| 摘要 |
PURPOSE:To obtain a rotary encoder generating no phase error caused by the eccentricity of a code plate during assembling and the shift in the attachment position of a detection element, by arranging four detection elements toward the radius direction of the code plate so as to provide proper intervals. CONSTITUTION:Four detection elements a1, a2, b1, b2 are arranged toward the radius direction of a code plate 1 at proper intervals la1, la2, lb1, lb2 in an up- and-down position. In this case, in order to obtain signals of which the phases are different 90 deg. and strong signals, a mask shown by A is applied while the detection elements arranged as shown by B are superposed on said mask to be used and property such that, when two AC signals having equal amplitude are synthesized, a signal having the average phase of both of them can be obtained is utilized. The dimensions of said elements are determined so that the signal obtained by synthesizing the signals of the detection elements a1, a2 and the signal obtained by synthesizing the signals of the detection elements b1, b2 are detected almost at the center S of the detection element group to eliminate the phase error caused by the eccentricity of the code plate. By this method, a rotary encoder generating no phase error by the shift of the element attaching position can be obtained. |
