Reflective light barrier for surface servo-sensor - has receive phototransistor with direct light source for additional receiver irradiation

摘要

The reflected light barrier recognises a portion of a reflected light for derivation of a corresponding signal. It is used for the control of covering a surface, or a space, by an infra-red radiation transmitter. A phototransistor is used as receiver (2) and contains a light source (19). The radiation of this source is directed from a transmitter (1) continuously onto the phototransistor (11), in addition to a reflected portion of a modulated light radiation. In this manner, amplification by the receiver phototransistor can be obtained, which may be continuously held within given limits. The light source is arranged in a common housing with the phototransistor such that the light detecting surface of the transistor is continuously engaged by light radiation, due to fixed mounting of the light source.