Patent ID: 8405821

Claim:
Method for determining a distance to a retroreflective object, the method including the following steps: transmitting a transmitted signal clocked by a clock control from at least one transmitting light source into at least one light path via an object to at least one receiver to detect a change in the transmitted signal from the object, receiving the transmitted signal from the light path by the at least one receiver as a first received signal and converting the first received signal into an electrical signal, transmitting at least one reference signal clocked by the clock control from at least one reference light source into at least one further light path to the at least one receiver, receiving the at least one reference signal from the at least one further light path by the at least one receiver as a second received signal and converting the second received signal into at least one electrical reference signal, evaluating the electrical signal and the at least one electrical reference signal in at least one comparator to determine a distance to the object, comparing one electrical signal integrated over at least a sub-section of the transmitted signal with the at least one electric reference signal, which is adjacent in time to the transmitted signal and integrated over at least one sub-section, generating a control value at an output of the at least one comparator to regulate the amplitude values of at least one of the transmitted signal and the at least one reference signal, wherein an amplitude of the electrical signal and an amplitude of the at least one electrical reference signal are equal in magnitude at least at the inputs of the at least one comparator when in a stabilized state, determining in the stabilized state an amplitude of a clock pulse change signal, occurring during a clock pulse change between at least one of the groups of the first electrical signal and the at least one electrical reference signal or the at least one electrical reference signal and the first electrical signal, the clock pulse change signal corresponding to a light transit time from the at least one transmitting light source to the object and to the at least one receiver, determining the amplitude of the clock pulse change signals in relation to one another or the amplitude of the clock pulse change signal compared to an amplitude independent of the light transit time as a difference value in a further comparator and eliminating or at least minimizing the difference value by means of a regulator, and wherein the at least one electrical reference signal at the input of the at least one comparator is formed by a mean value of the electrical reference signals of at least two reference signals in pulse form, of which one is emitted before and one is emitted after the transmitted signal in pulse form.