| 摘要 |
In a method and a device for light propagation time measurement, in particular for cameras, a light signal clocked by a clock controller ( 11 ) is transmitted from at least one transmitter ( 12 ) into a light path ( 14 ) via a retroreflective object (O) to a receiver ( 13 ) for detecting the alteration of the first light signal on account of the approach, presence and/or distance of the object (O). At the receiver, the received signal is determined from the light path on account of the first light signal and, in order to determine the propagation time, is cyclically compared in a comparator ( 15 ) with a second signal which is clocked by the clock controller ( 11 ) and which is produced without the light path ( 14 ), in order to generate a comparison value at the output of the comparator ( 15 ), which value is used for regulating the amplitude values of the transmitted signal and/or of the second signal such that the received signal and the second signal at least at the input of the comparator are substantially identical in magnitude. In parallel, the clock change signal (TW)-occurring during the clock change and corresponding to the light propagation time-between received signal from the light path ( 14 ) and second signal, given the magnitude of received signal from the light path ( 14 ) and second signal corrected to substantially identical magnitude at the input of the comparator ( 15 ), is detected cyclically. A difference value (S 16 ) is determined by comparison of the clock change signals (TW) between received signal and second signal according to their amplitude in a further comparator ( 16 ). The difference value (S 16 ) is altered by means of a phase shifter ( 17 ) for altering the phase delay of the phase of received signal and second signal until the difference value (S 16 ) becomes minimal, preferably zero. The delay of the phase shifter that occurred given a minimal difference value is used for determining the light propagation time. A method for light propagation time measurement which can also operate with more favourable components and lower-frequency amplifiers is created as a result. |
