Recording device

Abstract

Provided is a recording device enabled for appropriately maintaining tension imparted to a recording medium even if switchback takes place.　In a textile printing machine 1, a source spooling unit 3 sends a printing medium M to a platen 21. An upstream tension bar 5 comes into contact with the printing medium M sent from the source spooling unit 3, and as a result of the upstream tension bar rocking under its own weight in response to slack in the printing medium M, applies tension to the printing medium M. A detection unit detects the position of the upstream tension bar 5. A conveyance roller 8 is disposed downstream of the upstream tension bar 5 in a conveyance direction, and is enabled for conveying the printing medium M in the conveyance direction and in an opposite direction of the conveyance direction. The action of conveying in the opposite direction of the conveyance direction is "switchback." On the basis of results of detection by the detection unit, a CPU rotates a shaft 31A of the source spooling unit 3 in a direction opposite a direction in which the printing-medium M is sent.

Description

Recording device

[0001] The present invention relates to a recording device.

[0002] The printer device disclosed in Patent Document 1 is equipped with a tension bar. The print medium is fed from the main winding side, which supports the print medium wound in a roll. The tension bar oscillates to apply tension to the print medium fed from the main winding side. A guide bar is located downstream of the tension bar. The guide bar changes the transport angle of the print medium.

[0003] Patent No. 5081602

[0004] In the printing device described above, there are cases where a so-called switchback is performed after printing is completed, in which the print medium is transported in the opposite direction to the feed direction. When a switchback is performed, if the switchback amount exceeds the allowable swing amount of the tension bar, slack will occur on the main winding side of the print medium, which can cause problems with the tension applied to the print medium during the next printing.

[0005] An object of the present invention is to provide a recording device that can appropriately maintain tension applied to a recording medium even when a switchback occurs.

[0006] The recording device of claim 1 includes a platen that supports a recording medium, a recording head that ejects a recording agent onto the recording medium supported on the platen, a main winding unit that feeds the recording medium from a roll of the recording medium toward the platen, a tension bar that contacts the recording medium fed from the main winding unit and applies tension by swinging in response to slack in the recording medium, a detection unit that detects the position of the tension bar, a transport roller positioned downstream of the tension bar in the recording medium transport direction and capable of transporting the recording medium in the transport direction and in the opposite direction to the transport direction, and a control unit that drives the main winding unit in the opposite direction to the recording medium feed direction based on the detection result of the detection unit. When a recording medium is transported in the opposite direction to the transport direction, a so-called "switchback," the tension applied to the recording medium is released. At this time, the tension bar swings in the direction of gravity and changes position, and the main winding unit is driven in the opposite direction based on the position of the tension bar to wind up unnecessary slack in the recording medium. This prevents tension problems from occurring when recording on the next recording medium. Therefore, even when the recording device is switched back, the tension applied to the recording medium can be appropriately maintained.

[0007] The control unit of the recording device of claim 2 may drive the head winding unit in the opposite direction when the detection unit detects that the tension bar is at the lower limit of its swing range. Since the head winding unit is driven in the opposite direction when the tension bar reaches the lower limit of its swing range, there is no need to drive the head winding unit if, for example, the switchback amount is small and the tension bar does not swing to the lower limit. In this case, the recording device can take up unnecessary slack in the recording medium by swinging the tension bar alone.

[0008] The transport roller of the recording device of claim 3 may be located downstream of the recording head in the transport direction. Even if the transport roller is located downstream of the recording head, the recording device can reduce slack caused by switchback, thereby preventing any impact on the recording quality of the recording medium. The recording device can perform good recording with the recording head without slack, even on soft recording media, for example.

[0009] The lower limit position of the tension bar of the recording device of claim 4 may be above the original winding portion. Therefore, the recording device can automatically move the tension bar upward as the tension of the recording medium increases.

[0010] A recording device according to claim 5 further includes a roller with a torque limiter disposed between the platen and the tension bar in the transport path of the recording medium, the tension bar swinging about its rotation axis, and the roller may be disposed outside the rotation locus of the tension bar about its rotation axis. This allows the recording device to swing the tension bar against its own weight in accordance with the tension applied when the recording medium is transported.

[0011] The control unit of the recording device of claim 6 may drive the master winding unit in the feed direction when the detection unit detects that the tension bar is at the upper limit position of the swing range, thereby allowing the recording medium to be kept in a state where an appropriate tension is applied.

[0012] A recording device according to a seventh aspect of the present invention may include an arm that supports the tension bar so that it can swing freely around a rotation axis, the detection unit having a first photointerrupter and a second photointerrupter, and the arm may be provided with a first shielding portion that is detected by the first photointerrupter when the tension bar is at the upper limit position, and a second shielding portion that is detected by the second photointerrupter when the tension bar is at the lower limit position. Thus, the recording device can accurately detect two positions of the tension bar using two photointerrupters.

[0013] FIG. 1 is a simplified diagram showing the configuration of the textile printing machine 1 (during normal transport); FIG. 2 is a diagram showing the structure around the support beam 15; FIG. 3 is a diagram showing the structure around the support beam 15 (upstream tension bar 5: upper limit position); FIG. 4 is a diagram showing the structure around the support beam 15 (upstream tension bar 5: lower limit position); FIG. 5 is a cross-sectional view of the registration roller 6; FIG. 6 is a simplified diagram showing the configuration of the textile printing machine 1 (during switchback); FIG. 7 is a block diagram showing the electrical configuration of the textile printing machine 1; FIG. 8 is a flowchart of the feed motor control process; FIG. 9 is a flowchart of the master winding motor control process.

[0014] An embodiment of the present invention will be described. In the following description, various directions such as front and rear, up and down, left and right, as indicated by arrows in the drawings, will be used. The right side, left side, upper side, lower side, front side of the paper, and rear side of the paper in Fig. 1 correspond to the rear side, front side, upper side, lower side, right side, and left side of the textile printing machine 1.

[0015] The configuration of a textile printing machine 1 will be described with reference to FIG. 1. The textile printing machine 1 shown in FIG. 1 is a printing device that is elongated in the left-right direction. The textile printing machine 1 prints characters, figures, and the like on a printing surface M1 of a sheet-like printing medium M, such as cloth, woven fabric, paper, PVC sheet, tarpaulin, or polyester film. The textile printing machine 1 includes a printing unit 2, a master winding unit 3, and a winding unit 4. The printing unit 2 is provided at the top of the textile printing machine 1 and includes a platen 21 and a print head 22. The platen 21 extends in the front-to-rear and left-to-right directions and supports the printing medium M from below. The print head 22 is supported above the platen 21 and faces the printing surface M1 of the printing medium M across a predetermined gap. The print head 22 is a piezo-type printing device that performs printing by ejecting ink onto the printing surface M1 of the printing medium M.

[0016] The master winding unit 3 is provided at approximately the middle position on the rear side of the printing machine 1. The master winding unit 3 includes a shaft 31A, a pair of left and right holders 31 (only the right holder 31 is shown in FIG. 1), and a master winding motor 32 (see FIG. 7). The shaft 31A extends in the left-right direction and is supported approximately horizontally by a pair of left and right support beams 15 (only the right support beam 15 is shown in FIGS. 1 to 4) provided on both the left and right sides of the middle position of the printing machine 1. The shaft 31A supports a master winding roll 100. The master winding roll 100 is a roll of printing medium M in an unprocessed state (before printing processing) wound around a cardboard tube (not shown). The printing medium M is wound around the cardboard tube with the printing surface M1 facing outward.

[0017] The pair of left and right holders 31 are attached to a shaft 31A and support both ends of a paper tube inserted into the shaft 31A, thereby supporting the master roll 100. Therefore, the master roll 100 rotates integrally with the shaft 31A. A master winding motor 32 drives the shaft 31A to rotate. The master winding motor 32 rotates the shaft 31A in the A1 direction, thereby unwinding the printing medium M from the master roll 100 supported by the shaft 31A toward the printing unit 2.

[0018] The winding unit 4 is provided at a lower position on the front side of the textile printing machine 1. The winding unit 4 includes a shaft 41A, a pair of left and right holders 41, and a winding motor 42 (see FIG. 7). The shaft 41A extends left and right and is supported substantially horizontally by a pair of left and right support beams 16 (only the right support beam 16 is shown in FIG. 1) provided on both the left and right sides of the lower position of the textile printing machine 1. The shaft 41A supports a paper tube (not shown). The pair of left and right holders 41 are attached to the shaft 41A and support the paper tube from both the left and right sides. Therefore, the paper tube rotates integrally with the shaft 41A. The winding motor drives the shaft 41A to rotate in the D1 direction. Therefore, after printing by the print head 22 is completed, the winding unit 4 winds the printing medium M transported in the F1 direction onto the paper tube with the printed surface M1 facing outward.

[0019] The transport path for the printing medium M extends from the master winding unit 3 via the printing unit 2 to the winding unit 4, and is a generally U-shaped path that opens downward in a side view. Arranged in this transport path from the master winding unit 3 to the printing unit 2 are, in order from the upstream side, an upstream tension bar 5, registration rollers 6, and upstream intermediate rollers 7. Arranged in this transport path from the printing unit 2 to the winding unit 4 are, in order from the upstream side, transport rollers 8, downstream intermediate rollers 9, and downstream tension bar 10.

[0020] The upstream tension bar 5 is positioned behind and diagonally above the shaft 31A of the master winding unit 3. The upstream tension bar 5 extends in the left-right direction. The upstream tension bar 5 comes into contact with the back surface M2 of the printing medium M. The upstream tension bar 5 is supported by a swing arm 25, which will be described later, and swings up and down around a rotation shaft 26 under its own weight in accordance with the tension of the printing medium M. The structure that swings the upstream tension bar 5 will be described later.

[0021] The registration rollers 6 are positioned diagonally above and in front of the upstream tension bar 5. The registration rollers 6 extend in the left-right direction. The registration rollers 6 come into contact with the printing surface M1 of the print medium M. A torque limiter 66 (see FIGS. 2 and 5), which will be described later, is attached to the rotation shaft 61 of the registration rollers 6, and the registration rollers 6 rotate together with the print medium M in the B1 direction with a predetermined torque.

[0022] The upstream intermediate roller 7 is positioned slightly forward of directly above the registration roller 6, between a first imaginary line L1 and a second imaginary line L2. The first imaginary line L1 is a straight line that passes vertically through the rotation shaft 61 of the registration roller 6. The second imaginary line L2 is parallel to the first imaginary line L1 and is a tangent to the front outer peripheral surface of the registration roller 6 that contacts the printing surface M1 of the printing medium M. The upstream intermediate roller 7 extends in the left-right direction and has a smaller diameter than the registration roller 6. The upstream intermediate roller 7 contacts the back surface M2 of the printing medium M. By positioning the upstream intermediate roller 7 in the above position, the textile printing machine 1 can position the printing medium M so that it is wrapped around the front outer peripheral surface of the registration roller 6, thereby ensuring a sufficient contact area of ​​the printing medium M with the registration roller 6.

[0023] The transport roller 8 is provided in front of the platen 21, at the upper front end of the textile printing machine 1. The transport roller 8 extends in the left-right direction and is rotationally driven by a feed motor 81 (see FIG. 7 ). The transport roller 8 contacts the back surface M2 of the printing medium M and, by rotating forward in the direction C1, transports the printing medium M in the direction F1 while guiding it downward toward the winding unit 4. Here, the direction from the transport roller 8 toward the winding unit 4 is the direction in which the printing medium M is pressed toward the platen 21. Therefore, the textile printing machine 1 can maintain the parallelism of the printing medium M on the platen 21 by transporting it with the transport roller 8. Furthermore, because the platen 21 does not have a mechanism for nipping the printing medium M, the printing medium M is easy to handle relative to the platen 21.

[0024] The downstream intermediate rollers 9 are disposed in the middle position of the textile printing machine 1 and below the transport rollers 8. The downstream intermediate rollers 9 extend in the left-right direction and come into contact with the printing surface M1 of the print medium M. The downstream intermediate rollers 9 guide the print medium M straight downward from the transport rollers 8.

[0025] The downstream tension bar 10 is positioned diagonally above and in front of the winding unit 4. The downstream tension bar 10 extends in the left-right direction. The downstream tension bar 10 comes into contact with the back surface M2 of the printing medium M. The downstream tension bar 10 is supported by a swing arm 27, and swings up and down around a rotation shaft 28 under its own weight in accordance with the tension of the printing medium M.

[0026] In the transport path downstream of the printing unit 2, a heater 13 is disposed between the transport roller 8 and the downstream intermediate roller 9. The heater 13 faces the printing surface M1 of the print medium M transported from the transport roller 8 toward the downstream intermediate roller 9. The heater 13 dries the printing surface M1 after printing.

[0027] The support structure of the upstream tension bar 5 will be specifically described with reference to Figures 1 and 2. A metal support beam 15 extends in the front-rear direction on the right side of the mid-stage position of the textile printing machine 1. Another metal support beam, identical in shape to the support beam 15, extends in the front-rear direction on the left side of the mid-stage position of the textile printing machine 1. The base end of a long swing arm 25 is rotatably supported on the rear end of the left face of the right support beam 15. A rotation shaft 26 protruding to the right is provided at the base end of the swing arm 25. The rotation shaft 26 is inserted from the left side into a hole 151 (see Figure 2) provided on the rear end of the support beam 15 and protrudes rightward from a right face 152 of the support beam 15. A detector 50 is attached to the rear end of the right face 152 of the support beam 15 near the rotation shaft 26. The detector 50 detects the swing position of the swing arm 25. The right end of the upstream tension bar is connected to the tip of the swing arm 25. The configuration of the detection unit 50 will be described later.

[0028] Although not shown, the base end of a swing arm having the same shape as the swing arm 25 is also rotatably supported on the inside rear end of the left support beam. The left end of the upstream tension bar 5 is connected to the tip end of the swing arm. As a result, the upstream tension bar 5 is swingably supported by the pair of left and right support beams 15 via the pair of left and right swing arms 25, and swings in an arc along a locus Q1 (see FIG. 1). The locus Q1 is an arc-shaped rotation locus centered on the rotation shaft 26, and has an upper limit position P1 and a lower limit position P2.

[0029] 1 and 2, the support structure of the downstream tension bar 10 will be specifically described. On the right side of the lower position of the textile printing machine 1, a metal support beam 16 extends in the front-rear direction. On the left side of the lower position of the textile printing machine 1, another metal support beam having the same shape as the support beam 16 extends in the front-rear direction. The base end of a swing arm 27 is rotatably supported on the inside of the support beam 16. A rotation shaft 28 that protrudes to the right is provided at the base end of the swing arm 27. The rotation shaft 28 is inserted from the left side into a hole (not shown) provided in the support beam 16, and protrudes rightward from the right surface of the support beam 16.

[0030] Although not shown, the base end of a swing arm having the same shape as the swing arm 27 is also rotatably supported on the inside of the left support beam. The left end of the downstream tension bar 10 is connected to the tip end of the swing arm. As a result, the downstream tension bar 10 is swingably supported by the pair of left and right support beams 16 via the pair of left and right swing arms 27, and swings in an arc along a trajectory Q2. The trajectory Q2 is an arc-shaped rotation trajectory centered on the rotation axis.

[0031] The configuration of the detection unit 50 will be described with reference to Figures 2 to 4. As shown in Figure 2, the detection unit 50 includes an upper limit sensor 51, a lower limit sensor 52, and shielding members 35 and 36. The upper limit sensor 51 and the lower limit sensor 52 are well-known photointerrupters. The upper limit sensor 51 detects when the upstream tension bar 5 is at its upper limit position. The lower limit sensor 52 detects when the upstream tension bar 5 is at its lower limit position.

[0032] The upper limit sensor 51 is fixed to the front side of the hole 151 on the right surface 152 of the support beam 15. The upper limit sensor 51 includes a light-emitting unit 511 and a light-receiving unit 512. The light-emitting unit 511 and the light-receiving unit 512 are aligned in the front-to-rear direction and disposed at a predetermined distance from each other. Light emitted from the light-emitting unit 511 is received by the light-receiving unit 512. When there is no obstruction between the light-emitting unit 511 and the light-receiving unit 512, the upper limit sensor 51 outputs an OFF signal. When there is obstruction between the light-emitting unit 511 and the light-receiving unit 512, the upper limit sensor 51 outputs an ON signal. Note that the conditions for outputting the OFF signal and the ON signal may be reversed.

[0033] The lower limit sensor 52 is fixed to the rear side of the hole 151 on the right surface 152 of the support beam 15, and is disposed at approximately the same height as the upper limit sensor 51. The lower limit sensor 52 also includes a light-emitting unit 521 and a light-receiving unit 522. The light-emitting unit 521 and the light-receiving unit 522 are aligned in the front-to-rear direction and disposed at a predetermined distance from each other. Light emitted from the light-emitting unit 521 is received by the light-receiving unit 522. When there is no obstruction between the light-emitting unit 521 and the light-receiving unit 522, the lower limit sensor 52 outputs an OFF signal. When there is obstruction between the light-emitting unit 521 and the light-receiving unit 522, the lower limit sensor 52 outputs an ON signal. Note that the conditions for outputting the OFF signal and the ON signal may be reversed.

[0034] The shielding members 35 and 36 are plate members bent into a substantially L-shape. The shielding members 35 and 36 are fixed by screws 29 at different inclination angles to the right end of the rotation shaft 26, which rotates integrally with the swing arm 25. The shielding member 35 is disposed on the upper limit sensor 51 side (front side), and the shielding member 36 is disposed on the lower limit sensor 52 side (rear side).

[0035] The shielding member 35 includes an arm 351 and a shielding portion 352. The arm 351 is an elongated, approximately rectangular plate, and its base end is fixed to the right end of the rotation shaft 26 with a screw 29. The shielding portion 352 bends at an approximately right angle from the tip of the arm 351 toward the support beam 15. The shielding member 36 includes an arm 361 and a shielding portion 362. The arm 361 is an elongated, approximately rectangular plate, and its base end is placed on the left side of the base end of the arm 351 of the shielding member 35, and is fixed to the right end of the rotation shaft 26 with a screw 29. The shielding portion 362 bends at an approximately right angle from the tip of the arm 351 toward the support beam 15.

[0036] As shown in Figure 2, when the upstream tension bar 5 is in the intermediate region between the upper limit position P1 and the lower limit position P2 (see Figure 1), the shielding member 35 tilts obliquely upward in front of the rotating shaft 26. At this time, the shielding portion 352 is positioned upward from between the light-emitting portion 511 and the light-receiving portion 512 of the upper limit sensor 51. The shielding member 36 tilts obliquely upward behind the rotating shaft 26. At this time, the shielding portion 362 is also positioned upward from between the light-emitting portion 521 and the light-receiving portion 522 of the lower limit sensor 52. Therefore, both the upper limit sensor 51 and the lower limit sensor 52 output OFF signals, and the detection unit 50 can detect that the upstream tension bar 5 is in the intermediate region.

[0037] As shown in FIG. 3, when the upstream tension bar 5 is at the upper limit position P1 (see FIG. 1), the shielding member 35 is approximately horizontal in front of the rotating shaft 26. At this time, the shielding portion 352 is positioned between the light-emitting portion 511 and the light-receiving portion 512 of the upper limit sensor 51. The light emitted from the light-emitting portion 511 is blocked by the shielding portion 352. Therefore, the upper limit sensor 51 outputs an ON signal. On the other hand, the shielding member 36 is tilted obliquely upward behind the rotating shaft 26. At this time, the shielding portion 362 is positioned at a position above the light-emitting portion 521 and the light-receiving portion 522 of the lower limit sensor 52. Therefore, the lower limit sensor 52 outputs an OFF signal. Therefore, the detection unit 50 can detect that the upstream tension bar 5 is at the upper limit position P1.

[0038] As shown in FIG. 4, when the upstream tension bar 5 is at the lower limit position P2 (see FIG. 1), the shielding member 36 is approximately horizontal behind the rotating shaft 26. At this time, the shielding portion 362 is positioned between the light-emitting portion 521 and the light-receiving portion 522 of the lower limit sensor 52. The light emitted from the light-emitting portion 521 is blocked by the shielding portion 362. Therefore, the lower limit sensor 52 outputs an ON signal. On the other hand, the shielding member 35 is tilted obliquely upward in front of the rotating shaft 26. At this time, the shielding portion 352 is positioned above and away from between the light-emitting portion 511 and the light-receiving portion 512 of the upper limit sensor 51. Therefore, the upper limit sensor 51 outputs an OFF signal. Therefore, the detection unit 50 can detect that the upstream tension bar 5 is at the lower limit position P2.

[0039] The support structure of the registration roller 6 will be described in detail with reference to Figures 2 and 5. As shown in Figure 2, the lower part of the support member 17 extending upward is fixed to the upper end 153 of the right support beam 15. The support member 17 is bent in a stepped manner upward and toward the left, and a support portion 171 is provided at its upper part. The support portion 171 is a plate-like member that extends in the vertical direction and faces in the horizontal direction. Although not shown, a support member is also fixed to the upper end of the left support beam, and a plate-like support portion is provided at the top of that support member. The support member and support portion on the left side are symmetrical to the support member 17 and support portion 171 on the right side.

[0040] As shown in Figure 5, the rotation shaft 61 of the registration roller 6 extends in the left-right direction, and both left and right ends thereof are inserted into holes 175 formed in the support portions 171 of the pair of left and right support members 17. Therefore, the rotation shaft 61 is rotatably supported by the pair of left and right support members 17. A torque limiter 66 is attached to the right end of the rotation shaft 61. The torque limiter 66 is fixed to the right surface of the support portion 171 of the right support member 17. When a rotational load greater than a predetermined torque is applied, the torque limiter 66 rotates while slipping, thereby transmitting tension T1 to the print medium M via the rotation shaft 61.

[0041] The registration roller 6 includes a pair of left and right fixed portions 62 (only the right fixed portion 62 is shown in FIG. 5 ), an inner cylinder 63, and an outer cylinder 64. The pair of left and right fixed portions 62 are attached to both the left and right sides of a portion of the rotating shaft 61 that is sandwiched between the pair of left and right support portions 171. The fixed portion 62 is a short-axis, approximately cylindrical shape extending in the left-right direction, and includes a flange 621 on one end side in the axial direction. The flange 621 protrudes radially outward from the fixed portion 62. The rotating shaft 61 is inserted inside the fixed portion 62. A one-way clutch 67 is attached between the right end of the rotating shaft 61 and the inner circumferential surface of the fixed portion 62.

[0042] The inner tube 63 is cylindrical and extends in the left-right direction, and accommodates the rotating shaft 61 therein. Of the pair of left and right fixing portions 62, the flange 621 of the right fixing portion 62 engages from the right with a step 631 provided on the inner periphery of the right open end of the inner tube 63, and is fixed with multiple screws 65. The flange (not shown) of the left fixing portion engages from the left with a step (not shown) provided on the inner periphery of the left open end of the inner tube 63, and is fixed with multiple screws. Therefore, the inner tube 63 is integrated with the rotating shaft 61 via the pair of left and right fixing portions 62. The inner tube 63 is inserted into the outer tube 64. The inner periphery of the outer tube 64 is fixed to the outer periphery of the inner tube 63.

[0043] As shown in Fig. 1, when the printing medium M is transported toward the platen 21, the registration roller 6 rotates in the B1 direction. When the registration roller 6 rotates in the B1 direction, the one-way clutch 67 connects the rotary shaft 61 to the registration roller 6, causing the registration roller 6 to rotate together with the rotary shaft 61. On the other hand, as shown in Fig. 6, when the printing medium M is transported in the reverse direction toward the master winding unit 3 (when a so-called switchback is performed), the registration roller 6 rotates in the B2 direction. When the registration roller 6 rotates in the B2 direction, the one-way clutch 67 separates the registration roller 6 from the rotary shaft 61, causing the registration roller 6 to rotate freely relative to the rotary shaft 61.

[0044] The electrical configuration of the printing machine 1 will be described with reference to Figure 7. The printing machine 1 includes a CPU 91, a ROM 92, and a RAM 93. The CPU 91, ROM 92, and RAM 93 are electrically connected to one another. The CPU 91 controls the overall operation of the printing machine 1 and is electrically connected to the ROM 92 and RAM 93. The ROM 92 stores various programs such as a feed motor control program and a master winding motor control program. The feed motor control program executes a feed motor control process (see Figure 8) described below. The master winding motor control program executes a master winding motor control process (see Figure 9) described below. The RAM 93 temporarily stores various data, etc.

[0045] The feed motor 81, master winding motor 32, take-up motor 42, print head 22, operation unit 45, upper limit sensor 51, and lower limit sensor 52 are electrically connected to the CPU 91. The feed motor 81, master winding motor 32, take-up motor 42, and print head 22 are each driven under the control of the CPU 91.

[0046] The operation unit 45 outputs information to the CPU 91 in response to operations by the user. The operation unit 45 is equipped with a power button 46 and a print button 47. The user can switch the power of the textile printing machine 1 on and off by operating the power button 46. The user can input a print command to the textile printing machine 1 to start printing by operating the print button 47. The upper limit sensor 51 outputs a detection signal (on / off signal) from the light receiving unit 512 to the CPU 91. The lower limit sensor 52 outputs a detection signal (on / off signal) from the light receiving unit 522 to the CPU 91. The CPU 91 detects the swing position of the upstream tension bar 5 based on the detection signals from the upper limit sensor 51 and the lower limit sensor 52, respectively.

[0047] The feed motor control process will be described with reference to Fig. 8. This process controls the drive of the feed motor 81. When the user operates the power button 46, the CPU 91 reads out a feed motor control program from the ROM 92 and executes this process.

[0048] <Normal Conveyance> The CPU 91 determines whether the print button 47 has been operated and printing has started (S11). If the print button 47 has been operated (S11: YES), the CPU 91 rotates the feed motor 81 forward (S12) and rotates the conveyance roller 8 in the C1 direction (see FIG. 1).

[0049] As shown in Figure 1, when the transport roller 8 rotates in the C1 direction, the printing medium M on the platen 21 is transported in the F1 direction along the transport path. At the same time, the printing operation by the print head 22 begins. At the start of printing, tension is applied to the printing medium M as it is transported in the F1 direction with the shaft 31A of the master winding unit 3 stopped. As the tension applied to the printing medium M increases, the upstream tension bar 5 swings upward. When the upstream tension bar 5 reaches the upper limit position P1, the shaft 31A of the master winding unit 3 rotates in the A1 direction in the master winding motor control process (see Figure 9), which will be described later, and the printing medium M is unwound from the master roll 100.

[0050] The upstream tension bar 5 comes into contact with the back surface M2 of the printing medium M and swings up and down under its own weight in accordance with the tension applied to the printing medium M. If the tension applied to the printing medium M is weak, slack occurs in the printing medium M, causing the upstream tension bar 5 to swing downward. If the tension applied to the printing medium M is strong, the upstream tension bar 5 is lifted by the printing medium M and swings upward. Therefore, the textile printing machine 1 can apply tension T2 to the printing medium M while suppressing slack in the printing medium M in the transport path upstream of the print head 22.

[0051] In the transport path upstream of the print head 22, the registration rollers 6 come into contact with the printing surface M1 of the print medium M. The registration rollers 6 are rotated in the B1 direction at a predetermined torque by the torque limiter 66, applying tension T1 to the print medium M. As a result, a tension equal to the sum of tension T1 and tension T2 is applied to the print medium M on the platen 21.

[0052] The print medium M printed by the print head 22 is transported forward on the platen 21 and then turned downward by the transport roller 8. The print medium M then passes through the downstream intermediate roller 9 and downstream tension bar 10 and is transported toward the winding unit 4. The winding motor 42 rotates forward in accordance with the rotation of the feed motor 81, so the shaft 41A and holder 41 rotate in the D1 direction. The D1 direction is the winding direction in which the print medium M is wound onto the paper tube supported by the shaft 41A. In this way, the printed print medium M is wound onto the paper tube supported by the shaft 41A with the printing surface M1 facing outward.

[0053] In the transport path downstream of the print head 22, the downstream tension bar 10 comes into contact with the back surface M2 of the print medium M and swings under its own weight in accordance with the slack of the print medium M. If the tension applied to the print medium M is weak, the downstream tension bar 10 swings downward, and if the tension applied to the print medium M is strong, the downstream tension bar 10 is lifted by the print medium M and swings upward. Therefore, the textile printing machine 1 can prevent the print medium M from slackening in the transport path downstream of the print head 22.

[0054] In this embodiment, the lower limit position P2 of the upstream tension bar 5 is located above the shaft 31A of the master winding unit 3. Therefore, as the tension applied to the printing medium M increases, the upstream tension bar 5 can be automatically moved upward.

[0055] Returning to FIG. 8 , the CPU 91 determines whether printing has finished (S13). Until printing has finished (S13: NO), the CPU 91 returns to S12 and continues to rotate the feed motor 81 forward. If printing has finished (S13: YES), the CPU 91 stops the feed motor 81 (S14). Therefore, the transport of the print medium M stops. The CPU 91 determines whether the power button 46 has been operated to turn off the power (S15). If the power has been turned off (S15: YES), the CPU 91 ends this process. If the power has not been turned off (S15: NO), the CPU 91 returns to S11.

[0056] <When Switching Back> If printing by the printing unit 2 has not started (S11), the CPU 91 determines whether to perform a switchback (S16). A switchback refers to the operation of transporting the print medium M in the F2 direction (see FIG. 6). The F2 direction is the opposite direction to the F1 direction, which is the transport direction. A switchback is preferably performed after printing is completed. For example, after printing an image on the print medium M, the interval between the next printed image needs to be shortened, double printing (overprinting) is required, drying is performed with the heater 13 after printing, or the unprinted portion of the print medium M is sent to the heater 13 and then returned to the print head 22. If a switchback is to be performed (S16: YES), the CPU 91 reverses the feed motor 81 (S17) and performs the switchback.

[0057] 6, when the transport roller 8 rotates in the direction C2, the print medium M on the platen 21 is transported in the direction F2, which is opposite to the direction F1. The switchback amount may be set in advance. The switchback amount is the distance the print medium M is transported in the reverse direction.

[0058] When the printing medium M is transported in the opposite direction, in the direction F2, the tension on the printing medium M gradually loosens, causing the upstream tension bar 5 to swing downward. If the switchback continues and the upstream tension bar 5 swings to the lower limit position P2, slack may occur in the printing medium M. The CPU 91 reverses the master winding motor 32 during the master winding motor control process (see FIG. 9), which will be described later, and rotates the shaft 31A in the opposite direction (the direction A2 shown in FIG. 6), thereby winding up the slackened printing medium M.

[0059] At this time, the printing medium M is pulled downward via the registration rollers 6, and a torque in the opposite direction to that during forward rotation is applied to the registration rollers 6. As described above, the one-way clutch 67 (see FIG. 5) causes the registration rollers 6 to rotate freely relative to the rotating shaft 61, so that the registration rollers 6 rotate in the direction B2, which is opposite to the feed direction, in response to the reverse movement of the printing medium M.

[0060] Returning to FIG. 8 , the CPU 91 determines whether the switchback amount has reached a predetermined amount (S18). The predetermined amount is set in advance depending on the switchback situation. If the switchback amount has not reached the predetermined amount (S18: NO), the CPU 91 returns to S17 and continues to reverse the feed motor 81. If the switchback amount has reached the predetermined amount (S18: YES), the CPU 91 stops driving the feed motor 81 (S14) and ends the switchback. If the power button 46 is operated to turn off the power (S15: YES), the CPU 91 ends this process.

[0061] The master winding motor drive control process will be described with reference to Figure 9. This process is executed separately from the feed motor control process, and controls the drive of the master winding motor 32 in accordance with the swing position of the upstream tension bar 5. When the user operates the power button 46, the CPU 91 reads out the master winding motor control program from the ROM 92 and executes this process.

[0062] The CPU 91 determines whether the upper limit sensor 51 is turned on (S21). When the tension on the printing medium M is strong, the upstream tension bar 5 swings upward. When the upstream tension bar 5 reaches the upper limit position P1, the upper limit sensor 51 turns on (S21: YES), and the CPU 91 rotates the master winding motor 32 forward (S22). This rotates the shaft 31A in the A1 direction, and the printing medium M is unwound from the master roll 100. As the printing medium M is unwound, the tension on the printing medium M decreases, and the upstream tension bar 5 swings downward under its own weight. When the upstream tension bar 5 swings downward from the upper limit position P1, the upper limit sensor 51 turns off. The CPU 91 then determines whether the power is turned off (S23). If the power is turned off (S23: YES), the CPU 91 ends this process. If the power is not turned off (S23: NO), the CPU 91 returns to S21.

[0063] If the upper limit sensor 51 is off (S21: NO), the CPU 91 determines whether the lower limit sensor 52 is on (S24). If the tension on the printing medium M is weak, the upstream tension bar 5 swings downward under its own weight. When the upstream tension bar 5 reaches the lower limit position P2, the lower limit sensor 52 turns on (S24: YES), and the CPU 91 reverses the master winding motor 32 (S25). This causes the shaft 31A to rotate reversely in the A2 direction, winding the printing medium M onto the master roll 100 and increasing the tension on the printing medium M. In this way, the upstream tension bar 5 repeatedly swings up and down between the upper limit position P1 and the lower limit position P2 depending on the tension on the printing medium M, thereby maintaining the tension on the printing medium M appropriately. If the power is turned off (S23: YES), the CPU 91 ends this process.

[0064] In the above description, the print head 22 is an example of a recording head of the present invention. The master winding unit 3 is an example of a master winding section of the present invention. The upstream tension bar 5 is an example of a tension bar of the present invention. The transport roller 8 is an example of a transport roller of the present invention. The registration roller 6 is an example of a roller of the present invention. The swing arm 25 is an example of an arm of the present invention. The upper limit sensor 51 is an example of a first photointerrupter of the present invention, and the lower limit sensor 52 is an example of a second photointerrupter of the present invention. The shielding section 352 of the shielding member 35 is an example of a first shielding section of the present invention, and the shielding section 362 of the shielding member 36 is an example of a second shielding section of the present invention.

[0065] As described above, the textile printing machine 1 of this embodiment includes the platen 21, print head 22, master winding unit 3, upstream tension bar 5, detection unit 50, transport roller 8, and CPU 91. The platen 21 supports the print medium M. The print head 22 ejects ink onto the print medium M supported on the platen 21 to perform printing. The master winding unit 3 supports the master roll 100 and feeds the print medium M toward the platen 21. The upstream tension bar 5 contacts the print medium M fed from the master winding unit 3 and applies tension to the print medium M by swinging under its own weight in accordance with the slack in the print medium M. The detection unit 50 detects the position of the upstream tension bar 5. The transport roller 8 is located downstream of the upstream tension bar 5 in the transport direction of the print medium M, and can transport the print medium M in direction F1 (transport direction) and direction F2 (opposite the transport direction). When the print medium M is transported in the F2 direction by the transport rollers 8, the CPU 91 rotates the shaft 31A of the master winding unit 3 in the A2 direction, which is opposite to the A1 direction, which is the feed direction of the print medium M, based on the detection result of the detection unit 50. When a so-called "switchback" occurs, in which the print medium M is transported in the F2 direction, the tension that had been applied to the print medium M until then is released. At this time, the upstream tension bar 5 swings in the direction of gravity and changes position. Therefore, based on the position of the upstream tension bar 5 detected by the detection unit 50, the CPU 91 reverses the rotation of the shaft 31A of the master winding unit 3, thereby winding up unnecessary slack in the print medium M. This allows the textile printing machine 1 to prevent tension problems from occurring when printing on the next print medium M.

[0066] When the detection unit 50 detects that the upstream tension bar 5 is located at the lower limit position P2 of the trajectory Q1, the CPU 91 rotates the shaft 31A of the master winding unit 3 in the A2 direction. For example, if the switchback amount is small and the upstream tension bar 5 does not swing to the lower limit position P2, there is no need to drive the master winding unit 3. In this case, unnecessary slack in the printing medium M can be taken up by swinging the upstream tension bar 5 alone.

[0067] Even if the transport roller 8 is disposed downstream of the print head 22 in the transport direction, it is possible to reduce the occurrence of slack due to switchback, thereby suppressing any impact on the print quality of the print medium M. For example, even soft cloth can be printed on by the print head 22 without slack.

[0068] The lower limit position P2 of the upstream tension bar 5 is above the shaft 31A of the master winding unit 3. Therefore, the textile printing machine 1 can automatically swing the upstream tension bar 5 upward as the tension of the printing medium M increases.

[0069] The textile printing machine 1 is equipped with a registration roller 6. The registration roller 6 is disposed between the platen 21 and the upstream tension bar 5, and is fitted with a torque limiter 66. When a rotational load exceeding a predetermined torque is applied to the registration roller 6, the torque limiter 66 transmits the predetermined torque to the printing medium M while causing slippage. The upstream tension bar 5 swings around the rotation shaft 26, and the registration roller 6 is disposed outside a locus Q1 centered on the rotation shaft 26 of the upstream tension bar 5. Therefore, the textile printing machine 1 can swing the upstream tension bar 5 against its own weight in accordance with the tension applied when the printing medium M is transported.

[0070] When the detection unit 50 detects that the upstream tension bar 5 is located at the upper limit position P1 of the locus Q1, the CPU 91 rotates the shaft 31A of the master winding unit 3 in the A1 direction. Since the master winding unit 3 can pay out the printing medium M, the textile printing machine 1 can maintain a state in which the printing medium M is properly tensioned.

[0071] The printing machine 1 includes a swing arm 25. The swing arm 25 swingably supports the upstream tension bar 5 around a rotation shaft 26. The detection unit 50 includes an upper limit sensor 51 and a lower limit sensor 52. The upper limit sensor 51 and the lower limit sensor 52 are photointerrupters. The swing arm 25 is provided with shielding members 35, 36. When the upstream tension bar 5 is located at the upper limit position P1, the shielding portion 352 of the shielding member 35 is detected by the upper limit sensor 51. When the upstream tension bar 5 is located at the lower limit position P2, the shielding portion 362 of the shielding member 36 is detected by the lower limit sensor 52. Therefore, the printing machine 1 can accurately detect two positions of the upstream tension bar 5 using two photointerrupters.

[0072] The present invention is not limited to the above embodiment and various modifications are possible. In this embodiment, the textile printing machine 1 is equipped with a print head 22 that mainly ejects ink, but the printing machine 1 may also be a recording device equipped with a recording head that ejects a liquid other than ink, such as a pretreatment liquid for double printing (overprinting).

[0073] The position of the heater 13 is not limited to the position in the above embodiment as long as it is downstream of the printing unit 2, and may be, for example, directly above the platen 21. The heater 13 does not have to be provided. As long as it can dry the printing surface M1 of the printing medium M, a dryer that blows warm air may be used instead of the heater 13.

[0074] The print head 22 is a piezo type print head, but may be of another type, such as a thermal head.

[0075] 1, the sizes of the shaft 31A, holder 31, upstream tension bar 5, registration roller 6, transport roller 8, downstream intermediate roller 9, downstream tension bar 10 of the master winding unit 3, and the shaft 41A and holder 41 of the winding unit 4 are merely examples and may be changed as appropriate. The upstream intermediate roller 7 and downstream intermediate roller 9 may be omitted, or the number of these intermediate rollers may be increased.

[0076] Although the upper limit sensor 51 and lower limit sensor 52 of the detection unit 50 are both photointerrupters, other methods may be used to detect the swing position of the upstream tension bar 5, for example, physical switches may be used. For example, a first switch may be provided that comes into physical contact with the swing arm 25 when the upstream tension bar 5 reaches the upper limit position P1, and a second switch may be provided that comes into physical contact with the swing arm 25 when the upstream tension bar 5 reaches the lower limit position P2.

[0077] REFERENCE SIGNS LIST 1 Textile printing machine 3 Master winding unit 5 Upstream dancer roller 6 Registration roller 8 Conveyor roller 21 Platen 22 Print head 26 Rotating shaft 31 Master winding roller 31A Shaft 50 Detecting section 51 Upper limit sensor 52 Lower limit sensor 61 Rotating shaft 66 Torque limiter 91 CPU 352 Shielding section 362 Shielding section M Printing medium P1 Upper limit position P2 Lower limit position

Claims

1. A recording device comprising: a platen that supports a recording medium; a recording head that ejects a recording agent onto the recording medium supported on the platen; a main winding unit that feeds the recording medium from a roll of the recording medium wound into a roll toward the platen; a tension bar that contacts the recording medium fed from the main winding unit and applies tension by oscillating in accordance with slack in the recording medium; a detection unit that detects the position of the tension bar; a transport roller that is positioned downstream of the tension bar in the transport direction of the recording medium and is capable of transporting the recording medium in the transport direction and in a direction opposite to the transport direction; and a control unit that drives the main winding unit in the direction opposite to the feed direction of the recording medium based on the detection result of the detection unit.

2. The recording device according to claim 1, characterized in that the control unit drives the master winding unit in the opposite direction when the detection unit detects that the tension bar is at the lower limit of its swing range.

3. The recording apparatus according to claim 1, wherein the transport roller is disposed downstream of the recording head in the transport direction.

4. The recording device according to claim 2, characterized in that the lower limit position of the tension bar is above the original winding portion.

5. The recording device according to claim 1, characterized in that it is provided with a roller with a torque limiter arranged between the platen and the tension bar in the transport path of the recording medium, the tension bar oscillates around a rotation axis, and the roller is arranged outside the rotation locus of the tension bar around the rotation axis.

6. The recording device according to claim 2, wherein the control unit drives the master winding unit in the feed direction when the detection unit detects that the tension bar is at the upper limit position of the swing range.

7. A recording device as described in claim 6, characterized in that it comprises an arm that supports the tension bar so that it can swing freely around a rotation axis, the detection unit comprises a first photointerrupter and a second photointerrupter, and the arm is provided with a first shielding part that is detected by the first photointerrupter when the tension bar is located at the upper limit position, and a second shielding part that is detected by the second photointerrupter when the tension bar is located at the lower limit position.

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