Tilt compensation apparatus and method for use with a monopod mounted laser range finder apparatus
First Claim
1. A tilt sensor drive circuit for use with a tilt sensor arrangement having two pairs of opposing peripheral electrodes each pair spaced equally apart about a central signal output electrode to provide an output representative of tilt of said sensor arrangement from a horizontal orientation, said circuit comprising:
- four tri-state buffers each having an output connected to one of said peripheral electrodes;
a drive signal generator producing a first and a second drive signal, said first drive signal being connected to an input terminal of one of said tristate buffers in each pair of opposing peripheral electrodes, said second drive signal being connected to an input terminal of another of said tristate buffers for the other electrode of each pair of said opposing peripheral electrodes; and
a channel select signal generator producing a channel select signal connected to the gates of each of said tri-state buffers for one pair of opposing peripheral electrodes and connected through an inverter to the gates of each of said tri-state buffers for the other pair of said opposing electrodes.
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Accused Products
Abstract
A tilt compensation method, circuit and apparatus utilizes a two axis tilt sensor or two single axis tilt sensors for alerting, a user and/or compensating a surveying instrument for off vertical alignment above a reference point when the instrument support is free to move about the reference point, e.g., when mounted on a monopod support. The sensor comprises a cell having a central electrode and four peripheral electrodes spaced 90 degrees apart around the central electrode. Fluid in the cell chamber changes the conductance of the electrodes with reference to the central electrode. The cell is mounted to the support or to the instrument itself. A microprocessor preferably provides a square wave drive signal selectively to alternate pairs of the opposing electrodes through tristate buffers while at the same time the microprocessor provides a channel select signal to the gate of the tristate buffers to float the idle electrodes. The signal on the central electrode is fed to an ADC and then to the microprocessor. The microprocessor preferably produces an alarm signal if the tilt is more than a user determined value. The microprocessor may use the sensed tilt magnitude and direction to automatically calculate corrections and compensate the distance measurement made by the distance measuring device such as a laser range finder for the off vertical orientation of the range finder.
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Citations
26 Claims
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1. A tilt sensor drive circuit for use with a tilt sensor arrangement having two pairs of opposing peripheral electrodes each pair spaced equally apart about a central signal output electrode to provide an output representative of tilt of said sensor arrangement from a horizontal orientation, said circuit comprising:
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four tri-state buffers each having an output connected to one of said peripheral electrodes; a drive signal generator producing a first and a second drive signal, said first drive signal being connected to an input terminal of one of said tristate buffers in each pair of opposing peripheral electrodes, said second drive signal being connected to an input terminal of another of said tristate buffers for the other electrode of each pair of said opposing peripheral electrodes; and a channel select signal generator producing a channel select signal connected to the gates of each of said tri-state buffers for one pair of opposing peripheral electrodes and connected through an inverter to the gates of each of said tri-state buffers for the other pair of said opposing electrodes. - View Dependent Claims (2, 3, 4, 5)
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6. A tilt alarm apparatus for indicating when a member exceeds a predetermined tilt variance from a vertical orientation comprising:
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a housing fastened to said member; a power supply in said housing; a two axis electrolytic tilt sensor mounted in said housing having a central output electrode and two pairs of opposing peripheral electrodes equally spaced about said central electrode; and a signal generator in said housing connected to said power supply and to said sensor, said generator producing drive signals and an alarm signal upon receipt of a tilt signal above a threshold; a sensor drive circuit connected to said signal generator, said circuit selectively driving each of said pairs of peripheral electrodes to produce said tilt signal; and an alarm circuit connected to said generator producing an audible alarm upon receipt of said alarm signal. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A tilt alarm module adapted to be fastened to a monopod support for a distance measuring instrument in which the alarm module senses and indicates when the monopod support exceeds a predetermined inclination angle from a vertical orientation, said module comprising:
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a housing fastened to said monopod support; a power supply in said housing, a two axis electrolytic tilt sensor mounted in said housing having a central signal electrode aligned parallel to said monopod support and two pairs of opposing peripheral electrodes equally spaced about said central electrode; a microprocessor in said housing connected to said power supply, said microprocessor producing a first and a second drive signal connected to said peripheral electrodes and producing a channel select signal for selecting between said opposing pairs of electrodes, said microprocessor further including a tilt input connected to said central signal output electrode and an alarm output providing an alarm signal when said tilt input from said tilt sensor exceeds a predetermined value. - View Dependent Claims (14, 15)
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16. A laser based surveying instrument comprising:
a distance measuring modules a compass module; and
a power supply module mounted on a monopod support, wherein said compass module includes a two axis electrolytic tilt sensor fastened to said compass module, said tilt sensor having a central signal electrode oriented parallel to an axis of said monopod support and two pairs of opposing peripheral electrodes equally spaced about said central electrode, said compass module including a drive circuit for said tilt sensor and an alarm circuit for providing an alarm when said monopod support is tilted beyond a predetermined threshold tilt value from vertical.- View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. A method for alerting a surveying instrument operator to approaching unacceptable off vertical alignment conditions of the instrument when the instrument is mounted on a one dimensional support comprising the steps of:
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a) providing a surveying instrument mounted on a one dimensional support; b) providing a tilt sensor on the support capable of sensing a degree of tilt of the support from a vertical orientation; c) sensing the degree of tilt; and d) communicating the degree of tilt to the operator. - View Dependent Claims (24, 25, 26)
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Specification