JPH06106757A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a thermal head wherein structure is simplified and miniaturization is achieved without the need for providing an occupied region for a through-hole on a circuit substrate, by forming the through-hole of the circuit substrate in a position under a drive circuit component. CONSTITUTION:A structure wherein a heating resistor 21 of a thermal head 1 is projected is made in such a manner that planes 16 to 20 are continuously formed on a substrate 2. Since the heating resistor 21 and an electrode 22 are easily formed on the planes 16 to 21, productivity of the thermal head 1 becomes high. In this thermal head 1, since a through-hole 7 for connecting printed wirings 6 disposed on the front and rear surfaces of a rigid substrate 4 made of rigid FPC to each other is formed in a position under a driver IC 5, an occupied region for the through-hole 7 is not required to be provided, thereby miniaturizing the rigid substrate 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head having a large number of heating resistors arranged on a substrate.

[0002]

2. Description of the Related Art In a conventional thermal head, a driver I, which is a drive circuit component, is provided with a large number of heating resistors arranged in series on a substrate.
It has a structure in which C (Integrated Circuit) is connected,
A circuit board on which such a driver IC is mounted has, for example, a structure in which printed wirings formed on both the front surface and the back surface are connected via through holes.

[0003]

In the above-described thermal head, the circuit board is miniaturized by forming the printed wiring to be connected by the through hole on both the front and back surfaces. Arranges the driver IC, the printed wiring, and the through hole so that a dead space does not occur.

However, at present, there are demands for miniaturization of various devices, and further miniaturization of the above thermal head is demanded.

The present invention provides a thermal head which has a simple structure and is miniaturized.

[0006]

A circuit board is provided in which a large number of heating resistors are continuously provided on a board, and printed wirings formed on both the front surface and the back surface are connected through through holes. In a thermal head in which a drive circuit component mounted on a printed wiring on the surface is connected to the heating resistor, the through hole of the circuit board is formed at a position below the drive circuit component.

[0007]

Since it is not necessary to provide the area occupied by the through holes on the circuit board, it is possible to obtain a thermal head having a simple structure and a small size.

[0008]

Embodiments of the present invention will be described with reference to FIGS. First, as shown in FIG. 1, the thermal head 1 includes a rigid board F which is a circuit board on the head board 2.
A rigid board 4 of a PC (Flexible Printed Circuit) 3 is arranged in parallel, and a driver IC 5 which is a driving circuit component is mounted on the rigid board 4. In the thermal head 1, the printed wirings 6 formed on both the front surface and the back surface of the rigid substrate 4 are connected via the through holes 7. The through hole 7 is located below the driver IC 5.

More specifically, as illustrated in FIG. 2, the rigid substrate 4 elongated in the main scanning direction of the rigid FPC 3 has a plurality of mounting regions 8 of the driver ICs 5 connected in the vicinity of one edge thereof. A large number of bonding pads 9 that are a part of the printed wiring 6 are continuously provided near the other edge. The printed wiring 6 continuous with the bonding pads 9 extends in the mounting area 8 of the driver IC 5. In this mounting area 8, the printed wiring 6 communicates with the back surface of the rigid substrate 4 through the through hole 7. In addition,
The rigid FPC 3 has a structure in which the rigid substrate 4, the flexible substrate 10, and the rigid substrate 11 are integrally formed, and a large number of through holes 12 and printed wirings 13 are provided on the surface of the rigid substrate 11. Has been.

As illustrated in FIG. 1, the driver IC 5 mounted on the rigid substrate 4 of the rigid FPC 3 has a large number of connection pads 14 continuously provided on its upper surface. These connection pads 14 are connected to the rigid substrate 4
The bonding wire 9 is connected to the bonding pad 9 of FIG.

Here, the head substrate 2 which is elongated in the main scanning direction has flat surfaces 17 and 18 which are inclined on both sides in the sub scanning direction of a high flat surface 16 which is provided at a substantial center in the sub scanning direction. . On both sides of these planes 17 and 18, a plane 19 parallel to the plane 16 and slightly lower and a plane 2 possibly lower.
0 and form. In the thermal head 1, the heating resistor 21 is continuously provided on the high plane 16 in the main scanning direction, and the common electrode 2 is provided on the inclined planes 17 and 18.
2 and the individual electrode 23 are formed. Further, in this thermal head 1, the low flat surface 1 of the head substrate 2 is used.
The terminal part 2 which is a part of the electrodes 22 and 23 on 9 and 20
4 is forming. The connection pads 14 of the driver IC 5 are connected to these terminal portions 24 by bonding wires 15. In this thermal head 1, a glass glaze layer 25 is formed as the lowermost layer on substantially the entire planes 16 to 20 of the head substrate 2, and the surface of the head substrate 2 other than the terminal portions 24 is shielded by a protective film 26. ing.

In the thermal printer 27 using the thermal head 1 having the above-described structure, as shown in FIG. 3, the head substrate 2 and the rigid substrate 4 of the rigid FPC 3 are projected from the heat radiating plate 28. The rigid FPC 3 is mounted in parallel on the flat surface 29, and is mounted on the low flat surface 31 continuous through the flat surface 30 inclined to the high flat surface 29.
The rigid board 11 of FIG. In this thermal printer 27, circuit components such as a capacitor 32 and a connection connector 33 are mounted on the front and back surfaces of the rigid board 11 of the rigid FPC 3, and a printer controller (not shown) is connected to the connection connector 33. It is like this.

In the thermal printer 27, the driver IC 5 mounted on the rigid FPC 3 is potted with a sealing material 34 such as resin, and the sealing material 34 is shielded so as to be continuous with the flat surface 16 of the head substrate 2. The protective cover 35 having the shape described above is attached to the rigid substrate 11 of the rigid FPC 3. Furthermore, this thermal printer 2
7, a platen roller 36 is rotatably supported at a position facing the heat generating resistor 21 of the thermal head 1, and an ink ribbon, a recording medium 37, or the like is provided between the platen roller 36 and the thermal head 1. It forms a transport path.

In such a structure, in the thermal head 1 of the thermal printer 27, the flat surface 16 on which the heating resistor 21 for actually printing on the recording medium 37 is located.
However, the recording medium 37 such as a plastic card can be conveyed in a straight line without being curved because it protrudes from the planes 17 to 20 located in front of and behind it. The structure in which the heating resistor 21 of the thermal head 1 projects in this manner is realized by the flat surfaces 16 to 20 continuously formed on the head substrate 2. Such a flat surface 16 to 20
Since it is easy to form the heating resistor 21 and the electrodes 22 and 23 on it, the thermal head 1 has good productivity.

In the thermal head 1, since the through holes 7 for connecting the printed wirings 6 on the front and back surfaces of the rigid substrate 4 of the rigid FPC 3 are formed below the driver IC 5, the through holes 7 for the through holes 7 are formed. The rigid substrate 4 is downsized so that the occupied area is not required.

Here, in the thermal head 1 as described above, the number of connections between the heating resistors 21 and the driver ICs 5 that need to be individually operated is inevitably large, and therefore a plurality of driver ICs 5 are mainly used here. The connection pads 14 are continuously provided in the scanning direction so that the connection pads 14 are adjacent to the terminal portions 24 of the head substrate 2. However, when the driver ICs 5 continuously provided in this way are displaced in the main scanning direction or the like due to a temperature change of the circuit board or the like. The yield of wire bonding will be reduced.

Therefore, in the thermal head 1 of the present embodiment, the rigid FPC 3 which is slightly deformed due to temperature change and the like.
By mounting the driver IC 5 on the rigid substrate 4, the wire bonding between the connection pad 14 of the driver IC 5 and the terminal portion 24 of the head substrate 2 can be favorably performed. Furthermore, such rigid FPC
Since the rigid board 4 of No. 3 is also strong in terms of strength, it is possible to reduce the error in the mounting position of the driver IC 5, and the connection pad 1 of the driver IC 5 thus mounted.
Wire bonding between the bonding pad 4 and the bonding pad 9 of the rigid substrate 4 can be satisfactorily performed. In this way, it is also possible to integrally form the rigid substrate 4 on which the driver IC 5 is mounted and the head substrate 2 on which the heating resistor 21 is provided in series.

Further, in the thermal printer 27 illustrated in this embodiment, the heat dissipation plate 28 is formed in such a manner that the high flat surface 29, the inclined flat surface 30 and the low flat surface 31 are successively connected, and the thermal head 1 is placed on the high flat surface 29. Place it on Rigid F
By arranging the flexible substrate 10 and the rigid substrate 11 of the PC 3 on the planes 30 and 31 sequentially, the rigid FP
The capacitor 32 and the like mounted on the rigid substrate 11 of C3 are prevented from interfering with the conveyance path of the recording medium 37. Then, in order to secure the wiring between the rigid substrates 4 and 11 arranged on the planes 29 and 31 having different heights in this way, here, the rigid substrates 4 and 11 and the flexible substrate 1 are previously prepared.
The rigid FPC 3 in which 0 and 0 are integrally formed is used.

As described above, the heat dissipation plate 38 which does not interfere with the condenser 32 and the like in the conveyance path of the recording medium 37 is as follows.
As shown in FIG. 4, in addition to the heat radiating plate in which the high plane and the low plane are formed in a stepwise manner, the heat radiating plate in which the high plane and the inclined plane are formed (neither is shown), etc. Also, an L-shaped heat dissipation plate 38 or the like can be implemented. In the thermal printer 39 using such a heat dissipation plate 38, the head substrate 2 and the rigid substrate 4 are arranged side by side on the upper end surface 40 of the heat dissipation plate 38, and the rigid substrate 11 is provided on the lower side surface 41.
The occupying area can be reduced by arranging.

Further, in the thermal head 1 of this embodiment, the productivity is improved by mounting the driver IC 5 on the rigid substrate 4 of the rigid FPC 3 as described above, but as shown in FIG. And driver I
The C5 is mounted on an ordinary rigid circuit board 42, and the printed wiring 44 formed from the front surface to the back surface of the circuit board 42 through the through holes 43 is used as the printed wiring 47 on the base film 46 of the separate FPC 45. It is also possible to connect with the solder 48.

[0021]

As described above, according to the present invention, since the through hole of the circuit board is formed at the position under the drive circuit component, it is not necessary to provide the area occupied by the through hole on the circuit board, so that the structure is simple. With this, it is possible to obtain a thermal head that is downsized.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a thermal head according to an embodiment of the present invention.

FIG. 2 is a plan view showing a rigid FPC which is a circuit board.

FIG. 3 is a vertical sectional side view showing a thermal printer.

FIG. 4 is a vertical sectional side view showing a modified example of the thermal printer.

FIG. 5 is a vertical sectional side view showing a modified example of the circuit board.

[Explanation of symbols]

 1 Thermal Head 2 Board 4, 42 Circuit Board 5 Drive Circuit Parts 6,44 Printed Wiring 7,43 Through Hole 21 Heating Resistor

[Procedure amendment]

[Submission date] October 15, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Kushida 6-78 Minamimachi, Mishima City, Shizuoka Prefecture, Tokyo Institute of Technology Research Institute

Claims (1)

[Claims] 1. A circuit board in which a large number of heating resistors are continuously provided on a board and printed wirings formed on both the front surface and the back surface are connected through through holes, and a printed wiring on the front surface of the circuit board is provided. A thermal head in which a drive circuit component mounted above is connected to the heating resistor, wherein the through hole of the circuit board is formed at a position below the drive circuit component.