JPH05169697A - Thermal head - Google Patents

Abstract

PURPOSE:To realize a thermal head capable of printing with a constant density at the start of printing. CONSTITUTION:On a substrate 2, a conductor layer 9 for preheating is provided. On the conductor layer 9, a heating resistor 1 and electrodes 3, 3a are formed through an insulating layer 10. Thereafter, this is covered with a protective film 7. Electricity is conducted to the conductor layer 9 at the start of printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head used for thermal recording or thermal transfer recording, and more particularly to the structure of a heating element formed on a substrate.

[0002]

2. Description of the Related Art A conventional thermal head used in office equipment, communication equipment, etc. is composed of a plurality of heating elements, as shown in the side view of FIG. 2 (A). Substrate 2 made of alumina or the like provided with a heating portion a
And a heating element driving IC 12 is provided on the surface and the IC 1
A wiring board 4 for connecting 2 to an external circuit is fixed on a heat sink 5 made of an aluminum plate or the like. As shown in the cross-sectional view of FIG. 2B, the heat generating portion a has a glaze layer 6 formed on the substrate 2 at a portion to be the heat generating portion a long in the direction perpendicular to the plane of the drawing, and a silicon layer is formed thereon. And the like, and a large number of electrodes 3 and 3a made of aluminum or the like are formed on the heating resistor 1 and the electrodes 3 and 3a.
Is used as a power supply terminal to the heating resistor 1, and a wear-resistant protective film 7 made of, for example, tantalum oxide or silicon carbide is provided on the heating resistor 1 and the electrodes 3 and 3a to cover them. ..

However, in the thermal head of this type, at the start of printing, the glaze layer 6 below the heat generating portion a.
Since the temperature of the substrate 2 is low, the heat of the heating resistor 1 is taken by the glaze layer 6 and the substrate 2 so that the temperature of the heating resistor 1 does not rise, and the printing density of the first line at the start of printing is There was a problem of thinning.

Therefore, as a countermeasure against this, as shown in FIG. 2B, a pre-heat heat sink is provided below the heat sink 5.
There is also one provided with a data sink 8, but in this case, the heat sink 5
There is a problem that it takes time to transfer heat from the substrate 2 to the glaze layer 6 and a large amount of heat is required.

In view of the above problems, it is an object of the present invention to provide a thermal head which can efficiently raise the temperature of a heat generating portion in a short time and obtain an appropriate print density even at the start of printing.

[0006]

In order to achieve the above object, the present invention provides a thermal head having a heat sink on which a ceramic substrate for forming a heat generating portion is provided. Is formed, and the heat generating portion is formed on the conductor layer via an insulating layer.

[0007]

Since the present invention has the above-described structure, the preheating conductor layer is energized to generate heat before the start of printing, thereby reducing the degree of decrease in the temperature of the heat generating portion and ensuring a proper print density even at the start of printing. can get.

[0008]

1A is a sectional view showing an embodiment of a thermal head according to the present invention, and FIG. 1B is a sectional view taken along line H-H of FIG. In FIGS. 1A and 1B, 5 is a heat sink made of an aluminum plate or the like, 2 is the heat sink 5
It is a substrate for forming a heating element in which an insulating film is applied to the surface of a ceramic plate such as alumina or a metal plate, which is attached by adhesion or by using an appropriate fixing tool such as a screw or a rivet.

Reference numeral 9 denotes a conductor layer made of high resistance metal such as tantalum, titanium or the like for preheat provided by the present invention. The conductor layer 9 is provided on the substrate 2 and is a gray layer.
The upper layer 6 is formed so as to cover it. Conductor layer 9 for the preheat
An insulating layer 10 made of silicon dioxide or the like is formed between the heat generating resistor 1 and the heating resistor 1 so as to prevent energization between the electrodes 3 and 3a and the conductor layer 9. The structure on the insulating layer 10 is the same as the conventional example. The conductor layer 9 is used by generating heat with a power source 11 separate from the main heating resistor 1.

As described above, if the conductor layer 9 for preheat is formed below the heat generating portion a via the insulating layer 10 and the switch element 13 is turned on to generate heat temporarily just before the start of printing, The heat generated by the heating resistor 1 at the start of printing acts without being taken by the lower glaze layer 6 and the substrate 2, and printing can be performed at an appropriate density. Further, by adjusting the amount of heat generated by the conductor layer 9 during printing, the temperature change of the heating resistor 1 can be controlled and the density during printing can be kept constant.

[0011]

According to the present invention, since the conductor layer serving as the preheat layer is provided immediately below the heating element, the temperature of the heating element can be raised efficiently in a short time, and at the start of printing. Problems such as low density on the first line can be improved. In addition, the temperature of the heating element is controlled by adjusting the amount of heat generated in the preheat layer to control changes in the printing density during printing due to changes in the temperature of the heating element due to heat accumulation and heat dissipation on the substrate, etc. It becomes possible to keep.

[Brief description of drawings]

1A is a sectional view showing an embodiment of a thermal head according to the present invention, and FIG. 1B is a sectional view taken along line HH of FIG.

FIG. 2A is a side view showing a conventional thermal head,
(B) is a sectional view thereof.

[Explanation of symbols]

 1 Heating Resistor 2 Substrate 3, 3a Electrode 5 Heat Sink 6 Glaze Layer 7 Protective Film 9 Conductor Layer 10 Insulating Layer 11 Power Supply 13 Switch Element

Claims (1)

[Claims] 1. A thermal head comprising a heat sink and a ceramic substrate for forming a heat generating portion, a conductor layer for preheat is formed on the ceramic substrate, and an insulating layer is formed on the conductor layer. A thermal head characterized in that a heat generating portion is formed through the heat generating portion.