Precision inclinometer

Claim 2

An inclinometer providing a numerical readout, characterised in that it comprises a housing (10) having at least one reference surface (11), power supply means (20) for energising the inclinometer, sensor means (27) mounted in the housing and responsive to the influence of terrestrial gravitational force and disposed for gravity responsive output as a function of orientation of the reference surface relative to the horizontal, signal means coupled to the sensor (27) for energising the sensor to provide the gravity responsive output, detector means (29-32) responsive to the output, for providing a signal when the sensor is inclined with respect to the horizontal, and numerical indicator means (35) coupled to the detector means for providing a numerical output proportional to the sensed inclination.

Claim 3

An inclinometer according to claim 1, characterised in that the sensor means (27) comprises a liquid level, having an arcuate fluid-tight housing, partially filled with a suitable conductive liquid, and provided with a plurality of electrical contacts (a, b, c) for contacting said liquid, at least two of the contacts (a, b) being adapted for connection to the signal source, and at least one contact (c) other than the two contacts being centrally disposed between the two contacts and adapted for connection to the detector means (29-32).

Claim 4

An inclinometer according to claim 1, characterised in that the sensor means (27) comprises a toroidal electrolytic sensor having a housing containing an electrolytic fluid at least partially immersing a plurality of arcuate shaped electrodes disposed within the housing.

Claim 5

An inclinometer according to claim 1, characterised in that the sensor means (27) comprises a pendulum member and electrical pickoff means, the pickoff providing a signal responsive to the inclination of the pendulum.

Claim 6

An inclinometer according to claim 4, characterised in that the pickoff means are inductive, capacitive or resistive.

Claim 7

An inclinometer according to claim 1, characterised in that the sensor means comprises a pendulum member and optical pickoff means.

Claim 8

An inclinometer according to any of the preceding claims, characterised in that it further comprises low battery monitoring means (36), low battery display driver means (37), responsive to the monitoring means, for energising a low battery indicator in the numerical indicator means (35) when the power supply provides a voltage which has decreased below a predetermined value.

Claim 9

An inclinometer according to any of the preceding claims, characterised in that it further comprises means for biasing the signal means so that the sensor (27) may be calibrated for null errors in orientation with respect to the reference surface (11).

Claim 10

An inclinometer according to any of the preceding claims, characterised in that the sensor means (27), the signal means, the detector means (29-32) and the numerical indicator means (35) are so constructed and arranged to provide substantially linear operation over a predetermined range.

Claim 11

An inclinometer according to claim 9 characterised in that it is calibrated to provide a substantially linear digital readout of slope in units of vertical displacement versus horizontal distance, or in angular units.

Claim 12

An inclinometer according to any of the preceding claims, characterised in that the numerical indicator means comprises a liquid crystal display (35) or a plurality of light-emitting diodes, or analogue meter means.

Claim 13

An inclinometer according to any of the preceding claims, characterised in that the numerical indicator means (35) includes a plurality of decimal digits, and means for blanking at least one of the digits responsive to non-linearity or over-ranging in the inclinometer.

Claim 14

An inclinometer according to any of the preceding claims, characterised in that it is provided with a reference power source (24) stabilised with respect to temperature.

Claim 15

An inclinometer according to claim 13, characterised in that the power source is provided with Zener diode reference means (8 1 ) for stabilising voltage over approximately 32 0 F to 110°F.

Claim 16

An inclinometer according to any of the preceding claims, characterised in that the power supply means further provides substantially equal output voltages of opposing polarity from a single supply source.

Claim 17

A circuit for an inclinometer providing a numerical readout, characterised in that it comprises a power supply (20) for energising the inclinometer, a source of alternating voltage (21) for driving modulator means (23) which are adapted to provide a peak output substantially constant with respect to temporal and environmental variations of said source, sensor means (27) responsive to the influence of terrestrial gravitational force and to the substantially constant peak voltage, for providing a signal proportional to the inclination of the sensor from the horizontal, means (26) for differentially coupling the substantially constant peak output voltage with respect to ground to energise the sensor, demodulator means (30) synchronised with the source of alternating voltage for detecting the inclination signal, analogue-to-digital convertor means (32) responsive to the detected signal for transforming said signal in analogue form to an equivalent signal in binary digit form, and display driver means (33) coupled to the convertor means and reponsive to the signal in binary digit form for energising digital display means (35), the display means being so contructed and adapted to provide a digital numerical display representing the sense and magnitude of inclination of the sensor from the horizontal.

Claim 18

A circuit for an inclinometer providing a numerical readout, characterised in that it comprises a power supply (20) for energising the inclinometer, a source of alternating voltage (21) for driving modulator means (23) which are adapted to provide a peak output substantially constant with respect to temporal and environmental variations of said source, sensor means (27) responsive to the influence of terrestrial gravitational force and to the substantially constant peak voltage, for providing a signal proportional to the inclination of the sensor from the horizontal, means (26) for differentially coupling the substantially constant peak output voltage with respect to ground to energise the sensor, demodulator means (30) synchronised with the source of alternating voltage for detecting the inclination signal, analogue-to-digital convertor means (32) responsive to the detected signal for transforming said signal in analogue form to an equivalent signal in binary digit form, and display driver means (33) coupled to the convertor means and reponsive to the signal in binary digit form for energising digital display means (35), the display means being so contructed and adapted to provide a digital numerical display representing the sense and magnitude of inclination of the sensor from the horizontal.

Claim 19

A circuit according to claim 16, characterised in that it provides substantially equal output voltages of opposing polarity from a single supply means, comprising voltage divider means (R 1 , R 2 ) having a tie point disposed intermediate the output voltages, operational amplifier means (U 1 ) having differentially disposed inputs, one of the inputs being coupled to said tie point, and one input other than said one coupled to ground, the amplifier having an output also coupled to ground.

Claim 20

A circuit according to claim 17, characterised in that it further comprises passive filter means (C l , C 2 ) coupled to said output voltages.