Strain gauge pattern to prevent variation due to temperature

Patent metadata

Field	Value
Publication number	US-11353373-B2
Application number	US-202016887352-A
Country	US
Kind code	B2
Filing date	May 29, 2020
Priority date	May 29, 2020
Publication date	Jun 7, 2022
Grant date	Jun 7, 2022

Abstract

A strain gauge includes first and second substrates spaced apart from one another. A first flexible printed circuit board portion is in contact with a top side of the first and second substrates, and has a first Wheatstone bridge formed therein. The first flexible printed circuit board portion positions the first Wheatstone bridge such that two resistors of the first Wheatstone bridge are positioned to span from the top side of the first substrate to the top side of the second substrate. A second flexible printed circuit board portion is in contact with a bottom side of the first and second substrates, and has a second Wheatstone bridge formed therein. The second flexible printed circuit board positions the second Wheatstone bridge such that two resistors of the second Wheatstone bridge are positioned to span from the bottom side of the first substrate to the bottom side of the second substrate.

First claim

The invention claimed is:

1. An electronic device, comprising:
a strain gauge comprising:
a substrate layer comprised of first and second substrates lying in a same plane but spaced apart from one another; and
a flexible printed circuit board including first and second Wheatstone bridges, the flexible printed circuit board being wrapped about an end of the substrate layer such that the flexible printed circuit board is in contact with both a top side of the first and second substrates and a bottom side of the first and second substrates;
wherein the flexible printed circuit board positions the first Wheatstone bridge such that two resistors of the first Wheatstone bridge are positioned such that these two resistors span from the top side of the first substrate to the top side of the second substrate, and such that remaining resistors of the first Wheatstone bridge are positioned solely on the top side of the first substrate; and
wherein the flexible printed circuit board positions the second Wheatstone bridge such that two resistors of the second Wheatstone bridge are positioned such that these two resistors span from the bottom side of the first substrate to the bottom side of the second substrate, and such that remaining resistors of the second Wheatstone bridge are positioned solely on the bottom side of the first substrate.

2. The electronic device of claim 1 , further comprising a strain gauge controller configured to:
measure a first voltage difference between first and second outputs of the first Wheatstone bridge;
measure a second voltage difference between first and second outputs of the second Wheatstone bridge;
determine a voltage differential between the first and second Wheatstone bridges as a difference between the first voltage difference and the second voltage difference.

3. The electronic device of claim 2 , wherein the strain gauge controller is configured to determine a magnitude and direction of force applied to the strain gauge from the determined voltage differential between the first and second Wheatstone bridges resistors.

4. The electronic device of claim 1 , wherein the first and second Wheatstone bridges are coupled between a supply voltage and ground.

5. The electronic device of claim 1 , wherein the first Wheatstone bridge comprises:
a first resistor positioned so as to span from the top side of the first substrate to the top side of the second substrate;
a second resistor positioned so as to be positioned solely on the top side of the first substrate;
a third resistor positioned so as to span from the top side of the first substrate to the top side of the second substrate; and
a fourth resistor positioned so as to be positioned solely on the top side of the first substrate;
wherein the first and second resistors are coupled in series between a supply voltage and ground, with a first output of the first Wheatstone bridge being electrically connected between the first and second resistors; and
wherein the third and fourth resistors are coupled in series between the supply voltage and ground, with a second output of the first Wheatstone bridge being electrically connected between the third and fourth resistors.

6. The electronic device of claim 5 , wherein the first and fourth resistors are positioned physically parallel to one another; and wherein the second and third resistors are positioned physically parallel to one another.

7. The electronic device of claim 1 , wherein the second Wheatstone bridge comprises:
a fifth resistor positioned so as to span from the bottom side of the first substrate to the bottom side of the second substrate;
a sixth resistor positioned so as to be positioned solely on the bottom side of the first substrate;
a seventh resistor positioned so as to span from the bottom side of the first substrate to the bottom side of the second substrate; and
an eighth resistor positioned so as to be positioned solely on the bottom side of the first substrate;
wherein the fifth and sixth resistors are coupled in series between a supply voltage and ground, with a first output of the second Wheatstone bridge being electrically connected between the fifth and sixth resistors; and
wherein the seventh and eighth resistors are coupled in series between the supply voltage and ground, with a second output of the second Wheatstone bridge being electrically connected between the seventh and eighth resistors.

8. The electronic device of claim 7 , wherein the sixth and seventh resistors are positioned physically parallel to one another; and wherein the fifth and eighth resistors are positioned physically parallel to one another.

9. A strain gauge, comprising:
a substrate layer comprised of first and second substrates spaced apart from one another; and
a first flexible printed circuit board portion in contact with a top side of the first and second substrates, the first flexible printed circuit board portion having a first Wheatstone bridge formed therein;
wherein the first flexible printed circuit board portion positions the first Wheatstone bridge such that two resistors of the first Wheatstone bridge are positioned so as to span from the top side of the first substrate to the top side of the second substrate; and
a second flexible printed circuit board portion in contact with a bottom side of the first and second substrates, the second flexible printed circuit board portion having a second Wheatstone bridge formed therein;
wherein the second flexible printed circuit board portion positions the second Wheatstone bridge such that two resistors of the second Wheatstone bridge are positioned so as to span from the bottom side of the first substrate to the bottom side of the second substrate.

10. The strain gauge of claim 9 , wherein the first and second Wheatstone bridges are coupled between a supply voltage and ground.

11. The strain gauge of claim 9 , wherein the first Wheatstone bridge comprises:
a first resistor positioned so as to span from the top side of the first substrate to the top side of the second substrate;
a second resistor positioned so as to be positioned solely on the top side of the first substrate;
a third resistor positioned so as to span from the top side of the first substrate to the top side of the second substrate; and
a fourth resistor positioned so as to be positioned solely on the top side of the first substrate;
wherein the first and second resistors are coupled in series between a supply voltage and ground, with a first output of the first Wheatstone bridge being electrically connected between the first and second resistors; and
wherein the third and fourth resistors are coupled in series between the supply voltage and ground, with a second output of the first Wheatstone bridge being electrically connected between the third and fourth resistors.

12. The strain gauge of claim 11 , wherein the first and fourth resistors are positioned physically parallel to one another; and wherein the second and third resistors are positioned physically parallel to one another.

13. The strain gauge of claim 9 , wherein the second Wheatstone bridge comprises:
a fifth resistor positioned so as to span from the bottom side of the first substrate to the bottom side of the second substrate;
a sixth resistor positioned so as to be positioned solely on the bottom side of the first substrate;
a seventh resistor positioned so as to span from the bottom side of the first substrate to the bottom side of the second substrate; and
an eighth resistor positioned so as to be positioned solely on the bottom side of the first substrate;
wherein the fifth and sixth resistors are coupled in se

Assignees

• St Microelectronics Asia Pacific Pte Ltd

Inventors

• Kim Min Sang
• Yun Chan Hyuck
• Hong Sa Hyang
• Son Ju Hyun

Classifications

• G01L1/2281

  for temperature variations · CPC title

• G06F3/0418

  for error correction or compensation, e.g. based on parallax, calibration or alignment · CPC title

• G01L1/2262 Primary

  involving simple electrical bridges · CPC title

• G06F3/0414

  using force sensing means to determine a position · CPC title

• G06F3/045

  using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact · CPC title