JPH0575592B2 - - Google Patents

Description

[Detailed description of the invention] (b) Industrial application fields The present invention relates to a thermal head.

(b) Prior Art As a thermal head using a flexible substrate, the one shown in FIG. 6 is known. 21
1 is a thermal head board, which has a heating resistor 23, a common electrode 24, individual electrodes (not shown), and a connecting terminal 2 on an insulating substrate 22 made of alumina ceramic or the like.
5,...,25 are formed, and the driving IC26,...,
26 are arranged in a row. Heat generating resistor 23
A common electrode 24 extends in the longitudinal direction of the insulating substrate 22, and the common electrode 24 commonly conducts electricity to the heating resistor 23. Both ends of the common electrode 24 serve as connection terminals 24a, 24a.

The individual electrodes individually energize the heating resistor 23 and are wire-bonded to the driving IC 26, respectively. Further, the driving IC 26 is also wire-bonded to the connection terminal 25. Connection terminal 25
are assigned to each drive IC 26 in a predetermined number, and each drive IC 26 independently
For example, DI (data in), DO (data out),
It will have connection terminals such as V _DD and GND.

The edge portion 31a of the flexible substrate 31 is placed over the connection terminals 24a and 25. The flexible substrate 31 has conductor patterns (not shown) that connect and conduct the connection terminals 24a and 25, respectively.
is formed. In addition, the flexible substrate 31
is reinforced by a reinforcing plate 32, and this reinforcing plate 3
2 is attached with a connector (not shown) for connecting the flexible substrate 31 to the outside.

The flexible substrate edge 31a is secured to the thermal head substrate 2 by the silicone rubber 36 of the cover 35.
1. This cover 35 has screws 37,
..., 37 (only two at both ends are shown) are attached to the heat sink 30, and these screws 37, ..., 37
Due to the tightening force, the flexible board edge 31a
A pressing force of the thermal head substrate 21 is generated. Further, this cover 35 has a function of protecting the driving IC 26. In addition, 35a and 33 are screws 3
The insertion hole 7, 30a, is a female screw hole into which a screw 37 is screwed.

(c) Problems to be Solved by the Invention On the flexible substrate 31, there are
A conductor pattern is formed to connect the ICs 26, but this conductor pattern differs depending on the model. Additionally, the number of connector pins and the pitch between the pins vary depending on the model. For this reason, artwork and molds had to be produced for each model, which resulted in the problem of increased labor and time and increased development costs.

This invention has been made in view of the above, and aims to provide a thermal head that can reduce development costs.

(d) Means and operation for solving the problems In order to solve the above problems, the thermal head of the present invention includes a support plate, a support plate placed on the support plate,
an insulating substrate provided with a heating resistor, an electrode for energizing the heating resistor, a connection terminal for external circuit connection, and a plurality of driving circuit elements for driving the heating resistor on its surface; a flexible circuit board having a conductor pattern consisting of a connecting terminal portion that connects and conducts with the connecting terminal and a connecting portion with pin holes that are integrally connected to the connecting terminal portion; and the support plate for reinforcing the flexible circuit board. A reinforcing plate placed on the top and having a pin hole, and a cover for press-contacting the connecting terminal portion of the flexible circuit board to the connecting terminal of the insulating board, wherein the insulating board is provided with a reinforcing plate having a pin hole, and a cover for press-contacting the connecting terminal portion of the flexible circuit board to the connecting terminal of the insulating board. A conductor pattern that commonly connects the same terminals is provided, the conductor pattern is integrally connected to the connection terminal, and the connection terminals are collectively formed at appropriate locations on the insulating substrate, so that the width of the flexible circuit board is reduced. The connection terminal part of the flexible circuit board has a width approximately equal to that of the connection terminal in the long side direction of the insulating board, the pin holes of the flexible circuit board and the reinforcing plate are arranged at equal pitches, and a predetermined number or more of pin holes are provided, and the connection terminal part of the flexible circuit board has the width as described above. are provided at positions corresponding to the connection terminals of the insulating substrate, and the connection terminal portions and the connection portions with equally spaced pin holes are connected by a conductor pattern that changes depending on the model.

In the thermal head of the present invention, a conductor pattern is provided on the insulating substrate to commonly connect the same terminals of each drive circuit element, and this conductor pattern is integrally connected to the connection terminal, and the connection terminal is placed at a suitable location on the insulating substrate. Since the flexible substrate is formed all together, the flexible substrate is also miniaturized, and the conductor pattern on this flexible substrate is naturally limited. In addition, the pin holes of the flexible circuit board and the reinforcing board are arranged at equal pitches, a predetermined number or more of pin holes are provided, and the connection terminal part of the flexible circuit board is provided at a position corresponding to the connection terminal of the insulating board. Since the connection parts with equally spaced pin holes are connected using a conductor pattern, the conductor pattern around the pin holes can be used as a common one, reducing the number of parts that need to be changed for each model, reducing development effort and time. can be done. Furthermore, as long as the pin pitch is suitable, a connector with any number of pins can be used without changing the mold, as long as the number of pin holes is within the range.

(E) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

In FIG. 1, a flexible substrate 11 is connected to a reinforcing plate 12.
It is a perspective view in a state in which it is glued on top and the insertion holes 13, 13a are processed. A conductor pattern 11b for contact conduction is formed on the edge 11a of the flexible substrate 11. In addition, the flexible substrate 11 includes
Conductor pattern 11c for connection with connector pins
are also formed with equal pitch. The arrangement and number of these conductor patterns 11b and 11c are predetermined, and the wiring conductor pattern that connects them (formed in the area surrounded by the two-dot chain line in FIG. 1)
only changes for each model.

The flexible substrate 11 on which the conductor patterns 11b, 11c and a wiring conductor pattern (not shown) are formed is adhered to the reinforcing plate 12, and is formed with a mold to form an insertion hole 13 for attachment and an insertion hole 1 for a connector pin.
3a is processed. Since the position and number of conductor patterns 11c are predetermined, there is no need to change the mold for each model. An extra number of conductor patterns 11c and insertion holes 13a are provided, and the number of pins of the connector can be arbitrarily selected as long as the pitch is suitable.

Now, a thermal head using the flexible substrate 11 will be explained below with reference to FIGS. 2 to 5.

The thermal head substrate 1 has a conductor pattern formed on an insulating substrate 2 made of alumina ceramic or the like, and has a common electrode 4, a connection terminal 5, an individual electrode 7, and a ground electrode 8. Furthermore, drive ICs 6, . . . , 6 are arranged in rows on the insulating substrate 2 (see FIG. 2).

Looking more closely, the connection terminals 5 are arranged in a row at the center portion 2a of the rear edge of the insulating substrate. The number of connection terminals 5 is very small compared to the conventional one, but this is because the wiring, which was conventionally done on the flexible substrate side, is now done on the conductor pattern 5a on the insulating substrate 2. A portion of these conductor patterns 5a is also shown in FIG. 5, and is bonded to a pad 6a of a corresponding driving IC 6 by a wire W. Note that since the present invention does not involve the connection circuit itself of the driving IC 6 as a main part, a detailed explanation thereof will be omitted.

The conductor pattern 5a is connected to the connection terminal 5, and DI, DO, LA (latch), CLK (clock), _VDD , and STR (strobe) 1 to 4 are assigned. In addition, the drive IC6 located in the center,
Since it is difficult to wire bond directly to the ground electrode 8 due to the arrangement, a dedicated ground terminal 5 (GND) is provided for each of the terminals 6 and 6.

The common electrode 4 is formed along the periphery of the insulating substrate 2, and its ends reach the rear central portion 2a of the insulating substrate to serve as connection terminals 4a, 4a. Connection terminal 4a
are three conductor patterns 4 having the same shape as the connecting terminal 5.
b is assigned, and silver paste 4c is applied overlappingly to reduce the resistance value.

Reference numeral 7 denotes an individual electrode, and its tip portion 7a is arranged so as to mesh with the comb tooth portion 4d of the common electrode 4.
The base ends 7b of the individual electrodes 7 are drawn out to the vicinity of the driving IC 6 and bonded to the corresponding pads 6b with wires W. In addition, the individual electrode 7
The one that is pulled out diagonally is the drive IC6,
This is to provide an interval of 6.

A thick-film heating resistor 3 is formed on the common electrode comb tooth portion 4d and the individual electrode tip portion 7a. A portion of the heating resistor 3 sandwiched between the comb teeth portions 4d corresponds to one dot. Of course, the heating resistor 3 can also be made into a thin film, and the design can be changed as appropriate.

The ground electrodes 8, 8 extend in the longitudinal direction of the insulating substrate along the inside of the common electrode 4 from the rear center portion 2a of the insulating substrate toward both ends 2b, 2b, respectively. The connection terminal 8a of the ground electrode 8 is assigned conductor patterns 8b, . Both ground electrodes 8, 8 are connected to the GND pads of the drive ICs 6, ..., 6, excluding the two drive ICs 6, 6 in the center.
Wire bonded. In addition, drive IC6,
..., 6 are coated with resin 9, and wires W, ...,
It is protected by insulation together with W (see Figures 2 and 3).

The thermal head board 1 is mounted on a heat sink 10. At this time, the thermal head board 1 is bonded only at the center part 10c of the heat sink, but this is because
This is because the thermal expansion coefficients of the thermal head substrate 1 and the heat sink 10 are different, and the structure is such that the thermal head substrate 1 and the heat sink 10 are unlikely to warp even when the temperature rises.

The flexible substrate 11 and the cover 15 are fixed to the heat sink 10 by screws 17a (see also FIG. 3). The screw 17a is inserted into the insertion hole 1 of the cover 15.
5a, and is inserted through the insertion hole 13 and screwed into the female screw hole 10a of the heat sink 11. At this time, the silicone rubber 16 on the bottom of the cover 15 is attached to the flexible board edge 11.
a is pressed against the center portion 2a of the rear edge of the insulating substrate. The tightening torque of the screws 17a, 17a is controlled so that a uniform contact and conduction state between the conductor pattern 11b of the flexible board edge 11a and the connection terminals 4a, 5, 8a is obtained.

Large-diameter insertion holes 15b are bored at both ends of the cover 15, into which a spacer 18 is inserted, and a screw 17b is screwed into the female screw hole 10b of the heat sink through the spacer 18 (see also FIG. 4). reference).
The head of the screw 17b is in contact with the cover 15, but the tightening force of the screw 17b is solely due to the spacer 18, and the screw 17b is simply attached to the cover 15.
The structure is such that the end portion of 5 is prevented from lifting up. This is because if the end portion of the cover 15 is completely fixed to the heat sink 10, there is a risk that the entire cover may warp due to the difference in the coefficient of thermal expansion of each member.

In the above embodiment, the connection terminals 5 are grouped together at the rear edge central portion 2a of the insulating substrate, but the location where the connection terminals are grouped is not limited to this, and the design can be changed as appropriate.

(f) Effects of the Invention As explained above, in the thermal head of the present invention, the conductor pattern connecting the driving elements is connected in common to the same terminals of each driving circuit element, and the thermal head board side In addition, pin holes for connectors on the flexible circuit board and the auxiliary board are provided at equal pitches, and extra pin holes are provided for the connectors, and the connecting terminals of the flexible circuit board are made to correspond to the connecting terminals of the insulating circuit board. It is characterized by connecting the connecting part with equally spaced pin holes using a conductive pattern, and using a common conductive pattern around the pin holes, so there is less need to change the flexible board and auxiliary board for each model. Therefore, since the mold does not need to be changed even when changing the model, the development cost of the flexible substrate can be reduced, and the overall advantage is that the thermal head can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a flexible substrate according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of a thermal head using the flexible substrate, and FIG. 3 is a vertical cross-sectional view of the thermal head. , FIG. 4 is a partially cutaway rear view of the main parts of the same thermal head, FIG. 5 is a plan view of the main parts of the thermal head board of the same thermal head, and FIG. 6 is a diagram showing the conventional flexible board. FIG. 3 is an exploded perspective view of the thermal head used. 3: Heat generating resistor, 6: Drive IC, 11: Flexible board, 11b, 11c: Conductor pattern,
13a: insertion hole, 14: connector, 14a: pin.

Claims (1)

[Scope of Claims] 1. A support plate, and a heat generating resistor, an electrode for energizing the heat generating resistor, and a connecting terminal for external circuit connection are formed on the surface of the support plate, and the above-mentioned It consists of an insulating substrate provided with a plurality of drive circuit elements that drive the heat generating resistor, a connecting terminal part that makes contact with the connecting terminal, and a connecting part with a pin hole that is integrally connected to the connecting terminal part. A flexible circuit board having a conductor pattern, a reinforcing plate placed on the support plate and having pin holes for reinforcing the flexible circuit board, and a connecting terminal portion of the flexible circuit board being press-connected to a connecting terminal of an insulating board. In the thermal head, a conductor pattern is provided on the insulating substrate to commonly connect the same terminals of each of the drive circuit elements, and the conductor pattern is integrally connected to the connection terminal, and The connecting terminals are collectively formed at appropriate locations on the insulating board, the width of the flexible circuit board is approximately the width that the connecting terminals occupy in the long side direction of the insulating board, and the pin holes of the flexible circuit board and the reinforcing plate are arranged at equal pitches. , a predetermined number or more of pin holes are provided, and a connection terminal portion of the flexible circuit board having the width is provided at a position corresponding to the connection terminal of the insulating substrate, and this connection terminal portion and the connection portion with pin holes of the same pitch are provided. A thermal head characterized by connecting the two with a conductor pattern that changes depending on the model.