JPH10114091A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal printer in which a platen roller can be removed easily. SOLUTION: The thermal printer 1 comprises a thermal head 4 supported on a body frame 2 while being positioned, and a platen roller 7 supported rotatably on the body frame 2 wherein printing is performed on a thermal sheet clamped by means of the thermal head 4 and the platen roller 7. The body frame 2 is provided with a groove 21 for supporting the bearing 12 of the platen roller 7 removably at a printing position while positioning. A cover frame 3 is fixed rotatably to the body frame 2 in order to regulate movement of the bearing 12 of platen roller 7 in the detaching direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM (A
The present invention relates to a thermal printer used for an automatic teller machine (automatic teller machine) or the like.

[0002]

2. Description of the Related Art Conventionally, in this type of ATM, a thermal printer that prints on a sheet by a heat-sensitive method is often used.

In general, a thermal printer sandwiches a heat-sensitive sheet conveyed to a printing unit between a heat-sensitive head having a plurality of heating elements and a platen roller driven to rotate, and conveys the sheet by rotating the platen roller. By doing so, predetermined printing or the like is performed on the sheet.

[0004]

In the case of a thermal printer having such a structure, if a press mark or the like is present on the outer peripheral surface of the platen roller, or if paper dust adheres to the surface of the thermal head or the platen roller, Printing failure occurs, and a high-precision image cannot be obtained. Therefore, in the thermal printer, to replace the platen roller,
Further, in order to perform the maintenance, it is necessary to remove the platen roller.

However, in the case of the conventional thermal printer, since the platen roller is incorporated in the main body frame, it has to be disassembled to remove it.
There was a problem that it took time.

On the other hand, there has been proposed a thermal printer configured so that the platen roller can be easily removed (for example, see JP-A-4-219260, JP-A-6-155828).

However, even in the case of such a thermal printer, there is a problem that it takes a considerable amount of time to remove the platen roller.

On the other hand, in this type of thermal printer, an auxiliary roller is pressed against a platen roller so that the sheet can be easily pulled in, the sheet is sandwiched between the rollers, and the sheet is conveyed toward a thermal head. It has been known.

However, in such a thermal printer, if the auxiliary roller is pressed against the platen roller,
The pressing force may cause the surface of the platen roller to be compressed and deformed to form imprint marks, thereby causing printing failure.

In order to avoid such a problem, the pressing force of the auxiliary roller on the platen roller may be reduced. However, if the pressing force of the auxiliary roller on the platen roller is reduced, a sheet having a large roll diameter may be used. In addition, there is a problem that the sheet cannot be smoothly fed into the printing unit.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the related art, and it is an object of the present invention to provide a thermal printer which can easily remove a platen roller. is there.

Another object of the present invention is to provide a thermal printer capable of performing smooth conveyance and printing of a recording sheet under optimum conditions.

[0013]

According to a first aspect of the present invention, there is provided a heat-sensitive head positioned and supported by a main body frame, and a platen roller rotatably supported by the main body frame. In a thermal printer that sandwiches a heat-sensitive sheet between these heat-sensitive heads and a platen roller and performs predetermined recording on the heat-sensitive sheet, a support groove portion that positions and supports the shaft portion of the platen roller at a printing position in a detachable state is described. A cover frame is provided on the main body frame described above, and a cover frame for restricting movement of the shaft portion of the platen roller in the separating direction in a state where the shaft portion of the platen roller is supported by the support groove.

In this case, as in the invention according to claim 2,
The invention according to claim 1, further comprising an elastic member for pressing the thermal head against the platen roller, and a support member connected to the elastic member, wherein the cover frame is supported by the main body frame so as to be freely opened and closed, and It is also effective to be configured to be locked to the above-mentioned support member in a closed state.

According to a third aspect of the present invention, there is provided a platen roller rotatably supported by the main body frame, a heat-sensitive head pressed against the platen roller, and an auxiliary roller pressed against the platen roller. In a thermal printer in which a recording sheet is nipped by the platen roller and the auxiliary roller and conveyed toward the thermal head, and the recording sheet is nipped by the platen roller and the thermal head to perform predetermined recording. A cam-shaped switching lever for bringing the thermal head into and out of contact with the platen roller, and the auxiliary roller can be brought into and out of contact with the platen roller by the switching lever. .

In this case, as in the fourth aspect of the present invention,
In the third aspect of the present invention, it is also effective that the thermal head and the auxiliary roller can be simultaneously pressed against the platen roller.

Further, in the invention according to any one of the third and fourth aspects, it is also effective that the thermal head and the auxiliary roller can be simultaneously separated from the platen roller. It is a target.

In the case of the first aspect of the present invention having such a structure, a support groove portion for positioning and supporting the shaft portion of the platen roller at the printing position in a detachable state is provided in the main body frame, and the shaft portion of the platen roller is formed as described above. By providing a cover frame that restricts the movement of the shaft portion of the platen roller in the detaching direction in a state where the platen roller is supported by the support groove portion, the platen roller can be removed simply by releasing the restriction by the cover frame.

In this case, as in the second aspect of the present invention,
The invention according to claim 1, further comprising an elastic member for pressing the thermal head against the platen roller, and a supporting member connected to the elastic member, wherein the cover frame is supported by the main body frame so as to be openable and closable, and is closed. If it is configured to be locked to the above-mentioned support member in a state where the cover frame is closed, the platen roller is positioned only by closing the cover frame, and an elastic member or the like for fixing the cover frame in the closed state There is no need to provide

On the other hand, by opening the cover frame, the regulation by the cover frame is released, and the platen roller can be easily removed.

According to the third aspect of the present invention, there is provided a cam-shaped switching lever for bringing the thermal head into and out of contact with the platen roller, and the switching lever connects the auxiliary roller to the platen roller. By making it possible to make contact and separation, the thermal head and the auxiliary roller can be made to contact and separate from the platen roller as needed, so that the recording sheet can be conveyed and printed under optimum conditions.

For example, if the auxiliary roller is separated from the platen roller when not in use, there is no possibility that a trace of a press mark will be formed on the platen roller. Therefore, the auxiliary roller can be pressed with a strong force against the platen roller. As a result, even when a large-diameter roll-shaped recording sheet is used, it is possible to smoothly convey the recording sheet toward the thermal head.

In this case, as in the fourth aspect of the present invention,
According to the third aspect of the invention, if the thermal head and the auxiliary roller can be simultaneously pressed against the platen roller, printing can be performed in a state where the recording sheet is in close contact with the platen roller.

According to the third aspect of the present invention, if the thermal head and the auxiliary roller can be simultaneously separated from the platen roller, a pressing force is applied to the platen roller. Therefore, compression deformation of the platen roller can be prevented.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the thermal printer according to the present invention will be described below in detail with reference to the drawings.

1 to 3 show the entire structure of the thermal printer according to the present embodiment. FIG. 1 is a perspective view showing a state in which a cover frame is opened, and FIG. 2 is a view showing a state in which the cover frame is closed. FIG. 3 is a side view showing a state where the cover frame is opened, and FIG. 4 is a side view showing a state where the cover frame is closed.

The thermal printer 1 according to the present embodiment generally comprises a main body frame 2 and a cover frame 3 which is attached to the main body frame 2 so as to be openable and closable.

A thermal head 4 for printing on a recording sheet (not shown) is provided at the front of the metal main body frame 2.
Is provided. The heat-sensitive head 4 is made of a plate-like member having substantially the same width as both sides 2a and 2b of the main body frame 2, and a head support shaft 4a is provided at one end of each side. The head support shaft 4a is engaged with and supported by a part of a support groove 20 formed on both sides 2a and 2b of the main body frame 2. An engagement pin 4b is provided on one side of the thermal head 4 at a position away from the head support shaft 4a.
a and 2b are engaged with and supported by a part of the support groove 20.

A pair of coil springs 6 fixed to a flat head pressing plate 5 are attached to the back of the thermal head 4. On both sides of the head pressing plate 5, an engagement pin 5a, which will be described later, is provided at one end, and an engagement piece 5b is provided at the other end, and the engagement pin 5a and the engagement piece 5b are provided. The head pressing plate 5 is supported by the main body frame 2 by engaging with a part of the support groove 20 of the main body frame 2. The thermal head 4 and the head pressing plate 5 are configured to be urged in a direction in which the thermal head 4 and the head pressing plate 5 are separated from each other by the pressing force of the coil spring 6.

Here, the thermal head 4 is rotatable about the head support shaft 4a, and the head pressing plate 5 is rotatable about the engaging piece 5b, so that both sides 2a, 2b of the main body frame 2 can rotate.
It is supported by.

On both sides 2a, 2b of the body frame 2,
In the vicinity of the thermal head 4, a support groove 21 for positioning and supporting the platen roller 7 is provided.

The platen roller 7 is fixed to a platen shaft 8, and a drive gear 9 for driving the platen roller 7 is fixed to one end of the platen shaft 8. A gear train (not shown) is provided so that the torque of the drive motor 10 is transmitted to the drive gear 9 when the platen roller 7 is mounted. In addition, as the drive motor 10, for example, a stepping motor is used.

On the other hand, a switching lever 11 made of, for example, resin is rotatably supported at the other end of the platen shaft 8. On both sides of the platen roller 7, bearings 12 are rotatably mounted between the drive gear 9 and the switching lever 11, respectively. Each of the bearings 12 is configured to engage with the support grooves 21 of both sides 2a and 2b of the main body frame 2, and the platen roller 7 is detachable from the main body frame 2 by such a configuration.

A guide member 13 made of, for example, resin is provided inside the main body frame 2 to guide the recording sheet. The guide member 13 is formed so that its surface is inclined downward toward the thermal head 4. An auxiliary roller 14 is provided near the thermal head 4 so that the surface thereof is exposed from a cutout provided in the guide member 13.
Is provided.

The auxiliary roller 14 is attached to both sides 2a and 2b of the main body frame 2 so as to be rotatable about a rotation shaft 15. In this case, as shown in FIG.
Is configured to engage with a long hole 16 provided in both side plates 2 a and 2 b of the main body frame 2. As shown in FIG. 5, the elongated hole 16 is formed to extend from below the platen roller 7 toward the center of the platen shaft 8, and the auxiliary roller 14 is urged by the platen roller 7 by a coil spring 17. It is configured as follows.

On the other hand, a guide member 18 made of, for example, metal is provided at a rear portion of the main body frame 2 in order to form an insertion slot for a recording sheet.

A limit switch 19 for detecting the position of the thermal head 4 with respect to the platen roller 7 is provided on one side 2a of the main body frame 2. This limit switch 19 is a micro switch (not shown). Connected to the controller.

On the other hand, the cover frame 3 is formed, for example, by bending a metal plate-like member into a substantially U-shape, and the both sides 3a, 3b are rotatable about the support shaft 30. Attached to. Hooks 31a and 31b are provided on both sides of the front portion of the cover frame 3 so as to extend in the rotation direction of the cover frame 3. Then, as shown in FIG. 3 and FIG.
a, a cut-out portion 32a formed at the root portion of 31b,
32b is configured to engage with an engaging pin 4b provided on the head pressing plate 5.

A guide portion 3c for guiding a recording sheet is provided inside the cover frame 3. The guide portion 3c is formed, for example, by bending the cover frame 3 inward. In a state where the cover frame 3 is closed, the recording sheet is configured to be parallel to the surface of the guide member 13 of the main body frame 2 to form a recording sheet conveyance path.

Further, a slit-shaped discharge port 33 for discharging a recording sheet is provided at a front portion of the cover frame 3.

Further, a sensor 34 for detecting the presence of a recording sheet is provided near the guide section 3, and this sensor is connected to a microcontroller (not shown).

As shown in FIG. 3, when the platen roller 7 is mounted on the main body frame 2, the bearing 12 is supported by engaging with the support groove 21 so that the flat positioning portion 12a faces upward. . As shown in FIG. 4, when the cover frame 3 is closed, the edges 3d and 3e of the both sides 3a and 3b are configured to abut the positioning portions 12a of the bearings 12.

FIG. 5 shows a configuration near the switching lever 11 in the present embodiment.

As shown in FIG. 5, the switching lever 11 has
A plurality of notches 11a, 11b, 11 as cams
c, 11d, 11e, and 11f are formed. Of these, the notches 11a and 11b have the same depth,
That is, it is formed at a position at an equal distance from the platen shaft 8. The notches 11c and 11e are also formed at the same depth. On the other hand, the notch portions 11d and 11f
It is formed deeper than the notches 11c and 11e. Further, a convex portion 11g is formed adjacent to the cutout portion 11e.

When the platen roller 7 is mounted on the main body frame 2, the lever 110 of the switching lever 11 is rotated so that the notches 11 a to 1
1f is the engagement pin 4b of the thermal head 4, the auxiliary roller 14
Rotating shaft 15 and drive lever 1 of limit switch 19
9a to engage with each other.

FIGS. 6 and 7 show the locking position of the switching lever 11 when the recording sheet is pulled in, for example.

In the position shown in FIG.
Is engaged with the notch 11a of the switching lever 11 to separate the heating element 40 of the thermal head 4 from the platen roller 7, and the rotating shaft 1 of the auxiliary roller 14
5 is engaged with the notch 11 e of the switching lever 11, and the auxiliary roller 14 is separated from the platen roller 7. Then, the drive lever 19a of the limit switch 19 is engaged with the projection 11g of the switching lever 11 and is kept in the ON state, and the platen roller 7 is in a rotatable state.

In this state, since the platen roller 7 and the auxiliary roller 14 are separated from each other, the leading end of the recording sheet can be easily inserted between them, or a paper sheet can be easily removed at the time of paper jam. Can also be removed. Further, when the printer is not used for a long period of time or when the printer is transported, this state can be attained.
While the heating element 40 is protected, it is possible to prevent indentations from occurring on the outer peripheral surface of the platen roller. As shown in FIG. 7, when the lever portion 110 of the switching lever 11 is pressed down, the engagement pin 4b of the thermal head 4
The heating element 40 of the thermal head 4 is separated from the platen roller 7 by engaging with the notch 11b, but the rotary shaft 15 of the auxiliary roller 14 enters the notch 11f formed deeper. The auxiliary roller 14 is pressed against the platen roller 7 by the urging force of the coil spring 17,
The recording sheet is sandwiched between them.

In this case, the drive lever 19a of the limit switch 19 is held in the ON state by engaging with the projection 11g of the switching lever 11. When the platen roller 7 is rotated in this state, the auxiliary roller 14 Following this, the recording sheet is drawn toward the thermal head 4. On the other hand,
Since the platen roller 7 and the heating element 40 of the thermal head 4 are separated from each other, the leading end of the recording sheet passes through them and is easily pulled out above the thermal head 4. As described above, since the end surface of the leading end of the recording paper to be inserted does not come into contact with the heating element, it is possible to provide a printer equipped with an auto-loading function in which the life of the heating head is extended. In particular, when using recording paper to which a label is attached, the lever 11
If 0 is a mechanism that controls its rotation with a plunger or the like,
Not only can the heating element 40 be prevented from being damaged by the step of the label, but also the adhesive of the label can be prevented from adhering to the thermal head 4, so that the effect is large, such as less maintenance of the head cleaning. It is.

In order to stop the platen roller 7 at a predetermined position, for example, the leading end of the recording sheet is detected by the sensor 34 and the platen roller 7 and the auxiliary roller 14 are detected.
Then, the driving motor 10 may be rotated by a predetermined number of steps after the recording sheet is nipped.

FIGS. 8 and 9 show the locking position of the switching lever 11 when, for example, printing on a recording sheet.

In the position shown in FIG.
The engagement pin 4b is provided with a notch 11a of the switching lever 11,
11b, the thermal head 4 does not engage with the coil spring 6
Urges the platen roller 7. On the other hand, the rotation shaft 15 of the auxiliary roller 14 is
1c, the auxiliary roller 14 is separated from the platen roller 7. Further, the limit switch 19
Of the switching lever 11 is disengaged from the drive lever 19a, and the limit switch 19 is kept in the off state.

In this state, predetermined printing or the like can be performed on the recording sheet by operating the thermal head 4 and the drive motor 10 based on a signal from a microcontroller (not shown).

In addition, there is no trace of pressing marks on the recording paper by the auxiliary roller 14, and the recording paper can be kept in a good condition without wrinkling.

As shown in FIG. 9, when the lever portion 110 of the switching lever 11 is lowered from the state shown in FIG.
4 is provided with a notch 11 formed more deeply.
In order to enter d, the auxiliary roller 14 is pressed against the heating element 40 of the platen roller 7 by the urging force of the coil spring 6. In this case, since the engagement between the drive lever 19a of the limit switch 19 and the projection 11g of the switching lever 11 is still released, the limit switch 19 is kept in the off state.

In this state, printing or the like can be performed while the recording sheet is in close contact with the platen roller 7.

In this case, the recording quality can be improved because the recording paper having low rigidity can be brought into close contact with the platen.
Further, when paper feeding only by pressing the thermal head is insufficient, such as when using a recording paper having a large roll diameter,
Due to the increase in the frictional force and winding angle due to the auxiliary roller,
The paper feeding ability can be improved.

As described above, according to the present embodiment,
The platen roller 7 is easily opened simply by opening the cover frame 3.
Can be removed, and the replacement and maintenance work of the platen roller 7 can be performed easily.

Further, since the conveyance path of the recording sheet can be largely exposed, when a jam occurs, the processing can be easily performed.

Further, the platen roller 7 is positioned only by closing the cover frame 3, and the cover frame 3 is notched by the notches 32 of the hooks 31a and 31b.
a, 32b and the engaging pin 5a of the head pressing plate 5 are engaged, so that there is no need to provide an elastic member or the like for fixing the cover frame 3 in a closed state.
The device configuration can be simplified.

Further, according to the present embodiment, the platen roller 7, the thermal head 4, and the auxiliary roller 14 can be brought into contact with and separated from each other by switching the switching lever 4, so that recording is performed under optimum conditions as necessary. It becomes possible to convey a sheet, perform printing, and the like.

For example, as shown in FIG. 8, if the auxiliary roller 15 is separated from the platen roller 7 when not in use, there is no danger that imprint marks will be formed on the platen roller 7 and the recording paper. Roller 7
As a result, even when a large-diameter roll-shaped recording sheet is used, the recording sheet can be smoothly conveyed toward the thermal head 4. .

In particular, as shown in FIG. 6, if the thermal head 4 and the auxiliary roller 14 are simultaneously separated from the platen roller 14, no pressing force is applied to the platen roller 7, so that the platen roller 7 can be prevented from being deformed, and the life of the platen roller 7 can be extended.

On the other hand, as shown in FIG. 9, if the heat-sensitive head 4 and the auxiliary roller 14 can be pressed against the platen roller 7 at the same time, printing can be performed with the recording sheet in close contact with the platen roller 7. And the quality of printing and the like can be improved.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes can be made.

For example, in the above-described embodiment, the switching lever is provided on the rotating shaft of the platen roller. However, the heat-sensitive head and the auxiliary roller can be moved toward and away from the platen roller in conjunction with each other. If there is, it is not always necessary to provide it on the rotation shaft of the platen roller. However, if the switching lever is provided with a platen roller as in the above-described embodiment, the heat-sensitive head and the auxiliary roller can be brought into and out of contact with a simpler configuration.

Further, the shape of the hook of the cover frame and the shape of the cam of the switching lever are not limited to the above-described embodiment, but various shapes can be adopted.

Further, the switching lever can be driven either manually or by an electric actuator.

[0069]

As described above, according to the first aspect of the present invention, a support groove for positioning and supporting a shaft portion of a platen roller at a printing position in a detachable state is provided in a main body frame. By providing a cover frame that restricts the movement of the shaft portion of the platen roller in the detaching direction in a state where the shaft portion is supported by the above-described support groove portion, the platen roller can be easily removed, and replacement and maintenance of the platen roller can be performed. Work can be done easily.

In this case, as in the second aspect of the present invention,
The invention according to claim 1, further comprising an elastic member for pressing the thermal head against the platen roller, and a supporting member connected to the elastic member, wherein the cover frame is supported by the main body frame so as to be openable and closable, and is closed. By being configured to be locked to the above-described support member in a state where the cover is opened, it is possible to obtain a thermal printer having a simple configuration in which the platen roller can be easily positioned and removed according to the opening and closing of the cover frame.

On the other hand, according to the third aspect of the present invention, a cam-shaped switching lever for bringing the thermal head into and out of contact with the platen roller is provided, and the auxiliary roller is connected to the platen roller by the switching lever. By making it possible to make contact and separation, it is possible to obtain a thermal printer capable of performing smooth conveyance and printing of a recording sheet under optimum conditions.

In particular, as in the invention of the fourth aspect, in the invention of the third aspect, the recording sheet is brought into close contact with the platen roller by simultaneously pressing the heat-sensitive head and the auxiliary roller against the platen roller. In such a state, printing or the like can be performed, and the quality of printing or the like can be improved.

According to the fifth aspect of the present invention, the heat-sensitive head and the auxiliary roller can be simultaneously separated from the platen roller to prevent the platen roller from being deformed by compression. Thus, the life of the platen roller can be extended.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an overall configuration of an embodiment of a thermal printer according to the present invention, showing a state where a cover frame is opened.

FIG. 2 is a perspective view showing the entire configuration of the embodiment and showing a state in which a cover frame is closed.

FIG. 3 is a side view showing the entire configuration of the embodiment and showing a state where a cover frame is opened.

FIG. 4 is a side view showing the entire configuration of the embodiment and showing a state in which a cover frame is closed.

FIG. 5 is a configuration diagram showing the vicinity of a switching lever in the embodiment.

FIG. 6 is an explanatory diagram showing a locking position of a switching lever when both a thermal head and an auxiliary roller are separated from a platen roller in the embodiment.

FIG. 7 is an explanatory diagram showing an engagement position of a switching lever when only the thermal head is separated from a platen roller in the embodiment.

FIG. 8 is an explanatory diagram showing a locking position of a switching lever when only an auxiliary roller is separated from a platen roller in the embodiment.

FIG. 9 is an explanatory diagram showing a locking position of a switching lever when both a thermal head and an auxiliary roller are pressed against a platen roller in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Thermal printer 2 Body frame 2a, 2b side 20 Positioning groove 21 Positioning groove 3 Cover frame 3a, 3b Side 3c Guide 3d, 3e Edge 30 Support shaft 31a Hook 32a Notch portion 4 Thermal head 4a Head support shaft 4b Engagement pin 5 Head pressing plate 5a Engagement pin 6 Coil spring 7 Platen roller 8 Platen shaft 11 Switching lever 11a, 11b, 11c, 11d, 11e, 11f Notch 11g Convex part 110 Lever part 12 Bearing 14 Auxiliary roller 15 Rotation Shaft 16 Long hole 17 Coil spring 19 Limit switch 19a Drive lever

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toru Takami 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation

Claims (5)

[Claims] 1. A thermal head, which is positioned and supported by a main body frame, and a platen roller rotatably supported by the main body frame, wherein the thermal head and the platen roller sandwich a thermal sheet so as to be placed on the thermal sheet. In the thermal printer for performing predetermined recording, a support groove for positioning and supporting the shaft of the platen roller at a printing position in a detachable state is provided on the main body frame, and the shaft of the platen roller is supported by the support groove. A cover frame for restricting movement of a shaft portion of the platen roller in a detaching direction in a state where the platen roller is in a disengaged state. 2. An apparatus according to claim 1, further comprising an elastic member for pressing the thermal head against the platen roller, and a supporting member connected to the elastic member. 2. The thermal printer according to claim 1, wherein the thermal printer is locked to the support member in a state. 3. A platen roller rotatably supported by a body frame, a heat-sensitive head pressed against the platen roller, and an auxiliary roller pressed against the platen roller, wherein the auxiliary roller is pressed against the platen roller. In a thermal printer which sandwiches a recording sheet and conveys the recording sheet toward the heat-sensitive head, and performs predetermined recording while sandwiching the recording sheet by the platen roller and the heat-sensitive head, the thermal head relative to the platen roller A cam-shaped switching lever for moving the auxiliary roller toward and away from the platen roller by the switching lever. 4. The thermal printer according to claim 3, wherein the thermal head and the auxiliary roller can be simultaneously pressed against the platen roller. 5. The thermal printer according to claim 3, wherein the thermal head and the auxiliary roller can be simultaneously separated from the platen roller.