| 摘要 |
A n-key capacitive keyboard is coupled to an n-bit shift register. Each key is sequentially "interrogated" and, if actuated, an output pulse appears which is applied to the input of the shift register. The output pulse is also compared to the output of the shift register, corresponding to the "state" of the key in the prior cycle. An output pulse is generated on the first occurrence of a signal representing actuation of the key. The output of the shift register is also applied to make the key circuit more sensitive and therefore require less key travel to pass the interrogating pulse.
|
