JPH0573588B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a thermal head provided with a driving IC for driving a heating element.

(b) Prior art and its drawbacks A thermal head equipped with a driving IC for driving a heating element is molded with resin or the like to protect the IC. However, if the resin mold is used as it is, its mechanical strength is low, and there is a risk that the IC or the wiring around it, such as wire bond, may be destroyed by receiving external force or touching the platen or paper. Conventionally, therefore, the surface of the IC is protected by covering it with a stainless steel plate, etc., as shown in FIGS. 4A and 4B. 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 its back surface is bonded to the heat sink 1. 3 is a cover that covers 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 must be at least a certain distance. It is necessary to design for a long time. 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 accuracy of applying the resin 6 that molds the drive IC 4 is not very good, it is necessary to leave some space between the molded part and the cover 3. However, it was not possible to reduce the thickness of the cover 3 relative to the substrate 2 very much due to the influence of variations in the dimensional accuracy of the cover 3 and the like.

(c) Purpose of the invention The purpose of this invention is to miniaturize the entire thermal head, and to provide a thermal head that increases the gap between the platen and the protection part of the drive IC, allowing flexibility in the way print paper is passed through the head. The aim is to provide a head.

(d) Structure and Effects of the Invention The present invention provides a heating element formed on the surface near the tip and a driving IC for driving the heating element.
In a thermal head consisting of a board mounted near the base thereof, and a heat sink that holds the board in contact with the back side of the board, with the board attached to the heat sink, the drive IC is mounted near the drive IC. In addition, the device is characterized in that protrusions that protrude parallel to both sides of the substrate and are higher than the height of the driving IC are integrally molded.

According to this invention, when the board is attached to the heat sink, the heating element driving IC mounted on the board is located lower than the protrusion height of the protrusion integrally formed on the heat sink. The paper does not come into direct contact with the drive IC, and the drive IC is reliably protected from these external forces. Furthermore, since the protrusions are integrally formed with the heat sink, when manufacturing the thermal head of the present invention, there is no need for a special manufacturing process for providing the protrusions on the heat sink. A protrusion that protrudes higher than the height of the driving IC can be easily provided.
Therefore, the conventional stainless steel cover is not required, the number of parts is reduced, assembly is easy, and an inexpensive thermal head can be obtained. Also,
Since the protrusions are provided in parallel along both sides of the substrate, the substrate is placed between the two parallel protrusions, and the protrusions also act as alignment members for the substrate with respect to the heat sink.

(e) Embodiment FIG. 1 is a diagram showing the structure of a thermal head which is an embodiment of the present invention. In 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 an IC 4 for driving the heating element 8 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 the horizontal movement of the thermal head. 1 is 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 IC 4. Since the height of this protrusion exceeds the height of the mold 6 of the IC 4, even if printing paper etc. comes into contact with this part, the print paper will only contact the protrusion 1a, and the IC mold 6 and its surroundings will 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 part 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. In this way, the protrusion 1a
are provided on both sides of the drive IC 4, so
Although the upper part of the mold is open, there is no risk of local contact with the platen of the thermal printer.

As shown in FIG. 1C, the platen 5 and the protrusion 1a
Since there is a sufficient distance between the platen 5 and the projection 1a, printing paper such as thermal paper or thermal transfer paper can be smoothly passed between the platen 5 and the protrusion 1a. In addition, the protrusion is rounded overall and has a shape that is gently inclined in the longitudinal direction, so that 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. Never. Note that 1b shown in FIG. 1A 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.

Figure 2 is a diagram showing only the heat sink 1;
is a plan view, B is a front view, and C is a side view. This heat sink is made of aluminum die-cast, 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 allowable range of the height of the IC mold part, which improves the protection of the IC. The thickness at the part can be made thinner. Furthermore, even when designing under strict conditions such as having a small gap between the platen and the protection part of the IC,
Since the gap between the protective portion of the thermal head and the platen can be accurately maintained, defects due to variations in dimensional accuracy are less likely to occur, and the yield rate of thermal heads can be improved. Moreover, since the IC can be protected with just the heat sink without using a stainless steel cover, the number of parts and costs can be reduced.

In the above embodiment, the protrusion 1a is attached to the substrate 2.
Since it is provided so as to be in contact with both sides of the substrate 2, it can also be used as a positioning protrusion when bonding the substrate 2 to the heat sink 1.

[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 shows a plan view, B shows a front view, and C shows a side view. Figure 2 is a diagram showing the structure of the heat sink of the thermal head.
In the figure, A shows a plan view, B shows a front view, and C shows a side view. FIG. 3 is a diagram showing the structure of the IC protection part of the same thermal head, and FIGS. 4A and 4B are diagrams showing the structure of a conventional thermal head. 1... Heat sink, 2... Board, 4... IC, 6...
...Mold, 1a...Protrusion.

Claims (1)

[Scope of Claims] 1. A substrate on which a heating element is formed on the surface near the tip and a driving IC for driving the heating element is mounted near the base, and the substrate is held in contact with the back surface of the substrate. In a thermal head comprising a heat dissipation plate, the heat dissipation plate has a protrusion higher than the height of the drive IC in the vicinity of the drive IC and parallel to both sides of the board when the board is attached. A thermal head characterized by integrally molded protrusions.