Since the rotary angular sensor is a main sensor for measuring accurate positions and directions, it plays an important role in various applications such as robot control, cameras and industrial machines.
Generally, the rotary angular sensor can be divided into sensors based on the changes in electric field and magnetic field, and optical sensors according to the underlying physical principle. Electric field-based and magnetic field-based sensors have their own drawbacks respectively.
However, optical sensors operating in visible or infrared light have the advantage of contactless measurements and insensitivity to electromagnetic fields. The sensitivity of an optical sensor might be reduced by external light, but this problem can be solved using a housing and pulsed light. Today, optical angular sensors are indispensable displacement/position sensors for their high resolution, light weight and insensitivity to electromagnetic fields.
Jo Myong Jin, a researcher at the Semiconductor Institute, has proposed a new absolute rotary angular sensor using 1D PSD (position sensitive detector).
Sinusoidal signals with rotation angles are output from the 1D PSD by the sinusoidal path of the optical disc, which allows easy reduction of 1-bit measurement errors present in the binary code disc.
The proposed method is simple in design and the output signal is a combination of an absolute binary code and an analog signal, which can achieve high resolution. In addition, it has the advantage of high linearity and accuracy.