JP2652749B2 - Thermal print head and method of manufacturing the same - 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 printing head for use in, for example, a line printer and a method for manufacturing the same.

[0002]

2. Description of the Related Art A thermal printing head of a line printer generally includes a heat radiating plate 1 as shown in FIG. 4, and a ceramic substrate 2 is adhered to a surface of the heat radiating plate 1 through a compound 10 made of silicon. 2, a heating element 3 which is long in the direction perpendicular to the paper is provided.

[0003]

SUMMARY OF THE INVENTION
Is used for promoting heat conduction from the ceramic substrate 2 to the radiator plate 1.
In the case where the heating temperature unevenness occurs due to the variation in the resistance value in each dot portion of the heating element 3, if the heat conduction to the heat radiating plate 1 via the compound 10 is too good, the heating temperature unevenness in the heating element 3 is more remarkable. And printing unevenness occurs.

Therefore, it is conceivable that the heat conduction to the radiator plate 1 is made slightly insensitive by appropriately increasing the thickness of the compound 10 as shown in FIG. However, when the compound 10 is applied thickly over the entire surface, a part of the compound 10 protrudes when the substrate 2 is bonded, which is not preferable in view of the structure of the thermal print head.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermal printing head which is excellent in printing performance without uneven heating temperature of a heating element.

[0006]

According to the present invention, in a first aspect of the present invention, a heat radiating plate made of a metal is attached to a surface of a heat radiating plate via a heat conductive compound. In the print head, the compound has a middle height, and the substrate is stuck on the middle along the compound ,
The configuration is such that the substrate is provided such that the heating element is located above the middle and high portions of the substrate.

According to a second aspect of the present invention, a thermal print head is manufactured by applying a heat conductive compound to the surface of a metal radiator plate at an intermediate height, and applying heat to the surface of the radiator plate on which the compound is applied. A substrate provided with a body was attached and provided such that the heating element was positioned above the middle and high portions of the compound.

[0008]

According to the first aspect of the present invention, the heat conduction to the heat radiating plate is somewhat insensitive due to the compound having a middle height just below the heating element, thereby suppressing the temperature unevenness of the heating element and the substrate. The heating element at that position also projects toward the printing paper, so that the heating element always makes good contact with the printing paper.

According to the second aspect of the present invention, it is possible to obtain a thermal print head in which unevenness in the temperature of the heating element is suppressed and the heating element always makes good contact with the printing paper. Since only the intermediate layer is applied, the compound does not protrude from the periphery of the substrate when the substrate is attached.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 3 shows an overall cross section of the thermal print head according to the embodiment of the present invention. This thermal print head comprises a heat radiating plate 1 made of aluminum and a ceramic substrate 2 attached to the upper surface thereof.

On the upper surface of the ceramic substrate 2, a heating element 3 composed of a belt-shaped continuous heating element is provided in a straight line, and a large number of dot portions formed on the heating element 3 are connected to an electric circuit composed of an IC or the like. The printing is performed on the thermal paper 6 which is selectively energized and heated by the heating paper 4 and pressed against the heating element 3 via the roller platen 5. Reference numeral 7 denotes an input flexible substrate, one end of which is pressed against the end of the ceramic substrate 2 to connect the printed circuit of the flexible substrate 7 to the printed circuit of the ceramic substrate 2. Reference numeral 8 denotes a press-contact cover for pressing and fixing the flexible substrate 7,
A protective cover 9 for the electric circuit 4 is connected to this.

The ceramic substrate 2 is adhered and fixed on the heat sink 1 through a compound 10 made of silicon having excellent thermal conductivity. And compound 10
As shown in FIG. 1, the upper layer, which is narrower than the lower layer, is printed and coated twice so as to form a middle height, and the ceramic substrate 2 is adhered so that the heating element 3 is located at the middle height of the compound 10. As a result, the thickness of the compound 10 immediately below the heating element 3 is set to be larger than that of the peripheral portion. By this attachment, as shown in FIG. 2, the ceramic substrate 2 has a slightly middle height, but since the thickness of the compound 10 is about several tens of microns, there is no obstacle in mounting.

As a means for applying the compound 10 in a middle height, as described above, in addition to applying twice, the outer peripheral surface of the compound applying roller is slightly hollowed and the compound 10 is applied in a middle height by one roller application. Can also.

[0014]

As described above, according to the present invention, since the heating element is located at the middle and high positions of the compound, the heat conduction to the heat radiating plate immediately below the heating element is somewhat insensitive, and the temperature of the heating element is reduced. The occurrence of unevenness is suppressed, and the substrate also has an intermediate height, so the heating element at that location also protrudes toward the printing paper, and the heating element always makes good contact with the printing paper. Can be enhanced.

[0015] In addition, since the compound is applied only in a required portion in a middle-high state during manufacture, there is an advantage that the compound does not protrude from the periphery of the substrate when the substrate is attached. To avoid the above overhang,
Conventionally, for example, a compound filling groove is provided on a heat sink, but according to the present invention, such a filling groove forming step becomes unnecessary. In the case where the filling groove is provided, a space remains in a part of the space, and the heat insulating function of the space may cause a decrease in heat radiation and a printing failure may occur. However, such a problem is also avoided.

[Brief description of the drawings]

FIG. 1 is a side view showing a ceramic substrate attaching step in an embodiment of the present invention.

FIG. 2 is a side view showing a state in which a ceramic substrate is adhered according to the embodiment of the present invention.

FIG. 3 is a vertical side view showing the entire thermal print head according to the embodiment of the present invention.

FIG. 4 is a side view of a conventional example.

FIG. 5 is a side view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat sink 2 Substrate 3 Heating element 10 Compound

Claims (2)

(57) [Claims] 1. A thermal printing head in which a substrate 2 provided with a heating element 3 is adhered to a surface of a metal heat radiating plate 1 via a thermally conductive compound 10, wherein the compound 10 has a middle height. this compound 10 above
A thermal print head in which a substrate 2 is stuck in a middle-high state along the middle, and a heating element 3 is located on a middle-high portion of the substrate 2 . 2. A heat conductive compound 10 is applied to the surface of a metal heat radiating plate 1 at an intermediate height, and the substrate 2 provided with the heating element 3 is applied to the surface of the heat radiating plate 1 where the compound 10 is applied. A method of manufacturing a thermal print head, wherein the heating element 3 is attached and provided so as to be located on a middle or high portion of the compound 10.