PURPOSE: To output pieces of information on a speed and a direction at the same time without increasing the number of outputs by varying the pulse width of output pulses of the speed detector and multiplexing the direction information with the speed information.
CONSTITUTION: When a disk 1 rotates forward at a constant speed, slits of the disk 1 crosses a photointerrupter 4, which sends its output signal 2 to a microcomputer 5. The current waveform of the signal 2 is an output signal waveform 6 in the constant-speed forward rotation, the pulse width of a high- level signal corresponding to slit width varies in the order of W1, W2, W3, W4, W1, W2..., and the pulse width ratio is 1:2:3:4. Further, when the disk 1 reverses at the constant speed, the signal 2 has an output waveform 7 in constant-speed reversing and the width of the pulse signal varies in the reverse order of the forward rotation. For the purpose, the order of variation in the width of the signal pulses is analyzed to decide the rotating direction. When the rotating speed is detected, a microcomputer 5 measures the period T of the edge of the signal 2 corresponding to the rotating direction to detect the speed of the disk 1.
KANEKO ATSUSHI
NAKAJIMA AKIO
IKOMA JUNICHI
HITACHI VIDEO ENG
| JPH0212619B2 | 1990-03-22 | |||
| JPS60131470A | 1985-07-13 | |||
| JPS61173165A | 1986-08-04 |
| WO1990006517A1 | 1990-06-14 |