Digital compass
First Claim
1. In a digital compass, encoding means for converting compass readings into a numerical display corresponding to the directional displacement of said compass, comprising:
- a rotatable disc including means orienting a radius of said disc in alignment with the earth'"'"'s magnetic field, said disc having a reference position index and a digit code strip divided into equally spaced increments representing degrees of angular displacement away from said reference position index,a sensing unit operative to generate a combination of signals and including a reference position sensor operative to generate a signal in response to alignment of said reference position sensor with respect to said reference position index so as to define a reference position, said combination of signals representing the direction and number of increments of movement of said code strip away from said reference position,decoding means including counting means operative in response to the combination of signals generated by said sensor unit to count up or down in accordance with the direction and number of increments of movement of said digit code strip, andreference position control means responsive to receipt of a reference position signal to clear said counting means.
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Accused Products
Abstract
A hand-held digital compass employs an incremental encoder including a digit code disc and sensor unit which are so interrelated with a logic circuit as to permit automatic referencing of the compass when power is initially applied; and further permits use of an extremely small digit code disc which in cooperation with the sensor unit will permit digital recording of the direction and degree or extent of displacement of the compass in a given direction. The logic circuit employed is self-correcting for errors caused by input line noise and permits utilization of a simplified counting circuit for reading and digitally displaying degrees of movement between zero and 360°.
33 Citations
16 Claims
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1. In a digital compass, encoding means for converting compass readings into a numerical display corresponding to the directional displacement of said compass, comprising:
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a rotatable disc including means orienting a radius of said disc in alignment with the earth'"'"'s magnetic field, said disc having a reference position index and a digit code strip divided into equally spaced increments representing degrees of angular displacement away from said reference position index, a sensing unit operative to generate a combination of signals and including a reference position sensor operative to generate a signal in response to alignment of said reference position sensor with respect to said reference position index so as to define a reference position, said combination of signals representing the direction and number of increments of movement of said code strip away from said reference position, decoding means including counting means operative in response to the combination of signals generated by said sensor unit to count up or down in accordance with the direction and number of increments of movement of said digit code strip, and reference position control means responsive to receipt of a reference position signal to clear said counting means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A digital compass comprising in combination:
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a circular scale having magnetic means adapted to orient said scale in alignment with the earth'"'"'s magnetic field and a code strip thereon comprising alternate light transparent and opaque sections divided into equally spaced increments on said scale, a sensing member including first and second light sensing means aligned with said code strip and spaced an odd number of increments apart with respect to said code strip whereby to generate signals in out-of-phase relation to one another in response to movement of said alternate light transparent and opaque sections across said light sensing means, and reference position sensing means for generating a signal in response to alignment of said code strip with a predetermined reference position, decoder means for generating a combination of signals for each signal generated by said first and second light sensing means, means ANDing the combination of signals generated by said decoding means with the signal received from said reference position sensing means, means for storing each combination of signals received from said decoding means for comparison with each next combination of signals and to generate an output pulse representing the direction of movement of said scale based on a comparison of each successive combination of signals generated, and counting means adapted to numerically count up or down in accordance with the output pulse received from said comparison means. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A digital compass comprising in combination:
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a rotatable circular scale having magnetic means adapted to orient said scale in alignment with the earth'"'"'s magnetic field, a first digit code strip thereon comprising alternate light transparent and opaque sections divided into equally spaced degree increments on said scale from 0°
to 360°
, and a second code strip spaced radially of said first code strip having a transparent reference position thereon,a sensing member including first and second light sensing means aligned with said first code strip and spaced an odd number of increments apart with respect to said code strip whereby to generate signals in out-of-phase relation with one another in response to movement of said alternate light transparent and opaque sections across said light sensing means, and reference position light sensing means aligned with said second code strip for generating a reference signal in response to alignment with the transparent reference position, decoder means for generating a combination of signals for each signal generated by said first and second light sensing means, means ANDing the combination of signals generated by said decoding means when a signal is received from said reference position sensing means, means for storing each combination of signals received from said decoding means for comparison with each next combination of signals and to generate an output pulse representing the direction of movement of said scale based on a comparison of each successive combination of signals generated, counting means adapted to numerically count up or down in accordance with the output pulse received from said comparison means, and first logic means for clearing said counting means to zero in response to said reference signal, and second logic means for advancing said counting means to "359" when said scale is rotated one increment from 0°
to 359°
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Specification