JPH07137319A - Thick film thermal head - Google Patents

Abstract

PURPOSE:To enhance productivity and to enable high speed printing and the lowering of power consumption by forming a thick film thermal head by successively laminating a heat accumulating layer composed of a resin and a heat generating layer on a substrate. CONSTITUTION:A heat accumulating layer composed of a resin is provided on a substrate and a heat generating layer is laminated on the heat accumulating layer to form a thick film thermal head. As the resin constituting the heat accumulating layer, a resin having thermal decomposition temp. higher than the forming temp. of the heat generating layer is pref. The heat generating layer is pref. constituted of a baked material of paste containing high softening point glass particles containing metal oxide, low softening point glass particles and org. vehicle. More concretely, as the resin used in the formation of the heat accumulating layer, a heat-resistant resin not thermally deformed or decomposed at the actual operation temp. of the thick film thermal head such as a polyimide resin, an epoxy resin or a phenolic resin is designated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention makes it possible for the first time to form a heat storage layer in a thick film thermal head from resin. That is, the present invention relates to a thick film thermal head using a heat storage layer as a resin.

[0002]

2. Description of the Related Art A thick film thermal head mounted in a facsimile, a printer or the like generally has a heat storage layer (glaze layer) made of glass on a substrate 1 as shown in the sectional view and the top view of FIGS. ) 2 is formed, the common electrode layer 3 and the individual electrode layer 4 are formed on the glaze layer 2, and the heat generating layer 5 is formed on the glaze layer 2 so as to straddle the common electrode layer 3 and the individual electrode layer 4. Then, the protective layer 6 made of glass or the like is further formed on the heat generating layer 5, and is manufactured as follows. First, the ceramic substrate 1
Print the glass paste on the top,
The glaze layer 2 is formed by firing at 00 ° C., a conductor paste is printed on the glaze layer 2, and the glaze layer 2 is printed at about 800 to 900 ° C.
Then, the common electrode layer 3 and the individual electrode layer 4 are patterned by firing. Next, a resistance paste prepared by pasting a metal oxide powder such as ruthenium oxide and a glass powder (glass frit) having a softening point of about 700 ° C. with an organic solvent was applied onto the glaze layer 2 and the common electrode layer 3 together. It is printed in a strip shape so as to straddle the individual electrode layer 4,
The heat generating layer 5 is formed by firing at 0 to 850 ° C., and a glass paste is printed on the heat generating layer 5 to form about 800 to 9
The protective layer 6 made of glass or the like is formed by baking at 00 ° C.

[0003]

In the past, in facsimiles, printers, etc., high-speed printing and low power consumption, that is, improvement of printing efficiency has been a technical problem, and a thermal head is required to achieve this problem. Is being improved. As one of means for improving the printing efficiency, for example, TOSHIBA ELECTRON DE
VICE NEWS December 1990 No. 27
It is known that the heat storage layer of the thermal head is formed of a resin such as polyimide, as described in pages 1 to 4, 1988 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers National Meeting, D-87 and the like. When the heat storage layer is a heat resistant resin,
As compared with the case where glass is used as the heat storage layer, the heat generated in the heat generation layer can be stored and released quickly, and as a result, the printing efficiency can be improved.

However, the above-mentioned documents are intended for a so-called thin film thermal head in which each layer in the thermal head is formed by a thin film forming method such as sputtering or vapor deposition, and a heating layer or the like is formed by printing or firing. In the thick-film thermal head for forming the resin, the resin could not be used as the heat storage layer. That is, the above-mentioned resin such as polyimide used as the heat storage layer has a temperature (thermal decomposition temperature) at which it is thermally decomposed at about 500 to 550 ° C., and decomposes at a temperature much lower than that of the conventional glass heat storage layer. In order to deform, when a heating resistor layer or the like is formed on the resin heat storage layer by sputtering or vapor deposition like a thin film thermal head, the temperature at the time of layer formation is around 300 ° C.,
Although the resin heat storage layer is not deteriorated, on the other hand, in the case of the thick film thermal head, the heat generation layer is about 80 as described above.
Since the resin heat storage layer is formed at a high temperature of 0 to 850 ° C., the resin heat storage layer is thermally decomposed and the characteristics of the resin heat storage layer are significantly deteriorated.

In the current state of the art, when a resin heat storage layer is used in a thick film thermal head, the heat generation layer is formed at a temperature of 500 ° C. or lower which is lower than the thermal decomposition temperature of the resin heat storage layer. Is considered a necessary condition. Therefore, the glass frit in the resistance paste for forming the heating layer has a lower softening point than that of the conventional one, for example, a softening point of 300 to 400 ° C., and the heating layer is fired at a temperature of 500 ° C. or less. When formed,
Although the characteristics of the resin heat storage layer are retained, the sheet resistance value of the heat generation layer changes significantly at an energy value much lower than the input energy required to operate the thermal head, and the power resistance characteristics of the thermal head It will be significantly deteriorated.

An object of the present invention is to achieve high-speed printing and low power consumption by using a resin for a heat storage layer in a thick film thermal head which is more advantageous in productivity and cost than a thin film thermal head. And

[0007]

As a result of intensive studies to achieve the above object, the present inventor has found that the heating layer in a thick film thermal head is made to have low softening point glass particles containing a metal oxide. When mixed with a paste containing point glass and an organic solvent and baked to form it, it can be formed at a relatively low temperature that does not cause deterioration of the characteristics of the heat storage layer made of a resin, and the resistance of the heat generation layer is high. It has been found that the heat generation efficiency as a thermal head can be greatly improved without deteriorating the power characteristics.

That is, the present invention relates to the following thick film thermal head. A thick film thermal head comprising a substrate, a heat storage layer formed on the substrate, and a heat generation layer formed on the heat storage layer, wherein the heat storage layer is made of resin. . In a thick film thermal head comprising a substrate, a heat storage layer formed on the substrate, and a heat generation layer formed on the heat storage layer, the heat storage layer has a thermal decomposition temperature higher than the formation temperature of the heat generation layer. The thick film thermal head as described above, which is made of a resin having: The thick film thermal head as described in the above item 1 or 2, wherein the heat generating layer is a fired body of a paste body containing high-softening point glass particles containing a metal oxide, low-softening point glass and an organic vehicle. The high softening point glass particles containing a metal oxide are those obtained by firing and crushing a paste body containing a metal and / or a metal oxide, high softening point glass particles and an organic vehicle. Thick film thermal head.

As the substrate in the present invention, those conventionally used in thermal heads can be used, and examples thereof include insulating and conductive substrates made of ceramics, stainless steel, etc. A ceramic substrate having a high coefficient of thermal expansion and a low coefficient of thermal expansion can be preferably used. The resin used for forming the heat storage layer in the present invention does not deform, flow or thermally decompose at the actual operating temperature (about 300 to 500 ° C.) of the thick film print head,
It can be used without particular limitation as long as the adhesiveness with the substrate to be used is well ensured even in repeated actual operation, and examples thereof include heat resistant resins such as polyimide resin, epoxy resin, and phenol resin. can do. One kind or two or more kinds of these resins are applied to a part or all of the above-mentioned substrate by printing or the like, and if necessary, heated and cured to form a heat storage layer.

Further, in the present invention, the heat generating layer needs to be formed by firing at a temperature at which the heat storage layer made of resin is not deteriorated, that is, at a temperature at which the resin heat storage layer is not deformed, flowed or thermally decomposed. It is preferred that the temperature be below about 500 ° C. Therefore, in the present invention, the heating layer is formed at a relatively low temperature by firing, for example, a paste body obtained by mixing high-softening point glass particles containing a metal oxide with a low-softening point glass paste. You can More specifically, as shown in FIG. 3A, a metal and / or metal oxide A, a high softening point glass frit B having a softening point of about 500 ° C. or higher, and more preferably 650 ° C. or higher, and an organic solvent. A resistance paste D containing a resin and an organic vehicle C made of a resin is fired to obtain a fired body in which a metal oxide A ′ is dispersed in a high softening point glass B ′, as shown in FIG. 3B. Then, this is crushed to form glass particles E as shown in FIG. 3 (c), and further, as shown in FIG. 3 (d), the glass particles E together with the low softening point glass frit F are
The paste body G is mixed with an organic vehicle C ′ made of an organic solvent and a resin, and the paste body G is printed on the heat storage layer as shown in FIG. A heating layer H in which the glass particles E are dispersed in the low softening point glass F ′ by firing at a temperature at which firing is possible
Can be formed. When the polyimide resin having a thermal decomposition temperature of 550 ° C. is used as the heat storage layer, the low softening point glass frit has a softening point of about 500 ° C. or less, more preferably about 300 to 400 ° C. The heating layer can be formed by firing at a temperature lower than the thermal decomposition temperature, for example, 500 ° C. The mixing ratio of the metal oxide and the high softening point glass frit can be appropriately selected depending on the desired resistance value. Further, as the resistance paste D, for example, a resistance paste conventionally used for forming a heat generating layer can be used.

The metal and / or metal oxide and the high softening point glass frit in the above resistance paste are obtained in a high softening point glass particle containing the above metal oxide as the particle size is reduced. The average particle size of the metal and the metal oxide is preferably about 5 μm or less, and more preferably about 1 μm or less, because the dispersed state of the metal oxide can be made uniform. The softening point glass frit preferably has an average particle size of about 5 μm or less, more preferably about 3 μm or less. Further, the high softening point glass particles containing the metal oxide and the low softening point glass frit dispersed in the organic vehicle together with the high softening point glass particles may be closer to a uniform mixed state as the particle size is reduced. Therefore, it is preferable that both have an average particle size of about 6 μm or less, and more preferably, the high softening point glass particles containing the metal oxide have an average particle size of about 5 μm or less and the low softening point glass frit has an average value of about 5 μm or less. The particle size is about 3 μm. By adjusting the particle size to be small in this way, it is possible to further suppress variations in the sheet resistance value of the obtained heat generating layer and to stably obtain a heat generating layer having the same characteristics.

The above metal and / or metal oxide includes
Examples thereof include metals such as ruthenium, indium, zirconium, palladium, rhodium and platinum, and oxides of these metals, and one or more of these can be used. In addition to the above-mentioned metal and / or metal oxide, an inorganic filler such as alumina may be appropriately added as needed to improve the strength of the high softening point glass particles containing the above metal oxide.

The organic vehicle used for forming the high softening point glass particles containing the metal oxide and the low softening point glass frit into a paste is burned at the firing temperature at the time of forming the heat generating layer. It can be used without particular limitation as long as it is, for example, a resin such as ethyl cellulose, rosin, terpineol, butyl carbitol acetate, using an organic solvent such as ethylene glycol, adjusted to a resin paste of appropriate viscosity,
If necessary, for example, a metal such as platinum or gold, a metal oxide such as zirconium oxide, an inorganic filler such as a ceramic such as alumina can be appropriately added and used within a range that does not significantly impair the characteristics of the heating element. You can Further, when the high-softening point glass particles containing the metal oxide and the low-softening point glass frit are mixed with an organic vehicle, the mixing ratio of the low-softening point glass frit is high-softening point containing the metal oxide. If it is too large with respect to the glass particles, the electric power withstanding property is deteriorated, or the content of the metal oxide in the obtained heat generating layer is reduced to limit the range of resistance value adjustment of the heat generating layer, and If the mixing ratio of the low softening point glass frit is too small, the adhesion of the resulting heat generating layer to the heat storage layer will decrease, and thus the metal oxide will be contained. As a mixing ratio of the high softening point glass and the low softening point glass frit, the weight ratio is the former: the latter = about 40 to 95:60 to 5.
And more preferably about 50-90: 5.
It is set to 0-10.

Further, in the present invention, when the heat generating layer is formed using the paste body adjusted as described above, the paste body is printed in multiple layers to increase the layer thickness of the heat generating layer. It is possible to improve the withstand power characteristics as a heat generating layer in the thermal head. still,
In the present invention, on the heat storage layer, a common electrode layer and an individual electrode layer which are partially overlapped with and connected to the heat generation layer to selectively heat the heat generation layer are provided, and these electrode layers are, for example, It can be formed by printing and firing an organic metal paste such as an organic gold paste, and patterning this by photolithography. If formed in this way, a temperature that does not change the characteristics and shape of the resin that is the heat storage layer (About 300 to 500 ° C. or lower).

Further, in the present invention, if necessary,
For the purpose of preventing abrasion of the heat generating layer and protecting each layer such as the heat generating layer and the heat storage layer, a protective layer may be formed at least on the heat generating layer on the substrate on which the heat generating layer is formed. The protective layer is made of, for example, Ta ₂ O ₅ or SiA.
It may be provided by forming an insulating material such as 1ON or SiO ₂ by a sputtering or vapor deposition method, printing / curing a heat resistant resin, or printing / baking a low softening point glass. If the protective layer is provided in this manner, the temperature (about 200 to 40
0 ° C.).

[0016]

EXAMPLES The features of the present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The following examples will be described with reference to FIGS. 1 and 2. (Example 1) First, on the entire surface of the substrate 10 made of alumina,
A polyimide resin having a thermal decomposition temperature of 550 ° C. was printed and thermally cured to form a heat storage layer 20 having a layer thickness of about 20 μm. Next, an organic gold paste was printed at a predetermined position on the heat storage layer 20, baked at 500 ° C., and patterned by photolithography to form a comb-shaped common electrode layer 30 and an individual electrode layer 40.

50% by weight of RuO _{2 having} an average particle size of 1 μm, and 47% by weight of a glass frit having an average particle size of 3 μm and containing SiO ₂ and PbO as main components and a softening point of 700 ° C.
3% by weight of ZrO _{2 having an} average particle size of 1 μm was mixed in an organic vehicle composed of ethyl cellulose resin and terpineol to obtain a paste body, which was fired at 850 ° C., and the fired body was crushed to obtain an average grain size. Glass particles containing ruthenium oxide having a diameter of 5 μm were obtained. Next, 87% by weight of the glass particles and SiO ₂ and P having an average particle diameter of 3 μm were used.
Glass frit 1 containing bO as a main component and having a softening point of 350 ° C. 1
3% by weight was mixed in the same organic vehicle as used above to obtain a paste. Then, this paste body was printed in a strip shape so as to extend over the common electrode layer 30 and the individual electrode layer 40, and was fired at 500 ° C. to form the heat generating layer 50.

After that, Ta ₂ O ₅ was vapor-deposited on the common electrode layer 30, the individual electrode layer 40, and the heat generating layer 50 at 300 ° C. by sputtering to form a protective film 60, thereby manufacturing a thick film thermal head. (Example 2) A heat storage layer, a common electrode layer and an individual electrode layer were formed on a substrate in the same manner as in Example 1 above. Then, glass particles containing ruthenium oxide having an average particle diameter of 5 μm were obtained in the same manner as in Example 1. 68% by weight of the glass particles and 32% by weight of a glass frit having an average particle diameter of 3 μm and having a softening point of 350 ° C. and having SiO ₂ and PbO as main components are mixed in the same organic vehicle as used above to prepare a paste body. Got This paste body was printed in a strip shape so as to extend over the common electrode layer and the individual electrode layer, and was fired at 500 ° C. to form a heat generating layer.

A thick film thermal head was manufactured in the same manner as in Example 1 below. (Example 3) A heat storage layer, a common electrode layer and an individual electrode layer were formed on a substrate in the same manner as in Example 1 above. Then, glass particles containing ruthenium oxide having an average particle diameter of 5 μm were obtained in the same manner as in Example 1. 57% by weight of the glass particles and 43% by weight of a glass frit having an average particle diameter of 3 μm and having a softening point of 350 ° C. and having SiO ₂ and PbO as main components are mixed in the same organic vehicle as used above to prepare a paste body. Got This paste body was printed in a strip shape so as to extend over the common electrode layer and the individual electrode layer, and was fired at 500 ° C. to form a heat generating layer.

A thick film thermal head was manufactured in the same manner as in Example 1 below. (Comparative Example 1) A glass paste was printed on an alumina substrate and fired at 1400 ° C to form a glass glaze layer. A conductor paste was printed on the glass glaze layer and fired at 800 ° C. The common electrode layer and the individual electrode layer were patterned by etching. Next, 40% by weight of RuO _{2 having} an average particle size of 1 μm and Si having an average particle size of 3 μm were used.
57% by weight of a glass frit containing O ₂ and CaO as main components and having a softening point of 700 ° C. and 3% by weight of ZrO ₂ having an average particle size of 1 μm were mixed in an organic vehicle composed of an ethylcellulose resin and terpineol to form a paste. Then, the paste body was printed in a strip shape on the glass glaze layer so as to extend over the common electrode layer and the individual electrode layer, and 800
A conventional thick-film thermal head was manufactured by firing at 800C to form a heating layer, printing a glass paste on the heating layer, and firing at 800 ° C to form a glass protective layer.

Comparative Example 2 A heat storage layer, a common electrode layer and an individual electrode layer were formed on a substrate in the same manner as in Example 1 above.
Then, 40% by weight of RuO ₂ having an average particle size of 1 μm, 57% by weight of a glass frit having an average particle size of 3 μm and having a softening point of 350 ° C. and having SiO ₂ and PbO as main components, and an average particle size of 1 μm
3% by weight of ZrO _{2 of} m was mixed in an organic vehicle composed of ethyl cellulose resin and terpineol to obtain a paste body, and the paste body was spread over the heat storage layer and the common electrode layer and the individual electrode layer. Printed in strips,
The heating layer was formed by firing at 500 ° C. Hereinafter, Example 1
A thick film thermal head was manufactured in the same manner as in.

[Power Withstanding Property and Power Consumption Property] By examining the rate of change of the resistance value of the heating resistor layer with respect to the input energy when the thick film thermal heads obtained in the above Examples and Comparative Examples are operated. The withstand power characteristics were tested.
The result is shown in FIG. As can be seen from FIG. 4, it is clear that the thick film thermal head of the present invention has a power withstanding characteristic similar to that of the conventional thick film thermal head. In the figure, if the average resistance value change rate on the vertical axis is within ± 15%, there is no practical problem as a thermal head.

Further, the heating efficiency of the thick film thermal head of the present invention and that of the conventional thick film thermal head are compared by the amount of input energy required to heat the heating resistor layer to a predetermined temperature, and the power consumption characteristics are compared. Was tested. As a result, it was found that the thick film thermal head of the present invention has a heat generation efficiency of about 50% higher than that of the conventional thick film thermal head, and that the thick film thermal head of the present invention can operate with low power consumption.

From the above results, in the thick film thermal head of the present invention, the heat generating layer can obtain a heat generation amount which is almost the same as the conventional one with half the input energy, and the power withstanding characteristic during actual operation is as follows. It is about twice as large as the conventional one.

[0025]

According to the present invention, since the heat storage layer in the thick film thermal head can be formed of resin, it is possible to quickly switch between heat storage and heat dissipation when the heat generating layer generates heat, and moreover, the heat generating layer. Since it is possible to reduce the input energy for generating heat to generate heat at a high temperature, it is possible to achieve high-speed printing and low power consumption in the thick film thermal head.

As described above, the thick film thermal head of the present invention is highly practical since it has realized for the first time that the heat storage layer is made of resin.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts showing the structure of a general thick film thermal head.

FIG. 2 is a top view of FIG.

FIG. 3 is a schematic view showing a manufacturing process of a paste body for forming a heat generating layer in the thick film thermal head of the present invention and a state when it is used as a heat generating layer.

FIG. 4 is a graph showing an input energy-resistance value change rate showing power withstanding characteristics of a thick film thermal head according to an example of the present invention.

[Explanation of symbols]

 10 substrate 20 heat storage layer 30 common electrode layer 40 individual electrode layer 50 heat generation layer 60 protective layer

Claims (4)

[Claims] 1. A thick film thermal head comprising a substrate, a heat storage layer formed on the substrate, and a heat generation layer formed on the heat storage layer, wherein the heat storage layer is made of resin. Thick film thermal head. 2. A thick film thermal head comprising a substrate, a heat storage layer formed on the substrate, and a heat generation layer formed on the heat storage layer, wherein the heat storage layer has a formation temperature of the heat generation layer. The thick film thermal head according to claim 1, which is made of a resin having a higher thermal decomposition temperature. 3. The thick film thermal head according to claim 1, wherein the heat generating layer is a fired body of a paste containing high-softening-point glass particles containing a metal oxide, low-softening-point glass and an organic vehicle. . 4. The high softening point glass particles containing a metal oxide are obtained by firing and crushing a paste containing a metal and / or a metal oxide, high softening point glass particles and an organic vehicle. The thick film thermal head according to claim 3.