JPS6342579B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal printing head, and more particularly to a thermal printing head in which a heating element is formed of a thick film.

In a thermal printing head, in order to improve the printing quality, it is sufficient to narrow the distance between the colored dots printed on the thermal paper, and for this purpose, it is necessary to make the distance between the heat-generating dots sufficiently small. As an example of a structure for narrowing the interval between heating dots, the one shown in FIGS. 1 and 2 is used. In the figure, 1 is an insulating substrate, 2 is a conductor of a current carrying body, and 3 is a heating element. The conductors 2 are formed parallel to each other, and a heating element 3 is formed so as to straddle each pair of adjacent conductors 2. The heating element 3 is formed of a thick film. That is, it is formed by screen printing a resistive paste and firing it. According to this, the heating element portion that generates heat by applying a voltage between adjacent conductors acts as one heating dot, so that the distance between adjacent conductors becomes sufficiently narrow, which is convenient.

By the way, when screen printing resistor paste, make the width narrower (for example, about 0.3 mm).
It is known that when printed in a raised manner, the top surface becomes half-sided as shown in FIG. This is thought to be due to the fluidity and surface tension of the resistance paste. When the top surface of the heating element is semicircular in this way, only the vicinity of the top surface comes into contact with the thermal paper, and the area of the coloring dots is not as large as the surface area of the heating dots. Therefore, even if the spacing between the heat-generating dots is made narrow enough, unless the heat-generating dots are flat, the spacing between the colored dots will not become narrow enough, and no significant improvement in printing quality can be expected.

The object of the present invention is to make the area of the coloring dots almost the same as that of the heating dots even when the spacing between the heating dots is narrowed, so that the spacing between the coloring dots can be sufficiently narrowed.

In this invention, an insulator is formed extending in a direction perpendicular to the conductors between a plurality of pairs of current-carrying conductors, sandwiching a region where a heat generating resistor is formed, and connecting the insulators with each other. It is characterized by forming a thick film heating element filled with resistance paste.

An embodiment of the present invention will be explained with reference to FIGS. 3 and 4. Reference numeral 11 is an insulating and heat-resistant substrate such as ceramic, and 12 is a plurality of current-carrying substrates formed parallel to each other. The conductor 13 is a heating element made of a resistance paste formed between the pair of conductors, and the numerals 14 and 15 are insulators formed on both sides of the heating element 13. The insulators 14 and 15 are the heating element 1
3 is formed in advance. This formation location is located on both sides of the region where the heating element 13 is formed. After forming the heating element 13 in this way, a resistance paste for the insulators 14 and 15 is screen printed between the two insulators 14 and 15, and the area where it is formed is partitioned by the insulators 14 and 15. Since the surface is covered, press firmly against the surface.
Screen printing can be performed to fill the space between the insulators 14 and 15, thereby making the surface of the heating element 13 substantially flush with the surfaces of the insulators 14 and 15. Therefore, when thermal printing is performed by pressing this onto thermal paper, one dot of the heating element 13, that is, the entire area of the heating element divided by both insulators 14 and 15 and a pair of adjacent conductors 12 is printed. Since the surface comes into contact with the thermal paper, it is possible to avoid the area of one color-developing dot from being less than the surface area of one heat-generating dot. Since the interval between each heat generating dot is originally formed sufficiently narrow, the interval between coloring dots also becomes sufficiently narrow, so that printing quality can be far improved compared to the conventional method.

Also, as mentioned above, since the entire surface of the heating element 13 is in contact with the thermal paper, if the width of each heating dot is the same, the heating element 13 will generate less heat compared to the case where a semicylindrical heating element as shown in Fig. 2 is used. This means that the width of the body needs to be sufficiently narrow, and a smaller heating element is sufficient. Therefore, the apparent power consumption required to generate heat to a predetermined temperature can be reduced.

By making the surfaces of the insulators 14 and 15 and the heating element 13 flat and coplanar, the thermal paper etc. can be applied not only to the flat surfaces of the heating element 13 but also to the surfaces of the insulators 14 and 15. Since the contact can be made uniformly, the contact pressure per unit area is reduced, and since the paper surface does not come into contact with the end of the heating element 13, the frictional force is reduced.

5 to 10 show an example of the manufacturing process of the thermal printing head shown in FIG. 3. First, a plurality of conductors 12 are formed on the surface of a substrate 11. This is manufactured by screen printing a conductive paste and firing it (see FIGS. 5 and 8). Next, insulators 14 and 15 are formed so as to extend in a direction across each conductor 12. This is also manufactured by screen printing an insulating paste and firing it (see Figures 6 and 9). Then, a heating element 13 is formed in a region surrounded by insulators 14 and 15. This is also manufactured by screen printing a resistive paste and firing it. In this way, the thermal printing head shown in FIGS. 3 and 4 is completed. In addition, when it is necessary to protect the surface of the heating element 13, a protective paste is screen printed on the surface and baked.
A protective film 16 may be formed as shown in FIG.

The above embodiment is an example in which the present invention is applied to a structure in which the spaces between the heating dots are narrowed, with the heating dots formed between the adjacent conductors of the conductors arranged in parallel with each other. The figures and subsequent figures show an example in which the present invention is applied to a configuration in which instead of this, heating dots are formed between conductors facing each other and the spacing between the heating dots is narrowed. According to this, a plurality of conductors 12A parallel to each other and a plurality of conductors 12B parallel to each other are formed on the surface of the substrate 11, and insulators 14 and 15 are placed between the conductors 12A and 12B. It is formed by extending in the direction perpendicular to the A heating element 13 is then formed between both insulators 14 and 15. The heating element 13 is formed astride conductors 12A and 12B that face each other.
Therefore, conductors 12A, 12B facing each other
This conductor 12 by applying a voltage between
The heating element part between A and 12B generates one heating dot. Even in this case, the interval between the heating dots can be made sufficiently narrow, and the surface of the heating element 13 can be formed almost flat due to the presence of the insulators 14 and 15, so that the surface area of the heating element 13 is smaller than that of one heating dot. There is no possibility that the area will become smaller than the area of one colored dot.

13 to 15 show an example of the manufacturing process of the thermal printing head shown in FIG. 11. First the board 11
A plurality of conductors 12A and 12B are formed parallel to each other on the surface of the conductors 12A and 12B, spaced apart from each other. This is manufactured by screen printing a conductive paste and firing it (Fig. 13, 1).
See figure 6. ). Next, insulators 14 and 15 are formed extending in a direction across each conductor 12A and 12B and separating the heating element formation region. This is also manufactured by screen printing an insulating paste and firing it (see FIGS. 14 and 17). Figures 6 and 7 below
It can be manufactured using the same process as shown in the figure.

As detailed above, according to the present invention, the surface of the heating element can be made substantially flat in a shape in which the interval between each heating dot is sufficiently narrowed, and therefore the interval between adjacent colored dots can be narrowed. This makes it possible to reliably improve printing quality, and even if the width of the colored dot is the same, it consumes less power than the conventional configuration. Also, a heating element,
Since the surface of the insulator is flat and coplanar, the contact pressure per unit area between the thermal paper and the heating element etc. is reduced, and the frictional force is also reduced.

[Brief explanation of the drawing]

Figure 1 is a plan view of the conventional example, Figure 2 is a sectional view of the same,
FIG. 3 is a plan view showing an embodiment of the present invention, FIG. 4 is a sectional view thereof, FIGS. 5 to 7 are plan views showing the manufacturing process, and FIGS. 7, FIG. 11 is a plan view showing another embodiment of the present invention, FIG. 12 is the same sectional view, FIGS. 13 to 15 are plan views showing the manufacturing process, and FIGS. 16 to 15. FIG. 18 is a sectional view of FIGS. 13 to 15. 11... Substrate, 12, 12A, 12B... Conductor, 13... Heating element, 14, 15... Insulator.

Claims (1)

[Claims] 1. In a thermal printing head in which a heating element is formed by firing on a plurality of parallel current-carrying conductors that form a pair with each other on a substrate, the printing head is placed in contact with the heating element, sandwiching the heating element, and is heated by firing. an insulator is formed, the surface of the insulator and the surface of the heating element are flat surfaces,
A thermal printing head characterized in that the heads are substantially coplanar.