JPS60104348A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain uniform printing (recording) even to recording paper having any surface state, by allowing a heat generating resistor to follow the unevenness of recording paper. CONSTITUTION:Heat generating resistor layers 13 are formed to the upper surfaces of the strip like elastic heat insulating members 6 secured onto a ceramic substrate 11 and the same number of conductive pattern layers 14 as the heat generating resistors are further formed onto said resistor layers 13. In this case, each of the conductive pattern layers 14 is removed at a part corresponding to each elastic heat insulating members 6 and the part of the heat generating resistor layer not covered by each conductive pattern layer comes to a heat generating resistor 13'. By this method, heat generating resistors 13' are arranged in one line in the longitudinal direction of a thermal head so as to be uniformly protruded from the standard surface of the substrate 11 and protective layers 15 are uniformly formed to the upper surfaces of the conductive layers. Because the elastic heat insulating members 6 having the heat generating resistors held to the upper surface thereof has elasticity, the heat generating resistor layer 13 shows good following property to the surface unevenness of recording paper.

Description

[Detailed description of the invention] (Technical field) The present invention relates to the structure of a thermal head.

(Prior art) As shown in FIGS. 1(a) and 1(b), a conventional thermal head has a heat insulating layer 2 provided on a ceramic substrate 1, and a plurality of heating resistors 6, an electrode layer 4, and a heat insulating layer 2 on top of the heat insulating layer 2. It is formed by laminating layer 5. Here, the role of heat insulation (eat 2) is to transfer the heat generated by the heating resistor 6 to the ceramic substrate 1 during printing.
In addition to efficiently transmitting heat to the thermal recording paper that is in contact with the surface of the thermal head without letting it escape to the side, the excess heat accumulated during long-term continuous printing is gradually released to the ceramic substrate 1filI. The purpose is to suppress the temperature rise of the heating resistor B.

For example, when a conventional thermal head with this type of structure prints by pressing against thermal recording paper, the heating resistor 3 is fixed to the substrate 1, so it is difficult to follow the unevenness of the recording paper surface. 1'ifi was not possible, which caused uneven print density.

(Purpose) The present invention has been made in order to solve the above problems, and its purpose is to cause the heating resistor to move minutely to follow the unevenness of the recording paper, and to eliminate the unevenness on the surface of the recording paper. The object of the present invention is to eliminate variations in printing (recording) density due to the following.The present invention will be explained below based on drawings of embodiments.

(First Embodiment) Figures 2112 (a) and (b) show a thermal head 10 that is a first embodiment of the present invention. First, a band-shaped elastic heat-retaining portion 6 made of heat-resistant rubber or heat-resistant synthetic resin is fixed onto the flat ceramic substrate 11, which has high heat resistance, heat retention, and elasticity. A heat generating resistor layer 16 is formed on the upper surface of this elastic heat insulating member B by sputtering or the like, and furthermore, on the upper surface of this heat generating resistor layer 16,
The number of conductive pattern layers 14 is equal to the number of heating resistors.

The portion of the conductive pattern layer 14 corresponding to the elastic heat retaining portion 6 is removed as shown in the figure, and the portion of the heating resistor layer that is not covered with the electrocardiogram pattern layer becomes the heating resistor 13.
' becomes. The plural heating resistors 16' thus formed are arranged in a line in the longitudinal direction of the thermal head 10, and each heating resistor 16' uniformly protrudes from the reference surface of the substrate 11. A protective layer 15 is uniformly formed on the upper surface of the insulation layer. Therefore, on the surface of F415 (protected), the position corresponding to the heating resistor 16' protrudes compared to other positions, and as shown in the examples shown in Fig. 1(a) and (b), the position corresponding to the heating resistor 16' is In this embodiment, the elastic heat retaining part 6 that holds the heat generating resistor 16' on its upper surface is It has elasticity. For this reason, when the thermal head 10 is pressed against the thermal recording paper or the ink ribbon is pressed against the advancing recording paper, the heating resistor 16' retreats into the unevenness of the recording paper surface, and the heating resistor 16' retreats in the thickness direction of the substrate 11. The heat generating resistor moves slightly, and air gaps are less likely to be formed between the surface of the recording paper and the heating resistor. In addition, each heating resistor 16
' move slightly individually, so that it follows the unevenness of the recording paper better, and even printing (recording) can be performed.

(Second Embodiment) FIG. 6 shows a thermal head 20 according to a second embodiment of the present invention.
In this example, the minute movement of the heating resistor 16' in the Jv direction of the ceramic substrate 21 is achieved by providing the substrate 21 with a slit 22.

The back surface of the substrate 21 is cut out at the position where the heating resistor 16' is formed to form four parts 21a.

Furthermore, a plurality of slits 22 are formed in this recess 21a so as to partition each heating resistor. Board 2
The heat generating resistor holding portions 21b which are held between the slits 22 of 1 and which hold the heat generating resistors are thin and made of ceramic material, but they undergo minute elastic displacement and hold the heat generating resistors. 16' is moved in the thickness direction of the substrate 21.

The slit 22 and the four parts 21a are integrally formed when the substrate 21 is molded using a mold, but the slit 22 may be formed later using a laser cutter or the like. In any case, for the substrate 21 having the four parts 21a and the slits 22 as described above, all parts (the elastic heat retaining part 6, the heating resistance layer, the conductive pattern layer, the protective layer, etc.) of the first embodiment are applied. The heating resistor 16' is formed.

As described above, when the purchased thermal head 20 is pressed against the recording paper, each heating resistor holding portion 21b bends following the unevenness of the recording paper, and the heating resistors 16' and the recording paper surface are bent. Eliminate the air gap.

Further, in this example, the elastic heat retaining member 6 also functions in the same manner as in the first example, and the gap between each heating resistor and the unevenness of the recording paper is further reduced. Printing unevenness does not occur when printing (recording) with a secondary paper.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be applied to, for example, a thermal head equipped with multiple rows of heating resistors or a so-called full multi-type thermal head. According to the present invention, uniform printing (recording) can be obtained on recording paper of any surface condition, which is extremely useful.

[Brief explanation of the drawing]

Figures 1 (a) and (b) show the outside of the conventional thermal head.
Figures and partial views, ε(!2 Figures (a) and (b) are external views of the thermal head according to the 2141st embodiment of the present invention, ), (bl is a front side external view and a 292 Tsukuda external view of a thermal head according to a second embodiment of the present invention. 10, 20, 11-Thermal head

Claims (2)

[Claims] (1) A thermal head having a plurality of heating resistors on a substrate, characterized in that the substrate is provided with means for holding the heating resistors movably in the thickness direction of the substrate. (2) Claim 1, characterized in that the means is a slit, characterized in that it is an elastic retaining member provided on the substrate. thermal head.