| 摘要 |
A signal processing circuit (11) calculates the intensity ratio (Ra) of light from light-emitting elements (3, 4) that has been reflected and converts the reflected light intensity ratio (Ra) to an inclination angle (&thetas;1) of an object under detection (Obj) using a table (T1). The signal processing circuit (11) calculates the intensity ratio (Rb) of light from light-emitting elements (4, 5) that has been reflected and converts the reflected light intensity ratio (Rb) to an inclination angle (&thetas;2) of the object under detection (Obj) using a table (T2). The signal processing circuit (11) calculates the intensity ratio (Rc) of light from light-emitting elements (5, 3) that has been reflected and converts the reflected light intensity ratio (Rc) to an inclination angle (&thetas;3) of the object under detection (Obj) using a table (T3). The signal processing circuit (11) determines the inclination of the object under detection (Obj) on the basis of the inclination angles (&thetas;1 to &thetas;3). |
