Optical distance sensor with closed-loop exposure control and corresponding method

An optical distance sensor with a closed-loop exposure control, the optical distance sensor comprising:

• a light source for generating an illumination light beam and for guiding the illumination light beam to a measured object,
• a detector for detecting a measuring light beam that has been caused by reflection of the illumination light beam at the measured object,
• a measurement controller for controlling the detector when the measuring light beam is detected and when measurement values are read out,
• an evaluation unit configured, in a phase of a measurement operation, to evaluate measurement values of the detector for determining a distance between the optical distance sensor and the measured object, and
• a closed-loop controller which drives the light source, the detector, and/or the measurement controller such that a received amount of light, which is detected during a shutter time by the detector or a portion of the detector, is in a target range or approaches the target range,
• wherein the optical distance sensor is configured, both in phases of the measurement operation and in measurement pauses between the phases of the measurement operation, to emit an illumination light beam, and to detect a measuring light beam, and to evaluate the measuring light beam by the closed-loop controller,
• wherein at least one intermediate measurement is carried out by the optical distance sensor between two successive phases of the measurement operation, wherein the illumination light beam is generated during an intermediate measurement, and the measuring light beam is detected by the detector without a distance value being determined,
• wherein the measurement values of the detector that are read during an intermediate measurement are evaluated only for control of the received amount of light and are not used to determine a distance value, and
• wherein, in a case of a plurality of intermediate measurements, before performing a possible intermediate measurement, the optical distance sensor is configured to check whether a closed-loop control difference determined by the closed-loop controller is above a first threshold value and a further intermediate measurement is thus required, or whether the closed-loop control difference determined by the closed-loop controller is below a second threshold value and a further intermediate measurement is thus unnecessary.