JPH04234685A - Thermal printer - Google Patents

Abstract

PURPOSE:To provide a thermal printer in line dot type wherein printing is mode by line feeding, especially in such type wherein a thermal head is so constructed that it can be pressed against printing paper, and is equipped with an automatic pressure regulating mechanism and is made easily constructible with parts easily machined and is further made easily adjastable. CONSTITUTION:A head support section 6 is composed of a fixed shaft 61 that is placed in parallel with the shaft of a platen 1, a head support plate 63 having a guide plate 62 that comes at least in contact with the fixed shaft 61, a support shaft 64 fixed to the center of the guide plate 62 intersecting at a right angle the fixed shaft 61, and a guide piece 65 that is fixed to the front end of the support shaft 64 with the fixed shaft 61 interposed between the said guide piece and the guide plate 62, and is so constructed that a thermal head supported therewith is pressed against printing paper 2 by at least one helical tension spring 8 that is placed between a frame 7 and the guide piece 65.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line-dot type thermal printer that prints one line at a time, and more particularly to the structure of a head support unit that presses a thermal head against printing paper.

A line dot type thermal printer has a rubber roller-like platen that supports printing paper from the back, and
Printing that is driven and fed via the platen has a thermal head formed of a plurality of resistance heating elements arranged parallel to the axis of the platen, and a head support unit that presses the thermal head against the printing paper with an appropriate force. Each line is printed on the paper.

However, if the force with which the thermal head is pressed against the printing paper differs between the right and left ends of the head support section, the print density will be higher in the area where the force of pressing the thermal head against the printing paper is stronger, but the force with which the thermal head is pressed against the printing paper is weaker. In some areas, the print density becomes thinner and the print quality deteriorates significantly. Therefore, there is a need for the development of a head support unit that presses the thermal head against the printing paper with a uniform force.

0004

2. Description of the Related Art FIG. 5 is a perspective view showing the main parts of a conventional thermal printer. In the figure, in a conventional thermal printer, both ends of a shaft 11 are held by bearings (not shown), a rubber roller-shaped platen 1 that feeds printing paper 2 and supports it from the back, and a plurality of resistance heating elements 31 are arranged parallel to the platen 1. The thermal heads 3 arranged in an array, the head support section 4 in which a rotating shaft 41 provided at one end is held by a bearing (not shown), and the thermal head 3 fixed to the head support section 4 are pressed against the printing paper 2. It is equipped with a leaf spring 5.

[0005]

[Problems to be Solved by the Invention] However, in order to press the thermal head against the printing paper with a uniform force in a conventional thermal printer, it is necessary to hold the platen and the head support part by bearings so that their rotational axes are parallel to each other, and The surface of the thermal head on which the resistive heating element is formed must be parallel to the rotation axes of the platen and head support. Therefore, there is a problem in that each component must be formed with high precision.

[0006] An object of the present invention is to provide a thermal printer which has an automatic pressure regulating mechanism and is easy to process, assemble, and adjust parts.

[0007]

[Means for Solving the Problems] FIG. 1 is a perspective view showing an embodiment of a thermal printer according to the present invention. The same objects are represented by the same symbols throughout the figures.

The above problem is solved by a rubber roller-shaped platen 1 that holds both ends of a shaft 11 and supports printing paper 2 from the back side;
It has a thermal head 3 in which a plurality of resistance heating elements 31 are arranged parallel to the axis of the platen 1, and a head support part 6 that presses the thermal head 3 against the printing paper 2 with an appropriate force, and prints while feeding the printing paper 2. This is a line-dot type thermal printer that performs
a head support plate 63 having a fixed shaft 61 parallel to the axis of the fixed shaft 61; a head support plate 63 having a guide plate 62 that contacts at least the fixed shaft 61; a support shaft 64 fixed to the center of the guide plate 62 and perpendicular to the fixed shaft 61; It has a guide piece 65 fixed to the tip of the frame 7 and sandwiching the fixed shaft 61 between it and the guide plate 62.
This is achieved in the thermal printer of the present invention in which the thermal head 3 is pressed against the printing paper 2 by at least one tension coil spring 8 mounted between the guide piece 65 and the guide piece 65 .

[0009]

[Operation] In FIG. 1, the head support part has a fixed shaft parallel to the axis of the platen, a head support plate having at least a guide plate that abuts the fixed shaft, and a support shaft fixed at the center of the guide plate and perpendicular to the fixed shaft. , has a guide piece fixed to the tip of the support shaft and sandwiching the fixed shaft between it and the guide plate, and at least one tension coil spring installed between the frame and the guide piece causes the thermal head to touch the printing paper. In the pressed thermal printer of the present invention, the head support plate can rotate around the fixed shaft and the support shaft. Closely attached to the sides, the pressure difference between both ends of the thermal head is automatically adjusted. That is,
It is possible to realize a thermal printer that has an automatic pressure adjustment mechanism and is easy to process, assemble, and adjust parts.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a side sectional view showing another embodiment of the invention, FIG. 3 is a side sectional view showing still another embodiment of the invention, and FIG. 4 is a side sectional view showing a modification of the thermal printer according to the invention. It is.

In FIG. 1, the thermal printer according to the present invention has a shaft 11 held at both ends by bearings (not shown), a rubber roller-shaped platen 1 that feeds the printing paper 2 and supports it from the back, and a plurality of resistance heating elements 31. The thermal head 3 is arranged parallel to the platen 1, and a head support part 6 presses the thermal head 3 against the printing paper 2 with an appropriate force.

The head support portion 6 includes a fixed shaft 61 that is fixed to a frame (not shown) and is parallel to the axis of the platen 1, and a guide plate 6 that is bent at a right angle at one end and abuts the fixed shaft 61.
2 is formed, one support shaft 64 is fixed to the center of the guide plate 62 and perpendicular to the fixed shaft 61, and a fixed shaft is fixed to the tip of the support shaft 64 and between the guide plate 62. A guide piece 65 is provided to sandwich the guide piece 61.

One tension coil spring 8 is installed between the frame 7 of the thermal printer and the center of the guide plate 62, and this tension coil spring 8 rotates the head support plate 63 about the fixed shaft 61 as a fulcrum. The thermal head 3 fixed to the other end of the head support plate 63 is pressed against the printing paper 2.

In another embodiment of the thermal printer according to the present invention shown in FIG. 2, the frame 7 and the guide plate 6
2, one tension coil spring 8 is mounted between the frame 7 and the center of the guide piece 65, and this tension coil spring 8 is attached to the fixed shaft 61. The head support plate 63 is rotated using the head support plate 63 as a fulcrum, and the thermal head 3 fixed to the other end of the head support plate 63 is pressed against the printing paper 2.

In still another embodiment of the thermal printer according to the present invention shown in FIG. 3, the frame 7 and the guide plate 6
2, one compression coil spring 9 is attached between the frame 7 and the center of the head support plate 63, and the compression coil spring 9 is attached to the fixed shaft 61. The head support plate 63 is rotated using the head support plate 63 as a fulcrum, and the thermal head 3 fixed to the other end of the head support plate 63 is pressed against the printing paper 2.

In addition, in FIG. 1, the frame 7 and the guide plate 62
One tension coil spring 8 is installed between the center of the frame 7 and the center of the head support plate 63 in FIG. 3, and one compression coil spring 9 is installed between the frame 7 and the center of the head support plate 63 in FIG. Two tension coil springs 8 may be installed between the frame 7 and both sides of the guide plate 62, and two compression coil springs 9 may be installed between the frame 7 and both sides of the head support plate 63 in FIG.

The head support plate 63 to which the thermal head 3 is fixed can rotate about the support shaft 64 as a fulcrum. For example, even if the axis of the platen 1 and the fixed shaft 61 are not parallel, the thermal head 3 can be rotated. is in close contact with the side surface of the platen 1, and the pressure difference between both ends of the thermal head 3 is automatically adjusted. In other words, it has an automatic pressure regulation mechanism and is suitable for parts processing and assembly.
A thermal printer that is easy to adjust can be realized.

A modification of the thermal printer according to the present invention is as shown in FIG.
, the support shaft 64, and the guide piece 65, the head support part 6 includes a head support plate 67 having a U-shaped cross section with a through hole 66 in the center, and a short shaft provided perpendicularly to the center of the long axis 68a. 68b is composed of a T-shaped shaft 68 passing through the through hole 66, and is fixed to the other end of the head support plate 67 by a tension coil spring 8 installed between the frame 7 and the center of the head support plate 67. The thermal head 3 is pressed against the printing paper 2.

The head support plate 67 to which the thermal head 3 is fixed can rotate about the short axis 68b as a fulcrum, and even if the axis of the platen 1 and the long axis 68a are not parallel, for example, the thermal head 3 can be rotated. is in close contact with the side surface of the platen 1, and the pressure difference between both ends of the thermal head 3 is automatically adjusted. That is, it is possible to realize a thermal printer that has an automatic pressure regulating mechanism and is easy to process, assemble, and adjust parts.

[0020]

As described above, according to the present invention, it is possible to provide a thermal printer which has an automatic pressure regulating mechanism and is easy to process, assemble, and adjust parts.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a thermal printer according to the present invention.

FIG. 2 is a side sectional view showing another embodiment of the present invention.

FIG. 3 is a side sectional view showing still another embodiment of the present invention.

FIG. 4 is a side sectional view showing a modification of the thermal printer according to the present invention.

FIG. 5 is a perspective view showing the main parts of a conventional thermal printer.

[Explanation of symbols]

Claims (4)

[Claims] Claim 1: A rubber roller-shaped platen (1) that holds both ends of the shaft (11) and supports the printing paper (2) from the back side.
1) and a plurality of resistance heating elements (31) are connected to the platen (
1) Thermal head (3) arranged parallel to the axis of
It is a line-dot type thermal printer that has a head support part (6) that presses the thermal head (3) against the printing paper (2) with an appropriate force, and prints while feeding the printing paper (2). There, the head support part (6
) is a fixed axis (61) parallel to the axis of the platen (1).
and a guide plate (
a head support plate (63) having a guide plate (62);
The fixed shaft (61) is fixed between a support shaft (64) fixed at the center of the support shaft (62) and orthogonal to the fixed shaft (61), and a support shaft (64) fixed at the tip of the support shaft (64) and the guide plate (62). It has a guide piece (65) that sandwiches the frame (7) and the guide plate (
A thermal printer characterized in that the thermal head (3) is pressed against the printing paper (2) by at least one tension coil spring (8) mounted between the thermal head (3) and the printing paper (2). 2. A tension coil spring (8) installed between the frame (7) and the guide plate (62) according to claim 1.
) instead of at least one tension coil spring (8) mounted between the frame (7) and the guide piece (65).
), the thermal head (3) moves the printing paper (2
) A thermal printer characterized by being pressed against. 3. A tension coil spring (8) installed between the frame (7) and the guide plate (62) according to claim 1.
), replace it with the frame (7) and head support plate (63).
A thermal printer characterized in that a thermal head (3) is pressed against a printing paper (2) by at least one compression coil spring (9) mounted between the thermal head (3) and the printing paper (2). 4. The fixed shaft (61), the head support plate (63), the support shaft (64), and the guide piece (
65), the head support part (6) is a head support plate (67) having a U-shaped cross section and having a through hole (66) in the center.
and a short axis (68a) perpendicular to the center of the long axis (68a).
A T-shaped shaft (68b) passes through the through hole (66).
and at least one tension coil spring (8) installed between the frame (7) and the head support plate (67), the thermal head (3) is attached to the printing paper (2). ) A thermal printer characterized by being pressed against.