JPS6221558A - Thermal head - Google Patents

Abstract

PURPOSE:To protect a drive IC from the external forces such as a platen and a sheet, by providing projections on a radiation board so as to be corresponding to the sides of the drive IC. CONSTITUTION:Projections 1a are formed on a radiation board 1 corresponding to the sides of an IC 4. When brought into contact with the printing sheet, the projections higher than molds 6 in the IC 4 allow a printing sheet to abut the projections 1a but the molds 6 and thereabouts in the IC. Therefore, with the thermal printer incorporating the thermal head, the drive IC for the thermal head and thereabouts can be protected by the projections 1a.

Description

Detailed Description of the Invention: ta+ Technical Field This invention relates to a thermal head provided with a driving IC for driving a heating element.

(bl Conventional technology and its drawbacks Thermal heads equipped with a driving rC that drives the heating element are molded with resin etc. to protect the IC. However, the mechanical strength of the resin mold is low and it is not susceptible to external force. There is a risk that the IC or the wiring around it, such as wire bonds, may be destroyed by touching the platen or paper.
As shown in (B), the surface of the IC is protected by covering it with a stainless steel plate or the like. In the figure, reference numeral 2 denotes a substrate on which a heating element 8 is formed and a driving IC 4 for driving the heating element is provided, and the back surface of the substrate 2 is bonded to the heat dissipation plate 1. Reference numeral 3 denotes a cover that covers the periphery of the driving IC 4. As shown in FIG. 5B, it is necessary to set the positional relationship between the platen and the thermal head so that the heating element of the thermal head contacts the platen 5 in parallel. However, in such a case, the thickness from the surface of the substrate 2 to the top surface of the cover 3 is large, and in order to prevent the cover from coming into contact with the platen, the distance from the part covered by the cover 3 to the heating element 5 is designed to be longer than a certain degree. There is a need to. Furthermore, since the gap between the platen 5 and the cover 3 cannot be made very wide, the way the printing paper can be passed through is limited. This problem can be solved by keeping the thickness of the cover 3 low, but since the coating precision of the resin 6 that molds the drive IC 4 is not very good, it is necessary to provide some space between the molded part and the cover 3. Also, due to variations in the dimensional accuracy of the cover 3, the board 2
However, it was not possible to reduce the thickness of the cover 3 very much.

(0) Purpose of the Invention The purpose of this invention is to miniaturize the entire thermal head, and to increase the gap between the platen and the protection part of the drive IC, so that printing paper can be passed through the thermal head more freely. The purpose is to provide the head.

+d) Structure and Effects of the Invention To summarize, the present invention provides a heating element and a driving IC for driving the heating element on the surface of a substrate, a heat sink is attached to the back surface of the substrate, and the drive IC for driving the heat sink is attached to the back surface of the substrate. IC for
It is characterized in that a protrusion is formed at a portion corresponding to the side portion of the holder.

According to this invention, the drive IC provided on the substrate can be reliably protected from external forces by the protrusion provided on the heat dissipation plate without allowing the platen or paper to come into direct contact with it, and also eliminates the need for a stainless steel cover. It can be constructed at low cost.

(e) Embodiment FIG. 1 is a diagram showing the structure of a thermal conductor according to an embodiment of the present invention. The figure (A') shows a plan view, (B) shows a front view, and (C) shows a side view. Reference numeral 2 denotes a substrate made of ceramic, on the surface of which a heating element 8 and a driving IC 4 are provided, and a cable 7 for inputting and outputting signals with the outside is connected. This cable is a flexible cable and does not interfere with horizontal movement of the thermal head.

Reference numeral 1 denotes a heat sink, and the back surface of the substrate 2 is bonded to the heat sink 1 with an adhesive having high thermal conductivity. As is clear from the figure, protrusions 1a are formed on the heat sink corresponding to both sides of the IC4. Since the height of this protrusion exceeds the height of the mold 6 of the IC 4, even if printing paper or the like comes into contact with this part, the print paper will only contact the protrusion 1a, and the IC mold 6 and its surroundings will be removed. Do not come into contact with. Therefore, when this thermal head is incorporated into a thermal printer, the driving IC of the thermal head and its surroundings can be protected by the projection 1a.

FIG. 3 is a partial side view showing the protection section of the IC. As is clear from the figure, the protrusion 1a exceeds the height of the mold 6 covering the IC 4 and extends over the entire side of the IC. Since the projections 1a are thus provided on both sides of the driving IC 4, although the upper part of the mold is in an open state, there is no possibility that the platen of the thermal printer will come into contact with it locally.

As shown in FIG. 1(C), there is a sufficient distance between the platen 5 and the protrusion 1a, so that printing paper such as thermal paper or thermal transfer paper can be passed smoothly between the platen 5 and the protrusion 1a. Can be done.

In addition, the protrusions are rounded overall and in the longitudinal direction.

It has a gently sloping shape, and when paper is installed between the platen and the thermal head, even if the paper comes into contact with the protrusion 1a, it will not get caught. Note that 1b shown in FIG. 1(A) is an escape groove when the back surface of the substrate 2 and the heat sink 1 are bonded together with an adhesive, and excess adhesive collects in this groove and hardens.

FIG. 2 is a diagram showing only the heat sink 1, in which (A) is a plan view, (B) is a front view, and (C) is a side view. This heat sink is made of die-cast aluminum, and its surface is coated with black paint or anodized. In this way, since the protrusion 1a is integrally formed with the heat sink itself, sufficient dimensional accuracy can be obtained. Therefore, even if the dimensional accuracy of the height of the IC mold part is poor, the height of the protrusion can be accurately designed taking into account the tolerance range of the height of the IC mold part. The thickness can be reduced. For example, even when designing under strict conditions such as having a small gap between the platen and the IC protection part, the gap between the IC protection part and the platen can be maintained accurately, reducing variations in dimensional accuracy. This reduces the occurrence of defects caused by the thermal head, and improves the rate of non-defective products as a thermal head. Moreover, since the IC can be protected with only the heat sink without using a stainless steel cover, the number of parts and costs can be reduced.

In the above embodiment, since the projections 1a are provided in contact with both sides of the substrate 2, the substrate 2 is connected to the heat sink 1.
It can also be used as a positioning protrusion when bonding to.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the structure of a thermal head according to an embodiment of the present invention, in which (A) is a plan view, (B) is a front view, and (C) is a side view. FIG. 2 is a diagram showing the structure of the heat sink of the thermal head, in which (A) is a plan view, (B) is a front view, and (C) is a side view. FIG. 3 is a diagram showing the structure of the IC protection part of the same thermal head, and FIGS. 4(A) and (B) are diagrams showing the structure of the conventional thermal head. 1-heat sink, 2-substrate, 4-IC1 6-mold, 1a-protrusion.

Claims (1)

[Claims] (1) A substrate having a heating element formed on its surface and provided with a driving IC for driving the heating element, and a heat sink attached to the back side of the substrate, wherein the driving IC of the heat sink is attached to the back surface of the substrate. A thermal head characterized in that a protrusion is formed on a portion corresponding to a side portion of the thermal head.