JP3107196B2 - Thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a thermal head.

[0002]

2. Description of the Related Art The structure of a conventional general thermal head is shown in FIG. 2A is a plan view of the wiring pattern, and FIG. 2B is a cross-sectional view taken along a line BB of FIG. 2A. As shown in FIG. 2, the thermal head 10 includes a glaze layer 12 provided on an upper surface of a ceramic substrate 11.
A common electrode 14 formed substantially parallel to the heating resistor 13 extending in the longitudinal direction;
And a separate electrode 16 for connecting each print dot unit of the heating resistor 13 to a drive IC (not shown).

In the thermal head 10 provided with the wiring patterns of the respective electrodes, if the wiring distance of the common electrode 14 becomes longer, a voltage drop in the longitudinal direction becomes a problem, and a driving current flows from both ends of the common electrode 14. In this case, since the voltage applied to each heating dot becomes lower toward the center in the longitudinal direction, a density difference occurs in the recording result. Therefore, in order to reduce the resistance value of the common electrode 14 in the longitudinal direction, the common electrode 1
Reference numeral 4 denotes a two-layer structure in which the entire surface of a silver wiring pattern 14b is laminated as an upper layer of a lower wiring pattern 14a of gold, and the voltage drop is reduced by the upper wiring pattern 14b of silver.

[0004]

However, the common electrode 1
Even if the wiring pattern 4 has a two-layer structure, the wiring pattern 14b made of silver in the upper layer must be formed thick in order to reduce the resistance value as the wiring pattern area is reduced. But,
In the case where the wiring pattern 14b made of silver in the upper layer is formed thick, if the thickness per printing is increased, peeling or foaming after sintering may cause printing defects.

Further, the wiring pattern 1 made of silver in the upper layer is used.
Since the entire surface of the wiring pattern 4b is laminated on the lower wiring pattern 14a made of gold, there is a problem in that the adhesion is weak, and since the lamination is made of dissimilar metals, they are mutually diffused to lower the electric conductivity. An object of the present invention is to provide a thermal head capable of solving the above-mentioned problems and suppressing the occurrence of printing defects.

[0006]

According to the thermal head of the present invention, a heating resistor and a common electrode of the heating resistor are formed on an upper surface of an insulating substrate so as to extend substantially in parallel, and the common electrode is formed of a lower layer of gold. In a thermal head having a two-layer structure of a wiring pattern and an upper silver wiring pattern, slits are formed at a predetermined pitch in the width direction of the lower gold wiring pattern, and the width of the upper silver wiring pattern (W ) Is made shorter than the length (L) of the slits, and the wiring pattern made of silver in the upper layer is laminated so as to completely overlap with all the slits. As a result, the upper wiring pattern made of silver alternately comes into contact with the lower wiring pattern made of gold and the insulating substrate, thereby improving the adhesion between the two wiring patterns.

[0007]

FIG. 1 shows an embodiment of a thermal head according to the present invention. FIG. 1 (A) is a plan view of a wiring pattern, and FIG. 1 (B) is a plan view of FIG. 1 (A). It is AA sectional drawing. As shown in FIG. 1, a thermal head 1 has a two-layered common electrode formed on a glaze layer 3 provided on an upper surface of a ceramic substrate 2 and substantially in parallel with a heating resistor 4 extending in the longitudinal direction thereof. 5, a comb-shaped electrode 6 extending from the common electrode 5 to each printing dot of the heating resistor 4, and an individual electrode 7 for connecting each printing dot unit in the heating resistor 4 to a driving IC (not shown). It has.

The wiring pattern of the common electrode 5 has a two-layer structure of a lower wiring pattern 5a made of gold and an upper wiring pattern 5b made of silver, and the lower wiring pattern 5a made of gold has an upper end portion. Are formed at predetermined pitches in the longitudinal direction to form a comb-like wiring pattern.

A comb-shaped electrode 6 extending from the lower end of the lower wiring pattern 5a made of gold to the heating resistor 4 is formed. When laminating the upper silver wiring pattern 5b on the lower gold wiring pattern 5a having the wiring pattern, the width W of the upper silver wiring pattern 5b is made shorter than the length L of the slit 5c. hand,
Lamination is performed so that the upper silver wiring pattern 5b completely overlaps all the slits.

By using the common electrode 5 having such a two-layer structure of the wiring pattern, the entire surface of the upper wiring pattern 5b made of silver alternately contacts the lower wiring pattern 5a made of gold and the glaze layer 3; The adhesion between the wiring pattern 5b and the wiring pattern 5a made of silver in the upper layer can be improved, and peeling and foaming of the wiring pattern 5b made of silver in the upper layer can be prevented.

Further, since mutual diffusion between both metals constituting the wiring pattern can be reduced, a decrease in electric conductivity can be prevented. In addition, when the upper wiring pattern is applied thicker, the gas generated from the lower wiring pattern increases the thickness of the upper wiring pattern per printing because pinholes are generated in the upper wiring pattern. However, when the wiring pattern is used, the wiring pattern 5b made of silver in the upper layer is used.
Can be made thicker per printing.

[0012]

According to the thermal head using the common electrode of the wiring pattern of the present invention, the adhesive strength of the common electrode is improved and the printing density difference can be reduced over the entire length of the heating resistor.

[Brief description of the drawings]

FIG. 1 is a plan view and a sectional view of a main part of an embodiment of a thermal head according to the present invention.

FIG. 2 is a plan view and a sectional view of a main part of a conventional thermal head.

[Explanation of symbols]

 4. Heating resistor 5. Common electrode of two-layer structure 5a. Wiring pattern of lower gold 5b. Wiring pattern of upper silver

Claims (1)

(57) [Claims] 1. A heating resistor and a heating resistor on an upper surface of an insulating substrate.
The common electrode of the antibody is formed so as to extend substantially in parallel,
The common electrode is made of a lower gold wiring pattern and an upper silver
Thermal head with a two-layer structure
A predetermined pitch in the width direction of the wiring pattern of the lower layer of gold.
And a wiring pattern made of silver in the upper layer.
Width (W) is shorter than the length (L) of the slit.
The wiring pattern made of silver in the upper layer is all the slits.
Characterized in that it is laminated so as to completely overlap
Head.