JP2020105014A - Medium transport device, controlling method, and controlling program - Google Patents

Abstract

To provide a medium transport device that can well transport a medium, a controlling method, and a controlling program.SOLUTION: A medium transport device 100 includes: a transport roller 113 that transports a medium; a braking roller 114 that is provided facing the transport roller; a torque limiter 114b that is provided between a rotational shaft 114a of the braking roller and the braking roller and can change a limit value of a torque on the braking roller in the reverse direction of the medium transport direction; a detection part 154 that detects an inter-medium distance between the media continuously transported by the transport roller; and a controlling part 151 that controls the torque limiter so as to change the limit value based on the inter-medium distance.SELECTED DRAWING: Figure 7

Description

The present invention relates to a medium carrying device, a control method and a control program, and more particularly to a medium carrying device, a control method and a control program for feeding a medium using a feeding roller and a brake roller.

In general, a medium transporting device such as a scanner that transports a medium such as a document uses a feeding roller and a brake roller to feed a plurality of media set on a mounting table while separating them one by one. In such a medium carrying device, when the carrying load (medium separating force) applied to the medium by the brake rollers is small, there is a possibility that double feeding of the medium will occur. On the other hand, if the conveyance load applied to the medium by the brake roller is too large, the paper is likely to slip on the medium when paper dust or the like is attached to the surface of the medium. If the slip amount of the feeding roller is large, the abrasion of the feeding roller progresses, the conveyance speed of the medium decreases, and the possibility of failure of feeding the medium increases. Therefore, the medium carrying device needs to apply a carrying load of an appropriate size to the medium.

A sheet feeding device has been disclosed in which a medium is fed one by one into a device by a separator roller and a brake roller provided in a separation unit (Patent Document 1). This sheet feeding device calculates the slip ratio based on the rotation speed of the separator roller and the amount of medium movement in the separating section, and controls the force acting on the medium separation based on the slip ratio.

A conveyance roll that conveys the recording medium, and a separation roll that is disposed so as to be in pressure contact with the conveyance roll through the recording medium, and has a separation roll to which a separation torque in the opposite direction to the conveyance direction is applied, A sheet feeding device that separates it from other recording media is disclosed (Patent Document 2). This paper feeding device changes the separation torque of the separation roll based on the detection result of the double feeding of the recording medium and the detection result of the slip of the uppermost recording medium with respect to the roll.

JP, 2006-213502, A JP, 2008-303043, A

In the medium transport device, it is desired to feed the medium better.

An object of the present invention is to provide a medium carrying device, a control method and a control program capable of feeding a medium better.

A medium conveying device according to one aspect of the present invention is provided between a feeding roller that feeds a medium, a brake roller that is arranged to face the feeding roller, a rotation shaft of the brake roller, and the brake roller. And a torque limiter capable of changing the limit value of the torque applied to the brake roller in the direction opposite to the medium feeding direction, and a detection unit for detecting the inter-medium distance of the medium continuously fed by the feeding roller. And a control unit that controls the torque limiter so as to change the limit value based on the inter-medium distance.

In addition, a control method according to one aspect of the present invention includes a feeding roller that feeds a medium, a brake roller that is arranged to face the feeding roller, a rotation shaft of the brake roller, and the brake roller. A method for controlling a medium conveying device, comprising: a torque limiter that is provided and that can change a limit value of a torque applied to a brake roller in a direction opposite to a medium feeding direction. Detecting the inter-medium distance of the medium, and controlling the torque limiter to change the limit value based on the inter-medium distance.

In addition, the control program according to one aspect of the present invention includes a feeding roller that feeds a medium, a brake roller that is arranged to face the feeding roller, a rotation shaft of the brake roller, and the brake roller. A control program for a medium transport device, comprising: a torque limiter that is provided and that can change the limit value of the torque applied to the brake roller in the direction opposite to the medium feed direction. The medium conveying device is caused to detect the inter-medium distance of the medium and control the torque limiter so as to change the limit value based on the inter-medium distance.

According to the present invention, the medium carrying device, the control method, and the control program can feed the medium better.

FIG. 3 is a perspective view showing the medium carrying device 100. 6 is a diagram for explaining a transport path inside the medium transport device 100. FIG. It is a schematic diagram which shows an example of the relationship between a current value and torque. 3 is a block diagram showing a schematic configuration of the medium carrying device 100. FIG. 3 is a diagram showing a schematic configuration of a storage device 140 and a CPU 150. FIG. 9 is a flowchart illustrating an example of operation of medium reading processing. It is a flow chart which shows an example of operation of torque control processing. It is a figure for explaining a drive mechanism concerning other embodiments. It is a figure which shows schematic structure of the processing circuit 260 which concerns on other embodiment.

Hereinafter, a medium carrying device according to one aspect of the present invention will be described with reference to the drawings. However, it should be noted that the technical scope of the present invention is not limited to those embodiments, but extends to the inventions described in the claims and their equivalents.

FIG. 1 is a perspective view showing a medium carrying device 100 configured as an image scanner. The medium carrying device 100 carries a medium, which is a document, and picks up an image. The medium is paper, cardboard, a card, or the like. The medium carrying device 100 may be a facsimile, a copying machine, a printer multifunction peripheral (MFP, Multifunction Peripheral), or the like. The medium to be conveyed may be an object to be printed or the like instead of a document, and the medium conveying device 100 may be a printer or the like.

The medium carrying device 100 includes an upper housing 101, a lower housing 102, a mounting table 103, a discharge table 104, an operating device 105, a display device 106, and the like.

The upper housing 101 is disposed on the upper side of the medium carrying device 100, and is engaged with the lower housing 102 by a hinge so that it can be opened and closed when the medium is clogged and when the inside of the medium carrying device 100 is cleaned.

The mounting table 103 is engaged with the lower housing 102 so that a medium to be conveyed can be mounted. The mounting table 103 is provided on a side surface of the lower housing 102 on the medium supply side so as to be movable in a substantially vertical direction A1. The mounting table 103 is arranged at the lower end position so that the medium is easily placed when the medium is not conveyed, and the medium is conveyed so that the placed medium is fed when the medium is conveyed. It rises to almost the same height as the road. The ejection table 104 is formed on the upper housing 101 so as to be able to hold the ejected medium. The ejection tray 104 has an auxiliary ejection tray 104a that holds the medium by being pulled out from the ejection tray 104 when necessary.

The operation device 105 has an input device such as a button and an interface circuit that acquires a signal from the input device, receives an input operation by a user, and outputs an operation signal according to the input operation by the user. The display device 106 has a display including liquid crystal, organic EL (Electro-Luminescence), etc., and an interface circuit for outputting image data to the display, and displays the image data on the display.

FIG. 2 is a diagram for explaining a transport path inside the medium transport device 100.

The conveyance path inside the medium conveyance device 100 includes a first medium detection sensor 111, a pick roller 112, a feeding roller 113, a brake roller 114, a movement distance detection sensor 115, a second medium detection sensor 116, and first to eighth conveyance rollers. 117a to h, first to eighth driven rollers 118a to 118h, a first imaging device 119a, a second imaging device 119b, and the like. The number of each of the pick roller 112, the feeding roller 113, the brake roller 114, the first to eighth transport rollers 117a to h, and/or the first to eighth driven rollers 118a to 118h is not limited to one. There may be more than one. In that case, the plurality of pick rollers 112, the feeding roller 113, the brake roller 114, the first to eighth conveying rollers 117a to h and/or the first to eighth driven rollers 118a to 118h are orthogonal to the medium conveying direction A2. It is arranged side by side with a space in the direction.

The surface of the upper housing 101 facing the lower housing 102 forms the first guide 101a of the medium transport path, and the surface of the lower housing 102 facing the upper housing 101 is the medium transport path. The second guide 102a is formed. In FIG. 2, arrow A2 indicates the medium transport direction, and arrow A3 indicates the medium discharge direction. In the following, upstream means upstream in the medium carrying direction A2 or medium discharging direction A3, and downstream means downstream in the medium carrying direction A2 or medium discharging direction A3.

The first medium detection sensor 111 is arranged on the mounting table 103, that is, on the upstream side of the feeding roller 113 and the brake roller 114, and detects the mounting state of the medium on the mounting table 103. The first medium detection sensor 111 detects whether or not the medium is placed on the mounting table 103 by a contact detection sensor that sends a predetermined current when the medium is in contact with the medium or when the medium is not in contact. To determine. The first medium detection sensor 111 generates and outputs a first medium detection signal whose signal value changes depending on whether a medium is placed on the placing table 103 or not.

The pick roller 112 is provided in the upper housing 101, contacts the medium placed on the mounting table 103 that has risen to approximately the same height as the medium transport path, and feeds the medium in the medium transport direction A2. To do.

The feeding roller 113 is provided in the upper housing 101 on the downstream side of the pick roller 112 in the medium carrying direction A2, and further feeds the medium fed by the pick roller 112 toward the medium carrying direction A2. ..

The brake roller 114 is arranged in the lower housing 102 so as to face the feeding roller 113. The feeding roller 113 and the brake roller 114 perform a medium separating operation, separate the medium, and feed the sheets one by one.

A shaft 114a is connected to the center of rotation of the brake roller 114, and the shaft 114a is connected to a drive device described later via a transmission mechanism such as a gear and a pulley (not shown). The shaft 114a is an example of the rotating shaft of the brake roller 114, and the driving force generated by the drive device is transmitted from the drive device to the brake roller 114 via the shaft 114a.

Further, a torque limiter 114b is provided between the shaft 114a and the brake roller 114. The torque limiter 114b is provided so that the limit value of the torque applied to the brake roller 114 in the direction A6 opposite to the medium feeding direction can be changed according to the control signal from the CPU. As the torque limiter 114b, for example, a known hysteresis brake having a rotor and a stator including magnetic poles excited by a coil is used. In the hysteresis brake, the magnitude of the magnetic field generated between the rotor and the stator changes according to the magnitude of the current supplied to the coil, and the magnitude of the magnetic friction generated when the rotor rotates. As a result, the braking force of the rotor changes.

FIG. 3 is a schematic diagram showing an example of the relationship between the current value and the torque in the hysteresis brake. The horizontal axis of FIG. 3 represents the current value and the vertical axis represents the torque. As shown in FIG. 3, the larger the current supplied to the coil, the larger the torque in the hysteresis brake. The medium conveyance device 100 uses a hysteresis brake as the torque limiter 114b, and changes the magnitude of the current supplied to the torque limiter 114b to limit the torque applied to the brake roller 114 in the direction A6 opposite to the medium feeding direction. Can be changed.

The moving distance detection sensor 115 is arranged on the downstream side of the feeding roller 113 and the brake roller 114 and on the upstream side of the second medium detection sensor 116, particularly in the vicinity of the feeding roller 113 and the brake roller 114, and the medium to be fed. The moving distance of. The moving distance detection sensor 115 includes an optical rotary encoder. The rotary encoder includes a disc provided with a large number of slits (light transmission holes) and rotated according to a medium to be fed, and a light emitter provided so as to face each other with the disc interposed therebetween. And a light receiver. The light receiver is a moving distance of the outer peripheral surface of the rotary encoder according to the number of changes in a state in which a slit is present between the light emitter and the light receiver, and a state in which the slit is not present and is shielded by the disc. That is, the moving distance signal indicating the moving distance of the medium to be fed is generated and output.

The moving distance detection sensor 115 may detect the moving distance of the medium to be fed by using a light emitter and a light receiver provided on one side of the medium transport path. The light emitter is an LED (Light Emitting Diode) or the like, and emits light toward the medium transport path. On the other hand, the light receiver captures an image corresponding to the received light at regular intervals and detects the common part from the latest image and the immediately preceding image. The light receiver detects the movement distance of the conveyed medium in the medium conveyance direction based on the detected change in the position of the common portion in the image, and generates and outputs a movement distance signal indicating the detected movement distance.

The second medium detection sensor 116 is arranged on the downstream side of the moving distance detection sensor 115 and on the upstream side of the first transport roller 117a and the first driven roller 118a, particularly in the vicinity of the feeding roller 113 and the brake roller 114, and the position thereof. To detect the media fed to the. The second medium detection sensor 116 has a light emitter 116a and a light receiver 116b. The light emitter 116a and the light receiver 116b are provided in the vicinity of the medium transport path and face each other across the medium transport path. The light emitter 116a is an LED or the like and emits light toward the medium transport path. When there is no medium in the medium conveyance path, the light receiver 116b detects the light emitted from the light emitter 116a. On the other hand, when the medium is present in the medium transport path, the light emitted from the light emitter 116a is blocked by the medium present in the medium transport path, and the light receiver 116b does not detect the light emitted from the light emitter 116a. Based on the intensity of the received light, the light receiver 116b generates and outputs a second medium detection signal whose signal value changes depending on whether or not the medium is present at the position of the second medium detection sensor 116. ..

The light emitter and the light receiver may be provided on the same side with respect to the medium transport path. In that case, the time until the light received by the light receiver is received by the light receiver when the light is reflected by the medium existing in the medium transport path and when it is reflected by the second guide 102a of the lower housing 102. And is different. The light receiver generates the second medium detection signal according to the time from when the light emitter emits light to when the light receiver receives the light. Further, the second medium detection sensor 116 may detect the presence of the medium by a contact detection sensor or the like that sends a predetermined current when the medium is in contact with the medium or when the medium is not in contact. Further, the medium carrying device 100 may detect the presence of the medium by using the movement distance detection sensor 115 instead of the second medium detection sensor 116. In that case, the movement distance detection sensor 115 determines that the medium exists when the movement of the medium is detected, and determines that the medium does not exist when the movement of the medium is not detected.

The first image pickup device 119a has a reduction optical system type image pickup sensor including an image pickup element formed of a CCD (Charge Coupled Device) linearly arranged in the main scanning direction. Further, the first image pickup device 119a has a light source that emits light, a lens that forms an image on the image pickup element, and an A/D that amplifies an electric signal output from the image pickup element and performs analog/digital (A/D) conversion. And a D converter. In the first imaging device 119a, the imaging sensor images the surface of the conveyed medium to generate and output an analog image signal, and the A/D converter A/D converts the analog image signal. To generate and output a digital input image.

Similarly, the second image pickup device 119b has a reduction optical system type image pickup sensor including an image pickup element formed of a CCD linearly arranged in the main scanning direction. Further, the second imaging device 119b includes a light source that irradiates light, 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. Have. In the second imaging device 119b, the imaging sensor images the back surface of the conveyed medium to generate and output an analog image signal, and the A/D converter A/D converts the analog image signal. To generate and output a digital input image.

It should be noted that only one of the first image pickup device 119a and the second image pickup device 119b may be arranged and only one side of the medium may be read. Further, instead of the CCD, a CIS (Contact Image Sensor) of the same-magnification optical system type including an image pickup device made of CMOS (Complementary Metal Oxide Semiconductor) may be used. Hereinafter, the first imaging device 119a and the second imaging device 119b may be collectively referred to as the imaging device 119.

The pick roller 112 and the feeding roller 113 rotate in the medium feeding directions A4 and A5, respectively, so that the medium placed on the mounting table 103 passes between the first guide 101a and the second guide 102a in the medium conveying direction A2. Be transported towards. On the other hand, when a plurality of media are placed on the placing table 103 by rotating the brake roller 114 in the direction A6 opposite to the medium feeding direction, among the mediums placed on the placing table 103, the feeding roller Only the medium in contact with 113 is separated.

The medium is guided by the first guide 101a and the second guide 102a, and the first to third transport rollers 117a to 117c rotate in the directions of arrows A7 to A9, respectively, so that the imaging position L1 of the first imaging device 119a. Sent to. After that, the medium is fed between the fourth transport roller 117d and the fourth driven roller 118d, and is transported to the imaging position L2 of the second imaging device 119b by the rotation of the fourth transport roller 117d in the direction of arrow A10. The medium read by each imaging device 119 is discharged onto the discharge tray 104 by the fifth to eighth transport rollers 117e to 117h rotating in the directions of arrows A11 to A14, respectively.

FIG. 4 is a block diagram showing a schematic configuration of the medium carrying device 100.

The medium carrying device 100 further includes a drive device 131, an interface device 132, a storage device 140, a CPU (Central Processing Unit) 150, a processing circuit 160, and the like in addition to the above-described configuration.

The drive device 131 includes one or more motors. The drive device 131 rotates the pick roller 112, the feeding roller 113, the brake roller 114, and the first to eighth transport rollers 117a to 117h to perform a medium transport operation in response to a control signal from the CPU 150.

The interface device 132 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, personal computer, personal digital assistant, etc.) to read a read image and various information. Send and receive. Further, instead of the interface device 132, a communication unit having an antenna for transmitting/receiving a wireless signal and a wireless communication interface circuit for transmitting/receiving a signal through a wireless communication line according to a predetermined communication protocol may be used. The predetermined communication protocol is, for example, a wireless LAN (Local Area Network).

The storage device 140 includes a memory device such as a RAM (Random Access Memory) and a ROM (Read Only Memory), a fixed disk device such as a hard disk, or a portable storage device such as a flexible disk and an optical disk. The storage device 140 also stores computer programs, databases, tables, and the like used for various processes of the medium carrying device 100. The computer program may be installed in the storage device 140 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 disk read only memory) or a DVD-ROM (digital versatile disk read only memory). Further, the storage device 140 stores an input image or the like as data.

The CPU 150 operates based on a program stored in the storage device 140 in advance. A DSP (digital signal processor), an LSI (large scale integration), or the like may be used instead of the CPU 150. Further, instead of the CPU 150, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or the like may be used.

The CPU 150 includes an operating device 105, a first medium detection sensor 111, a torque limiter 114b, a moving distance detection sensor 115, a second medium detection sensor 116, an image pickup device 119, a drive device 131, an interface device 132, a storage device 140, and a processing circuit 160. Connected with etc. The CPU 150 controls these units. The CPU 150 performs drive control of the drive device 131, medium reading control of the imaging device 119, and the like, and acquires an input image. Further, the CPU 150 changes the torque limit value of the torque limiter 114b based on each signal generated by the moving distance detection sensor 115 or the second medium detection sensor 116.

The processing circuit 160 performs predetermined image processing on the read image acquired from the imaging device 119. The processing circuit 160 stores the read image subjected to the image processing in the storage device 140. An LSI, DSP, ASIC, FPGA, or the like may be used as the processing circuit 160.

FIG. 5 is a diagram showing a schematic configuration of the storage device 140 and the CPU 150.

As shown in FIG. 5, the storage device 140 stores programs such as a control program 141, an image acquisition program 142, a calculation program 143, and a detection program 144. Each of these programs is a functional module implemented by software operating on the processor. The CPU 150 functions as the control unit 151, the image acquisition unit 152, the calculation unit 153, and the detection unit 154 by reading the programs stored in the storage device 140 and operating according to the read programs.

FIG. 6 is a flowchart showing an example of the operation of the medium reading process.

Hereinafter, an example of the operation of the medium reading process of the medium carrying apparatus 100 will be described with reference to the flowchart shown in FIG. The operation flow described below is executed mainly by the CPU 150 in cooperation with each element of the medium carrying device 100 based on a program stored in the storage device 140 in advance.

First, the control unit 151 waits until a user inputs a medium reading instruction using the operation device 105 and receives an operation signal instructing medium reading from the operation device 105 (step S101).

Next, the control unit 151 acquires the first medium detection signal from the first medium detection sensor 111 and determines whether or not a medium is placed on the mounting table 103 based on the obtained first medium detection signal. Yes (step S102). When the medium is not placed on the mounting table 103, the control unit 151 returns the process to step S101 and waits until a new operation signal is received from the operation device 105.

On the other hand, when the medium is placed on the placing table 103, the control unit 151 drives the driving device 131 (step S103). The control unit 151 rotates the pick roller 112, the feeding roller 113, the brake roller 114, and the first to eighth transport rollers 117 a to h to feed and transport the medium placed on the mounting table 103.

Next, the image acquisition unit 152 causes the imaging device 119 to capture an image of the conveyed medium and acquires an input image (step S104).

The image acquisition unit 152 determines whether the leading edge of the medium has reached the image capturing position L1 of the first image capturing device 119a or the image capturing position L2 of the second image capturing device 119b, depending on whether or not a predetermined time has elapsed after the medium was started to be conveyed. Determine whether or not. The medium carrying device 100 is provided with a medium detection sensor in the vicinity of the image pickup position L1 or the image pickup position L2, and based on the medium detection signal received from each medium detection sensor, the leading end of the medium is the image pickup position L1 or the image pickup position L2. It may be determined whether or not has been reached. Each medium detection sensor is a sensor similar to the second medium detection sensor 116. When it is determined that the leading end of the medium has reached the imaging position L1, the image acquisition unit 152 causes the first imaging device 119a to start imaging the medium. On the other hand, when determining that the front end of the medium has reached the imaging position L2, the image acquisition unit 152 causes the second imaging device 119b to start imaging the medium. When the imaging of the medium is completed, the image acquisition unit 152 acquires the input image from the imaging device 119.

Next, the image acquisition unit 152 transmits the acquired input image to the information processing device (not shown) via the interface device 132 (step S105).

Next, the control unit 151 determines whether or not the medium remains on the mounting table 103 based on the first medium detection signal received from the first medium detection sensor 111 (step S106).

When the medium remains on the mounting table 103, the CPU 150 executes the torque control process (step S107), returns the process to step S104, and repeats the processes of steps S104 to S107. Details of the torque control process will be described later.

On the other hand, when no medium remains on the mounting table 103, the control unit 151 stops the driving device 131 to stop the rotation of each roller (step S108), and ends the series of steps.

FIG. 7 is a flowchart showing an example of the operation of the torque control process.

The operation flow shown in FIG. 7 is executed in step S107 of the flowchart shown in FIG.

First, the calculation unit 153 calculates the slip ratio between the feeding roller 113 and the medium to be fed (step S201). The slip ratio indicates the degree to which the medium slips on the outer peripheral surface of the feeding roller 113 and the medium does not move despite the rotation of the feeding roller 113.

The calculation unit 153 calculates the moving distance of the outer peripheral surface of the feeding roller 113 by multiplying the time when the control unit 151 rotates the feeding roller 113 and the peripheral speed of the feeding roller 113. Note that the calculation unit 153 multiplies the number of pulses by which the control unit 151 has driven the driving device 131 by the moving distance of the outer peripheral surface of the feeding roller 113 per pulse, and thereby the outer peripheral surface of the feeding roller 113 is calculated. The moving distance may be calculated. Further, the calculation unit 153 receives the moving distance signal from the moving distance detecting sensor 115, and specifies the moving distance of the medium to be fed from the received moving distance signal. The calculation unit 153 calculates the slip ratio according to the following equation (1) based on the moving distance of the outer peripheral surface of the feeding roller 113 and the moving distance of the medium to be fed.
(Slip ratio)=1-(moving distance of fed medium)/(moving distance of outer peripheral surface of feeding roller 113) (1)

Next, the control unit 151 calculates whether or not the calculated slip ratio is equal to or higher than a predetermined ratio (step S202). The predetermined rate is set in advance based on the medium reading speed (processing speed) guaranteed by the medium carrying device 100, and is set to, for example, 0.3.

When the slip ratio is equal to or higher than the predetermined ratio, the control unit 151 controls the torque limiter 114b so as to decrease the torque limit value of the torque limiter 114b (step S203), and ends the series of steps. The control unit 151 controls the torque limiter 114b by transmitting a control signal instructing the decrease of the torque limit value to the torque limiter 114b. For example, when the torque limit value can be set in five steps in the torque limiter 114b, the control unit 151 decreases the torque limit value by one step. Note that the torque limit value is set to the lower limit value, and when the current torque limit value is the lower limit value, the control unit 151 may omit the torque limit value changing process.

On the other hand, when the slip ratio is less than the predetermined ratio, the control unit 151 determines whether or not the medium conveyed this time is the second medium or later (step S204). When the medium conveyed this time is the first medium, the control unit 151 ends the series of steps.

On the other hand, when the medium conveyed this time is the second medium or later, the detecting unit 154 detects the inter-medium distance of the medium continuously fed by the feeding roller 113 (step S205).

The detection unit 154 periodically receives the second medium detection signal from the second medium detection sensor 116, and this time after the rear end of the medium conveyed immediately before has passed the position of the second medium detection sensor 116. The non-conveying period until the leading edge of the conveyed medium passes is detected. The detection unit 154 changes the signal value of the second medium detection signal from a value indicating that the medium is present at the time when the medium was conveyed immediately before to a value indicating that the medium is not present, and then confirms that the medium is present again. The period until the value changes to the indicated value is detected as the non-conveyance period. The detection unit 154 calculates the inter-medium distance by multiplying the length of the non-conveyance period and the peripheral speed of the feeding roller 113. The calculating unit 153 calculates the inter-medium distance by multiplying the number of pulses by which the control unit 151 has driven the driving device 131 during the non-conveying period and the moving distance of the outer peripheral surface of the feeding roller 113 per pulse. It may be calculated.

Next, the control unit 151 calculates whether or not the detected inter-medium distance is equal to or greater than a predetermined distance (step S206). The predetermined distance is set to a distance between the medium-to-medium distance detected when double feed occurs and the medium-to-medium distance detected when double feed does not occur by an experiment in which the medium is repeatedly conveyed. It is set to 73 mm.

When the inter-medium distance is less than the predetermined distance, the control unit 151 controls the torque limiter 114b so as to increase the torque limit value of the torque limiter 114b (step S207), and ends the series of steps. The control unit 151 controls the torque limiter 114b by transmitting a control signal instructing the torque limit value to increase to the torque limiter 114b. For example, when the torque limit value can be set in five steps in the torque limiter 114b, the control unit 151 increases the torque limit value by one step. An upper limit is set for the torque limit value, and when the current torque limit value is the upper limit, the control unit 151 may omit the torque limit value changing process.

On the other hand, when the inter-medium distance is equal to or greater than the predetermined distance, the control unit 151 determines whether the number of continuous media whose slip ratio is less than the predetermined ratio is equal to or greater than the predetermined number (step S208).

When the number of continuous media whose slip ratio is less than the predetermined ratio is the predetermined number or more, the control unit 151 controls the torque limiter 114b to increase the torque limit value of the torque limiter 114b (step S207), and End the step. The control unit 151 controls the torque limiter 114b in the same manner as when the inter-medium distance is less than the predetermined distance.

On the other hand, when the number of continuous media whose slip ratio is less than the predetermined ratio is less than the predetermined number of times, the control unit 151 does not change the torque limit value of the torque limiter 114b (step S209) and ends the series of steps. To do.

In this way, the control unit 151 controls the torque limiter 114b so as to change the torque limit value of the torque limiter 114b based on the inter-medium distance and/or the slip ratio. As a result, the control unit 151 can automatically set the torque limit value for the medium to be subsequently fed to a more appropriate value in accordance with the behavior of the medium being fed, and the medium can be conveyed better.

In particular, when the slip ratio is equal to or higher than the predetermined ratio, the control unit 151 controls the torque limiter 114b to decrease the limit value regardless of the medium distance (steps S202 and S203).

As a result, the control unit 151 can reduce the conveyance load applied to the medium by the brake roller 114 during the subsequent feeding of the medium, and can suppress the feeding roller 113 from slipping on the medium. By suppressing the slip of the feeding roller 113, the abrasion of the feeding roller 113 is suppressed. Further, the slip of the feeding roller 113 is suppressed, so that the conveyance speed of the medium is suppressed from decreasing. Further, the brake roller 114 reduces the transport load on the medium and suppresses the slip of the feeding roller 113, so that the medium can be fed without entering between the feeding roller 113 and the brake roller 114. Failure is suppressed. As a result, the medium transport apparatus 100 can suppress a decrease in processing speed as a whole and a decrease in processing performance. Further, the user does not need to reset the medium that has failed to be fed, and the medium carrying device 100 can improve the convenience of the user.

Further, when the inter-medium distance is less than the predetermined distance, the control unit 151 controls the torque limiter 114b to increase the limit value (steps S206 and S207).

When the leading end of the medium being fed is separated by the feeding roller 113 and the brake roller 114 and has passed the nip position, the leading end of the medium to be fed next may approach the vicinity of the nip position. As a result of carrying out an experiment in which the medium is repeatedly conveyed, when the leading edge of the medium being fed passes through the nip position, the closer the leading edge of the medium to be fed next is to the nip position, the more the double feeding will occur. It turned out that it is likely to occur. Further, at that time, the closer the leading end position of the medium to be fed next to the nip position, the shorter the inter-medium distance between the medium being fed and the medium to be fed next. When the inter-medium distance is less than the predetermined distance, the control unit 151 considers that there is a sign that double feeding of the medium will occur, and increases the limit value of the torque limiter 114b. As a result, the control unit 151 can increase the conveyance load applied to the medium by the brake roller 114 when the medium is subsequently conveyed, and can suppress the double feeding of the medium.

Further, the control unit 151 controls the torque limiter 114b so as to increase the limit value based on the slip ratios of a plurality of media. In particular, the control unit 151 controls the torque limiter 114b to increase the limit value regardless of the inter-medium distance when the number of continuous media having the slip ratio less than the predetermined ratio is the predetermined number or more (step S208). , S207). As a result, the control unit 151 can increase the conveyance load applied to the medium by the brake roller 114 during the subsequent conveyance of the medium, and the conveyance load applied to the medium by the brake roller 114 is too small, so that double feeding of the medium is performed. It can be suppressed from occurring.

Note that the control unit 151 immediately decreases the limit value of the torque limiter 114b when the slip ratio of the medium to be fed is equal to or higher than the predetermined ratio even once (steps S202 and S203). It is possible to prevent the occurrence more reliably. On the other hand, since the control unit 151 increases the limit value of the torque limiter 114b when the slip ratios of a plurality of media are continuously less than the predetermined ratio (steps S208 and S209), the limit value is frequently changed. Can be suppressed.

The control unit 151 omits the processing of steps S201 to S203 and/or S208 and controls the torque limiter 114b to change the limit value based on only the inter-medium distance without using the slip ratio. May be.

Further, in step S208, the control unit 151 does not increase the limit value when the number of continuous media whose slip ratio is less than the predetermined ratio is equal to or more than the predetermined number of times, and instead of the average value of the slip ratio of the latest predetermined number of times. The limit value may be increased when is less than the predetermined rate. As a result, the control unit 151 can control the torque limiter 114b so that double feeding of the medium is less likely to occur.

Further, in step S206, the control unit 151 does not increase the limit value when the inter-medium distance of the medium related to one combination is less than the predetermined distance, but the inter-medium distances of the media related to the latest plurality of combinations are not increased. The limit value may be increased when the distance is a predetermined distance or more. Accordingly, the control unit 151 can change the limit value to an appropriate value with higher accuracy.

As described above in detail, the medium carrying device 100 changes the limit value of the torque applied to the brake roller 114 in the opposite direction to the medium feeding direction based on the inter-medium distance of continuously fed media. Suppress double feed. As a result, the medium carrying device 100 can feed the medium better.

FIG. 8 is a schematic diagram for explaining a drive mechanism of a medium carrying device according to another embodiment. FIG. 8 is a schematic view of the drive mechanism of the medium transport device viewed from the upstream side in the medium transport direction A2.

As shown in FIG. 8, the medium carrying device has a feed roller 213 and a brake roller 214 instead of the feed roller 113 and the brake roller 114. The feeding roller 213 includes a plurality of feeding rollers 213a and 213b that are arranged side by side in the direction A15 orthogonal to the medium conveying direction with a space therebetween. The brake roller 214 includes a plurality of brake rollers 214a and 214b arranged side by side in the direction A15 orthogonal to the medium transport direction with a space therebetween.

Further, the medium carrying device has first to fourth gears 221a to 221d, first to third shafts 222a to 222c, first to second torque limiters 223a to 223b, and the like.

The first gear 221a is connected to a first motor (not shown) via a drive mechanism including a first electromagnetic clutch, and is engaged with the second gear 221b. The second gear 221b is attached to one end of the first shaft 222a, and the other end of the first shaft 222a is attached to the brake roller 214a via the first torque limiter 223a so as to rotate according to the rotation of the first shaft 222a. There is. On the other hand, the third gear 221c is connected to a second motor (not shown) via a drive mechanism including a second electromagnetic clutch and is engaged with the fourth gear 221d. The fourth gear 221d is attached to one end of the second shaft 222b, and the other end of the second shaft 222b is attached to the brake roller 214b via the second torque limiter 223b so as to rotate according to the rotation of the second shaft 222b. There is.

The brake rollers 214a and 214b are connected not via the first and second torque limiters 223a and 223b but via the third shaft 222c so that each brake roller rotates in accordance with the rotation of the other brake roller. There is. The torque limit value of the first torque limiter 223a is the first limit value, and the torque limit value of the second torque limiter 223b is the second limit value larger than the first limit value. The first motor generates a first driving force for rotating the first gear 221a, and the second motor generates a second driving force for rotating the third gear 221c.

The control unit 151 stops the generation of the second driving force by the second motor and reduces the first driving force by the first motor when the limit value is decreased in step S203 of FIG. 7 while the second driving force is being generated by the second motor. Generate a first driving force in the motor. Since the first driving force is transmitted to each brake roller 214 via the first torque limiter 223a and not via the second torque limiter 223b, the torque applied to each brake roller 214 in the direction A6 opposite to the medium feeding direction. The limit value of is decreased. In this case, the control unit 151 turns off the second electromagnetic clutch to cut off the transmission of the driving force between the second motor and the third gear 221c.

On the other hand, the control unit 151 stops the generation of the first driving force by the first motor when increasing the limit value in step S207 of FIG. 7 while the first driving force is being generated by the first motor, and A second driving force is generated in the second motor. The second driving force is transmitted to each brake roller 214 via the second torque limiter 223b and not via the first torque limiter 223a, so that the torque applied to each brake roller 214 in the direction A6 opposite to the medium feeding direction. The limit value of increases. In this case, the control unit 151 turns off the first electromagnetic clutch to cut off the transmission of the driving force between the first motor and the first gear 221a.

As described above in detail, the medium carrying device can feed the medium better even when the drive mechanism is switched to change the torque limit value.

FIG. 9 is a diagram showing a schematic configuration of a processing circuit 260 of a medium carrying device according to still another embodiment.

The processing circuit 260 is used instead of the processing circuit 160 of the medium carrying device 100, and executes the medium reading process instead of the CPU 150. The processing circuit 260 includes a control circuit 261, an image acquisition circuit 262, a calculation circuit 263, a detection circuit 264, and the like. Note that each of these units may be configured by an independent integrated circuit, microprocessor, firmware, or the like.

The control circuit 261 is an example of a control unit and has the same function as the control unit 151. The control circuit 261 receives an operation signal from the operation device 105, a first medium detection signal from the first medium detection sensor 111, a slip ratio from the calculation circuit 263, and an inter-medium distance from the detection circuit 264. The control circuit 261 controls the drive device 131 and the torque limiter 114b based on the received information.

The image acquisition circuit 262 is an example of an image acquisition unit and has the same function as the image acquisition unit 152. The image acquisition circuit 262 receives an input image from the imaging device 119, stores the received input image in the storage device 140, or outputs the input image to the interface device 132.

The calculation circuit 263 is an example of a calculation unit and has the same function as the calculation unit 153. The calculation circuit 263 receives the movement distance signal from the movement distance detection sensor 115, calculates the slip ratio based on the movement distance signal, and outputs it to the control circuit 261.

The detection circuit 264 is an example of a detection unit and has the same function as the detection unit 154. The detection circuit 264 receives the second medium detection signal from the second medium detection sensor 116, detects the inter-medium distance based on the second medium detection signal, and outputs it to the control circuit 261.

As described above in detail, the medium carrying device can feed the medium better even when the medium reading process is executed by the processing circuit 260.

100 Medium Conveying Device 113 Feeding Roller 114 Brake Roller 114a Shaft 114b Torque Limiter 115 Moving Distance Detection Sensor 151 Control Section 153 Calculation Section 154 Detection Section

Claims (9)

A feeding roller for feeding the medium,
A brake roller arranged to face the feed roller,
A torque limiter that is provided between the rotation axis of the brake roller and the brake roller, and that can change the limit value of the torque applied to the brake roller in the direction opposite to the medium feeding direction;
A detection unit that detects the distance between the media continuously fed by the feed roller;
A control unit that controls the torque limiter so as to change the limit value based on the inter-medium distance;
A medium carrying device comprising: The medium conveyance device according to claim 1, wherein the control unit controls the torque limiter to increase the limit value when the inter-medium distance is less than a predetermined distance. Further comprising a calculating unit for calculating a slip ratio between the feeding roller and the medium to be fed,
The medium conveyance device according to claim 1, wherein the control unit controls the torque limiter so as to change the limit value based on the slip ratio. Further comprising a sensor for detecting a moving distance of the medium to be fed,
The medium carrying device according to claim 3, wherein the calculating unit calculates the slip ratio based on a moving distance of an outer peripheral surface of the feeding roller and a moving distance of the fed medium. The medium conveyance device according to claim 3, wherein the control unit controls the torque limiter so as to decrease the limit value regardless of the inter-medium distance when the slip ratio is equal to or higher than a predetermined ratio. .. The medium conveyance device according to claim 3, wherein the control unit controls the torque limiter so as to increase the limit value based on the slip ratios of a plurality of media. The control unit controls the torque limiter so as to increase the limit value regardless of the inter-medium distance when the number of continuous media whose slip ratio is less than a predetermined ratio is a predetermined number or more. Item 6. The medium carrying device according to item 6. A feeding roller that feeds a medium, a brake roller that is arranged to face the feeding roller, a rotation shaft of the brake roller, and the brake roller, and the medium is attached to the brake roller. A method of controlling a medium carrying device, comprising: a torque limiter capable of changing a limit value of torque applied in a direction opposite to a feeding direction,
Detecting the inter-medium distance of the medium continuously fed by the feeding roller,
Controlling the torque limiter to change the limit value based on the inter-medium distance,
A control method comprising: A feeding roller that feeds a medium, a brake roller that is arranged to face the feeding roller, a rotation shaft of the brake roller, and the brake roller, and the medium is attached to the brake roller. A control program for a medium carrying device, comprising: a torque limiter capable of changing a limit value of torque applied in a direction opposite to a feeding direction,
Detecting the inter-medium distance of the medium continuously fed by the feeding roller,
Controlling the torque limiter to change the limit value based on the inter-medium distance,
A control program for causing the medium carrying device to execute the above.

Images