Optical sensing assembly and encoder utilizing vernier effect and multi-stage position synthesis

An encoder, comprising:

• an optical sensing assembly comprising:
• a scale comprising:
• a first pattern area comprising a plurality of first patterns periodically arranged in a first direction and a second direction;
• and
• a second pattern area comprising a plurality of second patterns periodically arranged in the first direction and the second direction;
• a sensor configured to move relative to the scale in the first direction and comprising:
• a first sensing area configured to sense a change of the first pattern area in the first direction and accordingly generate a first sensing position signal;
• a second sensing area configured to sense a change of the second pattern area in the first direction and accordingly generate a second sensing position signal;
• a third sensing area configured to sense a change of the first pattern area in the second direction and accordingly generate a third sensing position signal;
• and
• a fourth sensing area configured to sense a change of the second pattern area in the second direction and accordingly generate a fourth sensing position signal;
• and
• a signal processing unit connected to the sensor and configured to:
• calculate a first sensing position information, a second sensing position information, a third sensing position information, and a fourth sensing position information respectively from the first sensing position signal, the second sensing position signal, the third sensing position signal, and the fourth sensing position signal;
• generate a first synthesized position information according to the first sensing position information and the second sensing position information;
• generate a second synthesized position information according to the third sensing position information and the first synthesized position information;
• generate a third synthesized position information according to the fourth sensing position information and the first synthesized position information;
• and
• generate a fourth synthesized position information according to the second synthesized position information and the third synthesized position information.