JPH0733103B2 - Thermal head - Google Patents

Description

TECHNICAL FIELD The present invention relates to a thermal head, and more particularly to a thermal head characterized by an arrangement of heating resistors.

(B) Conventional Technology As shown in FIG. 4, a conventionally well-known thermal head has a plurality of heating resistors 12 _-1 , 12 _-2 , ..., 12 arranged in a line on a substrate 11 made of ceramic or the like. _-8 are arranged, and further, a common electrode pattern conductor 13 commonly connected to each of the plurality of heating resistors 12 _-1 , 12 _-2 , ..., 12 _-8 , and each of the heating resistors 12 _-1 , 12 _-2, ..., 12 _-8 of the individual electrode pattern conductors 14 _-1 which are individually connected to each of 14 _-2, ..., in which 14 _-8 is formed.

(C) Problems to be solved by the invention Since the area (dot area) and the gap (interval) of each heating resistor of the conventional thermal head are uniform,
Ends as the surface temperature of the heating resistor string is low, since the central temperature is high, as shown in FIG. 3, during the printing operation, the heating resistor 12 _-1 at both ends, the print dots 16 corresponding to the 12 _{2 - 1} , 16 _-2
However, there was a problem that it was smaller than the central portion and the gap between the dots 16 _-1 and 16 _-2 was large.

In view of the above, the present invention makes the printing dot area by each heating resistor of the heating resistor array in which a plurality of heating resistors are arranged uniform, and the dot interval does not occur, or the dot interval becomes minute and uniform. The purpose is to provide a thermal head.

(D) Means and Actions for Solving Problems In order to solve the above problems, the thermal head according to the present invention has a plurality of heating resistors arranged on a substrate in a row at intervals. In a thermal head having a body row and a common electrode and an individual electrode for energizing each of the heat generation resistors, at least several heat generation resistors are arranged from both ends of the heat generation resistor row toward the center. The width is gradually reduced, and the distance between the heating resistors is increased toward the central portion side.

In this thermal head, the area (width) of the heating resistor is larger as it goes to both ends from the central part of the heating resistor row, and the interval is smaller on the contrary, so the temperature becomes lower toward both ends at the same area and at the same interval. Therefore, it is corrected that the print dot area becomes small, and each print dot becomes uniform.

(E) Examples Hereinafter, the present invention will be described in more detail with reference to Examples.

FIG. 1 is a plan view of a thermal head showing an embodiment of the present invention.

In this example thermal head, a plurality of heat generating resistors 2 _-1 , 2 _-2 , ..., 2 _-8 are arranged on a substrate 1, and these heat generating units 2 _-1 , 2 _-1 ,
2 _-2 , ..., 2 _-8 has a common electrode conductor pattern 3 at one end,
At the other end, individual electrode conductor patterns 4 _-1 , 4 _-2 , ..., 4
_-8 is formed, and in this basic structure, it is the same as the conventional one shown in FIG.

The thermal head of this embodiment is characterized by a heating resistor pattern for each dot of each heating resistor. That is, the width of the heating resistors 2 _-1 , 2 _-8 at both ends is the largest, and the width of the second heating resistors 2 _-2 , 2 _-7 from both ends is the heating resistors 2 at both ends.
_-1 , 2 _-8 width less than the width of the heating resistor inside 2
The width of _-3 , ..., 2 _-6 is set smaller than that of the second heating resistors 2 _-2 , 2 _-7 . And the space between each heating resistor
As for the size of 5a, 5b, 5c, ..., 5g, the outermost distances 5a, 5g closest to both ends are the narrowest, and the second distances 5b, 5f are next narrower than the inner ends, that is, both ends. Width of 5
It is made slightly wider than a and 5b, and the intervals 5c, 5d and 5e inside these second intervals 5b and 5f are made wider than the second interval. However, each heating resistor 2 _-1 , 2 _-2 ,
… The pitch of the center of 2 _-8 is made to be the same.

When a printing operation is performed using the thermal head of this embodiment,
As shown in Fig. ₂ , the print dots 6 _-1 , 6 _-2 formed by the heating resistors 2 _-1 , 2 _{-2 having} a large width cover the low temperature because they are the end portions by the area size. Print dot 6 in the center
_-3 , 6 _-4 , 6 _-5 , ... Approximately the same size, and since the distances 5a, 5b at the ends are narrower than the distances 5c, 5d, 5e at the center, the print dots are small. Printing dots that cover the entire surface and are uniform as a whole, and that are adjacent to each other
You can get 6 _-1 , 6 _-2 , 6 _-3 , ... Although FIG. 2 shows only one end of the heating resistor array, the same can be said for the other end symmetrically.

Although the number of heating resistors is eight in the above embodiment, the present invention is not limited to this number.

Further, in the embodiment, the two intervals from both ends are made narrower than the interval in the central part and further toward the outer side. However, in a thermal head having a large number of heating resistors, this It goes without saying that the interval width can be changed from the both ends to the inside, and the number can be increased to three or more.

(F) Effect of the Invention According to the present invention, in a thermal head in which a plurality of heating resistors are arranged in a line at intervals, the width of at least several heating resistors is sequentially arranged from both ends toward the center. Since it is made small and the gap is made large, the energy applied to the heating resistor array becomes large at both ends, it is possible to prevent thinning of the print at both ends, and obtain a substantially uniform printed dot. be able to. Further, since the print interval at both ends is narrowed, the print dot gap at both ends, which has conventionally occurred, can be reduced, and the print quality is improved.

[Brief description of drawings]

FIG. 1 is a plan view of a thermal head showing an embodiment of the present invention, FIG. 2 is a view for explaining the operation of the thermal head of the same embodiment, and FIG. 3 is for explaining the operation of a conventional thermal head. 4 and 5 are plan views showing a conventional thermal head. 1: Substrate, 2 _-1・ 2 _-2 ...... 2 _-8 : Heating resistor, 3: Common electrode conductor pattern, 4 _-1・ 4 _-2 ...... 4 _-8 : Individual electrode conductor pattern, 5a ・ 5b ・5c ... 5g: Interval.

Claims (1)

[Claims] 1. A heating resistor array in which a plurality of heating resistors are arranged in a row at intervals with each other, and a common electrode and an individual electrode for energizing each of the heating resistors are formed on a substrate. In the thermal head, the width of at least several heating resistors is gradually reduced toward the center from both ends of the heating resistor row in the previous term, and the spacing between the heating resistors becomes larger toward the central part. The thermal head is characterized by doing so.