JPH1034994A - Thermal print head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize high speed printing while suppressing fluctuation in the resistance of a heating element or thermal stress by providing an insulation layer formed along the longitudinal direction above one side edge of an insulating substrate while covering a first heating element, and a second heating element formed on the insulation layer while being connected electrically with a common electrode and an individual electrode. SOLUTION: An insulating substrate 1 of alumina ceramic is printed, along the longitudinal direction near one side edge thereof, with ruthenium oxide paste which is then fired to form a first heating element 2. The insulating substrate 1 is then printed with glass paste except a part where a power supply body 3, formed by printing and tiring gold paste, is superposed on the first heating element 2 while covering the first heating element 2 thus forming an insulation layer 4. Furthermore, gold paste is printed and fired interdigitally on the insulation layer 4 to form a plurality of individual electrodes 5 and a common electrode 6 which are then bridged by printing and firing ruthenium oxide paste, thus forming a second heating element 7.

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, and more particularly, to a preheating (preheating) structure of a thermal printing head.

[0002]

2. Description of the Related Art As shown in a perspective view of FIG. 5, a conventional thermal print head used for electronic equipment such as a facsimile machine has a base 11 made of aluminum, a first insulating substrate 12 made of ceramic and a glass. Second insulating substrates 13 made of epoxy resin are juxtaposed. Since these two substrates are connected by the flexible substrate 14, they are juxtaposed so that their respective upper surfaces have the same height. On the entire surface of the first insulating substrate 12, a glaze layer (not shown) is formed, and on the upper surface, a heating resistor 15 and a common electrode 16 and a plurality of individual electrodes 17 are formed so as to be continuous therewith. . Then, a bonding wire 18 is attached to the individual electrode 17.
Is mounted on the surface of the first insulating substrate 12, and a connection electrode 20 connected to the driving IC 19 by the bonding wire 18 is formed on the surface of the first insulating substrate 12. . Also, the second insulating substrate 1
A conductor pattern (not shown) connected to the outside is formed on the surface of the first conductor pattern 3, and one side of the conductor pattern is a first side.
The other side is connected to a connector (not shown) connected to the outside. The protective cover 21 is fixed to the base 11 with screws 22 so that the print medium does not contact the drive IC 14 and the bonding wires 18 mounted on the first insulating substrate.

[0003]

However, in the above-described configuration of the thermal print head, the first insulating substrate on which the heating resistor 15 is formed is directly mounted on the base 11 having excellent heat dissipation. The heat energy generated for printing from the heating resistor 15 is applied to the glaze layer (not shown) of the first insulating substrate 12.
Is stored to some extent. The stored thermal energy partially contributes to printing of print data, but another part propagates through the first insulating substrate 12 and is diffused from the base 11, particularly from the side and bottom surfaces of the base 11. However, there is a problem that it takes time to reach a temperature required for printing, and a response delay occurs during high-speed printing.

On the other hand, in order to solve the above-mentioned problem, FIG.
Without changing the configuration of the conventional thermal print head shown in (1) above, the control circuit of the thermal print head is changed and the heat is always pre-heated so that the heating resistor generates heat at a temperature lower than printing. A print head is also known, but in this case, since the heating resistor constantly generates heat, the resistance value of the heating resistor easily changes, which not only adversely affects the print quality, but also uses a thermal printing head. When the ambient temperature is low, the thermal stress applied to the heating resistor increases, which has a problem that the life of the heating resistor, that is, the thermal print head is adversely affected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal printing head having a preheating structure capable of high-speed printing and having little change in resistance of a heating resistor of a thermal printing head and little thermal stress.

[0006]

In order to solve the above-mentioned problems, the invention described in claim 1 of the present application is directed to a first heating device formed along the longitudinal direction near one side edge of an insulating substrate. A resistor, an insulating layer covering the first heating resistor, and a second heating resistor formed on the insulating layer so as to be electrically connected to the common electrode and the individual electrode. And

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermal print head according to the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view and FIG. 2 is a cross-sectional view showing an embodiment of the present invention. A portion having the same configuration as that of the prior art is partially omitted, and a glaze layer (not shown) is provided on the surface. The first heating resistor 2 is formed by printing and baking a paste made of ruthenium oxide along the longitudinal direction near one side edge on the insulating substrate 1 made of alumina ceramic on which is formed. At this time, the first heating resistor 2 is formed while leaving a region where a common electrode and a power supply, which will be described later, can be formed at one end and both ends in the longitudinal direction of the insulating substrate 1. Then, a paste made of gold is printed and baked along both short side directions of the insulating substrate 1 so that both ends and a part of the first heating resistor 2 are partially stacked, thereby forming the power supply 3. The insulating layer 4 is formed by printing and baking a glass paste so as to cover the first heating resistor 2 except for the portion where the first heating resistor 2 and the first heating resistor 2 are stacked. A plurality of individual electrodes 5 and common electrodes 6 are formed by printing and baking a paste made of gold so as to face in a comb shape on the insulating layer 4, and the individual electrodes 5 and common electrodes 6 are bridged. The second heating resistor 7 is formed by printing and firing a paste made of ruthenium oxide. The common electrode 6 has a comb-tooth portion 6a facing the individual electrode 5 in a comb-tooth shape and a common pattern portion 6b. Further, a glass paste is printed and baked so as to protect these heating resistors and electrodes, thereby forming a protective layer 8, thereby forming a thermal printing head (thick film type).

In this embodiment, the glaze layer (not shown) can be omitted, and the insulating layer 4 can be used for the function of the glaze layer of the second heating resistor 7 instead. The thermal printing head having the first heating resistor 2 for preheating (preheating) having the above-described structure is supplied from the power supply 3 based on a thermistor of the thermal printing head, a sensor for detecting the ambient temperature, and printing data. Controlling the heat generation of the first heating resistor 2 by controlling an electric signal to prevent a printing delay due to a response delay at the time of high-speed printing of the thermal printing head and a printing dot reproduction defect at the time of use in a cold region. Can be.

The control of the first heating resistor 2 is performed by an electric signal supplied from the power supply 3, but a semiconductor element (not shown) connected to the individual electrode 5 connected to the second heating resistor 7.
A control circuit for the first heating resistor 2 may be formed in advance and the semiconductor element may be controlled collectively, or the power supply 3 may be supplied with an electric signal from the outside (the printer body). Good.

On the other hand, a perspective view of FIG. 3 and a sectional view of FIG. 4 show another embodiment of the present invention, in which ruthenium oxide is formed along a longitudinal direction near one side edge on an insulating substrate 1 made of alumina ceramic. The first heating resistor 2 is formed by printing and baking a paste made of gold, and a paste made of gold is applied along both short side directions of the insulating substrate 1 so that both end portions of the first heating resistor 2 are partially stacked. Is printed and fired to form the power supply 3. At this time, a region where a common electrode to be described later can be formed is left at one end and both ends of the insulating substrate 1 in the longitudinal direction, and the first
The heating resistor 2 and the power supply 3 are formed. The insulating layer 4 is formed by printing and baking a glass paste so as to cover the first heating resistor 2 except for the portion where the power supply 3 and the first heating resistor 2 are stacked. Then, the insulating substrate 1 and the insulating layer 4
A resistive layer made of Ta-SiO is formed into a thin film by a well-known sputtering method so as to cover the surface of the resistor layer (not shown). (Not shown)
Is formed, the resistor layer and the electrode layer are removed by etching to form a plurality of individual electrodes 5, a common electrode 6, and a plurality of heating resistors 7. Further, a thermal print head (thin film type) is formed by forming a thin film of a glass material made of SiO ₂ —Ta ₂ O ₅ to protect the heating resistors and the electrodes to form a protective layer 8.

In this embodiment, the insulating layer 4 is formed so as to serve also as a partial glaze layer generally formed in a thin-film thermal print head. It is possible to manufacture without changing to. In this embodiment, the power supply 3 is formed before the formation of the insulating layer 4. However, since the portion where the power supply 3 is stacked with the first heating resistor 2 is not covered with the insulating layer 4, the individual electrodes 5 and The power supply 3 may be formed by patterning by etching an electrode layer formed to form the common electrode 6.

Furthermore, in this embodiment, the first heating resistor 2 is formed by thick film forming means (printing and firing), but may be formed by thin film forming means in the same manner as the second heating resistor 7. It should be noted that the present invention is not particularly limited to the configuration of the shape, material, method, and the like described in the above-described embodiment.

[0013]

The first and second heating resistors are formed on an insulating substrate with an insulating layer interposed therebetween, and the upper layer is used for printing and the lower layer is used for remaining heat, so that it can be used at high speed printing and in cold regions. Insufficient thermal energy at the time of printing is complemented by raising the temperature of the substrate by causing the lower heating resistor to generate heat, so that the upper heating resistor only needs to perform printing based on print data. As a result, it is not necessary to constantly heat the upper heating resistor for preheating, and it is possible not only to prevent deterioration in printing quality due to a change in resistance value and to prevent the life of the heating resistor from being deteriorated due to thermal stress received from the constant heating. This has the effect of enabling high-quality printing without being affected by the ambient temperature or printing conditions (speed, etc.).

[Brief description of the drawings]

FIG. 1 is a perspective view showing a thermal print head according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a side surface of the thermal print head according to one embodiment of the present invention.

FIG. 3 is a perspective view showing a thermal print head according to another embodiment of the present invention.

FIG. 4 is a sectional view showing a side surface of a thermal print head according to another embodiment of the present invention.

FIG. 5 is a perspective view showing a conventional thermal print head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 2 ... 1st heating resistor 3 ... Power supply 4 ... Insulating layer 5 ... Individual electrode 6 ... Common electrode 7 ... Heating resistor 8 ··· Protective layer

Claims (1)

[Claims] 1. A first heating resistor formed along a longitudinal direction near one side edge of an insulating substrate, an insulating layer covering the first heating resistor, a common electrode and an individual component on the insulating layer. And a second heating resistor formed so as to be electrically connected to the electrode.