Displacement sensor for force indicating caliper

• US 9,417,094 B2
• Filed: 02/28/2014
• Issued: 08/16/2016
• Est. Priority Date: 02/28/2014
• Status: Active Grant

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: Cook, Ted Staton, Jansson, Bjorn E. B.
• Primary Examiner(s): Smith, R. A.
• Application Number:
  US14/194,320
• Publication Number:
  US 20150247742A1
• Time in Patent Office: 900 Days
• Field of Search: 337/06, 337/84, 324/207.17, 324/207.24
• US Class Current: 1/1
• CPC Class Codes: G01B 3/205 provided with a counter for digital indication of the measured dimension
• CPC Class Codes: G01B 5/00 Measuring arrangements characterised by the use of mechanical techniques
• CPC Class Codes: G01D 5/12 using electric or magnetic means G01D5/06 takes precedence

Abstract

A caliper including a scale member, a slider, a slider displacement sensor and a force sensing arrangement. The force sensing arrangement is configured to provide a signal indicative of a measurement force, and includes elements fabricated on the same circuit board as the slider displacement sensor. In one implementation, the force sensing arrangement includes drive and sense coils that are fabricated in one or more metal layers of the circuit board. A signal modulating element (e.g., a metal core) is also included which is attached to a force actuator which moves in accordance with the amount of measurement force that is being applied. The force actuator moves relative to the linearly displaced coils and the attached signal modulating element affects the inductive coupling between the coils. The resulting signals from the coils may be utilized to determine the position of the signal modulating element and the corresponding measurement force.

Claims

1. An electrically powered caliper, comprising:

a scale member including a first measuring surface to be located against a workpiece during a measurement;

a slider including a second measuring surface to be located against a workpiece during a measurement;

a slider displacement sensor configured to provide a position signal responsive to changes in a position of the slider along the scale member, the slider displacement sensor comprising a slider conductive signal sensing element fabricated on a circuit board carried on the slider;

a measurement force sensing arrangement located on the slider, the measurement force sensing arrangement comprising;

a force actuator that moves relative to the circuit board;

a force element displacement sensor comprising;

at least one force element conductive signal sensing element that is fixed relative to the circuit board and that is fabricated in a first metal layer of the circuit board;

at least one signal modulating element coupled to the force actuator and located proximate to the at least one force element conductive signal sensing element; and

a force sensing circuit located on the circuit board and coupled to the at least one force element conductive signal sensing element.

2. The caliper of claim 1, wherein the measurement force sensing arrangement is configured to provide a force signal responsive to changes in a measurement force exerted on a workpiece by a user through at least one of the first and second measuring surfaces during a measurement procedure.

3. The caliper of claim 2, wherein the force actuator comprises a rigid element coupled to a force spring rate spring having a dimension that is altered by a user through the force actuator to vary the measurement force.

4. The caliper of claim 3, wherein the at least one signal modulating element is coupled to the force actuator, and is configured to move corresponding to the altered dimension and proximate to the at least one force element conductive signal sensing element.

5. The caliper of claim 1, wherein the force sensing circuit is responsive to a position of the at least one signal modulating element relative to the at least one force element conductive signal sensing element.

6. The caliper of claim 5, wherein the at least one force element conductive signal sensing element comprises a variable inductance element having an inductance that depends on the position of the at least one signal modulating element.

7. The caliper of claim 6, wherein the force element displacement sensor further comprises at least one inductive drive element which is inductively coupled to the at least one variable inductance element, wherein the inductive coupling depends on the position of the at least one signal modulating element.

8. The caliper of claim 7, wherein the at least one signal modulating element comprises at least one of a non-ferrous conductor or a ferrite material.

9. The caliper of claim 7, wherein the at least one variable inductance element comprises at least two planar coils fabricated in the first metal layer or a second metal layer of the circuit board carried on the slider.

10. The caliper of claim 9, wherein the at least two planar coils are symmetric with respect to one another.

11. The caliper of claim 10, wherein the at least one signal modulating element covers approximately half of each of the at least two planar coils when in a rest position.

12. The caliper of claim 7, wherein the at least one variable inductance element comprises a planar signal coil and the at least one inductive drive element comprises a planar drive coil that is fabricated in the first metal layer or a second metal layer of the circuit board carried on the slider.

13. The caliper of claim 12, wherein:

the planar signal coil and the planar drive coil are configured to surround a shared area;

the circuit board comprises two layers; and

the planar signal coil and the planar drive coil are fabricated in the same metal layer of the circuit board.

14. The caliper of claim 12, wherein:

the planar signal coil and the planar drive coil are configured to surround a shared area;

the circuit board comprises four layers; and

the planar signal coil and the planar drive coil are fabricated in different metal layers of the circuit board.

15. The caliper of claim 1, wherein:

the circuit board carried on the slider abuts the slider at a mounting region of the circuit board;

the slider conductive signal sensing element of the slider displacement sensor overlaps the scale member in a scale region located in a first lateral direction away from the mounting region; and

the at least one force element conductive signal sensing element of the force element displacement sensor is arranged in a region located in the opposite lateral direction away from the mounting region.

16. An electrically powered caliper, comprising:

a scale member including a first measuring surface to be located against a workpiece during a measurement;

a slider including a second measuring surface to be located against a workpiece during a measurement;

a slider displacement sensor configured to provide a position signal responsive to changes in a position of the slider along the scale member, the slider displacement sensor comprising at least one displacement sensor component that is fabricated in a first metal layer on a printed circuit board that is carried on the slider; and

a measurement force sensing arrangement located on the slider and configured to provide a force signal responsive to changes in a measurement force exerted on a workpiece by a user through at least one of the first and second measuring surfaces during a measurement procedure, the measurement force sensing arrangement including a force element displacement sensor comprising at least one displacement sensor component that is fabricated in the first metal layer or a second metal layer on the printed circuit board that is carried on the slider.

17. The caliper of claim 16, wherein the measurement force sensing arrangement comprises:

a force actuator comprising a rigid element coupled to a force spring rate spring having a dimension that is altered by a user through the force actuator to vary the measurement force; and

at least one signal modulating element that is coupled to the force actuator, and that is configured to move corresponding to the altered dimension and proximate to the at least one displacement sensor component of the force element displacement sensor that is fabricated in the first metal layer or the second metal layer on the printed circuit board.

18. The caliper of claim 16, wherein:

the circuit board carried on the slider abuts the slider at a mounting region of the circuit board;

the at least one displacement sensor component of the slider displacement sensor that is fabricated in the first metal layer on the printed circuit board overlaps the scale member in a scale region located in a first lateral direction away from the mounting region; and

the at least one displacement sensor component of the force element displacement sensor that is fabricated in the first metal layer or the second metal layer on the printed circuit board is arranged in a region located in the opposite lateral direction away from the mounting region.

19. The caliper of claim 16, wherein the measurement force sensing arrangement includes a force sensing circuit located on the circuit board and coupled to the at least one displacement sensor component of the force element displacement sensor that is fabricated in the first metal layer or the second metal layer on the printed circuit board.