printer

Abstract

To prevent or suppress the occurrence of double feed and eliminate double feed and also prevent or suppress the occurrence of continuous feeding of paper, a printer (100) includes a pickup roller (81) and a feed roller (82) that are fixed to a body of printer (100) and rotate synchronously; a paper tray (20) that stores a plurality of sheet papers (S) and moves a hopper (21a) up and down, the hopper being a part of bottom plate (21); a retarding roller (84) that contacts the feed roller (82) and transports paper (S) stored in paper tray (20) such that the paper (S) is sandwiched between the retarding roller (84) and the feed roller (82), with the paper tray (20) attached to the body of printer (100); and a control portion (90) that controls operations of the pickup roller (81), the feed roller (82), and the hopper (21a). The control portion (90) performs a double-feed elimination process, a continuous-feed prevention process, and a main feed process.

Description

[Technical Field]

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

[0002] Printers include paper trays that are pulled from the body. The paper tray stores a plurality of stacked sheet papers cut to a predetermined size (hereinafter referred to as "papers"). The printer's body includes a pickup roller and a feed roller that rotate in contact with the topmost paper of a plurality of papers stored in the paper tray, thereby feeding that paper into a paper feed path.

[0003] When the paper is fed by the pickup roller and the feed roller, double feed may occur in which the second paper stacked directly beneath the topmost sheet (paper arranged next to the topmost paper) is fed together with the topmost paper due to static electricity or other factors in a condition that the second paper overlaps the topmost paper. If such double feed occurs, it may cause a paper jam in the paper path downstream or cause misalignment in printing in the printing portion.

[0004] Thus, to eliminate double feed, a retarding roller is provided to face and contact the feed roller and then feed the paper sandwiched between the feed roller and the retarding roller. In this case, the topmost paper in contact with the feed roller is fed by receiving torque from the feed roller. The retarding roller applies torque in the direction opposite to the feed direction of the feed roller, thereby stopping the second paper that has advanced with the topmost paper in an overlapping manner, separating it from the topmost paper, and eliminating double feed.

[0005] Here, when the second paper is kept in contact with the retarding roller, the second paper is brought into contact with the feed roller when the topmost paper has left the feed roller, thereby feeding the second paper. This results in continuous feeding, in which the second paper is fed without a sufficient interval from the topmost paper fed earlier. Since the interval between the papers is insufficient, the continuous feeding makes it difficult to control the preset transport or printing.

[0006] Thus, to avoid the continuous feeding, there have been proposed techniques that ensure a sufficient interval between the topmost paper and the second paper by cutting off the drive force to the feed roller or by reversing the feed roller to send the second paper backward (see, for example, Patent Literatures 1 and 2).[Prior Art Documents][Patent Literature]

[0007] [Patent Literature 1] Japanese Patent Application Publication No. H6-250475 [Patent Literature 2] Japanese Patent No. 4046993 [Summary of Invention][Problem to be solved]

[0008] However, the techniques disclosed in the above patent literatures do not return the second paper to its state prior to the double feed. Thus, when the second paper has stopped immediately after leaving the retarding roller, its transport may start when the front end of the second paper slightly touches the feed roller.

[0009] The present invention is made in view of the situation. Its object is to provide a printer that can prevent or suppress the occurrence of double feed, eliminate double feed by reliably returning the double-fed second paper to its state before the double feed, even when such double feed has occurred, and also prevent or suppress the occurrence of continuous feeding of the paper.[Solution to Problem]

[0010] The present invention provides a printer. The printer includes a pickup roller and a feed roller that are fixed to a body of the printer and are configured to rotate synchronously; a paper tray that is configured to store a plurality of sheet papers and to move a hopper up and down, the hopper being a part of a bottom plate of the paper tray; a retarding roller that is configured to contact the feed roller and to transport sheet paper stored in the paper tray such that the sheet paper is sandwiched between the retarding roller and the feed roller, with the paper tray attached to the body of the printer; and a control portion that is configured to control operations of the pickup roller, the feed roller, and the hopper. The control portion is configured to perform (1) a double-feed elimination process, the double-feed elimination process performed by rotating the pickup roller in a forward rotational direction corresponding to a forward direction of the paper to feed the topmost paper in the forward direction, and feed the topmost paper in the forward direction while being sandwiched between the feed roller and the retarding roller, thereby separating a second paper, fed in an overlapped condition with the topmost paper, from the topmost paper; (2) a continuous-feed prevention process, which is performed after the double-feed elimination process, the continuous-feed prevention process performed by rotating the feed roller in a reverse rotational direction, which is opposite to the forward rotational direction, while the hopper is lowered, thereby separating the second paper from the retarding roller; and (3) a main feed process, which is performed after the continuous-feed prevention process, the main feed process performed by rotating the feed roller in the forward rotational direction, thereby feeding the topmost paper.[Effects of Invention]

[0011] The printer according to the present invention prevents or suppresses the occurrence of double feed, eliminates double feed by reliably returning the double-fed second paper to its state before the double feed, even when such double feed occurs, and also prevents or suppresses the occurrence of continuous feeding of the paper.[Brief Description of Drawings]

[0012] [FIG. 1] FIG. 1 is a cross-sectional view taken by a vertical plane that is along a front-rear direction L and passes the center in the width direction W of a dye-sublimation thermal printer (hereinafter, referred to as "printer"). [FIG. 2] FIG. 2 is a perspective view showing a paper tray. [FIG. 3] FIG. 3 is a view schematically expressing a simplification of FIG. 1. [FIG. 4] FIG. 4 is a partial cross-sectional view corresponding to FIG. 1, for illustrating the structure and function of a pickup roller, a feed roller, and a retarding roller. [FIG. 5A] FIG. 5A is a schematic view (Part 1) illustrating the operation when a paper S stored in the paper tray is delivered to a delivery path P1 under the control of a control portion, showing the initial state. [FIG. 5B] FIG. 5B is a schematic view (Part 2) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a state where a hopper has been raised. [FIG. 5C] FIG. 5C is a schematic view (Part 3) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a separation process. [FIG. 5D] FIG. 5D is a schematic view (Part 4) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a state where the hopper has been lowered after the separation process. [FIG. 5E] FIG. 5E is a schematic view (Part 5) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a backlash adjustment process. [FIG. 5F] FIG. 5F is a schematic view (Part 6) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a process to send the paper in a forward direction after raising the hopper. [FIG. 5G] FIG. 5G is a schematic view (Part 7) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a process to send the paper in the forward direction by the feed roller and the retarding roller. [FIG. 5H] FIG. 5H is a schematic view (Part 8) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a double-feed elimination process. [FIG. 5I] FIG. 5I is a schematic view (Part 9) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a state where the rotation of the feed roller has been stopped. [FIG. 5J] FIG. 5J is a schematic view (Part 10) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a state where the hopper has been lowered. [FIG. 5K] FIG. 5K is a schematic view (Part 11) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a continuous-feed prevention process. [FIG. 5L] FIG. 5L is a schematic view (Part 12) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a vibration process. [FIG. 5M] FIG. 5M is a schematic view (Part 13) illustrating the operation when the paper S stored in the paper tray is delivered to the delivery path P1 under the control of the control portion, showing a main feed process. [FIG. 6] FIG. 6 is a flowchart showing process by the control portion to deliver the paper from the paper tray to the delivery path. [Detailed Description of Embodiments]

[0013] In the following, an embodiment of the printer according to the present invention will be described with reference to the drawings.

[0014] [Overall Configuration of Printer] FIG. 1 is a cross-sectional view taken by a vertical plane that is along the front-rear direction L and passes the center in the width direction W of a dye-sublimation thermal printer 100 (hereinafter, referred to as "printer 100").

[0015] The printer 100 shown in the drawings is an embodiment of the printer according to the present invention. The printer 100 can store both of sheet papers S (hereinafter simply referred to as papers S) pre-cut into a predetermined size, and a roll paper R (hereinafter simply referred to as paper R) formed into a roll by winding a single long sheet of paper, and can produce an output by selectively printing on either paper S or R.

[0016] The printer 100 includes a case 10, a paper tray 20, a printing 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 that houses the printing 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 body of the printer 100 includes the case 10, the printing 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. As described later, the paper tray 20 is detachably attached to the body of the printer 100. The case 10 is formed, in its front panel covering the front surface in the length direction L, with a discharge port 15 for discharging the printed paper S, R.

[0018] <Paper Tray> FIG. 2 is a perspective view showing the paper tray 20. The paper tray 20 stores a plurality of papers S (sheet papers S) stacked in the thickness direction. The paper tray 20 is attached to the body of the printer 100 to be detachable therefrom by a pull-out manner. Specifically, the paper tray 20 is disposed at the bottom of the printer 100. As indicated by a white arrow of FIG. 1, it can be removed from the body of the printer 100 by pulling out forward in the front-rear direction L. As shown in FIG. 1, the paper tray 20 detached from the body of the printer 100 is attached thereto.

[0019] As shown in FIG. 2, the paper tray 20 is formed in a box shape (tray) with a small thickness and no top plate by a bottom plate 21 on which the papers S are stacked, side plates 24, 25 rising in the thickness direction of the papers S (height direction H of the printer 100) on both sides in the width direction W, a rear plate 23 rising on the rear side in the front-rear direction L, and a front plate 22 rising on the front side in the front-rear direction L.

[0020] A front portion 21a as a part of the bottom plate 21 is formed to be pivotable upward about an axis C3 at a rear end portion of the front portion 21a. In other words, the front portion 21a serves as a hopper to raise a front portion of the papers S disposed on the bottom plate 21 when inclined upward. In the following, this front portion 21a is referred to as the hopper 21a.

[0021] The hopper 21a is driven to move vertically by a motor (not shown in the drawings) installed in the body of the printer 100. Specifically, the motor installed in the body of the printer 100 is driven by the control portion 90, and a plate 19 (see FIGS. 1 and 4) installed in the body pushes the hopper 21a upward through an opening 20A (see FIG. 1) formed in the bottom surface of the paper tray 20. Consequently, the hopper 21a is raised to take an inclined posture (indicated by a double-dotted line in FIG. 2).

[0022] The paper tray 20 includes an inclined plate 27 extending obliquely upward and forward from the upper end of the front plate 22. In other words, the inclined plate 27 includes a slope descending rearward. The inclined plate 27 is formed at its central portion in the width direction W with an opening 27d. Portions of the inclined plate 27 that are adjacent to the opening 27d are hereinafter referred to as inclined portions 27a.

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

[0024] The paper tray 20 detached from the body of printer 100 is attached to the body of printer 100, as shown in FIG. 1, by pushing the front cover member 26 into a space formed to extend in the front-rear direction L at the bottom of printer 100, from the front side to the rear in the front-rear direction L (opposite direction of the white arrow in FIG. 1). In a condition that the paper tray 20 is attached to the body of printer 100, the front cover member 26, together with the case 10, forms the front surface in the front-rear direction L of printer 100.

[0025] The paper tray 20 includes a retarding roller 84 shown in FIG. 2. The retarding roller 84 is disposed in a front space of the paper tray 20 that is formed between the front plate 22 and the front cover member 26. A part of the retarding roller 84 projects upward from the plane of inclined portions 27a through the opening 27d formed in the inclined plate 27.

[0026] Regardless of the number of papers S stored in the paper tray 20, the hopper 21a is configured to be inclined upwardly such that the topmost paper S of the papers S raised by the hopper 21a is brought into abutment with a pickup roller 81 to raise the pickup roller 81 and that an extension line from the leading edge of the paper S takes a position to hit against the rear end of the inclined plate 27 without contacting a feed roller 82.

[0027] As shown in FIG. 2, the retarding roller 84 provided in the paper tray 20 faces the inner side of the paper tray 20 from the opening 27d of the inclined plate 27 of the paper tray 20. As shown in FIG. 1, when the paper tray 20 is installed in the normal position of the body of printer 100, the retarding roller 84 is disposed to contact the feed roller 82 fixed to the body of printer 100.

[0028] <Roll-paper Storage Portion> The roll-paper storage portion 60 is formed above the paper tray 20, toward the front in the front-rear direction L. The roll-paper storage portion 60 is a portion for storing the roll paper R. In FIG. 1, the roll-paper storage portion 60 stores the roll paper R with its axis parallel with the width direction W of printer 100 and with the paper wound counterclockwise from the center toward the outer peripheral side. The roll paper R stored in the roll-paper storage portion 60 is drawn and unwound from the lower end of the roll paper R in the right direction of FIG. 1 so as to be rotated counterclockwise as shown in the drawing.

[0029] <Printing Portion> The printing portion 30 is disposed behind the roll-paper storage portion 60 in the front-rear direction L. Under the control of the control portion 90, the printing portion 30 conducts printing on the paper S, R that passes a section (printing path P3 described below) of the transport path P, which is raised in a substantially vertical direction behind the roll-paper storage portion 60.

[0030] The printing 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 a sublimation dye. The ink ribbon 32 feeds the ribbon from a delivery roll 32a to a winding roll 32b in synchronization with the transport of the paper S, R, and the sublimation dye of the ink ribbon 32 is subjected to diffusion transfer onto the paper S, R by the heat generation of the thermal head 31 in contact with the ink ribbon 32, thereby conducting printing.

[0031] The platen roller 33 is disposed on the opposite side of the ink ribbon 32 and the thermal head 31 across the paper S, R, which is transported in the printing path P3 described below. The platen roller 33 presses the paper S, R against the ink ribbon 32.

[0032] <Cutter Portion> The cutter portion 40 is disposed ahead of the roll-paper storage portion 60. The cutter portion 40 operates under the control of the control portion 90. The cutter portion 40 cuts the paper R along the width direction W that passes a section (discharge path P9 described below) of the transport path P, which extends forward from above the roll-paper storage portion 60. As described above, the cutter portion 40 cuts the roll paper R into predetermined lengths, but it can also cut unnecessary edges, etc. from the sheet paper S.

[0033] <Creasing Portion> The creasing portion 50 is disposed behind the roll-paper storage portion 60 in the front-rear direction L and between the printing portion 30 and the paper tray 20 in the height direction H. The creasing portion 50 operates under the control of the control portion 90. The creasing portion 50 forms a crease, which is a recess extending along the width direction W, on the paper S passing a section (creasing path P7 described below) extending along the front-rear direction L below the roll-paper storage portion 60. As described above, the creasing portion 50 forms a crease on the sheet paper S, but it may also form a crease on the roll paper R by controlling cutting or transport.

[0034] <Transport Path> FIG. 3 is a schematic view schematically expressing a simplification of FIG. 1 for clarifying the transport path P. The transport path P is a passage through which the paper S, R is transported by the transport portion 70, shown in FIG. 3 by dashed lines. A symbol Q shown beside the transport path P indicates the forward direction in which the paper S is fed from the paper tray 20 toward the discharge port 15, and the forward direction in which the paper R is fed from the roll-paper storage portion 60 toward the discharge port 15. A symbol -Q indicates the reverse direction which is opposite to the forward direction Q.

[0035] The transport path P includes a sheet-paper delivery path P1, a sheet-paper feeding path P2, a printing path P3, a standby path P4, a printing downstream path P5, an inversion standby path P6, a creasing path P7, a roll-paper feeding path P8, and the discharge path P9.

[0036] The sheet-paper delivery path P1 (hereinafter simply referred to as delivery path P1) is a transport path through which the papers S stored in the paper tray 20 are delivered one by one. The delivery path P1 is formed to extend obliquely upward and forward from the front end of the paper tray 20. Means for delivering the paper S from the paper tray 20 to the delivery path P1 are the pickup roller 81 and the feed roller 82, which are installed in the body of printer 100, but the retarding roller 84 provided in the paper tray 20 is also used for preventing double feed of the paper S.

[0037] When the paper S is delivered, the hopper 21a of paper tray 20 is raised. The action of delivery of the paper S is described later together with the structure of retarding roller 84.

[0038] The sheet-paper feeding path P2 (hereinafter simply referred to as feeding path P2) is a transport path following the delivery path P1. It extends upward from the front end of the delivery path P1, then turns back to extend rearward and downward in a space formed in front of the roll-paper storage portion 60, then extends rearward in a space between the roll-paper storage portion 60 and the paper tray 20, and then extends upward to a position behind the roll-paper storage portion 60.

[0039] Following the feeding path P2, the printing path P3 extends to rise from the front end of the feeding path P2 along behind the roll-paper storage portion 60 and then extends frontward to the front of above the roll-paper storage portion 60. The platen roller 33 and the thermal head 31 of the printing portion 30 are disposed to be opposed to each other across the printing path P3.

[0040] Following the printing path P3, the standby path P4 extends from the front end of printing path P3 to the front of above the roll-paper storage portion 60 and 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 reach a position just before it meets the feeding path P2.

[0041] Following the printing path P3, the printing downstream path P5 is formed to extend obliquely downward and forward from the rear end of the printing path P3 behind the roll-paper storage portion 60 to pass outside the feeding path P2.

[0042] Following the printing downstream path P5, the inversion standby path P6 is formed to extend forward in the front-rear direction L, in a space between the feeding path P2 and the paper tray 20, from the front end of printing downstream path P5, so that its front end connects to the rear end of feeding path P2. The paper S passing through the inversion standby path P6 has been already subjected to printing on its lower surface shown in the drawing. As the paper S is transported again through the feeding path P2 from the inversion standby path P6, the upper surface of paper S in the inversion standby path P6 is to be printed in the printing portion 30 when it subsequently passes through the printing path P3. Therefore, the inversion standby path P6 and the feeding path P2 form an inverting path where the paper S is inverted upside down.

[0043] Following the inversion standby path P6, the creasing path P7 is formed to extend rearward in the front-rear direction L from the rear end of the inversion standby path P6 above the paper tray 20. The creasing portion 50 is disposed in the creasing path P7.

[0044] The roll-paper feeding path P8 is formed to extend rearward from a generally bottom portion of the roll-paper storage portion 60 and then rises behind the roll-paper storage portion 60 to reach the rear end of the printing path P3.

[0045] Following the printing path P3, the discharge path P9 is formed forward in the front-rear direction L from the front end of printing path P3 above the roll-paper storage portion 60 to reach the discharge port 15. The cutter portion 40 is formed in the discharge path P9.

[0046] <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 paper S, R along the transport path P and also switches the transport path P through which it is transported. The transport portion 70 is configured by drive rollers, which are driven by motors (not shown in the drawings) controlled by the control portion 90, driven rollers with no driving force, switching members 71, 72, 73 for switching the transport path P, etc.

[0047] Of the transport portion 70, those configured by conventional drive rollers and driven rollers for feeding the paper S, R while it is interposed therebetween are omitted from the illustration and description. The transport portion 70 includes the pickup roller 81, feed roller 82 and retarding roller 84 for delivering the paper S from the paper tray 20 to the delivery path P1. These pickup roller 81, feed roller 82 and retarding roller 84 are described later.

[0048] The switching member 71 is provided at the front end of printing path P3. The switching member 71 switches between feeding the paper S, R, which has been fed through the printing path P3 in the forward direction Q, to the standby path P4 for subsequent printing, and feeding the same to the discharge path P9, thereby discharging the paper S, R. The switching of the transport path by the switching member 71 is conducted under the control of control portion 90.

[0049] The switching member 72 is provided at the rear end of the printing path P3. The switching member 72 serves to return the paper S, which has been fed through the printing path P3 in the reverse direction -Q, to the printing downstream path P5 without making it proceed to the roll-paper feeding path P8 by mistake. The switching member 72 is biased by a spring to close the roll-paper feeding path P8.

[0050] As a result, when the printed paper is the sheet paper S, the switching member 72 feeds the paper S, which has been fed through the printing path P3 in the reverse direction -Q, to the printing downstream path P5.

[0051] On the other hand, when the printed paper is the roll paper R, the switching member 72 is biased by a spring to close the roll-paper feeding path P8, but the paper R is a continuous sheet. Thus, even if the leading edge side of the paper R has reached the printing path P3, a portion connecting to the roll paper R stored in the roll-paper storage portion 60 pushes the switching member 72 open to open a passage to the roll-paper feeding path P8 against the spring biasing force. Therefore, when the paper R fed through the printing path P3 in the reverse direction -Q is rewound to the roll-paper feeding path P8, the switching member 72 can allow the paper R to be rewound to the roll-paper feeding path P8 without obstruction.

[0052] The switching member 73 is provided at the rear end of the printing downstream path P5. The switching member 73 serves as a switching valve to reliably feed the paper S, which has been transported in the reverse direction -Q after its feeding to the inversion standby path P6, to the creasing path P7 without returning it to the printing downstream path P5.

[0053] The switching member 73 is biased by a spring toward the side to feed the paper S to the creasing path P7. After printing is complete, the paper S including its rear end is disposed in the inversion standby path P6. However, during printing, the rear end of paper S remains in the printing downstream path P5. In other words, during printing, the paper S is not fed to the inversion standby path P6 up to its rear end, but its rear end remains in the printing downstream path P5.

[0054] Then, for printing the second and subsequent colors, the paper S is fed in the reverse direction -Q through the printing downstream path P5 and then is returned again to the standby path P4. The printer 100 repeats the printing operation to perform a multicolor printing or coating.

[0055] In this manner, the paper S during the multicolor printing is in a state of stretching between the inversion standby path P6 and the printing downstream path P5. In this state, the paper S presses the switching member 73 against the biasing force of the spring to the side where the paper S is allowed to pass through the printing downstream path P5, thereby making a switch to the side where the paper S is fed to the printing downstream path P5.

[0056] (Pickup Roller and Feed Roller) FIG. 4 is a partial cross-sectional view corresponding to FIG. 1, illustrating the structures and functions of the pickup roller 81, the feed roller 82, and the retarding roller 84.

[0057] The pickup roller 81, feed roller 82, and retarding roller 84 are included in the transport portion 70 that delivers the paper S from the paper tray 20 to the delivery path P1. The retarding roller 84 is not a simple driven roller, but generates a torque (reverse torque) in a direction opposite to the rotational direction to apply the brake to the rotation, thereby preventing double feed in which two or more sheets of paper are fed in an overlapped condition when delivering the paper S.

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

[0059] The pickup roller 81 and feed roller 82 are integrally formed by the arm 83. The arm 83 places the pickup roller 81 behind the feed roller 82 in the front-rear direction L. The arm 83 is disposed in a posture having a slope descending rearward as a whole such that the pickup roller 81 is below the feed roller 82 in the height direction H. The arm 83 is rotatable coaxially with the rotation axis of the feed roller 82, and is biased by a spring in a direction to press the pickup roller 81 against the papers S stored in the paper tray 20. The distance between the rotation axis of the pickup roller 81 and that of the feed roller 82 is, for example, 20 mm.

[0060] The pickup roller 81 and the feed roller 82 are driven by a single motor controlled under the control of the control portion 90. Therefore, the pickup roller 81 and the feed roller 82 rotate in a forward rotational direction N and a reverse rotational direction -N or stop in a synchronous manner.

[0061] (Retarding Roller) As mentioned above, the retarding roller 84 is provided in the paper tray 20. As shown in FIG. 4, when the paper tray 20 is attached to the normal position of the body of the printer 100, the retarding roller 84 is disposed to contact a front lower portion of the feed roller 82.

[0062] The paper S is sandwiched between the retarding roller 84 and the feed roller 82 as a drive roller. The retarding roller 84 is a driven roller, and the retarding roller 84 itself does not drive anything. As the paper S sandwiched between the retarding roller 84 and the feed roller 82 proceeds in the forward direction Q by the drive force of the feed roller 82, the retarding roller 84 rotates thereby in the forward rotational direction N. As the paper S proceeds in the reverse direction -Q, it rotates thereby in the reverse rotational direction -N.

[0063] When the retarding roller 84 rotates around an axis C2, it generates a torque (reverse torque) in the opposite direction to its rotation, thereby applying a brake to the rotation. The retarding roller 84 is configured such that the reverse torque generated when rotating in the reverse rotational direction -N (rotational direction to feed the paper S in the reverse direction -Q) is smaller than that generated when rotating in the forward rotational direction N (rotational direction to feed the paper S in the forward direction).

[0064] <Control Portion> The control portion 90 is disposed above the paper tray 20 and behind the printing portion 30. The control portion 90 includes paper sensors that detect the paper S, R passing predetermined positions of the transport path P. Although the paper sensors are provided at multiple positions, only the paper sensor 92 provided in the delivery path P1 is described, and descriptions and explanations of the other paper sensors are omitted.

[0065] The control portion 90 controls each operation of the printing portion 30, the cutter portion 40, the creasing portion 50, and the transport portion 70. The timing of each operation is mainly controlled by the detection results from the paper sensors.

[0066] (Control for Paper S (Sheet Paper S)) The printer 100 operates as follows for the paper S passing through the transport path P. Firstly, the control portion 90 controls the pickup roller 81, the feed roller 82, and the hopper 21a to deliver the paper S stored in the paper tray 20 to the delivery path P1 in the forward direction Q. Details of the control by the control portion 90 when the paper S is delivered from the paper tray 20 will be described later.

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

[0068] Next, while the paper S is fed to the standby path P4 in the reverse direction -Q and then to the printing path P3 in the reverse direction -Q, the control portion 90 controls the printing portion 30 to conduct printing on one surface of the paper S (surface facing the thermal head 31). When the printing portion 30 conducts a multicolor printing on the paper S or a coating after the printing, the control portion 90 repeats the feeding of the paper S in the printing path P3 and the standby path P4 in the forward and reverse directions Q, -Q.

[0069] The control portion 90 feeds the paper S printed in the printing portion 30 to the printing downstream path P5 in the forward direction Q (corresponding to the reverse direction -Q in the printing path P3), then to the inversion standby path P6 in the forward direction Q, then to the feeding path P2 in the forward direction Q, and then to the printing path P3 in the forward direction Q. As mentioned above, the control portion 90 inverts the front and back sides of the paper S by passing the paper S through the inversion standby path P6 and the feeding path P2.

[0070] When the printer 100 finishes with printing only one surface of the paper S, the control portion 90 subsequently feeds the paper S to the discharge path P9 in the forward direction Q and then discharges it from the discharge port 15 to the outside of the printer 100 and completes the process.

[0071] When the printer 100 conducts printing both surfaces of the paper S, the paper S fed to the printing path P3 in the forward direction Q is fed to the standby path P4 in the forward direction Q.

[0072] While the control portion 90 subsequently feeds the paper S to the standby path P4 in the reverse direction -Q and then to the printing path P3 in the reverse direction -Q, the printing portion 30 prints the other surface of the paper S (surface facing the thermal head 31). When the printing portion 30 conducts a multicolor printing on the paper S or a coating after the printing, the control portion 90 repeats the feeding in the printing path P3 and the standby path P4 in the forward and reverse directions Q, -Q.

[0073] The control portion 90 subsequently feeds the paper S printed in the printing portion 30 to the printing downstream path P5 in the forward direction Q, then to the inversion standby path P6 in the forward direction Q, then to the feeding path P2 in the forward direction Q, then to the printing path P3 in the forward direction Q, then to the discharge path P9 in the forward direction Q. Then, the control portion 90 discharges it from the discharge port 15 to the outside of the printer 100 and completes the process.

[0074] In the case of single-sided printing, when the paper S is to be creased, the control portion 90 feeds the paper S, after the single-sided printing, transported into the inversion standby path P6 in the reverse direction -Q within the inversion standby path P6, and then feeds the paper S in the reverse direction -Q toward the creasing path P7, where the paper S is creased by the creasing portion 50.

[0075] In the case of double-sided printing, when the paper S is to be creased, the control portion 90 feeds the paper S, after the double-sided printing, transported into the inversion standby path P6 in the reverse direction -Q within the inversion standby path P6, and then feeds the paper S in the reverse direction -Q toward the creasing path P7, where the paper S is creased by the creasing portion 50 under the control of the control portion 90.

[0076] (Control for Paper R (Roll Paper R)) For the paper R passing through the transport path P, the printer 100 operates as follows. Firstly, the control portion 90 controls the transport portion 70 to deliver the paper R stored in the roll-paper storage portion 60 to the roll-paper feeding path P8 in the forward direction Q. As the roll paper R is delivered in the forward direction Q, it is unwound from the roll.

[0077] Next, the control portion 90 feeds the paper R to the printing path P3 in the forward direction Q and then to the standby path P4 in the forward direction Q.

[0078] Next, the control portion 90 returns the paper R to the standby path P4 in the reverse direction -Q. Then, while returning it to the printing path P3 in the reverse direction -Q, it conducts printing on one surface of the paper R (surface facing the thermal head 31) by controlling the printing portion 30. When the paper R is returned in the reverse direction -Q, it is rewound onto the roll.

[0079] When the printing portion 30 conducts a multicolor printing on the paper R or a coating after the printing, the control portion 90 repeats the feeding of the paper R in the printing path P3 and the standby path P4 in the forward direction Q and the reverse direction -Q.

[0080] The control portion 90 subsequently feeds the paper R printed in the printing portion 30 to the printing path P3 in the forward direction Q, then feeds the paper R to the discharge path P9 in the forward direction Q, then controls the cutter portion 40 to cut the paper R to a predetermined length, and then discharges the printed paper R separated from the roll by the cutting from the discharge port 15 to the outside of the printer 100.

[0081] The portion of the paper R connected to the roll after the printed portion is cut is rewound onto the roll in the roll-paper storage portion 60 by the control portion 90, and is thereby returned in the reverse direction -Q to the discharge path P9, the printing path P3, and the roll-paper feeding path P8.

[0082] (Details of Controlling Paper Delivery from Paper Tray by Control Portion) FIGS. 5A to 5M are schematic views illustrating the operation when the paper S stored in the paper tray 20 is delivered to the delivery path P1 under the control of the control portion 90. FIG. 6 is a flowchart showing a process to deliver the paper S from the paper tray 20 to the delivery path P1.

[0083] Next, the control by the control portion 90 when delivering the paper S stored in the paper tray 20 to the delivery path P1 will be described in detail with reference to FIGS. 5A to 5M and 6.

[0084] (Separation Process) In the state shown in FIG. 5A where the papers S are stored in the paper tray 20, the process for delivering the paper S to the delivery path P1 is executed by the control portion 90 driving a motor provided in the body of the printer 100, raising the plate 19 by the motor, and pushing the hopper 21a upward as shown in FIG. 5B. As a result, the front portions of all the papers S stored in the paper tray 20 are raised, thereby bringing the topmost paper S1 into contact with the pickup roller 81.

[0085] Here, when the direction in which the paper S is fed toward the delivery path P1 is defined as the forward direction Q, the rotational directions of the pickup roller 81, the feed roller 82 and the retarding roller 84, which correspond to feeding the paper S in the forward direction Q, are each defined as the forward rotational direction N. The rotational directions of the pickup roller 81, the feed roller 82 and the retarding roller 84, which correspond to feeding the paper S in the reverse direction -Q opposite to the forward direction Q, are each defined as the reverse rotational direction -N.

[0086] Then, as shown in FIG. 5C, the control portion 90 controls the pickup roller 81 to rotate in the reverse rotational direction -N. The control portion 90 drives the pickup roller 81 by a rotation angle corresponding to feeding the paper S, which is in contact with the outer circumferential surface of the pickup roller 81, by a distance of 10 mm in the reverse direction -Q.

[0087] As a result, the topmost paper S1, which is in contact with the pickup roller 81, tries to move in the reverse direction -Q by receiving the torque from the pickup roller 81. However, the rear end portion in the front-rear direction of the paper S1 does not move due to its abutment with the paper tray 20. Therefore, the paper S1 bends upward in an unrestricted section between the front end portion in contact with the pickup roller 81 and the rear end portion in abutment with the paper tray 20.

[0088] Here, the second paper S2, which is in contact with the topmost paper S1 and is stacked immediately below the same, is not in contact with the pickup roller 81, so that it does not receive the torque from the pickup roller 81 to move in the reverse direction -Q. Thus, the topmost paper S1, which receives the torque from the pickup roller 81, is raised, but the second paper S2 is not. This forms a gap between the topmost paper S1 and the second paper S2 as shown in FIG. 5C to make an air layer.

[0089] As a result, it makes a separated condition between the topmost paper S1 and the second paper S2, thereby producing a condition easy to separate them from each other. This can suppress the occurrence of double feed. Thus, the process to form a gap between the topmost paper S1 and the second paper S2 is hereinafter referred to as separation process. In the printer 100 of the present embodiment, the control portion 90 need not always conduct the separation process, and it is also possible to omit the separation process.

[0090] (Backlash Adjustment Process) Then, as shown in FIG. 5D, the control portion 90 controls the hopper 21a to lower. This makes all the papers S, which are stored in the paper tray 20, away from the pickup roller 81.

[0091] Then, as shown in FIG. 5E, while the hopper 21a is lowered, the control portion 90 rotates the pickup roller 81 in the forward rotational direction N. The control portion 90 drives the pickup roller 81 by a rotation angle corresponding to feeding the paper S, which is in contact with the outer circumferential surface of the pickup roller 81, by a distance of 20 mm in the forward direction Q.

[0092] This makes backlash in the rotational direction of the pickup roller 81 and the feed roller 82 shift to the rear side in the forward rotational direction N. Thus, at the subsequent rotation in the forward rotational direction N, the driving with no backlash in the rotational direction becomes possible, thereby achieving the effect of accurately feeding the paper S1 in the forward direction Q. Thus, the process, in which the control portion 90 eliminates the backlash in the forward rotational direction N by idling the pickup roller 81 and feed roller 82 in the forward rotational direction N after the separation process, is hereinafter referred to as the backlash adjustment process. In the printer 100 of the present embodiment, the control portion 90 need not always conduct the backlash adjustment process, and it is also possible to omit the backlash adjustment process.

[0093] (Double-feed Elimination Process) Then, as shown in FIG. 5F, the control portion 90 controls the hopper 21a to rise, so that the topmost paper S1 is brought into contact with the pickup roller 81. Then, the control portion 90 makes the pickup roller 81 rotate in the forward rotational direction N, thereby moving the topmost paper S1 in the forward direction Q.

[0094] When the topmost paper S1 is fed in the forward direction Q, the leading edge of the paper S is brought into abutment with the rear end of the inclined plate 27. Since the direction of the leading edge of the paper S is inclined upward, the paper S1 bends such that its leading edge escapes toward the upper side of the inclined plate 27. Then, the leading edge of the paper S1 is brought into contact with the retarding roller 84, which is rotating forward in response to the feed roller 82, and then is sandwiched between the feed roller 82 and the retarding roller 84.

[0095] Here, in case that the second paper S2 is subjected to double feed with the topmost paper S1 in an overlapped manner, the leading end of the topmost paper S1 is brought into abutment with the rear end of the inclined plate 27 to make the bending in an upward escaping manner, but the second paper S2 hardly bends simultaneously with the topmost paper S1. This makes it difficult for the second paper S2 to reach the retarding roller 84.

[0096] The front edge portion of the topmost paper S1 that passed the pickup roller 81 is guided by the surfaces of the inclined portions 27a of the inclined plate 27. Then, as shown in FIG. 5G, it is sandwiched between the feed roller 82 and the retarding roller 84 and then is fed in the forward direction Q toward the delivery path P1 by receiving torque from the rotation of feed roller 82 in the forward rotational direction N.

[0097] The paper sensor 92 is disposed at a predetermined position of the delivery path P1. When the paper sensor 92 detects the passage of the front edge portion of the topmost paper S1 that is delivered to the delivery path P1, the control portion 90 temporarily stops the rotation of feed roller 82 in the forward rotational direction N.

[0098] The paper sensor 92 is disposed at a distance of, for example, 30 mm along the delivery path P1 in the forward direction Q from the position where the feed roller 82 and the retarding roller 84 contact each other (at a distance of, for example, 50 mm from the pickup roller 81). The distance of 30 mm at which the paper sensor 92 is disposed is one example. The position of the paper sensor 92 is not limited to that at a distance of 30 mm.

[0099] Here, a situation will be described in which a double feed occurs, where the second paper S2 overlaps the topmost paper S1 as shown in FIG. 5H, despite the separation process performed by the control portion 90 as shown in FIGS. 5B and 5C.

[0100] In the double feed situation, when the control portion 90 rotates the pickup roller 81 in the forward rotational direction N to move the topmost paper S1 in the forward direction Q (see FIG. 5F), factors such as static electricity cause the second paper S2 to adhere to the topmost paper S1 and to move in the forward direction Q together with the topmost paper S1. Thus, as shown in FIG. 5H, the topmost paper S1 and the second paper S2 reach a position where they are sandwiched between the feed roller 82 and the retarding roller 84.

[0101] Even when the double feed shown in FIG. 5H occurs, the control portion 90 controls the feed roller 82 to rotate in the forward rotational direction N. Friction occurs between the feed roller 82 and the upper surface of the topmost paper S1 in contact with the feed roller 82, due to sandwiching between the retarding roller 84 and the feed roller 82. This causes the topmost paper S1 to be fed in the forward direction Q by the torque resulting from the friction with the feed roller 82, in the same manner as in a case without a double feed.

[0102] Then, when the paper sensor 92 detects the passage of the front end portion of the topmost paper S1 delivered to the delivery path P1, the control portion 90 temporarily stops the rotation of the feed roller 82 in the forward rotational direction N.

[0103] Meanwhile, the second paper S2 receives a propulsive force in the forward direction Q due to a frictional force generated by the contact of topmost paper S with its upper surface. However, its lower surface contacts the retarding roller 84, which generates a counter-torque in a direction opposite to the rotational direction. This counter-torque causes a force in the reverse direction -Q exceeding the frictional force in the forward direction Q. This causes the second paper S2 to stop in a state where it contacts the retarding roller 84.

[0104] As a result, the topmost paper S can be separated from the second paper S and fed in the forward direction Q, thereby eliminating double feed. Thus, the process in which the control portion 90 feeds the topmost paper S1 in the forward direction Q from a condition that the topmost paper S1 contacts the pickup roller 81, until it is detected by the paper sensor 92, by passing through between the feed roller 82 and the retarding roller 84, thereby separating the second paper S2 from the topmost paper S1, is hereinafter referred to as double-feed elimination process.

[0105] The front end portion of the topmost paper S1, which reaches the position of the paper sensor 92, is offset by approximately 30 mm in the forward direction Q from the front end portion of the second paper S2, which is stopped in a condition where its front end is in contact with the retarding roller 84. When the position of paper sensor 92 is disposed at a distance of X mm along the delivery path P1 in the forward direction Q from the position where the feed roller 82 and the retarding roller 84 are in contact with each other, the front end portion of the topmost paper S1 is offset by approximately X mm in the forward direction Q from the front end portion of the second paper S2.

[0106] (Continuous-feed prevention process) Next, the control portion 90 performs control to prevent continuous feeding in which the second paper S2 is fed without a predetermined interval immediately after the topmost paper S1 is fed. In other words, the printer 100 eliminates double feed through the control by the control portion 90. However, when the rear end portion of the topmost paper S1 finishes passing the feed roller 82 in the state shown in FIG. 5H, the feed roller 82 contacts the upper surface of the second paper S2. Consequently, the feed roller 82 applies torque in the forward direction Q to the upper surface of the second paper S2. This starts feeding the second paper S2 in the forward direction Q. As a result, continuous feeding occurs, in which the interval between the rear end of the topmost paper S1 and the front end of the second paper S2 becomes narrow.

[0107] Thus, in a state where the rotation of the feed roller 82 in the forward rotational direction N is temporarily stopped as shown in FIG. 5I, the control portion 90 controls the hopper 21a to lower as shown in FIG. 5J. At this time, since the topmost paper S1 and the second paper S2 are sandwiched between the feed roller 82 and the retarding roller 84, they do not fall into the paper tray 20, but all the papers S stacked below the second paper S2 fall into the paper tray 20.

[0108] Then, while the hopper 21a is lowered, as shown in FIG. 5K, the control portion 90 controls the feed roller 82 to rotate in the reverse rotational direction -N. The rotation in the reverse rotational direction -N corresponds to a rotation angle equivalent to feeding the topmost paper S1, which is in contact with the feed roller 82, in the reverse direction -Q by a distance of, for example, approximately 22 mm.

[0109] Here, the retarding roller 84 is set such that its counter-torque against the rotation in the reverse rotational direction -N is smaller than its counter-torque against the rotation in the forward rotational direction N. Furthermore, this counter-torque against the reverse rotational direction -N is set smaller than the frictional force received by the second paper S2 from the topmost paper S fed in the reverse direction -Q. As a result, when the second paper S2 is about to move in the reverse direction -Q by the frictional force between the same and the topmost paper S1, the retarding roller 84 rotates in the reverse rotational direction -N in response to the movement of the second paper S2.

[0110] In this manner, the topmost paper S1 and the second paper S2, both of which are sandwiched between the feed roller 82 and the retarding roller 84, move together in the reverse direction -Q. The topmost paper S1 is fed approximately by 22 mm in the reverse direction - Q to be sandwiched between the feed roller 82 and the retarding roller 84. The second paper S2, before being fed by approximately 22 mm in the reverse direction -Q, falls into the paper tray 20, similar to the other papers stacked below the second paper S2.

[0111] It is sufficient that the rotation angle of the feed roller 82 in the reverse rotational direction -N is an angle that, when the topmost paper S1 is fed in the reverse direction -Q, results in the topmost paper S1 being sandwiched between the feed roller 82 and the retarding roller 84, and that results in the second paper S2 being fed in the reverse direction -Q beyond the position where it would be sandwiched between the feed roller 82 and the retarding roller 84 so as to be separated from the feed roller 82 and the retarding roller 84.

[0112] The distance of approximately 22 mm is one exemplary distance that achieves a condition of the topmost paper S1 sandwiched between the feed roller 82 and the retarding roller 84 and that is sufficient for the second paper S2 to reliably move away from the feed roller 82 and the retarding roller 84. It is not limited to the distance of approximately 22 mm. For example, a distance of 10 mm to 25 mm may also be applied.

[0113] As described above, under the control of the control portion 90, the second paper S2 falls into the paper tray 20. Therefore, in this state where the hopper 21a is lowered, even if the feed roller 82 is rotated in the forward rotational direction N, the second paper S2 is not fed in the forward direction, thereby preventing the continuous feeding. Therefore, the printer 100 can eliminate double feed of paper S and prevent continuous feeding of paper S under the control of the control portion 90.

[0114] In this manner, the control portion 90 conducts a process of separating the second paper S, which is in contact with the retarding roller 84, from the same by rotating the feed roller 82 in the reverse rotational direction -N after the double-feed elimination process. This process is hereinafter referred to as the continuous-feed prevention process.

[0115] (Vibration Process) Then, as shown in FIG. 5L, the control portion 90 controls the hopper 21a to rise and lower in succession at least once. This operation of raising and lowering the hopper 21a is an operation for reliably returning the second paper S2 into the paper tray 20.

[0116] In other words, the second paper S2 does not return to the paper tray 20, in a state where the second paper S2 lost a propulsive force in the reverse direction -Q immediately after the front end portion in the forward direction Q (rear end portion in the reverse direction -Q) of the second paper S2 separated from the retarding roller 84 when the second paper S2 was fed in the reverse direction -Q by the rotation of the feed roller 82 in the reverse rotational direction -N as shown in FIG. 5K, and where the second paper S2 stopped with its front end portion in the forward direction Q (rear end portion in the reverse direction -Q) resting on the inclined portion 27a behind the retarding roller 84.

[0117] When the control portion 90 starts controlling the feed roller 82 to rotate in the forward rotational direction N while the front end portion in the forward direction Q (rear end portion in the reverse direction -Q) of the second paper S2 rests on the inclined portion 27a behind the retarding roller 84, the second paper S2 may advance in the forward direction Q due to friction between the same and the topmost paper S1, thereby contacting the retarding roller 84 again and causing continuous feeding.

[0118] Thus, the control portion 90 makes the hopper 21a rise and lower, thereby applying vibration to all the papers S on the hopper 21a. This vibration slides down the front end portion in the forward direction (rear end portion in the reverse direction) of the second paper S2 resting on the inclined portion 27a behind the retarding roller 84, from the inclined portion 27a and then returns the second paper S2 into the paper tray 20. In this manner, the control portion 90 makes the hopper 21a rise and lower to apply vibration to the papers S after the continuous-feed prevention process. This process is hereinafter referred to as vibration process.

[0119] The control portion 90 may omit the vibration process, when the gradient (inclination) relative to the horizontal direction of the inclined portion 27a of the inclined plate 27 is set to a degree such that the second paper S reliably slides down the inclined portion 27a under its own weight immediately after the front end portion in the forward direction Q of the second paper S moved away from the retarding roller 84.

[0120] The gradient (inclination) relative to the horizontal direction of the inclined portion 27a, which allows the second paper S to reliably slide down the inclined portion 27a under its own weight immediately after the front end portion in the forward direction Q of the second paper S moved away from the retarding roller 84, is preferably 25 degrees or greater as one example, and is more preferably 35 degrees or greater.

[0121] (Standby Process) After controlling the hopper 21a to rise and lower, the control portion 90 stands by for 200 milliseconds. This standing by is set as an action time required for the second paper S to return to the paper tray 20 following the rising and lowering of the hopper 21a.

[0122] Thus, it may be set to be shorter than 200 milliseconds, when the time required for the second paper S to return to the paper tray 20 after the rising and lowering of the hopper 21a has been experimentally determined as being shorter than 200 milliseconds. It may be set to longer than 200 milliseconds, when the time has been experimentally determined as being longer than 200 milliseconds. Thus, the process where the control portion 90 stands by without performing any operation for a predetermined time after the vibration process and before the next process is hereinafter referred to as a standby process. When the control portion 90 omits the vibration process, it can also omit the standby process.

[0123] (Main feed process) As shown in FIG. 5M, after standing by for 200 milliseconds, the control portion 90 delivers the topmost paper S1 in the forward direction Q to the delivery path P1, similar to no double-feed situation shown in FIG. 5G, in a state where double feed and continuous feeding have been eliminated, by rotating the feed roller 82 in the forward rotational direction N while the hopper 21a is still lowered. Thus, the process where the control portion 90 newly delivers the paper S1 in the forward direction Q to the delivery path P1 after the double-feed elimination process and the continuous-feed prevention process is hereinafter referred to as main feed process.

[0124] FIGS. 5H to 5M describe the process in a state where double feed of the papers S is occurring. Since the printer 100 does not have an element for detecting whether double feed is occurring or not, the control portion 90 always executes the double-feed elimination process and the continuous-feed prevention process as a series of steps, regardless of whether double feed is actually occurring or not. However, in a printer 100 that has an element for detecting whether double feed is occurring or not, the control portion 90 executes the double-feed elimination process and the continuous-feed prevention process only when the detecting element detects that double feed is occurring. When the detecting element does not detect that double feed is occurring, the control portion 90 can omit the double-feed elimination process and the continuous-feed prevention process.

[0125] If the printer 100 includes an element for detecting whether or not continuous feeding occurs, the control portion 90 executes the continuous-feed prevention process only when it detects the occurrence of continuous feeding. When it does not detect the occurrence of continuous feeding, the control portion 90 can omit the continuous-feed prevention process.

[0126] In the above description of the process performed by the control portion 90, when the pickup roller 81 is rotated or stopped, the feed roller 82 is also rotated or stopped in synchronization with the pickup roller 81. Similarly, when the feed roller 82 is rotated or stopped, the pickup roller 81 is also rotated or stopped in synchronization with the feed roller 82. However, to avoid redundant explanations, the description focuses on rotating or stopping the pickup roller 81 only or the feed roller 82 only.

[0127] As described above in detail, as shown in FIG. 6, in the printer 100 of the present embodiment, the control portion 90 performs the separation process, the backlash adjustment process, the double-feed elimination process, the continuous-feed prevention process, the vibration process, the standby process, and the main feed process. As a result, when the paper S is fed from the paper tray 20 in the forward direction Q to the delivery path P1, the printer 100 can eliminate, prevent, or suppress double feed where the papers S are fed in an overlapped manner, and can prevent or suppress continuous feeding where the next paper S2 is fed without having a predetermined interval between the same and the previously fed paper S1.

[0128] (Retry Process) As shown in FIG. 5I, the control portion 90 in the printer 100 of the present embodiment stops the rotation of the feed roller 82 in the forward rotational direction N in the double-feed elimination process, based on the result obtained by detecting the front end portion in the forward direction Q of the paper S1, which is sandwiched between the feed roller 82 and the retarding roller 84, by the paper sensor 92 provided in the delivery path P1.

[0129] The paper sensor 92 is disposed at a position of 50 mm from the pickup roller 81. Therefore, as shown in FIG. 5F, the paper sensor 92 is originally supposed to detect the front end portion in the forward direction Q of the paper S1, when the paper S1 has been fed by the distance of 50 mm in the forward direction Q by rotating the pickup roller 81 in the forward rotational direction N after raising the hopper 21a.

[0130] However, when the paper sensor 92 fails to detect the paper S1, even after the control portion 90 has performed the control to feed the paper S1 in the forward direction Q by a distance exceeding 50 mm by rotating the pickup roller 81 in the forward rotational direction N after raising the hopper 21a, it can be considered that the paper S1 was not properly fed by the pickup roller 81 in the double-feed elimination process.

[0131] Thus, the control portion 90 performs the control in the double-feed elimination process to feed the paper S1 in the forward direction Q by a distance of, for example, 80 mm exceeding the distance of 50 mm by rotating the pickup roller 81 and the feed roller 82 in the forward rotational direction N after raising the hopper 21a (see FIGS. 5E to 5I). If the paper sensor 92 still fails to detect the paper S1, the pickup roller 81 and the feed roller 82 are stopped.

[0132] Then, the control portion 90 controls the hopper 21a to lower and controls the pickup roller 81 and the feed roller 82 to rotate in the reverse rotational direction -N. This control returns the topmost paper S1 (and the second paper S2 in the double feed) to a position in the reverse direction -Q beyond the pickup roller 81 then into the paper tray 20, even when the front end portion of the topmost paper S1 is at a position before the paper sensor 92 in the forward direction Q with respect to the position of the feed roller 82 and retarding roller 84.

[0133] Then, the control portion 90 performs a vibration by raising and lowering the hopper 21a one or more times to stabilize the papers S within the paper tray 20.

[0134] In this manner, when the paper sensor 92 does not detect the paper S1 in the double-feed elimination process, the control portion 90 rotates the pickup roller 81 and the feed roller 82 in the reverse rotational direction -N to once return the paper S to the paper tray 20, and then vibrates the hopper 21a. This process is called a retry process. However, the control portion 90 may omit the vibration in the retry process.

[0135] After the control portion 90 performs the retry process, the printer 100 conducts the separation process, the backlash adjustment process, the double-feed elimination process, the continuous-feed prevention process, the vibration process, the standby process, and the main feed process. As a result, the printer 100 of the present embodiment can return the process after the double-feed elimination process to normal one. The printer 100 may also omit the backlash adjustment process, the vibration process, and the standby process, after the retry process performed by the control portion 90.[Cross-reference to Related Application]

[0136] The present application is based upon and claims the benefit of priority from Japanese Patent Application No. 2023-105689 filed to the Japan Patent Office on June 28, 2023, the entire disclosure of which is incorporated in the present specification by reference.

Claims

1. A printer comprising: a pickup roller and a feed roller that are fixed to a body of the printer and are configured to rotate synchronously; a paper tray that is configured to store a plurality of sheet papers and to move a hopper up and down, the hopper being a part of a bottom plate of the paper tray; a retarding roller that is configured to contact the feed roller and to transport sheet paper stored in the paper tray such that the sheet paper is sandwiched between the retarding roller and the feed roller, with the paper tray attached to the body of the printer; and a control portion that is configured to control operations of the pickup roller, the feed roller, and the hopper, wherein the control portion is configured to perform: (1) a double-feed elimination process, the double-feed elimination process performed by rotating the pickup roller in a forward rotational direction corresponding to a forward direction of the paper to feed the topmost paper in the forward direction, and feed the topmost paper in the forward direction while being sandwiched between the feed roller and the retarding roller, thereby separating a second paper, fed in an overlapped condition with the topmost paper, from the topmost paper; (2) a continuous-feed prevention process, which is performed after the double-feed elimination process, the continuous-feed prevention process performed by rotating the feed roller in a reverse rotational direction, which is opposite to the forward rotational direction, while the hopper is lowered, thereby separating the second paper from the retarding roller; and (3) a main feed process, which is performed after the continuous-feed prevention process, the main feed process performed by rotating the feed roller in the forward rotational direction, thereby feeding the topmost paper.

2. The printer according to claim 1, wherein the control portion is configured to perform (0) a separation process before the double-feed elimination process, the separation process being performed by raising the hopper so that the topmost paper stored in the paper tray is brought into contact with the pickup roller, and rotating the pickup roller in a reverse rotational direction, which corresponds to a direction opposite to the forward direction of the paper, thereby making a separation between the topmost paper and the second paper.

3. The printer according to claim 1, wherein the control portion is configured to perform (4) a vibration process after the continuous-feed prevention process and before the main feed process, the vibration process being performed by raising and lowering the hopper,4. The printer according to claim 3, wherein the control portion is configured to perform (5) a standby process after the vibration process and before the main feed process, the standby process being performed by standing by with no operation for a predetermined time.

5. The printer according to claim 2, wherein the control portion is configured to perform (6) a backlash adjustment process after the separation process, and before the double-feed elimination process, the backlash adjustment process being performed by idling the pickup roller and the feed roller in the forward rotational direction while the hopper is lowered.

6. The printer according to any one of claims 1 to 5, further comprising a paper sensor that is configured to detect a front end portion in the forward direction of the paper fed in the forward direction with the paper sandwiched between the feed roller and the retarding roller, wherein the control portion is configured to perform: (7) a retry process, the retry process being performed when the paper sensor does not detect the front end portion of the topmost paper in a condition that the topmost paper is fed by a predetermined distance in the forward direction while being sandwiched between the feed roller and the retarding roller in the double-feed elimination process, and the retry process being performed by stopping the rotation of the feed roller, lowering the hopper, and rotating the feed roller in the reverse rotational direction, thereby returning the topmost paper to the paper tray; and wherein the control portion is configured to further perform the double-feed elimination process, the continuous-feed prevention process, and the main feed process after the retry process.

7. The printer according to claim 6, wherein the control portion is configured to perform a vibration process after the topmost paper is returned to the paper tray in the retry process, the vibration process being performed by raising and lowering the hopper.

8. The printer according to claim 1, further comprising a paper sensor that is configured to detect a front end portion in the forward direction of the paper fed in the forward direction with the paper sandwiched between the feed roller and the retarding roller, wherein the control portion is configured to perform: (7) a retry process, the retry process being performed when the paper sensor does not detect the front end portion of the topmost paper in a condition that the topmost paper is fed by a predetermined distance in the forward direction while being sandwiched between the feed roller and the retarding roller in the double-feed elimination process, and the retry process being performed by stopping the rotation of the feed roller, lowering the hopper, and rotating the feed roller in the reverse rotational direction, thereby returning the topmost paper to the paper tray; and wherein the control portion is configured to further perform the double-feed elimination process, the continuous-feed prevention process, and the main feed process after the retry process.

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