Load cell and temperature correction of the same
First Claim
1. A load cell, comprising:
- a beam member having a thin material deformable portion thereon;
an insulator film formed directly on a surface of said beam member;
a bridge circuit formed on said insulator film and including thin film strain gauges and a zero point balance correcting resistor wherein said thin film strain gauges are formed on said film over said thin material deformable portion of said beam;
leads of thin film conductors for connection of said bridge circuit;
a span resistor member including a first substrate applied to said insulator film away from said thin material deformable portion of said beam member and a span temperature correcting thin film resistor formed on said substrate and connected to said bridge circuit, said span temperature correcting thin film resistor having a temperature coefficient; and
a zero point resistor member including a second substrate applied to said insulator film away from said thin material deformable portion of said beam member and a zero point balance temperature correcting thin film resistor formed on said substrate and connected to said bridge circuit, said zero point balance temperature correcting thin film resistor having a temperature coefficient.
1 Assignment
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Accused Products
Abstract
A load cell and a method of correcting the same are provided wherein a beam member on which an insulator film is formed is prevented from being trimmed by a laser beam upon laser trimming thereof. The load cell comprises a span resistor member and a zero point resistor member both formed separately of the beam member and including a span temperature correcting thin film resistor and a zero point balance temperature correcting thin film resistor, respectively, each of which has a temperature coefficient and is formed on a substrate. The resistor members are applied to the insulator film on the beam member and the thin film resistors are connected to a bridge circuit. The thin film resistors are trimmed with a laser beam to correct the span temperature correcting thin film resistor and the zero point balance temperature correcting thin film resistor for temperature. The substrates intercept a laser beam upon laser trimming of the thin film resistors.
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Citations
8 Claims
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1. A load cell, comprising:
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a beam member having a thin material deformable portion thereon; an insulator film formed directly on a surface of said beam member; a bridge circuit formed on said insulator film and including thin film strain gauges and a zero point balance correcting resistor wherein said thin film strain gauges are formed on said film over said thin material deformable portion of said beam; leads of thin film conductors for connection of said bridge circuit; a span resistor member including a first substrate applied to said insulator film away from said thin material deformable portion of said beam member and a span temperature correcting thin film resistor formed on said substrate and connected to said bridge circuit, said span temperature correcting thin film resistor having a temperature coefficient; and a zero point resistor member including a second substrate applied to said insulator film away from said thin material deformable portion of said beam member and a zero point balance temperature correcting thin film resistor formed on said substrate and connected to said bridge circuit, said zero point balance temperature correcting thin film resistor having a temperature coefficient. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of correcting the temperature of a load cell, comprising:
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forming an insulator film directly on a surface of a thin material deformable portion of a beam member; forming a bridge circuit of thin film strain gauges including a zero point balanced correcting resistor and leads for electric connection of said bridge circuit on said insulator film by selective etching after formation of a thin film wherein said gauges are formed on said insulator film over said thin material deformable portion of said beam member; applying to said insulator film away from said thin material deformable portion of said beam member a span resistor member on which a span temperature correcting thin film resistor having a predetermined temperature coefficient is formed on a first substrate; applying to said insulator film away from said thin material deformable portion of said beam member a zero point resistor member on which a zero point balance temperature correcting thin film resistor having a predetermined temperature coefficient is formed on a second substrate; connecting said span temperature correcting thin film resistor and said zero point balance temperature correcting thin film resistor to said bridge circuit; and trimming said two thin film resistors with a laser beam to correct the temperature of said load cell. - View Dependent Claims (8)
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Specification