JPH02163902A - Thermal head - Google Patents

Abstract

PURPOSE:To manufacture the title thermal head provided with a resistor layer in even resistor value as well as the records in excellent quality by a method wherein the resistor layer is composed of a glass matrix, metal and/or oxide of resistor component element creeping in the gaps in the atomic coupling of the matrix while the resistor component element is specified to be ruthenium. CONSTITUTION:Within the title thermal head provided with at least a pair of electrodes 3, 4, a resistor layer 2 in contact with both electrodes 3, 4 and a substrate 1 with at least an insulating surface holding the electrodes 3, 4 and the resistor 2 while the resistor layer 2 is composed of a glass matrix, metal and/or oxide of resistor element creeping in the gaps in the atomic coupling of the matrix, the resistor component element is ruthenium while the ruthenium content of the resistor layer 2 is specified to be 1-10% in weight ratio. For example, the resistor layer 2 is formed by heat treatment after forming the paste film containing the thermal cracking organic compound of the resistor component as well as the thermal cracking organic compound of the element forming the glass matrix.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermal head used in a recording device such as a facsimile or a printer, and more specifically relates to a thermal head used in a recording device such as a facsimile or a printer. Regarding improvements.

A conventional thermal head includes at least one pair of electrodes, a resistor layer in contact with both electrodes, at least the surface of which is insulating, and the surface of which is insulated. It basically consists of a substrate supporting the poles and the resistor layer, and a wear-resistant layer formed on the resistor layer. There are two types, a thin film type and a JvM type, depending on how they are made. The thin film type is one in which the electric charge, resistance layer, and wear-resistant layer are formed by puttering, vapor deposition, etc. in a vacuum.

In addition, for the thick film type, for example, a paste containing a pyrolyzable organic compound of gold), a paste containing RuO2 and glass frit, and a paste of borosilicate glass frit are printed, respectively.
By firing, a gold electrode, a resistor layer made of a glass layer in which RLI02 is dispersed, and a wear-resistant layer made of a glass layer are obtained, and a high-performance thermal head can be obtained at a lower cost than a thin film type. .

A thermal head generates heat in a specific area of a resistor layer that is in contact with a pair of electrodes by passing an electric current between the pair of electrodes, thereby heating a specific area of a recording member, such as thermal recording paper, to produce one dot. It provides a record of. Therefore, the important characteristics required of a thermal head are that the heat generated in the resistor layer is efficiently transmitted to the recording paper side, and that the heat generated in the resistor layer between the individual KM pairs normally arranged in a line is transmitted efficiently. - be kind. If the resistance of these resistor layers is non-uniform, the amount of heat generated by each of them will be different, so the density of individual recording dots recorded on the recording paper will be non-uniform, resulting in uneven shading in the recording. Quality deteriorates. This characteristic is particularly important for thermal heads for full-color printers that require gradation recording.

One of the causes of such recording density unevenness is variation in the resistance values of individual resistor dots.

In order to reduce such variations in resistance values of individual resistor dots, a trimming process is adopted in the thick film type. This process involves applying overload pulses to individual dots in the resistor layer, which causes the resistance to rise within the target range.
It is possible to reduce the distance to within 0.5 inch. On the other hand, in the case of a thin film type, the resistance value of each resistor dot can be made within ±2.6 inches by controlling the conditions for vapor deposition and sputtering to obtain the resistor. However, with a thin film head, it is difficult to further improve the current variation in resistance value, and with a thick film head, the current system has problems as described below.

The resistor layer of current thick-film thermal heads is formed by screen printing a paste consisting of resistor components RuO2, glass lift, and an organic binder, and then firing the paste. However, the starting paste was RuO2
Since it is a mixture of powder and glass powder, the resulting resistor layer will also be a mixture of the two. Even if a Ru O2 powder with a small particle size is used, it may aggregate or have poor dispersion into the glass matrix, resulting in a considerably large particle size in the resulting resistor layer. As a result, current will flow through the RuO2 powders that are in contact with each other.

Therefore, in order to obtain a resistor with a -like resistance value,
A considerable amount of Ru O2 powder is required. On the other hand, even if the dot resistance value is kept constant through trimming, the resistance value will preferentially change in the part of one resistor dot that is particularly prone to trimming, so even if the resistance value reaches the target value, In actual recording, heat is concentrated in a portion of one dot, making it impossible to obtain a normal dot shape.

Such a bias in the current path within one resistor dot is caused by non-uniform distribution of resistance values, that is, due to the RuO2 in the resistor layer.
due to non-uniform distribution of conductive elements such as

Problems to be Solved by the Invention As mentioned above, it is difficult to obtain a resistor layer with a resistance value of - with the conventional resistor layer made of a mixture of RuO2 and glass powder.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal head which eliminates the above-mentioned conventional disadvantages, has a resistor layer having a uniform resistance value, and provides recording of excellent quality.

Means for Solving the Problems The thermal head of the present invention includes at least one pair of electrodes, a resistor layer in contact with both electrodes, at least the surface of which is insulating, and the mold and the resistor layer are disposed on the surface. In the thermal head, the resistor layer is composed of a glass matrix and a metal and/or oxide of a resistor component element that has entered the atomic bond gaps of the matrix. The resistor component elements are ruthenium or ruthenium and rhodium, and the ruthenium content of the resistor layer is 1 to 10% by weight.

A preferred method for obtaining the resistor layer of the thermal head of the present invention is to print a paste film containing a pyrolyzable organic compound as a resistor component element and a pyrolyzable organic compound as an element forming a glass matrix. The organic compound in the paste is thermally decomposed by a process of forming by a spin code, drawing method, etc., and a glass matrix is formed by thermally decomposing the organic compound in the paste, and the metal and/or oxide of the resistor component element dispersed in the matrix. It consists of a step of generating a resistor layer.

The paste is preferably composed of the organic compound, a solvent that dissolves the organic compound, and an organic binder that is soluble in the solvent. In this paste, the organic compound of the resistor component element and the organic compound of the element forming the glass matrix are mixed in molecular V ratio, and by thermally decomposing them, a glass matrix is formed. oxides of the elements, metals and/or oxides of the resistor component elements are formed, and the latter metals and/or oxides are incorporated into the glass matrix formed by the fusion of the oxides. A resistor layer is formed. In the resistor layer produced in this way, the metal and/or oxide of the resistor component element is in a state of entering into the gaps between the atomic bonds of the glass matrix at the atomic or molecular level.

Therefore, the resistor layer has a very uniform composition, and the amount of resistor component elements may be smaller than conventional ones.

Figure 1 shows the relationship between the ruthenium element content of a resistor layer consisting of a glass matrix and mainly ruthenium oxides dispersed in the matrix and the variation in the resistance value of the resistor layer. . Note that the vertical axis related to the resistance value represents the value of 100×σ/R. R is the average resistance value, and σ is the standard deviation value.

In FIG. 1, A represents the characteristics of the resistor layer of the present invention, and B represents the characteristics of the conventional resistor layer. In case A, ruthenium or its oxide is dispersed in the glass matrix as a phase of several atoms or molecules, but in case B, it is dispersed as particles with a diameter of 5 μm or more. Therefore, in the case of B, Ru
When the element content is less than 10% by weight, the variation in the resistance value becomes large. On the other hand, in the case of A, the variation in resistance value is very low even if the Ru element content is low.

In the resistor layer using ruthenium, the temperature dependence of the resistance value is very large as shown in FIG. To improve this, it is better to use rhodium together. With the combination of rhodium,
The temperature dependence of the resistance value is improved as shown in FIG. 2b. Furthermore, the addition of rhodium also improves the film formability of the resistor layer. When using ruthenium and rhodium together, the weight ratio is 0 (Rh/Ru (6) is suitable.

Next, the elements that form the glass matrix are boron and silicon, which make up silicate glass.

Others include lead, which constitutes lead silicate glass, lanthanum, which constitutes lanthanum-based glass, and bismuth.

In addition to the above, other platinum group elements as necessary.

Gold, metal, nickel, chromium, zirconium, titanium, vanadium, aluminum, tantalum, etc. can also be added as resistance variable components or additive elements for improving the pulse resistance reliability of the resistor.

Thermal decomposable organic compounds of the above elements include algorates such as ethyl alkoxide and isopropoxide, fatty acid esters such as hexanoic acid esters, polycyclic organic compounds such as menthol alcoholade and esters, and rosins such as abietates. compounds, siloxanes, boric acid organic compounds, etc.

The temperature at which a paste containing these organic compounds is heated to produce a desired metal or oxide varies depending on the compound used, but is usually 500 to 800 C, preferably in an atmosphere containing oxygen.

The resistor layer according to the present invention can practically be obtained with a uniform thickness of about 0.3 to 1 μm. As described above, since the thickness is thin and there are almost no defects such as bubbles, the thermal efficiency during recording is also good.

Regarding the resistor layer according to the present invention, when the relationship between the dot resistance value and the ruthenium content was investigated using a 6mm/H solution of 1φ degree, it was found that when the film thickness was 0.3 μm, the ruthenium content was 100 to 100% by weight. 10Ω, and if the ruthenium content is outside this range, the resistance value will become very high or low, making it impractical.

Embodiment FIG. 3 is a longitudinal cross-sectional view of essential parts showing an example of the structure of a thermal head according to the present invention.

1 is a substrate having at least an insulating surface.

A steel plate with a hollow coating on the surface, an alumina substrate with a glaze layer on the surface, etc. are used. 2 is a resistor layer formed on the surface thereof. 3.4 is an electrode formed on the resistor layer 2. Usually, one electrode is a common electrode and the other is an individual electrode, and a large number of such electrode pairs are arranged in a line. Reference numeral 5 denotes a wear-resistant layer covering the surfaces of these electrodes 3.4 and the resistor layer 20, which contacts the recording paper and transmits the heat generated by the resistor layer f'LK. Prevent wear.

FIG. 4 shows another example of the structure of the thermal head.

11 is a substrate, on which electrodes 13 and 14 are formed;
After that, a resistor 812 and a wear-resistant layer 15 were formed.

Hereinafter, specific examples of the present invention will be described.

Example 1 A pair of electrode layers made of gold are formed on an alumina substrate having a glaze layer on its surface. Between these electrode layers and in contact with both electrodes, a resistor layer having a width of 360 μm is formed by printing and baking a resistor paste. Ru, R as resistor paste
h, St, B, Bi ethylhexanoates,
A mixture of ethylcellulose and terpineol (viscosity 5
0000 cp) was used. After drying, it was fired at 800'C to form a resistor layer.

A wear-resistant layer is formed on the resistor layer by printing and baking a borosilicate glass frit paste.

Example 2 On a hollow substrate having a hollow layer with a thickness of 100 μm,
Terpineol was further added to the resistance paste of Example 1 to form a paste film with a viscosity of 1000 cp using a spinner. Spinner rotation speed is 200 Orp.
It was set as m. After firing at 800'C, a resistor is formed into a predetermined pattern by photolithography. However, a mixed solution of sulfuric acid and ammonium borate was used as the etching solution.

Next, a gold layer is formed on the resistor layer by printing and baking a gold organometallic compound paste, and subsequently a stain electrode layer is formed in a predetermined pattern by photolithography. On top of this, a wear-resistant layer is formed by printing and baking a paste composed of ethyl alkoxytide of SL, B, and Pb, ethyl cellulose, and terpineol.

Example 3 A pair of electrode layers is formed on an alumina substrate having a glaze layer on its surface. A resistor layer having a width of 350 μm is formed between the 'H and pole layers by printing and baking a resistor paste.

Ru, Si as resistor paste.

B, Bi ethylhexanoate, ethyl cellulose and terpineol mixture (viscosity 60000c)
p) was used. After drying, it was fired at 80°C to form a resistor layer. A wear-resistant layer is formed on the resistor layer by printing and firing a borosilicate glass frit paste.

The characteristics of the thermal head obtained in the above examples are shown in the table. For comparison, the characteristics of K, conventional thermal configuration, and C are also listed. Comparative Example 1 is a thick film head, and Comparative Example 2 is a thin film head.

Effects of the Invention As described above, according to the present invention, a thermal head that provides excellent recording quality can be obtained.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the Ru content in the resistor layer and the variation in resistance value, Figure 2 is a diagram showing the temperature dependence of the resistance value of the resistor layer, and Figures 3 and 4 are 1 is a longitudinal cross-sectional view of a main part showing a configuration example of a thermal head of the present invention. 1.11... Substrate, 2.12... Resistor layer, 3°4.13.14... Electrode, 5.16...
...Wear-resistant layer. Name of agent: Patent attorney Shigetaka Awano and 1 other figure ~ 100 1 comment (C) Ru An's estate (%2)

Claims (2)

[Claims] (1) comprising at least one pair of electrodes, a resistor layer in contact with both electrodes, and a substrate having at least an insulating surface and supporting the electrodes and the resistor layer on the surface; In a thermal head in which the body layer is composed of a glass matrix and a metal and/or oxide of a resistor component element that has entered the atomic bond gaps of the matrix, the resistor component element is ruthenium, A thermal head characterized in that the ruthenium content of the resistor layer is 1 to 10% by weight. (2) comprising at least one pair of electrodes, a resistor layer in contact with both electrodes, and a substrate having at least an insulating surface and supporting the electrodes and the resistor layer on the surface; In a thermal head in which the body layer is composed of a glass matrix and a metal and/or oxide of a resistor component element inserted into the atomic bond gaps of the matrix, the resistor component element is ruthenium and rhodium. Yes, the ruthenium content of the resistor layer is 1 to 1 by weight.
A thermal head characterized by 10%.