Thick film resistor material and thermal head obtained therefrom

Claim 2

A thermal head obtained by laminating a glaze layer, electrodes, a thick film resistor layer and a protective layer on an insulating substrate in this order, said resistor layer being obtained by calcining a mixed material consisting essentially of ruthenium oxide fine particles, glass fine particles having a particle size of at most 1 μm and a dispersant which disperses said fine particles and disappears by calcining, said ruthenium oxide particles having a specific surface area of 10 to 40 m 2 /g and a particle size of 1 μm as the upper limit value of particle size distribution, such that, after calcining, a uniform mutual distance between the fine particles of ruthenium oxide and uniform distribution of the fine particles of ruthenium oxide among the glass is achieved, as compared to the uniformity in mutual distance between particles and in particle distribution when the fine particles of ruthenium oxide are outside the specific surface area range of 10 to 40 m 2 /g and the upper limit value of particle size distribution of 1 μm, whereby scattering of resistance values of the thick film resistor is suppressed.

Claim 3

A thermal head according to claim 1, wherein the ruthenium oxide fine particles form a substantially uniform network in molten glass.

Claim 4

A thermal head according to claim 1, wherein said protective layer is obtained by, forming a glass coating on the resistor layer, followed by calcining.

Claim 5

A thermal head according to claim 1, wherein the substrate is an alumina plate.

Claim 6

A thermal head according to claim 1, wherein the glaze layer and the protective layer are made of glass.

Claim 7

A thermal head according to claim 1, wherein the electrodes are made of gold.

Claim 8

A thermal head obtained by laminating electrodes and a thick film resistor layer so as to overlie an insulating substrate, such that the electrodes are in between the substrate and the resistor layer, wherein the thick film resistor layer is formed by coating a material for the thick film resistor layer, the material for the thick film resistor layer consisting essentially of fine particles of ruthenium oxide; fine particles of glass which, during a calcining process of the material in forming a thick film resistor, become molten such that the material, after said calcining process, forms a network of ruthenium oxide in glass; and a dispersant which disperses these fine particles and disappears by calcining, said fine particles of glass having a particle size of at most 1 μm, said fine particles of ruthenium oxide having a specific surface area of 10 to 40 m 2 /g and a particle size of 1 μm as the upper limit value of particle size distribution, such that a uniform mutual distance between fine particles of ruthenium oxide and a uniform distribution of fine particles of ruthenium oxide among the glass particles is achieved, as compared to the uniformity in mutual distance between particles and in particle distribution when the fine particles of ruthenium oxide are outside the specific surface area range of 10 to 40 m 2 /g and the upper limit value of particle size distribution of 1 μm, whereby scattering of resistance values of the thick film resistor is suppressed.

Claim 9

A thermal head obtained by laminating electrodes and a thick film resistor layer so as to overlie an insulating substrate, such that the electrodes are in between the substrate and the resistor layer, wherein the thick film resistor layer is formed by coating a material for the thick film resistor layer, the material for the thick film resistor layer consisting essentially of fine particles of ruthenium oxide; fine particles of glass which, during a calcining process of the material in forming a thick film resistor, become molten such that the material, after said calcining process, forms a network of ruthenium oxide in glass; and a dispersant which disperses these fine particles and disappears by calcining, said fine particles of glass having a particle size of at most 1 μm, said fine particles of ruthenium oxide having a specific surface area of 10 to 40 m 2 /g and a particle size of 1 μm as the upper limit value of particle size distribution, such that a uniform mutual distance between fine particles of ruthenium oxide and a uniform distribution of fine particles of ruthenium oxide among the glass particles is achieved, as compared to the uniformity in mutual distance between particles and in particle distribution when the fine particles of ruthenium oxide are outside the specific surface area range of 10 to 40 m 2 /g and the upper limit value of particle size distribution of 1 μm, whereby scattering of resistance values of the thick film resistor is suppressed.

Claim 10

A thermal head according to claim 7, wherein the thick film resistor layer is provided overlying the electrodes, and a protective layer overlies the thick film resistor layer.

Claim 11

A thermal head according to claim 8, wherein the protective layer is a glass layer.

Claim 12

A thermal head according to claim 9, wherein a glaze layer is provided between the substrate and the electrodes.

Claim 13

A thermal head according to claim 8, wherein the thick film resistor layer covers a central portion of the electrodes.

Claim 14

A thermal head according to claim 7, wherein said material for the thick film resistor layer further consists essentially of at least one oxide filler.

Claim 15

A thermal head according to claim 12, wherein said material for the thick film resistor layer further consists essentially of at least one other electroconductive substance, for improving breakdown power characteristics.

Claim 16

A thermal head according to claim 13, wherein the at least one oxide filler and the at least one other electroconductive substance in said material for the thick film resistor layer are particles, having a particle size of at most 1 μm.

Claim 17

A thermal head according to claim 7, wherein said material for the thick film resistor layer further consists essentially of at least one other electroconductive substance, for improving breakdown power characteristics.

Claim 18

A thermal head according to claim 7, wherein a glass material of the fine particles of glass is selected from the group consisting of borosilicate glass, silicate-lead glass and crystallized glass.

Claim 19

A thermal head according to claim 16, wherein the dispersant is selected from the group consisting of resins, and solvents, that can form a paste of fine particles of ruthenium oxide and fine particles of glass.

Claim 20

A thermal head comprising electrodes and a thick film resistor, the thick film resistor consisting essentially of ruthenium oxide dispersed in glass, the ruthenium oxide forming a network in the glass, said glass being obtained from fine particles of glass having a particle size of at most 1 μm, said ruthenium oxide being obtained from fine particles of ruthenium oxide having a specific surface area of 10 to 40 m 2 /g and a particle size of 1 μm as the upper limit value of particle size distribution, such that a uniform mutual distance between the fine particles of ruthenium oxide and a uniform distribution of the fine particles of ruthenium oxide among the glass is achieved, as compared to the uniformity in mutual distance between particles and in particle distribution when the fine particles of ruthenium oxide are outside the specific surface area range of 10 to 40 m 2 /g and the upper limit value of particle size distribution of 1 μm, whereby scattering of resistance values of the thick film resistor is suppressed.

Claim 21

A thermal head comprising electrodes and a thick film resistor, the thick film resistor consisting essentially of ruthenium oxide dispersed in glass, the ruthenium oxide forming a network in the glass, said glass being obtained from fine particles of glass having a particle size of at most 1 μm, said ruthenium oxide being obtained from fine particles of ruthenium oxide having a specific surface area of 10 to 40 m 2 /g and a particle size of 1 μm as the upper limit value of particle size distribution, such that a uniform mutual distance between the fine particles of ruthenium oxide and a uniform distribution of the fine particles of ruthenium oxide among the glass is achieved, as compared to the uniformity in mutual distance between particles and in particle distribution when the fine particles of ruthenium oxide are outside the specific surface area range of 10 to 40 m 2 /g and the upper limit value of particle size distribution of 1 μm, whereby scattering of resistance values of the thick film resistor is suppressed.

Claim 22

A thermal head according to claim 18, wherein the electrodes and thick film resistor are provided on a substrate.

Claim 23

A thermal head according to claim 19, wherein the thick film resistor overlies the electrodes, and has a protective layer thereover.

Claim 24

A thermal head according to claim 20, further comprising a glaze layer provided between the substrate and the electrodes.

Claim 25

A thermal head according to claim 20, wherein the thick film resistor covers a central portion of the electrodes.

Claim 26

A thermal head according to claim 18, further consisting essentially of at least one oxide filler dispersed in the glass.

Claim 27

A thermal head according to claim 23, further consisting essentially of at least one other electroconductive substance dispersed in the glass.

Claim 28

A thermal head according to claim 18, wherein the fine particles of ruthenium oxide have a particle size less than 1 μm, as the upper limit value of particle size distribution.