Load cell having thin film strain gauges

Claim 2

A load cell comprising: a beam body; a coating film of heat-resistant insulating resin formed on one surface of said beam body, said coating film having a substantially flat surface; and a load cell element formed on said substantially flat surface of said coating film; said load cell element including first and second power source terminals, first and second output terminals, a first strain gauge resistor and a first bridge balancing resistor connected in series between said first power source terminal and said first output terminal, a second strain gauge resistor and a second bridge balancing resistor connected in series between said first power source terminal and said second output terminal, a third strain gauge resistor connected between said second power source terminal and said first output terminal, and a fourth strain gauge resistor connected between said second power source terminal and said second output terminal, wherein a resistive layer is formed over a pattern region including said first to fourth strain gauge resistors, said first and second bridge balancing resistors and connecting means for connecting these resistors, and a conductive layer is formed on said resistive layer over a pattern area of the connecting means.

Claim 3

A load cell according to claim 1, wherein said resistive layer is formed of Nichrome.

Claim 4

A load cell according to claim 1, wherein said first and second bridge balancing resistors each include at least one ladder-type resistive element.

Claim 5

A load cell according to claim 1, 2 or 3, which further comprises a further coating film of heat-resistant insulating resin covering said load cell element.

Claim 6

A load cell comprising a beam body, an insulating film formed on one surface of the beam body and a load cell element formed on the insulating film, said load cell element including first and second power source terminals, first and second output terminals, a first strain gauge resistor and a first bridge balancing resistor connected in series between said first power source terminal and first output terminal, a second strain gauge resistor and a second bridge balancing resistor connected in series between said first power source terminal and second output terminal, a third strain gauge resistor connected between said second power source terminal and first output terminal, a fourth strain gauge resistor connected between said second power source terminal and second output terminal, and a first temperature compensating resistor connected to the power source terminal and having a positive temperature coefficient of resistance, wherein a first resistive layer is formed over a region including said first to fourth strain gauge resistors, first and second bridge balancing resistors, first temperature compensating resistor, and connecting means for connecting these resistors, a second resistive layer having a lower resistivity than the resistivity of said first resistive layer is formed on said first resistive layer over a pattern region including said first temperature compensating resistor and connecting means, and that a conductive layer is formed on said second resistive layer over a pattern region of said connecting means.

Claim 7

A load cell comprising a beam body, an insulating film formed on one surface of the beam body and a load cell element formed on the insulating film, said load cell element including first and second power source terminals, first and second output terminals, a first strain gauge resistor and a first bridge balancing resistor connected in series between said first power source terminal and first output terminal, a second strain gauge resistor and a second bridge balancing resistor connected in series between said first power source terminal and second output terminal, a third strain gauge resistor connected between said second power source terminal and first output terminal, a fourth strain gauge resistor connected between said second power source terminal and second output terminal, and a first temperature compensating resistor connected to the power source terminal and having a positive temperature coefficient of resistance, wherein a first resistive layer is formed over a region including said first to fourth strain gauge resistors, first and second bridge balancing resistors, first temperature compensating resistor, and connecting means for connecting these resistors, a second resistive layer having a lower resistivity than the resistivity of said first resistive layer is formed on said first resistive layer over a pattern region including said first temperature compensating resistor and connecting means, and that a conductive layer is formed on said second resistive layer over a pattern region of said connecting means.

Claim 8

A load cell according to claim 5, which further comprises a second temperature compensating resistor connected in series with said first strain gauge resistor and first bridge resistor between said first power source terminal and first output terminal and having a positive temperature coefficient of resistance, and a third temperature compensating resistor connected in series with said second strain gauge resistor and second bridge balancing resistor between said first power source terminal and second output terminal and having a positive temperature coefficient of resistance, wherein said second and third temperature compensating resistors are constituted by the lamination of said first and second resistive layers.

Claim 9

A load cell according to claim 6, wherein said first to third temperature compensating resistors, and first and second bridge balancing resistors and each include at least one ladder-type resistor element.

Claim 10

A load cell according to claim 6 or 7, wherein said first and second resistive layers and conductive layer are respectively made of Nichrome, titanium and gold.

Claim 11

A load cell according to claim 6 or 7, wherein said first and second resistive layers and conductive layer are respectively formed of Nichrome, nickel and alminum.

Claim 12

A load cell according to any one of claims 5, 6 or 7, which further comprises a span adjustment resistor connected in parallel with said first temperature compensation resistor.

Claim 13

A load cell according to claim 10, wherein said first temperature compensating resistor, first and second bridge balancing resistors and span adjustment resistor each include at least one ladder-type resistor element.

Claim 14

A load cell according to claim 11, which further comprises an insulating film covering said load cell element.

Claim 15

A load cell according to claim 10, which further comprises an insulating film covering said load cell element.

Claim 16

A load cell according to any one of claims 5 or 7, which further comprises an insulating film covering said load cell element.