JP2766406B2 - Setting method of warpage dimension in line type thermal print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a line-type thermal printhead which is used in a facsimile or a printer, etc., in which a curved warp is imparted to the line-type thermal printhead in advance along its longitudinal direction. The present invention relates to a method for setting a warpage dimension to an arbitrary value.

[0002]

2. Description of the Related Art In general, a line type thermal print head of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-292005 or Japanese Patent Application Laid-Open No. 2-2920056, and as shown in FIGS. The head substrate 1 made of ceramic having the heating resistor 2 formed in a straight line on the upper surface is bonded to the surface of a heat radiating plate 3 made of metal such as aluminum with an adhesive. In FIG. 4, reference numeral 4 denotes a driving IC, reference numeral 5 denotes a flexible circuit board, reference numeral 6 denotes a cover, and reference numeral 7 denotes a platen.

In this type of line type thermal print head, when the heating resistor generates heat, the thermal expansion difference between the ceramic head substrate 1 and the metal radiator plate 3 causes the thermal print difference. Both ends in the longitudinal direction of the head approach the platen 7 and the central portion in the longitudinal direction of the thermal print head is separated from the platen 7, that is, the thermal print head has a tendency to bend into a concave curved shape with respect to the platen 7. .

Therefore, in addition to this, when the thermal print head is mounted on a facsimile or the like, the line type thermal print head is taken into consideration in consideration of the pressing force on the thermal print head and the rigidity of the thermal print head. In advance, as shown in FIG. 5, both ends of the thermal print head in the longitudinal direction are separated from the platen 7 and a central portion in the longitudinal direction of the thermal print head approaches the platen 7, that is, with respect to the platen 7. Then, a warp having a convex curved shape is given to the facsimile or the like in a state where the convex curved warp is given.

Conventionally, as described above, in order to previously impart a convex curved warp to a thermal print head, a metal heat radiating plate 3 is attached to the head substrate 1 with respect to the heat radiating plate 3. Before bonding, a predetermined warp dimension e is set by forcibly plastically deforming the platen 7 into a convex curved shape.

[0006]

However, in the case where the thermal print head is previously provided with a convex curved warp, the warp dimension e is the length dimension of the thermal print head and the warp dimension e. An appropriate value exists depending on the type of the facsimile or the like. In other words, the warpage dimension e when the initial application is performed is the length dimension of the thermal print head and the type of the facsimile or the like using the thermal print head. It changes according to.

Therefore, according to the conventional method of forcibly plastically deforming the heat radiating plate, the heat radiating plate having a different curvature factor when plastically deforming into a convex curved shape has a different length dimension and model. It is necessary to manufacture many types according to the change, and it requires a great deal of trouble and strict dimensional control in its manufacture. There was a problem that the cost required for the storage increased significantly.

According to the present invention, there is provided a thermal print head in which a ceramic head substrate is bonded to a metal radiator plate with an adhesive by bonding the head substrate to the radiator plate with an adhesive. The warp is deformed in a convex curved shape with respect to the platen, and the degree of the warp is proportional to the length of the adhesive applied along the longitudinal direction of the thermal print head. It is an object of the present invention to pay attention to a certain point and to solve the above-mentioned problem by using this fact.

[0009]

That is, the present invention provides:
"The ceramic head substrate with the heating resistor formed in a straight line on the upper surface is partially placed at the approximate center of the surface of a heat sink made of metal such as aluminum along the longitudinal direction. In a line-type thermal print head that is adhered through an applied adhesive, an application length dimension of the adhesive along the longitudinal direction of the thermal print head is adjusted by an adhesive applied to a substantially central portion of the thermal print head. The thermal print head is dimensioned so as to be curved and deformed convexly to the platen along the longitudinal direction.
The warpage dimension is set by increasing or decreasing the application length dimension of the adhesive. Is the thing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In this figure, reference numeral 1 denotes a head substrate formed of ceramic and having a length L, on the upper surface of which a heating resistor 2 is formed so as to extend in a straight line.

Reference numeral 3 denotes an aluminum radiator plate, and the head substrate 1 is partially applied to the upper surface of the radiator plate 3 over a length S substantially at the center thereof along the longitudinal direction. It adheres via the heat-curable adhesive A.
When bonding with the heat-curable adhesive A, the heat-curable adhesive A is applied to one or both of the head substrate 1 and the heat radiating plate 3, and both are bonded at room temperature. By heating to the appropriate temperature,
The heat-curable adhesive A is cured, and between the coefficient of thermal expansion of the ceramic head substrate 1 and the coefficient of thermal expansion of the aluminum radiator plate 3, the aluminum radiator plate 3 is hardened.
Since there is a thermal expansion difference that the coefficient of thermal expansion is larger in the above, when the thermosetting adhesive A is cured by heating to an appropriate temperature as described above and then cooled to room temperature, the thermal print head is FIG.
As shown by a two-dot chain line, it will bend in a curved shape along its longitudinal direction, and the warp deformation is
Becomes convex with respect to the platen.

In this case, the present inventor conducted an experiment on the influence of the application length dimension S of the heat-curable adhesive A on the warpage deformation of a thermal print head having a length L of 230 mm. It has been found that the warpage dimension e at the time of warping deformation as described above is substantially proportional to the application length dimension S of the heat-curable adhesive A as shown by the curve in FIG.

Accordingly, as shown by a two-dot chain line in FIG. 2, the thermal print head is warped in a convex curved shape with respect to the platen by bonding using the heat-curable adhesive A. The dimension e increases when the application length dimension S of the thermosetting adhesive A is increased, and decreases when the application length dimension S of the thermosetting adhesive A is shortened. By applying the coating length dimension S, the thermal print head can be deformed in a convexly curved shape with respect to the platen along the longitudinal direction, and the thermal printing head can be deformed by increasing or decreasing the coating length dimension S. Can be set arbitrarily when warping is deformed.

According to an experiment conducted by the present inventor, FIG. 6 shows the case where a room temperature curing type adhesive is used as an adhesive for bonding the ceramic head substrate 1 to the aluminum heat sink 3. As described above, since the same tendency is exhibited as when the heat-curable adhesive is used, the present invention is not limited to the case where the heat-curable adhesive is used as the adhesive, and the room temperature-curable adhesive is used. This is applicable even when an adhesive is used.

[0015]

As described above, according to the present invention, it is possible to provide a thermal print head with a convexly curved warp with respect to a platen in advance by moving the head substrate of the thermal print head to the heat sink. The adhesive can be achieved by using an adhesive, and the warpage dimension can be arbitrarily set by increasing or decreasing the application length dimension of the adhesive. Therefore, it is not necessary to perform plastic deformation in a curved shape so as to have the following effect. Therefore, there is an effect that the cost required to impart a predetermined convex warp to the platen to the thermal print head can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a thermal print head according to an embodiment of the present invention is disassembled.

FIG. 2 is a perspective view of a thermal print head according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating a relationship between an adhesive length dimension and a warpage dimension of a heat-curable adhesive.

FIG. 4 is a vertical sectional front view showing a state in which the thermal print head is mounted on a platen.

FIG. 5 is a right side view of FIG.

FIG. 6 is a view showing the relationship between the bonding length dimension and the warpage dimension of the cold-setting adhesive.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head board 2 Heating resistor 3 Heat sink A Adhesive

Claims (1)

(57) [Claims] 1. A ceramic head substrate having a heating resistor formed in a straight line on an upper surface thereof is disposed at a substantially central portion along a longitudinal direction of the surface of a metal heat radiating plate made of aluminum or the like. In a line type thermal print head which is adhered through an adhesive partially applied to the adhesive, the longitudinal direction of the thermal print head in the adhesive
The application length dimension along
The thermal print head with the adhesive
Along the platen to bend convexly to the platen
A method of setting a warpage dimension in a line type thermal print head , wherein the warp dimension is set by increasing or decreasing the length of application of the adhesive .