JPH07125280A - Structure of line type thermal print head - Google Patents

Abstract

PURPOSE:To reduce a voltage drop by so placing a plurality of semiconductor chips on an upper surface of a common lead for electrically connecting many common side electrodes to unit resistor dots through an insulating layer as to extend the common lead substantially in parallel with a print line between the print line on an upper surface of a head board and a circuit board. CONSTITUTION:A common lead 5 for electrically connecting unit resistor dots 4a through many common side electrodes 9 is so extended between a print line 4 on an upper surface of a head board 2 and a circuit board 3 as to extend substantially in parallel with the line 4. A plurality of semiconductor chips 7 are placed on an upper surface of the lead 5 through an insulating layer 6 in a state in which the chips 7 are aligned in one row state, while the lead 5 is so electrically connected to a common wiring pattern 13 on an upper surface of the board 3 via a common metal lead 14 between input terminals 7b of the chips 7 and control signal metal line 12 for connecting the terminals 7b to control signal wiring pattern 11 of the board 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line of a thermal print head used in a facsimile or a printer, the print width of which is increased to fill the width of a relatively wide sheet such as A-row No. 4 or the like. Type thermal print head structure.

[0002]

2. Description of the Related Art Conventionally, a line type thermal print head of this type, for example, as described in Japanese Patent Application Laid-Open No. 2-103157, and as shown in FIGS. A print line C in which a large number of unit resistor dots are arranged in a line is formed on the upper surface of the head substrate B fixedly attached to the head substrate B so as to extend in parallel to the longitudinal one side face B1 of the head substrate B, and the print line C with respect to the print line C is formed. A wide common lead D is formed so as to extend parallel to the print line C along one longitudinal side surface B1 of the head substrate B, and further, each unit of the print line C is formed on the upper surface of the head substrate B. A plurality of driving semiconductor chips E mounted in a line on the upper surface of the resistor dots and the head substrate B.
A large number of individual leads F for connecting to each other, each unit resistor dot in the print line C, and the common lead D.
Forming a number of common electrodes G for connecting
The individual leads F and the output terminals of the driving semiconductor chips E are electrically connected by wire bonding with a metal wire H or the like.

Further, the control signal metal wire L is provided between each input terminal of each driving semiconductor chip E and each control signal wiring pattern K1 on the upper surface of the circuit board J fixed to the heat dissipation plate A. While electrically connecting by wire bonding or the like by means of wire bonding between the both ends D1 and D2 of the common lead D and the common wiring pattern K2 on the upper surface of the circuit board J, wire bonding by means of a common metal wire M or the like. In this configuration, it is electrically connected.

[0004]

However, the conventional line type thermal print head has the following problems. That is, in this line-type thermal print head, the length of the common lead D becomes considerably long, so that the voltage drop along the longitudinal direction of the common lead D becomes large.

Therefore, conventionally, the width W'in the wide common lead D is further increased or the common lead D is formed into a two-layer or three-layer structure to reduce the voltage drop along the longitudinal direction. Although the width is reduced, the wide common lead D exists between the print line C and the longitudinal one side surface B1 of the head substrate B, so that the longitudinal one side surface B of the head substrate B is present.
The dimension T'between 1 and the print line C must be increased by the amount of the wide common lead D provided between the print line C and the print line C. Since it is largely separated from B1, the printing characteristics of the printing line C are considerably deteriorated, and moreover, both end portions D of the common lead D are
Since 1, 1 and D2 are arranged at portions outside both ends of the print line C, the length dimension of the head substrate B is increased by the both ends D1 and D2 of the common lead D. .

It is a technical object of the present invention to solve these problems and increase the number of driving semiconductor chips mounted on the head substrate to increase the printing density.

[0007]

In order to achieve this technical object, the present invention provides: "A head substrate and a circuit board are fixed to the upper surface of a heat dissipation plate, and a large number of unit resistors are attached to the upper surface of the head substrate. A print line in which body dots are arranged in a line is formed so as to extend in parallel along one longitudinal side surface of the head substrate, and a large number of each unit resistor dot and each output terminal of a plurality of driving semiconductor chips are formed. While forming a large number of individual leads for electrically connecting the control signal metal wires to each other between each input terminal of each semiconductor chip and each control signal wiring pattern on the upper surface of the circuit board. In a line type thermal print head electrically connected with the above, "in a portion of the upper surface of the head substrate between the print line and the circuit board,
A common lead electrically connected to each of the unit resistor dots via a number of common-side electrodes is formed so that the common lead extends substantially parallel to the print line, and the upper surface of the common lead In the plurality of semiconductor chips, the semiconductor chips are mounted via an insulating layer in a state where the semiconductor chips are arranged in a line, and between the common lead and the common wiring pattern on the upper surface of the circuit board,
A metal wire for common is used to electrically connect each input terminal of each semiconductor chip and a metal wire for control signal connecting each wiring pattern for control signal on the circuit board. "."

[0008]

[Operation] As described above, a common lead that is electrically connected to each unit resistor dot via a number of common-side electrodes on a portion of the upper surface of the head substrate between the print line and the circuit board. Is formed so that the common lead extends substantially parallel to the print line, and by mounting a plurality of semiconductor chips on the upper surface of the common lead via an insulating layer, among the upper surfaces of the head substrate,
The lower part of each semiconductor chip can be used for forming a common lead, and the formation of the common lead between one longitudinal side surface of the head substrate and the print line as in the conventional case is omitted. Therefore, the print line can be brought close to one longitudinal side surface of the head substrate, and the width dimension of the common lead can be greatly increased. The voltage drop can be significantly reduced by connecting the common lead to each unit resistor dot through a large number of common-side electrodes, so that the voltage can be made uniform for each unit resistor dot. is there.

Further, each control signal for connecting each input terminal of each semiconductor chip and each control signal wiring pattern on the circuit board between the common lead and the common wiring pattern on the upper surface of the circuit board. By electrically connecting the common metal wires to each other in the portions between the metal wires for common use, the mutual distances in the respective semiconductor chips are arranged at the portions between the respective semiconductor chips in common. Since it can be made much narrower than when it is provided, the number of semiconductor chips that can be provided in a line along the print line can be increased.

[0010]

Therefore, according to the present invention, the printing characteristics of the line type thermal print head can be reduced in the common lead and the voltage can be made uniform for each unit resistor dot. It is possible to surely improve, and it is possible to improve the printing density by increasing the number of driving semiconductor chips, and there is an effect, and moreover, outside the both ends of the printing line, as in the conventional case,
Since it is not necessary to dispose both ends of the common lead and the length can be shortened, there is an effect that the size and weight can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings of FIGS. In this figure, reference numeral 1 denotes a heat sink made of metal such as aluminum, and a ceramic head substrate 2 and a circuit board 3 with a connection socket 3a are provided on the upper surface thereof.
They are fixed in a substantially parallel state with an adhesive or the like.

A print line 4 having a large number of unit resistor dots 4a arranged in a line is formed on the upper surface of the head substrate 2 adjacent to one longitudinal side surface 2a opposite to the circuit board 3. Is formed so as to extend in parallel along one longitudinal side surface 2a of the head substrate 2, and a wide common lead 5 is formed on a portion of the upper surface of the head substrate 2 closer to the other longitudinal side surface 2b on the side of the circuit board 3. 4 is formed so as to extend in parallel with the insulating layer 6 on the upper surface of the common lead 5.
Is formed so that a portion of the common lead 5 from the other longitudinal side surface 2a is exposed, and on the upper surface of the insulating layer 6,
A plurality of driving semiconductor chips 7 are mounted by arranging the semiconductor chips 7 so that the print lines 4 are arranged substantially in parallel in a line.

Further, in the portion between the print line 4 and the common lead 5 on the upper surface of the head substrate 2, the semiconductor chip 7 is formed from one end of each unit resistor dot 4a in the print line 4. A plurality of individual leads 8 extending in the same direction, and a plurality of common-side electrodes that electrically connect the other end of each unit resistor dot 4a in the print line 4 to the common lead 5. 9 is formed.

The individual leads 8 and the output terminals 7a of the semiconductor chips 7 are electrically connected by wire bonding with the individual metal wires 10, while the individual leads of the semiconductor chips 7 are connected. Input terminal 7b
And the various control signal wiring patterns 11 on the circuit board 3 are electrically connected by wire bonding with the control signal metal wire 12.

Further, between the common lead 5 and each common wiring pattern 13 on the circuit board 3, each input terminal 7b on each semiconductor chip 7 and each control signal wiring pattern 11 on the circuit board 3 are provided. Electrical connection is made by wire bonding with the common metal wire 14 in the region between the control signal metal wires 12 that connect to each other.

The portions of the semiconductor chips 7 and the metal wires 10, 12, 14 are packaged with synthetic resin 15. As described above, a common that is electrically connected to each unit resistor dot 4 a via a large number of common-side electrodes 9 on a portion between the print line 4 and the circuit board 3 on the upper surface of the head substrate 2. The lead 5 is formed so that the common lead 5 extends substantially parallel to the print line 4, and a plurality of semiconductor chips 7 are mounted on the upper surface of the common lead 5 with the insulating layer 6 interposed therebetween. Of the upper surface of the head substrate 2, the lower portion of each semiconductor chip 7 can be used for forming the common leads 5, and the head substrate B can be formed as in the conventional case shown in FIGS. Since it is possible to omit the formation of the common lead D between the longitudinal one side surface B1 and the print line C, the print line 4 is brought close to the longitudinal one side surface 2a of the head substrate 2 and the dimension T therebetween is set. It is possible to significantly narrow.

Moreover, since the width W of the common lead 5 can be greatly increased as shown in the drawing, the voltage drop along the longitudinal direction of the common lead 5 can be remarkably reduced. By substantially connecting the common leads 5 to the unit resistor dots 4a through the multiple common side electrodes 9, it is possible to achieve uniform voltage for the unit resistor dots 4a.

Further, between the common lead 5 and the common wiring pattern 13 on the upper surface of the circuit board 3,
In the portion between each control signal metal wire 12 that connects each input terminal 7b of each semiconductor chip 7 and each control signal wiring pattern 11 of the circuit board 3, a common metal wire 14 electrically serves. By making the connection, the space dimension S between the semiconductor chips 7 can be made much narrower than that in the case where the common metal wire 13 is arranged at a portion between the semiconductor chips 7. The number of semiconductor chips 7 that can be provided in a line along the print line 4 can be increased.

Moreover, it is not necessary to dispose both end portions D1 and D2 for the common lead D outside the left and right end portions of the print line 4 as in the conventional case shown in FIGS. The length of the head substrate 2 can be shortened, and the thermal print head can be reduced in size and weight.

[Brief description of drawings]

FIG. 1 is a plan view of a thermal print head according to an exemplary embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II of FIG.

FIG. 3 is an enlarged plan view of a main part of the thermal print head according to the embodiment of the present invention.

FIG. 4 is an enlarged perspective view of a main part of the thermal print head according to the embodiment of the present invention.

5 is a sectional view taken along line VV of FIG.

6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is a plan view of a conventional thermal print head.

FIG. 8 is an enlarged plan view of a main part of a conventional thermal print head.

9 is a sectional view taken along line IX-IX in FIG. 7.

[Explanation of symbols]

 1 heat sink 2 head substrate 3 circuit board 4 printing line 4a unit resistor dot 5 common lead 6 insulating layer 7 semiconductor chip 7a semiconductor chip output terminal 7b semiconductor chip input terminal 8 individual lead 9 common side electrode 10 individual metal wire 11 Control Signal Wiring Pattern 12 Control Signal Metal Wire 13 Common Wiring Pattern 14 Common Metal Wire

Claims (1)

[Claims] 1. A head substrate and a circuit board are fixed to an upper surface of a heat dissipation plate, and a print line in which a large number of unit resistor dots are arranged in a line on the upper surface of the head substrate has a longitudinal side surface of the head substrate. It is formed so as to extend in parallel along
While forming a large number of individual leads that electrically connect between each of the plurality of unit resistor dots and each of the output terminals of the plurality of driving semiconductor chips, each of the input terminals of each of the semiconductor chips and the In a line-type thermal printhead in which a control signal wiring pattern on the upper surface of a circuit board is electrically connected by a control signal metal wire, the print line and the circuit on the upper surface of the head substrate A common lead, which is electrically connected to each of the unit resistor dots via a number of common-side electrodes, is formed at a portion between the substrate and the unit resistor dot so that the common lead extends substantially parallel to the print line. Then, the plurality of semiconductor chips are mounted on the upper surface of the common lead with the respective semiconductor chips arranged in a line via an insulating layer, while Between the common lead and the common wiring pattern on the upper surface of the circuit board, each control signal metal wire for connecting each input terminal of each semiconductor chip and each control signal wiring pattern of the circuit board. The structure of the line-type thermal print head is characterized in that it is electrically connected with a common metal wire at a portion between them.