Patent ID: 6765193
Filing Date: 2004-07-20
Classification: H03K

Abstract:
An apparatus for an optical touch switch being operated by contact, comprising:an optical touch switch having at least one touching surface; a light source for illuminating the optical touch switch and generating an optical beam that senses a mechanical activating force applied on the at least one touching surface of the optical touch switch; a light guide operationally connected to said at least one touching surface such that total internal reflection or light scattering of said optical beam is generated due to application of said mechanical activating force; at least one photodetector for detecting light due to internal reflection or light scattering phenomenon; a plurality of imaging systems for controlling a size of said optical beam and a direction of light propagation for said optical beam; wherein at least one of said plurality of imaging systems is placed between said light source and said at least one photodetector; a plurality of spatial filters for controlling the size of said optical beam and said direction of light propagation and for suppressing unwanted optical noise, wherein at least one of said plurality of spatial filters is positioned adjacent to one of said plurality of imaging systems, another of said plurality of spatial filters is positioned adjacent to said light guide, and said at least one photodetector is positioned adjacent to at least one of said spatial filters; and an electronic control box for sensing changes of an electrical current produced by at least one photodetector and for controlling an electrical load connected at an output of said electronic box, wherein a size, a direction of light propagation and reduction of unwanted optical noise of said optical beam from said light source are controlled by said imaging system, and a size, a direction of light propagation and reduction of unwanted optical noise of said optical beam from said light guide are controlled by said spatial filters.