JP3167262B2 - Line type thermal print head - Google Patents

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 machine.

[0002]

2. Description of the Related Art In general, a line type thermal print head of this type is formed on a surface of a rectangular head substrate.
While the heating resistor is formed so as to extend in a straight line in the longitudinal direction, a common wiring pattern that conducts for each print dot in the heating resistor is provided on one longitudinal edge of the surface of the head substrate. It is formed so as to extend along the heating resistor, and is further connected to a portion of the surface of the head substrate opposite to a common wiring pattern across the heating resistor for each print dot of the heating resistor. A large number of individual wiring patterns are formed, and a plurality of drive circuit elements for connecting the individual wiring patterns and a ground wiring pattern formed on the surface of the head substrate so as to extend in the longitudinal direction are mounted. In the configuration, by switching of each of the drive circuit elements,
By electrically connecting the ground wiring pattern to any of the individual wiring patterns,
In this configuration, an arbitrary print dot in the heating resistor is energized to generate heat.

The ground wiring pattern and the common wiring pattern in the line type thermal print head have a configuration extending long along a linear heating resistor and are configured to supply power to one 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.

Accordingly, Japanese Patent Application Laid-Open No. 2-28 as a prior art is disclosed.
No. 6261 (Japanese Patent Publication No. 4-17797) discloses that the ground wiring pattern is divided into a right ground wiring pattern and a left ground wiring pattern at a substantially central portion of the head substrate, while the longitudinal one side edge is divided. A pair of ground connection terminals electrically connected to each of the two ground wiring patterns, and a pair of common terminals electrically connected to both ends of the common wiring pattern, at a substantially central portion in the longitudinal direction of the other long side edge on the opposite side to the above. It has been proposed that the connection terminals are formed such that both common connection terminals are located inside both ground connection terminals.

In this prior art, the voltage drop in the common wiring pattern is increased toward the center, 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 longitudinal direction, thereby reducing the printing density difference caused by the voltage drop.

[0006]

However, if the ground wiring pattern is divided into a ground wiring pattern on the right side and a ground wiring pattern on the left side as in this prior art, the two ground wiring patterns are separated. If the number of dots to be printed on the right ground wiring pattern is different from the number of dots to be printed on the left ground wiring pattern when printing using Because a voltage difference is created 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 using one ground wiring pattern and printing using the other ground wiring pattern There is a problem that a density difference occurs between printing and printing.

In the prior art, both common connection terminals are located inside both 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 it is possible to extend both ground connection terminals to the other long side edge of the head substrate. When connecting various external wirings or connectors to these ground connection terminals, there is no connection between the ground connection terminals and the other long side edge of the head substrate. It is necessary to jump over the common connection wiring pattern. That it is difficult to connect the socket and the like was also a problem.

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

[0009]

SUMMARY OF THE INVENTION In order to address this technical problem, the present invention provides a method for forming a heating resistor on a surface of a head substrate so as to extend linearly, A common wiring pattern that is conductive for each print dot in the heating resistor is formed on a portion from one side edge parallel to the heating resistor so as to extend along the heating resistor, and further includes a surface of the head substrate. A plurality of individual wiring patterns that are electrically connected to each print dot in the heating resistor are formed in a portion of the heating resistor opposite to the common wiring pattern, and each of the individual wiring patterns and the head substrate Thermal print head having a plurality of drive circuit elements connected to a ground wiring pattern formed on the surface of the device so as to extend along the heating resistor. 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 is electrically connected to a substantially central portion in the longitudinal direction of the ground wiring pattern and a pair of common connection terminals that are electrically connected to both ends of the common wiring pattern are formed. ".

[0010]

As described above, the ground wiring pattern is not divided into the right part and the left part with the substantially central part as a boundary, but is formed at the substantially central part in the longitudinal direction at the other side edge of the head substrate. By conducting the ground connection terminal formed substantially at the center, power for printing is simultaneously supplied to the right and left portions of the ground wiring pattern via the ground connection terminal. And the power supplied to the right portion of the ground wiring pattern and the power supplied to the left portion of the ground wiring pattern come and go with each other. When the number of dots printed on the right part of the ground wiring pattern and the number of dots printed on the left part 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, as in the prior art, the voltage difference between the common wiring pattern and the ground wiring pattern can be reduced. Since the voltage difference between the left part and the left part can be reduced, these can be combined to make the print density difference between the right part and the left part of the ground wiring pattern substantially equal, and Quality can be greatly improved.

Further, as described in claim 2, the ground connection terminal and both common connection terminals are formed such that 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 side edge of the head substrate, it is necessary to connect various wirings or connection connectors to the outside to these. However, it is possible to simply, easily, and surely without causing an electric 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.
Shows a head substrate formed in a rectangular shape from a heat-resistant insulating material such as ceramic. On the upper surface of the head substrate 1, a heating resistor 2 forming a large number of print dots is provided on one side edge 1a of the head substrate 1. The head substrate 1 is formed so as to extend in a line shape substantially in parallel with the heating resistor 2 at a portion from one side edge 1a parallel to the heating resistor 2.
A common wiring pattern 3 that is conductive for each print dot on the heating resistor 2 is formed so as to extend along the heating resistor 2.

On the upper surface of the head substrate 1, on the opposite side of the heating resistor 2 from the common wiring pattern 3, there are provided a large number of individual conductive members for each printing dot of the heating resistor 2. The wiring patterns 4 are formed, and a plurality of drive circuit elements 5 that are electrically connected to the individual wiring patterns 4 are mounted in a line along the heating resistor 2.

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

As described above, 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. 8, the printing power can be simultaneously supplied to the right and left portions of the ground wiring pattern 7 via the ground connection terminal 8, and the ground wiring pattern 7 can be supplied. Since the power supplied to the right portion and the power supplied to the left portion of the ground wiring pattern come and go with each other, when printing is performed over the entire length of the ground wiring pattern 7, When the number of dots to be printed in the right portion and the number of dots to be printed in the left portion are different, the ground wiring pattern 7 is replaced. And the right portion is able reliably prevent the voltage difference between the left part is generated.

The common connection terminals 12 and 13 with respect to both ends of the common wiring pattern 3 are located outside the ground connection terminal 8 with respect to a substantially central portion of the ground wiring pattern 7. Both the ground connection terminal 8 and both common connection terminals 12 and 13 are not disturbed by the common connection wiring patterns 10 and 11 from both ends of the common wiring pattern as in the prior art, as shown in the figure. In addition, it can be extended to the other side edge 1b of the head substrate 1.

Therefore, with respect to the head substrate 1, for example,
When the connection connector 14 having a plurality of terminal pins 14b fixed thereto is mounted in the box 14a, the forked holding portion 14b 'of each terminal pin 14b of the connector 14 is connected to the other side edge of the head substrate 1. 1b, the connector 14 is
Are connected to the ground connection terminal 8, the various signal connection terminals 9, and both common connection terminals 1.
It can be mounted in a state in which it is electrically connected to each of 2 and 13.

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

Further, various wirings to the outside may be directly connected to the ground connection terminal 9, the various signal connection terminals 10, and the common connection terminals 13 and 14, respectively. Good, in any case,
The ground connection terminal 9, various signal connection terminals 10, and both common connection terminals 13, 14 extend to the other side edge 1 b of the head substrate 1. The connection of the connection connector or the like is more likely to cause an electrical short-circuit than when the common connection wiring pattern exists between the ground connection terminal and the other side edge of the head substrate as in the prior art. This can be done simply, easily, and reliably without any occurrence.

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

[Brief description of the 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 of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head board 2 Heating resistor 3 Common wiring pattern 4 Individual wiring pattern 5 Drive 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/345 B41J 2/335

Claims (2)

(57) [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 formed on a portion of the surface of the head substrate from one side edge parallel to the heating resistor. Forming a common wiring pattern that is conductive for each print dot on the body so as to extend along the heating resistor; and furthermore, a portion of the surface of the head substrate opposite to the common wiring pattern across the heating resistor. A plurality of individual wiring patterns that are conducted for each print dot on the heating resistor, and a ground wiring formed on the surface of the individual wiring pattern and the head substrate so as to extend along the heating resistor. In a thermal print head including a plurality of drive circuit elements connected to a pattern, the thermal print head further includes: At 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 conduct to both ends of the common wiring pattern are formed. Characteristic line type thermal print head. 2. The method according to claim 1, wherein the ground connection terminal and the 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.