Patent ID: 6172753
Filing Date: 2001-01-09
Classification: G01D

Abstract:
Method of determining with a light beam one of the relative position and the absolute position of a graduation support in relation to a support with an alternating signal, said alternating signal crosses a reference value at least two times, said graduation support and said support being displaceable relative to each other in displacement direction, the method comprising the steps of:producing a light flux by a light source;modifying said light flux by movement of at least one graduation of said graduation support;providing light-sensitive elements on said support;intercepting the modified light flux by said light-sensitive elements; andconverting intensity of the intercepted light flux into an electric signal, wherein:the light flux is modified by said graduation made of at least one series of optical elements, each optical element containing at least one focusing portion;said modified light flux is such that it intercepts at least the entire width of an optical element of said at least one series, said optical element focusing at least one light spot of said light flux onto said support with said light-sensitive elements therein; andsaid light flux intercepted by said focusing part of said optical element is converted into said alternating signal from which said relative position or said absolute position can be determined whereby a maximum value of light energy received by at least one light sensitive element corresponds to one of a maximum electric signal value and a minimum electric signal value of said alternating signal.