Capacitance-type displacement measuring device

• US 5,920,198 A
• Filed: 09/15/1997
• Issued: 07/06/1999
• Est. Priority Date: 09/20/1996
• Status: Expired due to Term

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: Suzuki, Masamichi, Takahashi, Seigo
• Primary Examiner(s): Do, Diep N.
• Application Number:
  US08/999,748
• Time in Patent Office: 659 Days
• Field of Search: 324/660, 324/661, 324/662, 324/671, 324/683, 324/686, 324/690, 340/870.37, 341/15, 318/653, 318/661, 33/783, 33/784, 33/813, 33/825, 33/830, 33/706
• US Class Current: 324/662
• CPC Class Codes: G01B 3/18 Micrometers
• CPC Class Codes: G01D 5/2415 adapted for encoders

Abstract

A rotatable rotor 41 and a stator 51 located at a predetermined gap between outer circumferential face of the rotor 41 provided with half-cylindrical inner circumferential face are provided. The both ends of the outer circumferential face of the rotor 41 are provided with a step portion 44 to retain a predetermined gap between the opposing faces of the rotor 41 and the stator 51, and a stopper portion 45 to be abutted to both end faces of the stator in the axial direction. A forcing means 61(plate spring) are also provided to force the stator 51 to the rotor 41 so that the inner circumferential face of the stator is abutted at the step portion 44.

Claims

1. A capacitance-type displacement measuring device provided with a rotatable rotor having circular outer circumferential face, and a stator having half-cylindrical inner circumferential face located at a predetermined gap against the outer circumferential face of the rotor, wherein;

the inner circumferential face of the stator is provided with transmitting electrode group composed of plural electrode being impressed with respectively different-phased alternating signals, and a receiving electrode insulated from the transmitting electrode group, of which receive signal is inputted into measuring circuit,

and the outer circumferential face of the rotor is provided with a coupling electrode to couple capacitively with a plural of the electrode of the transmitting electrode group, characterized by;

a step portion provided on one of the outer circumferential face of the rotor and the inner circumferential face of the stator to retain a predetermined gap between the opposing faces of the rotor and the stator,

and a forcing means to force the stator to the rotor so that the rotor and the stator is abutted at the step portion.

2. A capacitance-type displacement measuring device provided with a rotatable rotor having circular outer circumferential face, and a stator having half-cylindrical inner circumferential face located at a predetermined gap against the outer circumferential face of the rotor, wherein;

the inner circumferential face of the stator is provided with transmitting electrode group composed of plural electrode impressed with respectively different-phased alternating signals, and a receiving electrode insulated from the transmitting electrode group, of which receive signal is inputted into measuring circuit,

the outer circumferential face of the rotor being provided with a coupling electrode to couple capacitively with a plural of the electrode of the transmitting electrode group, characterized by;

a step portion on both ends of the outer circumferential faces of the rotor to retain a predetermined gap between the opposing faces of the rotor and the stator, a stopper portion on both ends of the outer circumferential faces of the rotor, being abutted to both end faces of the stator in the axial direction,

and a forcing means to force the stator to the rotor so that the rotor and the stator are abutted at the step portion.

3. The capacitance-type displacement measuring device according to claim 2, wherein the step portions and the stopper portions are composed of end members attached and fixed on both ends of the rotor.

4. The capacitance-type displacement measuring device according to claim 3 wherein at least one of the end members is provided with a engaging means to engage to a rotator as a subject of displacement measuring.

5. The capacitance-type displacement measuring device according to claim 2, wherein the forcing means are composed of a plate spring to force the stator in a first direction orthogonal to a rotation axis of the rotor, an end of the plate spring being fixed, and the other end of the plate spring being abutted to the stator, the plate spring being provided with a curved portion between the fixed end and the other end, displaceable in a second direction orthogonal to the rotation axis of the rotor and also orthogonal to the first direction.

6. The capacitance-type displacement measuring device according to claim 2, wherein the forcing means is composed of a pair of plate springs, an end of the plate springs being fixed, and the other end of the plate springs being abutted to the stator, the plate spring being provided with curved portions between the fixed end and the other end, displaceable in a second direction orthogonal to the rotation axis of the rotor and also orthogonal to the first direction.

7. The capacitance-type displacement measuring device according to claim 6, wherein the pair of the plate springs are connected with each other at the fixed ends thereof.

8. The capacitance-type displacement measuring device according to claim 7, wherein a projection is provided on the stator on which the other end of the plate spring is abutted, and an engaging hole engaging with the projection is provided on each of the plate springs.

9. A displacement measuring device used for a micrometer provided with a main body having an anvil at an end, and a spindle screwed onto the other end of the main body to displace with a screw rotation thereof, to detect a displacement amount of the spindle in the axial direction,

the spindle being provided with a rotatable rotor located on the spindle, having circular outer circumferential face, and the main body being provided with a stator located at a predetermined gap against the outer circumferential face of the rotor, having half-cylindrical inner circumferential face, wherein;

the inner circumferential face of the stator is provided with transmitting electrode group, each electrode being impressed with respectively different-phased alternating signals, and a receiving electrode insulated from the transmitting electrode group, of which a receive signal is inputted into measuring circuit,

the outer circumferential face of the rotor is provided with a coupling electrode to couple capacitively with a plural of electrode of the transmitting electrode group, the both ends of the outer circumferential face of the rotor being provided with a step portion on both ends of the outer circumferential faces of the rotor to retain a predetermined gap between the opposing faces of the stator and the rotor, a stopper portion on both ends of the outer circumferential faces of the rotor to be abutted to both end faces of the stator in the axial direction,

and a forcing means to force the stator to the rotor so that the rotor and the stator are abutted at the step portion.

10. The capacitance-type displacement measuring device according to claim 9, wherein the step portion and the stopper portion are provided on end members attached and fixed at both ends of the rotor.

11. The capacitance-type displacement measuring device according to claim 10, wherein one of the end members is provided with a through-hole and through which a distal portion of a first plate spring is engaged to a groove formed on the spindle along the axial direction thereof, the base end of the first plate spring being fixed to the end member.

12. The capacitance-type displacement measuring device according to claim 11, wherein the forcing means is composed of a pair of second plate springs to force the stator in the first direction orthogonal to the rotation axial direction of the rotor having an end of the second plate springs being fixed and the other end of the second plate springs being abutted to the stator, the second plate spring being provided with curved portions between the fixed end and the other end, being displaceable in a second direction orthogonal to the rotation axis of the rotor and also orthogonal to the first direction.

13. The capacitance-type displacement measuring device according to claim 12, wherein a projection is provided on the stator on which the other end of the second plate spring is abutted, and an engaging hole to engage with the projection is provided on each of the second plate springs.