Rotation angle detection apparatus

A rotation angle detection apparatus for detecting a rotation angle of an object, the rotation angle detection apparatus comprising:

• an incremental rotary scale configured to rotate together with the object, the rotary scale including both a detection region and a non-detection region, the detection region being provided along a circumferential direction of the rotary scale and having a scale formed therein for detecting the rotation angle of the object, the non-detection region adjoining the detection region in the circumferential direction and having no scale formed therein;
• and
• a detector configured to generate an electrical signal based on an input signal and detect the rotation angle of the object based on the electrical signal, the input signal indicating change in position of the scale of the detection region, the position of the scale of the detection region changing according to change in the rotation angle of the object, the electrical signal periodically changing according to the change in the position of the scale of the detection region,
• wherein
• the rotary scale has no scale dedicated for detection of a reference angle for the rotation angle of the object, and
• the detector is further configured to detect the reference angle by counting the number of positional changes from an end of the scale of the detection region of the rotary scale, the positional changes being indicated by the input signal.