Apparatus for determining distance

Claim 2

In an apparatus for determining distance, said apparatus comprising means for transmitting successive pulses of energy, means for receiving said pulses when reflected from an object, means for continuously ascertaining the time duration between the transmission of said pulses and the reception of the corresponding reflections to produce an electrical analogue signal indicative of the distance between the apparatus and said object, and means for producing a warning signal when said electrical analogue signal reaches a predetermined value; the improvement comprising means for producing a prediction signal indicative of a predetermined distance being reached within a predetermined time interval by continuously assessing the rate of change of said electrical analogue signal.

Claim 3

An apparatus according to claim 1, wherein there is further provided means for varying the repetition rate of said transmitted pulses in accordance with pre-selectable ranges of distance and an instrument for indicating said electrical signal.

Claim 4

An apparatus according to claim 2, wherein a monostable device is provided to cause the indicating instrument to indicate the distance between the object and a point displaced from a transducer head serving to transmit and receive said pulses and to selectively inhibit the operation of said receiving means during the transmission of pulses, and wherein the monostable device produces a square-wave pulse of pre-set duration upon transmission of each of said pulses.

Claim 5

An apparatus according to claim 3, wherein the receiving means produces square-wave pulses indicative of echo reflection pulses and the means for ascertaining the said time duration at least includes a bi-stable device adapted to produce an output pulse triggered by the lagging edge of each pulse produced by said monostable device and re-set by the leading edge of a succeeding echo reflecting pulse produced by the receiving means and corresponding to said pulse produced by the monostable device.

Claim 6

An apparatus according to claim 3 and further comprising means for producing masking pulses each of which prevents indicative operation of the apparatus during its duration.

Claim 7

An apparatus according to claim 1 and further comprising means for producing masking pulses each of which prevents indicative operation of the apparatus during its duration.

Claim 8

An apparatus according to claim 5, wherein there is provided means for producing an inspection pulse the duration of which is equal to the duration between the lagging edge of one of said masking pulses and the lagging edge of the corresponding output pulse from said bi-stable device and wherein there is also providEd means for determining the duration of each inspection pulse.

Claim 9

An apparatus according to claim 7, wherein the means for determining the duration of each inspection pulse is a ramp voltage generator, and a feed back loop extends between the ramp generator and said masking-pulse producing means, the feed back loop serving to apply a control voltage to said masking-pulse producing means.

Claim 10

An apparatus according to claim 8, wherein the ramp generator is connected to a sample and hold circuit adapted to store the maximum value of the output voltage of said ramp generator and there is provided means for producing a sample pulse the duration of which is equal to the duration between the lagging edge of the corresponding output pulse of said bi-stable device and the leading edge of the succeeding pulse from said monostable device, the sample pulse being produced only when the bistable device is reset by an echo reflection pulse and being conveyed to the sample and hold circuit to cause the latter to deliver the voltage stored thereby.

Claim 11

An apparatus according to claim 9, wherein the output from the sample and hold circuit produces said control voltage and a delay circuit is connected between said control voltage input of the masking-pulse producing means and the output of the bistable device, said delay circuit being selectively operable to short circuit the control voltage if several echo reflection pulses become blocked by said masking pulses.

Claim 12

An apparatus according to claim 1, wherein there is provided a potentiometer for setting a voltage corresponding to the value of said analogue voltage which would be indicative of a certain distance, and means for producing a warning signal includes a comparator adapted to indicate equivalence between the analogue voltage and the voltage set by said potentiometer.

Claim 13

An apparatus according to claim 1, wherein the means for producing a prediction signal is in the form of a computing device for continuously computing an estimated time before collision with the object from the rate of change of said electrical analogue signal and means for comparing the output from said device with a manually preselected time interval representing the time of warning desired.

Claim 14

An apparatus according to claim 12, wherein said computing device includes a differentiating circuit.

Claim 15

In an apparatus for determining distance, said apparatus comprising means for transmitting successive pulses of energy, means for receiving said pulses when reflected from an object, means for continuously ascertaining the time duration between the transmission of said pulses and the reception of the corresponding reflections to produce an electrical analogue signal indicative of the distance between the apparatus and said object, and means for producing a warning signal when said electrical analogue signal reaches a pre-determined value; the improvement comprising means for producing a prediction signal by continuously assessing the rate of change of said electrical analogue signal, said prediction signal being indicative of a predetermined distance being reached within a predetermined time interval, and means for eliminating spurious echo reflections and for correcting for temporary loss of reflection pulses.

Claim 16

In an apparatus for determining distance, said apparatus comprising means for transmitting successive pulses of energy, means for receiving said pulses when reflected from an object, means for continuously ascertaining the time duration between the transmission of said pulses and the reception of the corresponding reflections to produce an electrical analogue signal indicative of the distance between the apparatus and said object, and means for producing a warning signal when said electrical analogue signal reaches a pre-determined value; the improvement comprising means for producing a prediction signal by continuously assessing the rate of change of said electrical analogue signal, said prediction signal being indicative of a predetermined distance being reached within a predetermined time interval, and means for eliminating spurious echo reflections and for correcting for temporary loss of reflection pulses.