JP4067693B2 - Printing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus including a skew correction mechanism that corrects an inclination of a sheet that is fed with an inclination with respect to a correct feeding direction.
[0002]
[Prior art]
In the paper transport mechanism of the printer, a skew correction mechanism is provided upstream of the platen in the paper transport direction, and the leading edge of the paper collides with the partition piece of this mechanism to correct the skew (skew) of the paper with respect to the transport direction. Often to do. The screen piece advances to the paper transport surface only during skew correction and blocks the paper transport path. In other cases, the screen strip is retracted from the paper transport surface so as not to interfere with the paper transport.
[0003]
However, in the conventional skew correction mechanism (for example, utility model registration No. 2508855), the paper is collided with the screen piece to correct the skew, and then the screen piece is retracted while the paper is still colliding. The retraction of the partition piece becomes incomplete, which may hinder the conveyance of the paper after skew correction. This is because the paper colliding with the screen piece is strongly pressed by the feeding force of the paper transport roller pair for feeding even in this state, and the friction between the front end of the paper and the collision piece is large, and the screen piece is transported. This is because there is a twist between the movable parts of the mechanism that is pushed in the direction to retract the partition piece. Such troubles are likely to occur particularly when using so-called stiff paper or thick paper.
For this reason, in the conventional mechanism, a large driving force is required to retract the partition piece, or the leading edge of the sheet may be damaged as a result of forcibly retracting.
[0004]
[Problems to be solved by the invention]
It is an object of the present invention to provide a printing apparatus that can lightly retract a partition piece in a skew correction mechanism and that does not damage the leading edge of a sheet.
[0005]
[Means for Solving the Problems]
The printing apparatus includes a control device including a paper conveyance table, a platen, a print head, a paper conveyance roller pair, a skew correction mechanism, and a paper position detection sensor. The paper transport table forms a straight paper transport path on the paper transport surface. The platen is disposed 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 disposed so as to face the platen. The pair of paper transport rollers is to feed the paper while sandwiching the pair of rollers, and is composed of a driving roller and a driven roller pressed against the driving roller, and a plurality of pairs are provided in the paper width direction. The skew correction mechanism is provided between the platen and the pair of transport rollers in the transport direction of the paper, and causes the partition piece to advance into the paper transport path by a command from a control device based on a signal from a paper position detection sensor such as a paper-in sensor. Also evacuate.
[0006]
The control device controls the next operation. The sheet is fed by driving the pair of conveying rollers in the forward direction, and the leading edge of the sheet is caused to collide with a partition piece of the skew correction mechanism to correct the skew (skew) of the sheet with respect to the conveying path. Then, after a set time sufficient for skew correction, the pair of transport rollers is rotated in a direction opposite to the sheet transport direction by a set amount, and the leading edge of the sheet is pulled away from the screen piece. Then, the partition piece is retracted from the conveyance path, and thereafter, the pair of sheet conveyance rollers is driven in the forward direction to feed the sheet toward the print gap between the platen and the print head.
In some cases, a plurality of partitioning pieces of the skew correction mechanism are arranged in a direction crossing the paper conveyance path, and these are advanced to the paper conveyance surface all at once using a drive plate and retracted.
The drive plate may be driven by a linear drive solenoid.
In some cases, the skew correction mechanism screen, the drive plate, and the linear drive solenoid are assembled into a sub-frame to assemble the skew correction mechanism into one unit.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a paper transport mechanism of the printing apparatus 1, which includes a main body frame 2, a paper transport table 5, a platen 6, a print head 7, a first paper transport roller pair 8, and a second paper transport roller pair 9. , And a skew correction mechanism 10. The paper transport table 5 includes a paper transport surface 4 that is fixed to the main body frame 2 and forms a straight paper transport path 3. In FIG. 1, reference numeral M1 denotes a motor, and reference numerals G1 to G9 denote power transmission gears, which constitute a gear link of the motor M1. However, the code | symbol has shown the shaft center, and detailed description, such as a drive side gear and a driven side gear, is abbreviate | 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, cut sheets are used. Reference numeral C denotes a control unit provided in the printing apparatus 1 that drives each part of the printing apparatus and the timing thereof, and processes a print signal and print data sent from a parent device such as a so-called personal computer.
[0008]
The main body frame 2 serves as a substrate on which the 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 a pressed product of a steel plate and has a top surface that is a substantially flat paper transport surface 4. A hole 11a for the platen 6 is provided with the first and second paper transport roller pairs 8,9. Holes 11b and 11c, and a hole 11d for the skew correction mechanism 10 are provided. Reference numeral 11e is a hole for projecting the paper position detection sensors S1 to S4, and there are four holes in FIG. The sensors S1 to S4 (FIG. 3) are rotatably attached to the lower side of the paper transport table 5 by a horizontal shaft 12 in a direction crossing the transport path 3, and the engaging claws 13 are moved to the left and right with the horizontal shaft 12 in between. And a balancer 14 for maintaining this in the advanced position, and a trigger 15 integrally therewith. Reference numeral 16 denotes a photocoupler, and reference numeral P denotes paper.
[0009]
Sensors S1 and S4 rotate opposite to the conveying direction while causing slippage between the cut paper and the back of the paper (FIGS. 1 and 2), and sensors S2 and S3 are pressed when the leading edge of the paper hits. Rotate in the transport direction (Fig. C, D). That is, the sensors S1 to S4 have the same structure, but are attached in reverse directions between the groups. In either case, when the paper passes by the balancer 14, it returns to the original position. Sensor S1 detects the leading edge of the paper, and sensors S2 and S4 detect the trailing edge of the paper. The sensor S2 and the sensor S3 are slightly displaced in the front-rear direction in the paper conveyance direction, and detect the degree of inclination (skew) of the paper.
[0010]
The platen 6 is pivotally supported at the lower part of the sheet conveying surface 4 and is driven by a gear link of the motor M1. The upper part of the peripheral surface is exposed to the hole 11a of the paper transport table 5 at substantially the same position as the paper transport surface 4. The print head 7 is arranged on the upper part of the platen 6 so as to oppose the platen 6, and a print gap is formed between the print head 7 and the peripheral surface of the platen 6.
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 pair 9 is disposed downstream of the platen 6, and the first paper transport roller pair 8. Includes a driving roller 17 and a driven roller 18, and the second sheet conveying roller pair 9 includes a driving roller 19 and a driven roller 20. Both drive rollers 17 and 19 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 a gear link of the motor M1.
[0011]
The driven roller 18 of the first pair of paper transport rollers 8 is pivotally supported by the holder 21 as shown in FIGS. 1 and 4, and is driven by pressing the upper end of the holder 21 with a coil spring 22 (biasing member). The roller 18 is pressed against the driving roller 19. In this embodiment, there are six first paper conveying roller pairs 8, and each driven roller 18 is individually supported by a holder 21.
The driven roller 20 of the second pair of paper transport rollers 9 can be adjusted in two steps with respect to the driving roller 19 and is always pressed with a substantially constant pressure contact force. The pressure contact force is generated by a biasing member such as a spring disposed on the support portion of the main body frame 2 and the driven roller 20.
[0012]
The skew correction mechanism 10 (FIGS. 5 and 6) includes a sub frame 23, a drive plate 24, a partition piece 25, and a solenoid 26. The sub frame 23 is for assembling the drive plate 24, the partition piece 25, and the solenoid 26 as a whole, and the skew correction mechanism 10 is attached to the printing apparatus 1 by attaching the sub frame 23 to the main body frame 2. can do. The sub-frame 23 is a press-formed product having an L-shaped cross section that is long in the direction crossing the sheet conveying surface 4 and is integrally formed with a vertical piece 27 and a horizontal piece 28. The vertical piece 27 includes six shaft support portions 29 of the partition piece 25 and arcuate guide cutouts 30 formed on both sides thereof, and six sets of these are arranged as a set, and the lower portion is cut at intervals in the longitudinal direction. The guide piece 31 (FIG. 6) by raising is provided. The guide piece 31 is spaced from the vertical piece 27. The shaft support portion is formed by burring at the time of pressing, and provides a rotation shaft that is parallel to the paper transport direction with respect to the rotation of the partition piece 25.
[0013]
The drive plate 24 is positioned below the front surface of the vertical piece 27 (the front side in the sheet conveyance direction), and is guided by the guide piece 31 so as to be slidable in the longitudinal direction of the vertical piece 27. One end of the drive plate 24 is bent at a substantially right angle to the rear side to form an attachment portion 33 that is coupled to the armature 32 of the solenoid 26. The drive plate 24 is also a member corresponding to the rack of the pinion rack mechanism, and the gear teeth (rack teeth) 34 having a partially linear arrangement on the upper side are made to correspond to the shaft support portion 29 of the partitioning piece 25, and the interval is set. It is formed in 6 places.
[0014]
In this embodiment, the partition piece 25 has a rectangular shape, and one end portion of the rectangle extends from the hole 11d (FIGS. 2 and 5) to the sheet conveying path surface 4 and is an exposed portion that retreats, and the other end. The part has a structure corresponding to the pinion of the pinion rack mechanism. In a portion corresponding to the pinion, a shaft support hole 35 and a gear tooth (pinion tooth) 36 extending about 90 ° around the shaft support hole 35 are formed. Further, the partition piece 25 is provided with a shape in which guide claws 37 can wrap around the rear side of the vertical piece 23 (rear side in the sheet conveying direction) through the guide notch 30 at locations corresponding to both sides of the shaft support hole 35. ing.
[0015]
The drive plate 24 is engaged with the guide piece 31 and slidably attached to the front surface of the vertical piece 27 of the subframe 23. Next, the shaft support hole 29 is fitted into the shaft support portion 29 of the vertical piece 27 to attach the partition piece 25, and the guide claws 37 on both sides are engaged with the guide notches 30 of the vertical piece 27. As a result, the partition piece 25 is attached to the vertical piece 27 so as not to fall off even if the shaft support portion 29 is not provided with a special retaining member. At the same time, the pinion teeth 36 provided at the other end of the partition piece 25 mesh with the rack teeth 34 of the drive plate 24.
[0016]
The solenoid 26 is fixed to one end side of the horizontal piece 28 of the subframe 23, and the tip of the armature 32 is coupled to the mounting portion 33 of the drive plate 24. The solenoid 26 is a single-acting type, which pulls the armature 32 when energized and returns to its original position with the spring 38 when energized. That is, when energized, the drive plate 26 is moved to the right in FIG. 6, and the plurality of partitioning pieces 25 are simultaneously rotated to the left (a to b), and are retracted from the sheet conveying path surface 4. When the energization is cut off, the screen pieces 25 simultaneously rotate right (from b to a) and advance from the hole 11d to the sheet conveyance path surface 4.
As shown in FIG. 6, the six drive rollers 17 are attached to one drive shaft 39, and the drive shaft 39 is driven by the motor M1 by the gear link, but the motor M1 and the solenoid 26 are controlled. Under the control of the device C, the system program stored in the storage unit of the control device C associates the forward / reverse rotation of the motor M1 with the energization timing of the solenoid.
[0017]
When the printing apparatus 1 is operated and a print signal is input from a parent device such as a personal computer, the paper transport roller pair 8 rotates forward and feeds the paper P. The solenoid 26 is energized, and the partitioning piece 25 is in a position where the sheet conveying path 4 is retracted. When the leading edge of the paper P passes the sensor S1 (paper-in sensor), the sensor S1 rotates counterclockwise and transmits an ON signal to the control device C. In response to this ON signal, the control device C cuts off the energization of the solenoid 26 and advances the partitioning piece 25 to the conveyance path surface 4. The pair of paper transport rollers 8 continues to rotate forward. The sheet P moves in the transport direction, the leading edge of the sheet rotates the sensors S2 and S3, and an ON signal from the sensors S2 and S3 is transmitted to the control device C. There is a set time difference in the transmission of the ON signal from the sensors S2 and S3, and the inclination of the leading edge of the sheet is detected by comparison with the time difference. That is, if the time difference is larger or smaller than the set time difference, it is determined that the sheet is inclined, and the leading edge of the sheet is made to collide with the partitioning piece 25 with the state of the partitioning piece 25 advancing on the sheet conveying surface 4 as it is. Correct the skew of the paper. In the skew correction, since the sheet is inclined with respect to the transport direction, only one side continuously feeds the sheet colliding with the partition piece 25, and on one side, between the sheet P and the pair of sheet transport rollers 8. Is caused to slip, and on the other side, the paper is continuously fed to correct the inclination of the paper.
[0018]
When it is determined that the sheet is inclined, the control device C activates the timer, and after a predetermined time, determines that the skew correction is completed and proceeds to the next step. The predetermined time is a time from when it is determined that there is an inclination until the skew of the sheet is actually corrected, and is set by actual measurement. This time differs depending on the type and thickness of the paper, but is about 1 second. When the skew correction is completed, the control device C reverses the motor M1 to reversely rotate the paper transport roller pair 8 and pulls the paper P from the screen piece 25 while energizing the solenoid 26 during that time. Retreat from the transfer surface 4. The time for rotating the sheet conveying roller pair 8 in the reverse direction is very short and less than one rotation of the driving roller 17. When energization of the solenoid 26 is confirmed, the control device C rotates the pair of paper transport rollers 8 forward to feed the paper P toward the print gap.
[0019]
When it is determined that the time difference is within the set range at the positions of the sensors S2 and S3 and the sheet is not inclined, the control device C keeps energization of the solenoid 26, and the sheet conveying roller pair 8 also maintains the normal rotation. The paper P is fed directly into the print gap without performing skew correction.
Then, printing is performed in the print gap as in the conventional case, and line feed is performed by the second paper transport roller 9. When there is a print end signal or a page change signal, the control device C sends out the paper P by the second paper conveyance roller pair 9, and when the paper P passes the sensor S4, the control device causes the paper conveyance roller 9 to respond to the signal from the sensor S4. , And the printing operation for one sheet P is finished.
[0020]
As described above, the number of the partitioning pieces 25 is six as an embodiment. However, the partitioning pieces 25 only need to be arranged in the direction crossing the sheet conveying surface 4 so as to be able to advance and retreat. There are also things. Further, the drive source for moving the partition piece 25 forward and backward to the sheet conveying surface is not limited to the solenoid 26, and a structure that converts the rotation of the motor into a linear motion using a cam or the like may be used.
The forward / reverse rotation of the paper transport roller pair 8 can also be performed by switching the idle gear in the gear link.
In the above description, the skew correction mechanism is configured as a unit using the sub-frame 23. However, the vertical piece 27 is cut out from the main body frame 2, and the screen piece 25, the drive plate 24, and the solenoid 26 are directly connected to the main body frame 2. May be attached to.
[0021]
【The invention's effect】
According to the configuration of the first aspect, when the skew correction is completed, the paper transport roller pair reverses before the screen strip is retracted from the paper transport path, and the paper is pulled away from the screen strip 31. Does not require great force to evacuate. In addition, the leading edge of the paper is not pulled and damaged by the retreating movement of the partitioning piece, and the paper jam does not occur.
According to the configuration of the second aspect, the skew correction mechanism can be operated only when cut paper with a possibility of skew correction is fed by the signal of the paper-in sensor, and unexpectedly in the case of continuous paper. It is possible to prevent an accident in which the partition piece advances to the sheet conveying surface and obstructs the printing operation.
According to the third aspect of the present invention, the partition piece that rotates about the rotation axis parallel to the sheet conveying direction may be a flat plate, and the structure of the partition piece can be made extremely simple.
[0022]
According to the configuration described in claim 4, by using the drive plate, the partition piece can be easily rotated by the linear drive solenoid, and the structure is simple and the failure is not easily caused. Is reliable.
According to the configuration described in claim 5, since the engagement between the partitioning piece and the drive plate is the same as that of the pinion and the rack mechanism, the linear motion of the drive plate is smoothly and reliably converted into the rotational motion of the partition. Is done.
According to the configuration of the sixth aspect, since the entire skew correction mechanism is provided as one unit, it is possible to improve the work efficiency by distributing the assembly of the printing apparatus.
According to the configuration of the seventh aspect, by arranging a plurality of partitioning pieces in a direction crossing the sheet conveyance path, the same skew correction mechanism can be made to correspond to sheets having different widths, and is in contact with the leading edge of the sheet. Since the screen pieces are dispersed in the width direction, it is easy to correct skew correctly.
[Brief description of the drawings]
FIG. 1 is a side view showing an outline of a paper transport mechanism. FIG. 2 is a perspective view of a paper transport table. FIG. 3 is a side view showing the structure and operation of a sensor. FIG. 5 is a perspective view of the mechanism portion as viewed from the front side in the paper conveyance direction. FIG. 5 is a perspective view of the skew correction mechanism. FIG. 6 is a front view of the skew correction mechanism.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Printing apparatus 2 Main body frame 3 Paper conveyance path 4 Paper conveyance surface 5 Paper conveyance stand 6 Platen 7 Print head 8 1st paper conveyance roller pair 9 2nd paper conveyance roller pair 10 Skew correction mechanism 11a-11e Hole 12 Horizontal axis 13 Engaging Claw 14 Balancer 15 Trigger 16 Photo Coupler 17 Drive Roller 18 Driven Roller 19 Driven Roller 20 Driven Roller 21 Holder 22 Coil Spring 23 Subframe Claw Receiving Part 24 Drive Plate 25 Screening Piece 26 Solenoid 27 Vertical Piece 28 Horizontal Piece 29 Axis Support Part 30 Guide notch 31 Guide piece 32 Armature 33 Mounting part 34 Gear teeth (rack teeth)
35 Shaft support hole 36 Gear teeth (pinion teeth)
37 Guide claw 38 Spring 39 Drive shaft

Claims (7)

A sheet conveying table 5 having a sheet conveying surface 4 that forms a straight sheet conveying path 3, a platen 6 that is exposed from the sheet conveying surface 4 of the sheet conveying table 5 to the sheet conveying path 3, and a platen 6 A print head 7 provided opposite to the platen 6, a paper conveyance roller pair 8 provided on the upstream side of the platen 6 in the paper conveyance direction to nipping and conveying the paper from the front and back, and the platen 6 and the conveyance in the conveyance direction. A control device including a skew correction mechanism 10 having a partition piece 25 which is provided between the roller pair 8 and advances into the paper transport path 3 and can be retracted from the paper transport path 3 and a paper position detection sensor; The pair of paper transport rollers 8 rotates in a direction opposite to the paper transport direction by a set amount in a direction in which the paper is pulled away from the screen strip 25 before the screen strip 25 of the skew correction mechanism 10 is retracted from the paper transport path. Preparative printing apparatus characterized. The partition piece 25 of the skew correction mechanism 10 advances onto the paper transport path in synchronization with a paper detection signal from a paper-in sensor arranged in the paper transport path 3 upstream of the paper transport roller pair 8. The printing apparatus according to 1. The partition piece (25) of the skew correction mechanism (10) is advanced or retracted into the paper conveyance path by rotating around a rotation axis provided below the paper conveyance table (5) and parallel to the paper conveyance direction. The printing apparatus according to 1 or 2. The partition piece 25 is engaged with a drive plate 24 that linearly moves in a direction transverse to the sheet conveyance path 3 below the sheet conveyance table 5, and is rotated by the linear movement of the drive plate 24. The printing device described in 1. The engagement between the partition piece 25 and the drive plate 24 is meshing between the gear teeth 36 of the partition piece 25 corresponding to the pinion and the pinion of the rack mechanism and the gear teeth 34 of the drive plate 24 corresponding to the rack. The printing apparatus according to claim 4. The skew correction mechanism 10 includes a sub-frame 23 and a linear drive solenoid 26 fixed to the sub-frame 23, and a partition piece 25 is rotatably supported on the sub-frame 23 and a drive plate 24 is slidably attached to the sub-frame 23. 6. The printing apparatus according to claim 4, wherein the armature 32 of the solenoid 26 is connected to the plate 24 so as to form a unit as a whole. The printing apparatus according to claim 1, wherein a plurality of partitioning pieces 25 of the skew correction mechanism 10 are arranged in a direction crossing the sheet conveying path 3.

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