Printer

Abstract

To provide a printer which is configured to prevent a direction in which paper is fed from greatly varying due to a retard roller swing in an allowable range of an insertion depth for a paper tray with respect to a main body of the printer.SOLUTION: A printer 100 comprises: a pick-up roller 81 and a feed roller 82 which are fixed to a main body thereof; a paper tray 20 which is detachably attached thereto; and a retard roller 84 that come into contact with the feed roller 82 in a state where the paper tray 20 is attached thereto and conveys stored paper S by sandwiching the paper between itself and the feed roller 82. The retard roller 84 has: a base member 84d fixed to a lower portion at a front part of the paper tray 20; a roller member 84b that comes into contact with the feed roller 82; and a swinging arm member 84a that rotatably supports the roller member 84b at an upper end part thereof, has a lower end part formed to be rotatable in a longitudinal direction with respect to the base member 84d, is arranged in a posture extending in a heigh direction H, and swings forward when the roller member 84b is pressed by the feed roller 82.SELECTED DRAWING: Figure 4A

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] In order to eliminate the double feeding, a retard roller is arranged to face the feed roller and sandwich the paper between the feed roller and the retard roller. In this case, the torque of the feed roller is applied to the topmost paper in contact with the feed roller, so the topmost 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 that has advanced overlapping the topmost sheet is stopped by the torque of the retard roller and separated from the topmost sheet, eliminating the double feeding (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6035312 Summary of the Invention [Problem to be solved by the invention]

[0006] Here, the pressure at which the feed roller and the retard roller come into contact needs to be within a predetermined range; however, in a printer in which the feed roller is located in the printer body and the retard roller is located in the paper tray, the pressure at which the feed roller and the retard roller come into contact will vary depending on the depth to which the paper tray is inserted into the main body, so it is desirable for the depth to which the paper tray is inserted into the main body to be constant.

[0007] However, even if the insertion depth of the paper tray into the main body varies slightly due to manufacturing errors or handling convenience of the printer, the printer will operate normally. In other words, even if the insertion depth of the paper tray into the main body is small, as long as the small depth is within a certain range, the printer will operate normally in the same way as when the insertion depth is the specified depth.

[0008] For this reason, the retard roller is configured so that the contact pressure does not vary significantly even if the contact position with the feed roller changes and the swing angle changes. Moreover, the printer is required to ensure that the direction of the common tangent at the contact position between the feed roller and the retard roller does not vary significantly due to the swing of the retard roller within the allowable range of the insertion depth of the paper tray into the main body (the range in which the printer operates normally).

[0009] The present invention has been developed in consideration of the above-mentioned circumstances, and aims to provide a printer in which the direction of the common tangent between the feed roller and the retard roller does not change significantly due to oscillation of the retard roller within the allowable range of the insertion depth of the paper tray into the main body. [Means for solving the problem]

[0010] The present invention is a printer comprising a feed roller fixed to the printer body, and a paper tray containing a large number of sheets of paper that is removably attached to the printer body, and has a retard rotor that contacts the feed roller when the paper tray is attached to the printer body and transports the paper contained in the paper tray by clamping it between the feed roller and the feed roller, and the retard roller has a base member fixed to the lower front part of the paper tray, a roller member that contacts the feed roller, and a swinging arm member that rotatably supports the roller member at its upper end and is rotatable back and forth relative to the base member, is arranged in a vertically extending position, and swings forward when the roller member comes into contact with the feed roller. Effect of the Invention

[0011] The printer according to the present invention prevents the direction of the common tangent line between the feed roller and the retard roller from fluctuating significantly due to oscillation of the retard roller within the allowable range of the insertion depth of the paper tray into the main body. [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 4A] 1 for explaining the structures and functions of a pickup roller, a feed roller, and a retard roller; FIG. [Figure 4B] 1 for explaining the structures and functions of a pickup roller, a feed roller, and a retard roller; FIG. [Diagram 5] FIG. [Figure 6] FIG. 4 is a cross-sectional view showing the inside of the retard roller. [Figure 7A] FIG. 13 is a perspective view (part 1) illustrating a configuration for generating a torque difference of a retard roller. [Figure 7B] FIG. 13 is a perspective view (part 2) illustrating a configuration for generating a torque difference in the retard roller. [Figure 8A] 4A, which explains the structure and operation of a comparative example in which a roller member of a retard roller is swung up and down around an axis at the front end of a swing arm member that extends rearward in the front-to-rear direction from in front of the roller member. [Figure 8B] 4B, which explains the structure and operation of a comparative example in which a roller member of a retard roller is swung up and down around an axis at the front end of a swing arm member that extends rearward in the front-to-rear direction from in front of the roller member. [Figure 9] FIG. 4 is a perspective view showing the positional relationship between a paper tray and a paper guide. [Figure 10] 4 is a plan view showing the positional relationship between a paper tray and a paper guide. FIG. [Figure 11A] 11 is a cross-sectional view showing a vertical cross section taken along line AA in FIG. 10. [Figure 11B] 11 is a cross-sectional view showing a vertical cross section taken along line BB in FIG. 10. [Figure 11C] 11 is a cross-sectional view showing a vertical cross section taken along line CC in FIG. 10. [Figure 11D] 11 is a cross-sectional view showing a vertical cross section taken along line DD in FIG. 10. 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 of a width direction W and along a front-rear direction L of a dye-sublimation thermal printer 100 (hereinafter referred to as 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 of 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. When removed from the main body of the printer 100, the paper tray 20 is attached to the main body of the printer 100 as shown in FIG. 1. The detailed structure of the paper tray 20 will be described later.

[0019] <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.

[0020] <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).

[0021] 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.

[0022] 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.

[0023] <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.

[0024] <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.

[0025] <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.

[0026] 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.

[0027] 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.

[0028] When the paper S is fed, the hopper 21a of the paper tray 20 is raised, and the action of feeding the paper S will be described later together with the structure of the retard roller 84.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] <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 mainly composed of a drive roller driven by a motor (not shown) controlled by the control unit 90, a driven roller having no driving force, and switching members 71, 72, and 73 that switch the conveying path P.

[0038] Of the conveying means 70, illustrations and descriptions are omitted for a roller pair consisting of a normal drive roller and driven roller 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, which will be described later. The pickup roller 81, the feed roller 82, and the retard roller 84 will be described later.

[0039] 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.

[0040] The switching member 72 is provided at the rear end of the printing path P3. The switching member 72 serves as a switching valve that returns the paper S sent in the reverse direction -Q on the printing path P3 to the downstream printing path P5 without accidentally entering the roll paper feed path P8. The switching member 72 is biased by a spring toward the side that blocks the roll paper feed path P8.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] <Control Unit> The control unit 90 is disposed above the paper tray 20 and behind the printing unit 30. The control unit 90 controls the operations of the printing unit 30, the cutter unit 40, the creasing unit 50, and the conveying means .

[0048] [Printer Operation Overview] <For 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 paper S stored in the paper tray 20 is fed in the forward direction Q along the feed path P1, then sent in the forward direction Q along the paper feed path P2, then sent in the forward direction Q along the print path P3, and then sent in the forward direction Q along the standby path P4.

[0049] The paper S is then fed in the reverse direction -Q along the waiting path P4, and then fed in the reverse direction -Q along the printing path P3 while being printed on one side (the side facing the thermal head 31) in the printing section 30. When performing multi-color printing on the paper S in the printing section 30 or coating after printing, the paper S is repeatedly fed in the forward direction Q and the reverse direction -Q along the printing path P3 and the waiting path P4.

[0050] The paper S printed in the printing unit 30 is then sent in a forward direction Q (corresponding to the reverse direction -Q in the printing path P3) through the printing downstream path P5, then sent in the forward direction Q through the reversal waiting path P6, then sent in the forward direction Q of the paper feed path P2, and then sent in the forward direction Q through the printing path P3. As described above, the paper S is reversed upside down by passing through the reversal waiting path P6 and the paper feed path P2.

[0051] When the printer 100 finishes printing only on one side of the paper S, the paper S is then sent in the forward direction Q along the discharge path P9 and is discharged from the discharge opening 15 to the outside of the printer 100, where the printing is completed.

[0052] When the printer 100 prints on both sides of the paper S, the paper S is fed in the forward direction Q along the printing path P3, and is then fed in the forward direction Q along the waiting path P4.

[0053] The paper S is then fed in the reverse direction -Q along the waiting path P4, and then fed in the reverse direction -Q along the printing path P3 while being printed on the other side (the side facing the thermal head 31) in the printing section 30. When performing multi-color printing on the paper S in the printing section 30 or coating after printing, the paper S is repeatedly fed in the forward direction Q and the reverse direction -Q along the printing path P3 and the waiting path P4.

[0054] The paper S printed in the printing section 30 is then sent in the forward direction Q through the printing lower path P5, then sent in the forward direction Q through the reversal waiting path P6, then sent in the forward direction Q of the paper feed path P2, then sent in the forward direction Q through the printing path P3, then sent in the forward direction Q through the discharge path P9, and is finally discharged outside the printer 100 from the discharge outlet 15.

[0055] When creasing is performed on the printed paper S, in the case of single-sided printing, when the paper S after single-sided printing is in the reversing waiting path P6, it is sent in the reverse direction -Q through the reversing waiting path P6, and then sent in the reverse direction -Q through the creasing path P7, where it is creasingly performed at the creasing section 50.

[0056] When creasing is performed on the printed paper S, in the case of double-sided printing, when the paper S after double-sided printing is in the reversing waiting path P6, it is sent in the reverse direction -Q through the reversing waiting path P6, and then sent in the reverse direction -Q through the creasing path P7, where it is creasingly performed at the creasing section 50.

[0057] <For 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 paper R stored in the roll paper storage unit 60 is unwound in the forward direction Q along the roll paper feed path P8. As the roll paper R is unwound, it is unwound from the roll.

[0058] The paper R is then fed in the forward direction Q along the print path P3 and then fed in the forward direction Q along the standby path P4.

[0059] The paper R is then returned in the reverse direction -Q along the waiting path P4, and then returned in the reverse direction -Q along the printing path P3, while being printed on one side (the side facing the thermal head 31) in the printing section 30. When the paper R is returned in the reverse direction -Q, it is rewound onto the roll.

[0060] When performing multi-color printing on the paper R in the printing section 30 or when performing coating after printing, forward feeding in the Q direction and reverse feeding in the −Q direction are repeatedly performed on the printing path P3 and the waiting path P4.

[0061] The paper R printed in the printing section 30 is then fed in the forward direction Q along the printing path P3, and then fed in the forward direction Q along the discharge path P9, where it is cut to a predetermined length by the cutter section 40. The printed paper R, which has been separated from the roll by the cutting, is then discharged outside the printer 100 through the discharge opening 15.

[0062] The portion of paper R where the printed portion has been cut off and connected to the roll is rewound onto the roll in roll paper storage section 60, and is returned in the reverse direction -Q via discharge path P9, printing path P3, and roll paper feed path P8.

[0063] [Retard roller and paper tray] Figures 4A and 4B are partial cross-sectional views equivalent to Figure 1 for explaining the structure and function of pickup roller 81, feed roller 82, and retard roller 84, Figure 5 is an oblique view showing retard roller 84, Figure 6 is a cross-sectional view showing the inside of retard roller 84, and Figures 7A and 7B are exploded oblique views explaining the configuration that generates a torque difference in the retard roller.

[0064] Note that Figure 4A shows the paper tray 20 installed in the correct position (reference position) in the front-to-back direction L relative to the main body of the printer 100, and Figure 4B shows the paper tray 20 installed in a position closer to the reference position (a position forward in the front-to-back direction L relative to the reference position).

[0065] 7A shows the retard roller 84 as viewed from below on the outside in the width direction W, and FIG. 7B shows the retard roller 84 as viewed from above on the inside in the width direction W.

[0066] 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.

[0067] 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-to-rear direction L. The arm 83 is also positioned in an inclined position overall 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 pressing the pickup roller 81 against the paper S stored in the paper tray 20.

[0068] The pickup roller 81 and the feed roller 82 are driven by a single motor, so that the pickup roller 81 and the feed roller 82 rotate and stop in synchronization with each other, and when they rotate, they rotate in the same direction.

[0069] <Paper tray details> 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.

[0070] The front portion 21a of the bottom plate 21 is formed so as to be able to swing upward around the rear end of the front portion 21a as an axis C3. In other words, the front portion 21a is a hopper that lifts up the front portion of the paper S placed on the bottom plate 21 when tilted upward. Hereinafter, this front portion 21a will be referred to as the hopper 21a. The hopper 21a is moved up and down by the drive of a motor (not shown) provided in the main body of the printer 100. The motor that moves the hopper 21a up and down is driven under the control of the control unit 90.

[0071] 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 has a rearward downward inclination. An opening 27d is formed in the center of the inclined plate 27 in the width direction W. The inclined plate 27 will be described in more detail later.

[0072] 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.

[0073] The paper tray 20, which has been pulled out forward in the front-to-rear direction L 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 rearward (in the opposite direction to 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.

[0074] 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 above the surface of the inclined plate 27 through an opening 27d formed in the inclined plate 27.

[0075] When paper S is to be fed from the paper tray 20, a plate 19 (see Figures 1, 4A, and 4B) which is provided in the main body of the printer 100 and operates under the control of the control unit 90 pushes up the hopper 21a from an opening 20A (see Figure 1) formed in the underside of the paper tray 20, causing the hopper 21a to be lifted upward and assume an inclined position (shown by a dotted line in Figure 2).

[0076] Hopper 21a is configured to tilt upward so that, regardless of the number of sheets of paper S contained in paper tray 20, the topmost sheet of paper S lifted by hopper 21a hits pickup roller 81, lifting pickup roller 81, and the extension of the leading edge of that sheet of paper S hits the rear end of inclined plate 27 without touching feed roller 82, as shown in Figures 4A and 4B.

[0077] 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. 4A, 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 contact the feed roller 82 fixed to the main body of the printer 100.

[0078] <Retard roller> (composition) The retard roller 84 is a driven roller and is not driven, but the paper S is sandwiched between the driven feed roller 82 and the non-driven retard roller 84, and the feed roller 82 is driven to transport the paper S to the delivery path P1.

[0079] As shown in FIG. 5 in detail, the retard roller 84 includes a base member 84d, two swing arm members 84a, a roller member 84b, and two coil springs 84c.

[0080] 4A, the base member 84d is disposed in the front space between the front panel 22 and the front cover member 26, and is fixed to the lower part of the paper tray 20. The base member 84d has a vertical wall 84k extending upward in the height direction H from its front part.

[0081] The roller member 84b is a substantially cylindrical roller that comes into contact with the feed roller 82. The detailed structure of the roller member 84b will be described later, but when the roller member 84b rotates around the axis C2, it generates a torque in the opposite direction (a torque opposite to the direction of rotation) to brake the rotation.

[0082] The swing arm member 84a is a long, narrow plate-like member that supports the roller member 84b on the base member 84d. The swing arm member 84a is disposed in a position such that its longitudinal direction is along the height direction H of the printer 100. The swing arm members 84a are disposed at both ends in the axis C2 direction of the roller member 84b, which is disposed in a position such that the axis C2 is along the width direction W of the printer 100, so as to be perpendicular to the axis C2.

[0083] The swing arm member 84a supports the roller member 84b at one end (upper end) on the upper side in the longitudinal direction so as to be rotatable about an axis C2, and is supported by the base member 84d at one end (lower end) on the lower side in the longitudinal direction so as to be rotatable about an axis C1 parallel to the axis C2. As a result, the swing arm member 84a is supported so as to be swingable back and forth about the axis C1 relative to the base member 84d, as shown by the black arrow in Fig. 5, and swings the roller member 84b back and forth.

[0084] The coil spring 84c has one end in contact with the swing arm member 84a and the other end in contact with the vertical wall 84k, and is disposed between the swing arm member 84a and the vertical wall 84k along the front-rear direction L. As a result, the coil spring 84c presses the swing arm member 84a toward the rear of the swingable range.

[0085] Therefore, when there is no obstacle restricting the position of the roller member 84b, the retard roller 84 is biased by the elastic force of the coil spring 84c and is positioned at the rear of the swingable range. On the other hand, when there is a member or the like against which the roller member 84b abuts in front, the swing arm member 84a swings to contract the coil spring 84c, and the retard roller 84 is displaced forward within the swingable range.

[0086] (Basic function of retard roller to eliminate double feeding) The retard roller 84 configured as described above operates together with the feed roller 82 as follows.

[0087] As shown in Fig. 4A, the paper tray 20 containing the paper S is attached to the main body of the printer 100 at a reference position in the front-rear direction L. At this time, the feed roller 82 fixed to the main body of the printer 100 abuts against the upper rear portion of the roller member 84b of the retard roller 84 of the paper tray 20, and the roller member 84b is pressed downward and forward.

[0088] As a result, the oscillating arm member 84a supporting the roller member 84b is pushed forward within its swing range, and the coil spring 84c is elastically deformed by the pushing load, so that the retard roller 84 is in a state in which the oscillating arm member 84a is displaced forward within its swing range.

[0089] Then, under the control of the control unit 90, the hopper 21a is lifted, and the topmost sheet S of the sheets S (hereinafter, referred to as the topmost sheet S) is pressed against the pickup roller 81.

[0090] Next, under the control of the control unit 90, a motor (not shown) rotates forward, and the pickup roller 81 and the feed roller 82 rotate forward. The forward rotation direction of the pickup roller 81 and the feed roller 82 is the direction in which the paper S is fed in the forward direction Q through the payout path P1.

[0091] When the pickup roller 81 rotates forward, the topmost sheet S pressed against the pickup roller 81 receives the torque of the forward rotation of the pickup roller 81 and is sent in the forward direction Q. When the topmost sheet S is sent in the forward direction Q, the leading edge of the sheet S hits the rear end of the inclined plate 27, but because the leading edge of the sheet S is inclined upward, the sheet S bends so that the leading edge of the sheet S escapes to the upper side of the inclined plate 27. Then, the leading edge of the sheet S comes into contact with the retard roller 84, which is rotating forward in response to the feed roller 82, and is further sandwiched between the feed roller 82 and the retard roller 84.

[0092] Here, if the second sheet of paper S is fed overlapping the topmost sheet of paper S, the leading edge of the topmost sheet of paper S will hit the rear end of the inclined plate 27 and bend upward to escape, but since the second sheet of paper S is unlikely to bend at the same time as the topmost sheet of paper S, this has the effect of making it difficult for the second sheet of paper S to reach the retard roller 84.

[0093] When the top sheet S is sandwiched between the feed roller 82 and the retard roller 84, the top sheet S is sent to the delivery path P1 at a delivery angle θ1, which is the direction of a common tangent M between the feed roller 82 and the retard roller 84 with respect to the horizontal direction. Then, when the top sheet S has been sent a certain distance to the delivery path P1, the hopper 21a is lowered to its original position under the control of the control unit 90. As a result, the pickup roller 81 moves away from the top sheet S.

[0094] Here, as described above, the roller member 84b of the retard roller 84 generates an initial torque in the opposite direction to the rotation direction so as to brake the rotation, whether it rotates in the forward direction N or in the reverse direction -N. Therefore, it operates as follows with respect to the paper S sandwiched between it and the feed roller 82.

[0095] First, when only one regular sheet of paper S is fed by the pickup roller 81, that is, when only the topmost sheet of paper S is fed, only the topmost sheet of paper S is sandwiched between the feed roller 82 and the retard roller 84. Since the feed roller 82 is rotating in the forward direction, a propulsive force is applied to the top surface of the topmost sheet of paper S in the forward direction Q due to friction with the feed roller 82.

[0096] On the other hand, the underside of the topmost sheet of paper S is in contact with the retard roller 84, and when the topmost sheet of paper S moves in the forward direction Q, it attempts to rotate the retard roller 84 in the forward direction N. However, since the retard roller 84 is subjected to an initial torque in the opposite direction to the direction of rotation (forward direction N) as described above, a braking force in the opposite direction to the propulsion force in the forward direction Q acts on the underside of the topmost sheet of paper S.

[0097] Here, the initial torque of the retard roller 84 in the direction opposite to the forward rotation direction N is set to be smaller than the forward rotation torque of the feed roller 82, so that the topmost sheet S is sent in the forward direction Q along the payout path P1 by the propulsion force of the feed roller 82, regardless of the braking force received from the retard roller 84.

[0098] Next, we will explain what happens when the paper S fed by the pickup roller 81 is double-fed, that is, when a second sheet of paper S in contact with the topmost sheet of paper S is attracted to the topmost sheet of paper S due to static electricity or the like and is fed out together with the topmost sheet of paper S.

[0099] When double feeding occurs, the top sheet S and the second sheet S are sandwiched in an overlapping state between the feed roller 82 and the retard roller 84. The top surface of the top sheet S in contact with the feed roller 82 is subjected to a propulsive force that sends the sheet S in the forward direction Q due to friction with the feed roller 82 caused by the sheet S being sandwiched between the retard roller 84 and the feed roller 82.

[0100] When the top sheet of paper S moves in the forward direction Q, the second sheet of paper S tries to move in the forward direction Q using the frictional force with the top sheet of paper S as a driving force. However, since the bottom surface of the second sheet of paper S is in contact with the retard roller 84 and an initial torque is applied to the retard roller 84 in the opposite direction to the rotational direction, a braking force in the opposite direction to the driving force in the forward direction Q by the retard roller 84 acts on the bottom surface of the second sheet of paper S.

[0101] Here, the propulsive force acting on the second sheet S in the forward direction Q is a frictional force with the topmost sheet S, and this frictional force is considerably smaller than the propulsive force acting on the topmost sheet S due to the torque of the feed roller 82, and does not exceed the braking force received from the retard roller 84. As a result, the topmost sheet S is sent in the forward direction Q along the delivery path P1, but the second sheet S is held stopped between the feed roller 82 and the retard roller 84.

[0102] As a result, the top sheet S can be separated from the second sheet S and fed to the feeding path P1.

[0103] (Action by swing arm member) In the printer 100 of this embodiment, the roller member 84b of the retard roller 84 is swung by a swing arm member 84a extending in the height direction H, with the axis C1 at the lower end of the swing arm member 84a as the rotation fulcrum. Therefore, compared to a printer in which the roller member 84b of the retard roller 84 is swung up and down by a swing arm member extending in the front-to-rear direction L from forward of the roller member 84b, with the axis at the front end of the swing arm member as the rotation fulcrum, the printer 100 can reduce fluctuations in the pay-out direction of the paper S in response to a shift in the installation position of the paper tray 20 in the front-to-rear direction L.

[0104] That is, the paper tray 20 is inserted in the front-to-rear direction L into the main body of the printer 100 and installed at a reference position, but the printer 100 is configured to operate normally even if the insertion depth of the paper tray 20 into the main body of the printer 100 varies slightly due to manufacturing errors in the printer 100 or for convenience in handling the printer 100.

[0105] In order for printer 100 to feed paper S normally and to eliminate double feeding, it is necessary to keep the contact pressure between feed roller 82 and retard roller 84 within a predetermined range. Therefore, regardless of the insertion depth of paper tray 20 into the main body of printer 100, when roller member 84b of retard roller 84 comes into contact with feed roller 82, swing arm member 84a swings to change the position of roller member 84b, thereby absorbing the fluctuation in the contact pressure between feed roller 82 and roller member 84b of retard roller 84.

[0106] Here, when the paper tray 20 is positioned (see FIG. 4B) in a position in front of the printer 100 body in the front-to-rear direction L (a position forward of the reference position in the front-to-rear direction L) the reference position (FIG. 4A), the portion of the roller member 84b that contacts the feed roller 82 is higher and forward than in the reference position.

[0107] Therefore, the amount of displacement by which the swing arm member 84a swings forward becomes smaller than that in the reference position, and the payout angle θ2 of the common tangent line M between the feed roller 82 and the roller member 84b of the retard roller 84 becomes larger than the payout angle θ1 of the common tangent line M in the reference position. The common tangent line M is the direction (payout direction) of the paper S that is sandwiched between the feed roller 82 and the roller member 84b of the retard roller 84 and paid out to the payout path P1.

[0108] According to an experiment, the feed angle θ1 was, for example, 49.49 degrees, and the feed angle θ2 was, for example, 50.12 degrees. In other words, the variation Δθ in the feed direction of the paper S according to the shift in the front-rear direction L of the mounting position of the paper tray 20 is, for example, 0.63 (=50.12-49.49) degrees.

[0109] 8A and 8B are diagrams for explaining the structure and operation of a comparative example in which a roller member 84b of a retard roller 84 is swung up and down around an axis C4 at the front end of a swing arm member 84a' as a rotation fulcrum by a swing arm member 84a' that extends rearward in the front-to-rear direction L from in front of the roller member 84b. Fig. 8A shows a state corresponding to Fig. 4A in which the paper tray 20 is placed in a normal position (reference position) on the main body of the printer 100, and Fig. 8B shows a state corresponding to Fig. 4B in which the paper tray 20 is placed in a position forward of the reference position (a position forward in the front-to-rear direction L from the reference position).

[0110] As shown in Figures 8A and 8B, the roller member 84b of the retard roller 84 is supported on the rear end of a swing arm member 84a' extending in the front-to-rear direction L from in front of the roller member 84b, and the swing arm member 84a' swings up and down around the axis C4 at the front end as a rotation fulcrum. In this comparative example, the movement of the roller member 84b is described.

[0111] 8A, in the state where the paper tray 20 is inserted into the reference position of the main body of the printer 100, when the upper rear part of the retard roller 84 hits the feed roller 82, the swing arm member 84a' of the retard roller 84 assumes a position displaced downward within the swing range around the axis C4. In this state, the payout angle of the common tangent M of the feed roller 82 and the retard roller 84 is θ1'.

[0112] On the other hand, in the comparative example, as shown in Fig. 8B, when the paper tray 20 is placed in a position in front of the reference position (Fig. 8A) of the main body of the printer 100 in the front-to-rear direction L (a position forward of the reference position in the front-to-rear direction L), the portion of the retard roller 84 that contacts the feed roller 82 is located forward and above than when it is at the reference position. Note that the state in which the paper tray 20 in the comparative example is placed in a position in front of the reference position of the main body of the printer 100 in the front-to-rear direction L is set to the same conditions as the state in the printer 100 of this embodiment shown in Fig. 4B.

[0113] In this case, the payout angle θ2' of the common tangent M between the feed roller 82 and the retard roller 84 becomes larger than the payout angle θ1' of the common tangent M between the feed roller 82 and the retard roller 84 in the reference position. According to an experiment, the payout angle θ1' is, for example, 51.83 degrees, and the payout angle θ2' is, for example, 59.87 degrees. In other words, the variation Δθ' in the payout direction of the paper S according to the deviation of the mounting position of the paper tray 20 in the front-rear direction L is, for example, 8.04 (=59.87-51.83) degrees.

[0114] In this way, in the printer 100 of this embodiment, the retard roller 84 is structured to swing the roller member 84b back and forth by the swing arm member 84a extending along the height direction H, so that the fluctuation Δθ in the pay-out direction of the paper S in response to a shift in the mounting position of the paper tray 20 in the front-to-rear direction L can be reduced compared to the comparative example in which the retard roller 84 is structured to swing the roller member 84b up and down by the swing arm member 84a' extending along the front-to-rear direction L.

[0115] As a result, in the printer 100 of this embodiment, regardless of the misalignment of the mounting position of the paper tray 20 in the front-to-rear direction L, the fluctuation Δθ in the payout direction of the paper S is small, so that the paper S paid out to the payout path P1 is prevented from getting caught on the surrounding walls (especially the inner walls) that separate the payout path P1, and the risk of the paper S becoming jammed in the payout path P1 is reduced.

[0116] Note that the fact that the oscillating arm member 84a of the printer 100 of this embodiment is longer than the oscillating arm member 84a' of the comparative example is one factor that causes the printer 100 of this embodiment to have a smaller fluctuation Δθ in the pay-out direction of the paper S than the comparative example, but the main factor that reduces the fluctuation Δθ in the pay-out direction is the structure that causes the oscillating arm member 84a to swing back and forth.

[0117] In addition, the printer 100 of this embodiment reduces the fluctuation Δθ in the payout direction of the paper S that occurs in response to a shift in the front-to-rear direction L of the mounting position of the paper tray 20 by orienting the oscillating arm member 84a in a position along the height direction H, but the effect of reducing the fluctuation Δθ in the payout direction of the paper S is not limited to the roller member 84b supported by the oscillating arm member 84a functioning as a retard roller 84.

[0118] That is, in a printer in which the orientation of the swing arm member 84a is oriented along the height direction H, even if the roller member 84b supported by the swing arm member 84a is a simple driven roller that does not apply an initial torque (braking) in the direction opposite to the rotation direction, it is possible to reduce the variation Δθ in the pay-out direction of the paper S that corresponds to a deviation in the mounting position of the paper tray 20 in the front-to-rear direction L. Therefore, in a printer in which the orientation of the swing arm member 84a is oriented along the height direction H, the roller member 84b supported by the swing arm member 84a may be a simple driven roller.

[0119] (Detailed structure of the retard roller and its function during reverse rotation) The basic action of the retard roller 84 to eliminate double feeding is as described above, but if the feed roller 82 continues to rotate in the forward direction after the rear end of the top sheet S in the forward direction Q leaves the feed roller 82, the torque of the feed roller 82 acts on the second sheet S that is stopped in contact with the retard roller 84, and the second sheet S is fed out to the feed path P1. In this case, the second sheet S is fed out with almost no gap between it and the top sheet S fed out to the feed path P1, resulting in continuous feeding.

[0120] In order to avoid such continuous feeding, after the leading edge of the top sheet S has been fed into the feed path P2 following the feed path P1, the control unit 90 drives another drive roller (one of the conveying means 70: not shown) provided in the feed path P2 to feed the top sheet S in the forward direction Q while stopping the feed roller 82, thereby preventing the second sheet S from being fed continuously.

[0121] However, when the printer 100 is configured to drive the separate drive roller provided in the paper feed path P2 and the feed roller 82 with a single motor, it is not possible to drive only the separate drive roller provided in the paper feed path P2 and stop the feed roller 82.

[0122] Therefore, in the printer 100, the control unit 90 reverses the feed rollers 82 before the trailing end of the top sheet S in the forward direction Q leaves the feed rollers 82. In other words, at this time, the leading ends of the top sheet S and the second sheet S in the forward direction Q are misaligned.

[0123] Therefore, by rotating the feed roller 82 in the reverse direction, the topmost sheet S and the second sheet S overlapping it are moved back together toward the paper tray 20. As a result, the second sheet S, whose leading edge in the forward direction Q is positioned backward, leaves the position sandwiched between the feed roller 82 and the retard roller 84 before the topmost sheet S, and only the second sheet S can be returned to the paper tray 20.

[0124] However, if the retard roller 84 is configured to simply generate a torque (reverse torque) in the direction opposite to the direction of rotation, due to the same action as when it rotates in the forward direction described above, the retard roller 84 will send only the top sheet of paper S in the reverse direction -Q, leaving the second sheet of paper S stopped, and it will not be possible to return only the second sheet of paper S to the paper tray 20 as expected.

[0125] Therefore, in the printer 100 of this embodiment, the retard roller 84 generates different counter torques when rotating in the forward direction and when rotating in the reverse direction. The detailed structure of the retard roller 84 that generates the different counter torques will be described below.

[0126] (Detailed structure) 6, 7A, and 7B, the roller member 84b includes a rubber roller 84e, a housing 84f, an inner ring 84g, a first torque spring 84h, and a torque spring 84i. The first torque spring 84h and the torque spring 84i are wound in the same direction around the inner ring 84g.

[0127] The rubber roller 84e is provided in close contact with the outer peripheral surface of the housing 84f, and the rubber roller 84e and the housing 84f rotate together. The inner ring 84g has a portion 84g1 (hereinafter referred to as the first portion 84g1) on one end side in the axial direction disposed inside the housing 84f, and a portion 84g2 (hereinafter referred to as the second portion 84g2) on the other end side in the axial direction protruding outward from an end of the housing 84f in the width direction W and disposed inside the swing arm member 84a. The inner ring 84g is rotatable relative to the housing 84f and the swing arm member 84a.

[0128] The first torque spring 84h is arranged so as to be wound around the outer peripheral surface of the first portion 84g1 of the inner ring 84g, with one end rising outward in the radial direction and fixed to the inner peripheral surface of the housing 84f. The second torque spring 84i is arranged so as to be wound around the outer peripheral surface of the second portion 84g2 of the inner ring 84g, with one end rising outward in the radial direction and fixed to the inner peripheral surface of the swing arm member 84a.

[0129] The first torque spring 84h and the second torque spring 84i have their coils wound in the same direction, and the wire diameter of the spring forming the first torque spring 84h is thicker than the wire diameter of the spring forming the second torque spring 84i.

[0130] The operation of the roller member 84b when it rotates about the axis C2 relative to the swing arm member 84a will be described. When the housing 84f and the rubber roller 84e attempt to rotate in the normal direction N about the axis C2 relative to the swing arm member 84a, one end 84h1 of the first torque spring 84h attempts to rotate in the normal direction N together with the housing 84f because one end 84h1 of the first torque spring 84h is fitted into the groove 84f1 of the housing 84f.

[0131] Here, since the first torque spring 84h is wound around the first portion 84g1 of the inner ring 84g, in order for one end 84h1 of the first torque spring 84h to rotate in the forward rotation direction N, the first torque spring 84h must rotate in the forward rotation direction N together with the inner ring 84g, or only the one end 84h1 of the first torque spring 84h must rotate in the forward rotation direction N. When the inner ring does not rotate and only the one end 84h1 of the first torque spring 84h rotates in the forward rotation direction N, the first torque spring 84h is elastically deformed in a direction in which the winding diameter of the first torque spring 84h increases. Therefore, even if the inner ring 84g does not rotate in the forward rotation direction N, the rotation of the housing 84f and the rubber roller 84e in the forward rotation direction N is not hindered.

[0132] If the inner ring 84g were to rotate in the normal direction N together with the first torque spring 84h, the second portion 84g2, which is a part of the inner ring 84g, would also rotate in the normal direction N. Since the second torque spring 84i is wound around the second portion 84g2, the second torque spring 84i would also rotate in the normal direction N. However, since one end 84i1 of the second torque spring 84i is fitted and fixed in a groove 84a1 formed in the inner peripheral surface of the swing arm member 84a, the one end 84i1 of the second torque spring 84i does not rotate. In this case, the second torque spring 84i needs to elastically deform in a direction that reduces the winding diameter.

[0133] However, when the winding diameter of the second torque spring 84i is reduced, the second torque spring 84i is wound around the outer circumferential surface of the second portion 84g2 with increased force, and the second portion 84g2 does not slip relative to the second torque spring 84i. Therefore, the inner ring 84g does not rotate in the forward rotation direction N, and remains stopped.

[0134] By the above-mentioned operation, one end of the first torque spring 84h tries to rotate integrally with the housing 84f in the forward rotation direction N, but the first portion 84g1 around which the first torque spring 84h is wound does not rotate. In order for the housing 84f to rotate in the forward rotation direction N, a torque is required that elastically deforms the first torque spring 84h so as to increase the winding diameter of the first torque spring 84h.

[0135] In other words, in order for the retard roller 84 to rotate in the forward direction N, a torque in the forward direction N must be applied to the rubber roller 84e and the housing 84f, which elastically deforms the first torque spring 84h so as to increase the winding diameter of the first torque spring 84h. Initially, a torque in the reverse direction -N, which is opposite to the forward direction N, is generated in the retard roller 84 as a braking force.

[0136] In contrast, when the housing 84f and the rubber roller 84e attempt to rotate in the reverse direction -N around the axis C2 relative to the swing arm member 84a, one end of the first torque spring 84h attempts to rotate in the reverse direction -N together with the housing 84f.

[0137] Here, if the inner ring 84g were to not rotate, one end of the first torque spring 84h would rotate in the reverse direction -N together with the housing 84f, and the first torque spring 84h wound around the first portion 84g1 would not rotate, so it would be necessary to elastically deform the first torque spring 84h so as to reduce the winding diameter of the first torque spring 84h.

[0138] When the winding diameter of the first torque spring 84h is reduced, the first torque spring 84h is wound tightly around the outer circumferential surface of the first portion 84g1, and the first portion 84g1 becomes one with the first torque spring 84h. The first torque spring 84h rotates together with the housing 84f because one end of the first torque spring 84h is fixed to the housing 84f, and therefore the inner ring 84g also rotates in the reverse direction -N together with the first torque spring 84h.

[0139] When the inner wheel 84g rotates, the second torque spring 84i wound around the second portion 84g2 rotates integrally with the second portion 84g2 in the reverse direction -N. However, since one end of the second torque spring 84i is fixed to the oscillating arm member 84a, in order for the inner wheel 84g to rotate in the reverse direction -N, a torque is required to elastically deform the second torque spring 84i so as to increase the winding diameter of the second torque spring 84i.

[0140] In other words, in order for the retard roller 84 to rotate in the reverse direction -N, a torque in the forward direction N must be applied to the rubber roller 84e and the housing 84f, which elastically deforms the second torque spring 84i so as to increase the winding diameter of the second torque spring 84i. Initially, the retard roller 84 generates a torque in the forward direction N, which is opposite to the reverse direction -N, as a braking force.

[0141] Here, since the wire diameter of the first torque spring 84h is thicker than the wire diameter of the second torque spring 84i, the retard roller 84 is set so that the torque required to increase the winding diameter of the first torque spring 84h, which has a thick wire diameter (initial torque for the forward direction N) is set to be greater than the torque required to increase the winding diameter of the second torque spring 84i, which has a thinner wire diameter (initial torque for the reverse direction -N), and the initial torque for the reverse direction -N is set to be smaller than the initial torque for the forward direction N.

[0142] (Reverse rotation effect) In the printer 100 equipped with the retard roller 84 configured in this manner, the feed roller 82 is rotated in the reverse direction before the trailing end in the forward direction Q of the top sheet S sent to the delivery path P1 leaves the feed roller 82 due to the action of the retard roller 84 to eliminate double feeding in the forward direction Q. At this time, the leading ends of the top sheet S and the second sheet S in the forward direction Q are misaligned. Then, a propulsive force is applied to the top surface of the top sheet S in contact with the feed roller 82 in the reverse direction -Q due to friction with the feed roller 82.

[0143] When the top sheet of paper S moves in the reverse direction -Q, the second sheet of paper S also tries to move in the reverse direction -Q, using the frictional force with the top sheet of paper S as a driving force. However, since the bottom surface of the second sheet of paper S is in contact with the retard roller 84 and an initial torque is applied to the retard roller 84 in the opposite direction to the rotational direction, a braking force in the opposite direction to the driving force in the reverse direction -Q acts on the bottom surface of the second sheet of paper S.

[0144] Here, the retard roller 84 is set so that the initial torque in the reverse direction -N is smaller than the initial torque in the forward direction N, and this initial torque in the reverse direction -N is set smaller than the frictional force received from the topmost sheet S fed in the reverse direction -Q. As a result, when the second sheet S tries to move in the reverse direction -Q due to the frictional force with the topmost sheet S, the retard roller 84 rotates in the reverse direction -N following the movement of the second sheet S.

[0145] In this manner, the top sheet S and the second sheet S sandwiched between the feed roller 82 and the retard roller 84 move in the reverse direction −Q.

[0146] Since the leading ends of the top sheet S and the second sheet S are misaligned in the forward direction Q, when the second sheet S moves in the reverse direction -Q, it separates from the feed roller 82 and the retard roller 84 before the top sheet S, and the second sheet S falls into the paper tray 20 due to gravity, separating from the top sheet S.

[0147] Then, after the second sheet S has fallen onto the sheet tray 20, and with the top sheet S sandwiched between the feed roller 82 and the retard roller 84, the control unit 90 rotates the feed roller 82 again in the forward direction, and sends the top sheet S to the delivery path P1 in the forward direction Q with the double feeding eliminated.

[0148] In this way, the printer 100 of this embodiment is set so that the magnitude of the reverse torque that suppresses rotation when the retard roller 84 rotates in the forward direction N to feed the paper S in the forward direction Q is different from the magnitude of the reverse torque that suppresses rotation when the retard roller 84 rotates in the reverse direction -N to feed the paper S in the reverse direction -Q. Specifically, the retard roller 84 is set so that the reverse torque that suppresses rotation when the retard roller 84 rotates in the reverse direction -N to feed the paper S in the reverse direction -Q is smaller than the reverse torque that suppresses rotation when the retard roller 84 rotates in the forward direction N to feed the paper S in the forward direction Q.

[0149] As a result, the retard roller 84 stops feeding the second sheet S of the overlapping paper S when rotating in the forward direction N, and allows the second sheet S of the overlapping paper S to be fed in the reverse direction -N, thereby reliably eliminating the overlapping of the sheets S.

[0150] Therefore, the printer 100 of this embodiment can reliably prevent continuous paper feeding and double feeding.

[0151] (Paper tray ramp) Here, the inclined plate 27 of the paper tray 20 is specifically configured as follows: As described above, the printer 100 rotates the feed roller 82 in the reverse direction -N, thereby causing the topmost sheet S and the second sheet S sandwiched between the feed roller 82 and the retard roller 84 to move backward in a direction returning them to the paper tray 20.

[0152] Then, when the second sheet S leaves the feed roller 82 and the retard roller 84, it falls into the paper tray 20 due to its own weight, but the second sheet S is no longer supplied with a backward propulsive force the moment it leaves the feed roller 82 and the retard roller 84. Therefore, the second sheet S loses the backward propulsive force the moment it leaves the feed roller 82 and the retard roller 84.

[0153] Here, as shown in Figures 2 and 4A, the retard roller 84 is positioned so that a portion of it protrudes from the opening 27d formed in the inclined plate 27 of the paper tray 20, so that immediately after the rear end of the retreating second sheet of paper S leaves the retard roller 84, the rear end of the second sheet of paper S rests on the inclined plate 27 shown in Figure 4B.

[0154] The inclined plate 27 is formed with a slope that is higher at the front side than at the rear side in the front-rear direction L and slopes downward toward the rear. Therefore, the second sheet S, which has lost its thrust to move backward, also moves along the inclined surface of the inclined plate 27 by its own weight, as its rear end is placed on the inclined plate 27, the rear side of which is lower than the front side. This allows the printer 100 to move the second sheet S backward and drop it into the paper tray 20 even in a state in which no thrust to move backward is being applied from the feed roller 82 and the retard roller 84.

[0155] Here, if the second sheet S stops at a position immediately after it leaves the feed roller 82 and the retard roller 84 and does not fall into the paper tray 20, the rear end of the second sheet S will be in a state of proximity to the feed roller 82 and the retard roller 84. Then, when the feed roller 82 is rotated again in the forward direction N to re-send the topmost sheet S in the forward direction Q, the rear end of the second sheet S, which remains in a position close to the feed roller 82 and the retard roller 84, will be pulled in the forward direction Q by slight contact with the topmost sheet S that has started to move in the forward direction Q, and double feeding or continuous feeding may occur again, but the printer 100 of this embodiment can avoid such a situation.

[0156] The degree of the gradient (inclination) of the inclined plate 27 with respect to the horizontal direction may be set to such an extent that the second sheet S slides down from the inclined plate 27 under its own weight when the rear end of the second sheet S is placed on the portion immediately after it leaves the feed roller 82 and the retard roller 84. As an example, the degree of such gradient is preferably 25 degrees or more, and more preferably 35 degrees or more.

[0157] In the printer 100 of this embodiment, the control unit 90 may control the hopper 21a to repeatedly move up and down in order to reliably prevent the paper S from getting caught on the inclined plate 27. In this case, even if the paper S gets caught on the inclined plate 27, the control unit 90 moves the hopper 21a up and down, so that the vibration of the hopper 21a caused by the up and down movement is transmitted to the paper S, and the paper S gets released from the inclined plate 27, and the paper S can be reliably returned to the paper tray 20.

[0158] (Paper Guide) Figure 9 is an oblique view showing the positional relationship between paper tray 20 and paper guide 89, Figure 10 is a plan view showing the positional relationship between paper tray 20 and paper guide 89, Figure 11A is a cross-sectional view showing a vertical cross-section along line AA in Figure 10, Figure 11B is a cross-sectional view showing a vertical cross-section along line BB in Figure 10, Figure 11C is a cross-sectional view showing a vertical cross-section along line CC in Figure 10, and Figure 11D is a cross-sectional view showing a vertical cross-section along line DD in Figure 10.

[0159] As shown in FIG. 1, the printer 100 of this embodiment includes paper guides 89 that separate the outer sides of the delivery path P1 and the paper feed path P2, which are part of the arc-shaped cross section of each of the transport paths P1 and P2.

[0160] 9, the paper guide 89 is disposed in the front upper portion of the paper tray 20 when the paper tray 20 is attached to the printer 100. The paper S sandwiched between the feed roller 82 and the retard roller 84 and sent to the pay-out path P1 is sent to the pay-out path P1 with its lower surface in contact with the inclined plate 27 in the forward direction Q from the portion sandwiched between the feed roller 82 and the retard roller 84.

[0161] 9, the lower edge 89b of the paper guide 89 is located forward and above the upper edge 27f of the inclined plate 27. Therefore, a gap is formed between the upper edge 27f of the inclined plate 27 and the lower edge 89b of the paper guide 89, as shown in FIGS.

[0162] Here, if the paper S is stiff, the front end of the paper S in the forward direction Q that has passed through the upper edge 27f while being sandwiched between the feed roller 82 and the retard roller 84 from the paper tray 20 and in contact with the inclined plate 27 is likely to get caught in the gap between the upper edge 27f of the inclined plate 27 and the lower edge 89b of the paper guide 89.

[0163] 2 and 9, in the printer 100 of this embodiment, a part of the inclined plate 27 of the paper tray 20 in the width direction W is hollowed out forward and downward from the surface of the inclined plate 27 to form a recess 27c. The recess 27c is formed on both sides in the width direction W immediately adjacent to the retard roller 84 provided in the center of the width direction W.

[0164] On the other hand, in the printer 100 of this embodiment, the lower edge 89b of the paper guide 89 is not linear along the width direction W, and the portions of the lower end of the paper guide 89 that correspond to the two recesses 27c formed in the inclined plate 27 of the paper tray 20 are formed as protruding pieces 89a that protrude downward from the lower edge 89b, as shown in Figures 9 and 11B. The two protruding pieces 89a are each inserted into the recesses 27c.

[0165] Here, when the protruding piece 89a enters the recessed portion 27c, the surface of the protruding piece 89a is located lower than the portions 27a of the inclined plate 27 arranged on both sides of the retard roller 84 as shown in Fig. 11B, and the portions 27b on the outer side of the recessed portion 27c in the width direction W as shown in Fig. 11C. The lower end edge of the protruding piece 89a extends to the extension range of the inclined plate 27 in the front-rear direction L.

[0166] As a result, in the printer 100 of this embodiment, the leading end of the paper S, which is sandwiched between the feed roller 82 and the retard roller 84 from the paper tray 20 and sent in the forward direction Q, begins to pass above the protruding piece 89a of the paper guide 89 while contacting the inclined plate 27.

[0167] Then, when the front end of the paper S has passed the upper edge 27f of the inclined plate 27, a portion of the front end of the paper S has already been guided by the surface of the protruding piece 89a into the paper guide 89, so that when the front end of the paper S passes above the gap between the upper edge 27f of the inclined plate 27 and the lower edge 89b of the paper guide 89, the paper S does not get into the gap between the upper edge 27f and the lower edge 89b.

[0168] Therefore, the printer 100 of this embodiment can prevent the paper S from getting into the gap between the upper edge 27f of the paper tray 20 and the lower edge 89b of the paper guide 89, regardless of the stiffness of the paper S.

[0169] In addition, the recess 27c of the paper tray 20 and the protruding piece 89a of the paper guide 89 described above are formed at a position close to the center in the width direction W, which is immediately adjacent to the retard roller 84 that contacts the paper S and feeds the paper S, so that the effect of preventing the paper S from getting into the above-mentioned gap can be improved compared to when the recess 27c and the protruding piece 89a are formed at a position close to both sides in the width direction W.

[0170] In addition, the inclined plate 27 of the paper tray 20 has a recessed surface 27e near both sides in the width direction W, which becomes continuously deeper toward the front and downward relative to the surface of portion 27b of the inclined plate 27 as it approaches both side edges, as shown in Figures 2, 9, and 11D.

[0171] In addition, similar to the recessed surfaces 27e of the inclined plate 27 of the paper tray 20, the rear end of the paper guide 89 is formed with recessed surfaces 89c in the areas near both sides in the width direction W, which become continuously deeper toward the front and downward as they approach both side edges, as shown in Figures 9 and 11D.

[0172] Here, the center of the width direction W of the paper S sandwiched between the feed roller 82 and the retard roller 84 and sent in the forward direction Q is supported by the feed roller 82 and the retard roller 84, so that both sides of the unsupported front end of the paper S in the width direction W tend to warp in the thickness direction, and both sides in the width direction W tend to droop lower than the center. Therefore, when the front end of the paper S passes the upper edge 27f of the inclined plate 27, the support of the inclined plate 27 is lost, and the sides of the front end of the paper S tend to droop and get into the gap between the upper edge 27f of the inclined plate 27 and the lower edge 89b of the paper guide 89 more easily than the center.

[0173] However, in the printer 100 of this embodiment, as shown in Figures 9 and 11D, recessed surfaces 27e, 89c are formed in the portion of the inclined plate 27 and the portion of the paper guide 89 through which the hanging both sides of the paper S pass, making it more difficult for the hanging sides of the front end of the paper S to get caught in the gap between the upper edge 27f of the inclined plate 27 and the lower edge 89b of the paper guide 89 compared to the central portion.

[0174] The printer 100 of this embodiment is an example of a dye-sublimation thermal printer, but the printer according to the present invention is not limited to dye-sublimation thermal printers, and other types of printers, such as inkjet printers and thermal printers, can also be used.

[0175] The first aspect of the present invention is A feed roller fixed to the body of the printer; a paper tray that is detachably attached to the main body of the printer and that stores a large number of sheets of paper; a retard rotor that contacts the feed roller when the paper tray is attached to the printer body and sandwiches and conveys the paper stored in the paper tray between the feed roller and the retard rotor; The retard roller is a printer having a base member fixed to the lower front part of the paper tray, a roller member in contact with the feed roller, and a swinging arm member which rotatably supports the roller member at its upper end and is arranged so that its lower end can rotate back and forth relative to the base member, is arranged in an extended position in the height direction, and the roller member is pressed by the feed roller to swing forward.

[0176] The second aspect of the present invention is A feed roller fixed to the body of the printer; a paper tray that is detachably attached to the main body of the printer and that stores a large number of sheets of paper; a retard rotor that contacts the feed roller when the paper tray is attached to the printer body and sandwiches and conveys the paper stored in the paper tray between the feed roller and the retard rotor; In this printer, the roller member of the retard roller that contacts the feed roller is set so that the torque in the reverse direction when feeding the paper in the reverse direction is smaller than the torque in the reverse direction when feeding the paper in the forward direction.

[0177] The third aspect of the present invention is A feed roller fixed to the body of the printer; a paper tray that is detachably attached to the main body of the printer and that stores a large number of sheets of paper; a retard rotor that contacts the feed roller when the paper tray is attached to the printer body and sandwiches and conveys the paper stored in the paper tray between the feed roller and the retard rotor; The retard roller is in contact with the feed roller through an opening formed in an inclined plate having a downward inclination at the front of the paper tray.

[0178] The fourth aspect of the present invention is A feed roller fixed to the body of the printer; a paper tray that is detachably attached to the main body of the printer and that stores a large number of sheets of paper; a retard rotor that contacts the feed roller when the paper tray is attached to the printer body and sandwiches and conveys the paper stored in the paper tray between the feed roller and the retard rotor; a paper guide provided in the printer body and disposed above and in front of the paper tray when the paper tray is attached to the printer body; a portion of the inclined plate of the paper tray in the width direction is hollowed out forward and downward from the surface of the inclined plate to form a recess; a portion of a lower end of the paper guide that corresponds to the recess formed in the inclined plate is formed as a protruding piece that protrudes downward from a lower edge of the paper guide, The printer is in a state where the protruding piece is inserted into the recess. [Explanation of symbols]

[0179] 20 Paper Tray 81 Pickup roller 82 Feed roller 84 Retard roller 84a, 84a' Swing arm member 84b Roller member 84c coil spring 84d Base member 100 Dye-sublimation thermal printer (printer) S Sheet (paper) H Height direction L Anteroposterior direction W Width direction

Claims

1. A feed roller fixed to the body of the printer; a paper tray that is detachably attached to the main body of the printer and that stores a large number of sheets of paper; 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, The retard roller has a base member fixed to the bottom front part of the paper tray, a roller member that contacts the feed roller, and a swinging arm member that rotatably supports the roller member at its upper end and has a lower end that is rotatable back and forth relative to the base member, is arranged in an extended position in the height direction, and swings forward when the roller member comes into contact with the feed roller.

2. 2. The printer according to claim 1, further comprising a coil spring that presses the swing arm member rearward within the rotatable range, and that presses the roller member forward from the feed roller, thereby allowing the roller member to swing forward within the rotatable range.

3. 3. The printer according to claim 1, wherein the roller member is set so that a torque in the reverse direction when feeding the paper in the reverse direction is smaller than a torque in the reverse direction when feeding the paper in the forward direction.

4. 3. The printer according to claim 1, wherein the retard roller is in contact with the feed roller through an opening formed in an inclined plate having a rearwardly downward inclination at the front of the paper tray.

5. a paper guide provided in the printer body and disposed above and in front of the paper tray when the paper tray is attached to the printer body; a portion of the inclined plate of the paper tray in the width direction is hollowed out forward and downward from the surface of the inclined plate to form a recess; a portion of a lower end of the paper guide that corresponds to the recess formed in the inclined plate is formed as a protruding piece that protrudes downward from a lower edge of the paper guide, The printer according to claim 1 or 2, wherein the protruding piece is in a state of being inserted into the recess.

6. The inclined plate of the paper tray is formed with a recessed surface that is continuously deeper toward the front and downward with respect to the surface of the inclined plate in the ranges near both sides in the width direction W as it approaches the both side edges, The printer according to claim 5, wherein the rear end of the paper guide, like the recessed surface of the inclined plate, is formed as a recessed surface in the area near both sides in the width direction W, the recessed surface becoming continuously deeper toward the front and downward as it approaches the both side edges.

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