Medium conveying device

Abstract

To provide a medium conveying device capable of continuously pressing a separation roller toward a feed roller side with an appropriate force while reducing power consumption.SOLUTION: A medium conveying device has: a feed roller which feeds a medium; a separation roller disposed facing the feed roller; a motor which generates a driving force by supplying electric power; a cam member which presses the separation roller toward the feed roller side by being rotated in a first direction in accordance with the driving force; and a driving force transmission part which is provided between the motor and the cam member, transmits the driving force from the motor to the cam member, and is provided so that the cam member continues pressing the separation roller toward the feed roller side without rotating the cam member in a second direction opposite to the first direction even if the supply of electric power to the motor is interrupted.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a medium transport device, and more particularly to a medium transport device that feeds a medium using a feed roller and a separation roller. [Background technology]

[0002] Media conveying devices, such as scanners that capture images while conveying media, have the function of separating multiple media using a feed roller and a separation roller. In such media conveying devices, the separation roller must be appropriately pressed against the feed roller to properly separate the media. The force pressing the separation roller against the feed roller varies depending on component variations and the wear state of the roller, and therefore must be adjusted for each device. Conventionally, media conveying devices have used a driving force generated by a motor to adjust the force pressing the separation roller against the feed roller, and controlled the motor to continue pressing the separation roller against the feed roller with the adjusted force.

[0003] A paper feeder has been disclosed that has a paper separation mechanism consisting of a separation roller and a retard roller with a torque limiter, and can change the pressure between the two by biasing the retard roller in a direction toward or away from the separation roller (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-95372 Summary of the Invention [Problem to be solved by the invention]

[0005] In a medium transport device, it is desirable to continuously press the separation roller against the feed roller with an appropriate force while reducing power consumption.

[0006] An object of the present invention is to provide a medium transport device that can continuously press a separation roller against a feed roller with an appropriate force while reducing power consumption. [Means for solving the problem]

[0007] A media conveying device according to one aspect of the present invention comprises a feed roller for feeding a medium, a separation roller arranged opposite the feed roller, a motor that generates a driving force when supplied with power, a cam member that rotates in a first direction in accordance with the driving force to press the separation roller toward the feed roller, and a driving force transmission unit that is provided between the motor and the cam member, transmits the driving force from the motor to the cam member, and is configured so that even if the supply of power to the motor is cut off, the cam member does not rotate in a second direction opposite to the first direction, and the cam member continues to press the separation roller toward the feed roller. [Effects of the Invention]

[0008] According to the present invention, the medium transport device can continue to press the separation roller against the feed roller with an appropriate force while reducing power consumption. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing a medium conveying device 100. [Figure 2] 2 is a diagram for explaining a transport path inside the medium transport device 100. FIG. [Figure 3] FIG. 10 is a schematic diagram for explaining a driving force transmission mechanism 130 and the like. [Figure 4] 10 is a schematic diagram for explaining a worm 132 and the like. FIG. [Figure 5] FIG. 2 is a perspective view of a pressure applying mechanism 140. [Figure 6] FIG. 2 is a side view of the pressure applying mechanism 140. [Figure 7] FIG. 2 is a perspective view showing the pressure applying mechanism 140 in a state where it is removed from the inner housing 120. [Figure 8] 10 is a schematic diagram of a driving force transmission mechanism 130 and a pressure applying mechanism 140 as viewed from the upstream side. FIG. [Figure 9] 1 is a block diagram showing a schematic configuration of a medium conveying device 100. FIG. [Figure 10] FIG. 2 is a diagram showing a schematic configuration of a storage device 160 and a processing circuit 170. [Figure 11] 10 is a flowchart illustrating an example of the operation of a setting process. [Figure 12] 10 is a flowchart illustrating an example of the operation of a medium reading process. [Figure 13] 10 is a schematic diagram for explaining another driving force transmission mechanism 230. FIG. [Figure 14] 10 is a schematic diagram for explaining another driving force transmission mechanism 330. FIG. [Figure 15] 10 is a schematic diagram for explaining another driving force transmission mechanism 430 and the like. [Figure 16] 10A and 10B are schematic diagrams for explaining the ratchet gear 432. FIG. [Figure 17] 10 is a schematic diagram for explaining a pressure applying mechanism 440. FIG. [Figure 18] 10 is a schematic diagram for explaining a pressure applying mechanism 440. FIG. [Figure 19] 10A and 10B are schematic diagrams for explaining another driving force transmission mechanism 530 and the like. [Figure 20] FIG. 10 is a diagram showing a schematic configuration of a processing circuit 670 according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] A medium transport device according to one aspect of the present invention will be described below with reference to the drawings. However, please note that the technical scope of the present invention is not limited to the embodiments described therein, but extends to the inventions set forth in the claims and their equivalents.

[0011] FIG. 1 is a perspective view showing a medium conveying device 100 configured as an image scanner. The medium conveying device 100 conveys a medium, which is an original document, and captures an image. The medium may be paper, thin paper, thick paper, card, or the like. The medium conveying device 100 may also be a facsimile, a copier, a multifunction printer (MFP, Multifunction Peripheral), or the like. Note that the medium being conveyed may not be an original document, but may be a print target or the like, and the medium conveying device 100 may also be a printer or the like.

[0012] The medium conveying device 100 includes a first housing 101, a second housing 102, a loading table 103, an ejection table 104, an operation device 105, a display device 106, and the like.

[0013] The first housing 101 is disposed above the medium conveying device 100 and is engaged with the second housing 102 by a hinge so that it can be opened and closed when a medium is jammed or when the inside of the medium conveying device 100 is to be cleaned.

[0014] The loading platform 103 engages with the second housing 102 so that the transported media can be placed thereon. The loading platform 103 is provided on the side of the second housing 102 on the media supply side so that it can move in a substantially vertical direction (height direction) A1 by a motor (not shown). The ejection platform 104 is formed on the first housing 101 so that it can hold the ejected media, and it stacks the ejected media.

[0015] The operation device 105 has input devices such as buttons and an interface circuit for acquiring signals from the input devices, accepts input operations by a user, and outputs operation signals in response to the user's input operations. The display device 106 has a display such as a liquid crystal display, an organic EL (Electro-Luminescence) display, or the like, and an interface circuit for outputting image data to the display, and displays the image data on the display.

[0016] 1, arrow A2 indicates the medium transport direction, arrow A3 indicates the medium discharge direction, and arrow A4 indicates the width direction perpendicular to the medium transport direction. In the following, "upstream" refers to the upstream side of the medium transport direction A2 or the medium discharge direction A3, and "downstream" refers to the downstream side of the medium transport direction A2 or the medium discharge direction A3.

[0017] FIG. 2 is a diagram for explaining the transport path inside the medium transport device 100. As shown in FIG.

[0018] The transport path inside the media transport device 100 includes a first media sensor 111, a pick roller 112, a feed roller 113, a separation roller 114, a second media sensor 115, a third media sensor 116, first to eighth transport rollers 117a-h, first to eighth driven rollers 118a-h, and an imaging device 119.

[0019] The number of each of the pick roller 112, the feed roller 113, the separation roller 114, the first to eighth conveying rollers 117a-h, and / or the first to eighth driven rollers 118a-h is not limited to one, and may be more than one. In this case, the multiple pick rollers 112, the feed roller 113, the separation roller 114, the first to eighth conveying rollers 117a-h, and / or the first to eighth driven rollers 118a-h are arranged at intervals in the width direction A4.

[0020] The surface of first housing 101 facing second housing 102 forms first guide 101a of the medium transport path, and the surface of second housing 102 facing first housing 101 forms second guide 102a of the medium transport path.

[0021] The first medium sensor 111 is disposed on the mounting table 103, i.e., upstream of the feed roller 113 and separation roller 114, and detects the state of the medium on the mounting table 103. The first medium sensor 111 determines whether or not a medium is placed on the mounting table 103 by using a contact detection sensor that passes a predetermined current when the medium is in contact with the mounting table 103 or when the medium is not in contact with the mounting table 103. The first medium sensor 111 generates and outputs a first medium signal whose signal value changes depending on whether or not a medium is placed on the mounting table 103. Note that the first medium sensor 111 is not limited to a contact detection sensor, and any other sensor capable of detecting the presence or absence of a medium, such as an optical detection sensor, may be used as the first medium sensor 111.

[0022] Pick roller 112 is provided in first housing 101, and comes into contact with a medium placed on mounting table 103 raised to approximately the same height as the medium transport path, and feeds the medium downstream.

[0023] The feed roller 113 is provided in the first housing 101 downstream of the pick roller 112, and feeds the media placed on the mounting table 103 and fed by the pick roller 112 further downstream. The separation roller 114 is a so-called brake roller or retard roller, and is provided in the second housing 102 facing the feed roller 113. The feed roller 113 and the separation roller 114 perform a media separation operation, separating the media and feeding them one by one. The feed roller 113 is provided above the separation roller 114, and the medium conveying device 100 feeds the media by a so-called top-down method. The feed roller 113 may also be provided below the separation roller 114, and feed the media by a so-called bottom-up method.

[0024] The second media sensor 115 is disposed downstream of the feed roller 113 and the separation roller 114 and upstream of the first transport roller 117a and the first driven roller 118a, i.e., upstream of the imaging device 119, and detects media transported to that position. The second media sensor 115 may be disposed anywhere in the transport path as long as it is downstream of the feed roller 113 and the separation roller 114. The second media sensor 115 includes a light emitter and a light receiver provided on one side of the media transport path (e.g., the second housing 102 side), and a light guide tube provided at a position facing the light emitter and light receiver across the media transport path (e.g., the first housing 101 side). The light emitter is an LED (Light Emitting Diode) or the like, and emits light toward the media transport path. On the other hand, the light receiver is a photodiode or the like, and receives light emitted by the light emitter and guided by the light guide tube. When a medium is present in a position opposite second medium sensor 115, the light emitted from the light emitter is blocked by the medium, and the light receiver does not receive the light emitted from the light emitter. Based on the intensity of the received light, the light receiver generates and outputs a second medium signal whose signal value changes depending on whether a medium is present or not at the position of second medium sensor 115.

[0025] The third media sensor 116 is disposed downstream of the second media sensor 115 and upstream of the first transport roller 117a and the first driven roller 118a, i.e., upstream of the image capture device 119, and detects media transported to that position. The third media sensor 116 may be disposed anywhere within the transport path as long as it is downstream of the second media sensor 115. The third media sensor 116 includes a light emitter and a light receiver disposed on one side of the media transport path (e.g., the second housing 102 side), and a light guide tube disposed opposite the light emitter and light receiver across the media transport path (e.g., the first housing 101 side). The light emitter is an LED or the like, and emits light toward the media transport path. Meanwhile, the light receiver is a photodiode or the like, and receives light emitted by the light emitter and guided by the light guide tube. When a medium is present in a position opposite third medium sensor 116, the light emitted from the light emitter is blocked by the medium, and the light receiver does not receive the light emitted from the light emitter. Based on the intensity of the received light, the light receiver generates and outputs a third medium signal whose signal value changes depending on whether a medium is present or not at the position of third medium sensor 116.

[0026] Note that a reflective member such as a mirror may be used instead of a light guide tube in second medium sensor 115 and / or third medium sensor 116. Also, in second medium sensor 115 and / or third medium sensor 116, the light emitter and light receiver may be disposed opposite each other across the medium transport path. Also, second medium sensor 115 and / or third medium sensor 116 may detect the presence of a medium using a contact detection sensor or the like that passes a predetermined current when the medium is in contact or when the medium is not in contact.

[0027] The first to eighth transport rollers 117a-h and the first to eighth driven rollers 118a-h are provided downstream of the feed roller 113 and the separation roller 114, and transport the medium fed by the feed roller 113 and the separation roller 114 downstream.

[0028] The imaging device 119 includes a first imaging device 119a and a second imaging device 119b arranged opposite each other across the medium transport path. The first imaging device 119a has a line sensor based on a CIS (Contact Image Sensor) of a 1:1 optical system type having CMOS (Complementary Metal Oxide Semiconductor) imaging elements linearly arranged in the main scanning direction. The first imaging device 119a also has a lens that forms an image on the imaging element and an A / D converter that amplifies and analog-to-digital (A / D) converts the electrical signal output from the imaging element. The first imaging device 119a captures an image of the surface of the medium being transported, generates an input image, and outputs it.

[0029] Similarly, the second imaging device 119b has a CIS line sensor with a 1x magnification optical system having CMOS imaging elements arranged linearly in the main scanning direction. The second imaging device 119b also has a lens that forms an image on the imaging element and an A / D converter that amplifies and A / D converts the electrical signal output from the imaging element. The second imaging device 119b captures an image of the back side of the medium being conveyed, generates an input image, and outputs it.

[0030] The medium conveying device 100 may be provided with only one of the first and second imaging devices 119a and 119b, and may read only one side of the medium. Also, instead of a CIS line sensor with an equal-magnification optical system and a CMOS imaging element, a CIS line sensor with an equal-magnification optical system and a CCD (Charge Coupled Device) imaging element may be used. Also, a reduction optical system type line sensor with a CMOS or CCD imaging element may be used.

[0031] The medium placed on the mounting table 103 is transported between the first guide 101a and the second guide 102a in the medium transport direction A2 by the rotation of the pick roller 112 and the feed roller 113 in the medium feed directions A5 and A6, respectively. Meanwhile, when multiple media are placed on the mounting table 103, the separation roller 114 rotates in the direction A7 opposite to the medium feed direction, so that only the media in contact with the feed roller 113 are separated from the media placed on the mounting table 103.

[0032] The medium is guided by the first guide 101a and the second guide 102a and fed to the imaging position of the imaging device 119 by the rotation of the first and second conveyance rollers 117a and 117b in the directions of arrows A8 and A9, and is imaged by the imaging device 119. Furthermore, the medium is discharged onto the discharge tray 104 by the rotation of the third to eighth conveyance rollers 117c to 117h in the directions of arrows A10 to A15, respectively.

[0033] 3 is a schematic diagram for explaining the driving force transmission mechanism 130 and the pressure applying mechanism 140. FIG. 3 is a schematic diagram of the periphery of the separation roller 114 as viewed from the upstream side.

[0034] As shown in FIG. 3, the medium conveying device 100 further includes an inner housing 120, a first motor 121, a driving force transmission mechanism 130, and a pressure applying mechanism 140.

[0035] The inner housing 120 is disposed below the separation roller 114 and is fixed within the second housing 102 .

[0036] The first motor 121 is an example of a motor, and when power is supplied to it in accordance with control from a processing circuit described later, it rotates the rotating shaft 121a and generates a driving force to press the separation roller 114 toward the feed roller 113.

[0037] The driving force transmission mechanism 130 is an example of a driving force transmission unit, and is provided between the first motor 121 and the cam member 141 of the pressure applying mechanism 140, and transmits the driving force generated by the first motor 121 to the cam member 141. The driving force transmission mechanism 130 includes a belt 131, a worm 132, a worm wheel 133, a cam member shaft 134, etc.

[0038] The belt 131 is suspended between the rotation shaft 121a of the first motor 121 and a worm shaft 132a, which is the rotation shaft of the worm 132. The worm 132 and the worm wheel 133 form a worm gear. The worm 132 is provided so as to rotate in conjunction with the rotation of the first motor 121 via the belt 131. The worm wheel 133 is provided so as to mesh with the worm 132, and is attached to a cam member shaft 134. The cam member shaft 134 is the rotation shaft of the cam member 141. The cam member shaft 134 is a rod-shaped member extending in the width direction A4, and is supported by the inner housing 120 so as to rotate in conjunction with the rotation of the worm wheel 133.

[0039] FIG. 4 is a schematic diagram for explaining the worm 132 and the worm wheel 133. As shown in FIG.

[0040] As shown in FIG. 4, the worm 132 is a cylindrical worm, and a screw-like gear is formed on the side surface of the worm 132. The worm wheel 133 has helical teeth that mesh with the screw-like gear formed on the side surface of the worm 132. As a result, the worm wheel 133 rotates in conjunction with the rotation of the worm 132. On the other hand, the lead angle of the groove of the worm 132 is set to a value that prevents rotation from being transmitted from the worm wheel 133 side to the worm 132 side. Therefore, the worm 132 does not rotate in conjunction with the rotation from the worm wheel 133 side.

[0041] Fig. 5 is a perspective view of the pressure applying mechanism 140 of Fig. 3 taken along the line A-A' and seen from the side. Fig. 6 is a side view of the pressure applying mechanism 140 of Fig. 3 taken along the line A-A' and seen from the side. In addition to the separation roller 114, Fig. 6 also shows the pick roller 112, the feed roller 113, the first and second conveyor rollers 117a-b, and the first and second driven rollers 118a-b. Fig. 7 is a perspective view of the pressure applying mechanism 140 removed from the inner housing 120.

[0042] 3 and 5 to 7, the pressure applying mechanism 140 is a mechanism for pressing the separation roller 114 toward the feed roller 113 in accordance with the driving force generated by the first motor 121 and transmitted by the driving force transmission mechanism 130. The pressure applying mechanism 140 has a cam member 141, a support member 142, a first elastic member 143, a second elastic member 144, a cam member sensor 145, and the like.

[0043] The cam member 141 is attached to the cam member shaft 134 so as to rotate (swing) in accordance with the rotation of the cam member shaft 134. The cam member 141 has an engaging portion 141a and a detected portion 141b. The engaging portion 141a is a recess for attaching the first elastic member 143. The detected portion 141b is a plate-like member that rotates (swings) in conjunction with the rotation (swing) of the cam member 141.

[0044] The support member 142 is an example of a support portion, is swingably supported by the inner housing 120, and supports the separation roller 114. The support member 142 has a first plate-shaped member 142a, a second plate-shaped member 142b, a support member shaft 142c, a first engaging member 142d, and a second engaging member 142e.

[0045] The first plate-shaped member 142a and the second plate-shaped member 142b are arranged side by side at an interval in the width direction A4 so as to extend in a direction perpendicular to the width direction A4. A separation roller shaft 114a, which is the rotation shaft of the separation roller 114, is attached to the upstream and upper ends of each of the first plate-shaped member 142a and the second plate-shaped member 142b. In addition, the ends in the width direction A4 of the support member shaft 142c, the first engagement member 142d, and the second engagement member 142e are attached to the inner surfaces of the first plate-shaped member 142a and the second plate-shaped member 142b.

[0046] The support member shaft 142c is a swing axis of the support member 142 and is a rod-shaped member extending in the width direction A4. The support member shaft 142c is rotatably supported by the inner casing 120, and both ends of the support member shaft 142c in the width direction A4 are attached to the inner surfaces of the first plate-shaped member 142a and the second plate-shaped member 142b. As a result, the separation roller shaft 114a and the separation roller 114 attached to the first plate-shaped member 142a and the second plate-shaped member 142b are supported so as to be swingable relative to the inner casing 120 in accordance with the rotation of the support member shaft 142c.

[0047] The first engaging member 142d is a rod-shaped member extending in the width direction A4, and both ends of the first engaging member 142d in the width direction A4 are attached to the inner surfaces of the first plate-shaped member 142a and the second plate-shaped member 142b.

[0048] The second engaging member 142e is a rod-shaped member extending in the width direction A4, and both ends of the second engaging member 142e in the width direction A4 are attached to the inner surfaces of the first plate-shaped member 142a and the second plate-shaped member 142b.

[0049] The first elastic member 143 is a tension coil spring or the like, and one end of the first elastic member 143 is attached to the engagement portion 141a of the cam member 141, and the other end of the first elastic member 143 is attached to the first engagement member 142d of the support member 142. The first elastic member 143 is pulled in accordance with the rotation of the cam member shaft 134 and the cam member 141, and applies a force to the first engagement member 142d toward the upstream side. Note that the first elastic member 143 may be any member that applies a force to the first engagement member 142d toward the upstream side in response to the rotation of the cam member 141, and may be a spring other than a tension coil spring, such as a compression coil spring or a leaf spring. The first elastic member 143 may also be an elastic member other than a spring, such as rubber.

[0050] The second elastic member 144 is a torsion coil spring or the like, and is attached to the support member shaft 142c. One end of the second elastic member 144 is fixed to the inner housing 120, and the other end of the second elastic member 144 is attached to the second engagement member 142e of the support member 142, and the second elastic member 144 applies an upward force to the second engagement member 142e. The second elastic member 144 may be any member that applies an upward force to the second engagement member 142e, and may be a spring other than a torsion coil spring, such as a compression coil spring or a leaf spring. The second elastic member 144 may also be an elastic member other than a spring, such as rubber.

[0051] The cam member sensor 145 has a light emitter 145a and a light receiver 145b. The light emitter 145a and the light receiver 145b face each other and are provided so that the detected portion 141b of the cam member 141 can enter between them. The light emitter 145a is an LED or the like and emits light toward the light receiver 145b. On the other hand, the light receiver 145b is a photodiode or the like and receives the light emitted by the light emitter 145a. When the detected portion 141b is present between the light emitter 145a and the light receiver 145b, the light emitted from the light emitter 145a is blocked by the detected portion 141b, and therefore the light receiver 145b does not receive the light emitted from the light emitter 145a. Based on the intensity of the received light, the light receiver 145b generates and outputs a cam member signal whose signal value changes depending on whether the detection target 141b is present or not between the light emitter 145a and the light receiver 145b.

[0052] The operations of the pressure applying mechanism 140 and the driving force transmission mechanism 130 will be described below.

[0053] FIG. 8 is a schematic diagram of the driving force transmission mechanism 130 and the pressure applying mechanism 140 as viewed from the upstream side.

[0054] 8, when power is supplied to the first motor 121 and the first motor 121 rotates in the direction of arrow A21, the worm 132 rotates in the direction of arrow A21 via the belt 131 and the worm shaft 132a. As the worm 132 rotates, the worm wheel 133 rotates in the direction of arrow A22, and the cam member 141 rotates (oscillates) in the direction of arrow A22 via the cam member shaft 134.

[0055] 5, when the cam member 141 rotates (swings) in the direction of arrow A22, the first elastic member 143 is pulled in the direction of arrow A23 (upstream), and a force in the direction of arrow A23 is applied to the first engagement member 142d by the first elastic member 143. By applying a force in the direction of arrow A23 to the first engagement member 142d, the separation roller 114 attached to the upper end on the upstream side of the support member 142 is pressed in the direction of arrow A24, and is pressed toward the feed roller 113.

[0056] In this way, the cam member 141 rotates in the direction of the arrow A22 according to the driving force generated by the first motor 121, and presses the separation roller 114 toward the feed roller 113. The direction of the arrow A22 is an example of the first direction.

[0057] Furthermore, a force in the direction of arrow A25 (upward) is applied to the second engaging member 142e by the second elastic member 144. By applying a force in the direction of arrow A25 to the second engaging member 142e, the separation roller 114 attached to the upstream upper end of the support member 142 is pressed in the direction of arrow A24, and is pressed toward the feed roller 113.

[0058] 8, when the first motor 121 rotates in the opposite direction of the arrow A21, the worm 132 rotates in the opposite direction of the arrow A21 via the belt 131 and the worm shaft 132a. As the worm 132 rotates, the worm wheel 133 rotates in the opposite direction of the arrow A22, and the cam member 141 swings in the opposite direction of the arrow A22 via the cam member shaft 134.

[0059] 5, when the cam member 141 swings in the direction opposite to the arrow A22, the force applied to the first engagement member 142d in the direction of the arrow A23 by the first elastic member 143 is reduced. The reduction in the force applied to the first engagement member 142d in the direction of the arrow A23 reduces the force that presses the feed roller 113 on the separation roller 114 attached to the upstream upper end of the support member 142.

[0060] In this way, the cam member 141 rotates in the direction of arrow A22 or the direction opposite to arrow A22 in accordance with the driving force generated by the first motor 121, thereby adjusting the force that presses the separation roller 114 toward the feed roller 113. The direction opposite to arrow A22 is an example of a second direction opposite to the first direction.

[0061] 5, the cam member 141 pulls the first elastic member 143 in the direction of arrow A23, and conversely, a force in the opposite direction of arrow A23 is applied to the cam member 141 and the cam member shaft 134 by the first engagement member 142d. However, as described above, the rotation from the worm wheel 133 side is not transmitted to the worm 132 side. Therefore, even if the supply of power to the first motor 121 is cut off, the cam member 141 and the cam member shaft 134 do not rotate in the opposite direction of arrow A22, and the cam member 141 continues to press the separation roller 114 toward the feed roller 113.

[0062] In this way, the worm 132 and the worm wheel 133 are arranged so that even if the supply of power to the first motor 121 is cut off, the cam member 141 does not rotate in the opposite direction of the arrow A22, and the cam member 141 continues to press the separation roller 114 toward the feed roller 113. Therefore, after controlling the first motor 121 to set the separation roller 114, the medium conveying device 100 can cut off the supply of power to the first motor 121, thereby reducing power consumption.

[0063] FIG. 9 is a block diagram showing a schematic configuration of the medium conveying device 100. As shown in FIG.

[0064] In addition to the above-described configuration, the medium conveying device 100 further includes a second motor 151, an interface device 152, a storage device 160, a processing circuit 170, and the like.

[0065] The second motor 151 includes one or more motors, and rotates the pick roller 112, the feed roller 113, the separation roller 114, and the first to eighth transport rollers 117a-h to feed and transport the medium in response to a control signal from the processing circuit 170. The first to eighth driven rollers 118a-h may be configured to rotate by the driving force from the second motor 151, rather than being driven to rotate in accordance with the rotation of the first to eighth transport rollers 117a-h. The second motor 151 also moves the mounting table 103 in response to a control signal from the processing circuit 170.

[0066] The interface device 152 has an interface circuit conforming to a serial bus such as USB, and is electrically connected to an information processing device (not shown) (for example, a personal computer, a personal digital assistant, etc.) to transmit and receive scanned images and various information. Instead of the interface device 152, a communication unit having an antenna for transmitting and receiving wireless signals and a wireless communication interface circuit for transmitting and receiving signals via a wireless communication line in accordance with a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network).

[0067] The storage device 160 includes a memory device such as a RAM (Random Access Memory) or a ROM (Read Only Memory), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk or optical disk. The storage device 160 also stores computer programs, databases, tables, and the like used for various processes of the medium conveying device 100. The computer programs may be installed into the storage device 160 from a computer-readable portable recording medium using a known setup program or the like. The portable recording medium is, for example, a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or the like.

[0068] The processing circuit 170 operates based on a program stored in advance in the storage device 160. The processing circuit 170 is, for example, a CPU (Central Processing Unit). The processing circuit 170 may be a DSP (Digital Signal Processor), an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like.

[0069] The processing circuit 170 is connected to the operation device 105, the display device 106, the first medium sensor 111, the second medium sensor 115, the third medium sensor 116, the imaging device 119, the cam member sensor 145, the first motor 121, the second motor 151, the interface device 152, the storage device 160, etc., and controls each of these components. The processing circuit 170 controls the second motor 151 to transport the medium, controls the imaging device 119 to acquire an input image, and transmits the acquired input image to the information processing device via the interface device 152. The processing circuit 170 also controls the first motor 121 to press the separation roller 114 toward the feed roller 113.

[0070] FIG. 10 is a diagram showing a schematic configuration of the storage device 160 and the processing circuit 170. As shown in FIG.

[0071] 10, the storage device 160 stores various programs, such as a measurement program 161, a setting program 162, and a control program 163. Each of these programs is a functional module implemented by software running on a processor. The processing circuitry 170 reads each of the programs stored in the storage device 160 and operates in accordance with the read programs, thereby functioning as a measurement unit 171, a setting unit 172, and a control unit 173.

[0072] FIG. 11 is a flowchart showing an example of the operation of the setting process.

[0073] An example of the operation of the setting process of the medium conveying device 100 will be described below with reference to the flowchart shown in Fig. 11. The flow of the operation described below is executed mainly by the processing circuit 170 in cooperation with each element of the medium conveying device 100 based on a program previously stored in the storage device 160. The setting process is performed by an operator at a factory or the like before shipping the device. When the setting process is performed, the first housing 101 is opened, and a measuring device that measures the pressing force of the separation roller 114 is placed in a position facing the separation roller 114 instead of the feed roller 113.

[0074] First, the measurement unit 171 waits until it receives an instruction from an operator to adjust the cam member 141 (step S101). The instruction to adjust the cam member 141 is input using the operation device 105 or an information processing device, and the measurement unit 171 receives the instruction to adjust the cam member 141 when it receives an adjustment signal instructing the adjustment of the cam member 141 from the operation device 105 or the interface device 152.

[0075] When the instruction to adjust the cam member 141 is received, the measuring unit 171 drives the first motor 121 to rotate the cam member 141 (step S102).

[0076] First, measurement unit 171 places cam member 141 in a non-opposing position where detected portion 141b does not face cam member sensor 145. Measurement unit 171 rotates cam member 141 by a predetermined amount at regular intervals in the direction opposite to arrow A22 in FIG. 5 (the direction in which separation roller 114 moves downward), and receives a cam member signal from cam member sensor 145. Measurement unit 171 determines that cam member 141 is placed in the non-opposing position when the signal value of the received cam member signal indicates that detected portion 141b is not present between light emitter 145a and light receiver 145b.

[0077] Next, measurement unit 171 rotates cam member 141 by a predetermined amount in the direction of arrow A22 in FIG. 5 (the direction in which separation roller 114 moves upward) at regular intervals, and receives a cam member signal from cam member sensor 145. Measurement unit 171 determines that cam member 141 is positioned at the reference position when the signal value of the cam member signal changes from a value indicating that detection target portion 141b is not present between light emitter 145a and light receiver 145b to a value indicating that detection target portion 141b is present between light emitter 145a and light receiver 145b. Measurement unit 171 continues to measure the drive amount of first motor 121 that has been driven since cam member 141 was positioned at the reference position.

[0078] Next, the measurement unit 171 waits until it receives the setting of the initial position of the cam member 141 from the operator (step S103). The setting of the initial position of the cam member 141 is input using the operation device 105 or an information processing device. The measurement unit 171 receives the setting of the initial position of the cam member 141 when it receives a setting signal for setting the initial position of the cam member 141 from the operation device 105 or the interface device 152. The operator monitors a measuring device placed in a position opposite the separation roller 114, and when the pressing force of the separation roller 114 reaches a magnitude that satisfies the specifications of the device, it sets the current position of the cam member 141 as the initial position.

[0079] When the setting of the initial position of cam member 141 is accepted, measurement unit 171 stops first motor 121 to stop the rotation of cam member 141, and measures the amount of rotation of cam member 141 (step S104). Measurement unit 171 measures the amount of drive of first motor 121 after cam member 141 is placed at the reference position as the amount of rotation of cam member 141 from the reference position.

[0080] Next, the setting unit 172 sets a value based on the amount of rotation measured by the measurement unit 171 when the setting of the initial position of the cam member 141 by the operator as an initial setting value in the storage device 160 (step S105), and returns the process to step S101. For example, the setting unit 172 sets the amount of rotation measured in step S104 itself as the initial setting value. Note that the setting unit 172 may set the physical position, angle, etc. of the cam member 141 corresponding to the amount of rotation measured in step S104 as the initial setting value.

[0081] In multiple medium conveying devices 100, even if the drive amount of the first motor 121 is the same, the pressing force with which the separation roller 114 presses the feed roller 113 may differ due to variations in the characteristics of the elastic member, variations in the initial placement position of the cam member 141, etc. The medium conveying device 100 sets a value based on the amount of rotation of the cam member 141 from the reference position as the initial setting value. This makes it possible for each medium conveying device 100 to position the separation roller 114 at a position where the pressing force is the same, regardless of variations in the characteristics of the elastic member, variations in the initial placement position of the cam member 141, etc.

[0082] Note that measurement unit 171 may measure the amount of rotation of cam member 141 using a different type of sensor than cam member sensor 145. For example, measurement unit 171 may determine whether cam member sensor 145 is located at the reference position using a contact detection sensor that passes a predetermined current when cam member 141 is in contact or not in contact. Furthermore, detection target portion 141b may be formed with a large number of slits (light-transmitting holes). In this case, measurement unit 171 can measure the amount of rotation of cam member 141 from the reference position based on the number of times a state in which a slit exists between light emitter 145a and light receiver 145b and a state in which no slit exists and light is blocked by detection target portion 141b are detected.

[0083] As described above, in multiple medium conveying devices 100, the pressing force of the separation roller 114 may change due to variations in the characteristics of the elastic member and variations in the position of the cam member 141. In particular, variations in the position of the cam member 141 have a large effect on the pressing force of the separation roller 114, and even a slight change in the position of the cam member 141 can cause a large change in the pressing force of the separation roller 114.

[0084] The medium conveying device 100 applies force to the support member 142, which supports the separation roller 114, using two elastic members: a first elastic member 143 having one end fixed to the cam member 141, and a second elastic member 144 having one end fixed to the inner housing 120. The second elastic member 144 applies a constant force to the support member 142 regardless of the drive amount of the first motor 121, and the first elastic member 143 applies a force to the support member 142 according to the drive amount of the first motor 121. By using a spring as the second elastic member 144 whose spring constant is sufficiently larger than the spring constant of the first elastic member 143, the medium conveying device 100 can generate most of the force applied to the support member 142 by the second elastic member 144. In this case, the proportion of the force applied by the first elastic member 143 to the support member 142 is small, and the effect of variations in the position of the cam member 141 on the pressing force of the separation roller 114 is reduced. Therefore, by using the second elastic member 144 and the first elastic member 143, the medium conveying device 100 can reduce fluctuations in the pressing force of the separation roller 114 due to variations in the amount of movement of the cam member 141, thereby enabling stable separation of the medium.

[0085] FIG. 12 is a flowchart showing an example of the operation of the medium reading process.

[0086] An example of the operation of the medium reading process of the medium conveying device 100 will be described below with reference to the flowchart shown in Fig. 12. The flow of the operation described below is executed mainly by the processing circuit 170 in cooperation with each element of the medium conveying device 100 based on a program stored in advance in the storage device 160.

[0087] First, the control unit 173 waits until the user inputs an instruction to read a medium using the operation device 105 or the information processing device, and an operation signal instructing the reading of a medium is received from the operation device 105 or the interface device 152 (step S201).

[0088] Next, control unit 173 acquires a first medium signal from first medium sensor 111, and determines whether or not a medium is placed on mounting table 103 based on the acquired first medium signal (step S202). If no medium is placed on mounting table 103, control unit 173 ends the series of steps.

[0089] On the other hand, when a medium is placed on the placement table 103, the control unit 173 drives the first motor 121 in accordance with the initial setting value set in the storage device 160 to rotate the cam member 141 and place the cam member 141 in the initial position (step S203). In the same manner as in the process of step S102, the control unit 173 rotates the cam member 141, and after the cam member 141 passes the reference position, drives the first motor 121 by an amount corresponding to the initial setting value, thereby placing the cam member 141 in the initial position. As a result, the pressing force of the separation roller 114 is set to a magnitude that satisfies the specifications of the device.

[0090] Next, second motor 151 is driven to move mounting table 103 to a position where the medium contacts pick roller 112. Control unit 173 drives second motor 151 to rotate pick roller 112, feed roller 113, separation roller 114, and first to eighth transport rollers 117a-h, thereby feeding and transporting the medium placed on mounting table 103 (step S204).

[0091] Next, control unit 173 waits until the leading edge of the medium passes the position of third medium sensor 116 (step S205). Control unit 173 periodically receives a third medium signal from third medium sensor 116, and when the signal value of the third medium signal changes from a value indicating the absence of a medium to a value indicating the presence of a medium, determines that the leading edge of the medium has passed the position of third medium sensor 116.

[0092] Next, control unit 173 calculates the degree of slippage that occurred between the medium and feed roller 113 from the time the leading edge of the medium passed the position of second medium sensor 115 until the time it passed the position of third medium sensor 116 as the slippage degree. Control unit 173 stores the calculated slippage degree in storage device 160 (step S206).

[0093] The control unit 173 acquires the drive amount of the motor that drives the feed roller 113 from the time the leading edge of the medium passes the position of the second medium sensor 115 until it passes the position of the third medium sensor 116. The control unit 173 periodically acquires the second medium signal and the third medium signal from the second medium sensor 115 and the third medium sensor 116, and detects the timing when the leading edge of the medium passes the positions of the second medium sensor 115 and the third medium sensor 116. The control unit 173 acquires the number of pulses of the pulse signal supplied to the second motor 151 to rotate the feed roller 113 from the time the leading edge of the medium passes the position of the second medium sensor 115 until it passes the position of the third medium sensor 116 as the drive amount.

[0094] The control unit 173 calculates the slip degree S according to, for example, the following equation (1). S = (T1 / T2-1) × 100 (1) Here, T1 is the distance the medium is transported by the feed roller 113 from when the leading edge of the medium passes the position of the second medium sensor 115 until it passes the position of the third medium sensor 116. T1 is calculated by multiplying the drive amount obtained above by the transport distance by the feed roller 113 per pulse. T2 is the distance between the positions of the second medium sensor 115 and the third medium sensor 116. In other words, the greater the amount by which the feed roller 113 causes the medium to slip, the greater the degree of slippage.

[0095] Next, control unit 173 waits until the leading edge of the medium passes the position of first conveyor roller 117a (step S207). Control unit 173 determines that the leading edge of the medium has passed the position of first conveyor roller 117a when a predetermined time has elapsed since it was determined in step S205 that the leading edge of the medium has passed the position of third medium sensor 116. The predetermined time is set to a value obtained by adding a margin to the time required for the medium to move from the position of third medium sensor 116 to the position of first conveyor roller 117a.

[0096] Next, the control unit 173 controls the first motor 121 to stop the pick roller 112, the feed roller 113, and the separation roller 114 (step S208). As a result, the medium is subsequently transported by the first transport roller 117a, and the pick roller 112, the feed roller 113, and the separation roller 114 rotate along with the transported medium.

[0097] Next, the control unit 173 causes the imaging device 119 to capture an image of the medium, acquires an input image from the imaging device 119, and outputs the acquired input image by transmitting it to the information processing device via the interface device 152 (step S209).

[0098] Next, control unit 173 determines whether or not a medium remains on mounting table 103 based on the first medium signal received from first medium sensor 111 (step S210).

[0099] If media remain on the mounting table 103, the control unit 173 drives the first motor 121 in accordance with the degree of slippage stored in the storage device 160 to rotate the cam member 141 and change the pressing force of the separation roller 114 (step S211). The medium conveying device 100 stores in advance in the storage device 160 a table indicating the relationship between the degree of slippage and the position of the cam member 141 (the amount of drive of the first motor 121 to place the cam member at that position). The position of the cam member 141 is set to a position where the pressing force of the separation roller 114 increases as the degree of slippage increases. The control unit 173 refers to the table and identifies the amount of drive of the first motor 121 that corresponds to the degree of slippage stored in the storage device 160. Similar to the process of step S203, the control unit 173 rotates the cam member 141, and after the cam member 141 passes the reference position, drives the first motor 121 by the specified drive amount, thereby disposing the cam member 141 at a position according to the degree of slippage. This allows the control unit 173 to increase the pressing force of the separation roller 114 and suppress the occurrence of slippage of the medium when the feed roller 113 wears and the degree of medium slippage increases.

[0100] The control unit 173 may calculate a statistical value such as the average, median, minimum, or maximum value of the slippage degree for a predetermined number of recent times, and specify the drive amount of the first motor 121 corresponding to the calculated statistical value. This allows the control unit 173 to prevent the cam member 141 from being frequently moved due to the influence of a particular medium that is prone to slippage, and allows the medium to be transported stably.

[0101] Next, the control unit 173 controls the first motor 121 to rotate the pick roller 112, the feed roller 113, and the separation roller 114 again (step S212), and then proceeds to step S205 to repeat the processes of steps S205 to S210.

[0102] On the other hand, if there are no media remaining on the mounting table 103, the control unit 173 stops the second motor 151 and the first to eighth transport rollers 117a to 117h (step S213), and ends the series of steps.

[0103] As described above in detail, the medium conveying device 100 has a driving force transmission mechanism 130 that transmits driving force from the first motor 121 to the cam member 141 for pressing the separation roller 114 toward the feed roller 113. The driving force transmission mechanism 130 prevents the cam member 141 from rotating in the reverse direction without flowing a hold current to the first motor 121 to stop the cam member 141. This enables the medium conveying device 100 to continue pressing the separation roller 114 toward the feed roller 113 with an appropriate force while reducing power consumption.

[0104] In addition, the media conveying device 100 is able to appropriately set the separation force of the separation roller 114 without using expensive parts such as an electromagnetic clutch that can switch the torque applied to the separation roller 114, thereby reducing device costs.

[0105] Fig. 13 is a schematic diagram for explaining another driving force transmission mechanism 230. Fig. 13 is a schematic diagram of the driving force transmission mechanism 230 and the pressure applying mechanism 140 as viewed from the upstream side.

[0106] The driving force transmission mechanism 230 is used in place of the driving force transmission mechanism 130. The driving force transmission mechanism 230 has the same structure and mechanism as the driving force transmission mechanism 130. However, the driving force transmission mechanism 230 does not include the worm 132 and the worm wheel 133, and instead includes a first gear 232, a second gear 233, and a torque limiter 235.

[0107] The belt 131 is suspended between the rotation shaft 121a of the first motor 121 and a first gear shaft 232a, which is the rotation shaft of the first gear 232. The first gear 232 is provided so as to mesh with a second gear 233. The second gear 233 is attached to a cam member shaft 134.

[0108] Torque limiter 235 is provided on cam member shaft 134 so as to prevent rotation of cam member shaft 134 until a torque greater than the limit value is applied. The limit value of torque limiter 235 is set to a value greater than the force that rotates cam member 141 in the opposite direction of arrow A22 due to the tensile force of first elastic member 143 and the weight of separation roller 114. First motor 121 rotates cam member shaft 134 via belt 131, first gear 232, and second gear 233 so that torque greater than the limit value is applied to torque limiter 235. On the other hand, when cam member 141 tries to rotate in the opposite direction of arrow A22, the torque applied to torque limiter 235 is smaller than the limit value, and therefore rotation of cam member shaft 134 due to the tensile force of first elastic member 143 and the weight of separation roller 114 is prevented.

[0109] That is, the torque limiter 235 transmits the driving force generated by the first motor 121 from the first motor 121 to the cam member 141, causing the cam member 141 to rotate so as to press the separation roller 114 toward the feed roller 113. On the other hand, the torque limiter 235 is provided so that even if the supply of power to the first motor 121 is cut off, the cam member 141 does not rotate in the opposite direction of the arrow A22, and the cam member 141 continues to press the separation roller 114 toward the feed roller 113. Therefore, the medium conveying device can cut off the supply of power to the first motor 121 after controlling the first motor 121 to set the separation roller 114, thereby reducing power consumption.

[0110] As described above in detail, even when the drive force transmission mechanism 230 has a torque limiter 235, the media conveying device is able to continue to press the separation roller 114 toward the feed roller 113 with an appropriate force while reducing power consumption.

[0111] Fig. 14 is a schematic diagram for explaining yet another driving force transmission mechanism 330. Fig. 14 is a schematic diagram of the driving force transmission mechanism 330 and the pressure applying mechanism 140 as viewed from the upstream side.

[0112] The driving force transmission mechanism 330 is used in place of the driving force transmission mechanism 130. The driving force transmission mechanism 330 has the same structure and mechanism as the driving force transmission mechanism 130. However, the driving force transmission mechanism 330 does not include the worm 132 and the worm wheel 133, and instead includes a first gear 332, a first reduction gear 333, a second reduction gear 335, and a second gear 336.

[0113] Belt 131 is suspended between rotation shaft 121a of first motor 121 and first gear shaft 332a, which is the rotation shaft of first gear 332. First gear 332 meshes with the larger gear of first reduction gear 333, the smaller gear of first reduction gear 333 meshes with the larger gear of second reduction gear 335, and the smaller gear of second reduction gear 335 meshes with second gear 336. Second gear 336 is attached to cam member shaft 134.

[0114] The first reduction gear 333 and the second reduction gear 335 rotate in conjunction with the rotation of the first motor 121, causing the second gear 336, the cam member shaft 134, and the cam member 141 to rotate. Meanwhile, the reduction ratio of the first reduction gear 333 and the second reduction gear 335 is set to a value that prevents the rotation of the second gear 336 when the cam member 141 attempts to rotate in the opposite direction of arrow A22 due to the pulling force of the first elastic member 143 and the weight of the separation roller 114. This prevents the cam member 141 from rotating due to the pulling force of the first elastic member 143 and the weight of the separation roller 114.

[0115] That is, the first reduction gear 333 and the second reduction gear 335 transmit the driving force generated by the first motor 121 from the first motor 121 to the cam member 141, causing the cam member 141 to rotate so as to press the separation roller 114 toward the feed roller 113. Meanwhile, the first reduction gear 333 and the second reduction gear 335 are provided so that even if the supply of power to the first motor 121 is cut off, the cam member 141 does not rotate in the opposite direction of arrow A22, and the cam member 141 continues to press the separation roller 114 toward the feed roller 113. Therefore, after controlling the first motor 121 to set the separation roller 114, the medium conveying device can cut off the supply of power to the first motor 121, thereby reducing power consumption. The number of reduction gears is not limited to two and may be one, three, or more.

[0116] As described above in detail, even when the drive force transmission mechanism 330 has the first reduction gear 333 and the second reduction gear 335, the media conveying device is able to continue to press the separation roller 114 toward the feed roller 113 with an appropriate force while reducing power consumption.

[0117] Fig. 15 is a schematic diagram for explaining yet another driving force transmission mechanism 430 and pressure applying mechanism 440. Fig. 15 is a schematic diagram of the driving force transmission mechanism 430 and pressure applying mechanism 440 as viewed from the upstream side.

[0118] The driving force transmission mechanism 430 is used in place of the driving force transmission mechanism 130. The driving force transmission mechanism 430 has the same structure and mechanism as the driving force transmission mechanism 130. However, the driving force transmission mechanism 430 does not include the worm 132 and the worm wheel 133, but instead includes a ratchet gear 432 and a gear 433. Furthermore, the driving force transmission mechanism 430 includes a cam member shaft 434 in place of the cam member shaft 134.

[0119] Belt 131 is suspended between rotation shaft 121a of first motor 121 and ratchet gear shaft 432a, which is the rotation shaft of ratchet gear 432. Ratchet gear 432 meshes with gear 433. Gear 433 is attached to cam member shaft 434. Cam member shaft 434 is provided so as not to protrude from cam member 441 of pressure applying mechanism 440 on the side opposite to ratchet gear 432.

[0120] 16(A) and (B) are schematic diagrams for explaining the ratchet gear 432. FIG.

[0121] 16(A) and 16(B), the ratchet gear 432 includes a gear portion 432b and a pawl portion 432c. The pawl portion 432c is located opposite the gear portion 432b so as to allow rotation of the gear portion 432b in the direction of arrow A21 while restricting rotation of the gear portion 432b in the opposite direction of arrow A21. This allows the ratchet gear 432 to rotate only in the direction of arrow A21, and the gear 433 and the cam member shaft 434 to rotate only in the direction of arrow A22. Therefore, rotation of the cam member 141 due to the pulling force of the first elastic member 143 and the weight of the separation roller 114 is prevented.

[0122] Figures 17 and 18 are schematic diagrams for explaining the pressure applying mechanism 440. Figures 17 and 18 are side views of the pressure applying mechanism 440 as viewed from the side.

[0123] The pressure applying mechanism 440 is used in place of the pressure applying mechanism 140. The pressure applying mechanism 440 has the same structure and mechanism as the pressure applying mechanism 140. However, the pressure applying mechanism 440 has a cam member 441 instead of the cam member 141.

[0124] Cam member 441 is attached to cam member shaft 434 so as to rotate (swing) in accordance with the rotation of cam member shaft 434. Cam member 441 has an engaging portion 441a and a detected portion 441b. One end of engaging portion 441a is engaged with a protruding portion 441c provided on the surface of cam member 441 opposite ratchet gear 432, and first elastic member 143 is attached to the other end of engaging portion 441a. As a result, protruding portion 441c moves in accordance with the rotation of cam member 441, and engaging portion 441a moves in conjunction with the movement of protruding portion 441c. Detected portion 441b is a plate-like member similar to detected portion 141b, and rotates (swings) in conjunction with the rotation (swing) of cam member 441.

[0125] As shown in Fig. 15, when power is supplied to the first motor 121 and the first motor 121 rotates in the direction of arrow A21, the belt 131 and the ratchet gear 432 rotate in the direction of arrow A21. The rotation of the ratchet gear 432 causes the gear 433 to rotate in the direction of arrow A22, and the cam member 441 rotates in the direction of arrow A22 via the cam member shaft 434. As shown in Figs. 17 and 18, when the cam member 441 rotates in the direction of arrow A22, the protrusion 441c is positioned away from the first engaging member 142d, and the engaging portion 441a pulls the first elastic member 143 in the direction of arrow A23 (upstream). This presses the separation roller 114 toward the feed roller 113.

[0126] On the other hand, when the first motor 121 further rotates in the direction of the arrow A21, the cam member 441 further rotates in the direction of the arrow A22, and the protrusion 441c approaches the first engagement member 142d. This reduces the force applied to the first elastic member 143 by the engagement portion 441a in the direction of the arrow A23. This reduces the force applied to the separation roller 114 pressing the feed roller 113.

[0127] 18, the cam member 441 pulls the first elastic member 143 in the direction of the arrow A23, and conversely, a force in the opposite direction of the arrow A23 is applied to the cam member 441 and the cam member shaft 434 by the first engagement member 142d. However, as described above, the ratchet gear 432 prevents the cam member shaft 434 from rotating in the opposite direction of the arrow A22. Therefore, even if the supply of power to the first motor 121 is cut off, the cam member 441 does not rotate in the opposite direction of the arrow A22, and the cam member 441 continues to press the separation roller 114 toward the feed roller 113.

[0128] When the pressure applying mechanism 440 is used, in step S102 of FIG. 11 and steps S203 and S211 of FIG. 12, the measurement unit 171 or the control unit 173 moves the cam member 441 by rotating the cam member 441 only in one direction (the direction of arrow A22).

[0129] In this way, the ratchet gear 432 transmits the driving force generated by the first motor 121 from the first motor 121 to the cam member 441, causing the cam member 441 to rotate so as to press the separation roller 114 toward the feed roller 113. On the other hand, the ratchet gear 432 is provided so that even if the supply of power to the first motor 121 is cut off, the cam member 441 does not rotate in the opposite direction of the arrow A22, and the cam member 441 continues to press the separation roller 114 toward the feed roller 113. Therefore, after controlling the first motor 121 to set the separation roller 114, the medium conveying device can cut off the supply of power to the first motor 121, thereby reducing power consumption.

[0130] As described above in detail, even when the drive force transmission mechanism 230 has a ratchet gear 432, the media conveying device is able to continue to press the separation roller 114 toward the feed roller 113 with an appropriate force while reducing power consumption.

[0131] Figure 19 is a schematic diagram for explaining yet another driving force transmission mechanism 530 and pressure applying mechanism 440. Figure 19 is a schematic diagram of the driving force transmission mechanism 530 and pressure applying mechanism 440 as viewed from the upstream side.

[0132] The driving force transmission mechanism 530 is used in place of the driving force transmission mechanism 130. The driving force transmission mechanism 530 has the same structure and mechanism as the driving force transmission mechanism 130. However, the driving force transmission mechanism 530 does not include the worm 132 and the worm wheel 133, and instead includes a first gear 532, a second gear 533, and a one-way clutch 535. Furthermore, the driving force transmission mechanism 430 includes a cam member shaft 534 in place of the cam member shaft 134. When the driving force transmission mechanism 530 is used, a pressure applying mechanism 440 is used in place of the pressure applying mechanism 140.

[0133] Belt 131 is suspended between rotation shaft 121a of first motor 121 and first gear shaft 532a, which is the rotation shaft of first gear 532. First gear 532 is provided to mesh with second gear 533. Second gear 533 is attached to cam member shaft 534. Similar to cam member shaft 434, cam member shaft 534 is provided so as not to protrude from cam member 441 of pressure applying mechanism 440 on the side opposite to second gear 533.

[0134] One-way clutch 535 is provided on cam member shaft 534 so as to allow rotation of cam member shaft 534 in the direction of arrow A22 while restricting rotation of cam member shaft 534 in the opposite direction of arrow A22. This prevents rotation of cam member 141 due to the pulling force of first elastic member 143 and the weight of separation roller 114.

[0135] In this way, the one-way clutch 535 transmits the driving force generated by the first motor 121 from the first motor 121 to the cam member 441, causing the cam member 441 to rotate so as to press the separation roller 114 toward the feed roller 113. On the other hand, the one-way clutch 535 is provided so that even if the supply of power to the first motor 121 is cut off, the cam member 441 does not rotate in the opposite direction of the arrow A22, and the cam member 441 continues to press the separation roller 114 toward the feed roller 113. Therefore, the medium conveying device can cut off the supply of power to the first motor 121 after controlling the first motor 121 to set the separation roller 114, thereby reducing power consumption.

[0136] As described above in detail, even when the drive force transmission mechanism 230 has a one-way clutch 535, the media conveying device is able to continue to press the separation roller 114 toward the feed roller 113 with an appropriate force while reducing power consumption.

[0137] FIG. 20 is a diagram showing a schematic configuration of a processing circuit 670 of a medium conveyance device according to another embodiment.

[0138] The processing circuit 670 is used in place of the processing circuit 170 of the medium conveying device 100, and executes setting processing, medium reading processing, and the like in place of the processing circuit 170. The processing circuit 670 includes a measurement circuit 671, a setting circuit 672, and a control circuit 673. Note that each of these components may be configured as an independent integrated circuit, microprocessor, firmware, or the like.

[0139] The measuring circuit 671 is an example of a measuring unit, and has the same function as the measuring unit 171. When the measuring circuit 671 receives an adjustment signal from the operation device 105 or the interface device 152, it controls the first motor 121, receives a cam member signal from the cam member sensor 145, and measures the amount of rotation of the cam member 141 based on the received cam member signal. The measuring circuit 671 outputs the measurement result to the setting circuit 672.

[0140] The setting circuit 672 is an example of a setting unit, and has the same function as the setting unit 172. The setting circuit 672 receives the measurement result of the rotation amount of the cam member 141 from the measurement circuit 671, and sets an initial setting value in the storage device 160 based on the received measurement result.

[0141] The control circuit 673 is an example of a control unit, and has the same functions as the control unit 173. The control circuit 673 reads out initial setting values ​​from the storage device 160, and controls the first motor 121 based on the read out initial setting values. The control circuit 673 also receives an operation signal from the operation device 105 or the interface device 152, a first medium signal from the first medium sensor 111, a second medium signal from the second medium sensor 115, and a third medium signal from the third medium sensor 116. The control circuit 673 controls the second motor 151 based on the received signals, and also acquires an input image from the imaging device 119 and outputs it to the interface device 152.

[0142] As described above in detail, the media conveying device is now able to reduce power consumption and continue to press the separation roller 114 toward the feed roller 113 with an appropriate force, even when the setting process and media reading process are performed by the processing circuit 670. [Explanation of symbols]

[0143] 100 medium conveying device, 113 feeding roller, 114 separation roller, 121 first motor, 130 driving force transmission mechanism, 132 worm, 133 worm wheel, 235 torque limiter, 333 first reduction gear, 335 second reduction gear, 432 ratchet gear, 141, 441 cam member, 142 support member, 143 first elastic member, 144 second elastic member, 171 measuring unit, 172 setting unit

Claims

1. a feeding roller for feeding the medium; a separation roller disposed opposite the feed roller; a motor that generates driving force when supplied with electric power; a cam member that rotates in a first direction in accordance with the driving force to press the separation roller toward the feed roller; a driving force transmission unit provided between the motor and the cam member, which transmits the driving force from the motor to the cam member, and which is provided so that even if the supply of power to the motor is cut off, the cam member does not rotate in a second direction opposite to the first direction, and the cam member continues to press the separation roller toward the feed roller; A medium transport device comprising:

2. The medium transport device according to claim 1 , wherein the driving force transmission unit includes a worm gear including a worm and a worm wheel.

3. The medium transport device according to claim 1 , wherein the driving force transmission unit includes a torque limiter.

4. The medium transport device according to claim 1 , wherein the driving force transmission unit includes a reduction gear.

5. The medium transport device according to claim 1 , wherein the drive force transmission unit includes a ratchet gear.

6. The medium transport device according to claim 1 , wherein the driving force transmission unit includes a one-way clutch.

7. a support portion that supports the separation roller; a first elastic member having one end attached to the cam member and the other end attached to the support portion; 7. The medium transport device according to claim 1, further comprising: a second elastic member having one end fixed and the other end attached to the support portion.

8. a measuring unit for measuring the amount of rotation of the cam member; A medium conveying device as described in any one of claims 1 to 7, further comprising a setting unit that sets a value based on the amount of rotation measured by the measuring unit when an operator sets the position of the cam member.

Images