JPH0433868A - Manufacture of thermal head - Google Patents

Abstract

PURPOSE:To prevent printing quality from being injured by heating by a method wherein the title manufacture of a thermal head is composed of a radiation plate heating process in which a radiation plate is thermally expanded at a high temperature, a ceramic substrate binding process in which a ceramic substrate is fixed by bonding to its upper surface, and a cool bending process in which this radiation plate is contracted by cooling to be bent projectingly. CONSTITUTION:A rectangular flat board like aluminium radiation plate 1 is heated in a thermostatic chamber kept at approx. 60 deg.C for a specific time. The heated radiation plate 1 is extended by thermal expansion (B). Further, a rectangular narrow width ceramic substrate 2 is placed on an upper surface of the thermally expanded plate 1, and the plate 1 is bonded to be fixed to the ceramic substrate 2 via an adhesive (C). Then, a united body of the ceramic substrate 2 bonded to the plate 1 is cooled. The plate 1 which was expanded by thermal expansion is contracted by cooling, and is projectingly bent by being pulled with the ceramic substrate 2 which is not thermally deformed. That is, the united body (the heat slinger 1 containing the ceramic substrate 2) is projectingly bent by being warped (D). Thereafter, a flexible substrate 3 connected to a pattern electrode of the ceramic substrate 2 is placed on this curved plate 1 and is fixed by pressure contact with a presser cover 4 from above.

Description

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

(b) As shown in FIG. 2, the conventional thermal head has a narrow rectangular ceramic substrate 2 on the upper surface of a rectangular flat heat dissipation plate 1, and a flexible plate connected to the back electrode of the ceramic substrate 1. The substrate 3 is placed on an auxiliary substrate 5 and arranged, and the ceramic substrate 2 and the flexible substrate 3 are pressed and fixed to the heat sink 1 from above with a presser cover 4.

The flexible substrate 3 is electrically connected to an external control circuit via a connector, and when power is supplied to a selected heating resistor in the row of heating resistors on the ceramic substrate 2, the heating resistor is activated. It generates heat and prints and records information on the recording paper that is being transported.

(c) Problems to be Solved by the Invention The thermal head prints information on recording paper fed between the heating element and the platen roller facing the heating element by generating heat. The entire thermal head generates heat due to frequent use or long-term use. Incidentally, among the thermal head constituent members, the aluminum heat sink has the highest coefficient of thermal expansion, while the ceramic substrate has almost no thermal expansion. Conventionally, a ceramic substrate is adhesively fixed to the upper surface of a heat sink at room temperature. Therefore, under normal conditions (normal temperature), the seven-laminated board and the heat sink are integrated in a flat horizontal state. Therefore, when the entire thermal head generates heat, as shown in Figure 3,
As the heat dissipation plate 1 thermally expands and stretches and is pulled toward the ceramic substrate 2, which is not thermally deformed, the entire thermal head is curved and warped in a concave shape toward the ceramic substrate (the platen roller disposed oppositely above). As a result, a gap is formed between the platen roller and the row of heating resistor elements, resulting in disadvantages such as poor printing quality.

It is an object of the present invention to provide a method for manufacturing a thermal head that solves the above problems and does not impair print quality due to heat generation.

(d) Means and operation for solving the problems The method for manufacturing a thermal head of the present invention includes a heat sink heating step of thermally expanding a heat sink at a high temperature, and bonding a ceramic substrate to the top surface of the thermally expanded heat sink. It is characterized by consisting of a ceramic substrate bonding step for fixing the ceramic substrate, and a cooling and bending step for cooling and shrinking the heat sink to which the ceramic substrate is bonded and fixed, and bending it into a convex shape.

In this thermal head, instead of adhesively fixing the heat sink and the ceramic substrate at room temperature as in the past, the heat sink is expanded by thermal expansion, and while this expanded state is maintained, the ceramic substrate is attached to the heat sink. Glue and fix the board. Thereafter, the heat sink to which the ceramic substrate is bonded and fixed is cooled (returned to room temperature).

As a result, the heat sink, which had been thermally expanded, contracts from its expanded state. In this state, it is a single piece of ceramic.

Since the substrate hardly deforms due to heat, the heat sink that shrinks due to heat is pulled by the integrated ceramic substrate, causing the whole to warp into a convex shape (
curved). Therefore, for example, a flexible substrate to be connected to the pattern electrode of the ceramic substrate is placed on this convex heat sink (a heat sink including a ceramic substrate), and the ceramic substrate and the flexible substrate are connected to the heat sink using a presser cover from above. By press-fixing the thermal head to the thermal head, it is possible to obtain a thermal head that is entirely convex at room temperature.

In this way, the entire thermal head is placed above (it is placed opposite to the row of heat generating resistor elements on the ceramic substrate).
This results in a convex warp with respect to the platen roller, and no gap is created between the platen roller and the heat generating resistor element array. Further, when the entire thermal head generates heat due to frequency of use or long-time use, the thermally expanding heat sink changes from its normal convex shape to a flat (horizontal) state. Therefore, even if the entire thermal head generates heat during use, high print quality can be achieved.

(e) Examples FIG. 2 is a perspective view showing the thermal head.

The thermal head includes a narrow rectangular ceramic substrate 2 and a flexible substrate 3 connected to the pattern electrodes of the ceramic substrate 2 on the upper surface of a rectangular flat heat dissipation plate 1 and an auxiliary substrate 5.
The ceramic substrate 2 and the flexible substrate 3 are pressed and fixed to the heat sink 1 from above by a presser cover 4.

FIGS. 1(A) to 1(D) are process step diagrams showing the manufacturing process of the main parts of the embodiment thermal head.

As the heat dissipation plate 1, a rectangular flat plate having a constant width, length, and thickness is used as in the conventional case [FIG. 1(A)]. This rectangular flat aluminum heat sink 1 is heated for a certain period of time in a constant temperature room maintained at about 60°C. The heat sink l has the largest coefficient of thermal expansion among the constituent members of the thermal head. Therefore, the heated heat sink 1 thermally expands and expands [FIG. 1(B)].

Furthermore, a narrow rectangular ceramic substrate 2 is placed on the top surface of the thermally expanded heat sink 1, and the heat sink 1 and the ceramic substrate 2 are bonded and fixed with an adhesive (Fig. 1). (
C)]. Then, the integrated body in which the ceramic substrate 2 and the heat sink 1 are bonded is cooled. In other words, this one piece is taken out of the thermostatic chamber at room temperature. The ceramic substrate 2 hardly undergoes thermal deformation. Therefore, the heat dissipating plate 1 that has expanded due to thermal expansion is cooled and shrinks, thereby preventing the ceramic from being thermally deformed.

It is pulled by the substrate 2 and curved into a convex shape. In other words, the integrated body (the heat sink 1 including the ceramic substrate 2) warps into a convex shape [FIG. 1(D)]. After that, as shown in FIG. 2, for example, a flexible substrate 3 to be connected to the pattern electrodes of the ceramic substrate 2 is placed on the convex heat sink (heat sink including the ceramic substrate 2) 1, and the flexible substrate 3 is placed from above. Ceramic substrate 2 and flexible substrate 3 are held together with presser cover 4.
and are pressed and fixed to the heat sink 1.

As a result, under normal conditions (at room temperature), the entire thermal head warps in a convex manner with respect to the platen roller, which is disposed above (disposed opposite to the row of heating resistor elements on the ceramic substrate). There is no gap between the heating resistor element row and the heating resistor element array. Further, when the entire thermal head generates heat due to frequency of use or long-time use, the thermally expanding heat sink 1 changes from its normal convex shape to a flat (horizontal) state. Therefore, to thermal in use, 7
High print quality can be achieved even when the entire board generates heat.

(F) Effects of the Invention In this invention, as described above, the heat sink is thermally expanded, a ceramic substrate is adhesively fixed to the upper surface of the expanded heat sink, and then the heat sink integrated with the ceramic substrate is cooled and shrunk. By doing this, we decided to obtain a thermal head that is curved in a convex shape as a whole. As a result, the shape is warped,
No gap is created between the platen roller and the heat generating resistor element array. Further, when the entire thermal head generates heat due to frequency of use or long-term use, the thermally expanding heat sink changes from its normal convex shape to a flat (horizontal) state. Therefore, it has excellent effects that achieve the purpose of the invention, such as achieving high printing quality even when the entire card generates heat during use.

[Brief explanation of drawings]

1(A) to 1(D) are step diagrams showing the manufacturing process of the thermal head according to the embodiment. FIG. 1(A) is a diagram showing the heat sink at room temperature, and FIG. (B) is a diagram of a heat sink that has been thermally expanded, Figure 1 (C) is a diagram of a ceramic board that has been bonded and fixed to a thermally expanded heat sink, and Figure 1 (D) is a diagram of a ceramic board that has been bonded and fixed to a heat sink that has been thermally expanded. Figure 2 is a perspective view showing the thermal head, and Figure 3 is a diagram showing the heat sink including the substrate curved into a convex shape. It is an explanatory view showing a defect. 1: Heat sink, 2: Ceramic board. Patent applicant ROHM Co., Ltd. agent
Patent Attorney Shigeru Nakamura Figure 2 Figure 3

Claims (1)

[Claims] (1) A heat sink heating step in which the heat sink is thermally expanded at high temperature;
A ceramic substrate adhesion step in which a ceramic substrate is bonded and fixed to the upper surface of the thermally expanded heat sink, and a cooling curving step in which the heat sink to which the ceramic substrate is bonded and fixed is cooled to shrink and curved into a convex shape at room temperature. A method for manufacturing a thermal head comprising: