first rotation direction. a second torque limiter; a torque changing means for changing the limit torque of the separation roller; a speed change means for changing a rotation speed of the first drive source; a control unit that controls the first drive source and the second drive source, The torque changing means is The first torque limiter and the second torque limiter are moved to a first position and a second position. The limiter has an engagement portion that can be engaged with at least one of the limiters, A first rotational torque is applied at the first position, and the first rotational torque is applied at the second position. A second rotational torque larger than the first torque is applied. a load changing means for changing a pressing load of the separation roller against the feeding roller, The control unit changes a separation setting including the pressure load according to a condition during feeding. Possibly configured, a power transmission mechanism that transmits power from the first drive source, The power transmission mechanism includes a first gear that is integrally provided on a rotation shaft of the separation roller; a second gear that is integrally provided on a rotation shaft of the separation roller and has a reduction ratio different from that of the first gear; a first position at which the power of the first driving source is transmitted to the first gear; a shift gear displaceable to a second position for transmitting a shift signal to the second gear; The load changing means switches the switching gear between the first position and the second position. and changing the pressing load by changing the pressing load.

2. A first driving source; A second drive source; A reading unit that reads the medium; a medium placement section for placing a medium; a feeding roller that is driven by the second driving source and feeds the medium from the medium placement unit; And, a roller that nips the medium between itself and the feed roller to separate the medium. The medium is rotated in a second direction by the first driving source in a direction opposite to the first direction of rotation for feeding the medium downstream. A separation roller to which a driving torque is applied; The rotational torque applied to the separation roller in the first rotational direction is a predetermined torque upper limit value When the torque exceeds a limit torque, the separation roller is rotated idly in the first rotation direction. a first torque limiter; The rotational torque applied to the separation roller in the first rotational direction is a predetermined torque upper limit value When the torque exceeds a limit torque, the separation roller is rotated idly in the first rotation direction. a second torque limiter; a torque changing means for changing the limit torque of the separation roller; a load changing unit that changes a pressing load of the separation roller against the feed roller; a control unit that controls the first drive source and the second drive source, The torque changing means is The first torque limiter and the second torque limiter are moved to a first position and a second position. The limiter has an engagement portion that can be engaged with at least one of the limiters, A first rotational torque is applied at the first position, and the first rotational torque is applied at the second position. A second rotational torque larger than the first torque is applied, a power transmission mechanism that transmits power from the first drive source, The power transmission mechanism includes a first gear that is integrally provided on a rotation shaft of the separation roller; a second gear that is integrally provided on a rotation shaft of the separation roller and has a reduction ratio different from that of the first gear; a first position at which the power of the first driving source is transmitted to the first gear; a shift gear displaceable to a second position for transmitting a shift signal to the second gear; The load changing means switches the switching gear between the first position and the second position. and changing the pressing load by changing the pressing load.

3. 2. The image reading apparatus according to claim 1, wherein the second medium is relatively thinner than the first medium. When separating the bodies, at least one of the pressing load, the rotation speed, and the limit torque is In the image reading device, the above-mentioned first medium is prevented from being separated from the other medium. Place.

4. 2. The image reading apparatus according to claim 1, wherein the second medium has a relatively higher frictional force than the first medium. When separating the medium, at least one of the pressing load, the rotation speed, and the limit torque is and increasing either one of the first medium and the second medium in comparison with a case where the first medium is separated. Place.

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