JPS6019552A - Thermal print head - Google Patents

Abstract

PURPOSE:To uniformize the contact between a heat generating body and a thermosensitive paper by providing a heat generating body on an insulating substrate while a projection is formed on the substrate corresponding to the heat generating body having a heat storage effect for storing heat generated from the heat generating body. CONSTITUTION:An insulating substrate 2 made of ceramic or the like is arranged for a thermal print heat 1 while a projection 4 with a circular arc section is formed on one surface 2a of the substrate 2 almost at the center thereof. In addition, a heat generating body 8 is provided on a heat storage layer 6 positioned above the projection 4. A heat generating body 8 is connected to a conductor layer 10 for electrically energizing it 8 while provided with a protective layer 12. Therefore, when the thermal print head 1 applies, the even thickness of the projection 4 enables the invariably stable contact of the heat generating body 8 with a thermosensitive paper 14. This also enables heat generated from the heat generating body 8 to be stored in required quantities with the projection 4 as well as the heat storage layer 6.

Description

[Detailed description of the invention] The present invention relates to thermal printheads.

In a conventional thermal print head, a flat insulating base is provided, a heat storage layer is provided on the surface of the base, and a heating element is formed on the heat storage layer, so that the heat generated by the heating element is conducted to the base. There is a type of thermal paper that uses a heat storage layer to prevent the heat from being transmitted and lost, and effectively transmits the generated heat to the thermal paper. However, in this structure, since the thickness σ of the heating element is small, contact with the thermal paper is insufficient, which tends to cause uneven printing. For this purpose, as shown in FIG. 1, a glaze layer is provided on a part of the surface of the base a, and a heating element d is formed on this craze layer 1) via a heat storage layer C. There is one in which the heat-sensitive paper can easily come into contact with the heating element d. e is a protective layer. However, since the glaze layer is separately formed on the substrate A'2, the surface tends to be uneven and the thickness σ tends to be non-uniform in the longitudinal direction. In other words, even if the glaze layer 1) is provided, the thermal paper may not come into uniform contact with the heating element d, and as a result, the amount of heat stored in the heat storage layer C becomes unstable, making it difficult to wear shoes 1.
The distribution deteriorates, causing uneven printing and deteriorating print quality.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to ensure uniform contact between a heating element and thermal paper and to maintain good heat distribution of the heating element to prevent uneven printing.

In order to achieve this object, the present invention forms a protrusion on an insulating base and provides a heating element on the protrusion.

Hereinafter, the present invention will be explained in detail based on the embodiments shown in the drawings.

FIG. 2 is a sectional view of the thermal print head of this embodiment. This thermal printing head 1 includes an insulating base body 2 made of ceramic or the like. A protrusion 4 having an arcuate cross section is formed on one surface 22 of the base 2 at approximately the center thereof. This protrusion 4 is integrally formed at the same time as the base body 2 is fired. Therefore, since the shape is determined by the precision of the mold during molding, the surface has few irregularities and the thickness is uniform. In addition, the shape of the protrusion 4 has a high σl] of 5 to 5 due to the heat accumulation described later.
It is preferable that the arc length t is about 500 μm and the arc length t is about 0.5 to 5 mm.

” - On the surface 2a of the base 2, a heat storage layer 6 is provided covering the protrusion 4.
is formed, and a heating element 8 is provided on the heat storage layer 6 located roughly on one side of the projection 4.

The heating element 8 is electrically connected to a 4' base layer 10 for supplying electricity to the heating element 8. /, [O, 12 is a protective layer.

Therefore, when applying this thermal print head 1, the protrusions ml
Since the thickness of i 4 is uniform, the heating element 8 stably contacts the thermal paper 14 during long periods. Moreover, the necessary amount of heat generated by the heating element 8 is stored in the heat storage layer 6 as well as in the protrusion 4 . Therefore, good heat distribution is maintained.

In order to confirm the printing effect of the thermal print head 1 of this embodiment, the shape of the protrusion 4 is set to have a height g(h)2o oμ and an arc length σ(
A thermal print head of April Q mm was formed and compared with a conventional thermal print head. As a conventional product, a product with a craze layer formed thereon was used instead of 11'X f;134. As a result, it was confirmed that clear fonts with no uneven printing could be obtained compared to conventional products, and that the power consumption required for heating could be reduced by about 15% due to the heat storage effect of the projections 4.

In the above embodiment, the heat storage layer 6 is provided between the base body 2 and the heating element 8, but if the amount of heat storage is adjusted by appropriately setting the shape and size of the protrusions ali 4, the heat storage layer 6 can be It can also be omitted. Further, the shape of the protrusion 4 is preferably arcuate in relation to the thermal paper 14, but it is needless to say that the shape is not limited to this.

As described above, according to the present invention, a protrusion is formed on an insulating base and a heat generating element is placed on the protrusion, so that the thermal paper comes into uniform contact with the heat generating element. Since the necessary amount of heat is accumulated in the protrusion, the heat distribution of the heating element is also good, and the excellent effect of producing a high-quality J-shaped head with no uneven printing is achieved. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a thermal printing head showing a conventional example, and FIG. 2 is a sectional view of a thermal printing head showing an implementation IZIJ of the present invention. DESCRIPTION OF SYMBOLS 1...Thermal printing head, 2...Base body, 4...Protrusion base, 8...Heating element. Applicant: ROHM Co., Ltd. Agent: Patent Attorney Oka 1) Hide Kazu

Claims (1)

[Claims] (1) In a thermal print head comprising a heating element on an insulating base, a protrusion for storing heat generated from the heat generating element is formed on the base corresponding to the heat generating element, and this protrusion t A thermal print head having a shape that provides a predetermined amount of heat storage effect.