JP2676026B2 - Thermal 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 thermal head used in video printers, label printers, etc., which enables miniaturization of a printing mechanism.

[0002]

2. Description of the Related Art A conventional thermal head is a flat type thermal head as shown in FIG. 4, in which an alumina substrate (2) and a glass epoxy substrate (8) are mounted on a heat sink (1) made of aluminum or the like. On the alumina substrate (2), the heating resistor (4) and the driving I
An IC-mounted thermal head on an alumina substrate (FIG. 4-a) on which C (5) is installed, a heating resistor (4) on the alumina substrate (2), and a glass epoxy substrate (8) driving I
IC on glass epoxy substrate with C (5) separated
An on-board thermal head (FIG. 4-b) was used, and the heating resistor (4) and the driving IC (5) were electrically connected to each other by wire bonding (6).
The driving IC (5) is covered with a protective resin (7), and a connector (9) is provided on one side of the glass epoxy substrate (8). Also, the TA including the alumina substrate (2) and the glass epoxy substrate (8) installed on the heat sink (1) and the driving IC (5)
The TAB type thermal head (FIG. 4-c) electrically connected with the B tape (10) was used.

However, when miniaturizing various devices, a thermal head having a small size in the traveling direction of the thermal paper is required, and therefore, an end face type thermal head as shown in FIG. 5 is used. . A corner of a heat sink (1) made of aluminum or the like is removed, an alumina substrate (2) having a curved tip is provided on the corner, and a heating resistor (4) is placed on the alumina substrate (2). The driving IC (5) is provided on one side surface of (2), the heating resistor (4) and the driving IC (5) are electrically connected by wire bonding (6), and the driving IC (5). Curved type thermal head in which a glass epoxy substrate (8) is provided on a heat sink (1) on the same side surface as that (Fig. 5-a).
And the alumina substrate (2) on the tip of the heat sink (1)
, A heating resistor (4) is placed thereon, and a glass epoxy substrate (8) is attached to one side surface of the heat sink (1).
The wiring part on the alumina substrate (2) and the wiring part on the glass epoxy substrate (8) were electrically connected by a TAB tape (10) equipped with a driving IC (5). A TAB type thermal head (Fig. 5-b) was used.

[0004]

In the case of the conventional flat type and end face type thermal heads, the former type has the alumina substrate (2) and the glass on the large surface of the heat sink (1) as shown in FIG. Since the epoxy substrate (8) is provided, it has a wide width, and particularly when using the ink ribbon, it is difficult to reduce the size of the ink ribbon, so that the printing mechanism is unavoidably increased in size.

In the latter case, first, in FIG. 5A, one corner of the heat sink (1) is removed, and a curved type thermal head is provided in which an alumina substrate (2) having a curved tip is provided. However, since it requires film formation and film processing on the curved surface, the processing is troublesome, mass productivity is poor, and the cost is high. In addition, the structure had poor heat dissipation and was easy to store heat.

Further, the wiring portion on the alumina substrate (2) and the wiring portion on the glass epoxy substrate (8) of FIG. 5B are electrically connected by the TAB tape (10) equipped with the driving IC (5). In the TAB type thermal head connected to, since the TAB tape (10) is required in addition to the glass epoxy substrate (8), the number of parts is increased and the cost is high. The manufacturing method has become complicated, for example, a solder electrode is required to attach it to each substrate.

An object of the present invention is to improve the productivity and reduce the cost by reducing the width of the printing portion of the thermal head and simplifying the manufacturing process, thereby enabling better printing. There is.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and an object thereof is to provide a so-called end face type thermal head having the following structure.

(1) A thermal head in which a substrate on which a heating resistor is formed and a circuit board on which a driving IC for energizing the heating resistor is mounted are provided on the same end face of a heat sink. The circuit board is a flexible fill head, and the circuit board is made of a flexible film and is bent along the side surface of the heat sink at one end of the heat sink and fixed to the side surface. The thermal head is characterized by being.

[0010]

[0011]

In the thermal head having the above structure, the electrical connection between the substrate on which the heating resistor is formed and the circuit board on which the driving IC is mounted is performed by wire bonding.
This reduces the number of electrical connections compared to conventional devices of this type. The reduction in the number of connecting portions greatly improves the productivity of the thermal head, and the amount of gold wire used for the wire bonding process is reduced, which contributes to cost reduction. Further, due to the reduction of the connection portion, the number of defective connection points such as so-called loose contacts is reduced, and the performance of the thermal head can be improved.

[0013]

1 is a sectional view of a thermal head of the present invention, and FIG. 2 is a schematic perspective view of the thermal head of the present invention.

As shown in this figure, the present invention
On one end face of the heat sink (1) such as aluminum,
A thin film substrate such as an alumina substrate (2) is installed. Na)
Since it is configured to be narrower than the width of one end surface of the heat sink (1), a circuit board made of a flexible film such as a flexible cable (3) is provided on the remaining end surface of the heat sink (1). And the flexible cable (3)
Has a larger area than the rest of the end surface of the heat sink (1) described above, and thus protrudes from the end surface. However, since the board is a flexible cable, it is soft, and the part protruding from the end surface can be freely bent. Therefore, the flexible cable board (3) of the heat sink (1) is bent along the side surface in the protruding direction, and the flexible cable board (3) on the side surface is fixed with an adhesive (15) such as double-sided tape or epoxy resin. Has been done.
By performing such a treatment, the free movement of the flexible cable substrate (3) is suppressed, and the printing operation on the end face portion of the heat sink (1) becomes smoother.

As described above, the flexible cable substrate (3) protruding from the end face portion is used at the same time that the one end face portion of the heat sink (1) is used instead of the wide main plane portion. As described above, since it is bent, the printing width can be reduced, and therefore the printing mechanism has a small dimension in the traveling direction of the thermal paper. Therefore, as compared with the conventional TAB type thermal head shown in FIG. 5B, the glass epoxy substrate (8) is unnecessary.

Since the heat generating resistor (4) on the alumina substrate (2) and the driving IC (5) on the flexible cable substrate (3) are installed on the same one end face of the heat sink (1), A wiring section connected to the heating resistor (4) through a lead electrode (12) and a driving IC (5),
Then, the driving IC (5), the metal electrode portion (copper electrode) (13) of the flexible cable substrate (3), the common electrode (1
1) and the metal electrode part (13) of the flexible cable substrate (3) are electrically connected by wire bonding (6).

That is, unlike the conventional end face type thermal head (FIG. 5), the driving IC (5) is not mounted on the side surface of the heat sink (1), but the end face type head has the same width. The driving IC (5) is installed on the narrow surface. The driving IC (5) is covered with a protective resin (7) to protect the driving IC (5) and the wire bonding (6). And (9) is a connector.

Here, the thickness of the flexible cable substrate (3) installed on one end face of the heat sink (1) is larger than that of the alumina substrate (2) installed on one end face of the same heat sink (1). Have been made significantly smaller. Therefore, the total height of the alumina substrate (2) including the heating resistor (4) is substantially the same as the total height of the flexible cable substrate (3) including the driving IC (5) and the protective resin (7). It does not hinder the passage of the printing paper on its upper surface, and even a considerably thick and hard paper can be freely used for printing.

Further, FIG. 3 shows an example of the flexible cable substrate (3), which is made of a resin such as heat-resistant polyimide and has copper electrodes on the upper and lower surfaces of a flexible base film (16). Metal electrodes, etc. (13)
A two-layer wiring board in which circuit patterns formed on the upper and lower sides of a base film (16) are connected by through holes (17) by forming an overlay (14) on the upper and lower sides of the circuit pattern by forming a circuit pattern by attaching Thus, the flexible cable substrate (3) is configured.

When printing, an ink ribbon is sandwiched between thermal papers, and the thermal papers are pressure-bonded with a platen roller, and on a heating resistor (4) protected by an abrasion resistant film. Characters are printed by thermal transfer of.

[0021]

As described above, according to the present invention, the heat generating resistor (4) and the driving IC (5) can be collectively installed on the one end face of the heat sink (1) having a narrow width. Since the work can be performed on the same surface even in connection work, the workability is improved, and the flexible cable substrate (3) having the driving IC (5) is bent along the side surface of the heat sink (1), By being fixed to the side surface, the widthwise dimension of the printed portion can be reduced, and thereby the printing mechanism can be downsized.
Further, since the substrate on which the heating resistor is formed can be made small, the number of films that can be formed at one time can be increased, and productivity can be improved and cost can be reduced.
Further, by applying such a treatment, the flexibility of the flexible cable can be used to bend along the side surface of the heat sink (1), and at the same time, it is fixed to the side surface of the heat sink (1) with a double-sided tape or an adhesive. By doing so, the flexibility of the flexible cable can be partially eliminated before use, so it is possible to easily connect to an external connector, etc., and it is possible to suppress the extra movement of the flexible cable. Further miniaturization becomes possible.

Then, the wiring portion for energizing the heating resistor (4) on the alumina substrate (2) and the driving IC (5),
The drive IC (5) and the electrode portion of the flexible cable substrate (3) are electrically connected by wire bonding (6), and the number of connection points is reduced as compared with the conventional one, and gold wire is used. Since the amount of use of such expensive materials is also reduced, the manufacturing process is simplified and the cost is reduced.

Further, as compared with the above-mentioned curved surface type thermal head (FIG. 5-a) of the end face type, the heat dissipation is improved,
Good printing with little bleeding is possible. In addition to this, the thickness of the flexible cable substrate (3) installed on one end surface of the heat sink (1) is the same as that of the alumina substrate (2) installed on one end surface of the same heat sink (1).
It is significantly smaller than that. For this,
The total height of the alumina substrate (2) including the heating resistor (4) is the driving IC on the flexible cable substrate (3).
The height is approximately the same as that of (5) and the like, and the printing paper can be smoothly passed on the upper surface thereof.

[Brief description of the drawings]

FIG. 1 is a sectional view of a thermal head according to the present invention.

FIG. 2 is a schematic perspective view of a thermal head of the present invention.

FIG. 3 is a sectional view of a flexible cable substrate of the thermal head of the present invention.

FIG. 4 is a view showing a conventional planar thermal head. (A) is an IC mounted type on an alumina substrate (b) is an IC mounted type on a glass epoxy substrate (c) is a TAB type

FIG. 5 is a view showing a conventional end face type thermal head. (A) is a curved type (b) is a TAB type

[Explanation of symbols]

 1: Heat Sink 2: Alumina Substrate 3: Flexible Cable Substrate 4: Heating Resistor 5: Driving IC 6: Wire Bonding 7: Protective Resin 8: Glass Epoxy Substrate 9: Connector 10: TAB Tape 11: Common Electrode 12: Lead Electrode 13: Metal electrode 14: Overlay 15: Adhesive 16: Base film 17: Through hole

Claims (1)

(57) [Claims] 1. A alumina substrate formed with the heating resistor, and a circuit board mounting the driving IC for energizing the heat generating resistor, Oite brought close separated from each other in the same end face of the heat sink
A thermal head comprising a flexible film, the circuit board being bent along two side faces of the heat sink at one end of the heat sink and fixed to the side faces. And thermal head.