US 5,326,982 A · Analogue displacement sensor

Abstract

The invention relates to an analogue sensor for sensing deviation from a normal position in at least two directions. The sensor senses dimensions in at least one direction and for this purpose it has a ball (52) at the tip of a measuring stick (51), which is resiliently mounted in such a manner that it can move essentially about a center. It is the deviation of the tip from its normal position which is to be indicated. The stick has a sensor portion (8, 9; 54, 55; 71, 72) placed in a sensor unit, in such a manner that the sensor portion, upon external displacing force upon the measuring tip in any direction can be advanced from a normal position, essentially about a central point (CM; CM') and is returnable to the normal position by means of a force device (3; 21; 30; 53; 73; FIGS. 7A-7C, FIGS. 9A, 9B). The advancement from the normal position about the central point is indicated to provide a measure of the deviation. Thus the sensor provides angular sensing for displacement forces of said sensor tip acting in a plane perpendicular to a symmetry axis of the sensor and a linear sensing for a displacement force acting on the tip axially of the sensor.

Claims33

Dependent claims

A sensor for sensing displacement of a measuring tip which contacts an obstacle comprising:

a) a mechanical sensing unit including a stick having said measuring tip at one end thereof;
b) suspension means in said mechanical sensing unit suspending said stick to permit angular motion in relation to an axis of said sensor in several angular directions around said axis and about a central point, and to permit axial motion along said axis of the sensor, in order to permit motion detection in three dimensions;
c) means to force said stick towards a position which represents a neutral position for said measuring tip in response to a force which displaces said measuring tip;
d) sensing means including a part movable with said stick and a stationary part for angular sensing of the direction and size of a displacement of said sensor tip from said neutral position acting in a plane perpendicular to said symmetry axis of the sensor;
e) said sensing means being adapted to sense direction and size of displacements in the axial direction from said neutral position as well as said angular displacement sensing.

2 more elements

A sensor for sensing displacement in a plurality of directions of a measuring tip from a neutral position comprising:

a) a stationary arrangement including for each sensing direction a pair of electrode plates, receiving individual alternating voltages across each electrode plate and ground, said individual supply voltages for a respective pair of electrode plates having the same frequency but opposite phases, said supply voltages for different pairs of electrode plates for sensing different directions all having different frequencies;
b) a moving unit rigidly joined to said measuring tip and supported in said stationary arrangement, said moving unit including sensing electrode plate means having at least one sensing electrode plate common for all said sensing directions for which deviation is to be indicated;
c) a direction separator circuit which receives output signals from said sensing electrode plate means, said direction separator circuit including, for each direction to be sensed, a phase detector for sensing the phase of a respective sensing supply voltage, said phase detector processing a signal having the frequency of the supply voltages of the pair of electrode plates belonging to the respective direction;
d) each individual phase detector providing a processed output signal representing displacement of said measuring tip from its neutral position in a respective measuring direction.

1 more element

A sensor for sensing displacement of a measuring tip from a neutral position in a plurality of sensing directions comprising:

a) a stationary arrangement including for each sensing direction at least a pair of voltage supplying electrode plates, each voltage supplying electrode in each pair receiving an individual alternating voltage between said electrode plate and ground, said individual supply voltages for each pair having the same frequency but opposite phases, two of said supply voltages having the same frequency and phase displaced 90.degree. to each other, and a remaining supply voltage having a different frequency;
b) a moving unit rigidly joined to said measuring tip and supported by said stationary arrangement, said moving unit including sensing electrode plate means including at least one sensing electrode plate common for all said sensing directions for which displacement is to be sensed;
c) a direction separator circuit to which a signal from said sensing electrode plate means is fed, said direction separator circuit including, for each direction to be sensed, a separate phase detector for sensing the supply voltage frequency and phase for a respective direction said phase detector signal processing said signal using the supply voltages of the pair of voltage supplying electrode plates belonging to the respective direction;
and
d) each phase detector providing a processed output signal representing the displacement of said measuring tip from its neutral position in a respective direction.

2 more elements

A sensor for sensing displacement of a measuring tip from a neutral position comprising:

a) a moving unit including for each sensing direction at least a pair of supplying electrode plates, each supplying electrode plate in each of said pair receiving an individual alternating voltage between said electrode plate and ground, said individual supply voltages for each pair of supply electrodes having the same frequency but opposite phases, said supply voltages for said different sensing directions having different frequencies;
b) a stationary arrangement supporting said moving unit including sensing electrode plate means having at least one sensing electrode plate common for all of said sensing directions;
c) a direction separator circuit connected to said sensing electrode plate means, said direction separator circuit including, for each direction to be sensed, an individual phase detector connected to receive a supply voltage frequency and phase for a respective sensing direction, said phase detector processing a signal from said sensing electrode plate means using the supply frequency of the supply voltages of the pair of supplying electrode plates belonging to the sensed direction;
d) each individual phase detector supplying a processed signal having a certain relation to the displacement of said measuring tip from its neutral position.

1 more element

A device for positioning a probe of a coordinate measuring machine, said probe having an analogue sensor for sensing a displacement of the probe when it touches an obstacle, comprising:

a) a first force supplier portion joined to a part of the sensor which moves, and a second force supplier portion joined to a stationary part of the sensor, said first and second force supplier portions forming a positioning device which operates in response to a control signal for moving said sensor movable part with respect to said sensor stationary part from a neutral position;
b) control means providing electrical control signals to said position device to set said sensor predisplacement from a neutral position before said sensor touches said obstacle, said control means receiving the measuring signals from said sensing means and providing a control signal in response to touching of said obstacle.

Dependencies are inferred from the claim text.

Analogue displacement sensor

Life of this patent

Analogue displacement sensor

Life of this patent

Abstract

Claims33