JPH08108557A - Thermal head - Google Patents

Abstract

PURPOSE: To miniaturize the dimension of an outer diameter and to ensure the current capacity of a common electrode pattern by extending drawing-out patterns in the same direction as individual electrode patterns to connect them to the patterns parallel to the heating resistors provided to the lower parts of a plurality of drive ICs. CONSTITUTION: A plurality of drive ICs 5 are provided so as to be arranged on the drawing-out side of individual electrode patterns 4 in a row along heating resistors. Herein, drawing-out patterns 31 formed so as to have width larger than that of electrode patterns 3, 4 are respectively connected to some of a plurality of the electrode patterns 3, 4 and the drawing-out patterns 31 are respectively extended in the same direction as the drawing-out sides of the individual electrode patterns 4. The extended drawing-out patterns 31 are connected to the patterns 32 parallel to the heating resistors 2u provided to the lower parts of the drive ICs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head.

[0002]

2. Description of the Related Art In the thermal head shown in FIG. 3, a heating resistor film is provided on an upper surface of an insulating substrate 1 to form a heating resistor 2, and a common electrode pattern 3 and a common electrode pattern 3 are provided on both sides of a hem of the heating resistor 2. The individual electrode patterns 4 and the individual electrode patterns 4 are alternately arranged in a permutation. That is, the heating resistor 2 is arranged in parallel with and in parallel with one end of the insulating substrate 1, and the common electrode pattern 3 is located between the heating resistor 2 and one end of the insulating substrate 1. Both ends of this common electrode pattern 3 are formed in a planar U-shape so as to be parallel to the pattern direction of the individual electrode pattern 4.

FIG. 2 shows a thermal head according to a prior application of the present application. In this thermal head, a heating resistor 2 is arranged in parallel with one end of an upper surface of an insulating substrate 1 and the heating resistor 2 is provided with the heating resistor 2. On the other hand, the individual electrode patterns 4 and the independent divided common electrode patterns 3 are alternately arranged in parallel in a direction orthogonal to each other, and the divided common electrode patterns 3 are parallel to the individual electrode patterns 4 in the direction of the other end of the insulating substrate 1 ( The plurality of independent divided common electrode patterns 3 are made common to each other by pulling out toward the drive IC).

The thermal head applies a pulse voltage between the electrode patterns (individual electrode and common electrode) 3 and 4 to selectively cause the heating resistor 2 to generate heat. Information is printed on a recording paper that is pressed and fed in a superposed state with a (thermal ribbon).

[0005]

In the above-described conventional thermal head (shown in FIG. 3) (a head in which the common electrode pattern is located between one end of the insulating substrate and the heating resistor), insulation from the heating resistor is provided. A common electrode pattern having a constant width is located between the substrate and the edge. Both ends of this heating resistor are bent at a right angle, and the bent portion is set to have a U-shape in a plan view in parallel with the individual electrode pattern. The power is supplied from the bent end bent at a right angle, but the length of the common electrode pattern is long,
Since the electric resistance value of the central common electrode pattern is larger than that of the common electrode patterns at both ends, the current supplied to each heating resistor varies. If current capacity is secured in the common electrode pattern to prevent this, the planar size of the "U" -shaped portion of the common electrode pattern becomes large, and there is a problem that the head cannot be downsized. .

Further, in the thermal head (shown in FIG. 2) of the above-mentioned prior application (a head in which the lower end portion of the divided common electrode pattern is made common), the common electrode pattern is formed between one end portion of the insulating substrate and the heating resistor. not exist. Therefore, the heating resistor can be arranged close to one end edge of the insulating substrate, and the demand for miniaturization of the head can be met. However, since the divided common electrode pattern and the individual electrode pattern are drawn out in parallel to each other in the direction of the other end of the insulating substrate (drive IC direction), the number of dots of several thousand hundreds may be temporarily generated like a line type thermal head. In some cases (when the dot density is high), and in the case of a small head, the electrode pattern becomes fine, extremely high precision of etching processing is required, and there is a disadvantage that pattern formation is difficult. . In addition, the common pattern needs to pass between the WB (wibon) pads of the drive IC, which causes a problem that WB accuracy is difficult.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a thermal head capable of ensuring a current capacity of a common electrode pattern while reducing the external dimensions of the thermal head. To aim.

[0008]

In order to achieve this object, the thermal head of the present invention has the following structure. Providing a row of heating resistors on the upper surface of the insulating substrate,
A common electrode pattern consisting of a pattern portion arranged along the heating resistor and a plurality of electrode patterns branched from this pattern portion in a comb shape and formed across the heating resistor, and the common electrode pattern alternates with the electrode pattern. And an individual electrode pattern that is drawn out to the side where the pattern portion is not formed across the heating resistor and sandwiching the heating resistor, and further along the heating resistor on the lead-out side of the individual electrode pattern. Multiple drive ICs arranged in rows
In a thermal head having a plurality of electrode patterns, each of the plurality of electrode patterns is connected to a lead-out pattern formed wider than the width of the electrode pattern, and each of the lead-out patterns is connected to the individual Extends in the same direction as the electrode pattern extraction side,
Further, the extended lead-out pattern is connected to a pattern parallel to the heating resistors provided under the plurality of drive ICs.

The lead-out pattern is characterized in that it has a taper portion that is gradually widened in the extension direction from the connection point so that the maximum width H becomes wider than the electrode pattern width h.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a main part plan view showing a specific embodiment of a thermal head according to the present invention. The thermal head is provided with a heating resistance film on the upper surface of the insulating substrate 1 to form a heating resistor 2, and the heating resistor 2 is formed in the vicinity of the edge of the insulating substrate 1 in parallel with the edge thereof. A common electrode pattern 3 is formed between the heating resistor 2 and the one end edge of the insulating substrate 1. The common electrode pattern 3 crosses the pattern portion 30 parallel to the heating resistor 2 and the heating resistor 2. The electrode pattern 33 has a comb-tooth shape and is integrally formed. On the other hand, an individual electrode pattern 4 is formed across the heating resistor 2 on the upper surface of the insulating substrate 1.
The individual electrode patterns 4 and the comb-teeth-shaped electrode patterns 33 of the common electrode pattern 3 are alternately arranged in sequence on the heating resistor 2 so as to face each other.

Then, some of the electrode patterns 33 extending from the narrow pattern portion 30 located between the one end edge of the insulating substrate 1 and the heating resistor 2 and the heating resistor 2 are provided in parallel. Under a plurality of drive ICs 5 arranged in a row, a lead-out pattern 31 is integrally formed so as to be connected to a pattern 32 provided in parallel with the heating resistor 2 in the direction of the other end of the insulating substrate 1. ing. The lead pattern 31 is connected to the electrode pattern 33 at a connection point A.
To the other end of the insulating substrate 1, the taper portion 31a having a width gradually widening, and the wide portion 31b having the largest width H connected to the parallel pattern 32 connected to the taper portion 31a.
And the width dimension H of the wide portion 31b is the electrode pattern 3
The width is larger than the width h of 3.

In an actual line type thermal head, there are several thousand heating dots and a plurality of drive ICs 5 are arranged. The single drive IC 5 is in charge of 64 dots, for example. Therefore, 64 electrode patterns 4 are connected to one IC 5. However, in the drawing (FIG. 1), for the sake of simplification, eight dots are shown for each of the single drive ICs 5, and eight individual electrode patterns 4 are arranged to select these eight dots. Along with the adjacent drive I
Only the comb-teeth-shaped electrode pattern 33 of the common electrode pattern 3 located between C5 and C5 is drawn out in the direction of the other end of the insulating substrate 1 (drive IC direction), and the lower end of the drawn-out pattern 31 is parallel to this. The drive IC 5 is mounted on the pattern 32. Further, the individual electrode patterns (8 individual electrode patterns) 4 are wire-bonded to the drive IC 5 at the pad portions 41 at the ends.

In the thermal head having such a structure, the common electrode pattern 3 arranged between the heating resistor 2 and the edge of the insulating substrate 1 is provided between the drive ICs 5 and 5 adjacent to each other, and The extension pattern portion 31 was formed by extending in the end direction. As a result, by pulling out the common electrode pattern 3 for each drive IC 5,
A current for one piece will flow to the common electrode pattern 3. Actually, only the current of one drive IC 5 is used for the electrode used as the common, so that the common electrode pattern 3 having a large width is not necessary. Therefore, the common electrode pattern 3 arranged between the heating resistor 2 and the edge of the insulating substrate 1 can be set to be extremely narrow, and the insulating resistor 1 can be miniaturized accordingly.

Further, since the common electrode pattern 3 is drawn from between the drive ICs 5 and 5 adjacent to each other by the drawing pattern 31 toward the other end of the insulating substrate 1, the number of drawing the common electrode pattern 3 is drastically reduced. In other words, only one extraction pattern 31 of the common electrode pattern 3 is extracted for each single drive IC 5, and the pattern formation density of each electrode pattern 3, 4 is reduced. Therefore, drive IC5
There is a margin in the arrangement interval between the individual electrode patterns 4 and the common electrode pattern 3 arranged therebetween, and the etching process becomes extremely easy.

[0015]

Since the parallel pattern is formed in the lower part of the drive IC by adopting the structure of claim 1, the pattern is widened to secure the total current capacity of the plurality of lead-out patterns to be connected. Even if it is necessary to do so, the current capacity can be secured without increasing the width dimension of the thermal head itself. That is,
The thermal head can be miniaturized by effectively utilizing the mounting space of the drive IC.

Further, by making the width of the lead-out pattern wider than that of the electrode pattern, the lead-out pattern can be applied even if an electric current flows through the electrode pattern connected to the lead-out pattern several times as compared with an electrode not connected to another lead-out pattern. The substantially central portion of the electrode pattern connected to, that is, the portion that overlaps with the heating resistor or the vicinity of the heating resistor only generates heat, and there is an advantage that the drawing pattern does not generate heat and affects print quality.

Further, by adopting the structure of claim 2, since the lead-out pattern has a taper portion which is gradually widened from the connection portion with the electrode pattern, the etching process is facilitated. That is, when the width dimension is suddenly changed from the narrow width portion to the wide portion, there is a possibility that the etching liquid permeates into the corner portion and the pattern is broken. However, with the above configuration, such a possibility is small.

Further, since the lead-out pattern has the taper portion which is gradually widened from the connection portion with the electrode pattern, it is possible to avoid the possibility that the current is concentrated at the connection portion and the heating resistor is destroyed.

[Brief description of drawings]

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

FIG. 2 is a plan view of an essential part showing a thermal head according to a prior application.

FIG. 3 is a plan view of a main part showing a conventional thermal head.

[Explanation of symbols]

 1 ... Insulating substrate 2 ... Heating resistor 3 ... Common electrode pattern 4 ... Individual electrode pattern 5 ... Drive IC

Claims (2)

[Claims] 1. A column-shaped heating resistor is provided on an upper surface of an insulating substrate, and a pattern portion arranged along the heating resistor and a comb-shaped branch from the pattern portion are formed across the heating resistor. A common electrode pattern composed of a plurality of electrode patterns, and an individual electrode pattern that is drawn out to the side where the pattern portion is not formed across the heating resistor alternately with the electrode pattern and sandwiching the heating resistor. And a plurality of drive ICs arranged in a row along the heating resistor on the lead-out side of the individual electrode pattern, wherein some of the plurality of electrode patterns are provided. Connect the lead-out patterns formed wider than the width of the electrode pattern, and each of the lead-out patterns is connected to the individual electrode pattern. The extended drawing pattern is extended in the same direction as the drawing side of the battery, and the extended drawing pattern is connected to a parallel pattern to the heating resistors provided under the plurality of drive ICs. Thermal head. 2. The lead-out pattern has a taper portion that is gradually widened in the extension direction from the connection point so that the maximum width H is wider than the electrode pattern width h. Thermal head.