JPH0499653A - Thermal head - Google Patents

Abstract

PURPOSE:To prevent an irregularity in local heat transfer of a board and a heat dissipation plate and to improve printing quality by adhesively integrating a heat dissipation member of a curved shaped recessed at a securing surface side or flat plate shape. CONSTITUTION:A heat generating resistor array 13 is formed near one end on a head board 12, a driving circuit 14 is mounted near its opposite side end to the row 13, and inputs data to be printed and various control signals. The board 12 is secured through a rectangular heat dissipating plate 15 made of a metal material having excellent heat conductivity such as aluminum and an adhesive layer 17 made of adhesive or self-adhesive.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a thermal head.

[Prior Art] FIG. 8 is a cross-sectional view illustrating the manufacturing process of a typical conventional thermal head 1. To thermal...I do 1 is,
A head substrate 3 made of an electrically insulating material such as ceramic is provided with a heat generating resistor array 2 formed on one side surface, and a drive circuit 4 for driving the heat generating resistor array 2 is mounted on the head substrate 3. Then, it is covered with a protective layer 5 of synthetic resin. The drive circuit 4 is electrically connected to the heat generating resistor array 2, and the signals necessary to control the drive circuit 4 are sent to the head substrate 3.
It is supplied from an external wiring board 6 connected to. A heat dissipation plate 7 made of a material with good thermal conductivity such as aluminum is fixed to the surface of the head substrate 3 opposite to the surface on which the heat generating resistor array 2 is formed via an adhesive layer 8. Ru.

To fix the head substrate 3 and the heat sink 7 together, a pressing piece 910 is used as shown in FIG. 8. The pressing piece 9 is connected to the drive circuit 4 of the head substrate 3 and the heating resistor array 2.
The pressure is applied relatively close to the central position of the head substrate 3, avoiding the relatively peripheral edge of the head substrate 3 where the head substrate 3 is formed. The pressing piece 10 presses a position on the heat sink 7 that corresponds to the position pressed by the pressing piece 9 .

On the other hand, the shape of the heat sink 7 is almost a rectangular parallelepiped, and the heat sink 7
It is known that a curved amount dl (for example, 50 μm) as shown in FIG. 8 occurs for a total length Ll (for example, 30 mm) of When it is fixed to the head board 3,
The layer thickness of the adhesive layer 8 is different between the vicinity of the central position and the peripheral portion. In recent years, the printing speed of thermal heads has increased, and it is necessary to quickly and evenly release the heat generated in the heat generating resistor array 2 to the heat sink plate 7 along the longitudinal direction of the heat generating resistor array 2.

However, in the above conventional example, due to variations in the layer thickness of the adhesive layer 8, variations occur in the amount of heat generated in the heat generating resistor array 2 and the heat conduction to the heat dissipation plate 7.
The temperature of the head substrate 3 undesirably increases on the side relatively close to the peripheral edge.

As a result, even in portions of the heating resistor array 2 where printing is not necessary, for example, thermal recording paper or the like is thermally colored, resulting in a significant deterioration of printing quality.

The curved state of the heat dissipation plate 7 described above is not limited to the one shown in FIG. 8 [21], but it is known that various curved shapes occur as shown in FIGS. However, as mentioned above, the print quality will deteriorate.

[Problems to be Solved by the Invention] In the conventional example as described above, there is a problem in that the quality of thermal printing is significantly deteriorated due to variations in the curved shape of the heat sink 7.5 The object of the present invention is to It is an object of the present invention to provide a thermal head that solves the above-mentioned technical problems and significantly improves the quality of thermal printing.

[Means for Solving the Problems] The present invention provides a thermal head in which a heat dissipating member is attached to a substrate provided with an array of heating resistors, which has a curved shape concave on the side to which the substrate is fixed, or This is a thermal device made by bonding and integrating a flat plate-shaped heat dissipating member.

[Function] The thermal throat of the present invention is formed by forming the fixed surface of the heat dissipating member facing the substrate into a concave curved shape or a flat plate shape,
The substrate on which the heating resistor is formed is adhered to the fixing surface of the heat dissipating member by pressing a position corresponding to the vicinity of the center of the fixing surface via an adhesive layer. As a result, if the surface of the board facing the heat dissipation member is curved in a convex manner in the same direction as the fixed surface of the heat dissipation member, the heat dissipation member and the electrically insulating board are bonded with the same layer thickness over their entire length. It is fixed with a layer of agent.

In addition, if the substrate is flat or curved in the opposite direction to the curved direction of the heat dissipation member, by pressing and bonding them together, the substrate and the heat dissipation member are deformed into a flat plate shape,
Again, they are fixed via an adhesive layer having a uniform thickness over their entire length. Therefore, it is possible to prevent local variations in heat conductivity between the substrate and the heat dissipation plate, and to prevent the heat generated by the heating resistor from being accumulated undesirably and causing undesired thermal printing. It is possible to improve the quality of thermal printing.

[Embodiment] FIG. 1 is a sectional view illustrating the operation of an embodiment of the present invention, FIG. 2 is a perspective view of a thermal head 11 of an embodiment of the present invention, and FIG. It is a sectional view taken along the section line m-■ in the figure. The thermal head 11 is made of an electrically insulating material such as alumina ceramic and has a thickness tl (
For example, 0°635mm), width Wl (for example, 10mm
>, and includes a head base vi12 formed in the shape of a rectangular parallelepiped with a length L2 (for example, 30 mm). A resistor row 13 is formed, and a drive circuit 14 for selectively driving the heat-generating resistor row 13 to generate heat is located near the end opposite to the heat-generating resistor row 13 along the length direction of the upper substrate 12. This drive circuit 14
Data to be printed and various control signals are input through an external wiring board 15 connected to the hendo board 12.

The upper substrate 12 is made of a rectangular plate-shaped heat dissipation plate 16 with a thickness t2 (for example, 2.0 mm or less) made of a metal material with good thermal conductivity such as aluminum, and an adhesive or adhesive. They are fixed to each other through an adhesive layer 17 made of the same material.

FIG. 4 is a process diagram illustrating the process of manufacturing the thermal head 11. In step a1 of FIG. 4, the heating resistor array 13 and the drive circuit 14 as shown in FIGS. 2 and 3 are
A head board 12 is manufactured to which the external wiring board 15 is connected. The heat sink 16 having the above-described shape is formed by a known technique such as press molding or die casting.

It is known that the head substrate 12 is curved concavely or convexly by a curved amount d2 relative to the length L2, as shown in FIG. 1(1). On the other hand, when the heat dissipation plate 16 is manufactured by press molding, for example, the shape of the mold used for press molding is deformed so that the heat dissipation plate 16 has a curved amount with respect to the length L3, as shown in FIG. 1(1). d3 (50 μm as an example)
) It can be formed to have the following constant curved shape.

When the head substrate 12 and the heat dissipation plate 16 are concavely curved in the same direction as shown in the first figure, they are made to face each other and the head substrate 12 is placed on the concave support surface 18 of the heat dissipation plate 16.
The opposite surface to the surface on which the heating resistor array 13 is formed is made to face, and these are bonded to each other via an adhesive layer 17.

At this time, as explained in the section of the prior art, the pressing pieces 19 and 20 as shown in FIG. 1(2) are used to press and connect. The pressing piece 19 presses the vicinity of the central position of the head substrate 12, avoiding the comparatively peripheral portion of the throat substrate 12 where the heating resistor array 13 and the drive circuit 14 are formed. The pressing piece 20 presses a portion of the heat sink 16 that corresponds to the pressing position of the pressing piece 19 . In this way, the thickness of the adhesive layer 17 (for example, 20 μm or less) can be made uniform over the entire length of the head substrate 12 and the heat sink 16.

The reason why the thickness t2 of the heat sink 16 is selected to be 2.0 mm or less as described above is as follows. The amount of curvature d3 of the heat sink 16 is determined by the thickness t2 of the heat sink 16 being, for example, 1.0.
Comparing the cases of mm and 2.0 mm, the pressing piece 1
9.20 is 800 g, it is confirmed that the pressure decreases from 85 μm to about 10 μm (:). Also, when the head substrate 12 is loaded with 800 g by the pressing piece 19.20, the head substrate 12 curves by 50 μm as the amount of curvature d2. Therefore, when the thickness of the heat sink 16 is large, the head substrate 12 is bonded to the curved shape of the heat sink 16, which makes it difficult for printing quality to deteriorate due to heat radiation. , printing unbalance due to the curvature of the heat sink is likely to occur.

The head substrate 12 normally has a curvature d2 with a length L2 of 30μ.
In the case of m, it is about 15 μm. Therefore, at the stage when the head substrate 12 and the heat sink 16 are manufactured separately, the amount of curvature d2 of the head substrate 12 does not become larger than the amount of curvature d3 of the heat sink 16, and the head substrate 12 is curved in the same shape as the heat sink 16. Thereby, the thickness of the adhesive layer 17 can be made uniform along the longitudinal direction.

On the other hand, at the manufacturing stage as shown in FIG. 5(1), the head substrate 12 has a flat plate shape, and the heat sink 16 is
1) In the case of a curved shape similar to that shown in the figure, when these are pressed and bonded as described above, the pressing pieces 19 and 20 will be
This has the effect of bringing these center positions closer to each other, so that the heat sink 16 is closer to the head substrate 1 as shown in FIG. 5(2).
2 and become mutually flat.

Further, as shown in No. 6 [1a(1)], when the heat sink 16 is formed to be curved as described above, and on the other hand, the head substrate 12 is curved in the opposite direction to the heat sink 6, The pressing pieces 19, 20 have the effect of bringing their center positions closer to each other, so that they become mutually flat as shown in FIG. 6(2).

Using the heat dissipation plate 16 and head substrate 12 having the dimensions described above, the amount of curvature d2 when pressurizing the vicinity of their respective center positions with the press piece 1920 Figure 7 shows the change in d3. The amount of curvature d2 of the head substrate 12 is shown in FIG.
The amount of curvature d3 of No. 6 is shown in FIG. Such an amount of curvature is determined when the Young's modulus of the head substrate 12 is 40〉 and 10'g.
/mm', and the Young's modulus of the heat sink 16 is 7.17>:
]O'g/mm 2, it is calculated using the following equations 1 and 2.

ω: Pressure force r, plate length E: Young's modulus I; second moment of area bh' ■-□ ... (2) b7 plate width h: If you follow this example by making it more than the plate thickness, the heat sink 16 first
As shown in FIG. 1, by forming the curved shape in advance, when bonding with the head substrate 12 under pressure,
The layer thickness of the adhesive layer 17 between these can be made uniform over its entire length, and the printing quality can be significantly improved.

[Effects of the Invention] According to the present invention as described above, when the surface of the substrate on which the heating resistor array is formed facing the heat radiating member is curved convexly in the same direction as the fixed surface of the heat radiating member, The heat dissipating member and the substrate are pressed against each other near their central positions, and are fixed to each other by an adhesive layer having the same thickness over the entire length thereof. In addition, if the substrate is flat or curved in the opposite direction to the curved direction of the heat dissipation member, the substrate and the heat dissipation member are deformed into a flat plate shape by pressing and bonding the two pieces to each other. Again, they are fixed via an adhesive layer having a uniform thickness over their entire length.

Therefore, it is possible to prevent local variations in heat conductivity between the substrate and the heat dissipation plate, and to prevent the heat generated by the heating resistor from being accumulated undesirably and causing undesired thermal printing. It is possible to improve the quality of thermal printing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view explaining the present invention in detail, FIG. 2 is a perspective view of a thermal head 1 according to an embodiment of the present invention, and FIG. 3 is a sectional view taken from the section line T in FIG. 2. , FIG. 4 is a process diagram explaining the manufacturing process of thermal head [1], FIGS. 5 and 6 are sectional views explaining the present invention in detail, and FIG. 7 is a diagram showing the amount of curvature of the head substrate 12 and the heat sink 16. 8 is a cross-sectional view illustrating the manufacturing process of a typical conventional thermal head 1, and FIG. 9 is a graph illustrating a conventional heat sink 7.
It is a sectional view showing one example of the curve of. 11. Thermal head, 12. Head board, 13.
Heat generating resistor array, 14. Drive circuit, 16. Heat sink, 17-
・Adhesive layer, 18...Supporting surface, t1 plate thickness, d2. d3・
...Curvature Agent Patent Attorney Number of Strokes Kei Part 1 Figure 2m Figure 4 Figure 4 Mouth E Shout ql Hito.

Claims (1)

[Scope of Claims] A thermal head in which a heat dissipating member is attached to a substrate having an array of heating resistors, the heat dissipating member having a concave curved shape or a flat plate shape on the side to which the substrate is fixed. A thermal head made of integrated adhesive.