Electrical telecommunication device e.g. portable telephone detects reflectance signal from reflectance object along detection optical path based on irradiation and determines spacing between reflectance object and projection device

摘要

A projection device (11) projects image information on projection surface located outside of electrical telecommunication device (10). A radiation source (120) performs irradiation to projection surface. A detection device (12) detects reflectance signal (123) from reflectance object (122) along detection optical path (124) based on irradiation to projection surface, to determine spacing between reflectance object and projection device. The detection optical path and projection optical path (111) coincide in region at optical element (112). An independent claim is included for a method for operating electrical telecommunication device.