Dynamic control arrangement for a distance measuring apparatus
First Claim
1. Distance measuring apparatus for measuring the transit times of individual unmodulated measuring light pulses to a target and therefrom, by reflection, back to the apparatus and of individual unmodulated reference light pulses propagated inside the apparatus which for these purposes comprises:
- a transmitter driven by a trigger signal from a trigger generator for emitting individual unmodulated light pulses of short duration,a first light path from the transmitter to a light path change-over switch,a second light path from the change-over switch to an optical transmitting means for transmitting individual measuring light pulses toward said target,an optical receiving means for receiving individual reflected unmodulated measuring light pulses from said target,a third light path from said optical receiving means to an electro-optical receiver for supplying to said receiver individual reflected measuring light pulses,a reference light path from said change-over switch to said electro-optical receiver, said reference light path establishing predetermined transmit times for reference light pulses,a control means for controlling said light path change-over switch to direct light pulses from said first light path alternately into said second light path for use as measuring light pulses or into said reference light path for use as reference light pulses,a time measuring means for transmit time measurements of individual light pulses which measurement is initiated by a start signal related to the trigger signal from the trigger generator, said time measuring means also being operatively connected to said electro-optical receiver for receiving therefrom a stop signal on receipt of individual unmodulated light pulses for terminating said transit time measurement of said individual light pulse,a storage and computing means for storing transmit time measurement values and subtracting transit time measurement values of individual reference light pulses from transit time measurement values of corresponding individual measuring light pulses,dynamic damping means for attenuatng an optical light pulse travelling within a relevant light path, said dynamic damping means comprising a movable attenuator element providing different attenuation values determined by the position thereof in said relevant light path and means for monitoring the movement of said attenuator element, said monitoring means being operatively connected to a control means for controlling the trigger generator to produce its trigger signals in timed relation to the movement of said attenuator element.
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Accused Products
Abstract
The invention provides a distance measuring apparatus for determining the distance of a target object as a function of the transit time of a measurement light pulse which is emitted by a transmitter in the transmission portion of the apparatus towards the target object, reflected thereby and received by the receiving portion of the measuring apparatus and for attainment of superior measurement accuracy the intensity of the measurement light pulse is correlated to the distance and reflectivity of the target object as well as to the "transparency" of the transmission medium between the measuring apparatus and the target object, such correlation being effected by optical damping of either the transmitted light pulses and/or the reference light pulse and/or the light pulses reflected by the target. Optical damping may advantageously be effected by means of a light path change-over switch which feeds a light pulse, generated by the transmitter by controlling the timing of a trigger generator for the transmitter, so that the full intensity or attenuated optic light is passed either into a transmitting measurement light path or into a reference light path having a known transit time for the reference light therein, electrical delays inherent in the apparatus and causing errors in distance measurement being compensated for by subtracting the transit time measurement values of reference light pulses from transit time measurement values of transmitted measurement light pulses.
91 Citations
27 Claims
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1. Distance measuring apparatus for measuring the transit times of individual unmodulated measuring light pulses to a target and therefrom, by reflection, back to the apparatus and of individual unmodulated reference light pulses propagated inside the apparatus which for these purposes comprises:
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a transmitter driven by a trigger signal from a trigger generator for emitting individual unmodulated light pulses of short duration, a first light path from the transmitter to a light path change-over switch, a second light path from the change-over switch to an optical transmitting means for transmitting individual measuring light pulses toward said target, an optical receiving means for receiving individual reflected unmodulated measuring light pulses from said target, a third light path from said optical receiving means to an electro-optical receiver for supplying to said receiver individual reflected measuring light pulses, a reference light path from said change-over switch to said electro-optical receiver, said reference light path establishing predetermined transmit times for reference light pulses, a control means for controlling said light path change-over switch to direct light pulses from said first light path alternately into said second light path for use as measuring light pulses or into said reference light path for use as reference light pulses, a time measuring means for transmit time measurements of individual light pulses which measurement is initiated by a start signal related to the trigger signal from the trigger generator, said time measuring means also being operatively connected to said electro-optical receiver for receiving therefrom a stop signal on receipt of individual unmodulated light pulses for terminating said transit time measurement of said individual light pulse, a storage and computing means for storing transmit time measurement values and subtracting transit time measurement values of individual reference light pulses from transit time measurement values of corresponding individual measuring light pulses, dynamic damping means for attenuatng an optical light pulse travelling within a relevant light path, said dynamic damping means comprising a movable attenuator element providing different attenuation values determined by the position thereof in said relevant light path and means for monitoring the movement of said attenuator element, said monitoring means being operatively connected to a control means for controlling the trigger generator to produce its trigger signals in timed relation to the movement of said attenuator element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. Distance measuring apparatus for measuring the transit time of an individual unmodulated measuring light pulse to a target and therefrom, by reflection, back to the apparatus which for this purpose comprises a transmitter driven by a trigger signal from a trigger generator for emitting individual unmodulated measuring light pulses of short duration, an optical receiving means including an electro-optical receiver and a time measuring means for transit time measurement of an individual measurement light pulse, which measurement is initiated by a start signal related to the trigger signal from the trigger generator, said time measuring means also being operatively connected to said electro-optical receiver for receiving therefrom a stop signal on receipt of an individual reflected unmodulated measuring light pulse by the receiver for stopping said transit time measurement of said individual measuring light pulse, a first light path from the transmitter to an optical transmitting means for transmitting individual light pulses toward said target, a second light path from said receiver to an optical receiving means for supplying to said receiver individual reflected measuring light pulses received by said optical receiving means from the target, a reference light path between the first and second light paths and communicating therewith, said reference light path establishing predetermined transit times for a reference light pulse, a light path change-over switch communicating with the first and reference light paths for supply of a transmitted pulse to said optical transmitting means and to said reference light path, said trigger signal from said trigger generator being timed in relation to said light path change-over switch for sequentially directing light pulses into said first light path and said reference light path, said light path change-over switch comprising a rotating disc having a rotational axis parallel to the first light path and being provided with at least one opening for passing therethrough said transmitted light to said first path and further provided with at least one mirror for deflecting the transmitted light through a predetermined angle into the reference light path.
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27. Distance measuring apparatus for measuring the transit times of individual unmodulated measuring light pulses to a target and therefrom, by reflection, back to the apparatus and of individual unmodulated reference light pulses propogated inside the apparatus which for these purposes comprises:
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a transmitter driven by a trigger signal from a trigger generator for emitting individual unmodulated light pulses of short duration, a first light path from the transmitter to a light path change-over switch, a second light path from the change-over switch to an optical transmitting means for transmitting individual measuring light pulses toward said target, an optical receivng means for receiving individual reflected unmodulated measuring light pulses from said target, a third light path from said optical receiving means to an electro-optical receiver for supplying to said receiver individual reflected measuring light pulses, a reference path from said change-over switch to said electro-optical receiver, said reference light path establishing predetermined transit times for reference light pulses, a control means for controlling said light path change-over switch to direct light pulses from said first light path alternately into said second light path in order to use them as measuring light pulses or into said reference light path in order to use them as reference light pulses, a time measuring means for transit time measurements of individual light pulses which measurement is initiated by a start signal related to the trigger signal from the trigger generator, said time measuring means also being operatively connected to said electro-optical receiver for receiving therefrom a stop signal on receipt of the respective individual unmodulated light pulse for stopping said transit time measurement of said individual light pulse, a storage and computing means for storing transit time measurement values and subtracting transit time measurement values of individual reference light pulses from transit time measurement values of individual measuring light pulses, and means for monitoring the movement of said light path change-over switch, said monitoring means being operatively connected to a control means controlling the trigger generator to produce its trigger signals in timed relation to the movement of said light path change-over switch for sequentially directing light pulses into said second light path and said reference light path, said light path change-over switch comprising a rotating disc having a rotational axis parallel to the second light path and being provided with at least one opening for passing therethrough said transmitted light to said second path and being provided with at least one mirror for deflecting the transmitted light through a predetermined angle into the reference light path.
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Specification