Printer

Abstract

To provide a printer which is configured to prevent and suppress the occurrence of overlapped feeding so as to eliminate the overlapped feeding and prevent and suppress the occurrence of successive supply of paper.SOLUTION: A printer 100 comprises: a pick-up roller 81 and a feed roller 82 which are fixed to a main body of the printer 100, and rotate in synchronization; a paper tray 20 that stores a number of sheets of paper S and can move up and down a hopper 21a that is a portion of a bottom plate 21; a retard roller 84 that comes into contact with the feed roller 82 in a state where the paper tray 20 is attached to the main body of the printer 100, and conveys the sheets of paper S stored in the paper tray 20 by sandwiching the paper between itself and the feed roller 82; and a control part 90 that controls operations of the pick-up roller 81, the feed roller 82, and the hopper 21a. The control part 90 performs overlapped-feeding eliminating processing, successive paper-feeding preventing processing, and main paper supplying processing.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a printer. [Background technology]

[0002] The printer is equipped with a pull-out paper tray on the main body. The paper tray holds a large number of stacked sheets of paper (hereinafter referred to as paper) cut to a specified size. The printer's main body is equipped with a pickup roller and a feed roller that rotate in contact with the topmost sheet of paper among the many sheets of paper held in the paper tray, thereby sending the paper to the paper feed path.

[0003] When the paper is fed out by the pickup roller and feed roller, a double feed may occur in which the second sheet of paper stacked directly below the topmost sheet (the sheet placed next to the topmost sheet) is fed out together with the topmost sheet while overlapping it due to static electricity, etc. If a double feed occurs, it may cause a paper jam on the path of the subsequent paper or cause printing misalignment in the printing section.

[0004] To prevent this, a retard roller is placed in contact with the feed roller, and the paper is sandwiched between the feed roller and the retard roller to feed it. In this case, the torque of the feed roller is applied to the topmost sheet of paper that is in contact with the feed roller, so the topmost sheet of paper is fed. Since the retard roller is applied with a torque in the opposite direction to the feed direction of the feed roller, the second sheet of paper that has advanced on top of the topmost sheet of paper is stopped by the torque of the retard roller and separated from the topmost sheet of paper, eliminating the double feed.

[0005] If the second sheet is left in contact with the retard roller, it will come into contact with the feed roller when the top sheet leaves the feed roller, and the second sheet will be fed. This results in continuous feeding, where the second sheet is fed without a sufficient gap between it and the top sheet that was fed first. Continuous feeding makes it difficult to control the transport and printing as previously set, because there is not enough space between the sheets.

[0006] In order to avoid continuous paper feeding, techniques have been proposed to ensure sufficient spacing between the top sheet and the second sheet by cutting off the driving force to the feed roller or by reversing the rotation of the feed roller to feed the second sheet back (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 6-250475 [Patent Document 2] Patent No. 4046993 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the technology described in the above-mentioned patent document does not return the second sheet of paper to the state it was in before it was double-fed. Therefore, if the second sheet of paper stops immediately after it leaves the retard roller, the next time the feed roller rotates, conveyance may begin if the leading edge of the second sheet of paper merely lightly touches the feed roller.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a printer that can prevent or suppress the occurrence of multi-feeding, and, even if multi-feeding does occur, can reliably return the second sheet of paper that was fed in a multi-feed to the state it was in before the multi-feeding, thereby resolving the multi-feeding, and also prevents or suppresses continuous paper feeding. [Means for solving the problem]

[0010] The present invention includes a pickup roller and a feed roller fixed to a main body of a printer and rotating in synchronism with each other, a paper tray that stores a large number of sheets and has a hopper that is a part of a bottom plate that can be moved up and down, a retard rotor that contacts the feed roller and conveys the paper stored in the paper tray by sandwiching it between the feed roller and the paper tray when the paper tray is attached to the main body of the printer, and a control unit that controls the operation of the pickup roller, the feed roller, and the hopper, and the control unit is configured to: (1) rotate the pickup roller in a forward direction corresponding to the forward direction of the paper to rotate the topmost paper to the forward direction of the paper; (2) after the double-feed elimination process, the hopper is lowered and the feed roller is rotated in a reverse direction opposite to the forward rotation direction to separate the second sheet of paper from the top sheet, thereby performing a continuous-feed prevention process, in which the second sheet of paper is separated from the retard roller, by feeding the top sheet in a forward direction and sandwiching the top sheet between the feed roller and the retard roller and feeding it in the forward direction; (3) after the continuous-feed prevention process, the feed roller is rotated in the forward rotation direction to perform a main feeding process, in which the top sheet of paper is fed. Effect of the Invention

[0011] The printer of the present invention prevents or suppresses the occurrence of multi-feeds, and even if a multi-feed does occur, it reliably returns the second sheet of paper to the state it was in before the multi-feed occurred, eliminating the multi-feed, and also prevents or suppresses continuous paper feeding. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a vertical plane passing through the center in the width direction W and along the front-rear direction L of a dye-sublimation thermal printer (hereinafter referred to as the printer). [Diagram 2] FIG. [Diagram 3]FIG. 2 is a simplified schematic representation of FIG. 1. [Figure 4] 2 is a partial cross-sectional view equivalent to FIG. 1 for explaining the structures and functions of a pickup roller, a feed roller and a retard roller. FIG. [Figure 5A] FIG. 13 is a schematic diagram (part 1) illustrating an operation when paper S stored in a paper tray is fed to a feeding path P1 under the control of a control unit, showing an initial state. [Figure 5B] FIG. 2 is a schematic diagram (part 2) illustrating the operation when the paper S stored in the paper tray is fed to the feeding path P1 under the control of the control unit, and shows a state in which the hopper is lifted upward. [Figure 5C] FIG. 13 is a schematic diagram (part 3) illustrating the operation when the paper S stored in the paper tray is fed to the feeding path P1 under the control of the control unit, showing the sorting process. [Figure 5D] FIG. 4 is a schematic diagram (part 4) for explaining the operation when the paper S stored in the paper tray is fed to the feeding path P1 under the control of the control unit, and shows the state in which the hopper is lowered downward after the separating process. [Figure 5E] FIG. 5 is a schematic diagram (part 5) for explaining the operation when the paper S stored in the paper tray is fed to the feeding path P1 under the control of the control unit, showing the looseness adjustment process. [Figure 5F] This is a schematic diagram (part 6) that explains the operation when paper S stored in the paper tray is fed to the feed path P1 under the control of the control unit, and shows the process of lifting the hopper upward and sending the paper in the forward direction. [Figure 5G] This is a schematic diagram (part 7) that explains the operation when paper S stored in the paper tray is fed to the feed path P1 under the control of the control unit, and shows the process of feeding the paper in the forward direction by the feed roller and the retard roller. [Figure 5H] FIG. 8 is a schematic diagram (part 8) illustrating the operation when the paper S stored in the paper tray is fed to the feeding path P1 under the control of the control unit, and shows the double feeding elimination process. [Figure 5I]FIG. 9 is a schematic diagram (part 9) for explaining the operation when the paper S stored in the paper tray is fed to the feed path P1 under the control of the control unit, and shows a state in which the rotation of the feed roller is stopped. [Figure 5J] FIG. 10 is a schematic diagram (part 10) for explaining the operation when the paper S stored in the paper tray is fed to the feeding path P1 under the control of the control unit, and shows the state in which the hopper is lowered downward. [Figure 5K] FIG. 11 is a schematic diagram (part 11) for explaining the operation when the sheet S stored in the sheet tray is fed to the feeding path P1 under the control of the control unit, and shows the continuous feeding prevention process. [Figure 5L] FIG. 12 is a schematic diagram (part 12) for explaining the operation when the paper S stored in the paper tray is fed to the feeding path P1 under the control of the control unit, and shows vibration processing. [Figure 5M] FIG. 13 is a schematic diagram (part 13) for explaining the operation when the paper S stored in the paper tray is fed to the feed path P1 under the control of the control unit, showing the main paper feeding process. [Figure 6] 11 is a flowchart showing a process performed by the control unit to feed paper from a paper tray to a feeding path. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a printer according to the present invention will be described as follows with reference to the drawings.

[0014] [Printer overall configuration] FIG. 1 is a cross-sectional view of a vertical plane passing through the center in the width direction W and along the front-rear direction L of a dye-sublimation thermal printer 100 (hereinafter referred to as the printer 100).

[0015] The illustrated printer 100 is one embodiment of a printer according to the present invention. The printer 100 can store both sheets of paper S (hereinafter simply referred to as paper S) that have been cut to a predetermined size in advance, and roll paper R (hereinafter simply referred to as paper R) that is a long, strip-shaped sheet of paper wound into a roll, and can selectively print and output on either one of the papers S and R.

[0016] The printer 100 includes a case 10, a paper tray 20, a printing section 30, a cutter section 40, a creasing section 50, a roll paper storage section 60, a transport means 70, a control section 90, and a transport path P.

[0017] <Case> The case 10 is an exterior cover that houses the printing unit 30, cutter unit 40, creasing unit 50, roll paper storage unit 60, transport means 70, control unit 90 and transport path P, and the case 10, printing unit 30, cutter unit 40, creasing unit 50, roll paper storage unit 60, transport means 70, control unit 90 and transport path P form the main body of the printer 100. As will be described later, the paper tray 20 is detachable from the main body of the printer 100. An outlet 15 is formed in the front panel that covers the front of the case 10 in the length direction L, through which printed papers S and R are discharged.

[0018] <Paper tray> FIG. 2 is a perspective view showing the paper tray 20. The paper tray 20 stores a large number of papers S (sheets S) stacked in the thickness direction. The paper tray 20 is removably attached to the main body of the printer 100 in a drawer type. Specifically, the paper tray 20 is disposed at the bottom of the printer 100, and can be removed from the main body of the printer 100 by pulling it forward in the front-rear direction L as shown by the outlined arrow in FIG. 1. The paper tray 20 removed from the main body of the printer 100 is attached to the main body of the printer 100 as shown in FIG. 1.

[0019] As shown in FIG. 2, the paper tray 20 is formed in a thin box-like shape (tray) with no top plate, and is made up of a bottom plate 21 on which the paper S is stacked, side plates 24, 25 that rise in the thickness direction of the paper S (height direction H of the printer 100) on both sides of the width direction W, a rear plate 23 that rises at the rear side in the front-to-rear direction L, and a front plate 22 that rises at the front side in the front-to-rear direction L.

[0020] The front portion 21a, which is a part of the bottom plate 21, is formed so as to be able to swing upward about the rear end of the front portion 21a as an axis C3. In other words, the front portion 21a serves as a hopper that lifts up the front portion of the paper S placed on the bottom plate 21 in an upwardly inclined state. Hereinafter, this front portion 21a will be referred to as the hopper 21a.

[0021] The hopper 21a is moved up and down by driving a motor (not shown) provided in the main body of the printer 100. Specifically, the control unit 90 drives the motor provided in the main body of the printer 100, causing a plate 19 (see FIGS. 1 and 4) provided on the main body to push up the hopper 21a from an opening 20A (see FIG. 1) formed in the bottom surface of the paper tray 20, whereby the hopper 21a is lifted upward and assumes an inclined position (indicated by a two-dot chain line in FIG. 2).

[0022] The paper tray 20 has an inclined plate 27 that extends obliquely upward and forward from the upper end of the front plate 22. In other words, the inclined plate 27 is inclined downward toward the rear. An opening 27d is formed in the center of the inclined plate 27 in the width direction W. A portion of the inclined plate 27 adjacent to the opening 27d is hereinafter referred to as an inclined portion 27a.

[0023] The paper tray 20 has a front cover member 26 connected to the inclined plate 27 and to portions of the side plates 24, 25 that extend further forward than the front plate 22. The front cover member 26 is formed to extend in the width direction W forward of the front plate 22. The front cover member 26 is formed to extend further outward in the width direction W than the side plates 24, 25, respectively.

[0024] The paper tray 20 removed from the main body of the printer 100 is attached to the main body of the printer 100 as shown in Fig. 1 by pushing the front cover member 26 from the front to the rear in the front-to-rear direction L (the opposite direction of the white arrow in Fig. 1) into a space formed at the bottom of the printer 100 and extending in the front-to-rear direction L. Then, with the paper tray 20 attached to the main body of the printer 100, the front cover member 26, together with the case 10, forms the front surface of the printer 100 in the front-to-rear direction L.

[0025] The paper tray 20 is equipped with a retard roller 84 shown in Fig. 2. The retard roller 84 is disposed in a space in front of the paper tray 20, which is formed between the front plate 22 and the front cover member 26. A part of the retard roller 84 protrudes upward from the surface of the inclined portion 27a of the inclined plate 27 through an opening 27d formed in the inclined plate 27.

[0026] The hopper 21a is configured to incline upward so that, regardless of the number of sheets of paper S stored in the paper tray 20, the topmost sheet of paper S among the sheets of paper S lifted by the hopper 21a hits the pickup roller 81, lifting the pickup roller 81, and the extension line of the leading edge of the sheet of paper S hits the rear end of the inclined plate 27 without contacting the feed roller 82.

[0027] 2, the retard roller 84 provided on the paper tray 20 faces the inside of the paper tray 20 through an opening 27d of the inclined plate 27 of the paper tray 20. Then, as shown in FIG. 1, when the paper tray 20 is attached to the main body of the printer 100 in the normal position, the retard roller 84 is disposed so as to come into contact with the feed roller 82 fixed to the main body of the printer 100.

[0028] <Roll paper storage section> The roll paper storage section 60 is formed above the paper tray 20, on the front side in the front-rear direction L. The roll paper storage section 60 is a section that stores roll paper R. In Fig. 1, the roll paper storage section 60 stores roll paper R with the axis of the roll paper R parallel to the width direction W of the printer 100, and with the paper wound counterclockwise from the center to the outer periphery. The roll paper R stored in the roll paper storage section 60 rotates counterclockwise as shown in the figure by being pulled out from the bottom end of the roll paper R to the right in Fig. 1 and unwound.

[0029] <Printing Department> The printing unit 30 is disposed behind the roll paper storage unit 60 in the front-to-rear direction L. Under the control of the control unit 90, the printing unit 30 prints on the sheets S and R passing through a portion of the transport path P that rises in a substantially vertical direction behind the roll paper storage unit 60 (printing path P3, described later).

[0030] The printing unit 30 includes a thermal head 31, an ink ribbon 32, and a platen roller 33. A sublimation dye is applied to the ink ribbon 32. The ink ribbon 32 is fed from a feed roll 32a to a take-up roll 32b in synchronization with the transport of the papers S and R, and the heat generated by the thermal head 31 in contact with the ink ribbon 32 causes the sublimation dye of the ink ribbon 32 to be diffused and transferred to the papers S and R, thereby performing printing.

[0031] The platen roller 33 is disposed on the opposite side of the ink ribbon 32 and thermal head 31, with the papers S and R conveyed along a print path P3 (described later) sandwiched therebetween. The platen roller 33 presses the papers S and R against the ink ribbon 32.

[0032] <Cutter section> The cutter unit 40 is disposed in front of the roll paper storage unit 60. The cutter unit 40 operates under the control of the control unit 90. The cutter unit 40 cuts the paper R in the width direction W as it passes through a portion of the transport path P that extends forward from above the roll paper storage unit 60 (discharge path P9, described below). As described above, the cutter unit 40 cuts the paper R, which is roll paper, to a predetermined length, but it can also cut off unnecessary ends of the paper S, which is a sheet of paper.

[0033] <Creasing part> The creasing unit 50 is located behind the roll paper storage unit 60 in the front-to-rear direction L, and between the printing unit 30 and the paper tray 20 in the height direction H. The creasing unit 50 operates under the control of the control unit 90. The creasing unit 50 forms creases, which are depressions extending along the width direction W, in the paper S that passes through a portion of the transport path P that extends below the roll paper storage unit 60 in the front-to-rear direction L (the creasing path P7 described below). Note that the creasing unit 50 forms creases in the paper S, which is a sheet of paper, as described above, but it may also form creases in the paper R, which is a roll of paper, by controlling the cutting and transport.

[0034] <Transport path> Figure 3 is a schematic diagram that simplifies Figure 1 to clarify the transport path P. The transport path P is a passage along which the sheets S and R are transported by the transport means 70, and is indicated by a dashed line in Figure 3. The symbol Q shown beside the transport path P indicates the forward direction in which the sheet S is transported from the paper tray 20 toward the outlet 15 and the forward direction in which the sheet R is transported from the roll paper storage section 60 toward the outlet 15, and the symbol -Q indicates the reverse direction that is opposite to the forward direction Q.

[0035] The transport path P has a sheet delivery path P1, a sheet feed path P2, a printing path P3, a standby path P4, a printing lower path P5, a reversal standby path P6, a creasing path P7, a roll paper feed path P8, and a discharge path P9.

[0036] The sheet feed path P1 (hereinafter, simply referred to as the feed path P1) is a transport path along which the paper S stored in the paper tray 20 is fed out one sheet at a time. The feed path P1 is formed by extending diagonally upward toward the front from the front end of the paper tray 20. The means for feeding the paper S from the paper tray 20 to the feed path P1 are a pickup roller 81 and a feed roller 82 provided in the main body of the printer 100, but in order to prevent double feeding of the paper S, a retard roller 84 provided in the paper tray 20 is also used.

[0037] When the paper S is fed, the hopper 21a of the paper tray 20 is raised, and the operation of feeding the paper S will be described later together with the structure of the retard roller 84.

[0038] The sheet paper feed path P2 (hereinafter simply referred to as the paper feed path P2) is a transport path continuing from the unwinding path P1, extending upward from the front end of the unwinding path P1, then turning back and extending downward in the space formed in front of the roll paper storage section 60, extending rearward through the space between the roll paper storage section 60 and the paper tray 20, and further extending to an upward position behind the roll paper storage section 60.

[0039] The printing path P3 continues from the front end of the paper feed path P2, rising upward along the rear of the roll paper accommodation unit 60, and then extends forward to the upper front part of the roll paper accommodation unit 60. The platen roller 33 and thermal head 31 of the printing unit 30 described above are positioned to face each other with the printing path P3 in between.

[0040] The standby path P4 follows the printing path P3 and extends from the front end of the printing path P3 to the upper front part of the roll paper storage section 60, and then extends downward in front of the roll paper storage section 60 in a concentric circle with the outer periphery of the roll paper storage section 60 to a position just before it hits the paper feed path P2.

[0041] The printing downstream path P5 is formed to extend obliquely downward and forward from the rear end of the printing path P3, following the printing path P3, and passes outside the paper feed path P2 behind the roll paper accommodation unit 60.

[0042] The reversal waiting path P6 is formed so as to extend from the front end of the lower printing path P5 to the front in the front-rear direction L through the space between the paper feed path P2 and the paper tray 20, and so as to connect its front end to the rear end of the paper feed path P2. The paper S passing through the reversal waiting path P6 has already been printed on its downward side as shown, and by being transported again through the paper feed path P2 from the reversal waiting path P6, the upward side of the paper S in the reversal waiting path P6 becomes the target for printing in the printing unit 30 when it next passes through the printing path P3. Therefore, the reversal waiting path P6 and the paper feed path P2 form a reversal path that reverses the front and back sides of the paper S.

[0043] The creasing path P7 is formed so as to extend from the rear end of the reversing standby path P6 to above the paper tray 20 and rearward in the front-rear direction L. The creasing section 50 is disposed on the creasing path P7.

[0044] The roll paper feed path P8 extends rearward from approximately the bottom of the roll paper accommodation unit 60, rises upward at the rear of the roll paper accommodation unit 60, and is formed to the rear end of the print path P3.

[0045] The discharge path P9 is formed contiguous to the printing path P3, from the front end of the printing path P3, above the roll paper accommodation unit 60, toward the front in the front-rear direction L, to the discharge opening 15. The cutter unit 40 is formed in the discharge path P9.

[0046] <Transportation means> The conveying means 70 is provided on the conveying path P. The conveying means 70 operates under the control of the control unit 90. The conveying means 70 conveys the papers S, R along the conveying path P, and also switches the conveying path P to which the papers should be sent. The conveying means 70 is composed of a drive roller driven by a motor (not shown) controlled by the control unit 90, a driven roller having no driving force, switching members 71, 72, 73 that switch the conveying path P, and the like.

[0047] Of the conveying means 70, illustrations and descriptions are omitted for those configured with normal drive rollers and driven rollers that sandwich and feed the sheets S and R. The conveying means 70 includes a pickup roller 81, a feed roller 82, and a retard roller 84 that deliver the sheet S from the paper tray 20 to the delivery path P1. The pickup roller 81, the feed roller 82, and the retard roller 84 will be described later.

[0048] The switching member 71 is provided at the front end of the printing path P3. The switching member 71 switches between sending the sheets S, R sent in the forward direction Q on the printing path P3 to the standby path P4 for printing on the sheets S, R, or sending the sheets S, R to the discharge path P9 for discharge. The switching of the transport path by the switching member 71 is performed under the control of the control unit 90.

[0049] The switching member 72 is provided at the rear end of the printing path P3. The switching member 72 serves to return the paper S sent in the reverse direction -Q on the printing path P3 to the downstream printing path P5 without allowing it to erroneously enter the roll paper feed path P8. The switching member 72 is biased by a spring in the direction that blocks the roll paper feed path P8.

[0050] As a result, when the printed paper is the paper S which is a sheet, the switching member 72 sends the paper S sent in the reverse direction -Q on the printing path P3 to the printing downstream path P5.

[0051] On the other hand, when the printed paper is roll paper R, the switching member 72 is biased by a spring in the direction blocking the roll paper feed path P8, but because paper R is a continuous body, even if the leading edge of paper R has reached the printing path P3, the portion that is connected to the rolled paper R stored in the roll paper accommodation unit 60 pushes the switching member 72 apart against the bias of the spring to open the path to the roll paper feed path P8. Therefore, when paper R that has been sent in the reverse direction -Q on the printing path P3 is rewound into the roll paper feed path P8, the switching member 72 can rewind paper R into the roll paper feed path P8 without hindrance.

[0052] The switching member 73 is provided at the rear end of the lower printing path P5. The switching member 73 serves as a switching valve for reliably sending the sheet S, sent to the reverse waiting path P6, to the creasing path P7 without returning the sheet S to the lower printing path P5 when the sheet S is transported in the reverse direction -Q.

[0053] The switching member 73 biases the sheet S by a spring in the direction of sending the sheet S to the creasing path P7. After printing, the sheet S is placed in the reversing waiting path P6 up to its rear end, but while printing is being performed, the rear end of the sheet S remains in the lower printing path P5. In other words, during printing, the sheet S is not sent to the reversing waiting path P6 up to its rear end, and the rear end remains in the lower printing path P5.

[0054] Thereafter, for printing of the second and subsequent colors, the paper S is sent in the reverse direction -Q through the print downstream path P5 and returned to the standby path P4 again. Then, the printer 100 repeats the above-mentioned printing operation to perform multi-color printing and coating.

[0055] In this way, the paper S in the middle of multi-color printing is positioned across the reversal waiting path P6 and the printing downstream path P5, and the paper S in this state presses the switching member 73 against the spring force to the side that passes the paper S through the printing downstream path P5, thereby switching the side that sends the paper S to the printing downstream path P5.

[0056] (Pickup roller and feed roller) FIG. 4 is a partial cross-sectional view corresponding to FIG. 1, for explaining the structures and functions of the pickup roller 81, the feed roller 82 and the retard roller 84. As shown in FIG.

[0057] The pickup roller 81, the feed roller 82, and the retard roller 84 are part of the conveying means 70 that feeds the paper S from the paper tray 20 to the feed path P1. The retard roller 84 is not simply a driven roller, but generates a torque (reverse torque) in the opposite direction to the rotational direction so as to brake the rotation, and prevents double feeding, in which two or more sheets of paper are sent overlapping each other, when the paper S is fed.

[0058] The pickup roller 81 and the feed roller 82 are fixed to the main body of the printer 100 via an arm 83. When the paper tray 20 is attached to the main body of the printer 100, the pickup roller 81 and the feed roller 82 are disposed above the paper tray 20 and near where the front plate 22 of the paper tray 20 is formed in the front-rear direction L, that is, at a position above the paper tray 20 and corresponding to the front part.

[0059] The pickup roller 81 and the feed roller 82 are integrally formed by an arm 83. The arm 83 positions the pickup roller 81 behind the feed roller 82 in the front-rear direction L. The arm 83 is also positioned in an overall downwardly tilted position so that the pickup roller 81 is lower in the height direction H than the feed roller 82, but the arm 83 can rotate coaxially with the rotation axis of the feed roller 82, and is biased by a spring in a direction to press the pickup roller 81 against the paper S stored in the paper tray 20. The dimension between the rotation axes of the pickup roller 81 and the feed roller 82 is, for example, 20 mm.

[0060] The pickup roller 81 and the feed roller 82 are driven by a single motor that is driven under the control of the control unit 90. Therefore, the pickup roller 81 and the feed roller 82 rotate synchronously in a forward direction N and a reverse direction −N, or stop.

[0061] (Retard roller) As described above, the retard roller 84 is provided in the paper tray 20, and when the paper tray 20 is installed in the correct position in the main body of the printer 100, the retard roller 84 is positioned in contact with the lower front part of the feed roller 82, as shown in FIG. 4.

[0062] The retard roller 84 pinches the paper S between itself and the driven feed roller 82. The retard roller 84 is a driven roller, and the retard roller 84 itself does not drive, but the paper S pinched between itself and the feed roller 82 moves in the forward direction Q by the driving force of the feed roller 82, and is rotated in the forward direction N, and the paper S moves in the reverse direction -Q, and is rotated in the reverse direction -N.

[0063] When the retard roller 84 rotates around the axis C2, it generates a torque (reverse torque) in the opposite direction to the rotation direction to brake the rotation. The retard roller 84 is set so that the reverse torque when it rotates in the reverse direction -N (the rotation direction that feeds the paper S in the reverse direction -Q) is smaller than the reverse torque when it rotates in the forward direction N (the rotation direction that feeds the paper S in the forward direction Q).

[0064] <Control Unit> The control unit 90 is disposed above the paper tray 20 and behind the printing unit 30. The control unit 90 is equipped with a paper sensor that detects the papers S and R passing through a predetermined position on the transport path P. Paper sensors are provided at multiple locations on the transport path P, but only the paper sensor 92 provided on the delivery path P1 is described, and description and explanation of the other paper sensors are omitted.

[0065] The control unit 90 controls the operations of the printing unit 30, the cutting unit 40, the creasing unit 50, and the transport means 70, and controls the timing of each operation mainly based on the detection results of the paper sensor.

[0066] (Control of paper S (sheet S)) The printer 100 operates as follows with respect to the paper S passing through the above-mentioned transport path P. First, the control unit 90 controls the pickup roller 81, the feed roller 82, and the hopper 21a to feed the paper S stored in the paper tray 20 in the forward direction Q to the feeding path P1. Details of the control by the control unit 90 when feeding the paper S from the paper tray 20 will be described later.

[0067] Next, the control unit 90 controls the transport means 70 to feed the paper S in the forward direction Q from the delivery path P1 to the paper feed path P2, then to the print path P3, and then to the standby path P4.

[0068] The control unit 90 then controls the printing unit 30 to print on one side of the paper S (the side facing the thermal head 31) while feeding the paper S in the reverse direction -Q to the waiting path P4 and then to the printing path P3 in the reverse direction -Q. When the printing unit 30 is to perform multi-color printing on the paper S or to perform coating after printing, the control unit 90 repeatedly feeds the paper S in the forward direction Q and the reverse direction -Q through the printing path P3 and the waiting path P4.

[0069] The control unit 90 sends the paper S printed by the printing unit 30 to the printing downstream path P5 in the forward direction Q (corresponding to the reverse direction -Q in the printing path P3), then sends it in the forward direction Q to the reversing standby path P6, then sends it in the forward direction Q to the paper feed path P2, and then sends it in the forward direction Q to the printing path P3. As described above, the control unit 90 reverses the front and back sides of the paper S by passing the paper S through the reversing standby path P6 and the paper feed path P2.

[0070] When the printer 100 finishes printing only on one side of the paper S, the control unit 90 then sends the paper S in the forward direction Q to the discharge path P9 and discharges it from the discharge opening 15 to the outside of the printer 100, completing the process.

[0071] When the printer 100 prints on both sides of the paper S, the paper S fed in the forward direction Q to the print path P3 is fed in the forward direction Q to the waiting path P4.

[0072] The control unit 90 then sends the paper S in the reverse direction -Q to the waiting path P4, and then in the reverse direction -Q to the printing path P3, while the printing unit 30 prints on the other side of the paper S (the side facing the thermal head 31). When the printing unit 30 performs multi-color printing on the paper S or when coating after printing is performed, the control unit 90 repeatedly performs forward direction Q and reverse direction -Q feeding to the printing path P3 and the waiting path P4.

[0073] The control unit 90 then sends the paper S printed in the printing unit 30 in the forward direction Q to the printing lower path P5, then to the reverse waiting path P6 in the forward direction Q, then to the paper feed path P2 in the forward direction Q, then to the printing path P3 in the forward direction Q, then to the discharge path P9 in the forward direction Q, and finally discharges the paper S from the discharge outlet 15 to the outside of the printer 100.

[0074] When creasing is to be performed on the printed paper S, in the case of single-sided printing, the control unit 90 conveys the paper S after single-sided printing to the reversal waiting path P6, sends it in the reverse direction -Q to the reversal waiting path P6, and then sends it in the reverse direction -Q to the creasing path P7, where it is creasingly performed by the creasing unit 50.

[0075] When creasing is to be performed on the printed paper S, in the case of double-sided printing, the control unit 90 transports the paper S after double-sided printing to the reversal waiting path P6, sends it in the reverse direction -Q to the reversal waiting path P6, and then sends it in the reverse direction -Q to the creasing path P7, where creasing is performed on the paper S by the creasing unit 50 under the control of the control unit 90.

[0076] (Control over Paper R (Roll Paper R)) The printer 100 operates as follows with respect to the paper R passing through the above-mentioned transport path P. First, the control unit 90 controls the transport means 70 to pay out the paper R stored in the roll paper storage unit 60 in the forward direction Q to the roll paper feed path P8. As the roll paper R is paid out in the forward direction Q, it is unwound from the roll.

[0077] The control unit 90 then sends the paper R in the forward direction Q to the print path P3, and then sends it in the forward direction Q to the standby path P4.

[0078] The control unit 90 then controls the printing unit 30 to print on one side (the side facing the thermal head 31) of the paper R while returning the paper R to the waiting path P4 in the reverse direction -Q, and then to the printing path P3 in the reverse direction -Q. When the paper R is returned in the reverse direction -Q, it is rewound onto the roll.

[0079] When the printing unit 30 performs multi-color printing on the paper R or performs coating after printing, the control unit 90 repeatedly feeds the paper R in the forward direction Q and the reverse direction -Q through the printing path P3 and the waiting path P4.

[0080] The control unit 90 then sends the paper R printed by the printing unit 30 in the forward direction Q to the printing path P3, and then to the discharge path P9 in the forward direction Q, controls the cutter unit 40 to cut the paper R to a predetermined length, and discharges the printed paper R, which has been separated from the roll by the cut, outside the printer 100 through the discharge outlet 15, and the process is completed.

[0081] The portion of paper R that has been cut off and connected to the roll is rewound by the control unit 90 onto the roll in the roll paper storage unit 60, and is returned in the reverse direction -Q to the discharge path P9, the printing path P3, and the roll paper feed path P8.

[0082] (Details of the control of feeding paper from the paper tray by the control unit) Figures 5A to 5M are schematic diagrams explaining the operation when paper S stored in paper tray 20 is fed to feed path P1 under the control of control unit 90, and Figure 6 is a flowchart showing the process of feeding paper S from paper tray 20 to feed path P1 by control unit 90.

[0083] Next, the control performed by the control section 90 when the paper S stored in the paper tray 20 is fed to the feeding path P1 will be described in detail with reference to FIGS. 5A to 5M and 6. FIG.

[0084] (Cutting process) In the process of feeding the paper S to the feeding path P1 from the state in which the paper S is stored in the paper tray 20 as shown in Fig. 5A, the control unit 90 first drives a motor provided in the main body of the printer 100, which lifts the plate 19 and pushes the hopper 21a upward as shown in Fig. 5B. As a result, the front portions of all the papers S stored in the paper tray 20 are lifted, and the topmost paper S1 comes into contact with the pickup roller 81.

[0085] Here, when the direction in which the paper S is sent toward the feed path P1 is defined as the forward direction Q, the rotation direction of the pickup roller 81, the rotation direction of the feed roller 82, and the rotation direction of the retard roller 84 corresponding to sending the paper S in the forward direction Q is defined as the forward direction N, and the rotation direction of the pickup roller 81, the rotation direction of the feed roller 82, and the rotation direction of the retard roller 84 corresponding to sending the paper S in the reverse direction -Q, which is the opposite direction to the forward direction Q, is defined as the reverse direction -N.

[0086] Next, the control unit 90 controls the pickup roller 81 so that the pickup roller 81 rotates in the reverse direction -N as shown in Fig. 5C. The control unit 90 drives the pickup roller 81 by a rotation angle corresponding to sending the paper S in contact with the outer peripheral surface of the pickup roller 81 a distance of 10 [mm] in the reverse direction -Q.

[0087] As a result, the topmost sheet of paper S1 in contact with the pickup roller 81 is subjected to the torque of the pickup roller 81 and attempts to move in the reverse direction -Q, but the rear end of the sheet S1 in the front-to-rear direction abuts against the paper tray 20 and cannot move, so the unconstrained portion of the sheet S1 between the front end in contact with the pickup roller 81 and the rear end abutting against the paper tray 20 bends and bulges upward.

[0088] Here, the second sheet S2, which is stacked directly below the topmost sheet S1 and in contact with the topmost sheet S1, is not in contact with the pickup roller 81 and is therefore not subjected to the torque from the pickup roller 81 to move in the reverse direction -Q. Therefore, the topmost sheet S1, which receives the torque of the pickup roller 81, rises up, but the second sheet S2 does not rise up, so a gap is formed between the topmost sheet S1 and the second sheet S2 as shown in FIG. 5C, creating a layer of air.

[0089] As a result, the top sheet S1 and the second sheet S2 are in a separated state, making them easier to separate, and thus preventing double feeding. Hereinafter, the process in which the control unit 90 forms a gap between the top sheet S1 and the second sheet S2 is referred to as the separation process. Note that in the printer 100 of this embodiment, the control unit 90 does not need to always perform the separation process, and the separation process can be omitted.

[0090] (Leftover processing) The control unit 90 then controls the hopper 21a to move down as shown in FIG. 5D, so that all of the sheets S contained in the sheet tray 20 are separated from the pickup roller 81.

[0091] 5E, the control unit 90 rotates the pickup roller in the forward direction N while keeping the hopper 21a lowered. The control unit 90 drives the pickup roller 81 by a rotation angle corresponding to sending the paper S in contact with the outer circumferential surface of the pickup roller 81 a distance of 20 [mm] in the forward direction Q.

[0092] As a result, the play in the rotational direction of the pickup roller 81 and the feed roller 82 is shifted to the rear side in the forward rotation direction N, and when they subsequently rotate in the forward rotation direction N, they can be driven without play in the rotational direction, providing the effect of accurately feeding the paper S1 in the forward direction Q. In this way, the process in which the control unit 90 causes the pickup roller 81 and the feed roller 82 to rotate freely in the forward rotation direction N after the sorting process to eliminate play in the forward rotation direction N is hereinafter referred to as play adjustment process. Note that in the printer 100 of this embodiment, the control unit 90 does not need to always perform the play adjustment process, and the play adjustment process can be omitted.

[0093] (Multi-feed resolution process) The control unit 90 then controls the hopper 21a to raise, as shown in FIG. 5F, so that the top sheet S1 is in contact with the pickup roller 81, and the control unit 90 rotates the pickup roller 81 in the forward direction N, thereby moving the top sheet S1 in the forward direction Q.

[0094] When the topmost sheet S1 is sent in the forward direction Q, the leading edge of sheet S hits the rear end of inclined plate 27, but because the leading edge of sheet S1 is inclined upward, sheet S1 is bent so that the leading edge of sheet S1 escapes to the upper side of inclined plate 27. Then, the leading edge of sheet S1 comes into contact with retard roller 84, which is rotating forward in response to feed roller 82, and is further sandwiched between feed roller 82 and retard roller 84.

[0095] Here, if the second sheet of paper S2 is fed overlapping the topmost sheet of paper S1, the leading edge of the topmost sheet of paper S1 will hit the rear end of the inclined plate 27 and bend upward to escape. However, since the second sheet of paper S2 is unlikely to bend at the same time as the topmost sheet of paper S1, this has the effect of making it difficult for the second sheet of paper S2 to reach the retard roller 84.

[0096] The leading end of the topmost sheet S1, which has passed the pickup roller 81, is guided onto the surface of the inclined portion 27a of the inclined plate 27, and is sandwiched between the feed roller 82 and the retard roller 84, as shown in FIG. 5G, and is subjected to the torque caused by the rotation of the feed roller 82 in the forward direction N, and is sent in the forward direction Q toward the pay-out path P1.

[0097] A paper sensor 92 is positioned at a predetermined position on the pay-out path P1, and when the paper sensor 92 detects the passage of the leading end of the topmost paper S1 paid out on the pay-out path P1, the control unit 90 temporarily stops the rotation of the feed roller 82 in the forward direction N.

[0098] The paper sensor 92 is disposed at a distance of, for example, 30 mm along the payout path P1 in the forward direction Q from the position where the feed roller 82 and the retard roller 84 come into contact (at a distance of, for example, 50 mm from the pickup roller 81). The distance of 30 mm at which the paper sensor 92 is disposed is just an example, and the position of the paper sensor 92 is not limited to the distance of 30 mm.

[0099] Here, a case will be described where, despite the sorting process by control unit 90 shown in FIGS. 5B and 5C, a double feed occurs in which the second sheet S2 is fed overlapping the topmost sheet S1, as shown in FIG. 5H.

[0100] When a double feed occurs, when the control unit 90 rotates the pickup roller 81 in the forward direction N to move the top sheet S1 in the forward direction Q (see Figure 5F), the second sheet S2 adheres to the top sheet S1 due to factors such as static electricity, and the second sheet S2 moves in the forward direction Q together with the top sheet S1, and the top sheet S1 and the second sheet S2 reach a position where they are sandwiched between the feed roller 82 and the retard roller 84, as shown in Figure 5H.

[0101] Even if the double feed shown in Fig. 5H occurs, the control unit 90 controls the feed roller 82 to continue rotating in the forward direction N. The top surface of the top sheet S in contact with the feed roller 82 is subjected to a torque that sends the sheet in the forward direction Q due to friction with the feed roller 82 caused by the sheet being sandwiched between the retard roller 84 and the feed roller 82, and the sheet is sent in the forward direction Q in the same manner as when no double feed occurs.

[0102] Then, when the paper sensor 92 detects the passage of the leading end of the uppermost paper S1 fed out to the feed path P1, the control unit 90 stops the rotation of the feed roller 82 in the forward rotation direction N for a moment.

[0103] Meanwhile, the second sheet S is supplied with a propulsive force in the forward direction Q due to the frictional force with the topmost sheet S contacting its upper surface, but its lower surface contacts the retard roller 84, which generates a reverse torque in the opposite direction to the direction of rotation, and the force in the reverse direction -Q due to this reverse torque exceeds the frictional force in the forward direction Q, so the second sheet S2 stops in contact with the retard roller 84.

[0104] This allows the top sheet S to be separated from the second sheet S and sent in the forward direction Q, eliminating the double feed. The process in which the control unit 90 sends the top sheet S1 in the forward direction Q from a state in which the top sheet S1 is in contact with the pickup roller 81 until it passes between the feed roller 82 and the retard roller 84 and is detected by the sheet sensor 92, and separates the second sheet S2 from the top sheet S, is hereinafter referred to as the double feed elimination process.

[0105] The leading edge of the topmost sheet S1 that has reached the position of the sheet sensor 92 is shifted in the forward direction Q by approximately 30 [mm] from the leading edge of the second sheet S2 that has stopped with its leading edge in contact with the retard roller 84. When the position of the sheet sensor 92 is disposed at a distance X [mm] in the forward direction Q along the pay-out path P1 from the position where the feed roller 82 and the retard roller 84 are in contact, the leading edge of the topmost sheet S1 is shifted in the forward direction Q by approximately X [mm] from the leading edge of the second sheet S2.

[0106] (Prevention of continuous feeding) Next, the control unit 90 performs control to prevent continuous feeding, in which the second sheet S2 is fed without a predetermined interval immediately after the top sheet S1 is fed. That is, the printer 100 eliminates double feeding by the above-mentioned control of the control unit 90. However, when the rear end of the top sheet S1 finishes passing the feed roller 82 in the state shown in FIG. 5H, the feed roller 82 comes into contact with the top surface of the second sheet S2, so that the torque of the feed roller 82 in the forward direction Q acts on the top surface of the second sheet S2, and the second sheet S2 starts to be fed in the forward direction Q. As a result, continuous feeding occurs, in which the interval between the rear end of the top sheet S1 fed first and the front end of the second sheet S2 fed immediately afterwards becomes narrow.

[0107] Therefore, the control unit 90 controls the hopper 21a to be lowered as shown in Fig. 5J while temporarily stopping the rotation of the feed roller 82 in the forward direction N as shown in Fig. 5I. At this time, the top sheet S1 and the second sheet S2 are sandwiched between the feed roller 82 and the retard roller 84 and do not fall into the paper tray 20, but all the sheets S stacked below the second sheet S2 fall into the paper tray 20.

[0108] Next, the control unit 90 controls the feed roller 82 to rotate in the reverse direction -N, as shown in Fig. 5K, while keeping the hopper 21a lowered. This rotation in the reverse direction -N is a rotation angle corresponding to a distance for feeding the uppermost sheet S1 in contact with the feed roller 82 in the reverse direction -Q by, for example, about 22 [mm].

[0109] Here, the retard roller 84 is set such that the counter torque for rotation in the reverse direction -N is smaller than the counter torque for rotation in the forward direction N, and this counter torque for the reverse direction -N is set smaller than the frictional force that the second sheet S2 receives from the uppermost sheet S fed in the reverse direction -Q. As a result, when the second sheet S2 tries to move in the reverse direction -Q due to the frictional force with the uppermost sheet S1, the retard roller 84 rotates in the reverse direction -N following the movement of the second sheet S2.

[0110] In this way, the top sheet S1 and the second sheet S2 sandwiched between the feed roller 82 and the retard roller 84 both move in the reverse direction -Q. Then, the top sheet S1 is sent approximately 22 [mm] in the reverse direction -Q and is sandwiched between the feed roller 82 and the retard roller 84, and the second sheet S2, like all the other sheets S stacked below the second sheet S2, falls into the paper tray 20 before being sent approximately 22 [mm] in the reverse direction -Q.

[0111] The rotation angle at which the feed roller 82 is rotated in the reverse direction -N should be such that, when the top sheet S1 is sent in the reverse direction -Q, the top sheet S1 is sandwiched between the feed roller 82 and the retard roller 84, and the second sheet S2 is sent in the reverse direction -Q beyond the position where it is sandwiched between the feed roller 82 and the retard roller 84, and is released from the feed roller 82 and the retard roller 84.

[0112] The above-mentioned distance of approximately 22 mm is one example of a distance sufficient to keep the top sheet S1 sandwiched between the feed roller 82 and the retard roller 84 while reliably separating the second sheet S2 from the feed roller 82 and the retard roller 84, and is not limited to a distance of approximately 22 mm; a distance of, for example, 10 to 25 mm can also be applied.

[0113] As described above, under the control of the control unit 90, the second sheet S2 falls into the sheet tray 20, and therefore, even if the feed roller 82 is rotated in the forward direction N in this state in which the hopper 21a is lowered, the second sheet S2 is not fed in the forward direction, and therefore continuous feeding does not occur. Therefore, under the control of the control unit 90, the printer 100 can eliminate the double feeding of the sheets S and prevent continuous feeding of the sheets S.

[0114] In this manner, the process in which the control unit 90 rotates the feed roller 82 in the reverse direction -N after the double feeding elimination process to move the second sheet S in contact with the retard roller 84 away from the retard roller 84 is hereinafter referred to as the continuous feeding prevention process.

[0115] (Vibration treatment) The control unit 90 then controls the hopper 21a to repeat the lifting and lowering operations at least once in succession, as shown in Fig. 5L. This lifting and lowering operation of the hopper 21a is an operation for reliably returning the second sheet S2 to the sheet tray 20.

[0116] That is, when the second sheet of paper S2 is sent in the reverse direction -Q by rotating the feed roller 82 in the reverse direction -N as shown in FIG. 5K, if the second sheet of paper S2 loses its propulsive force in the reverse direction -Q immediately after the leading end of the second sheet of paper S2 in the forward direction Q (rear end of the reverse direction -Q) leaves the retard roller 84, and if the leading end of the second sheet of paper S2 in the forward direction Q (rear end of the reverse direction -Q) stops with the leading end of the second sheet of paper S2 in the forward direction Q on the inclined portion 27a behind the retard roller 84, the second sheet of paper S2 will not return to the paper tray 20.

[0117] Then, when the front end of the second sheet S2 in the forward direction Q (rear end in the reverse direction -Q) is placed on the inclined portion 27a behind the retard roller 84, if the control unit 90 begins to control the feed roller 82 to rotate in the forward direction N, friction with the topmost sheet S1 may cause the second sheet S2 to move in the forward direction Q and come into contact with the retard roller 84 again, resulting in continued feeding.

[0118] Therefore, the control unit 90 vibrates all the sheets S on the hopper 21a by raising and lowering the hopper 21a, and this vibration causes the front end portion in the forward direction Q (rear end portion in the reverse direction -Q) of the second sheet S2 resting on the inclined portion 27a behind the retard roller 84 to slide off the inclined portion 27a, and the second sheet S2 is returned to the paper tray 20. In this way, the process in which the control unit 90 raises and lowers the hopper 21a to vibrate the sheets S after the continuous feeding prevention process is referred to as the vibration process below.

[0119] In addition, if the degree of gradient (inclination) of the inclined portion 27a of the inclined plate 27 with respect to the horizontal direction is set to such an extent that the second sheet of paper S reliably slides down the inclined portion 27a under its own weight immediately after the front end of the second sheet of paper S in the forward direction Q leaves the retard roller 84, the control unit 90 may omit the vibration process.

[0120] The degree of gradient (inclination) of the inclined portion 27a with respect to the horizontal direction, which allows the second sheet of paper S to reliably slide down the inclined portion 27a under its own weight immediately after the leading end of the second sheet of paper S in the forward direction Q leaves the retard roller 84, is preferably 25 degrees or more, as an example, and more preferably 35 degrees or more.

[0121] (Waiting process) After controlling the raising and lowering of the hopper 21a, the control unit 90 waits for a time of 200 [msec] to elapse. This wait time is set as the operation time until the second sheet S returns to the sheet tray 20 by raising and lowering the hopper 21a.

[0122] Therefore, if it is experimentally clear that the time it takes for the second sheet S to return to the sheet tray 20 after the hopper 21a is raised and lowered is shorter than 200 [msec], it may be set to shorter than 200 [msec], and if it is experimentally clear that the time is longer than 200 [msec], it may be set to longer than 200 [msec]. In this way, the process in which the control unit 90 waits without performing any operation for a predetermined time after the vibration process until the next process is started is hereinafter referred to as a standby process. Note that if the control unit 90 omits the vibration process, the standby process can also be omitted.

[0123] (Main paper feed processing) After waiting for 200 [msec], the control unit 90 rotates the feed roller 82 in the forward direction N while keeping the hopper 21a lowered, as shown in Fig. 5M, thereby eliminating the double feed and continuous feeding, and sends the top sheet S1 in the forward direction Q to the delivery path P1 in the same state as in Fig. 5G where no double feed is occurring. In this way, the process in which the control unit 90 again sends the sheet S1 in the forward direction Q to the delivery path P1 after the double feed elimination process and the continuous feeding prevention process is hereinafter referred to as the main paper feed process.

[0124] 5H to 5M are described as the processing when a multi-feed of paper S occurs, but since printer 100 does not have a means for detecting whether a multi-feed has occurred, control unit 90 always executes the multi-feed resolution processing and the continuous feed prevention processing as a series of processing regardless of whether a multi-feed has actually occurred. However, if printer 100 has a means for detecting whether a multi-feed has occurred, control unit 90 executes the multi-feed resolution processing and the continuous feed prevention processing only when it detects that a multi-feed has occurred, and if it does not detect that a multi-feed has occurred, control unit 90 can omit the multi-feed resolution processing and the continuous feed prevention processing.

[0125] In addition, if the printer 100 has a means for detecting whether or not continuous paper feeding is occurring, the control unit 90 executes the continuous paper feeding prevention process only when it detects that continuous paper feeding is occurring, and if it does not detect that continuous paper feeding is occurring, the control unit 90 can omit the continuous paper feeding prevention process.

[0126] In the explanation of the processing of the control unit 90 mentioned above, when the pickup roller 81 is rotated or stopped, the feed roller 82 also rotates or stops in synchronization with the pickup roller 81, and when the feed roller 82 is rotated or stopped, the pickup roller 81 also rotates or stops in synchronization with the feed roller 82; however, in order to avoid redundant explanation, the explanation is given as only the pickup roller 81 rotating or stopping, or only the feed roller 82 rotating or stopping.

[0127] As described above in detail, in the printer 100 of this embodiment, as shown in FIG. 6, the control unit 90 performs the sorting process, the looseness process, the double feed elimination process, the continuous feed prevention process, the vibration process, the standby process, and the main feed process. As a result, when the printer 100 sends the paper S from the paper tray 20 in the forward direction Q to the feed path P1, it is possible to eliminate, prevent or suppress double feeding, in which the paper S is sent overlapping, and to prevent or suppress continuous feeding, in which the next paper S2 is fed without leaving a specified gap after the previously sent paper S1.

[0128] (Retry processing) In the printer 100 of this embodiment, in the process of eliminating double feeds, the control unit 90 stops the rotation of the feed roller 82 in the forward direction N based on the result of detection by a paper sensor 92 provided in the pay-out path P1 of the front end portion of the paper S1 in the forward direction Q, which is sandwiched between the feed roller 82 and the retard roller 84, as shown in Figure 5I.

[0129] The paper sensor 92 is positioned 50 mm from the pickup roller 81. Therefore, as shown in FIG. 5F, by raising the hopper 21a, then rotating the pickup roller 81 in the forward direction N and feeding the paper S1 a distance of 50 mm in the forward direction Q, the paper sensor 92 should detect the leading end of the paper S1 in the forward direction Q.

[0130] However, if the control unit 90 controls the pickup roller 81 to raise the hopper 21a and then feed the paper S1 in the forward direction Q a distance exceeding 50 mm, and the paper sensor 92 does not detect the paper S1, it is considered that the pickup roller 81 did not feed the paper S1 normally during the double feed elimination process.

[0131] Therefore, in the process of eliminating double feeding, the control unit 90 raises the hopper 21a and then controls the pickup roller 81 and the feed roller 82 to rotate in the forward direction N and feed the paper S1 in the forward direction Q a distance exceeding 50 mm, for example a distance of 80 mm (see Figures 5E to 5I).If the paper sensor 92 still does not detect the paper S1, the pickup roller 81 and the feed roller 82 are stopped.

[0132] Then, the control unit 90 controls the hopper 21a to be lowered, and controls the pickup roller 81 and the feed roller 82 to be rotated in the reverse direction -N. This control returns the topmost sheet S1 (and the second sheet S2 in the case of multiple feeding) to a position in the reverse direction -Q from the pickup roller 81 and back to the paper tray 20, even if the leading edge of the topmost sheet S1 is in the forward direction Q relative to the positions of the feed roller 82 and the retard roller 84 and in front of the paper sensor 92.

[0133] Thereafter, the control unit 90 performs a vibration process of raising and lowering the hopper 21a one or more times to stabilize the paper S in the paper tray 20.

[0134] In this way, when the paper sensor 92 does not detect the paper S1 during the double feed resolution process, the control unit 90 rotates the pickup roller 81 and the feed roller 82 in the reverse direction -N to temporarily return the paper S to the paper tray 20 and further vibrates the hopper 21a. This process is called a retry process. The control unit 90 may omit the vibration process in the retry process.

[0135] Then, the printer 100 performs the above-mentioned sorting process, looseness process, double feed resolution process, subsequent paper feed prevention process, vibration process, standby process, and main paper feed process after the retry process by the control unit 90. This allows the printer 100 of this embodiment to return to normal processing after the double feed resolution process. The printer 100 may also omit the idle adjustment process, vibration process, and standby process that are performed after the retry process by the control unit 90. [Explanation of symbols]

[0136] 20 Paper Tray 21a Hopper (front part) 81 Pickup roller 82 Feed roller 84 Retard roller 90 Control section 92 Paper Sensor 100 Dye-sublimation thermal printer (printer) H Height direction L Anteroposterior direction W Width direction N Forward direction -N Reverse direction P1 Sheet feed path (feed path) Q Forward -Q reverse S Sheet (paper) S1 Top Paper S2 2nd sheet

Claims

1. A pickup roller and a feed roller that rotate synchronously and are fixed to the body of the printer; A paper tray that can store a large number of sheets and has a hopper that is a part of the bottom plate that can move up and down; a retard roller that contacts the feed roller and conveys the paper stored in the paper tray by pinching the paper between the feed roller and the retard roller when the paper tray is attached to the printer body; a control unit that controls operations of the pickup roller, the feed roller, and the hopper, The control unit is (1) rotating the pickup roller in a forward direction corresponding to the forward direction of the paper to feed the topmost sheet in the forward direction, and then sandwiching the topmost sheet between the feed roller and the retard roller and feeding it in the forward direction, thereby performing a double-feed elimination process in which a second sheet of paper that has been fed overlapping the topmost sheet is separated from the topmost sheet; (2) after the double feeding elimination process, the hopper is lowered and the feed roller is rotated in a reverse direction opposite to the normal rotation direction, thereby separating the second sheet from the retard roller and performing a continuous feeding prevention process; (3) A printer in which, after the continuous feeding prevention process, the feed roller is rotated in the forward direction to perform a main feeding process for feeding the topmost sheet.

2. Prior to the multiple feed resolution process, the control unit (0) A printer as described in claim 1, in which the hopper is lifted upward, the top sheet of paper contained in the paper tray is brought into contact with the pickup roller, and the pickup roller is rotated in a reverse direction corresponding to the opposite direction to the forward feed of the paper, thereby performing a separation process between the top sheet of paper and the second sheet of paper.

3. The control unit, after the continuous paper feed prevention process and before the main paper feed process, (4) The printer according to claim 1, further comprising a vibration process for raising and lowering the hopper.

4. The control unit, after the vibration process and before the main paper feeding process, (5) The printer according to claim 3, further comprising a standby process for waiting for a predetermined period of time without performing any operation.

5. The control unit, after the sorting process and before the double feed elimination process, (6) The printer according to claim 2, further comprising a play adjustment process for rotating the pickup roller and the feed roller idly in the forward rotation direction while the hopper is lowered.

6. a paper sensor for detecting a front end of the paper fed in the forward direction by being sandwiched between the feed roller and the retard roller; When the paper sensor does not detect the leading edge of the top sheet of paper in a state where the top sheet of paper is sandwiched between the feed roller and the retard roller and fed a predetermined distance in the forward direction in the double feeding elimination process, (7) A printer as described in any one of claims 1 to 5, which performs a retry process by stopping rotation of the feed roller, lowering the hopper downward, and rotating the feed roller in the reverse direction to return the topmost sheet to the paper tray, and then performs the double feed elimination process, the continuous paper feed prevention process, and the main paper feed process.

7. The printer according to claim 6 , wherein the control unit adds a vibration process for raising and lowering the hopper after the topmost sheet is returned to the sheet tray in the retry process.

8. a paper sensor for detecting a front end of the paper fed in the forward direction by being sandwiched between the feed roller and the retard roller; When the paper sensor does not detect the leading edge of the top sheet of paper in a state where the top sheet of paper is sandwiched between the feed roller and the retard roller and fed a predetermined distance in the forward direction in the double feeding elimination process, (7) A printer as described in claim 1, which performs a retry process by stopping rotation of the feed roller, lowering the hopper, and rotating the feed roller in the reverse direction to return the topmost sheet to the paper tray, and then performs the double feed resolution process, the continuous paper feed prevention process, and the main paper feed process.

Images