| 摘要 |
<p>In a fruit machine, means sensing the positions in which symbol carriers (R) stop can accommodate rotation of the carrier in either direction. Associated with each carrier, two photo-electric cells (P1, P2) are each arranged to receive pulses of light from a light source through one of two series of apertures (S) in a disc (D) which rotates with the carrier (R). The apertures are formed so that the cells (P1, P2) generate two trains of electrical pulses of the same frequency but out of synchronism. The pulses are fed as an activating signal to a counter which changes its state in step with rotation of the carrier. Since the trains are out of synchronism, the signal is assymetrical in time so that reversal of the rotation of the carrier causes a different signal to be sent to the counter. The two signals cause adjustment of the counter by an increment and a decrement, respectively.</p> |
