JP2000302282A - Printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly execute conveying of paper to a printing gap, by correcting a skew with an end of paper fed by a conveying roller pair colliding against a paper tilt (skew) correcting stopper, and correcting a degree of press contact force of a driven roller relating to a drive roller by the paper conveying roller pair. SOLUTION: Paper, for tilting a tip edge, makes a leading side first collide against an impeding piece of a skew correcting stopper. However, six arranged first paper conveying roller pairs 8 increase a slip with paper in accordance with the paper conveying roller pair 8 in a side impeding movement by collision, to continue rotation, and a skew is corrected. Here, press contact force relating to a drive roller 12 of a driven roller 13 in the first paper conveying roller pair 8 is properly selected by swiveling a movable member 21, so as to prevent paper from deflecting even when the paper conveying roller pair 8, while sliding between itself and the paper, gives feeding force to the paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus provided with a paper transport mechanism for nipping paper between a pair of transport rollers and feeding the paper by frictional force.

[0002]

2. Description of the Related Art In a printing apparatus, a paper transport mechanism for pressing a driven roller against a drive roller (a pair of transport rollers) and sandwiching and transporting a sheet between them is often used. The paper transport mechanism feeds the paper by the frictional force between the paper and the roller, and the force for feeding the paper is determined by the degree of the pressing force of the driven roller against the drive roller. However, conventionally, in a single printing apparatus, the degree of the pressing force according to the paper (standard paper) is selected on the assumption that the paper (standard paper) will be used most in the printing apparatus. When a paper thicker than the standard comes, the driven roller compresses the buffer spring to escape, but no special measure is taken for the paper thinner than the standard.

On the other hand, in a paper transport mechanism of a printing apparatus, a stopper for skew correction is provided upstream of the platen in the paper transport direction, and the leading edge of the paper collides with the stopper to skew the paper relative to the transport direction (skew). ) Is often provided. This mechanism provides a slip between the roller and the paper so that the leading edge of the slanted paper collides with the skew correction stopper, and the other side collides with the skew correction stopper while feeding on that side is stopped. By feeding the paper, the inclination of the paper is corrected. In order for the skew of the sheet to be corrected normally, the sheet needs to have a resistance (tension) enough to withstand the sending-out force of the sheet conveying roller pair that exerts a frictional force while sliding, but not to bend. However, if the paper is thinner than the standard paper or has a high coefficient of friction, the paper feed roller pair's feeding force will be stronger than the paper's resistance (tension). It often bends and bends, and the skew correction often ends abnormally. Conversely, if the feeding force of the paper transport roller pair is weakened in accordance with the skew correction, the resistance to the passage of the paper in the print gap between the platen and the print head is greater than that of the others. Becomes difficult.

[0004] For this reason, utility model registration No. 2508855
In the printing apparatus described in Japanese Patent Application Laid-Open Publication No. H11-209, a soft auxiliary roller 9 made of sponge or the like is attached to the outer periphery of a paper feed roller 1 (driven roller) pressed against a feed roller 5 (drive roller), and the paper is transported by a paper transport roller pair. The feeding force of the roller is reduced by the auxiliary roller up to the stopper for skew correction.
The paper feed roller 1 is strongly pressed against the auxiliary roller 9 so that the auxiliary roller 9 is crushed, and the paper is transported with a strong feeding force. However, this configuration only weakens the paper transport force before the skew correction and returns to the normal transport force after the skew correction. It does not provide a solution when the frictional force between the paper and the paper changes (change in the friction coefficient of the paper surface).

[0005]

SUMMARY OF THE INVENTION The present invention relates to a printing apparatus provided with a paper transport mechanism capable of correcting skew and properly transporting a paper to a print gap even if the thickness and the surface friction coefficient vary depending on the type of paper. To provide

[0006]

A printing apparatus includes a main body frame, a paper transport table, a platen, a print head, a paper transport roller pair, and a skew correction stopper. The paper transport table is provided with a paper transport surface and is fixed to the main body frame, and forms a straight paper transport path on the paper transport surface. The platen is arranged so as to be exposed from the sheet conveying surface of the sheet conveying table to the sheet conveying path, and the print head is arranged to face the platen. The sheet transport roller pair sandwiches and feeds a sheet between a pair of rollers, and generally includes a driving roller and a driven roller pressed against the roller, and a plurality of pairs are provided in the sheet width direction. The skew correction stopper is provided between the platen and the pair of transport rollers in the transport direction of the paper, and can advance and retreat to the paper transport path. As a result, the edge of the sheet sent by the pair of conveyance rollers collides with the skew correction stopper, and the skew is corrected.Then, the skew correction stopper retreats from the sheet conveyance path, and the skew-corrected sheet is sent to the platen. Sent.

[0007] Each pair of paper transport rollers can adjust the force of the driven roller against the drive roller to adjust the force for nipping and sending the paper according to the type of paper. Normally, the drive roller is supported by the paper carrier, the driven roller is rotatably supported by the holder and the holder is swingably supported by the body frame, and a coil spring or the like is provided between the holder and the body frame. A biasing member is provided. The driven roller is pressed against the driving roller by the biasing member. To bias the holder, a movable member may be supported on the main body frame, and a biasing member may be disposed between the movable member and the holder. When the movable member moves with respect to the main body frame, the distance between the movable member and the holder is changed, and the pressing force of the driven roller against the drive roller is adjusted. To drive the movable member, use a cam provided between the main body frame and the movable member,
This cam may be driven by a stepping motor. Further, the holder, the movable member, and the cam are assembled on a subframe separate from the main body frame, and the subframe is swingably supported on the main body frame. It may be configured to contact or separate.

[0008]

FIG. 1 shows a paper transport mechanism of a printing apparatus 1 having a main body frame 2 and a paper transport surface 4 fixed to the frame 2 to form a straight paper transport path 3. A sheet transport table 5, a platen 6, a print head 7, a first sheet transport roller pair 8, a second sheet transport roller pair 9, and a skew correction stopper 10. In FIG. 1, reference numeral M1 denotes a motor, and reference numerals G1 to G1.
G9 is a power transmission gear, and constitutes a gear link of the motor M1. However, the reference numeral indicates the axis, and detailed description of the driving gear, the driven gear, and the like is omitted. The gear G2 is an idle gear. Reference numeral T is a tractor for continuous paper, and reference numeral F is a flapper for switching the paper transport path 3 between a cut paper mode and a continuous paper mode. In the figure, the cut paper is used. Reference numeral C denotes a control unit provided in the printing apparatus 1, which drives each unit in the printing apparatus and its timing, and processes a print signal and print data sent from a parent device such as a personal computer.

The main body frame 2 is a substrate on which a mechanism as the printing apparatus 1 is assembled, and is formed firmly by pressing a steel plate. The paper transport table 5 (FIG. 2) is also
The sheet conveying surface 4 is formed of a pressed steel plate and has a substantially flat upper surface. The hole 11a for the platen 6, the holes 11b and 11c for the first and second sheet conveying roller pairs 8 and 9, and the skew. A hole 11d for the correction stopper 10 is provided. Reference numeral 11e denotes holes for projecting the sensors S1 to S4 for detecting the paper position, and there are four holes in FIG. The sensors S1 to S4 are rotated below the sheet conveying surface 4 at the leading edge of the sheet, and return to the original position when the sheet passes. The sensor S1 detects the leading edge of the sheet, and the sensors S2 and S4 detect the trailing edge of the sheet. The sensors S2 and S3 detect the degree of skew of the sheet.

The platen 6 is supported by the lower portion of the sheet transport surface 4 and is driven by a gear link of a motor M1. The upper portion of the peripheral surface is located at substantially the same position as the sheet conveying surface 4 and is exposed from the hole 11a of the sheet conveying table 5. The print head 7 is arranged above the platen 6 so as to face the platen 6, and a gap between the print head 7 and the peripheral surface of the platen 6 forms a print gap. The first paper transport roller pair 8 is disposed upstream of the platen 6 in the paper transport direction, and the second paper transport roller 9 is disposed downstream of the platen 6 in the paper transport direction.
Has a driving roller 12 and a driven roller 13, and the second
The paper transport roller pair 9 includes a driving roller 14 and a driven roller 15. Both drive rollers 12 and 14 are pivotally supported at the lower part of the sheet conveying surface 4 and are exposed to the sheet conveying surface 4 from the holes 11b and 11c, respectively, and are driven by the gear link of the motor M1.

The driven roller 13 of the first sheet transport roller pair 8 is supported by a holder 16 as shown in FIGS. The holder 16 is a molded product of a synthetic resin,
A horizontal portion 17 that supports the driven roller 13 and a vertical portion 19 whose upper end is pressed by a coil spring 18 (biasing member) are integrally formed. In this embodiment, there are six first sheet transport roller pairs 8, and each driven roller 13 is individually supported by a holder 16. 6 holders 1
Reference numeral 6 denotes a corner portion where the vertical portion 19 and the horizontal portion 17 are individually connected to each other and is pivotally supported by the sub-frame 20. The driven roller 13 is rotatable up and down with respect to the sheet transport surface 4. The coil spring 18 is arranged between the movable member 21 and the upper part of the vertical part 19. The movable member 21 is located on the inner surface side of the rear wall of the sub-frame 20, and the lower portions at the left and right ends are swingably supported by the sub-frame 20.

The movable member 21 (FIG. 4) is a left and right long plate-like member formed by pressing a steel plate, and a swash plate-like cam follower 22 is integrally formed at one end. Further, the coil spring 1 is provided on the upper side corresponding to each of the holders 16.
8 are attached in a row, and the lower side has a claw receiving hole 2
3 are formed on the left and right. The sub-frame 20 is for integrally assembling the holder 16 with the movable member 21 and the coil spring 18 so as to be able to swing as a whole with respect to the main body frame 2. A claw 24 is provided to be inserted into 23, and has engaging projections 25 on the left and right of the upper part. The sub-frame 20 is rotatable about the upper portion of the engaging protrusion 25 by engaging the left and right engaging protrusions 25 with the protrusions 26 provided on the main body frame 2. Reference numeral 27 denotes a return spring for returning the sub-frame 20 to its original position.

A stepping motor 28 is mounted on the sub-frame 20 at one end on the inner side where the cam follower 22 of the movable member 21 is formed by screws. A disk having a pin 28 a fixed thereto at an eccentric position is attached to the output shaft, and the pin 28 a contacts the cam follower 22 of the movable member 21. That is, the cam follower 22
And the pin 28a constitute a cam mechanism provided between the main body frame 2 and the movable member 21, and this cam mechanism is driven by the stepping motor 28. The printing apparatus 1 includes a control unit C, a selection button for selecting the type of paper, and pressing force data corresponding to the type of paper in the control unit C, and the stepping motor 28 rotates a predetermined angle in accordance with the selected paper. Then, the movable member 21 is rotated with respect to the main body frame 2.

The driven roller 15 of the second sheet transport roller pair 9 can be adjusted in two steps with respect to the drive roller 14, and is constantly pressed with a substantially constant pressing force. The pressing force is generated by a biasing member such as a spring disposed at a support portion between the main body frame 2 and the driven roller 15. The skew correction stopper 10 (FIG. 5) includes a board 29, a rack 30, a pinion 32 integrated with a blocking piece 31, and a solenoid 33. The substrate 29 is long in the left and right directions, and rotatably supports six pinions 32 corresponding to the position of the holder 16. The rotation surface of the pinion 32 is parallel to the vertical surface of the substrate 29. The rack 30 can be moved in the left-right direction with respect to the substrate 29, and rack teeth are formed at six positions corresponding to the six pinions. A solenoid 33 is attached to the substrate 29 and has its armature 34 connected to one end of the rack 30. A coil spring 35 is disposed between one end of the rack 30 and the solenoid 33.
The solenoid 33 is a single-acting type that draws in the armature and maintains its position when energized, and the energization timing is under the control of the control unit C.

Therefore, the skew correction stopper 10
In the normal state in which the solenoid 33 is not energized, the rack 30 is moved to the left (a side) by the coil spring 35, and the blocking pieces 31 stand up at once.
5, the armature 34 is retracted and the rack 3
0 moves to the right (b direction) with respect to the substrate 29, and the blocking piece 3
1 is in a state of falling down all at once. When the blocking piece 31 stands up, the upper portion protrudes from the hole 11 d provided in the sheet conveying table 5 toward the sheet conveying surface 4.

At the time of printing, a sheet is set, and the type or thickness of the selected sheet is taught to the control unit C from a selection button. The control unit C reads data corresponding to the selected sheet from the storage unit, and drives the stepping motor 28 by a required angle. As a result, the pin 28a rotates and rotates while pressing the cam follower 22 of the movable member 21, thereby changing the angle of the movable member 21 with respect to the main body frame 2. This changes the degree of compression of the coil spring 18 disposed between the holder 16 and the driven roller 13 attached to the horizontal portion 17 of the holder 16.
Can be adjusted to a size suitable for the selected paper. Data for driving the stepping motor 28 by a necessary angle is obtained in advance by performing experiments on the degree of resistance (tension) to the feeding of various types of paper, the coefficient of friction, and the like.

When the power of the printing apparatus 1 is turned on, the paper transport mechanism is in an operating state. The solenoid 33 of the skew correction stopper 10 is excited by energization, the armature 34 is retracted, and the blocking piece 31 is retracted from the sheet conveying surface 4. The paper is fed by a paper feeder or a manual feeder. When the sensor S1 detects the leading end, the first and second paper transport roller pairs 8 and 9 rotate to pinch the paper. Thereafter, the paper transport mechanism of the printing apparatus 1 Automatically feeds paper. The leading edge of the sheet fed toward the print gap by the first sheet conveying roller pair 8 passes through the sensors S2 and S3. At this time, there is a time difference between the passing signal from the sensor S2 and the passing signal from the sensor S3, and when the time difference is equal to or more than the set value, the control unit C determines that "the paper is tilted" and performs skew correction. That is, the excitation of the solenoid 33 is released, the armature 34 is set free, and the rack 3 is moved by the coil spring 35.
Extrude 0. Then, the skew correction stopper 10
Protrudes from the sheet transport path.

The leading side of the paper first collides with the blocking piece 31 of the skew correction stopper 10 because the leading edge is inclined. However, the six first paper transport roller pairs 8 arranged side by side collide with the paper more as the paper transport roller pairs 8 on the side where the collision is prevented from moving (the preceding side) rotate. Subsequently, the inclination (skew) of the sheet is corrected. At this time, the pressing force of the driven roller 13 against the driving roller 12 in the first sheet conveying roller pair 8 is appropriately selected by swinging the movable member 21, so that the sheet conveying roller pair 8 There is no inconvenience such as bending the paper even if a force for feeding the paper while sliding is applied. The operation of skew correction is controlled by a timer,
After a lapse of time sufficient for skew correction after the leading edge of the sheet has passed through the sensor S3, the process ends after one second in the embodiment.
At the end of the skew correction operation, the solenoid 33 is energized, draws in the armature 34, and retracts the blocking piece 31 of the skew correction stopper 10 from the sheet conveying surface 4. Thereafter, the sheet advances to the print gap, is printed, is sent out to the second sheet conveying roller pair 9 and is discharged. When the sensor S4 detects the trailing edge of the sheet, feeding of the next sheet is started.

When the time difference between the sheet passing signals from the sensors S2 and S3 is equal to or smaller than the set value, the control unit C determines that "the sheet is not tilted", the excitation of the solenoid 33 is maintained, and the skew correction stopper is maintained. 10 blocking pieces 31
Does not protrude to the sheet transport surface 4, and the sheet advances to the print gap and is printed without skew correction.
When a paper jam occurs near the first pair of paper transport rollers 8, the sub-frame 20 is manually rotated about the upper protrusion 26, and the six driven rollers 1 are rotated.
By rotating the members 3 and 15 all at once, it is possible to widen the space where the sheet exists. This makes it possible to easily remove the jammed sheet.

As described above, the driven roller 1
Although the description has been given of the configuration in which the holder 16 and the movable member 21 that support the shafts 3 and 15 are attached to the sub-frame 20, the sub-frame is not essential, and the holder 16 and the movable member 21 are directly attached to the main body frame 2. It can also be attached to The rotation of the movable member 21 for adjusting the pressing force of the driven rollers 13 and 15 can be performed not by the stepping motor 28 but by a normal motor or a servo motor. In addition, it can also be performed manually depending on the scale. Further, the movement of the movable member may be not a rotation but another movement such as a parallel movement. The driven rollers 13, 15 are connected to the driving rollers 12, 1
The coil spring 18 pressed against the coil 4 may be another type of spring or other urging means.

[0021]

According to the first aspect of the present invention, the force for nipping the paper between the pair of transport rollers can be adjusted according to the type of the paper. The skew correction operation and the feeding operation to the print gap do not end abnormally due to an excessive sheet feeding force or an excessively small sheet feeding force. Claim 2
According to the configuration described in the above, since the paper transport roller pair includes a drive roller and a driven roller, the clamping force of the paper transport roller pair is reduced by adding a pressing force adjustment mechanism to the driven roller side to which power is not transmitted. Easy to adjust. Further, since a plurality of pairs of sheet transport rollers are provided in the sheet width direction, a slip of the rollers with respect to the sheet and a moment for rotating the sheet can be effectively given at the time of skew correction, and the skew can be quickly corrected.

According to the configuration of the third aspect, the driven roller is pivotally supported by the holder, and the holder is swingably supported on the main body frame 2 via the urging member. The pressing force adjusting mechanism may be brought into contact with another part of the holder which is not related, and the pressing force of the driven roller against the driving roller can be easily adjusted. According to the configuration of the fourth aspect, the movable member is moved with respect to the main body frame to adjust the pressing force of the driven roller to the driving roller. A mechanism for simultaneously adjusting the pressing force can be provided. According to the configuration described in claim 5, since the movable member is driven by the cam mechanism, it is easy to move the movable member with respect to the main body frame by a motor or the like. In addition, the degree of movement can be performed steplessly.

According to the configuration of the sixth aspect, the holder, the movable member and the cam mechanism are formed in the sub-frame, and the sub-frame is swingably supported by the main body frame. Can be separated from the drive roller at the same time, and a large space for processing can be provided when necessary such as paper jam.
According to the configuration described in claim 7, the rotational position of the cam mechanism by the stepping motor is reliable and accurate, so that the pressing force by the driven roller can be accurately adjusted.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a paper transport mechanism.

FIG. 2 is a perspective view of a paper transport table.

FIG. 3 is a side view (partial cross section) showing a first sheet transport roller pair.

FIG. 4 is an exploded perspective view showing a first sheet conveying roller pair.

FIG. 5 is a rear view schematically showing a skew correction stopper.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 printing device 2 main body frame 3 paper transport path 4 paper transport surface 5 paper transport platform 6 platen 7 print head 8 first paper transport roller pair 9 second paper transport roller pair 10 skew correction stoppers 11 a to 11 e holes 12 drive Roller 13 Follower roller 14 Drive roller 15 Follower roller 16 Holder 17 Horizontal part 18 Coil spring 19 Vertical part 20 Subframe 21 Movable member 22 Cam follower 23 Claw receiving part 24 Claw 25 Engagement projection 26 Projection 27 Spring for return 28 Stepping motor 28a Pin 29 board 30 rack 31 blocking piece 32 pinion 33 solenoid 34 armature 35 coil spring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Sakai 6-11-12 Honcho, Tanashi-shi, Tokyo Citizen Watch Co., Ltd. Tanashi Factory (72) Inventor Katsuhiko Sato 6-1-1, Honcho, Tanashi-shi, Tokyo No. F-term at Citizen Watch Co., Ltd. Tanashi Works (reference) 3F049 AA02 DA12 DA19 DB04 EA28 EA29 LA01 LB03 3F102 AA01 AB01 BA02 DA07 FA02

Claims (7)

[Claims] 1. A paper transport table 5 having a main body frame 2, a paper transport surface 4 fixed to the frame 2 to form a straight paper transport path 3, and a paper transport from the paper transport surface 4 to the paper transport platform 5. Platen 6 exposed to road 3
A print head 7 provided opposite the platen 6;
A pair of paper transport rollers 8 provided upstream of the platen 6 in the paper transport direction and nipping and transporting the paper from the front and back.
And a skew correction stopper 1 which is provided between the platen 6 and the pair of transport rollers 8 in the transport direction, advances to the paper transport path 3, and is retractable from the paper transport path 3.
0, wherein the force for nipping the sheet by the pair of transport rollers 8 can be adjusted according to the type of sheet. 2. The printing apparatus according to claim 1, wherein the sheet transport roller pair 8 includes a drive roller 12 and a driven roller 13, and a plurality of pairs are provided in a sheet width direction. 3. The driving roller 12 is connected to the sheet transport table 5.
The driven roller 13 is supported by the main body frame 2.
The holder 16 is rotatably supported by a holder 16 that is swingably supported by the main body frame 2 and the holder 1.
6 and the driven roller 13
The printing apparatus according to claim 2, wherein the printing apparatus is swung in a direction in which the printing apparatus is pressed against the driving roller 12. 4. The biasing member is provided between a holder and a spring receiving portion formed on a movable member supported by the main body frame, and the movable member is positioned relative to the main body frame. 4. The printing apparatus according to claim 3, wherein the movement changes a distance between the spring receiving portion and the holder 16, and adjusts a pressing force of the driven roller 13 against the driving roller 12. 5. 5. The printing according to claim 4, wherein the movable member is moved with respect to the main frame by being driven by a cam mechanism provided between the main frame and the movable member. apparatus. 6. The sub-frame 2 in which the holder 16, the movable member 21, and the cam mechanism are formed separately from the main body frame 2 and are swingably supported by the main body frame 2.
6. The printing apparatus according to claim 5, wherein the driven roller is provided so as to come into contact with or separate from the driving roller by the swinging motion of the sub-frame. 7. The cam mechanism according to claim 5, wherein the cam mechanism is driven by a stepping motor.
3. The printing device according to claim 1.