| 摘要 |
<p>The digital reading tachometer dial esp. for motor vehicles, comprises a circular scale with 200 rev/min increments indicated by light emitting diodes (b). The diodes project through holes in a printed circuit board to which they are electrically connected. The diodes are green since the eye sensitivity is greatest in this part of the spectrum. The pulses from the engine contact breaker are shaped, counted and stored. The contents of the store are decoded and gated by a series of nand-gates, whose outputs drive the LEDs. The display is designed to combine the features of a digital meter with the advantages of a clock type dial for improved visual resolution, taking into account the performance of the human eye.</p> |
