A 3.2 kHz, 13-bit Optical Absolute Rotary Encoder with a CMOS Profile Sensor

We have developed a 3.2 kHz, 13-bit optical absolute rotary encoder system using a profile sensor and a slit disc. The profile sensor, which we have designed for this purpose, is a unique CMOS area image sensor aimed at highspeed position detection of X and Y-axes. The profile data of Y-axis from the profile sensor is used for recognition of an index code number of a slit disc and that of X-axis is used for position detection of the index code. This combination of both axes information enables to achieve high resolution even with less number of index codes (64 indexes) and small amount of digital calculations. Experimental results assure that this system can detect 13 bit angle resolution (0.044 degree) and the speed of detection reaches at maximum 3.2 kHz.