ENCODER

• Main Author: DAIGO AKIHIKO
• Format: Patent
• Language: English
• Published: 20.09.1994
• Edition: 5
• Subjects: ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVEREDIN A SINGLE OTHER SUBCLASS; MEASURING; MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR; PHYSICS; TARIFF METERING APPARATUS; TESTING

PURPOSE:To perform an encoding operation with high resolution and with high accuracy by a method wherein graduations on a scale are formed of marks which give a magneto-optical change to an incident luminous flux and a minimum readout unit size is made fine. CONSTITUTION:A scale part 5 is formed in a concentric shape and in a certain width at the inner side than a radius X from the center of an input shaft (a rotary shaft) 16 in a scale disk 1 formed of a disk-shaped magneto-optical recording medium. When the scale disk 1 is turned relatively to a detector 2 by the input shaft 6, a signal which contains waves corresponding to the number of graduation marks according to a relative rotation angle is output from the detector 2. The signal is amplified, an amplified signal is binary-coded 3, the coded signal is counted and processed by a counting and control circuit 4 and the signal is output as, e.g. an A-phase signal and a B-phase signal. In this case, the magnitude of a minimum readout unit for the graduation marks on the scale part 5 can be formed theoretically to be small down to about 1.1 times the wavelength of detection light. As a result, even when the scale disk 1 is small, the high resolution of the encoder can be obtained.