| 摘要 |
A line scale scanner utilizing three photoelectric cells, offset relative to one another within a space no larger than one divisional unit of the scale, to be operated as the scale moves to divide each scale unit into six increments. Each of the six increments can be obtained as the line scale moves forward or backward, providing 12 combinations from which a discriminator forms electric pulses. The pulses indicate if the increment is odd or even and if it occurred as the line scale moved forward or backward. The odd and even pulses which are provided on two different outputs of the discriminator can then be fed to counters which analyze them to determine if a system malfunction has occurred. The counters can be connected to provide the same output when the system is operating without error. Likewise, the counters can be connected to count complementary when no error has occurred. A circuit is also disclosed which provides a defect signal when a malfunction of the system occurs. |
