JP4853556B2 - Roll paper transport device and printing device - Google Patents

Description

The present invention relates to a roll paper transport device for smoothly transporting roll paper and a printing apparatus including the roll paper transport device.

Conventionally, in a printing apparatus in which roll paper is not held by a shaft but is set in a thrown state, a buffer roll is provided so that the tension of the roll paper becomes a certain value or less. The buffer roll is elastically held, and controls the magnitude of tension applied to the roll paper by bending the roll paper (for example, Patent Document 1).

In addition, a configuration including a buffer plate is also known in order to absorb a strong tension generated by the inertia of the roll unit when, for example, the conveyance of the roll paper in a conveyance stop state is started. further,
A photo sensor is provided to detect the presence or absence of roll paper. The photo sensor is provided in the vicinity of the roll paper in the conveyance path. In some cases, the photosensor may be covered with a metal buffer plate. With such a configuration, static electricity generated by friction or the like when the roll paper or the like is conveyed is released by being conducted to the buffer plate, and the photosensor is prevented from being destroyed (for example, Patent Document 2).

On the other hand, a configuration is known in which a mechanical switch is installed as a paper detection unit in place of a photosensor so as not to be affected by static electricity. FIG. 7 is a cross-sectional view showing a paper detection unit and a buffer mechanism unit in a conventional thermal printing apparatus. As shown in FIG. 7, the printing apparatus 30 includes a roll unit 32 around which roll paper 31 is wound. The roll paper 31 is sandwiched between a print head 33 and a platen 34, and the platen 34 is rotated to rotate the roll paper. 31 is conveyed. The switch lever 38 detects the presence or absence of the roll paper 31. A buffer plate 36 of the buffer mechanism 35 and a switch lever 38 of the paper detector 37 are provided in the transport path between the roll unit 32 and the platen 34 along the transport direction of the roll paper 31. The buffer plate 36 acts so as to relieve the strong tension that the roll paper 31 receives due to the inertia of the roll unit 32 at the start of conveyance by the swinging of the buffer plate 36.

The paper detection unit 37 that detects the roll paper 31 includes a switch lever 38 and a mechanical switch 39. The switch lever 38 rotates in accordance with the presence or absence of the roll paper 31, and the mechanical switch 3
9, the contact lever 40, which is a contact terminal with the switch lever 38, comes into contact and slides, and the switch is turned on. This contact portion is a contact portion 41. Switch lever 38
Is at the position P and the roll paper 31 is not at the position P, the switch lever 38 is separated from the contact lever 40 and is in the switch OFF state. When the roll paper 31 is loaded, the switch lever 38 rotates to the position Q and contacts the contact lever 40, and the switch is turned on.
The presence / absence of the roll paper 31 is detected based on the ON / OFF state of the switch.

JP-A-6-8554 JP 2000-62281 A

However, in the conventional technique, a buffer roll (Patent Document 1) having a large installation space or a buffer mechanism unit 35 and a paper detection unit 37 is provided between the roll unit 32 and the platen 34. Considering the set of roll parts 32 in a large diameter state, the distance L from the platen 34
It was necessary to set 1 long. In addition, as shown in FIG.
Is moved between the roll paper position R1 and the roll paper position R2 . As the roll paper 31 changes its position, the switch lever 38 repeats rotation though a slight distance, and the switch lever 38 and the contact lever 40 slide in the contact state (switch ON state) at the contact portion 41 inside the mechanical switch 39. Repeat the movement. For this reason, the contact portion 41 is easily worn and easily causes poor electrical conduction.

In order to solve the above-described problems, the present invention provides a roll paper transport device and a printing device that reduce the area required for installing the buffer mechanism and the paper detection unit, and reduce the electrical continuity failure of the contact part. Objective.

The roll paper transport device of the present invention is a device for transporting roll paper, and includes a paper detection unit that detects the presence or absence of roll paper, and the paper detection unit detects the roll paper in order to detect the roll paper. A detection lever that rotates when contacted with paper, a cam that is formed integrally with the detection lever and has an arc surface concentric with the rotation center of the detection lever, and a switch lever that can contact the cam. The switch lever comes into contact with an arc surface of the cam that rotates in conjunction with the detection lever when the roll paper is mounted and contacts the detection lever .

According to this roll paper transport device, the presence or absence of roll paper is detected by the paper detection unit. When the roll paper is loaded, the paper detection unit rotates when the detection lever is pushed by the roll paper. When the detection lever rotates, the cam integrated with the detection lever rotates. The cam has an arc surface concentric with the rotation center of the detection lever. The switch lever moves from the separated state to the contacted state with respect to the arc surface as the cam rotates, so that the switch lever is pushed by the arc surface and swings to operate the mechanical switch .

According to this configuration, when the roll paper is loaded, the switch lever comes into contact with the arcuate surface of the cam and rides up. At this time, the switch lever consists a contact lever while riding on the arcuate surface with the abutment slides state. When the switch lever completely rides on the arc surface, even if the arc surface rotates in conjunction with the rotation of the detection lever, the switch lever does not swing because the arc surface is concentric with the rotation center of the detection lever. That is, the switch lever and the contact lever do not slide while in contact with each other. Therefore, sliding between the switch lever and the contact lever can be suppressed to a minimum, and contact wear due to sliding and electrical conduction failure due to contact wear can be prevented.

  A printing apparatus according to the present invention is equipped with the roll paper transport device.

According to this printing apparatus, there is provided a compact roll paper transport device in which the paper detection unit and the buffer mechanism unit described above are arranged substantially integrally. Thereby, the printing apparatus can prevent an excessive tension from acting on the roll paper due to the swing of the buffer plate of the buffer mechanism. In addition, because the detection lever that detects the roll paper is configured not to protrude independently from the guide surface of the buffer plate,
Damage to the roll paper can be avoided. Furthermore, sliding between the switch lever and the contact terminal of the mechanical switch can be suppressed to the minimum, and contact wear due to sliding and electrical conduction failure due to contact wear can be prevented. By providing the roll paper transport device of the present invention, it is possible to provide a compact printing device having the above-described features.

FIG. 2 is a perspective view illustrating an appearance of a printing apparatus. Sectional drawing which shows the positional relationship of a buffer mechanism part and a paper detection part. Sectional drawing which shows the state which mounted | wore the roll paper to the printing apparatus. Sectional drawing which shows a roll paper conveyance state when tension | tensile_strength is added to roll paper. The front view which shows the paper detection part in a roll paper absence state. The front view which shows the paper detection part in a roll paper presence state. Sectional drawing which shows the positional relationship of the conventional buffer mechanism part and a paper detection part.

Hereinafter, embodiments of a roll paper transport device and a printing device according to the present invention will be described with reference to the drawings.
(Embodiment)

FIG. 1 is a perspective view illustrating an appearance of the printing apparatus. 2 is a cross-sectional view showing the positional relationship between the buffer mechanism and the paper detection unit, and FIG. 3 is a cross-sectional view showing a state in which roll paper is mounted on the printing apparatus. As shown in FIG. 1, the printing apparatus 1 includes a lower exterior 2 and an upper exterior 3. The upper exterior 3 has a lid 4 that can be freely opened and closed on the upper surface, and a roll unit 6 in which a roll paper 5 to be mounted on the upper exterior 3 is accommodated in a roll shape inside the lid 4 and a tension applied to the roll paper 5. Is stored in a buffer mechanism 7 that absorbs a change in tension so as to keep the tension below a certain value, and a storage unit 16 that is provided by cutting out a part of the buffer mechanism 7 to detect the presence or absence of roll paper. A paper detection unit 8 and a print head 9 that performs printing on the roll paper 5 are provided. Further, the lid 4 is provided with a platen 10 that, when closed, brings the roll paper 5 into contact with the print head 9 in a pressed state.

Further, a lid opening button 11 is provided on the upper surface of the upper exterior 3, and a power switch 12 is provided on the front side surface. As shown in FIG. 2, the buffer mechanism unit 7 has a buffer plate 14 that guides the roll paper 5 to the print head 9 and relaxes the tension applied to the roll paper 5, and the buffer plate 14 relaxes the tension. Therefore, with the buffer plate rotation center 15 as the center, when the tension increases, it can rotate (swing) in the direction of the print head 9, and when the tension decreases, it returns to the direction of the roll unit 6. The buffer plate 14 extends in a direction substantially perpendicular to the direction in which the buffer plate 14 rotates so that the roll paper 5 can be guided. The paper detection unit 8 includes a detection lever 17 for detecting the roll paper 5, a detection lever rotation center 18 for rotating the detection lever 17 in contact with the roll paper 5, and a mechanical switch 22 for detecting the presence or absence of the roll paper 5. The switch lever 23 transmits the rotation of the detection lever 17 to the mechanical switch 22.

In order to perform printing on the roll paper 5 by the printing apparatus 1 having such a configuration, first, the lid opening button 11 is pressed to open the lid 4, and the roll unit 6 is mounted inside the upper exterior 3. Next, the roll part 6
Pull the roll paper 5 out of the paper. As shown in FIG. 3, the drawing direction is drawn in the direction of the print head 9 so as to cover the guide surface 19 and the detection lever 17 of the buffer plate 14 that guides the roll paper 5. When the lid 4 is closed after the roll paper 5 is pulled out from the roll unit 6, the platen 10 provided on the lid 4 is brought into contact with the print head 9 via the roll paper 5. At this time, the detection lever 17 of the paper detection unit 8 is pushed by the roll paper 5 and rotates, and is pushed down from the position P when the roll paper 5 is not present to the position Q. The rotation of the detection lever 17 rotates around the detection lever rotation center 18 substantially in parallel with the extending direction of the buffer plate 14.

According to the printing apparatus 1 having such a configuration, the buffer mechanism unit 7 and the paper detection unit 8 disposed between the roll unit 6 and the platen 10 substantially accommodate the paper detection unit 8 in the storage unit 16 of the buffer mechanism unit 7. It is the composition to do. With this configuration, the installation space can be greatly reduced as compared with the case where the buffer mechanism unit 7 and the paper detection unit 8 are individually arranged as shown in FIG. Therefore, the roll part 6
The distance L2 between the platen 10 and the platen 10 can be set shorter than the distance L1 between the roll portion 32 and the platen 34 shown in FIG.

Further, the roll paper 5 loaded in the printing apparatus 1 is guided from the roll unit 6 to the guide surface 19 of the buffer plate 14.
Along the platen 10 direction. And the detection lever 17 of the paper detection part 8 arrange | positioned so that it may overlap with the guide surface 19 is pushed down, and the detection lever 17 is rotated. The mechanical switch 22 is actuated via the switch lever 23 by the rotation of the detection lever 17 and the loading of the roll paper 5 is detected. Further, the roll paper 5 extends to the print head 9 along the platen 10, and is pressed between the print head 9 and the platen 10. Next, the roll paper 5 is printed by the print head 9 while being conveyed by the rotation of the platen 10 by a paper feed motor (not shown), and is discharged out of the printing apparatus 1 after printing. At this time, the roll paper 5 can be cut and taken out by an auto cutter (not shown).

By the rotation of the platen 10, the roll paper 5 is sequentially pulled out from the roll unit 6 and supplied to the print head 9. In this case, the print head 9 is a thermal system, and the roll paper 5 is thermal paper. The roll paper 5 supplied to the print head 9 develops color in response to the heat generated by each heating element of the print head 9. By controlling this color development, the printing apparatus 1 can execute predetermined printing.

Next, conveyance of the roll paper 5 will be described. In the case of a configuration in which the roll unit 6 is thrown in and mounted as in the printing apparatus 1, when the platen 10 rotates to start supplying the roll paper 5 to the print head 9, first, the stopped roll unit 6 is rotated. Pull out the roll paper 5. When the roll paper 5 is pulled out, the roll unit 6 is resisted against the static friction and inertial force that the roll unit 6 keeps stationary.
Needs to be rotated, and a large load is applied to the motor that temporarily rotates the platen 10. In particular, when the supply speed of the roll paper 5 is set high so that printing can be performed at high speed, a larger load is applied to the motor to start the rotation of the roll unit 6. At the same time, more tension is applied to the roll paper 5 in proportion to the load on the platen 10. For this reason, each of the roll part 6 and the platen 10 is in tension, and the roll part 6 is in a state where the rotation cannot be started immediately.

Thereafter, the roll paper 5 starts to be pulled out by the rotation of the platen 10 and is supplied to the print head 9. In this case, due to the tension applied to the roll paper 5, the roll paper 5 may be stretched, wrinkled, broken, or the like causing printing defects. Furthermore, when the paper feed motor is a step motor, there may be a step-out. Further, in the case where the printing apparatus 1 is a POS printer that performs receipt printing, since the receipt printing is intermittent printing, the load on the platen 10 and the tension increase on the roll paper 5 are repeated every time printing is started. Therefore, the roll paper 5 may not be supplied smoothly to the print head 9.

In order to solve this problem, in order to smoothly supply the roll paper 5 to the printing apparatus 1,
A shock-absorbing mechanism 7 is provided to relieve the load on the platen 10 and the tension on the roll paper 5. FIG.
These are sectional drawings which show a roll paper conveyance state when tension | tensile_strength is added to roll paper. When the printing apparatus 1 starts printing from the printing pause state, a large tension is applied to the roll paper 5 by the force to rotate the platen 10. In response to the tension applied to the roll paper 5, the buffer plate 14 of the buffer mechanism unit 7 rotates about the buffer plate rotation center 15 in the direction of the platen 10. When the buffer plate 14 rotates in the direction of the platen 10, the tension applied to the roll paper 5 is relaxed, and the platen 10 can start rotating without instantaneously applying a large load when starting to rotate. FIG. 4 shows the buffer plate 1
4 shows a state in which the sheet 4 is rotated in the direction of the platen 10 as much as possible, and the normal roll paper 5 is not rotated so far.

When the roll unit 6 rotates and the roll paper 5 starts to be fed at a constant speed, the load related to the conveyance of the roll paper 5 is the friction between the roll unit 6 and the roll receiving part of the upper exterior 3 and the roll paper 5. And only the friction with the guide surface 19 of the buffer plate 14 that guides the roll paper 5, and both the frictions have a small load. The buffer plate 14 returns to a position in the direction of the roll unit 6 that is balanced with the load from a state in which the buffer plate 14 is largely rotated at the start of conveyance of the roll paper 5. It is possible to prevent an excessive tension from acting on the roll paper due to the relaxation of the tension caused by the rotation of the buffer plate 14.

Further, as shown in FIGS. 3 and 4, the distal end portion 27 of the detection lever 17 that detects the roll paper 5 has substantially the same cross-sectional shape as the guide surface 19 in a cross-sectional shape perpendicular to the transport direction of the roll paper 5. . As shown in FIG. 3, when the roll paper 5 is mounted, the roll paper 5 is not tensioned and the buffer plate 14 does not rotate. On the other hand, a part of the tip 27 is part of the platen 10 and the guide surface 1.
It is pushed and rotated by the roll paper 5 existing between 9 and the mechanical switch 22 is operated. Thereby, it is detected that the roll paper 5 is loaded.

When tension is applied to the roll paper 5 by the rotation of the platen 10 after the roll paper 5 is loaded, the buffer plate 14 rotates in the direction of the platen 10 as shown in FIG. As the buffer plate 14 rotates, the roll paper 5 with which the leading end 27 abuts moves from the roll paper position R1 to the roll paper position R2. Corresponding to the movement of the position of the roll paper 5, the leading end 27 also rotates and moves to the roll paper position R2. As the tension applied to the roll paper 5 increases and the buffer plate 14 rotates in the direction of the platen 10, the cross-sectional shape of the leading end portion 27 and the cross-sectional shape of the guide surface 19 overlap as if they are the same surface. become.

Further, the front end 27 rotates in conjunction with the buffer plate 14 in any state where the buffer plate 14 rotates in the direction of the roll unit 6 or the platen 10, and the guide surface 19 of the buffer plate 14.
Further, the leading end 27 alone does not protrude toward the roll paper 5 side. Therefore, it is possible to prevent the leading end 27 from pushing up the roll paper 5 locally and damaging the roll paper 5 such as streaks and dents. Further, as the roll paper 5 is applied with a large tension, the leading end portion 27 and the guide surface 19 overlap with each other as described above. In particular, the leading end portion 27 comes into contact with the roll paper 5 on a wide surface. Further, damage to the roll paper 5 can be further avoided.

Next, the configuration of the paper detection unit 8 will be described in detail. FIG. 5 is a front view showing the paper detection unit in the absence of roll paper. FIG. 6 is a front view showing the paper detection unit in the presence of roll paper. FIG. 5 is a view of the paper detection unit 8 shown in FIG. 2 as viewed from the arrow B, and FIG. 6 is a diagram B ′ of the paper detection unit 8 shown in FIG.
It is a figure by an arrow view.

As shown in FIG. 5, the paper detection unit 8 is arranged along the direction in which the buffer plate 14 extends in a storage unit 16 provided by cutting the buffer plate 14. The paper detection unit 8 includes a detection lever rotation center 1
A detection lever 17 that rotates about 8, a cam 20 that is provided integrally with the detection lever 17,
An arc surface 21 which is one surface of the cam 20 and concentric with the detection lever rotation center 18, and a mechanical switch 2
2 and a switch lever 23 that rotates in contact with the cam 20 and operates the mechanical switch 22. The leading end 27 of the detection lever 17 is rounded so as not to damage the roll paper 5.

The mechanical switch 22 has a switch lever rotation center 2 that is the rotation center of the switch lever 23.
6 and a contact lever 24 with which the switch lever 23 abuts. The contact lever 24 is a conductive metal having elasticity, and when the switch lever 23 rotates and contacts, the contact lever 24 flexes flexibly in accordance with the rotation of the switch lever 23. A contact portion between the switch lever 23 and the contact lever 24 is a contact portion 25, and the switch lever 23 and the contact lever 24 are electrically connected via the contact portion 25.

In the state where the roll paper 5 is not loaded in the printing apparatus 1, the paper detection unit 8 detects the detection lever 17.
Is rotated by the weight on the opposite side of the cam 20 across the tip 27 and the detection lever rotation center 18, and the tip 27 is at a position P protruding from the guide surface 19 of the buffer plate 14. At this time, the switch lever 23 is free from the cam 20 and is separated from the contact portion 25 of the contact lever 24, and the electrical continuity is OFF. The switch lever 23 returns to the position of this electrical OFF state by a spring or the like (not shown) in a state where no external force is applied by the cam 20 or the like. The switch lever 23 sets this position as the origin position. When the switch lever 23 is at the origin position and is in the electrically OFF state, it can be detected that the roll paper 5 is not present in the printing apparatus 1.

Then, as shown in FIG. 6, when the roll paper 5 is loaded into the printing apparatus 1, the leading end 27 is pushed down by the roll paper 5 and rotates from the position P to the position Q. The end of the cam 20 pushes the switch lever 23 by the rotation of the distal end portion 27 and rotates the switch lever 23 around the switch lever rotation center 26. When the distal end portion 27 rotates to the position Q, the switch lever 23 changes from being pushed by the end portion of the cam 20 onto the arc surface 21. In a state where the switch lever 23 rides on the circular arc surface 21, the switch lever 23 and the contact lever 24 come into contact with each other at the contact portion 25 and are electrically turned on. From this electrical ON state, it can be detected that the roll paper 5 is present in the printing apparatus 1.

In a normal printing state, the roll paper 5 is in the roll paper position R1 and is in contact with the leading end portion 27. When printing is started from the printing stopped state, tension is applied to the roll paper 5 so that the buffer plate 1
4 rotates and the roll paper 5 moves to the roll paper position R2. When the start and stop of printing are repeated and the buffer plate 14 rotates each time, the roll paper 5 is positioned at the roll paper position R1 and the roll.
Move between the paper position R2. In conjunction with this, the tip portion 27 rotates. The arc surface 21 of the cam 20 also rotates with the rotation of the distal end portion 27. However, since the switch lever 23 is in a state of riding on the arc surface 21, the switch lever rotation center only slides on the arc surface 21. 26
It does not rotate around. Therefore, the switch lever 23 and the contact lever 24 do not slide at the contact portion 25, and unnecessary sliding of the contact portion 25 can be suppressed. In addition, poor electrical continuity due to wear of the contact portion 25 can be reduced.

The embodiments of the roll paper transport device and the printing device 1 have been described above. The effect of this embodiment is described collectively.

(1) In the roll paper transport device, the paper detection unit 8 is stored in the storage unit 16 of the buffer mechanism unit 7, and the respective functions are maintained without interfering with each other. Therefore, the occupied installation space for the paper detection unit 8 alone is almost unnecessary, and the space saving of the roll paper transport device and the printing apparatus 1 including the roll paper transport device can be realized.

(2) The distal end portion 27 of the detection lever 17 that comes into contact with the roll paper 5 is configured to have a rotation surface substantially parallel to the extending direction of the buffer plate 14. That is, the front end portion 27 has the roll portion 6 and the platen 1.
No rotational movement deviates from the distance L2 from zero. This eliminates the need for a new space for the tip 27 to rotate.

(3) When tension is applied to the roll paper 5, the buffer plate 14 rotates in a direction that relaxes the tension. The rotation of the buffer plate 14 prevents the roll paper 5 from being stretched, wrinkled, cut, and the like due to excessive tension, and avoids overloading the motor that rotates the platen 10 to damage the motor.
Step-out can be prevented. Moreover, it is possible to prevent printing defects caused by them.

(4) The distal end portion 27 of the detection lever 17 is configured not to protrude from the guide surface 19 in the direction of the roll paper 5 alone. With this configuration, it is possible to prevent the leading end portion 27 from pushing up the roll paper 5 and hitting or rubbing it, thereby preventing the roll paper from causing streaks, dents, and the like, and the print quality of the printed roll paper 5 can be secured satisfactorily. is there.

(5) The roll paper 5 is detected by operating the mechanical switch 22 via the detection lever 17 and the switch lever 23. Even if the pressure of the roll paper 5 acting on the detection lever 17 is a small pressure, it is possible to operate the mechanical switch 22 by pressing it strongly depending on the length ratio of each lever.

(6) The detection lever 17 has a distal end 27 side and a cam 20 side with the detection lever rotation center 18 in between. The weight balance is heavier on the cam 20 side, and when there is no roll paper 5, the detection lever 17 rotates so as to return the switch lever 23 to the home position by its own weight on the cam 20 side. The return to origin of the mechanical switch 22 can be controlled only by the detection lever 17 having the cam 20.

(7) Even if the detection lever 17 repeats a slight rotation as the roll paper 5 is conveyed, the cam 2
Since the switch lever 23 moves on the same arc surface 21 of 0, sliding between the switch lever 23 and the contact lever 24 of the mechanical switch 22 can be suppressed to a minimum, and contact wear and contact wear due to repeated slight slides. It is possible to prevent poor electrical continuity. Therefore, the durability of the mechanical switch 22 can be improved.

(8) The paper detection unit 8 only needs to be arranged so as to be accommodated in the accommodation unit 16 that is a cutout part of the buffer plate 14, and the layout of the size of the detection lever 17 and the arrangement position of the mechanical switch 22 and the like. There is freedom.

(9) The mechanical switch 22 which is less expensive than a photosensor or the like can be used, and the cost of the roll paper transport device and the printing apparatus 1 including the roll paper transport device can be reduced.

In addition, the present invention is not limited to the above-described embodiment, and the following modifications can be given.

(Modification 1) The shape of the detection lever 17 of the paper detection unit 8 is shown in FIGS. 5 and 6 if the balance setting is arranged such that the leading end 27 is at the position P when the roll paper 5 is not present. The shape is not limited to a crank shape. For example, it may be L-shaped or linear. Thereby, the freedom degree of the shape of the detection lever 17 can be increased.

(Modification 2) Further, as the degree of freedom of the shape of the detection lever 17 increases, the detection lever 17
The arrangement positions of the cam 20, the arc surface 21 and the mechanical switch 22 are not limited to specific positions. For example, the detection lever 17, the cam 20, the circular arc surface 21, and the mechanical switch 22 are connected to the buffer plate 1.
4 can be set so as to extend substantially linearly in parallel with the installation direction. Conversely, it is possible to set the detection lever 17, the cam 20, the circular arc surface 21, and the mechanical switch 22 to extend in a direction orthogonal to the direction in which the buffer plate 14 is installed.

(Modification 3) The shape of the guide surface 19 of the buffer plate 14 may be an arcuate surface centered on the buffer plate rotation center 15 instead of the curved surface shown in FIG. With such an arc-shaped surface, even if the buffer plate 14 rotates, it is possible to substantially prevent the roll paper position from moving as the roll paper positions R1 and R2.

(Modification 4) The printing apparatus 1 including the buffer mechanism unit 7 and the paper detection unit 8 is not limited to printing using a thermal head, and may use a head such as a dot impact head or an inkjet head. The present invention is not limited to the printing method and can be applied to many types of printing apparatuses.

DESCRIPTION OF SYMBOLS 1 ... Printing apparatus, 4 ... Cover, 5 ... Roll paper, 6 ... Roll part, 7 ... Buffering mechanism part, 8 ... Paper detection part, 9 ... Print head, 10 ... Platen, 14 ... Buffer board, 16 ... Storage part, 17 ... detection lever,
DESCRIPTION OF SYMBOLS 18 ... Detection lever rotation center, 19 ... Guide surface, 20 ... Cam, 21 ... Arc surface, 22 ... Mechanical switch, 23 ... Switch lever, 24 ... Contact lever, 25 ... Contact part, 27 ... Tip part.

Claims (2)

A roll paper transport device for transporting roll paper,
A paper detection unit for detecting the presence or absence of the roll paper;
The paper detection unit is configured to detect a roll paper, and when detecting contact with the roll paper, a detection lever that is rotatable around a first rotation center ;
A cam integrally formed with the detection lever and having an arc surface concentric with the rotation center of the detection lever;
And arcuate surface abutting said cam, and switch lever rotatable about a second rotation center,
A contact lever capable of contacting the switch lever ,
When the detection lever rotates,
The cam rotates about the first rotation center, and the arc surface abuts on the switch lever.
The roll paper transport device , wherein the switch lever rotates around the second rotation center and contacts the contact lever .
A roll unit containing roll paper in a roll shape;
The printing apparatus comprising the roll paper conveying device according to claim 1 , wherein the printing is performed by conveying the roll paper accommodated in the roll unit.

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