Apparatus for and method of determining distance

Apparatus for determining distance comprising:

• a transmitting unit for emitting a light pulse of a predetermined pulse duration beginning with a leading rising edge and ending with a trailing falling edge, wherein the transmitting unit has a first control input and is adapted to emit a light pulse when a transmission start signal is applied to the first control input,
• a receiver matrix having at least one photoelectric element, wherein the receiver matrix has a measurement output for an output signal and is adapted to output an output signal which is derived from a measurement signal produced by the photoelectric element in dependence on light incident on the photoelectric element, and
• a control unit which is connected to the transmitting unit and the receiver matrix and adapted to produce the transmission start signal and output it to the transmitting unit and to receive the output signal from the receiver matrix and evaluate it,
• characterized in that
• the receiver matrix has a second control input for an integrator control signal and a first and a second integrator which are connected to a single photoelectric element and the second control input, are activatable by the integrator control signal independently of each other and are respectively adapted to integrate the measurement signal over an integration time predetermined by the integrator control signal and thereby to form a respective integrator state and to output the integrator states as an output signal, wherein the control unit has a timer which is adapted to display to the control unit the elapse of a period of time predetermined by the control unit and wherein the control unit is adapted to:
• carry out a measurement cycle with a first activity period of time by delivering two respective integrator control signals firstly to activate the first integrator for a first integration time corresponding to the first activity period of time and after a first elapse of the first activity period of time to deactivate the first integrator and after elapse of a predetermined period of time after deactivation of the first integrator to activate the second integrator, and
• form a distance signal on the basis of the emission of a light pulse and evaluation of the integrator states, to be associated therewith, of the integrators.

A method of determining spacing comprising the steps:

• emitting a light pulse of a predeterminable pulse duration,
• integrating via a first integrator a photoelectric current of a photoelectric element during a first measurement cycle with a first activity period of time, and deactivating said first integrator after a first elapse of the first activity period of time,
• outputting a first output signal,
• integrating via a second integrator the photoelectric current of the same photoelectric element during a second measurement cycle with a second activity period of time which follows the first elapse of the first activity period of time,
• outputting a second output signal, and
• wherein when executing the second measurement cycle allowing a waiting period of time to elapse after the emitting of said light pulse and delivering an integrator control signal for starting the first integrator after the elapse of the waiting period of time, and
• determining a distance of a region-of-interest in relation to the photoelectric current of the photoelectric element during the first measurement cycle and making the waiting period of time less than or equal to a transit time of light over a path corresponding to double the spacing, and
• determining a signal transit time of the light pulse by evaluation of the first and second output signals.

A method of determining spacing comprising the steps:

• emitting a light pulse of a predeterminable pulse duration,
• integrating a photoelectric current of a photoelectric element during a first elapse of a first activity period of time,
• outputting a first output signal,
• integrating the photoelectric current of the same photoelectric element during a second elapse of the first activity period of time which follows the first elapse of the first activity period of time after elapse of a predetermined period of time, wherein the photoelectric current produced by the same photoelectric element during the second elapse of the first activity period of time substantially results from the same emitted light pulse that is emitted during the first elapse of the first activity period of time,
• outputting a second output signal, and
• determining a signal transit time of the light pulse by evaluation of the first and second output signals.