JPH0939284A - Line type thermal printing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the printing density difference over the entire length in a line type thermal printing head that a common wiring pattern and a ground wiring pattern are so formed via a line-like heating resistor as to extend in parallel on the surface of a head board. SOLUTION: A ground connecting terminal 8 for conducting a ground wiring pattern 7 substantially in the center of a lengthwise direction is provided substantially at the central direction of the lengthwise direction of a head board 1, and a pair of common connecting terminals 12, 13 to both ends of a common wiring pattern 3 are provided at both outsides of the terminal 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line type thermal print head used for printing on a printer such as a facsimile.

[0002]

2. Description of the Related Art Generally, a line type thermal print head of this type has a rectangular surface on a head substrate.
The heating resistor is formed so as to extend in a straight line shape in the longitudinal direction, and a common wiring pattern that conducts for each print dot in the heating resistor is formed on one longitudinal edge portion of the surface of the head substrate. The heating resistor is formed so as to extend along the heating resistor, and is connected to a portion of the surface of the head substrate opposite to the common wiring pattern across the heating resistor for each print dot of the heating resistor. In addition to forming a large number of individual wiring patterns, a plurality of drive circuit elements for connecting each individual wiring pattern and a ground wiring pattern formed so as to extend in the longitudinal direction on the surface of the head substrate are mounted. With the configuration, by switching each of the drive circuit elements,
By electrically connecting the ground wiring pattern and any individual wiring pattern among the individual wiring patterns,
It is designed to generate heat by energizing arbitrary print dots in the heating resistor.

By the way, the ground wiring pattern and the common wiring pattern in this line-type thermal print head have a shape that extends long along the line-shaped heat-generating resistor, and that power is supplied to one end or both ends thereof. , There is a voltage drop along its length,
Due to this voltage drop, a density difference occurs in printing by each print dot on the heating resistor.

Therefore, as a prior art, Japanese Patent Laid-Open No. 2-28
6261 (Japanese Patent Publication No. 4-17797) divides the ground wiring pattern into a ground wiring pattern on the right side and a ground wiring pattern on the left side at a substantially central portion of the head substrate, while the longitudinal one side edge is formed. A pair of ground connection terminals that are electrically connected to each of the ground wiring patterns and a pair of commons that are electrically connected to both ends of the common wiring pattern, respectively, at approximately the center in the longitudinal direction on the other side edge on the opposite side to It is proposed that the connection terminals and the common connection terminals are formed inside the ground connection terminals.

In the prior art, the voltage drop in the common wiring pattern is increased toward the central portion, and the voltage drop in both ground wiring patterns is increased toward both ends. The voltage between the wiring pattern and the wiring pattern is kept substantially constant along the lengthwise direction, and the difference in print density due to the voltage drop is reduced.

[0006]

However, when the ground wiring pattern is divided into the right-side ground wiring pattern and the left-side ground wiring pattern as in this prior art, both ground wiring patterns are separated. When printing using, when the number of dots printed with the ground wiring pattern on the right side and the number of dots printed with the ground wiring pattern on the left side are different, perform printing. Since there is a voltage difference between the ground wiring pattern with a large number of dots and the ground wiring pattern with a small number of dots being printed, printing with one ground wiring pattern and printing with the other ground wiring pattern There is a problem in that a density difference occurs between printing and printing.

In the prior art, the common connection terminals are located inside the ground connection terminals, and between the ground connection terminal and the other longitudinal edge of the head substrate. There is a common connection wiring pattern for conducting both ends of the common wiring pattern to both common connection terminals, and these ground connection terminals can be extended to the other longitudinal edge of the head substrate. Therefore, when connecting various wiring to the outside or a connector for connection to these ground connection terminals, there is a gap between the ground connection terminals and the other longitudinal edge of the head substrate. Since it is necessary to jump over the common connection wiring pattern that is present, various wiring or connection to the outside for these ground connection terminals That it is difficult to connect the socket and the like was also a problem.

It is a technical object of the present invention to provide a line type thermal print head capable of solving these problems.

[0009]

In order to address this technical problem, the present invention discloses that "a heating resistor is formed on a surface of a head substrate so as to extend in a line shape, and A common wiring pattern for conducting each print dot in the heating resistor is formed so as to extend along the heating resistor in a portion extending from one side edge parallel to the heating resistor, and the surface of the head substrate is further formed. A plurality of individual wiring patterns that are electrically connected to each print dot of the heating resistor are formed in a portion opposite to the common wiring pattern with the heating resistor interposed therebetween, and each individual wiring pattern and the head substrate are formed. Thermal print head having a plurality of drive circuit elements connected to the ground wiring pattern formed so as to extend along the heating resistor on the surface of the Oite, the substantially central portion in the other side edge opposite to the one side edge of the head substrate surface,
A ground connection terminal that conducts to a substantially central portion in the longitudinal direction of the ground wiring pattern and a pair of common connection terminals that conducts to both ends of the common wiring pattern are formed. ".

[0010]

As described above, the ground wiring pattern is not divided into the right portion and the left portion with the substantially central portion as a boundary, and the ground wiring pattern is provided at the substantially central portion in the longitudinal direction at the other side edge of the head substrate. By electrically connecting the ground connection terminal formed in the approximate center, printing power can be simultaneously supplied to the right side part and the left side part of the ground wiring pattern via this ground connection terminal. At the same time, the power supplied to the right part of the ground wiring pattern and the power supplied to the left part of the ground wiring pattern go back and forth, so when printing over the entire length of the ground wiring pattern, When the number of dots printed on the right side of the ground wiring pattern and the number of dots printed on the left side are different And the right portion of the ground wiring pattern, can be reliably prevented that the voltage difference generated between the left part.

Therefore, according to the present invention, the voltage difference between the common wiring pattern and the ground wiring pattern can be reduced, and the right side portion of the ground wiring pattern is Since the voltage difference between the left side part and the left side part can be made small, they can work together to make the print density difference between the right side part and the left side part of the ground wiring pattern substantially equal to each other. The quality can be greatly improved.

Further, as described in "Claim 2," the ground connection terminal and the both-common connection terminal are formed such that the both-common connection terminals are located outside the ground connection terminal. Since both the ground connection terminal and both common connection terminals can be extended to the other longitudinal edge of the head substrate, various external wiring or connection connectors or the like should be connected to them. However, it can be done easily, easily and surely without causing an electrical short circuit.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.
The drawing of FIG. 3 will be described. In FIG.
Indicates a rectangular head substrate made of a heat-resistant insulating material such as ceramic. On the upper surface of the head substrate 1, heating resistors 2 forming a large number of print dots are formed on one side edge 1a of the head substrate 1. Is formed so as to extend in a line shape substantially parallel to, and on a portion of the upper surface of the head substrate 1 from one side edge 1a parallel to the heating resistor 2,
A common wiring pattern 3 that is electrically connected to each print dot in the heating resistor 2 is formed so as to extend along the heating resistor 2.

Further, in the portion of the upper surface of the head substrate 1 opposite to the common wiring pattern 3 with the heating resistor 2 interposed therebetween, a large number of individual conductive dots for each printing dot of the heating resistor 2 are provided. The wiring pattern 4 is formed, and a plurality of drive circuit elements 5 that are electrically connected to the individual wiring patterns 4 are mounted so as to be arranged in a line along the heating resistor 2.

Furthermore, in the portion of the upper surface of the head substrate 1 between each of the drive circuit elements 5 and the other side edge 1b of the head substrate 1, a metal is wire-bonded to each of the drive circuit elements 5. A ground wiring pattern 7 that is electrically connected through the line 6 is formed so as to extend substantially in parallel along the row of each drive circuit element 5. Then, in a portion of the upper surface of the head substrate 1 from the other side edge 1b, and
A wide ground connection terminal 8 is formed at a substantially central portion in the longitudinal direction so as to be electrically connected to the substantially central portion in the longitudinal direction of the ground wiring pattern 7, and is formed on both outer sides of the ground connection terminal 8. , A plurality of signal connection terminals 9 for supplying various signals to each of the drive circuit elements 5 are formed, and further, on both outer sides of each of the signal connection terminals 9, the common wiring pattern 3 is formed. A wide pair of common connection terminals 12 and 13 are formed on both ends of the common connection wiring patterns 10 and 11, respectively.

In this way, the ground wiring pattern 7 is
A ground connection terminal formed at a substantially central portion of the other side edge 1b of the head substrate 1 at a substantially central portion in the longitudinal direction without being divided into a right portion and a left portion with the substantially central portion as a boundary. By making 8 conductive, it is possible to simultaneously supply printing power to the right side portion and the left side portion of the ground wiring pattern 7 via the ground connection terminal 8 and at the same time. The electric power supplied to the right part of the ground wiring pattern 7 and the electric power supplied to the left part of the ground wiring pattern 7 go back and forth from each other. When the number of dots printed on the right side and the number of dots printed on the left are different, the ground wiring pattern 7 And the right portion is able reliably prevent the voltage difference between the left part is generated.

The common connection terminals 12 and 13 for both ends of the common wiring pattern 3 are located outside the ground connection terminal 8 with respect to the substantially central portion of the ground wiring pattern 7. Both the ground connection terminal 8 and both common connection terminals 12 and 13 are as shown in the figure without being disturbed by the common connection wiring patterns 10 and 11 from both ends of the common wiring pattern as in the prior art. In addition, the head substrate 1 can be extended to the other side edge 1b.

Therefore, for the head substrate 1, for example,
When mounting the connector 14 for connection, which is formed by fixing a plurality of terminal pins 14b in the box 14a, the bifurcated holding portion 14b 'of each terminal pin 14b of the connector 14 is attached to the other side edge of the head substrate 1. By fitting the connector 14 onto the connector 1b,
Each terminal pin 14b in the above is connected to the ground connection terminal 8, various signal connection terminals 9 and both common connection terminals 1
2 and 13 can be attached while being electrically connected.

In this embodiment, the connector 14 is
Of the terminal pins 14b, seven terminal pins are ground connection terminals 8, three terminal pins are one common connection terminal 12, and four terminal pins are the other common connection terminal 13. The forked holding portion 14b 'of each terminal pin 14b is fitted to the other side edge 1b of the head substrate 1 and then fixed by soldering or conductive paste. Has been done.

Further, various wirings to the outside may be directly connected to the ground connection terminal 9, various signal connection terminals 10 and both common connection terminals 13 and 14, respectively. Good, and in any case,
Since the ground connection terminal 9, various signal connection terminals 10 and both common connection terminals 13 and 14 extend to the other side edge 1b of the head substrate 1, various external wiring or Connecting a connecting connector or the like causes an electrical short circuit as compared with the case where the common connecting wiring pattern exists between the ground connecting terminal and the other side edge of the head substrate as in the above-mentioned prior art. It can be performed easily, easily and surely without any occurrence.

Furthermore, on the upper surface of the head substrate 1,
As shown by the chain double-dashed line in FIG. 3, a glass coat 15 that covers the heating resistor 2, the common wiring pattern 3, and each ground wiring pattern 4, and a resin coat 1 that covers each drive circuit element 5.
6 and 6 are applied respectively.

[Brief description of drawings]

FIG. 1 is an overall perspective view according to an embodiment of the present invention.

FIG. 2 is an enlarged plan view of a main part of FIG.

FIG. 3 is an enlarged sectional view taken along line III-III in FIG.

[Explanation of symbols]

 1 Head Board 2 Heating Resistor 3 Common Wiring Pattern 4 Individual Wiring Pattern 5 Driving Circuit Element 6 Metal Wire 7 Ground Wiring Pattern 8 Ground Connection Terminal 9 Signal Connection Terminal 10, 11 Common Connection Wiring Pattern 12, 13 Common Connection Terminal 14 Connector 14a Box 14b Terminal pin

Claims (2)

[Claims] 1. A heating resistor is formed on a surface of a head substrate so as to extend in a line shape, and the heating resistor is provided on a portion of a surface of the head substrate which is parallel to the heating resistor and is closer to one side edge. A common wiring pattern that conducts for each print dot in the body is formed so as to extend along the heating resistor, and further, a portion of the surface of the head substrate opposite to the common wiring pattern with the heating resistor interposed therebetween. In addition to forming a large number of individual wiring patterns that conduct each print dot in the heating resistor, the individual wiring patterns and the ground wiring formed on the surface of the head substrate so as to extend along the heating resistor. A thermal print head comprising a plurality of drive circuit elements for connecting to a pattern, comprising: In a substantially central portion of the side edge, a ground connection terminal that conducts to a substantially central portion in the longitudinal direction of the ground wiring pattern and a pair of common connection terminals that conducts to both ends of the common wiring pattern are formed. Characteristic line type thermal print head. 2. The "claim 1" according to claim 1, wherein the ground connection terminal and a pair of common connection terminals are formed such that both common connection terminals are located outside the ground connection terminal. Characteristic line type thermal print head.