JPH0528644U - Thermal head wiring pattern - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the bonding wires from overlapping with the wiring pattern of the thermal head in which the power supply connection pattern is formed in a position parallel to the ground side lead conductor. [Structure] A positional relationship between a ground side lead conductor and a conductor pad for connecting the ground side lead conductor to a connection terminal of a control circuit IC is adjusted.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wiring pattern of a thermal head used in a thermal recording device.

[0002]

[Prior Art]

 FIG. 3 is a connection diagram for explaining the operation of the thermal head. In the figure, 1 is a heating resistor, 2 is a control circuit IC, 3 is a power supply, 4 is a common electrode, 5 is a ground electrode, and 6 is a power supply side wiring pattern. Reference numeral 7 denotes a ground side wiring pattern, and 70 denotes a ground side lead conductor formed integrally with the ground side wiring pattern 7. The control circuit IC2 connects the ground side lead conductor 70 (single or plural) selected by external control to the ground electrode 5. A current flows between the grounded side wiring pattern 7 and the power source side wiring patterns 6 on both sides of the grounded side wiring pattern 7, and the portion of the heating resistor 1 in the section between them generates heat, and thermal recording is performed at this portion. . Therefore, if the voltage drop in the common electrode 4 and the ground electrode 5 is large, the recording quality will deteriorate.

FIG. 4 is a schematic plan view showing an example of a wiring pattern corresponding to FIG. 3. The same reference numerals as those in FIG. 3 denote the same or corresponding parts, 8 is a ceramic substrate, 21 is a connection terminal of the control circuit IC 2, 71 Is a conductor pad, and 72 shown by a dotted line is a bonding wire. The heating resistor 1, the control circuit IC 2, the common electrode 4, the power source side wiring pattern 6, the ground side wiring pattern 7, the ground side lead conductor 70, and the conductor pad 71 are formed on the substrate 8 and correspond to the conductor pad 71. The connection terminal 21 is connected with a bonding wire. The heating resistor 1 is formed in a linear shape. If the direction of this straight line is the Y direction and the direction perpendicular to the Y direction is the X direction, the power source side wiring pattern 6, the ground side wiring pattern 7, and the ground side lead conductor 70 are , Are formed in parallel with the X direction on the substrate 8.

In order to reduce the voltage drop in the common electrode 4, the common electrode 4 must be formed in a pattern having a large width in the X direction, and the position of the heating resistor 1 should be as close as possible to the end of the substrate 8 in the X direction. In the edge type thermal head that needs to be placed, the wiring pattern as shown in FIG. 4 is not preferable.

As a wiring pattern suitable for an edge type thermal head, Japanese Patent Application No. 2-221118, “Wiring pattern on the power supply side of the thermal head array,” and Japanese Patent Application No. 2-403603, which the applicant of the present application previously applied, Power supply side wiring pattern of thermal head array, Japanese Patent Application No. 3-48676 "Power supply side wiring pattern of thermal head array", Japanese Patent Application No. 3-32690 "The structure of thermal head array" (hereinafter collectively referred to as There is an application). FIG. 5 is a schematic plan view showing a wiring pattern of an edge type thermal head designed according to the prior application. The same reference numerals as those in FIG. 4 indicate the same or corresponding portions, and 41 is a power supply connection pattern. Although a plurality of power supply connection patterns 41 are provided, FIG. 5 shows only one power supply connection pattern 41 and a wiring pattern near the power supply connection pattern 41.

In the design shown in FIG. 5, since the heating resistor 1 is located as close as possible to the end in the X direction on the substrate 8, the width of the common electrode 4 in the X direction is reduced, and if the voltage drop therein is not a problem. Therefore, the positive terminal of the power source is connected to a plurality of locations of the common electrode 4 by the plurality of power source connection patterns 41. The structure for connecting the positive terminal of the power supply to each power supply connection pattern 41 has been described in the previous application, and the description thereof is omitted because it has no direct relation to the present invention.

Each power supply connection pattern 41 has a width in the Y direction to reduce the electric resistance and is formed parallel to the X direction, and the width in the Y direction is tapered in the vicinity of the heating resistor 1 to correspond to the power supply side. Connect to the wiring pattern. Comparing FIG. 4 and FIG. 5, the dimension in the Y 2 direction assigned to the array of the ground side lead conductors 70 is reduced in FIG. 5 by the width of the power supply connection pattern 41 as compared with FIG. 4. In the embodiment shown in FIG. 5, the ground side lead conductors 70 parallel to the X direction are formed at equal intervals in the reduced width in the Y direction. A corresponding conductor pad 71 is formed so that each lead conductor 70 is connected to the center. Each ground side lead conductor 70 is connected to the corresponding ground side wiring pattern 7 near the heating resistor 1.

[0008]

[Problems to be solved by the device]

 The problem to be solved is that in the conventional thermal head wiring pattern as described above, there is a risk that the bonding wires will overlap. That is, in the wiring pattern shown in FIG. 5, the ground-side lead conductor 70 is formed avoiding the power supply connection pattern 41 while the relationship between the power supply side wiring pattern 6 and the control circuit IC2 is kept the same as in the case of FIG. Since the conductor pads 71 are formed at the positions related to the ground-side lead conductors 70, the bonding wires 72 from the conductor pads 71 to the corresponding connection terminals 21 may overlap.

The present invention has been made to solve the above problems, and an object thereof is to provide a wiring pattern for a thermal head that has a simple structure and can avoid the risk of overlapping bonding wires.

[0010]

[Means for Solving the Problems]

 In the wiring pattern of the thermal head according to the present invention, the position of the corresponding conductor pad is changed with respect to the ground side wiring pattern, and the positional relationship with the conductor pad is adjusted.

[0011]

【Example】

 FIG. 2 is a plan view showing the positional relationship between the ground-side lead conductor 70 and the conductor pad 71 according to an embodiment of the present invention, which is a fixed contact as shown in FIGS. 2 (a), 2 (b) and 2 (c). In one numerical example, the conductor pad 71 can be moved with respect to the side lead conductor 70 within a range of ± 75 μm, and the center of the corresponding connection terminal 21 is moved from the center of the conductor pad 71 within this range. It is possible to prevent the bonding wires from overlapping each other by appropriately separating the line segment connecting the lines from the line connecting the centers of the adjacent connection pads 21 from the center of the adjacent conductor pad 71.

FIG. 1 is a schematic plan view showing an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 5 indicate the same or corresponding portions, and the difference from FIG. 5 is the corresponding conductor pad for the ground side lead conductor 70. 71 is the position movement. In this position movement, for example, the optimum position can be determined by an enlarged view at the time of designing. In the wiring pattern of FIG. 1, the risk of the bonding wires overlapping can be sufficiently reduced as compared with the wiring pattern of FIG.

[0013]

[Effect of the device]

 As described above, the wiring pattern of the thermal head of the present invention has the effect of avoiding the risk of overlapping bonding wires.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an embodiment of the present invention.

FIG. 2 is a schematic plan view showing a positional relationship between a ground side lead conductor and a conductor pad according to an embodiment of the present invention.

FIG. 3 is a connection diagram for explaining the operation of the thermal head.

FIG. 4 is a schematic plan view showing an example of a conventional device.

FIG. 5 is a schematic plan view showing another example of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating resistor 2 Control circuit IC 4 Common electrode 6 Power supply side wiring pattern 7 Grounding side wiring pattern 21 Connection terminal 41 Power supply connecting pattern 70 Grounding side lead conductor 71 Conductor pad 72 Bonding wire

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koichi Takahashi 503-10 Shinanomachi, Totsuka-ku, Yokohama, Kanagawa Prefecture Graphtec Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A linear heating resistor is formed on a substrate,
A plurality of conductors contacting and crossing the heating resistor in a direction (X direction) perpendicular to the straight line (Y direction) of the heating resistor are formed at equal intervals in the Y direction. Every other conductor is used as the power supply side wiring pattern and the ground side wiring pattern, all the power source side wiring patterns are connected in parallel and connected to the positive side terminal of the power supply, and all the ground side wiring patterns are connected via their respective lead conductors. In a wiring pattern of a thermal head configured to be connected to a control circuit IC and to connect the lead conductor (s) selected by the operation of the control circuit IC to the negative terminal of the power source, regarding the heating resistor on the substrate. A common electrode formed on the opposite side to the control circuit IC and connected in parallel to the power supply side wiring pattern, and on the substrate on the same side as the control circuit IC with respect to the heating resistor, each has a width in the Y direction. A plurality of power supply connection patterns formed in parallel with the X direction and having a width in the Y direction tapered near the heating resistors and connected to the power supply side wiring patterns facing each other. Means for connecting all power supply connection patterns to the positive terminal of the power supply, adjacent to each other 2
Equipped with each ground side lead conductor pattern which is formed in parallel in the X direction by equally dividing the Y direction interval between the individual power source connection patterns and connected to the corresponding ground side wiring pattern in the vicinity of the heating resistor, In order to connect each ground-side lead conductor pattern to the corresponding connection terminal of the control circuit IC by wire bonding, each conductor pad formed by connecting to the ground-side lead conductor pattern on the substrate is arranged from the center of the conductor pad. A wiring pattern for a thermal head, characterized in that it is formed such that a line segment reaching the center of a corresponding connection terminal is sufficiently separated from a line segment reaching the center of an adjacent connection terminal from the center of an adjacent conductor pad.