Device for measuring angular position and speed, in particular for electric motors

摘要

The invention relates to a device for measuring angular position and speed, in particular for small electric motors, containing a light source (7) and a mirror (2) which is arranged on the motor shaft (1) and reflects the light beams from the light source (7) at an angle of 90@, and a stationary optical modulator at the level of the mirror, which is arranged coaxially in the device and is connected via an optical system to a counting circuit (9) for the electrical pulses. According to the invention, the optical modulator is formed by the side wall, exhibiting an incremental pattern (5), of a rotationally symmetrical body (3) whose inner wall reflects the light. The mirror (2) is the first element of the optical system (2, 6, 11, 8), which feeds the light reflected by the optical modulator to a photodetector (8) of the counting circuit (9) of the electric pulses. In accordance with the invention, the photodetector (8) consists of three photoelements (14, 15, 16) in the arrangement of an equilateral triangle. Half the diameter of the active surface of each photoelement (14, 15, 16) is smaller than the width A of the image (17) of the marking (4) of the incremental pattern in the region of the photodetector (8). The width of a marking (4) of the incremental pattern (5) is not permitted to be greater than the width of the zone between the markings (4). <IMAGE>