JPH03208671A - Thermal head - Google Patents

Abstract

PURPOSE:To reduce the transmission of the heat from a heat generating resistance body to a glaze layer thereby to improve the thermal efficiency by laminating a heat insulative layer comprising at least one layer between the glaze layer and heat generating resistance body. CONSTITUTION:A heat insulative layer 8 of about 5mum thickness made of an oxide such as W, Mo or Os or the like is laminated on an upper surface of a glaze layer 2. The heat insulative layer 8 is changed to a film very quickly and the film is low in density. Therefore, the thermal conductivity of the heat insulative layer 8 is considerably low. When an individual power supplying layer 4b corresponding to a desired dot is energized, a heat generating part of a heat generating resistance body 3 generates heat, and the ink of an ink ribbon is melted and transferred to a paper. At this time, since the heat insulative layer 8 has a high thermal resistance, the calory resulting from the heat conduction at the heat generating resistance body 3 is hard to be transmitted to the glaze layer 2 and therefore a large amount of heat is secured to be transmitted to the printing side. The thermal efficiency is improved. The density of the printing energy is maintained high without increasing the impressing power to a thermal head.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head, and more particularly to a thermal head that is installed in a thermal printer and performs desired printing by heating with electricity based on desired printing information.

[Conventional technology]

In general, a thermal head installed in a thermal printer has, for example, a plurality of heat-generating resistors arranged linearly on an insulating substrate, and each heat-generating resistor is selectively energized and heated according to printed information. It is used to perform color recording on recording paper, or to melt ink from an ink ribbon and transfer it to plain paper.

FIG. 13 shows a conventional thermal head of this type, in which a glaze layer 2 made of glass, which functions as a heat storage layer, is formed on an insulating substrate 1 made of alumina, etc. A plurality of heating resistors 3 made of Ta2N or the like are formed on the upper surface of the resistor 2 by evaporation, sputtering, etc. and then etching to form a linear array. A common power supply layer 4a and an individual power supply layer 4b for supplying power to the heat generating resistor holes 3 are formed on both sides of the upper surface of each heat generating resistor 3, and each of these power feed layers 4a, 4b is, for example, A.4b. Made of soft metals such as Q, Cl, and Au,
It is formed into a desired pattern by vapor deposition, sputtering, or the like. Then, each of the heat generating resistors 3 is exposed between the common power supply layer 4a and the individual power supply layer 4b, and is divided into independent heat generating portions corresponding to 1 to 1 dots, and Each heat generating part is connected to each of the power supply layers 4
Heat is generated by applying a voltage between a and 4b.

Moreover, the heating resistor 3 and the power supply layer 4a, 1! Ib
The heating resistor 3 and the power supply layer 4a,
A protective layer 5 having a thickness of about 7 to 10 μm is formed to protect the film 4b. This protective layer 5 includes an oxidation-resistant layer 6 made of SiO2, etc., which protects the heating resistor 3 from deterioration due to oxidation, and has a thickness of approximately 2 μm, and is laminated on this oxidation-resistant layer 6 to prevent contact with an ink ribbon or the like. The protective layer 5 is formed of a wear-resistant layer 7 made of Ta205 or the like and having a thickness of about 5 to 8 μm, which protects the heat-generating resistor 3 and each power supply layer 4a, 4b from wear caused by the terminal portion. Covers all surfaces except for The oxidation-resistant layer 6 and the wear-resistant layer 7 of the protective layer 5 are sequentially formed by means such as sputtering, and then, in the final step, the insulating substrate 1 is divided to obtain desired thermal head chips. .

In such a conventional thermal head, the thermal head is brought into pressure contact with the paper via an ink ribbon, and the heating resistor is energized by applying electricity to the individual power supply layer 4b corresponding to a desired dot based on predetermined printing information. Desired printing is performed on the paper by melting and transferring the ink of the ink ribbon onto the paper while avoiding the heat generating section 3.

[Problem to be solved by the invention]

However, in the conventional thermal head, the heat storage property of the thermal head is controlled by changing the thickness of the glaze layer 2.
If the thickness of the glaze layer 2 is made large, the heat capacity of the glaze layer 2 will increase and the heat storage capacity will increase, making it impossible to obtain the high-speed thermal response required for high-speed printing. The thickness of the layer 2 is made thin to increase the amount of heat dissipated to the substrate, thereby ensuring thermal responsiveness for high-speed printing and preventing density unevenness in printing.

However, if the thickness of the glaze layer 2 is made thinner, the amount of heat dissipated to the substrate increases, resulting in a significant drop in thermal efficiency, making it impossible to maintain a high printing energy density, resulting in an increase in power supply, and a large This has the problem of causing significant energy loss.

In addition, the temperature control of the heating resistor 3 during high-speed printing is corrected based on the thermal history of each heating part, but this has the problem of increasing the capacity of the control circuit and increasing the manufacturing cost. are doing.

The present invention has been made in view of these points, and it is an object of the present invention to provide a thermal head that can reduce the amount of heat generated from the heating resistor transferred to the glaze layer and significantly improve thermal efficiency. It is something.

(Means for Solving the Problems) In order to achieve the above object, a thermal head according to the present invention includes forming a glaze layer on an insulating substrate, and forming a plurality of heating resistors in an array on this glaze layer. In a thermal head, a common power supply layer and an individual power supply layer for selectively supplying current to each of the heat generating resistors are formed on the heat generating resistor, and a protective layer is formed on the exposed upper surface of each of the layers. , is characterized in that at least one thermal insulating layer is laminated between the glaze layer and the heating resistor.

[For production]

According to the present invention, since the thermal insulation layer has a low heat transfer coefficient and has thermal resistance, the amount of heat generated by energizing the heating resistor becomes difficult to transfer toward the glaze layer, and this amount of heat is reduced. Since it can be efficiently transmitted to the printing side, thermal efficiency can be significantly improved, and high printing energy density can be maintained without increasing the applied power of the thermal head. Furthermore, the thickness dimension of the glaze layer can be Since there is no need to significantly deviate the glaze layer, the amount of heat stored in the glaze layer does not increase, and high high-speed thermal response can be obtained.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 12.
The same parts as in FIG. 13 will be explained using the same reference numerals.

FIG. 1 shows an embodiment of a one-terminal head according to the present invention, in which an insulating substrate 1 made of alumina or the like has
A glaze layer 2 made of glass that functions as a heat storage layer and having a thickness of approximately 40 μm is formed, and this glaze layer 2 has an approximately arcuate cross-sectional shape.

Further, on the upper surface of this glaze layer 2, an oxide such as W, MO, or Os (WO3, W4011, MOO3, O
A thermal insulating layer 8 having a film thickness of approximately 5 μm is deposited, and this thermal insulating layer 8 is made of, for example, W, MO, or OS, and is made of
It is formed by sputtering in an active gas atmosphere. This thermal insulation layer 8 is
Since the volume of the sputtered metal atoms expands three times or more due to oxidation, the film formation rate is high and the film quality is low in density, resulting in extremely low thermal conductivity.

Furthermore, a heating resistor 3 made of Ta2N or the like is formed on the upper surface of the thermal insulating layer 8, and A. l! A common power supply layer 4a consisting of
and an individual power supply layer 4b are formed. Each of these power supply bodies m4. a and 4b are formed into a pattern of a desired shape by photolithography technology, etc.
A protective layer 5 made of Si3N4 or the like is formed on the upper surfaces of the heating resistor 3 and the power supply layers 4a and 4-b.

Next, the operation of this embodiment will be explained.

In this embodiment, the thermal head is pressed against the paper via the ink ribbon, and the individual power supply layer 4b corresponding to the desired dot is energized based on predetermined printing information, thereby generating heat in the heat generating resistor 3. By generating heat in the ink ribbon and melting and transferring the ink on the ink ribbon to the paper,
Desired printing is performed on the paper.

At this time, in this embodiment, since the heat insulating layer 8 has a high thermal resistance, the heat generated in the heat generating resistor 3 when energized is difficult to be transmitted toward the glazing layer 2. This makes it possible to secure a large amount of heat transferred to the printing side, improve thermal efficiency, and maintain a high printing energy density without increasing the power applied to the thermal head. be. Furthermore, since the thermal insulating layer 8 is thin, it has a small heat capacity, and the heat transferred to the thermal insulating layer 8 is quickly radiated to the substrate via the glaze layer 2, resulting in heat accumulation that impedes high-speed printing. can be prevented. Furthermore, since the thermal insulating layer 8 is inorganic, the adhesion and heat resistance of the film are improved compared to organic materials such as polyimide.

Note that since the heat-insulating BEt 8 has relatively low hardness, a sputtered film of SiO2, Ta205, etc. may be interposed before forming the heating resistor 3 to increase the mechanical strength.

Therefore, in this embodiment, the thermal insulating layer 8 is formed, and this thermal insulating layer 8 can efficiently transmit the thermal transition during generation to the printing side, so that the thermal efficiency can be significantly increased, and the printing Energy can be used effectively, and since there is no need to increase the thickness of the glaze layer 2, the heat storage in the glaze layer 2 does not increase, achieving high high-speed thermal response. be able to. Also,
Since there is no need to perform detailed control such as thermal history correction, the capacity of the control circuit can be reduced and manufacturing can be done at low cost.

Further, FIG. 2 shows another embodiment of the present invention. In this embodiment, Tai! A thermal insulating layer 8 made of a compound and having a film thickness of approximately 5 μm is laminated, and this thermal insulating layer 8 is formed by sputtering in an 02 gas atmosphere using, for example, a Ta target. . This thermal insulating layer 8 expands 2.5 times in volume due to oxidation and becomes a low thermal conductive layer 02
By controlling the flow rate of , it is possible to form any shape from a conductive black film made of TaOx or the like to an insulating transparent film made of Ta205 or the like.

The other parts are the same as those shown in FIG. 1, so their explanation will be omitted.

In this embodiment, as in the previous embodiment, the thermal insulating layer 8 made of Ta oxide has a lower thermal conductivity and higher thermal resistance than the glaze layer 2, so that when energized in the heating resistor 3, The amount of heat generated can be efficiently transferred to the printing side, and the printing energy density can be increased without increasing the applied current to the thermal head. Furthermore, since the heat capacity of the thermal insulating layer 8 is small, the heat transferred to the thermal insulating layer 8 is quickly radiated to the substrate 1 via the glaze layer 2, thereby preventing heat accumulation that would impede high-speed printing. be able to.

Note that in this embodiment, the thermal insulating layer 81 1 is a conductive black film made of TaOx, etc.
Thermal insulation is greater than that of an insulating transparent film made of, etc.

FIG. 3 shows still another embodiment of the present invention. In this embodiment, a thermal insulating layer 8 made of porous glass and having a thickness of approximately 5 μm is provided on the upper surface of the glaze layer 2.
are laminated, and this thermal insulating layer 8 can be formed by sputtering while controlling the phase separation composition ratio by controlling the flow rate of 02 gas using, for example, a glass target having a phase separation composition. Then, the soluble layer is eluted with acid to form the porous glass. This glass is, for example, Moo-Ca, which does not contain alkali oxides.
O-A. It is known as ll 203-B203SiO2 glass. Further, since the mechanical strength of the thermal insulating layer 8 decreases due to an increase in porosity, the portion corresponding to the heating resistor 3 is made porous in a dot-like or linear-like manner.

The other parts are the same as those in each of the above embodiments. 2 Since there is, I will omit the explanation.

In this example, as in the previous example, the heat insulating layer 8 made of porous glass has lower thermal conductivity and higher thermal resistance than the glaze layer 2. The amount of heat generated can be efficiently transferred to the printing side, and the printing energy density can be increased. Furthermore, the heat transferred to the thermal insulating layer 8 is quickly dissipated, making it possible to prevent heat accumulation that would impede high-speed printing.

Incidentally, as shown in FIG. 4, on the upper surface of the thermal insulation layer 8,
If a thermal insulating layer 8a made of Ta, 3i oxide, etc. is laminated and the pores formed by making the thermal insulating R layer 8 porous are sealed, the mechanical properties of the thermal insulating layer 8 of porous glass can be improved. It is possible to strengthen the mechanical strength and also obtain higher thermal insulation properties.

Further, FIG. 5 shows another embodiment of the present invention. In this embodiment, a T
Thermal insulation layer 8 made of A205 and having a film thickness of approximately 3 μm
A is layered with v4, and on the upper surface of this thermal insulation layer 8a,
A heat reflective thermal insulation F48b made of TiO2 and having a thickness of approximately 0.2 μm is formed as a layer. Each of these thermal insulating layers 8a, 8b is formed into a multilayer structure by sequentially performing sputtering.

Note that, as shown in FIG. 6, the thermal insulating layer 8 is made of Ta.
O and TiO2 may be simultaneously sputtered to form a mixed layer having a thickness of approximately 1 to 5 μm.

The other parts are the same as those in each of the embodiments described above, so the explanation thereof will be omitted.

In this embodiment as well, the thermal insulating layer 8
Since it has lower thermal conductivity and higher thermal resistance than the glaze layer 2, the amount of heat generated by energization in the heating resistor 3 can be efficiently transferred to the printing side, and the printing energy density can be increased. . Rough, thermal insulation layer 8
The heat transferred to the printer is quickly dissipated, and it is possible to prevent heat accumulation that would be an obstacle to high-speed printing.

FIGS. 7 and 8 show a thermal head without a thermal insulation layer, a thermal head with a thermal insulation layer of only Ta 2 0 5, and a thermal head with a thermal insulation layer of Ta 2 0 5 and T i O.
This shows the results of measuring the thermal response and isothermal area of the heat generating dots 1 and 1 for the thermal head formed with the multi-layer thermal insulating layer of 2. According to these results,
A thermal head with a multi-layer thermal insulating layer of Ta2O5 and T102 has better thermal responsiveness than a normal head with no other thermal insulating layer and a normal head with a thermal insulating layer of only Ta205. It can be seen that the isothermal area is good and the isothermal area is also large.

Furthermore, FIG. 9 shows another embodiment of the present invention,
In this example, 3i02
A thermal insulating layer 8a made of Si oxide such as W, MOOS1Ta, etc. and having a film thickness of approximately 0.2 μm is laminated on the upper surface of this thermal insulating layer 8.
m. A thermal insulating layer 8b having a film J is laminated.

Each of these thermal insulators EBa, 8b is formed into a multilayer structure by sequentially performing sputtering.

15 Furthermore, as shown in FIG. 10, the thermal insulation layer 8 is made of Si.
An oxide and a mixture of oxides such as WXMOXOS and Ta may be simultaneously sputtered to form a mixed layer. Alternatively, 02 reactive sputtering may be performed using a silicide target of W, MO, or OSXTa.

The other parts are the same as those in each of the embodiments described above, so the explanation thereof will be omitted.

In this embodiment as well, the thermal insulating layer 8
Since it has lower thermal conductivity and higher thermal resistance than the glaze layer 2, the amount of heat generated by energization in the heating resistor 3 can be efficiently transferred to the printing side, and the printing energy density can be increased. can. Furthermore, the heat transferred to the thermal insulation layer 8 is quickly dissipated, and it is possible to prevent heat accumulation that would be an obstacle to high-speed printing.

Furthermore, since the thermal expansion coefficients of the glaze layer 2 and the thermal insulating layer 8b made of oxides such as W, MO, and OS1Ta are significantly different, peeling tends to occur when heat is generated. , MOXOS11 6 Since the thermal insulating layer 8a of SiO 2 with strong contact force is interposed between the thermal insulating layer 8b of oxide such as MOXOS116Ta,
It is possible to prevent the thermal insulating layer 8b from peeling off, and even when the heat generation temperature is high, stable operation can be performed.

Further, FIG. 11 shows another embodiment of the present invention,
In this example, Ta
A thermal insulating layer 8 made of an oxide of and W or MO is laminated, and this thermal insulating layer 8 is formed by using a mixed target 1 of A and W or MO, for example.
It is formed by sputtering in a two-gas atmosphere.

The other parts are the same as those shown in FIG. 1, so their explanation will be omitted.

Even in the case of d3 in the main embodiment, as in each of the above embodiments, since the thermal insulation layer 8 has a lower thermal conductivity than the glaze layer 2 and has a higher thermal resistance, the heat generated in the heating resistor 3 by energization. Enthusiasm can be efficiently transmitted to the printing side,
Printing ■Flannel: Can increase density by 1゛. moreover,
The heat transferred to the thermal insulating layer 8 is quickly radiated, thereby preventing heat accumulation that would be an obstacle to high-speed printing.

Furthermore, FIG. 12 shows another embodiment of the present invention. In this embodiment, a heat-resistant material such as polyimide or silicone resin is placed on the top surface of the glaze layer 2 at positions corresponding to heat-generating dots 1 to 1. A thermal insulating layer 8a made of highly organic material and having a thickness of approximately 1 μm is laminated, and on the upper surface of this thermal insulating layer 8a, a layer of approximately 1 μm made of Si oxide such as S + 0 2 is laminated.
Thermal insulating layer 8b functioning as a contact layer having a film thickness of μ
are layered. Further, on the upper surface of the thermal insulating layer 8b made of Si oxide, a thermal insulating layer 8C made of oxides such as W, MO, OS, Ta, etc. is laminated by sputtering.

The other parts are the same as those in each of the embodiments described above, so the explanation thereof will be omitted.

In this embodiment, as in the previous embodiments, each of the thermal insulating layers 8a, 8b, and 3c has a lower thermal conductivity and higher thermal resistance than the glaze layer 2, so that the heat-generating resistor 3 is not interrupted by energization. The generated thermal energy can be efficiently transmitted to the printing side, which can increase the printing energy density.

Roughly, the heat transferred to the thermal insulation layer 8 is quickly radiated,
It is possible to prevent heat accumulation, which is a hindrance to high-speed printing. In addition, in this embodiment, a thermally insulating layer 8b made of SiO2 with strong adhesive strength is interposed between the glaze layer 2 and the thermally insulating layer 8C made of Ta oxide, and an organic thermally insulating layer 8a is interposed. Since it is formed only in a part, the heat insulation R layer 8
Peeling of C can be effectively prevented, and stable operation can be performed even when the heat generation temperature is high. Also,
The organic thermal insulating layer 8a can be formed over the entire surface to form a thermal head.

Note that the present invention is not limited to the above-mentioned embodiments, and various changes can be made as necessary.

〔Effect of the invention〕

As described above, in the 4 normal head according to the present invention, the amount of heat from the heat generating resistor in the heat insulating layer is difficult to be transmitted in the direction of the glaze, and this heat peak is efficiently transferred to the side marked with 1. Since the thermal efficiency can be significantly improved, a high printing energy density can be maintained without increasing the power applied to the thermal head. Further, since there is no need to increase the thickness of the glaze layer, the amount of heat stored in the glaze layer does not increase, and it is possible to obtain high high-speed thermal response.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the thermal head according to the present invention, FIG. 2 is a longitudinal cross-sectional view showing another embodiment of the present invention, and FIG. 3 is a longitudinal cross-sectional view showing another embodiment of the present invention. FIG. 4 is a longitudinal sectional view showing another embodiment of the invention, FIG. 5 is a longitudinal sectional view showing another embodiment of the invention, and FIG. 6 is a longitudinal sectional view showing another embodiment of the invention. 7 is a diagram showing the measurement results of thermal responsiveness of various thermal heads, and FIG. 8 is an explanatory diagram showing the measurement results of the isothermal area of the heating resistor of various thermal heads.
FIG. 9 is a longitudinal section 20 showing another embodiment of the invention, FIG. 10 is a longitudinal section showing another embodiment of the invention, and FIG. 11 is a longitudinal section showing another embodiment of the invention. FIG. 12 is a vertical sectional view showing another embodiment of the present invention, and FIG. 13 is a vertical sectional view showing a conventional thermal head. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Glaze layer, 4... Power feeder layer, 5... Protective layer, 8... Heat insulation layer.

Claims (1)

[Claims] A glaze layer is formed on an insulating substrate, a plurality of heat generating resistors are formed in an array on the glaze layer, and a common power supply layer is provided on the heat generating resistor to selectively conduct electricity to each of the heat generating resistors. In a thermal head in which individual power supply layers are formed and a protective layer is formed on the exposed upper surface of each of the layers, at least one thermal insulating layer is laminated between the glaze layer and the heating resistor. Thermal head is characterized by: