This invention relates to an optical source or detector device, and, more particularly, it relates to an optical device having a shape whose light entrance and/or light exit surfaces are adapted to provide desired directional radiating and/or receiving properties.
In video recorders, a photo-cell is typically used to turn off the winding motor promptly when the end of the video tape is reached. For this reason, a section of the video tape at the end of the tape is transparent. Due to this design, the winding motor is turned off by the operation of a photo-cell and also if the video tape should break.
Photo-cells are used also in connection with code disks. In this manner, for example location data can be given with high accuracy.
Radiation of light in, or reception of light from, several spatial directions is necessary in typical arrangement including two or more contactless switches.
Heretofore there was used for each radiation direction or for each reception direction a specially oriented optical light source or respectively a specially oriented optical receiver, so that the total construction for an arrangement with more than one radiating directions or for more than one receiving directions is expensive due to electrical power consumption and is further cost-intensive in terms of installation during manufacture. Also the space requirement becomes a multiple of that which an optical single-direction sensor or an optical single-direction receiver requires.
In the German Patent Document Known as "Offenlegungsschrift" No. 2,733,937 an optical sensor device is described with an envelope whose light entrance and/or light exit surfaces are adapted to provide a desired radiating characteristic. In the installation situation of fixed transmission paths, as they exist, e.g. in television transmission from the antenna box to the T.V. screen or in stereo systems from the control equipment to the loudspeaker boxes, stronger beam focusing is thereby possible between a single optical sender and a single optical receiver. It is thus no longer necessary for the signal source to produce such high outputs in order to reliably transmit light signals. With the same output from the signal source, therefore, a higher signal-to-noise ratio is achieved at the receiving end. Also for the signal receiver the reception characteristic can be adapted in this manner, because any stray light can thereby be eliminated better. However, with such conventional optical components the light beam is able to be focused only between a single optical sender and a single optical receiver.