MEDIUM CONVEYING DEVICE, MEDIUM CONVEYING METHOD, AND IMAGE FORMING APPARATUS

Abstract

To provide a medium conveyance device capable of highly accurate conveyance when conveying a long medium.SOLUTION: Position detecting means outputs a first signal when a tension applying member is at a position indicating an upper limit value of a path length of a medium conveyance path, the tension applying member has first position detecting means for outputting a second signal when the tension applying member is at a position on a side that shortens the path length from the upper limit value, first drive means starts driving a first drive conveyance member when the first position detecting means outputs the second signal and the second drive transport member is in a stopped state, and first driving means stops the first driving conveyance member when the output of first position detecting means is switched from the second signal to the first signal.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a medium transport device, a medium transport method, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses a printer 1 including a platen 3 on which a recording medium 2 is placed during printing, a take-up shaft 21 that takes up the recording medium 2 after printing, a tension bar 22 that applies tension to the recording medium 2, swinging mechanisms 23R, 33R that swing the tension bar 22, a detection device that detects the position of the tension bar 22, a motor that rotates the take-up shaft 21, a calculation unit that calculates a winding diameter that is the outer diameter of the take-up shaft 21 or the outer diameter including the take-up shaft 21 and the wound recording medium 2, a setting unit that sets the winding start position of the recording medium 2 and the winding torque that rotates the take-up shaft 21 based on the winding diameter, and a drive unit that drives the motor to rotate the take-up shaft 21 when the detection device detects that the tension bar 22 has reached the winding start position. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention has been made in consideration of the problem that the accuracy of transporting a long medium deteriorates when the tension of the medium changes during transport, and aims to provide a medium transport device capable of transporting with high accuracy. [Means for solving the problem]

[0004] The present invention relates to a medium transport device including a first drive transport member that feeds out a long medium, a first drive means that drives the first drive transport member, a second drive transport member that transports the medium fed out by the first drive transport member, a second drive means that drives the second drive transport member, a tension applying member that is movable in a direction intersecting a medium transport path between the first drive transport member and the second drive transport member and applies tension to the medium, and a position detection means that detects the position of the tension applying member, wherein the position detection means detects the position of the tension applying member when the tension applying member moves along the medium transport path. a first position detection means for outputting a first signal when the tension applying member is at a position indicating an upper limit of a path length of a path and for outputting a second signal when the tension applying member is at a position that shortens the path length from the upper limit, and when the first position detection means outputs the second signal and the second driving and conveying member is in a stopped state, the first driving means starts driving the first driving and conveying member, and when the output of the first position detection means switches from the second signal to the first signal, the first driving means stops the first driving and conveying member. and the position detection means has a second position detection means which outputs a third signal when the tension applying member is at a position indicating a lower limit value of the path length of the medium transport path, and outputs a fourth signal when the tension applying member is at a position that lengthens the path length from the lower limit value, and during a period in which the second drive transport member is driven, when the output of the second position detection means switches from the fourth signal to the third signal, the first drive means starts driving the first drive transport member, and when the output of the first position detection means switches from the second signal to the first signal, the first drive means stops the first drive transport member; It is characterized by: Effect of the Invention

[0005] According to the present invention, it is possible to provide a medium transport device capable of transporting a long medium with high accuracy. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic configuration diagram illustrating an example of a medium conveying device of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] 4 is a control timing chart of the delivery rollers and the transport rollers. [Diagram 5] FIG. 1 is a diagram showing an overall configuration of an example of an image forming apparatus. [Figure 6] System block diagram. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] An embodiment of the present invention will be described with reference to the drawings.

[0008] FIG. 1 is a schematic diagram of a paper transport device as an example of a medium transport device.

[0009] The paper transport device 1 mainly includes a delivery roller 11, a delivery drive motor 12, a tension roller 14, a platen 16, a transport roller 17, a transport drive motor 18, a winding roller 21, a winding drive motor 22, and a control unit 23.

[0010] The control unit 23 controls the overall operation of the paper transport device 1. The control unit 23 is not necessarily provided in the paper transport device 1. For example, the control unit 23 may be provided on the side of a device that is used in conjunction with the paper transport device 1. Here, the delivery roller 11 is an example of a first drive transport member, and the delivery drive motor 12 is an example of a first drive means. Furthermore, the transport roller 17 is an example of a second drive transport member, and the transport drive motor 18 is an example of a second drive means. Furthermore, the tension roller 14 is an example of a tension applying member.

[0011] A roll of paper, which is an example of a long medium, is attached to the delivery roller 11, and the delivery roller 11 rotatably holds the roll of paper. By driving the delivery roller 11 to rotate, the paper 13 moves toward the platen 16.

[0012] The feed drive motor 12 is driven to rotate under the control of the control unit 23 to drive the feed roller 11 , and the paper 13 is fed out by the rotation of the feed roller 11 .

[0013] The winding roller 21 is a roller for winding up the paper 13 that has passed over the platen 16. When the paper transport device 1 is applied to an image forming apparatus, an image forming unit such as a recording head is installed opposite the platen 16. Therefore, the winding roller 21 winds up and holds the paper 13 after processing such as image formation.

[0014] The winding drive motor 22 is driven to rotate under the control of the control unit 23 to drive the winding roller 21, and the rotation of the winding roller 21 winds up the paper 13. In this embodiment, the operation of the winding drive motor 22 is independent of the delivery drive motor 12 and the transport drive motor 18, and the paper 13 is wound around the winding roller 21 while pulling the paper 13 with an appropriate tension.

[0015] The pinch roller 19 is located upstream of the take-up roller 21 in the paper transport direction, and pinches and transports the paper 13 between the pinch roller 19 and the transport roller 17. The pinch roller 19 is configured to press against the outer circumferential surface of the transport roller 17, and the paper 13 is pinched between the pinch roller 19 and the transport roller 17 by this pressing force.

[0016] The conveying roller 17 is driven to rotate while sandwiching the paper 13 between itself and the pinch roller 19, and conveys the processed paper 13 toward the take-up roller 21. The conveying roller 17 is driven to rotate under the control of the control unit 23 in accordance with the conveyance state of the paper 13 relative to the platen 16.

[0017] When a recording head that ejects liquid ink is disposed opposite the platen 16, the transport roller 17 stops rotating while the recording head ejects liquid ink, maintaining the state of the paper 13 suitable for image formation. At this time, the pinch roller 19 holds the paper 13 by maintaining a pressing force against the transport roller 17, and fixes the paper 13 so that it does not move while liquid is being applied to the paper 13.

[0018] The transport drive motor 18 is driven to rotate under the control of the control unit 23 to drive the transport roller 17 , and the transport roller 17 is driven to rotate to transport the paper 13 towards the take-up roller 21 .

[0019] The transport guide 15 is located upstream of the platen 16 in the paper transport direction and guides the transport of the paper 13 to the platen 16. In addition, the guide roller 20 is located between the transport roller 17 and the winding roller 21 and guides the transport of the paper 13 to the winding roller 21.

[0020] The platen 16 is a surface member for maintaining the transport position of the paper 13, and has a transport surface that constitutes the opposing surface facing the image forming unit. The transport surface of the platen 16 has air holes, and is configured to temporarily adsorb the paper 13 positioned on the transport surface to the transport surface by the operation of a vacuum pump (not shown) arranged on the opposite surface to the transport surface.

[0021] The tension roller 14 is movable in a direction intersecting the transport path of the paper 13 in order to apply tension to the paper 13. That is, the tension roller 14 is capable of being displaced to either the side that lengthens the path length of the transport path of the paper 13 (in the direction of the arrow a) or the side that shortens the path length (in the direction of the arrow b). The tension roller 14 will be described in detail below.

[0022] FIG. 2 is a configuration diagram of a tension applying device including a tension roller.

[0023] The tension applying device 30 mainly comprises a bracket 31, a guide rail 32, a slider 33, a tension roller 14, position sensors 34 and 35, and an index plunger 36.

[0024] Bracket 31 is a flat plate-shaped member. Bracket 31 supports pivot shaft 37, guide rail 32, slider 33, tension roller 14, and position sensors 34 and 35. Bracket 31 is attached to a fixed member such as an inner wall of the frame of paper transport device 1. The fixed member such as the frame of paper transport device 1 rotatably supports pivot shaft 37 fixed to bracket 31. In other words, bracket 31 is provided rotatably with respect to a fixed member such as the frame of paper transport device 1 via pivot shaft 37.

[0025] The bracket 31 has a through hole 38 and an elongated hole 39. The through hole 38 and the elongated hole 39 penetrate the bracket 31 in the thickness direction. When the bracket 31 rotates, the through hole 38 communicates with one of a plurality of positioning holes 40 provided in a fixed member such as a frame of the paper transport device 1. The elongated hole 39 extends in an arc shape centered on the rotation axis 37. In this embodiment, a configuration in which the positioning holes 40 are provided at angles between 0 degrees and 90 degrees in 5 degree increments is exemplified. This angle is set to an optimal value based on the rigidity of the medium to be transported, etc.

[0026] Then, by inserting index plunger 36 into communicating positioning hole 40 and through hole 38, bracket 31 is fixed at a predetermined rotation angle. Furthermore, bracket 31 is doubly fixed by screwing bolt 41 inserted into elongated hole 39 into a bolt hole provided in a fixing member such as the frame of paper transport device 1. Fixation through elongated hole 39 is not essential, and fixation through through hole 38 alone is also acceptable. As described above, bracket 31, rotation shaft 37, index plunger 36 and bolt 41 constitute an angle adjustment mechanism.

[0027] The guide rail 32 is a rod-shaped member that extends linearly. The guide rail 32 is fixed to the bracket 31 so as to be inclined downward toward the paper 13. The inclination angle of the guide rail 32 with respect to the horizontal direction changes as the bracket 31 rotates around the rotation shaft 37.

[0028] The guide rail 32 also supports a slider 33. The slider 33 slides along the guide rail 32. More specifically, the slider 33 descends diagonally downward (i.e., toward the paper 13) due to its own weight, and rises diagonally upward due to the reaction force it receives from the paper 13. The slider 33 is a rigid body having a weight according to the tension applied to the paper 13.

[0029] The tension roller 14 is fixed to the slider 33. The tension roller 14 is a rod-shaped member that extends in the width direction of the paper 13. The longitudinal dimension of the tension roller 14 is set to a length that contacts the entire width of the paper 13. Then, as the slider 33 descends under its own weight, the outer circumferential surface of the tension roller 14 comes into pressure contact with the paper 13.

[0030] That is, tension roller 14 presses paper 13 in the downward direction of slider 33 while contacting paper 13 in the width direction. This pressing force applies a predetermined tension to paper 13. In addition, pivot shaft 37 is disposed in a position that is coaxial with tension roller 14 when slider 33 is at the bottom end position.

[0031] The slider 33 holds a metallic detectable member 42. A position sensor 34 is disposed at a position facing the detectable member 42 when the slider 33 is at the lower end position. A position sensor 35 is disposed at a position facing the detectable member 42 when the slider 33 is at the upper end position. The position sensors 34 and 35 output a detection signal to the control unit 23 when the detectable member 42 approaches.

[0032] That is, the position sensors 34 and 35 detect the position of the slider 33. More specifically, the position sensor 34 detects that the slider 33 has reached the bottom end position, and the position sensor 35 detects that the slider 33 has reached the top end position. Note that the position sensors 34 and 35 are not limited to proximity sensors. For example, they may be optical sensors that detect reflected light or transmitted light, or contact sensors such as limit switches that detect the position of the slider 33 by contacting a part of the detected member 42. Also, a position sensor that can specify an absolute position may be used.

[0033] Figure 3 is an explanatory diagram of the operation of the tension roller. Figure 3(a) shows the tension roller 14 at the bottom dead center, Figure 3(b) shows the tension roller 14 within the detection range of the position sensor 34, and Figure 3(c) shows the tension roller 14 within the detection range of the position sensor 35.

[0034] When the paper 13 is loaded, for example, the slider 33 is initially lowered to the lower end position of the guide rail 32 as shown in FIG. 3(a), and the tension roller 14 is at the bottom dead point.

[0035] When the transport of the paper 13 begins, the tension of the paper 13 acts in a direction lifting the tension roller 14. As a result, the slider 33 moves diagonally upward along the guide rail 32 via the tension roller 14, as shown in FIG.

[0036] The position sensor 34 is provided at a position indicating the upper limit of the transport path length of the paper 13. In other words, if the path length becomes longer than this, the paper 13 will become too loose, causing problems with transport, such as the paper 13 flapping during transport. For this reason, the position sensor 34 is provided at a position indicating the upper limit of the transport path length of the paper 13, so as to regulate the allowable amount of slack in the paper 13.

[0037] When tension roller 14 is in a position indicating the upper limit of the path length of the transport path for paper 13, i.e., when detectable member 42 provided on slider 33 faces position sensor 34, position sensor 34 outputs an ON signal. When tension roller 14 is in a position on the side that shortens the aforementioned path length from the upper limit (the direction of arrow b in FIG. 3(b)), position sensor 34 outputs an OFF signal. Here, position sensor 34 is an example of a first position detection means, the ON signal output by position sensor 34 is an example of a first signal, and the OFF signal output by position sensor 34 is an example of a second signal.

[0038] As the paper 13 is transported so as to reduce its slack, the tension in the paper 13 gradually increases, and this tension acts in a direction that further lifts the tension roller 14. As a result, the slider 33 moves further diagonally upward along the guide rail 32 via the tension roller 14, as shown in FIG. 3(c).

[0039] The position sensor 35 is provided at a position indicating the lower limit of the transport path length of the paper 13. In other words, if the path length becomes shorter than this, the paper 13 will become too taut, which will cause problems with transport, such as the paper 13 breaking during transport. For this reason, the position sensor 35 is provided at a position indicating the lower limit of the transport path length of the paper 13, so as to regulate the allowable amount of tension of the paper 13.

[0040] When tension roller 14 is in a position indicating the lower limit of the path length of the transport path for paper 13, i.e., when detected member 42 provided on slider 33 faces position sensor 35, position sensor 35 outputs an ON signal. When tension roller 14 is in a position on the side that lengthens the path length from the lower limit (the direction of arrow a in FIG. 3(c)), position sensor 35 outputs an OFF signal. Here, position sensor 35 is an example of a second position detection means, the ON signal output by position sensor 35 is an example of a third signal, and the OFF signal output by position sensor 35 is an example of a fourth signal. It is.

[0041] As described above, tension roller 14 is capable of reciprocating movement between position sensor 34 and position sensor 35, and adjusts the tension applied to paper 13 within an appropriate range.

[0042] Figure 4 is a control timing chart for the feed rollers and the transport rollers. Figure 4(a) is a timing chart when the paper is continuously fed, and Figure 4(b) is a timing chart when the paper is not continuously fed.

[0043] The continuous feed shown in FIG. 4(a) is used when loading paper into paper transport device 1, when processing such as image formation on the paper is completed, and when the paper is to be wound up.

[0044] During continuous feeding, the rotation of the delivery roller 11 is started when the output of the position sensor 35 switches from an OFF signal to an ON signal while the transport roller 17 is rotating, i.e., when the path length of the transport path for the paper 13 reaches a lower limit and the tension of the paper 13 increases. The delivery roller 11 rotates until the output of the position sensor 34 changes from an OFF signal to an ON signal, and stops when the output of the position sensor 34 changes from an OFF signal to an ON signal.

[0045] 4(b) is used when performing processes such as image formation on paper. In this case, when the output of the position sensor 34 is an OFF signal and the transport roller 17 is stopped, the rotation of the feed roller 11 is started. The feed roller 11 rotates until the output of the position sensor 34 changes from an OFF signal to an ON signal, and stops the feed roller 11 when the output of the position sensor 34 changes from an OFF signal to an ON signal.

[0046] 4(b), the feed roller 11 and the transport roller 17 are not rotated at the same time. In this way, during processing such as image formation, only the position sensor 34 is used to alternately move the transport roller 17 and the feed roller 11, and the paper 13 is frequently sent out, thereby suppressing tension fluctuations and improving transport accuracy and image quality.

[0047] To perform this control, the output of the position sensor 34 must be an ON signal when no image is being formed. To achieve this, the output of the position sensor 34 must be an ON signal in both the state of FIG. 3(a) and the state of FIG. 3(b).

[0048] Therefore, the detected member 42 has a detected surface 42a that straddles a position indicating the upper limit of the paper path length (Figure 3(b)) and the bottom dead point of the tension roller 14 (Figure 3(a)), which is located on the side that makes the paper path length even longer than the position of Figure 3(b).

[0049] By configuring the detected surface 42a as described above, the position sensor 34 can output an ON signal both when the tension roller 14 is at the bottom dead center position and when the tension roller 14 is in a position where tension is applied to the paper 13. This also makes it possible to form a buffer in the detection range of the position sensor 34, which can prevent chattering when the paper 13 is being fed out.

[0050] As described above, in this embodiment, the paper transport device 1 includes the feed roller 11 that feeds out the long paper 13, the feed drive motor 12 that drives the feed roller 11, the transport roller 17 that transports the paper 13 fed out by the feed roller 11, the transport drive motor 18 that drives the transport roller 17, the tension roller 14 that is movable in a direction intersecting the paper transport path between the feed roller 11 and the transport roller 17 (arrows a and b in FIG. 1 ) and applies tension to the paper 13, and a position detection means that detects the position of the tension roller 14. The position detection means detects the position of the tension roller 14 when the tension roller 14 moves in a direction intersecting the paper transport path. The tension roller 14 has a position sensor 34 which outputs a first signal (on signal) when the tension roller 14 is in a position indicating the upper limit of the path length (the state of FIG. 3(b)), and outputs a second signal (off signal) when the tension roller 14 is in a position on the side that shortens the path length from the upper limit (the side of the arrow b in FIG. 1). When the position sensor 34 outputs the second signal and the conveying roller 17 is at a stop, the delivery drive motor 12 starts driving the delivery roller 11, and when the output of the position sensor 34 switches from the second signal (off signal) to the first signal (on signal), the delivery drive motor 12 stops the delivery roller 11.

[0051] This makes it possible to provide a paper transport device capable of transporting the paper 13 with high accuracy.

[0052] As described above, the position detection means has a position sensor 35 which outputs a third signal (on signal) when the tension roller 14 is in a position indicating the lower limit of the path length of the paper transport path (the state of FIG. 3(c)), and outputs a fourth signal (off signal) when the tension roller 14 is in a position on the side that lengthens the path length from the lower limit (the side of arrow a in FIG. 1). During the period when the transport roller 17 is driving, when the output of the position sensor 35 switches from the fourth signal (off signal) to the third signal (on signal), the feed drive motor 12 starts driving the feed roller 11, and when the output of the position sensor 34 switches from the second signal (off signal) to the first signal (on signal), the feed drive motor 12 stops the feed roller 11.

[0053] This allows high speed transport while maintaining appropriate paper tension for tasks such as continuous feeding that do not require high precision transport.

[0054] As described above, a detectable member 42 capable of facing position sensors 34, 35 is provided near tension roller 14, and detectable member 42 has a detectable surface 42a that straddles a position indicating the upper limit value of the path length (the state of FIG. 3(b)) and the bottom dead center (the state of FIG. 3(a)) of tension roller 14, which is provided on the side where the path length is further longer than the position indicating the upper limit value (the side of arrow a in FIG. 1).

[0055] This allows the position sensor 34 to detect two states (positions) with one sensor: when the tension roller 14 is at the bottom dead center position, and when the paper 13 is in a position where tension is applied.

[0056] In the above description, the first and third signals are ON signals output by the position sensors, and the second and fourth signals are OFF signals output by the position sensors, but this is not limited to this. The relationship between the ON and OFF signals may be reversed.

[0057] FIG. 5 is a diagram showing the overall configuration of an inkjet recording apparatus as an example of an image forming apparatus according to the present invention.

[0058] The inkjet recording apparatus 100 includes the paper transport device 1, the stage unit 2, the gantry unit 3, the carriage 4, the recording head 5, and the gantry drive mechanism 6, which have already been described.

[0059] The stage unit 2 constitutes a medium placement unit that has a placement surface on which a medium is placed. The stage unit 2 does not have a configuration for scanning the medium. Therefore, when the medium is placed on the placement surface, the image formation process is performed by scanning the recording head 5 over the medium.

[0060] The recording head 5 moves (scans) two-dimensionally in a plane direction parallel to the placement surface by a gantry mechanism (gantry unit 3 and gantry drive mechanism 6) and a carriage 4. The recording head 5, the carriage 4, and the gantry mechanism constitute an image forming mechanism.

[0061] The inkjet recording apparatus 100 is configured such that the paper transport device 1 can be connected to and separated from a portion of the stage section 2, and can flexibly handle media ranging from soft media to rigid media according to the user's needs.

[0062] When forming an image (printing) using paper 13 (roll paper) as already explained, the paper transport device 1 is connected to the end of the stage section 2. The carriage 4 and gantry section 3 carrying the recording head 5 are moved in the direction of arrow A, and the carriage 4 and gantry section 3 are fixed to the end of the stage section 2 (corresponding to the position facing the platen 16). Then, the recording head 5 is moved in the scanning direction relative to the paper 13 that has come onto the platen 16, and the recording head 5 forms an image on the paper 13.

[0063] FIG. 6 is a system block diagram of the image forming apparatus exemplified in FIG.

[0064] The paper transporting device 1 is connected to the image forming apparatus 100 via a control unit 23. The control unit 23 may be provided in the paper transporting device 1 or in the image forming apparatus 1.

[0065] The paper transport device 1 includes a position sensor 34, a position sensor 35, a delivery drive motor 12, a transport drive motor 18, and the like.

[0066] The position sensor 34 outputs (transmits) a first signal and a second signal to the control unit 23 in accordance with the position of the tension roller 14. The position sensor 35 outputs a third signal and a fourth signal to the control unit 23 in accordance with the position of the tension roller 14.

[0067] The delivery drive motor 12 receives a command from the control unit 23 and rotates or stops the delivery rollers 11. The transport drive motor 18 receives a command from the control unit 23 and rotates or stops the transport rollers 17.

[0068] The control unit 23 controls the operation of the entire system including the paper transport device 1 and the image forming device 100. The control unit 23 has an arithmetic processing unit and a storage device, and realizes each of these functional units by the arithmetic processing unit executing a program previously recorded in the storage device.

[0069] The image forming apparatus 100 receives a command from the control unit 23 and performs a desired image formation on the medium being transported by the paper transport device 1. In addition, the image forming apparatus 100 transmits information indicating the state of the apparatus to the control unit 23.

[0070] The above description is merely an example, and the present invention provides unique effects for each of the following aspects.

[0071] (Aspect 1) A first aspect is a medium transport device (e.g., paper transport device 1) including a first drive transport member (e.g., feed roller 11) that feeds out a long medium (e.g., paper 13), a first drive means (e.g., feed drive motor 12) that drives the first drive transport member, a second drive transport member (e.g., transport roller 17) that transports the medium fed out by the first drive transport member, a second drive means (e.g., transport drive motor 18) that drives the second drive transport member, a tension applying member (e.g., tension roller 14) that is movable in a direction intersecting a medium transport path between the first drive transport member and the second drive transport member (e.g., the direction of arrow a and the direction of arrow b in FIG. 1 ) and applies tension to the medium, and a position detection means that detects the position of the tension applying member. The device has a first position detection means (e.g., position sensor 34) that outputs a first signal (e.g., an on signal of position sensor 34) when the force applying member is in a position indicating the upper limit of the path length of the medium transport path (e.g., the state in Figure 3(b)), and outputs a second signal (e.g., an off signal of position sensor 34) when the tension applying member is in a position that shortens the path length from the upper limit (e.g., the side of arrow b in Figure 1), and is characterized in that when the first position detection means outputs the second signal and the second drive transport member is in a stopped state, the first drive means starts driving the first drive transport member, and when the output of the first position detection means switches from the second signal to the first signal, the first drive means stops the first drive transport member.

[0072] According to the first aspect, it is possible to provide a medium conveying device capable of conveying a long medium with high accuracy.

[0073] (Aspect 2) In a second aspect of the first aspect, the position detection means includes a second position detection means (e.g., a position sensor 35) that outputs a third signal (e.g., an ON signal of a position sensor 35) when the tension applying member (e.g., a tension roller 14) is in a position indicating a lower limit value of the path length of the medium transport path (e.g., the state of FIG. 3(c)), and outputs a fourth signal (e.g., an OFF signal of the position sensor 35) when the tension applying member is in a position on the side that lengthens the path length from the lower limit value (e.g., the side of the arrow a in FIG. 1), and the second drive transport section During a period in which the material (e.g., conveying roller 17) is being driven, when the output of the second position detection means switches from the fourth signal to the third signal, the first driving means (e.g., feed drive motor 12) starts driving the first driving conveying member (e.g., feed roller 11), and when the output of the first position detection means (e.g., position sensor 34) switches from the second signal to the first signal, the first driving means stops the first driving conveying member (e.g., feed roller 11).

[0074] According to the second aspect, in a transport operation that does not require highly accurate transport, the medium can be transported at high speed while maintaining an appropriate tension.

[0075] (Aspect 3) A third aspect of the present invention is characterized in that, in the first or second aspect, a detectable member (e.g., detectable member 42) capable of facing the position detection means (e.g., position sensors 34, 35) is provided near the tensioning member (e.g., tension roller 14), and the detectable member has a detectable surface (e.g., detectable surface 42a) that straddles a position indicating an upper limit value of the path length (e.g., the state of FIG. 3(b)) and the bottom dead center (e.g., the state of FIG. 3(a)) of the tensioning member provided on the side where the path length is further lengthened (e.g., the side of arrow a in FIG. 1) relative to the position indicating the upper limit value.

[0076] According to the third aspect, a single position detection means can detect two states: a state in which the tension applying member is at the bottom dead center position, and a state in which tension is being applied to the medium. [Explanation of symbols]

[0077] 1 Paper transport device 11 Delivery roller (first driving conveying member) 12 Delivery drive motor (first drive means) 13 Paper (media) 14 Tension roller (tensioning member) 15 Transport guide 16 Platen 17 Conveying roller (second driving conveying member) 18 Transport drive motor (second drive means) 19 Pinch roller 20 Guide roller 21 Winding roller 22 Winding drive motor 23 Control Unit [Prior art documents] [Patent documents]

[0078] [Patent Document 1] JP 2018-012599 A

Claims

1. A first driving conveying member that conveys the long medium; a first driving means for driving the first driving conveying member; a second driving transport member that transports the medium sent out by the first driving transport member; a second driving means for driving the second driving conveying member; a tension applying member movable in a direction intersecting a medium transport path between the first drive transport member and the second drive transport member, and applying tension to the medium; a position detection unit for detecting a position of the tension applying member, the position detection means outputs a first signal when the tension applying member is at a position indicating an upper limit value of a path length of the medium transport path; a first position detection means for outputting a second signal when the tension applying member is at a position on the side that shortens the path length from the upper limit value, When the first position detection means outputs the second signal and the second driving and conveying member is in a stopped state, the first driving means starts driving the first driving and conveying member, When an output of the first position detection means is switched from the second signal to the first signal, the first driving means stops the first driving and conveying member; and the position detection means outputs a third signal when the tension applying member is at a position indicating a lower limit value of the path length of the medium transport path; a second position detection means for outputting a fourth signal when the tension applying member is at a position that increases the path length from the lower limit value, When an output of the second position detection means is switched from the fourth signal to the third signal during a period in which the second driving conveyance member is being driven, the first driving means starts driving the first driving conveyance member, when an output of the first position detection means is switched from the second signal to the first signal, the first driving means stops the first driving conveyance member; A medium transport device comprising:

2. A detectable member that moves together with the tensioning member and is capable of facing the position detecting means is provided near the tensioning member, 2. The medium transport device according to claim 1, characterized in that the detectable member has a detectable surface that extends from a point facing the first position detection means when the tensioning member is in a position indicating an upper limit value of the path length to a point facing the first position detection means when the tensioning member is in a position at the bottom dead center of the tensioning member, which is a position that makes the path length even longer than the position indicating the upper limit value.

3. A first driving conveying member that conveys the long medium; a first driving means for driving the first driving conveying member; a second driving transport member that transports the medium sent out by the first driving transport member; a second driving means for driving the second driving conveying member; a tension applying member movable in a direction intersecting a medium transport path between the first drive transport member and the second drive transport member, and applying tension to the medium; A medium conveying method for a medium conveying device including a position detection unit that detects a position of the tension applying member, the position detection means outputs a first signal when the tension applying member is at a position indicating an upper limit value of a path length of the medium transport path; a first position detection means for outputting a second signal when the tension applying member is at a position on the side that shortens the path length from the upper limit value, when the first position detection means outputs the second signal and the second driving and conveying member is in a stopped state, the first driving means starts driving the first driving and conveying member; When the output of the first position detection means transitions from the second signal to the first signal in accordance with the driving of the first driving and conveying member, the first driving means stops the first driving and conveying member; and the position detection means outputs a third signal when the tension applying member is at a position indicating a lower limit value of the path length of the medium transport path; a second position detection means for outputting a fourth signal when the tension applying member is at a position that increases the path length from the lower limit value, When the output of the second position detection means changes from the fourth signal to the third signal during a period in which the second driving and conveying member is being driven, the first driving means starts driving the first driving and conveying member, when an output of the first position detection means transitions from the second signal to the first signal in accordance with the driving of the first driving conveyance member, the first driving means stops the first driving conveyance member; A medium transport method comprising:

4. 3. An image forming apparatus comprising the medium transport device according to claim 1.

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