JP2003237118A - Thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal printer in which the size can be reduced by decreasing the number of components and the manufacturing cost can be reduced by simplifying the assembling work. <P>SOLUTION: The thermal printer comprises a frame (F) having a pair of sidewall parts disposed oppositely at a specified interval in the widthwise direction of a sheet, a line thermal head (H) for performing printing, a platen roller (1) having a circumferential surface abutting against the line thermal head, means for pressing the back of the line thermal head so that the line thermal head comes into pressure contact with the surface of the platen roller, a motor (M) as a drive source, and a gear transmission mechanism (G1) for transmitting the rotary driving power of the motor to the platen roller, wherein the pressing means is composed of a part of the compositional member of the frame coming into pressure contact with the back face of the head support (e.g. a pressing part 10 composed of a part of the frame). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small thermal printer mounted on various portable information equipments,
In particular, the present invention relates to a thermal printer that can simplify the configuration of a pressing unit that presses the line thermal head so that the line thermal head is pressed against the surface of the platen roller.

[0002]

2. Description of the Related Art A conventional general line dot type thermal printer comprises a line thermal head and a platen roller which are installed in a frame so as to face each other, a driving means for the line thermal head, and a thermal recording sheet conveying mechanism.

Here, referring to the exploded perspective view of FIG.
A configuration example of a conventional thermal printer will be described.

As shown in FIG. 10, the thermal printer P
Reference numeral 2 denotes a platen roller 102, a thermal head H, two coil springs 104 that apply a biasing force to press the thermal head H against the platen roller 102, and a lock that rotatably supports both ends of a rotary shaft 102A of the platen roller 102. An arm member 105, a motor M as a drive source, a gear transmission mechanism G2 for transmitting a rotational driving force of the motor M to a driven gear g10 fixed to one end 102A of the platen roller 102, and the like are attached to the resin-molded frame 101. ing.

In FIG. 10, reference numeral 200 denotes a head support which also serves as a heat dissipation member of the thermal head H, and 300.
Is a bearing member of the rotating shaft 102A of the platen roller 102,
A sensor 400 detects the edge of the recording sheet.

The lock arm member 105 is substantially U-shaped as a whole and engages with both ends of the rotation shaft of the platen roller 102 so that the surface of the platen roller 102 is covered with the thermal head H.
A pair of hook-shaped rotating shaft support portions (latch portions) 105a that are drawn so as to be pressed against the thermal head H, and the latch portion 105a via both sides of the thermal head H.
Of the pair of arm portions 105b that are guided to the rear of the
5b is provided at both ends and is provided in the width direction behind the thermal head H, and elastic member supporting portions 105c for supporting the coil spring 104 are provided. The lock arm member 1
05 and the thermal head H are rotatably supported on both side surfaces of the frame 101 via a rotation shaft 500. Reference numeral 700 is a screw for fixing the motor M to the frame 101.

[0007]

By the way, the thermal printer having the above-mentioned structure is mounted on, for example, a portable information terminal. These information terminals and the like are required to be further downsized in order to enhance portability and convenience, and further reduction in manufacturing cost is required in order to enhance price competitiveness. Such demands also apply to the thermal printer itself as a component of the information terminal, and further downsizing and cost reduction are required.

To reduce the size and cost of the thermal printer,
It is considered effective to reduce the number of parts and simplify the assembly work to reduce the manufacturing cost.

However, the conventional thermal printer P described above is used.
2, the mounting positions and the mounting directions of the respective constituent members (the platen roller 102, the thermal head H, the head support 200, the gear transmission mechanism G, etc.) with respect to the frame 101 are different as shown in FIG. It was complicated and required skill.

The present invention has been devised in order to solve the above-mentioned problems, and the thermal printer is capable of reducing the number of parts to achieve miniaturization and simplifying the assembling work to reduce the manufacturing cost. The purpose is to provide.

[0011]

In order to achieve the above-mentioned object, a thermal printer according to the present invention comprises a frame (F) having a pair of side wall portions facing each other at a predetermined interval in the paper width direction, A line thermal head (H) for printing, a platen roller (1) whose peripheral surface is in contact with the line thermal head, and the line so that the line thermal head is pressed against the surface of the platen roller. A thermal printer comprising at least a pressing means for pressing the back surface of the thermal head, a motor (M) as a drive source, and a gear transmission mechanism (G1) for transmitting the rotational driving force of the motor to the platen roller. The means is a part of a constituent member of the frame that is pressed against the back surface of the head support (for example, a pressing portion that is composed of a part of the frame. 0) was to be composed of.

As a result, the pressing means (members such as coil springs) provided in the conventional printer can be eliminated to reduce the number of parts, and the printer can be downsized and the manufacturing cost can be reduced. Further, since the work of incorporating a coil spring or the like is unnecessary, the assembling work can be simplified and the manufacturing cost can be further reduced.

The frame is composed of a lower frame member and an upper frame member, which are vertically separable.
A part of a constituent member of the frame forming the pressing means is an elastic pressing portion integrally formed with the upper frame member, and the pressing portion connects the upper frame member to the lower frame member. The end portion of the pressing portion can be formed at a position where it abuts against the back surface of the line thermal head when fitted to the. This makes it possible to configure the pressing means with a simple structure and reduce the manufacturing cost.

The frame is composed of a lower frame member and an upper frame member which are vertically separable.
A part of a constituent member of the frame which constitutes the pressing means is a pressing portion which is integrally formed with the upper frame member and which has rigidity, and the pressing portion connects the upper frame member to the lower frame member. The end portion of the pressing portion may be formed at a position where it abuts on the back surface of the head support member when the head support member is fitted to the head support member. This makes it possible to configure the pressing means with a simple structure and reduce the manufacturing cost.

The end portion of the pressing portion can also serve as a heat radiating portion that conducts heat of the line thermal head and releases it. Thus, for example, by constructing the head support with a metal having high thermal conductivity, it is not necessary to separately provide a heat dissipation member, and the number of parts can be reduced and the manufacturing cost can be reduced.

Further, a thermal printer according to another invention is a frame having a pair of side wall portions facing each other at a predetermined interval in the paper width direction, a line thermal head for printing, and a line thermal head for the line thermal head. And a peripheral surface of the platen roller, a pressing means for pressing the platen roller so that the line thermal head is pressed against the surface of the platen roller, a motor as a drive source, and a rotational driving force of the motor. And a gear transmission mechanism that transmits the platen roller to the platen roller, the pressing means presses the surface of the platen roller in parallel with the line thermal head to compress the surface of the platen roller. It is configured to include support members that rotatably support both ends of the.

As a result, the pressing means (members such as coil springs) provided in the conventional printer can be eliminated to reduce the number of parts, and the printer can be downsized and the manufacturing cost can be reduced. Further, since the work of incorporating a coil spring or the like is unnecessary, the assembling work can be simplified and the manufacturing cost can be further reduced.

Further, the supporting member is formed on both side wall portions of the frame, has an open portion at an upper portion thereof, and has a long groove having a locking portion at a lower end side located near the line thermal head, and the both grooves. While rotatably holding the rotary shaft of the platen roller inserted into the long groove through the opening of the long groove,
A bearing member engaged with the locking portion of the long groove, and each locking portion of the long groove is a position where the surface of the platen roller can be pressed in parallel with the line thermal head to compress the platen roller. Should be provided in the. As a result, the assembly process can be simplified and the manufacturing cost can be reduced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing a first embodiment of a thermal printer according to the present invention, and FIG. 2 is a perspective view showing an appearance of the assembled thermal printer.

As shown in FIG. 1, a thermal printer P1a according to the first embodiment has a lower frame member F1 and an upper frame member F1 having a pair of side wall portions arranged opposite to each other at a predetermined interval in the paper width direction. The frame F is composed of F2 and F2.

The frame F is made of, for example, a plastic injection molded product such as polycarbonate.

A structure in which the upper surface of the lower frame member F1 and the lower surface of the upper frame member F2 can be united (that is, a structure in which end surfaces have shapes corresponding to each other and no gap is formed when they are joined) In the joined state shown in FIG. 2, both frame members F1 and F2 are fixed by engaging tabs and screws that can be fitted.

The lower frame member F1 is formed with an accommodating portion A for accommodating the platen roller 1, the thermal head H, the motor M as a drive source, and the like. Although not shown in the figure, the storage portion A is provided with a groove or a notch for positioning the thermal head H. The thermal head H may be attached to a heat dissipation portion 11 of the side frame member F2 described later. As a result, the assembly work can be performed more efficiently. In addition, a support portion E3 for fixing the rear end portion of the motor M is formed in the storage portion A. Further, the thermal head H is provided with a connector 30 for connecting a signal line for transmitting a print signal.

The division planes of the lower frame member F1 and the upper frame member F2 are determined so that they are divided by a plane that passes through each bearing portion. When the bearings are completely overlapped in the vertical direction, the split structure of the lower frame member F1 and the upper frame member F2 cannot be dealt with. Therefore, the rotation axes of the gears g1 and g2 do not overlap in the vertical direction. Designed to be horizontally offset.

A driven gear g2 for fixing the rotational driving force of the motor M to one end of the rotary shaft 1A of the platen roller 1 is provided on one side wall side (the right side wall side in FIG. 1) of the lower frame member F1.
Each gear g1, g of the gear transmission mechanism G1 for transmitting to 0
2 and a gear storage portion B for storing the driven gear g20.

On the side wall of the lower frame member F1 and the upper end of the gear housing B, the rotary shaft 1A of the platen roller 1,
Semi-circular holders C1 to C3 that rotatably hold the rotation shafts g1a and g2a of the gears g1 and g2 and a semi-circular holder C4 that holds the bearing Ma of the motor M are formed. In the lower frame member F1, reference numeral 20
Is a guide portion when a roll paper as a recording paper (not shown) is conveyed. Further, on the lower surface side of the upper frame member F2, semicircular holding portions D1 to D3 (note that D4 does not appear in the drawing) are formed at positions facing the holding portions C1 to C3 of the lower frame member F1. Has been done.

On the upper surface side of the upper frame member F2, as shown in FIG.
, The line thermal head H is pressed against the surface of the platen roller 1.
An elastic V-shaped pressing portion 10a for pressing the back surface of the upper frame member F2 is integrally formed with the upper frame member F2.

Further, in FIGS. 1 and 9, reference numeral 11
Is a heat radiating portion that radiates heat from the thermal head H. The heat radiating portion 11 is formed integrally with the pressing portion 10 and radiates heat when the upper frame member F2 is fitted to the lower frame member F1. The end surface of the portion 11 is provided so as to come into contact with the back surface of the thermal head H.

The pressing portion 10a is the thermal head H.
When the thermal head H is in contact with the back surface of the platen, the thermal head H is pressed backward against the surface of the platen roller 1 with a predetermined pressing force. As a result, an appropriate pressure can be applied to the recording paper nipped between the line thermal head H and the platen roller 1 during printing.

Here, the thermal printer P1 having the above structure
The assembling procedure of a will be described. First, the motor M of the lower frame member F1 is placed in the storage portion A, and the gears g1, g2
The rotating shafts g1a and g2a of the above are placed on the holding portions C3 and C2 of the gear storage portion B. Next, the driven gear g20 is attached to one end of the rotary shaft 1A of the platen roller 1, and both ends of the rotary shaft 1A of the platen roller 1 are placed on the holding portion C1 of the lower frame member F1. At this time, the driven gear g2
0 is stored in the gear storage portion B.

Next, the line thermal head H is placed in the storage section A.
Then, the upper frame member F2 is finally fitted to the lower frame member F1. As a result, the platen roller 1
The rotating shafts of the gears g1, g2, etc. are rotatably held by the holding portions C1 to C4 and the holding portions D1 to D4, and the line thermal head H is attached to the surface of the platen roller 1 by the pressing portion 10a of the upper frame member F2. Pressed.

Then, the upper frame member F2 is fixed to the lower frame member F1 by the engagement of engaging claws or the screwing of screws, whereby the thermal printer P1a as shown in FIG. 2 is assembled.

As described above, the thermal printer P1 according to the present embodiment has the advantage that the number of parts can be reduced and the cost can be further reduced because the members such as the coil spring as the pressing means are eliminated.

Further, each component is replaced with a lower frame member F1.
It can be assembled only by a simple assembling work such that the upper frame member F2 is placed on the base plate and the upper frame member F2 is united, and it is possible to shorten the assembling time and reduce the manufacturing cost of the printer because the labor of incorporating the coil spring as the pressing means as in the past can be omitted. Can be reduced.

The pressing portion is not limited to the V-shaped portion as described above, but may be composed of a plate-like piece 10b curved upward as in the thermal printer P1b shown in FIG. 3, for example. May be. In this case, the pressing portion 1
In the state of being in contact with the back surface of the line thermal head H, 0b bends upward to bring the thermal head H into contact with the surface of the platen roller 1 with a predetermined pressing force. As a result, an appropriate pressure can be applied to the recording paper nipped between the line thermal head H and the platen roller 1 during printing.

Next, the thermal printer P1c according to the second embodiment will be described with reference to FIGS. The basic structure of the thermal printer P1c is the same as that of the thermal printer P1a (P1b) according to the first embodiment. The difference lies in the upper frame member F of the first embodiment.
The pressing portion 10a (10b) included in 2 has elasticity, whereas the pressing portion 10c in the second embodiment has rigidity. Therefore, the pressing portion 10c is designed to be thicker and more rigid than the pressing portion 10b (see FIG. 3) of the first embodiment. When the pressing portion 10c is made of a resin or metal having a high hardness, it is not always necessary to make it thick as long as a predetermined strength can be obtained.

Then, as shown in FIG. 5, the pressing portion 10c presses the line thermal head H against the surface of the platen roller 1 without bending in a state where it is in contact with the back surface of the line thermal head H. At this time, the surface of the platen roller 1 (generally made of hard rubber or the like) is appropriately compressed and crushed to generate a predetermined pressure. Therefore, at the time of printing, it becomes possible to apply an appropriate pressure to the recording paper nipped between the line thermal head H and the platen roller 1.

Next, a thermal printer P1d according to the third embodiment will be described with reference to FIGS. 6 and 7. Since the basic structure of the thermal printer P1d is the same as that of the first and second embodiments, the same reference numerals are given and the description thereof is omitted.

Thermal printer P1 according to the third embodiment
The difference of d from the first and second embodiments is that the line thermal head H presses the platen roller 1 by a pair of lock pin mechanisms 50 provided on the upper frame member F2.

6 and 7, reference numeral 10d is a pressing member pivotally supported by the upper frame member F2. The end portion 10d1 of the pressing member 10d is configured to contact the back surface of the line thermal head H. The end portion 10d1 of the pressing member can also serve as a heat dissipation member of the line thermal head H.

The lock pin mechanism 50 includes the platen roller 1 of the upper frame member F2 and the line thermal head H.
It is provided on both sides facing each other and is composed of a pin support portion 50a and a lock pin 50b. The pin support portion 50a is configured so that it can be manually bent left and right by a predetermined distance as shown by an arrow S in FIG. 6, whereby the lock pin 50b and the left and right end portions of the end portion 10d1 of the pressing member can be bent. It can be engaged and disengaged. The lock pin 50b is attached at a position where the line thermal head H can be pressed against the surface of the platen roller 1 with a predetermined pressure when engaged with the left and right ends of the end 10d1 of the pressing member. It

When setting the recording paper on the thermal printer P1d, first, the lock pin mechanism 50 is operated to release the engagement state between the lock pin 50b and the end portion 10d1 of the pressing member. Next, line thermal head H
The recording paper is inserted between the platen roller 1 and the platen roller 1, and the lock pin mechanism 50 is operated again to bring the lock pin 50b into engagement with the end portion 10d1 of the pressing member. Thereby, at the time of printing, an appropriate pressure can be applied to the recording paper nipped between the line thermal head H and the platen roller 1.

The position where the lock pin 50b is provided can be changed to the position indicated by a chain line 50c in FIG. In this case, the elasticity of the pressing member 10d can also be used to apply an appropriate pressure to the recording paper sandwiched between the line thermal head H and the platen roller 1.

Next, a thermal printer P1e according to the fourth embodiment will be described with reference to FIG.

In the thermal printer P1e, each member is attached to a frame F3 having a pair of side wall portions 900a and 900b and a thermal head support portion 901 provided between the side wall portions 900a and 900 with a predetermined inclination. Composed.

A motor M is arranged below one side wall 900a of the frame F3, and a drive gear g30 and a driven gear g40 are provided. Both side wall portions 900a, 90
At the upper end of 0b, a long groove 800 having an open part 800a on the upper side and a locking part 801 on the lower end side is formed.

Further, a line thermal head H is attached and provided on the upper surface of the thermal head support portion 901.

Each locking portion 801 of each long groove 800 is provided at a position where the surface of the platen roller 1 to be attached can be pressed against the line thermal head H in parallel to compress the platen roller. Further, in the figure, reference numeral 810 is a bearing member which is inserted into the tips of the rotary shafts 1A and 1B of the platen roller 1 and which is engaged with the locking portion 801 of the long groove 800.

Then, as shown in FIG. 8A, first,
A bearing member 810 is attached to the tip of the rotary shaft 1B of the platen roller 1.
Then, the rotary shafts 1A and 1B are inserted into the long groove 800 through the open portions 800a and 800b of the both long grooves 800.

Next, the surface of the platen roller 1 is held by being pressed by the line thermal head H (that is, a roller made of hard rubber or the like is slightly crushed and compressed), and the rotary shaft of the platen roller 1 is held. The bearing member 810 inserted through the tip portion of 1B is engaged with the locking portion 801 of the long groove 800 from the inside. Then, the bearing member 810 is engaged with the tip of the rotary shaft 1A of the platen roller 1 from the outside of the locking portion 801 of the long groove 800. Then, the driven gear g5
0 is attached to the tip of the rotary shaft 1A, and the driven gear g
60 is attached to the side wall 900a of the frame F3.

As described above, the pressing means (members such as coil springs) provided in the conventional printer can be eliminated to reduce the number of parts, and the printer can be downsized and the manufacturing cost can be reduced. . Further, since the work of incorporating a coil spring or the like is unnecessary, the assembling work can be simplified and the manufacturing cost can be further reduced.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the spirit of the invention.

For example, the pressing member (pressing portion) in the first to fourth embodiments can be designed to have a function as a heat radiating plate, and in this case, the pressing member has thermal conductivity and heat dissipation. It is more effective to use a metal such as zinc die cast, which has excellent properties.

In the present embodiment, the case where the frame F is made of a plastic injection molded product such as polycarbonate has been described, but the present invention is not limited to this, and a metal frame may be used. In particular, it is effective to use a metal having appropriate elasticity for the pressing portion 10a (10b) in the first embodiment. Further, it is effective to use a metal having an appropriate strength (hardness) for the pressing portion 10c in the second embodiment. Further, the pressing portions 10a to 10c are not limited to the case of being integrally formed with the frame (upper frame member F2), but include the case of being separate members.

In the first to third embodiments, the frame F is divided into the lower frame member F1 and the upper frame member F2.
Although the case where the structure is divided is described, the frame structure is not always essential in the present invention, and the frame structure may be any structure as long as it can press the line thermal head H against the platen roller 1. There is no limitation on the format or the like.

[0057]

As described above, the thermal printer according to the present invention includes a frame having a pair of side wall portions facing each other at a predetermined interval in the paper width direction, a line thermal head for printing, and A platen roller whose peripheral surface is in contact with the line thermal head, a pressing means for pressing the back surface of the line thermal head so that the line thermal head is pressed against the surface of the platen roller, and a motor as a drive source. And a gear transmission mechanism for transmitting the rotational driving force of the motor to the platen roller, the pressing means is a part of a constituent member of the frame pressed against the back surface of the line thermal head. Since it is configured, parts such as coil springs and other components provided in conventional printers are eliminated. It is possible to reduce the number, there is an effect that it is possible to cost reduction of the size and manufacturing cost of the printer.

Further, since the work of incorporating a coil spring or the like is not necessary, there is an effect that the assembling work can be simplified and the manufacturing cost can be further reduced.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a configuration of a thermal printer according to a first embodiment.

FIG. 2 is a perspective view showing the external appearance of the thermal printer according to the first embodiment.

FIG. 3 is a side sectional view showing a configuration of a thermal printer according to another example of the first embodiment.

FIG. 4 is a perspective view showing an appearance of a thermal printer according to a second embodiment.

FIG. 5 is a side sectional view showing a configuration of a thermal printer according to a second embodiment.

FIG. 6 is a perspective view showing the outer appearance of a thermal printer according to a third embodiment.

FIG. 7 is a side sectional view showing a schematic configuration of a thermal printer according to a third embodiment.

FIG. 8 is an exploded perspective view showing a configuration of a thermal printer according to a fourth embodiment.

FIG. 9 is a side sectional view showing a schematic configuration of the thermal printer according to the first embodiment.

FIG. 10 is an exploded perspective view showing a configuration of a conventional thermal printer.

[Explanation of symbols]

P1a, P1b, P1c, P1d, P1e Thermal printer F Frame F1 Lower frame member F2 Upper frame member 1 Platen roller H Thermal head M Motors 10a, 10b Pressing parts C1 to C4 Holding parts D1 to D4 Holding part G1 Gear transmission mechanism g1 , G2 Gear g20 Driven gear A Storage part B Gear storage part 50 Lock pin mechanism 50a Pin support part 50b Lock pin

[Procedure amendment]

[Submission date] October 15, 2002 (2002.10.
15)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

The lower frame member F1 is formed with an accommodating portion A for accommodating the platen roller 1, the thermal head H, the motor M as a drive source, and the like. Although not shown in the figure, the storage portion A is provided with a groove or a notch for positioning the thermal head H. Incidentally, the thermal head H, it is advisable to be attached to the heat radiating portion 11 described later of the upper side frame member F2. This allows
Assembling work can be performed more efficiently.
In addition, a support portion E3 for fixing the rear end portion of the motor M is formed in the storage portion A. Also, the thermal head H
Is provided with a connector 30 for connecting a signal line for transmitting a print signal.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

The position of the lock pin 50b can be changed to the position of the reference numeral 50c shown by the chain double- dashed line in FIG. In this case, the elasticity of the pressing member 10d can also be used to apply an appropriate pressure to the recording paper sandwiched between the line thermal head H and the platen roller 1.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction content]

Then, as shown in FIG. 8A, first,
A bearing member 810 is attached to the tip of the rotary shaft 1B of the platen roller 1.
Then, the rotary shafts 1A and 1B are inserted into the long groove 800 via the open portions 800a and 800a of the both long grooves 800.

Claims (6)

[Claims] 1. A frame having a pair of side wall portions facing each other at a predetermined interval in the paper width direction, a line thermal head for printing, and a platen whose peripheral surface is in contact with the line thermal head. A roller, a pressing unit that presses the back surface of the line thermal head so that the line thermal head is pressed against the surface of the platen roller, a motor as a drive source, and a rotational driving force of the motor is transmitted to the platen roller. In the thermal printer, the pressing means comprises a part of a constituent member of the frame that is pressed against the back surface of the line thermal head. 2. The frame is composed of a lower frame member and an upper frame member that can be divided into upper and lower parts, and a part of the constituent members of the frame constituting the pressing means is integrated with the upper frame member. A pressing portion having elasticity formed on the backside of the line thermal head when the upper frame member is fitted to the lower frame member. The thermal printer according to claim 1, wherein the thermal printer is formed at a position. 3. The frame is composed of a lower frame member and an upper frame member that are vertically separable, and a part of the constituent members of the frame that constitutes the pressing means is integrated with the upper frame member. Is a pressing portion having rigidity, and the pressing portion has an end portion of the pressing portion contacting the back surface of the line thermal head when the upper frame member is fitted to the lower frame member. The thermal printer according to claim 1, wherein the thermal printer is formed at a position. 4. The thermal printer according to claim 2, wherein the end portion of the pressing portion also serves as a heat radiating portion that conducts heat of the line thermal head and releases the heat. 5. A frame having a pair of side wall portions facing each other at a predetermined interval in the paper width direction, a line thermal head for printing, and a platen whose peripheral surface is in contact with the line thermal head. A roller, a pressing means for pressing the platen roller so that the line thermal head is pressed against the surface of the platen roller, a motor as a drive source, and a gear transmission for transmitting the rotational driving force of the motor to the platen roller. In a thermal printer including at least a mechanism, the pressing unit rotatably supports both ends of a rotation shaft of the platen roller so as to press the surface of the platen roller in parallel with the line thermal head to compress the surface. A thermal printer comprising a support member. 6. The support member includes a long groove formed on both side wall portions of the frame, having an open portion at an upper portion, and having a locking portion at a lower end side located near the line thermal head, And a bearing member that rotatably holds the rotating shaft of the platen roller that is inserted into the long groove through the opening of the long groove and that is engaged with the locking portion of the long groove. The thermal printer according to claim 5, wherein the stop portion is provided at a position where the surface of the platen roller is pressed in parallel with the line thermal head to compress the platen roller.