printer

Abstract

In order to prevent a feed direction of a paper from significantly varying due to swinging of a retard roller within an allowable range of an insertion depth of a paper tray relative to main body of a printer, a printer (100) a pickup roller (81) and a feed roller (82) fixed to a main body, a paper tray that is detachably attached, and a retard roller (84) that contacts the feed roller (82) and carries the housed paper (S) by sandwiching with the feed roller (82) when the paper tray (20) is attached, wherein the retard roller (84) includes a base member (84d) fixed to a lower portion of a front portion of the paper tray (20), a roller member (84b) that contacts the feed roller (82), and a swinging arm member (84a) that rotatably supports the roller member (84b) at an upper end portion, has a lower end portion provided to be rotatable forward and backward relative to the base member (84d), is disposed to extend in a height direction (H), and swings forward by the roller member (84b) pressed by the feed roller (82).

Description

[TECHNICAL FIELD]

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

[0002] A printer includes a drawer paper tray relative to a main body. The paper tray houses stacked multiple sheets cut to a predetermined size (hereinafter referred to as "paper"). The main body of the printer includes a pickup roller and a feed roller. These rollers rotate in contact with the uppermost paper among the multiple sheets housed in the paper tray, thereby feeding that paper into a paper feed path.

[0003] When feeding paper using the pickup roller and the feed roller, the second paper stacked directly below the uppermost sheet (sheet positioned directly below uppermost sheet) may sometimes be fed together with the uppermost sheet in a stacked state due to static electricity or other factors, causing multiple feed. If multiple feed occurs, it may cause paper jam in a subsequent paper path or result in misalignment of the print in a print portion.

[0004] Therefore, to eliminate the multiple feed, a retard roller is positioned to contact the feed roller in opposition, and the paper is fed by being sandwiched between the feed roller and the retard roller. In this case, the uppermost sheet contacting the feed roller receives the torque from the feed roller, causing the uppermost sheet to be fed. Since the retard roller receives the torque in the direction opposite to the feed direction of the feed roller, the second paper that advanced overlapping the uppermost sheet is stopped by the torque of the retard roller, separated from the uppermost sheet, and the multiple feed is solved (see, e.g., Patent Literature 1).[Prior Art Documents][Patent Literature]

[0005] [Patent Literature 1] Japanese Patent Publication No. 6035312B[Summary of Invention][Problem to be solved]

[0006] Here, it is necessary to set the contact pressure between the feed roller and the retard roller within a predetermined fixed range. However, in a printer where the feed roller is provided in the main body of the printer and the retard roller is provided in the paper tray, the contact pressure between the feed roller and the retard roller varies depending on the insertion depth of the paper tray relative to the main body. Therefore, it is desirable that the insertion depth of the paper tray relative to the main body be constant.

[0007] However, the printer operates normally even if the insertion depth of the paper tray relative to the main body varies slightly due to manufacturing tolerances or handling of a printer. That is, even if the insertion depth relative to the main body is small, the printer operates normally as long as that small depth remains within a certain range, similar to the specified insertion depth.

[0008] Therefore, the retard roller is configured so that the contact pressure does not vary significantly even if the position where it contacts the feed roller changes, causing the angle of oscillation to vary. Furthermore, it is required that the orientation of the common tangent line at the contact position between the feed roller and the retard roller does not significantly change due to the oscillation of the retard roller within the allowable range of the insertion depth of the paper tray relative to the main body (range within which printer operates normally).

[0009] The present invention has been made in light of the above circumstances and aims to provide a printer where the direction of the common tangent line between the feed roller and the retard roller does not significantly vary due to the oscillation of the retard roller within the allowable range of the insertion depth of the paper tray relative to the main body.[Solution to Problem]

[0010] The present disclosure provides a printer including a feed roller fixed to a main body of the printer, a paper tray that is detachably attached to the main body of the printer and houses many sheets, and a retard roller that contacts the feed roller and carries the paper housed in the paper tray by sandwiching the paper with the feed roller when the paper tray is attached to the main body of the printer, wherein the retard roller includes a base member fixed to a lower portion of a front portion of the paper tray, a roller member that contacts the feed roller, and a swinging arm member that rotatably supports the roller member at an upper end portion, has a lower end portion provided to be rotatable forward and backward relative to the base member, is disposed to extend in a height direction, and swings forward when the roller member contacts the feed roller.[Effects of Invention]

[0011] The printer of the present disclosure prevents significant variation in the orientation of the common tangent line between the feed roller and the retard roller by the swing of the retard roller within the allowable range of the insertion depth of the paper tray relative to the main body.[Brief Description of Drawings]

[0012] [FIG. 1] FIG. 1 is a cross section view with a vertical plane passing through a center of a width direction W of a dye-sublimation thermal printer (hereinafter referred to as printer) and extending in a front and back direction L. [FIG. 2] FIG. 2 is a perspective view illustrating a paper tray. [FIG. 3] FIG. 3 is a schematic diagram illustrating a simplified FIG. 1. [FIG. 4A] FIG. 4A is a partial cross section view (Part 1) corresponding to FIG. 1, illustrating a structure and an operation of a pickup roller, a feed roller, and a retard roller. [FIG. 4B] FIG. 4B is a partial cross section view (Part 2) corresponding to FIG. 1, illustrating a structure and an operation of the pickup roller, the feed roller, and the retard roller. [FIG. 5] FIG. 5 is a perspective view illustrating the retard roller. [FIG. 6] FIG. 6 is a cross section view illustrating the inside of the retard roller. [FIG. 7A] FIG. 7A is a perspective view (Part 1) describing a configuration for generating a torque difference in the retard roller. [FIG. 7B] FIG. 7B is a perspective view (Part 2) describing a configuration for generating a torque difference in the retard roller. [FIG. 8A] FIG. 8A is a cross section view corresponding to FIG. 4A, illustrating a structure and an operation of a comparative example where a roller member of a retard roller swings vertically about an axis of a front end portion of a swinging arm member as a rotation fulcrum with the swinging arm member extending rearward in the front and back direction from a position forward of the roller member. [FIG. 8B] FIG. 8B is a cross section view corresponding to FIG. 4B, illustrating a structure and an operation of a comparative example where the roller member of the retard roller swings vertically about the axis of the front end portion of the swinging arm member as a rotation fulcrum with the swinging arm member extending rearward in the front and back direction from a position forward of the roller member. [FIG. 9] FIG. 9 is a perspective view illustrating the relative positions of the paper tray and a paper guide. [FIG. 10] FIG. 10 is a plan view illustrating the relative positions of the paper tray and the paper guide. [FIG. 11A] FIG. 11A is a cross section view illustrating a cross section along a line A-A in FIG. 10. [FIG. 11B] FIG. 11B is a cross section view illustrating a cross section along a line B-B in FIG. 10. [FIG. 11C] FIG. 11C is a cross section view illustrating a cross section with a vertical plane along a line C-C in FIG. 10. [FIG.11D] FIG. 11D is a cross section view illustrating a cross section with a vertical plane along a line D-D in FIG. 10. [Detailed Description of Embodiments]

[0013] An embodiments of a printer according to the present invention is described below with reference to the drawings.

[0014] [Overall Configuration of Printer] FIG. 1 is a cross section view of a sublimation thermal printer 100 (hereinafter referred to as printer 100) with a vertical plane passing through a center of a width direction W and extending in a front and back direction L.

[0015] The illustrated printer 100 is one embodiment of the printer according to the present invention. The printer 100 houses both of a sheet S (hereinafter simply referred to as paper S) that is precut to a predetermined size and a roll paper R (hereinafter simply referred to as paper R) that is formed by winding a single long sheet into a roll, and can selectively pint and output onto either of the paper S or the paper R.

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

[0017] <Case> The case 10 is an outer cover including inside thereof the print portion 30, the cutter portion 40, the creasing portion 50, the roll paper storage portion 60, the transport portion 70, the control portion 90, and the transport path P. The case 10, the print portion 30, the cutter portion 40, the creasing portion 50, the roll paper storage portion 60, the transport portion 70, the control portion 90, and the transport path P constitute a main body of the printer 100. As described later, the paper tray 20 is detachable from the main body of the printer 100. A discharge port 15 for discharging the printed paper S, R is formed in a front panel covering the front surface of the case 10 in a longitudinal direction L.

[0018] <Paper Tray> FIG. 2 is a perspective view illustrating the paper tray 20. The paper tray 20 houses many papers S (sheet S) stacked in the thickness direction. The paper tray 20 is detachably attached to the main body of the printer 100 in a drawer type manner. Specifically, the paper tray 20 is positioned at the lowermost portion of the printer 100. As illustrated by a white filled arrow in FIG. 1, the paper tray 20 can be removed from the main body of the printer 100 by pulling it forward in the front and back direction L. The paper tray 20 that is removed from the main body of the printer 100 is attached to the main body of the printer 100 as illustrated in FIG. 1. The detailed structure of the paper tray 20 is described later.

[0019] <Roll Paper Storage Portion> The roll paper storage portion 60 is provided above the paper tray 20, toward the front in the front and back direction L. The roll paper storage portion 60 is a portion that stores the roll paper R. As illustrated in FIG. 1, the roll paper storage portion 60 stores the roll paper R with its axis parallel to the width direction W of the printer 100 and with the paper wound counterclockwise from the center toward the periphery. The roll paper R stored in the roll paper storage portion 60 is pulled out from the lower end of the roll paper R in the right direction of FIG. 1 and unwound, thereby rotating counterclockwise as illustrated.

[0020] <Print Portion> The print portion 30 is positioned behind the roll paper storage portion 60 in the front and back direction L. The print portion 30 prints onto the paper S, R passing through the portion of the transport path P (described later as print path P3) that rises substantially vertically behind the roll paper storage portion 60 by the control of the control portion 90.

[0021] The print portion 30 includes a thermal head 31, an ink ribbon 32, and a platen roller 33. The ribbon of the ink ribbon 32 is coated with sublimation dye. The ink ribbon 32 feeds the ribbon from a feed roll 32a to a take-up roll 32b in synchronization with the transport of the paper S, R. Heat generated by the thermal head 31 in contact with the ink ribbon 32 causes the sublimation dye in the ink ribbon 32 to diffuse and transfer onto the paper S, R, thereby performing printing.

[0022] The platen roller 33 is positioned opposite to the ink ribbon 32 and the thermal head 31, sandwiching the paper S, R being carried through the print path P3 described later. The platen roller 33 presses the paper S, R against the ink ribbon 32.

[0023] <Cutter Portion> The cutter portion 40 is positioned in front of the roll paper storage portion 60. The cutter portion 40 operates under the control from the control portion 90. The cutter portion 40 cuts the paper R passing through the portion of the transport path P extending forward from above the roll paper storage portion 60 (described later as discharge path P9) along the width direction W. As described above, the cutter portion 40 cuts the roll paper R into a predetermined length. However, the cutter portion can also cut off unnecessary edges, etc., from the paper S as a sheet.

[0024] <Creasing Portion> The creasing portion 50 is positioned behind the roll paper storage portion 60 in the front and back direction L and between the print portion 30 and the paper tray 20 in the height direction H. The creasing portion 50 operates under the control from the control portion 90. The creasing portion 50 forms a crease, which is a groove extending in the width direction W, on the paper S passing through the portion of the transport path P extending along the front and back direction L below the roll paper storage portion 60 (described later as creasing path P7). Note that while the creasing portion 50 forms creases on the paper S as described above, it may also form creases on the roll paper R by controlling the cutting and the transport.

[0025] <Transport Path > FIG. 3 is a schematic diagram illustrating a simplified FIG. 1 to clearly illustrate the transport path P. The transport path P is a passage through which the papers S, R are transported by a transport portion 70, illustrated in FIG. 3 by a dotted line. The reference numeral Q illustrated beside the transport path P indicates the forward direction for feeding the paper S from the paper tray 20 toward the discharge port 15 and the forward direction for feeding the paper R from the roll paper storage portion 60 toward the discharge port 15. The reference numeral -Q indicates the reverse direction that is opposite to the forward direction Q.

[0026] The transport path P includes a sheet feed path P1, a sheet supply path P2, a print path P3, a standby path P4, a post print path P5, a reverse standby path P6, a creasing path P7, a roll paper supply path P8, and a discharge path P9.

[0027] The sheet feed path P1 (hereinafter simply referred to as feed path P1) is a transport path where the paper S stored in the paper tray 20 is fed out one sheet at a time. The feed path P1 extends diagonally upward and forward from the front end of the paper tray 20. A device for feeding the paper S from the paper tray 20 to the feed path P1 is the pickup roller 81 and the feed roller 82 provided on the main body of the printer 100. However, to prevent the multiple feed of the paper S, the retard roller 84 provided on the paper tray 20 is also used.

[0028] When feeding the paper S, a hopper 21a of the paper tray 20 is raised. The operation of the feeding of the paper S is described late together with the structure of the retard roller 84.

[0029] The sheet supply path P2 (hereinafter simply referred to as supply path P2) is a transport path following the discharge path P1. The sheet supply path P2 extends upward from the front end of the discharge path P1, then turns back to extend rearward and downward within the space formed in front of the roll paper storage portion 60. The sheet supply path P2 extends rearward through the space between the roll paper storage portion 60 and the paper tray 20, and is further provided up to a position rising upward behind the roll paper storage portion 60.

[0030] The print path P3 follows the supply path P2, extending upward from the front end of the supply path P2 along the rear of the roll paper storage portion 60, and further extending forward to the front portion above the roll paper storage portion 60. The platen roller 33 and the thermal head 31 of the aforementioned print portion 30 are arranged facing each other across the print path P3.

[0031] The standby path P4 follows the print path P3, extending from the front end of the print path P3 to the front upper part of the roll paper storage portion 60. The standby path P4 then extends downward in a concentric circle with the outer circumference of the roll paper storage portion 60, in front of the roll paper storage portion 60, to a position just before the standby path P4 meets the supply path P2.

[0032] The print downstream path P5 follows the print path P3, extending diagonally downward and forward behind the roll paper storage portion 60 from the rear end of the print path P3 to pass outside the paper supply path P2.

[0033] The reverse standby path P6 follows the print downstream path P5, extending from the front end of the print downstream path P5, traversing the space between the paper feed path P2 and the paper tray 20 in the forward direction L. The front end of the reverse standby path P6 connects to the rear end of the sheet supply path P2. The paper S passing through the reverse standby path P6 has its face (illustrated facing down) already printed. When transported again through the sheet supply path P2 from the reverse standby path P6, the face of the paper S (facing up) in the reverse standby path P6 becomes the target for printing by the print portion 30 when it subsequently passes through the print path P3. Therefore, the reverse standby path P6 and the sheet supply path P2 together form a reversal path that reverses the front and back sides of the paper S.

[0034] The creasing path P7 follows the reverse standby path P6, extending from the rear end of the reverse standby path P6 above the paper tray 20 toward the rear in the front and back direction L. The creasing portion 50 is positioned within the creasing path P7.

[0035] The roll paper supply path P8 extends rearward from the approximate bottom of the roll paper storage portion 60, rises upward at the rear of the roll paper storage portion 60, and is provided up to the rear end of the print path P3.

[0036] The discharge path P9 follows the print path P3, extending from the front end of the print path P3 over the top of the roll paper storage portion 60 toward the front in the front and back direction L to the discharge port 15. The cutter portion 40 is provided in the discharge path P9.

[0037] <Transport Portion> The transport portion 70 is provided in the transport path P. The transport portion 70 operates under the control of the control portion 90. The transport portion 70 transports the papers S, R along the transport path P and also switches the transport path P to be fed. The transport portion 70 is mainly composed of a drive roller driven by a motor (not shown) controlled by the control portion 90, a non-drive roller lacking driving force, and switching members 71, 72, 73 that switch the transport path P.

[0038] The roller pair of the transport portion 70, consisting of a normal drive roller and a driven roller that transport the papers S, R by gripping them, is omitted from the illustration and description. The transport portion 70 includes the pickup roller 81, the feed roller 82, and the retard roller 84 described later. These pickup roller 81, the feed roller 82, and the retard roller 84 are described later.

[0039] The switching member 71 is provided at the front end of print path P3. The switching member 71 switches whether the papers S, R, which have been fed in the forward direction Q through the print path P3, are sent to the standby path P4 to be printed on, or are sent to the discharge path P9 to be discharged. The switching of the transport path by the switching member 71 is performed under the control of the control portion 90.

[0040] The switching member 72 is provided at the rear end of the print path P3. The switching member 72 operates as a switching valve that returns the paper S sent in the reverse direction -Q from the print path P3 to the print downstream path P5, preventing it from mistakenly entering the roll paper supply path P8. The switching member 72 is biased with a spring toward the side blocking the roll paper supply path P8.

[0041] Thus, when the printed paper is the paper S of a sheet of paper, the switching member 72 directs the paper S sent in the reverse direction -Q through the print path P3 to the print downstream path P5.

[0042] On the other hand, when the printed paper is a roll paper R, the switching member 72 is biased with a spring toward the side blocking the roll paper supply path P8. However, as the paper R is a continuous body, even if the leading end of the paper R has reached the print path P3, the portion connected to the rolled paper R housed in the roll paper storage portion 60 pushes the switching member 72 open against the spring force, creating a path to the roll paper supply path P8. Therefore, when the paper R sent in the reverse direction -Q through the print path P3 is to be rewound into the roll paper supply path P8, the switching member 72 can smoothly rewind the paper R into the roll paper supply path P8 without obstruction.

[0043] The switching member 73 is provided at the rear end of the print downstream path P5. The switching member 73 operates as a switching valve to reliably send the paper S, which has been transported in the reverse direction -Q after being sent to the reverse standby path P6, to the creasing path P7 without returning it to the print downstream path P5.

[0044] The switching member 73 is biased by a spring toward the side that sends the paper S to the creasing path P7. The printed paper S is positioned with its trailing edge in the reverse standby path P6. However, during printing, the trailing edge of the paper S remains in the print downstream path P5. That is, during printing, the paper S is not sent with its trailing edge into the reverse standby path P6, and its trailing edge remains in the print downstream path P5.

[0045] Subsequently, for printing the second color and subsequent colors, the paper S is transported in the reverse direction -Q through the print downstream path P5 and returned again to the standby path P4. The printer 100 then repeats the aforementioned print operation to perform multicolor printing and coating.

[0046] Thus, during multicolor printing, the paper S is positioned to extend over the reverse standby path P6 and the print downstream path P5. In this state, the paper S presses against the switching member 73 against the force of the spring, causing the switching member 73 to shift to the position that feeds the paper S into the print downstream path P5.

[0047] <Control Portion> The control portion 90 is positioned above the paper tray 20, behind the print portion 30. The control portion 90 controls the operation of the print portion 30, the cutter portion 40, the creasing portion 50, and the transport portion 70.

[0048] [Overview of Operation of Printer] <For Paper S (Sheet of Paper S)> For the paper S passing through the aforementioned transport path P, the printer 100 operates as follows. First, the paper S housed in the paper tray 20 is fed out in the forward direction Q along the feed path P1. It is then fed in the forward direction Q along the supply path P2, is fed in the forward direction Q along print path P3, and is subsequently fed in the forward direction Q along the standby path P4.

[0049] The paper S is then fed through the standby path P4 in the reverse direction -Q. While being fed through the print path P3 in the reverse direction -Q, the printing is performed on one side (side facing thermal head 31) at the print portion 30. When performing the multicolor printing on the paper S in the print portion 30, or when performing the coating after the printing, the paper S is repeatedly fed in both the forward direction Q and the reverse direction -Q through the print path P3 and the standby path P4.

[0050] The paper S printed in the print portion 30 is then fed in the forward direction Q (equivalent to reverse direction -Q in print path P3) through the print downstream path P5, then in the forward direction Q through the reverse standby path P6, then in the forward direction Q through the supply path P2, and then in the forward direction Q through the print path P3. As described above, the paper S turns over by passing through the reverse standby path P6 and the supply path P2.

[0051] If the printer 100 completes the printing only one side of the paper S, the paper S is then fed in the forward direction Q through the discharge path P9 and is discharged from the printer 100 to the outside via the discharge port 15 to complete the process.

[0052] If the printer 100 prints on both sides of the paper S, the paper S, after being fed in the forward direction Q through the print path P3, is fed in the forward direction Q through the standby path P4.

[0053] The paper S is then fed in reverse direction -Q through the standby path P4. Subsequently, while being fed in reverse direction -Q through the print path P3, the printing is performed on the other side (side facing thermal head 31) in the print portion 30. When performing the multicolor printing on the paper S in the print portion 30, or when performing the coating after the printing, the paper S is repeatedly fed in the forward direction Q and the reverse direction -Q through the print path P3 and the standby path P4.

[0054] The printed paper S from the print portion 30 is then fed in the forward direction Q through the print downstream path P5, then is fed in the forward direction Q through the reverse standby path P6, then is fed in the forward direction Q through the supply path P2, then is fed in the forward direction Q through the print path P3, then is fed in the forward direction Q through the discharge path P9, and finally is discharged from the printer 100 through the discharge port 15 to complete the process.

[0055] When creasing the printed paper S, for single-sided printing, if the paper S after single-sided printing is in the reverse standby path P6, it is fed through the reverse standby path P6 in the reverse direction -Q, then is fed through the creasing path P7 in the reverse direction -Q, and is creased in the creasing portion 50.

[0056] When creasing the printed paper S, for both side printing, after the both side printing, if the paper S is in the reverse standby path P6, it is fed in the reverse direction -Q through the reverse standby path P6, then is fed in the reverse direction -Q through the creasing path P7, and creased in the creasing portion 50.

[0057] <For Paper R (Roll Paper R)> For the paper R passing through the aforementioned transport path P, the printer 100 operates as follows. First, the paper R stored in the roll paper storage portion 60 is unwound from the roll by being fed in the forward direction Q along the roll paper supply path P8.

[0058] The paper R is then fed in the forward direction Q through the print path P3, followed by being fed in the forward direction Q through the standby path P4.

[0059] The paper R is then returned in the reverse direction -Q through the standby path P4, followed by being returned in the reverse direction -Q through the print path P3. During this return, the printing is performed on one side (side facing thermal head 31) in the print portion 30. When the paper R is returned in the reverse direction -Q, it is rewound onto the roll.

[0060] When performing the multicolor printing on the paper R in the print portion 30, or when coating after the printing, the paper is repeatedly fed in the forward direction Q and the reverse direction -Q through the print path P3 and the standby path P4.

[0061] The printed paper R from the print portion 30 is then fed in the forward direction Q through the print path P3. It is subsequently fed in the forward direction Q through the discharge path P9 and cut to a predetermined length in the cutter portion 40. The printed paper R that separated from the roll by cutting is discharged from the printer 100 through the discharge port 15 to complete the process.

[0062] The paper R, with the printed portion cut off and the connected portion remaining on the roll, is rewound onto the roll in the roll paper storage portion 60. This returns the paper R to the reverse direction -Q along the discharge path P9, the print path P3, and the roll paper supply path P8.

[0063] [Retard Roller and Paper Tray] FIGS. 4A, 4B are partial cross section views corresponding to FIG. 1, illustrating the structure and the operation of the pickup roller 81, the feed roller 82, and the retard roller 84. FIG. 5 is a perspective view illustrating the retard roller 84. FIG. 6 is a cross section view illustrating the interior of the retard roller 84, and FIGS. 7A, 7B are exploded perspective views illustrating the configuration that generates the torque difference in the retard roller.

[0064] FIG. 4A illustrates the paper tray 20 mounted in the normal position (reference position) in the front and back direction L relative to the main body of the printer 100. FIG. 4B illustrates the paper tray 20 mounted in a position forward of the reference position (position forward in front and back direction L relative to reference position).

[0065] FIG. 7A illustrates a view looking up from the outer lower side in the width direction W of the retard roller 84, and FIG. 7B illustrates a view looking down from the inner upper side in the width direction W of the retard roller 84.

[0066] The pickup roller 81 and the feed roller 82 are fixed to the main body of the printer 100 via the arm 83. The pickup roller 81 and the feed roller 82 are positioned above the paper tray 20 and at a location corresponding to the upper and front portion of the paper tray 20, specifically near where the front plate 22 of the paper tray 20 is formed in the front and back direction L, when the paper tray 20 is attached to the main body of the printer 100.

[0067] The pickup roller 81 and the feed roller 82 are integrally formed by the arm 83. The arm 83 positions the pickup roller 81 rearward of the feed roller 82 in the front and back direction L. Furthermore, the arm 83 is positioned in an overall inclined posture such that the pickup roller 81 is located below the feed roller 82 in the height direction H. However, the arm 83 is rotatable coaxially with the rotational axis of the feed roller 82 and is biased by a spring to press the pickup roller 81 against the paper S housed in the paper tray 20.

[0068] The pickup roller 81 and the feed roller 82 are driven by a single motor. Therefore, the pickup roller 81 and the feed roller 82 rotate and stop synchronously, and when rotating, they rotate in the same direction relative to each other.

[0069] <Details of the Paper Tray> As illustrated in FIG 2, the paper tray 20 is formed into a thin box like (tray) structure with no top plate. The paper tray 20 includes a bottom plate 21 where the paper S is stacked, side plates 24, 25 rising on both sides in the width direction W in the thickness direction of the paper S (height direction H of printer 100), a rear plate 23 rising at the rear in the front and back direction L, and a front plate 22 rising at the front in the front and back direction L.

[0070] The front portion 21a of the bottom plate 21 is formed to freely swing upward about the axis C3 at its rear end. That is, the front portion 21a operates as a hopper that lifts the front portion of the paper S placed on the bottom plate 21 upward while tilted upward. Hereinafter, this front portion 21a is referred to as a hopper 21a. The hopper 21a is moved vertically by a motor (not illustrated) installed in the main body of the printer 100. The motor that moves the hopper 21a vertically is driven under the control of the control portion 90.

[0071] The paper tray 20 has an inclined plate 27 extending diagonally upward and forward from the upper edge of the front plate 22. That is, the inclined plate 27 has a rearward slope. An opening 27d is formed at the central portion in the width direction W of the inclined plate 27. The inclined plate 27 is described in more detail later.

[0072] The paper tray 20 has a front cover member 26 connected to the portions of the side plates 24, 25 extending forward of the front plate 22 and to the inclined plate 27. The front cover member 26 is formed extending in the width direction W forward of the front plate 22. The front cover member 26 is formed extending outward in the width direction W beyond the respective side plates 24, 25.

[0073] The paper tray 20 pulled forward in the front and back direction L from the main body of the printer 100 is mounted onto the main body of the printer 100 as illustrated in FIG. 1. This is achieved by pushing the front cover member 26 rearward (in opposite direction of white filled arrow in FIG. 1) into a space formed at the lowest part of the printer 100, extending in the front and back direction L. 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 and back direction L.

[0074] The paper tray 20 includes a retard roller 84 illustrated in FIG. 2. The retard roller 84 is positioned in the space formed at the front of the paper tray 20 between the front plate 22 and the front cover member 26. A portion of the retard roller 84 protrudes above the surface of the inclined plate 27 through the opening 27d formed in the inclined plate 27.

[0075] During the feeding operation of the paper S from the paper tray 20, the hopper 21a of the paper tray 20 is lifted upward by the plate 19 (see FIGS. 1, 4A, 4B) provided in the main body of the printer 100 and is operated under the control of the control portion 90. This plate 19 pushes up the hopper 21a through the opening 20A (see FIG. 1) formed in the bottom surface of the paper tray 20, thereby tilting the hopper 21a. (see FIGS. 1, 4A, 4B) installed in the main body of the printer 100 and is operated under the control of the control portion 90. This plate 19 pushes up the hopper 21a through the opening 20A (see FIG. 1) formed in the bottom surface of the paper tray 20, lifting it upward into an inclined position (indicated by two-dot chain line in FIG. 2).

[0076] Regardless of the number of the papers S housed in the paper tray 20 is configured to incline upward such that the uppermost paper S among the papers S lifted by the hopper 21a, as illustrated in FIGS. 4A, 4B, contacts the pickup roller 81, lifting it, and the extension line of the leading end of that paper S contacts the rear end of the inclined plate 27 without contacting the feed roller 82.

[0077] The retard roller 84 provided in the paper tray 20 faces the interior of the paper tray 20 from the opening 27d of the inclined plate 27 of the paper tray 20, as illustrated in FIG. 2. Furthermore, as illustrated in FIG. 4A, when the paper tray 20 is installed in the normal position of the main body of the printer 100, the retard roller 84 is arranged to contact the feed roller 82 fixed to the main body of the printer 100.

[0078] <Retard Roller> (Configuration) The retard roller 84 is a driven roller and is not driven itself. However, by driving the feed roller 82 and sandwiching the paper S between the driven feed roller 82 and the non-driven retard roller 84, the paper S is fed to the feed path P1.

[0079] The retard roller 84, as illustrated in detail in FIG. 5, includes a base member 84d, two swinging arm members 84a, a roller member 84b, and two coil springs 84c.

[0080] The base member 84d is positioned in the front space between the front plate 22 and the front cover member 26, as illustrated in FIG. 4A, and is fixed to the bottom of the paper tray 20. The base member 84d has a vertical wall 84k extending upward in the height direction H from its front portion.

[0081] The roller member 84b is a substantially cylindrical roller that contacts the feed roller 82. Although the detailed structure of the roller member 84b will be described later, when rotating about the axis C2, the roller member 84b generates a reverse torque (torque opposite to rotational direction) to apply braking to the rotation.

[0082] The swinging arm member 84a is an elongated plate-like member supporting the roller member 84b on the base member 84d. The swinging arm member 84a is positioned with its longitudinal direction aligned along the height direction H of the printer 100. The swinging arm member 84a is positioned perpendicular to the axis C2 at both ends of the roller member 84b, which is arranged with its axis C2 oriented along the width direction W of the printer 100.

[0083] The swinging arm member 84a supports the roller member 84b for rotation about the axis C2 at its upper end portion (upper end) in the longitudinal direction. At its lower end portion (lower end) in the longitudinal direction, it is supported by the base member 84d for rotation about the axis C1 parallel to the axis C2. Thus, the swinging arm member 84a is supported relative to the base member 84d so that it can swing back and forth about the axis C1, as indicated by the black arrow in FIG. 5, causing the roller member 84b to swing back and forth.

[0084] The coil spring 84c is arranged along the front and back direction L between the swinging arm member 84a and the vertical wall 84k, with one end contacting the swinging arm member 84a and the other end contacting the vertical wall 84k. Consequently, the coil spring 84c pushes the swinging arm member 84a rearward within its range of the swinging motion.

[0085] Therefore, when there are no obstacles that control the position on roller member 84b, the retard roller 84 is biased by the elastic force of the coil spring 84c and remains positioned rearward within the swinging range. On the other hand, when the roller member 84b contacts a forwardly positioned member or the like, the retard roller 84 swings, compressing the coil spring 84c, and displaces forwardly within its swingable range.

[0086] (Basic Operation for Eliminating Multi Feed by Retard Roller) The retard roller 84 configured as described above operates together with the feed roller 82 as follows.

[0087] The paper tray 20 that holds the paper S is mounted on the main body of the printer 100 at a reference position in the front and back direction L, as illustrated in FIG. 4A. At this time, the feed roller 82 fixed to the main body of the printer 100 abuts the upper rear portion of the roller member 84b of the retard roller 84 on the paper tray 20, pressing the roller member 84b downward and forward.

[0088] Consequently, the swinging arm member 84a that supports the roller member 84b is pushed toward the front within its swinging range. The coil spring 84c elastically deforms under the pushed load, so that the swinging arm member 84a is displaced toward the front within its swinging range.

[0089] Then, under the control of the control portion 90, the hopper 21a is lifted, and one uppermost paper S (hereinafter referred to as uppermost paper S) of the stacked papers S is pressed against the pickup roller 81.

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

[0091] When the pickup roller 81 rotates forward, the uppermost paper S pressed against the pickup roller 81 is fed in the forward direction Q due to the forward rotation torque of the pickup roller 81. When the uppermost paper S is fed in the forward direction Q, its leading end contacts the rear end of the inclined plate 27. However, since the leading end of the paper S is inclined upward, the paper S bends such that its leading end bends toward the upper side of the inclined plate 27. The leading end of the paper S then contacts the retard roller 84 that rotates in the same direction as the feed roller 82, and is further sandwiched between the feed roller 82 and the retard roller 84.

[0092] Here, if the second paper S is multiple fed on the uppermost paper S, the leading end of the uppermost paper S deflects upward upon contacting the rear end of the inclined plate 27. However, the second paper S is less likely to deflect simultaneously with the uppermost paper S, thereby making it difficult for the second paper S to reach the retard roller 84.

[0093] When the uppermost paper S is sandwiched between the feed roller 82 and the retard roller 84, the uppermost paper S is fed onto the feed path P1 at a feed angle θ1 that is the direction of the common tangent line M between the feed roller 82 and the retard roller 84 relative to the horizontal direction. Then, after the uppermost paper S is fed a certain distance along the feed path P1, the hopper 21a is lowered to its original position under the control of the control portion 90. The pick up roller 81 thereby separates from the uppermost paper S.

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

[0095] First, when only one paper S is fed out by the pickup roller 81, i.e., when only the uppermost paper S is fed out, only that uppermost paper S is sandwiched between the feed roller 82 and the retard roller 84. Since the feed roller 82 rotates in the forward direction, the top surface of the uppermost paper S experiences a propulsive power in the forward direction Q due to the friction with the feed roller 82.

[0096] Meanwhile, the bottom surface of the uppermost paper S contacts the retard roller 84. When the uppermost paper S moves in the forward direction Q, it attempts to rotate the retard roller 84 in the forward rotation direction N. However, as described above, an initial torque in the opposite direction to the rotation direction (forward rotation direction N) is applied to the retard roller 84. Therefore, a braking force in the opposite direction to the propulsive force in the forward direction Q operates on the bottom surface of the uppermost paper S.

[0097] Here, the initial torque applied to 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. Consequently, the uppermost paper S is fed along the feed path P1 in the forward direction Q by the propulsive power of the feed roller 82, despite the braking force received from the retard roller 84.

[0098] Next, it will be described the case where the paper S fed by the pickup roller 81 is multiple fed, specifically, this occurs when the second paper S that contact the uppermost paper S is attracted to the uppermost paper S due to static electricity or similar forces and is fed out together with the uppermost paper S.

[0099] When the multiple feed occurs, the uppermost paper S and the second paper S are sandwiched between the feed roller 82 and the retard roller 84 in an overlapping state. The top surface of the uppermost paper S that contacts the feed roller 82 experiences the propulsive power in the forward direction Q due to the friction with the feed roller 82 caused by being sandwiched between the retard roller 84 and the feed roller 82.

[0100] When the uppermost paper S moves in the forward direction Q, the second paper S attempts to move in the forward direction Q using the frictional force with the uppermost paper S as the propulsive force. However, as the bottom surface of the second paper S contacts the retard roller 84, and an initial torque opposite to the rotational direction is applied to the retard roller 84, a braking force acting in the opposite direction to the propulsive force in the forward direction Q from the retard roller 84 acts on the bottom surface of the second paper S.

[0101] Here, the propulsive force in the forward direction Q acting on the second paper S is the frictional force with the uppermost paper S. This frictional force is considerably smaller than the propulsive force from the torque of the feed roller 82 acting on the uppermost paper S and does not exceed the braking force received from the retard roller 84. As a result, the uppermost paper S is fed in the forward direction Q along the feed path P1; however, the second paper S is held while being sandwiched between the feed roller 82 and the retard roller 84 to be stopped.

[0102] This allows the uppermost paper S to be separated from the second paper S and fed into the feed path P1.

[0103] (Operation by Swinging Arm Member) In the printer 100 of this embodiment, since the roller member 84b of the retard roller 84 swings about the axis C1 at the lower end of the swinging arm member 84a extending in the height direction H. This reduces variation in the feeding direction of the paper S corresponding to the misalignment of the mounting position of the paper tray 20 in the front and back direction L, compared to a configuration where the roller member 84b of the retard roller 84 swings vertically about a pivot point at the front end of the swinging arm member extending in the front and back direction L from a position ahead of the roller member 84b.

[0104] Specifically, the paper tray 20 is inserted in the front and back direction L relative to the main body of the printer 100 and is mounted at a reference position. However, the printer 100 is configured to operate normally even if the insertion depth of the paper tray 20 relative to the main body of the printer 100 varies slightly due to the manufacturing tolerances of the printer 100 or for convenience of handling the printer 100.

[0105] The printer 100 requires the contact pressure between the feed roller 82 and the retard roller 84 to be within a predetermined fixed range to properly feed the paper S to solve the multiple feed. Therefore, to prevent significant variation in the contact pressure between the feed roller 82 and the roller member 84b of the retard roller 84, regardless of the insertion depth of the paper tray 20 relative to the main body of the printer 100, when the roller member 84b of the retard roller 84 contacts the feed roller 82, the swinging arm member 84a swings, changing the position of the roller member 84b. This absorbs the fluctuation in the contact pressure between the feed roller 82 and the roller member 84b of the retard roller 84.

[0106] Here, when the paper tray 20 is positioned in the forward direction L relative to the reference position (FIG. 4A) of the main body of the printer 100 (i.e., position forward in forward direction L relative to reference position, see FIG. 4B), the portion of the roller member 84b contacting the feed roller 82 is positioned higher and more forward than in the reference position.

[0107] Consequently, the displacement amount of the swinging arm member 84a swinging forward becomes smaller than that in the reference position. The feed 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 feed angle θ1 of the common tangent line M in the reference position. The common tangent line M sandwiched between the feed roller 82 and the roller member 84b of the retard roller 84 determines the orientation (feed direction) of the paper S fed onto the feed path P1.

[0108] An experiment showed that the feed angle θ1 was, for example, 49.49 [degrees] and the feed angle θ2 was, for example, 50.12 [degrees]. That is, the variation Δθ in the feed direction of the paper S corresponding to the deviation of the mounting position of the paper tray 20 in the front and back direction L is, for example, 0.63 (=50.12 - 49.49) [degrees].

[0109] FIGS. 8A, 8B illustrate a structure and an operation of a comparative example. In this example, the roller member 84b of the retard roller 84 swings vertically by a swinging arm member 84a' extending rearward in the front and back direction L from a position forward of the roller member 84b. The swinging arm member 84a' swings about the axis C4 at its front end. FIG. 8A illustrates a state corresponding to FIG. 4A where the paper tray 20 is positioned at the standard position (reference position) of a main body of a printer 100'. FIG. 8B illustrates a state corresponding to FIG. 4B where the paper tray 20 is positioned at a location forward of the reference position (position forward in front and back direction L relative to reference position).

[0110] As shown in FIGS. 8A, 8B, the roller member 84b of the retard roller 84 is supported at its rear end by the swinging arm member 84a' extending forward of the roller member 84b in the front and back direction. The swinging arm member 84a' swings vertically about its front end axis C4.

[0111] In the comparative example, as illustrated in FIG. 8A, when the paper tray 20 is inserted into the reference position of the main body of the printer 100', the upper rear portion of the retard roller 84 abuts the feed roller 82. Consequently, the swinging arm member 84a' of the retard roller 84 displaces downwardly within its swinging range about the axis C4. In this state, the feed angle of the common tangent line M between the feed roller 82 and the retard roller 84 is θ1'.

[0112] On the other hand, in the comparative example as illustrated in FIG. 8B, when the paper tray 20 is positioned in the front position in the front and back direction L (position in front and back direction L relative to reference position) relative to the reference position of the main body of the printer 100 (FIG. 8A), the portion of the retard roller 84 contacting the feed roller 82 is positioned more forward and upward than in the reference position. Note that the state of the paper tray 20 positioned in the comparison example, where it is placed in the position forward in the front and back direction L relative to the reference position of the main body of the printer 100 is set under the same state as the state illustrated in FIG. 4B for the printer 100 of the present embodiment.

[0113] In this case, the feed angle θ2' of the common tangent line M between the feed roller 82 and the retard roller 84 becomes larger than the feed angle θ1' of the common tangent line M between the feed roller 82 and the retard roller 84 at the reference position. The experiment showed that the feed angle θ1' was, for example, 51.83 [degrees], and the feed angle θ2' was, for example, 59.87 [degrees]. That is, the variation Δθ' in the feed direction of the paper S corresponding to the deviation of the mounting position of the paper tray 20' in the front and back direction L is, as one example, 8.04 (= 59.87 - 51.83) [degrees].

[0114] Thus, in the printer 100 of the present embodiment, the retard roller 84 has a structure where the roller member 84b swings back and forth by the swinging arm member 84a extending in the height direction H, compared to the comparative example where the retard roller 84 has a structure where the roller member 84b swings up and down by the swinging arm member 84a' extending in the front and back direction L to swing the roller member 84b vertically. This allows the printer 100 of the present embodiment to reduce the variation Δθ in the paper feed direction corresponding to the deviation of the mounting position of the paper tray 20'in the front and back direction L, compared to the comparative example having a structure where the roller member 84b swings vertically by the swinging arm member 84a extending in the front and back direction L.

[0115] Consequently, the printer 100 of this embodiment, due to the small variation Δθ in the feed direction of the paper S regardless of the deviation of the mounting position of the paper tray 20' in the front and back direction L, suppresses the paper S fed into the feed path P1 from catching on the surrounding wall (especially inner wall) that partitions the feed path P1, thereby suppressing the risk of the paper S jamming in the feed path P1.

[0116] Furthermore, while the swinging arm member 84a of the printer 100 of the present embodiment is longer than the swinging arm member 84a' of the comparative example, this is one factor that reduces the variation Δθ in the paper feed direction compared to the comparative example. However, the primary factor reducing the variation Δθ in the feed direction is the structure that allows the swinging arm member 84a to swing back and forth.

[0117] Furthermore, the printer 100 of the present embodiment reduces the variation Δθ in the feed direction of the paper S corresponding to the deviation of the mounting position of the paper tray 20 in the front and back direction L by orienting the swinging arm member 84a in a posture aligned with the height direction H. However, the operation of reducing the variation Δθ in the feed direction of the paper S is not limited to the roller member 84b supported by the swinging arm member 84a operating as the retard roller 84.

[0118] That is, the printer with the swinging arm member 84a oriented along the height direction H can reduce the variation Δθ in the feed direction of the paper S corresponding to the deviation of the mounting position of the paper tray 20' in the front and back direction L, even if the roller member 84b supported by the swinging arm member 84a is merely a follower roller that does not apply an initial torque (braking) in the opposite direction to its rotation. Therefore, the printer with the swinging arm member 84a oriented along the height direction H may have the roller member 84b supported by the swinging arm member 84a as a simple driven roller.

[0119] (Detailed Structure and Operation During Reverse Rotation of Retard Roller) The basic function of the retard roller 84 to solve the multiple feed is as described above. However, if the feed roller 82 continues to rotate forward even after the leading end of the uppermost paper S in the forward direction Q has moved away from the feed roller 82, the torque of the feed roller 82 acts on the second paper S that is stopped in contact with the retard roller 84, causing the second paper S to be fed into the feed path P1. In this case, the second paper S is fed in a continuous feeding state with almost no gap between the second paper S and the uppermost paper S already fed into the feed path P1.

[0120] To avoid such continuous feed, after the leading end of the uppermost paper S is fed into the supply path P2 following the feed path P1, the control portion 90 drives a separate drive roller (not illustrated one of transport portion 70) installed in the supply path P2 to feed the uppermost paper S in the forward direction Q while stopping the feed roller 82, thereby preventing continuous feed of the second paper S.

[0121] However, if the printer 100 is configured to drive both the separate drive roller installed in the sheet supply path P2 and the feed roller 82 with a single motor, it is not possible to drive only the separate drive roller installed in the sheet supply path P2 while stopping the feed roller 82.

[0122] Therefore, in this printer 100, the control portion 90 reverses the feed roller 82 before the leading end of the uppermost paper S in the forward direction Q moves away from the feed roller 82. That is, at this time, the uppermost paper S and the second paper S are in a state where the positions of their leading ends in the forward direction Q are misaligned.

[0123] Therefore, by reversing the feed roller 82, the uppermost paper S and the second paper S overlapping it are retracted together toward the paper tray 20. This allows the second paper S whose leading end is positioned further back relative to the forward direction Q to separate from the position sandwiched between the feed roller 82 and the retard roller 84 before the uppermost paper S. Consequently, only the second paper S can be returned to the paper tray 20.

[0124] However, if the retard roller 84 merely generates the torque in the opposite direction to the rotation direction (reverse torque), the retard roller 84 only feeds the uppermost paper S in the reverse direction -Q, and stops the second paper S, so that the retard roller 84 can not return only the second paper S to the paper tray 20 as intended.

[0125] Therefore, the printer 100 of the present embodiment configures the retard roller 84 to generate a different reverse torque during the rotation in the forward direction and during the rotation in the reverse direction. The detailed structure of the retard roller 84 that generates the different reverse torque is described below.

[0126] (Detailed Configuration) The roller member 84b as illustrated in FIGS. 6, 7A, 7B has a structure comprising 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 formed with the same winding direction relative to 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 integrally. The inner ring 84g has an axial end portion 84g1 (hereinafter referred to as first portion 84g1) positioned inside the housing 84f, while the other axial end portion 84g2 (hereinafter referred to as second portion 84g2) protrudes outward from the of the housing 84f in the width direction W and is positioned inside the swinging arm member 84a. The inner ring 84g is freely rotatable relative to both the housing 84f and the swinging arm member 84a.

[0128] The first torque spring 84h is arranged to be wound around the outer peripheral surface of the first portion 84g1 of the inner ring 84g. One end of the first torque spring 84h extends radially outward and is fixed to the inner peripheral surface of the housing 84f. The second torque spring 84i is arranged to be wound around the outer peripheral surface of the second portion 84g2 of the inner ring 84g. One end of the second torque spring 84i extends radially outward and is fixed to the inner peripheral surface of the swinging arm member 84a.

[0129] The first torque spring 84h and the second torque spring 84i have coils wound in the same direction relative to each other. 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 when the roller member 84b rotates about the axis C2 relative to the swinging arm member 84a is described. When the housing 84f and the rubber roller 84e rotate in the forward direction N around the axis C2 relative to the swinging arm member 84a, the end 84h1 of the first torque spring 84h is fitted into the groove 84f1 of the housing 84f, so that the end 84h1 of the first torque spring 84h rotates integrally with the housing 84f in the forward rotation direction N.

[0131] Here, since the first torque spring 84h is wound around the first portion 84g1 of the inner ring 84g, for the first end 84h1 of the first torque spring 84h to rotate in the forward rotation direction N, either the first torque spring 84h rotates integrally with the inner ring 84g in the forward rotation direction N, or only the first end 84h1 of the first torque spring 84h rotates in the forward rotation direction N. When the inner ring does not rotate and only one end 84h1 of the first torque spring 84h rotates in the forward rotation direction N, this results in elastic deformation of the first torque spring 84h in the direction that increases the winding diameter. 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 impeded.

[0132] If the inner ring 84g rotates integrally with the first torque spring 84h in the forward rotation direction N, the second portion 84g2 that is a part of the inner ring 84g also rotates in the forward rotation direction N. Since the second torque spring 84i is wound around the second portion 84g2, the second torque spring 84i also rotates in the forward rotation direction N. However, one end 84i1 of the second torque spring 84i is fixed by being fitted into the groove 84a1 formed on the inner circumferential surface of the swinging arm member 84a. Therefore, the one end 84i1 of the second torque spring 84i does not rotate. In this case, it is necessary for the second torque spring 84i to elastically deform in a direction that reduces the winding diameter.

[0133] However, reducing the winding diameter of the second torque spring 84i increases the tightness with which the second torque spring 84i wraps around the outer surface of the second portion 84g2, preventing the second portion 84g2 from slipping relative to the second torque spring 84i. Consequently, the inner ring 84g does not rotate in the forward direction N and maintains its stopped state.

[0134] As described above, one end of the first torque spring 84h rotates integrally with the housing 84f in the forward rotation direction N. However, the first portion 84g1 around which the first torque spring 84h is wound does not rotate. For the housing 84f to rotate in the forward rotation direction N, a torque that elastically deforms the first torque spring 84h is required to increase the winding diameter of the first torque spring 84h.

[0135] In other words, for the retard roller 84 to rotate in the forward direction N, it is necessary for a torque in the forward direction N that elastically deform the first torque spring 84h to be applied to the rubber roller 84e and the housing 84f to increase the winding diameter. Consequently, a torque in the reverse direction -N opposite to the forward direction N initially acts as a braking force on the retard roller 84.

[0136] On the other hand, when the housing 84f and the rubber roller 84e rotates in the reverse direction -N about the axis C2 relative to the swinging arm member 84a, one end of the first torque spring 84h rotates in the reverse direction -N integrally with the housing 84f.

[0137] Here, when the inner ring 84g does not rotate, one end of the first torque spring 84h rotates integrally with the housing 84f in the reverse direction -N. Since the first torque spring 84h wrapped around the first portion 84g1 does not rotate, it is necessary for the first torque spring 84h to elastically deform the first torque spring 84h to reduce the winding diameter.

[0138] Reducing the winding diameter of the first torque spring 84h increases the tightening force with which the first torque spring 84h wraps around the outer circumferential surface of the first portion 84g1, causing the first portion 84g1 to become integral with the first torque spring 84h. Since one end of the first torque spring 84h is fixed to the housing 84f, it rotates with the housing 84f. Consequently, the inner ring 84g also rotates integrally with the first torque spring 84h in the reverse direction -N.

[0139] When the inner ring 84g rotates, the second torque spring 84i wrapped around the second part 84g2 rotates integrally with the second part 84g2 in the reverse direction -N. Since one end of the second torque spring 84i is fixed to the swinging arm member 84a, a torque that elastically deforms the second torque spring 84i is required to increase the winding diameter, for the inner ring 84g to rotate in the reverse direction -N.

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

[0141] Here, since the wire diameter of the first torque spring 84h is thicker than that of the second torque spring 84i, the torque (initial torque in the forward direction N) required to increase the winding diameter of the first torque spring 84 having a thick wire diameter is set larger than the torque (initial torque in the reverse direction -N) required to increase the winding diameter of the second torque spring 84i having a thin wire diameter. Consequently, the initial torque in the reverse direction -N is set smaller than the initial torque in the forward direction N.

[0142] (Operation during Reverse Rotation) A printer 100 equipped with the retard roller 84 configured in this manner reverses the feed roller 82 before the rear edge of the uppermost paper S, which has been fed into the feed path P1, moves away from the feed roller 82 due to the operation of the retard roller 84 that solves the multiple feed in the forward direction Q. At this time, the leading ends of the uppermost paper S and the second paper S are misaligned in the forward direction Q. Furthermore, the top surface of the uppermost paper S, which is in contact with the feed roller 82, experiences a propulsive force in the reverse direction -Q due to friction with the feed roller 82.

[0143] When the uppermost paper S moves in the reverse direction -Q, the second paper S also attempts to move in the reverse direction -Q with the friction force with the uppermost paper S as a propulsive force. However, the bottom surface of the second paper S contacts the retard roller 84. Since an initial torque in the opposite direction of the rotation is applied to the retard roller 84, a braking force in the opposite direction of the propulsive force towards the reverse direction -Q acts on the bottom surface of the second paper S.

[0144] Here, the retard roller 84 is set such that the initial torque for the reverse direction -N is smaller than the initial torque for the forward direction N. This initial torque for the reverse direction -N is set smaller than the frictional force received from the uppermost paper S being sent in the reverse direction -Q. As a result, when the second paper S attempts to move in the reverse direction -Q due to the frictional force with the uppermost paper S, the retard roller 84 rotates in the reverse direction -N in response to the movement of the second paper S.

[0145] In this manner, the uppermost paper S and the second paper 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 uppermost paper S and the second paper S are misaligned in the forward direction Q, the movement in the reverse direction -Q causes the second paper S to separate from the feed roller 82 and the retard roller 84 before the uppermost paper S. The second paper S then falls by gravity into the paper tray 20, and separates from the uppermost paper S.

[0147] Then, after the second paper S has fallen into the paper tray 20 and while the uppermost paper S is held between the feed roller 82 and the retard roller 84, the control portion 90 rotates the feed roller 82 forward again. When the multiple feed is solved, the uppermost paper S is fed in the forward direction Q into the feed path P1.

[0148] In this way, the printer 100 of this embodiment is configured such that the magnitude of the reverse torque that suppresses the rotation of the retard roller 84 differs depending on whether it rotates in the forward rotation direction N that feeds the paper S in the forward direction Q or in the reverse rotation direction -N that feeds the paper S in the reverse direction -Q. Specifically, the retard roller 84 is set such that the reverse torque suppressing rotation when rotating in the reverse direction -N to feed the paper S in the reverse direction -Q is smaller than the reverse torque suppressing rotation when rotating in the forward direction N to feed the paper S in the forward direction Q.

[0149] This allows the retard roller 84, during the rotation in the forward direction N, to stop feeding the second paper S that has been multiple fed, and to allow the feeding of the second paper S in the reverse direction -N, thereby reliably solving the multiple feeding of the paper S.

[0150] Therefore, the printer 100 of this embodiment can reliably prevent the continuous feed and the multiple feed.

[0151] (Paper Tray Inclined Plate) Here, the inclined plate 27 of the paper tray 20 is configured in detail as follows. As described above, the printer 100 reverses the feed roller 82 in the reverse direction -N, causing the uppermost paper S and the second paper S sandwiched between the feed roller 82 and the retard roller 84 to retreat in the direction of returning to the paper tray 20.

[0152] Then, when the second paper S separates from the feed roller 82 and the retard roller 84, the second paper S falls into the paper tray 20 due to its own weight. However, at the moment in which the second paper S separates from the feed roller 82 and the retard roller 84, the backward propulsive force is stopped being supplied. Therefore, the second paper S loses its backward propulsive force at the moment in which the second paper S separates from the feed roller 82 and the retard roller 84.

[0153] Here, as illustrated in FIGS. 2, 4A, the retard roller 84 is positioned such that a part of the retard roller 84 protrudes from the opening 27d formed in the inclined plate 27 of the paper tray 20. Consequently, immediately after the rear end of the second paper S moving backward separates from the retard roller 84, the rear end of the second paper S is placed on the inclined plate 27 as illustrated in FIG. 4B.

[0154] The inclined plate 27 is formed with a rearward slope, where the front side in the longitudinal direction L is higher than the rear side. Consequently, the second paper S that has lost its backward propulsion force also moves along the inclined surface of the inclined plate 27 due to its own weight, as its trailing edge is placed on the inclined plate 27 that is lower at the rear compared to the front. Thus, even when the printer 100 does no receive a backward propulsive force from the feed roller 82 and the retard roller 84, the printer 100 can retract the second paper S and drop it into the paper tray 20.

[0155] When the second paper S stops immediately after moving away from the feed roller 82 and the retard roller 84 and does not fall into the paper tray 20, the rear end of the second paper S remains in a position close to the feed roller 82 and the retard roller 84. Then, when the feed roller 82 rotates again in the forward direction N to refeed the uppermost paper S in the forward direction Q, the rear end of the second paper S that remains in a position close to the feed roller 82 and the retard roller 84 is pulled in the forward direction Q by slight contact with the uppermost paper S that has started moving in the forward direction Q. This could potentially cause the multiple feed or the continuous feed again. However, the printer 100 of this embodiment can avoid such a situation.

[0156] The degree of inclination (slope) of the inclined plate 27 relative to the horizontal direction needs only be set such that the second paper S slides off the inclined plate 27 under its own weight when its trailing edge is placed on the portion immediately after it has moved away from the feed roller 82 and the retard roller 84. As an example of such a gradient degree, 25 degrees or more is preferred, and 35 degrees or more is more preferred.

[0157] Furthermore, to reliably prevent the paper S from catching on the inclined plate 27, the control portion 90 may control the hopper 21a to repeatedly move up and down. In this case, even if the paper S is caught on the inclined plate 27, the control portion 90 can move the hopper 21a up and down. The vibration of the hopper 21a caused by this up and down movement is transmitted to the paper S, releasing the paper S from being caught on the inclined plate 27 and reliably returning the paper S to the paper tray 20.

[0158] (Paper Guide) FIG. 9 is a perspective view illustrating the relative positions of the paper tray 20 and the paper guide 89. FIG. 10 is a plan view illustrating the relative positions of the paper tray 20 and the paper guide 89. FIG. 11A is a cross section view illustrating a section along an A-A line in FIG. 10 through a vertical plane. FIG. 11B is a cross section view illustrating a section along a vertical plane through a B-B line in FIG. 10. FIG. 11C is a cross section view illustrating a section along a vertical plane through a C-C line in FIG. 10. FIG. 11D is a cross section view illustrating a section along a vertical plane through a D-D line in FIG. 10.

[0159] The printer 100 of this embodiment, as illustrated in FIG. 1, includes a paper guide 89 that partitions the outer sides of each of the transport paths P1, P2 with arc-shaped portions in the cross sections of the feed path P1 and the supply path P2.

[0160] The paper guide 89 is provided on the main body of the printer 100. When the paper tray 20 is mounted on the main body of the printer 100, the paper guide 89 is positioned in front and above the paper tray 20 as illustrated in FIG. 9. The paper S fed into the feed path P1 by being sandwiched between the feed roller 82 and the retard roller 84 is fed into the feed path P1 with its bottom surface contacting the inclined plate 27 in the forward direction Q beyond the portion sandwiched between the feed roller 82 and the retard roller 84.

[0161] The lower edge 89b of the paper guide 89 is positioned forward and upward relative to the upper edge 27f of the inclined plate 27 as illustrated in FIG. 9. Consequently, 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 illustrated in FIGS. 9, 10, 11A, 11C, 11D.

[0162] Here, when the paper S has high stiffness, the leading end of the paper S in the forward direction Q that has passed the upper edge 27f of the inclined plate 27 while being sandwiched between the feed roller 82 and the retard roller 84 after leaving the paper tray 20 easily enters the gap between the upper edge 27f of the inclined plate 27 and the lower edge 89b of the paper guide 89.

[0163] However, in the printer 100 of this embodiment, a portion of the inclined plate 27 of the paper tray 20 in the width direction W is recessed downward and forward relative to the surface of the inclined plate 27 to form a concave portion 27c as illustrated in FIGS. 2, 9. This concave portion 27c is formed on both sides of the width direction W immediately adjacent to the retard roller 84 provided at the central portion 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 straight along the width direction W. Instead, the portions of the lower end of the paper guide 89 corresponding to the two concave portions 27c formed in the inclined plate 27 of the paper tray 20 are formed as a protruding piece 89a extending downward beyond the lower edge 89b as illustrated in FIGS. 9, 11B. These two protruding pieces 89a then enter the concave portions 27c, respectively.

[0165] Here, when the protruding piece 89a enters the concave portion 27c, the surface of the protruding piece 89a is positioned lower than the portion 27a of the inclined plate 27 located on both sides of the retard roller 84 as illustrated in FIG. 11B, and lower than the portion 27b of the concave portion 27c located on the outer side in the width direction W as illustrated in FIG. 11C. Furthermore, the lower edge of the protruding piece 89a extends the extended range of the inclined plate 27 in the front and back direction L.

[0166] Accordingly, in the printer 100 of this embodiment, the leading end of the paper S fed from the paper tray 20 and sandwiched between the feed roller 82 and the retard roller 84 in the forward direction Q passes above the protruding piece 89a of the paper guide 89 while contacting the inclined plate 27.

[0167] Then, with the leading end of the paper S having passed the upper edge 27f of the inclined plate 27, a portion of the leading end of the paper S is already guided by the surface of the protruding piece 89a onto the paper guide 89. Therefore, when the leading 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 enter the gap between the upper edge 27f and the lower edge 89b.

[0168] Accordingly, the printer 100 of this embodiment can prevent the paper S from entering 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] Furthermore, the concave portion 27c of the paper tray 20 and the protruding piece 89a of the paper guide 89 described above are formed in a position close to the central portion in the width direction W, immediately adjacent to the retard roller 84 that contacts and feeds the paper S. This configuration enhances the effectiveness of preventing the paper S from entering the aforementioned gap compared to cases where the concave portion 27c and protruding piece 89a are formed in positions closer to either side in the width direction W.

[0170] Furthermore, the inclined plate 27 of the paper tray 20 is formed with a recessed surface 27e in the range near both sides in the width direction W as illustrated in FIGS. 2, 9, 11D. This surface continuously deepens toward the front and bottom relative to the surface of the portion 27b of the inclined plate 27 as it approaches both side edges.

[0171] Furthermore, the rear end portion of the paper guide 89 is also formed with a recessed surface 89c similar to the recessed surface 27e of the inclined plate 27 of the paper tray 20. As illustrated in FIGS. 9, 11D, the range near both sides of this recessed surface 89c in the width direction W continuously deepens toward the front and bottom as it approaches both side edges.

[0172] Here, the paper S fed in the forward direction Q between the feed roller 82 and the retard roller 84 has its central portion in the width direction W supported by the feed roller 82 and the retard roller 84. Consequently, as the side portions of the unsupported leading end of the paper S in the width direction W bend in the thickness direction, the side portions in the width direction W sags downward more easily than the central portion. Consequently, when the leading end of the paper S passes over the upper edge 27f of the inclined plate 27, the support from the inclined plate 27 is lost. This causes the side portions of the leading end of the paper S to sag, making them more likely to enter 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.

[0173] However, as illustrated in FIGS. 9, 11D, the printer 100 of this embodiment has the recessed surfaces 27e, 89c formed respectively in the portion of the inclined plate 27 through which both drooping sides of the paper S pass and in the portion of the paper guide 89. This makes it difficult for the drooping sides of the leading end of the paper S to enter 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 that applies a sublimation thermal printer. However, the printer according to the present invention is not limited to a sublimation thermal printer and can also apply other types of printers, such as inkjet printers or thermal printers using a heat-sensitive method.

[0175] A first of the present invention is a printer including: a feed roller fixed to a main body of the printer; a paper tray that is detachably attached to the main body of the printer and houses many sheets; and a retard roller that contacts the feed roller and carries the paper housed in the paper tray by sandwiching the paper with the feed roller when the paper tray is attached to the main body of the printer, wherein the retard roller includes a base member fixed to a lower portion of a front portion of the paper tray, a roller member that contacts the feed roller, and a swinging arm member that rotatably supports the roller member at an upper end portion, has a lower end portion provided to be rotatable forward and backward relative to the base member, is disposed to extend in a height direction, and swings forward when the roller member contacts the feed roller.

[0176] A second of the present invention is a printer including: a feed roller fixed to a main body of the printer; a paper tray that is detachably attached to the main body of the printer and houses many sheets; and a retard roller that contacts the feed roller and carries the paper housed in the paper tray by sandwiching the paper with the feed roller when the paper tray is attached to the main body of the printer, wherein the roller member of the retard roller that contacts the feed roller is set such that a reverse torque in a reverse direction when feeding the paper in the reverse direction is smaller than a reverse torque in a forward rotation direction when feeding the paper in a forward direction.

[0177] A third of the present invention is a printer including: a feed roller fixed to a main body of the printer; a paper tray that is detachably attached to the main body of the printer and houses many sheets; and a retard roller that contacts the feed roller and carries the paper housed in the paper tray by sandwiching the paper with the feed roller when the paper tray is attached to the main body of the printer, wherein the retard roller contacts the feed roller through an opening formed in an inclined plate having a backwardly sloping inclination at a front portion of the paper tray.

[0178] A fourth of the present invention is a printer including: a feed roller fixed to a main body of the printer; a paper tray that is detachably attached to the main body of the printer and houses many sheets; a retard roller that contacts the feed roller and carries the paper housed in the paper tray by sandwiching the paper with the feed roller when the paper tray is attached to the main body of the printer; and a paper guide that is provided in the main body of the printer, and is disposed above the front of the paper tray when the paper tray is attached to the main body of the printer, wherein a portion of the inclined plate of the paper tray in a width direction is recessed forward and downward relative to a surface of the inclined plate to form a concave portion, wherein a portion of the lower end portion of the paper guide that corresponds to the concave portion formed in the inclined plate is formed as a protrusion that protrudes downward relative to a lower end edge of the paper guide, and wherein the protrusion enters the concave portion.[Cross-Reference to Related Applications]

[0179] The present application claims priority based on Patent Application No. 2023-105686 filed with the Japan Patent Office on June 28, 2023, and its entire disclosure is hereby incorporated by reference in its entirety.

Claims

1. A printer comprising: a feed roller fixed to a main body of the printer; a paper tray that is detachably attached to the main body of the printer and houses many sheets; and a retard roller that contacts the feed roller and carries the paper housed in the paper tray by sandwiching the paper with the feed roller when the paper tray is attached to the main body of the printer, wherein the retard roller includes a base member fixed to a lower portion of a front portion of the paper tray, a roller member that contacts the feed roller, and a swinging arm member that rotatably supports the roller member at an upper end portion, has a lower end portion provided to be rotatable forward and backward relative to the base member, is disposed to extend in a height direction, and swings forward when the roller member contacts the feed roller.

2. The printer according to claim 1, comprising a coil spring that presses the swinging arm member backward within a rotatable range to be swingable forward within the rotatable range when the roller member is pressed forward by the feed roller.

3. The printer according to claim 1 or 2, wherein the roller member is set such that a reverse torque in a reverse direction when feeding the paper in the reverse direction is smaller than a reverse torque in a forward rotation direction when feeding the paper in a forward direction.

4. The printer according to claim 1 or 2, wherein the retard roller contacts the feed roller through an opening formed in an inclined plate having a backwardly sloping inclination at a front portion of the paper tray.

5. The printer according to claim 1 or 2, comprising a paper guide that is provided in the main body of the printer, and is disposed above the front of the paper tray when the paper tray is attached to the main body of the printer, wherein a portion of the inclined plate of the paper tray in a width direction is recessed forward and downward relative to a surface of the inclined plate to form a concave portion, wherein a portion of the lower end portion of the paper guide that corresponds to the concave portion formed in the inclined plate is formed as a protrusion that protrudes downward relative to a lower end edge of the paper guide, and wherein the protrusion enters the concave portion.

6. The printer according to claim 5, wherein the inclined plate of the paper tray includes a region near both side portions in the width direction W that is formed as a recessed surface that continuously deepens forward and downward relative to a surface of the inclined plate toward both side edges, and wherein a rear end portion of the paper guide includes a region near the both side portions in the width direction W that is formed as a recessed surface, similar to the recessed surface of the inclined plate, that continuously deepens forward and downward toward the both side edge.

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