| 摘要 |
PURPOSE:To obtain a self-clock device which performs a stable synchronizing operation to a phase shift of an input synchronizing signal intrinsic to a magnetic recording and reproducing device, by changing the generating intervals of output pulse signals if input synchronizing signals are not applied consecutively. CONSTITUTION:For instance, a variable preset value generating circuit 14 generates preset values ''8'', ''0'' and ''2'' with the output of a counter 24 set at ''0'', ''1'' and ''2'', respectively. A programmable counter 10 is not preset halfway when no input data pulse is applied. Therefore, the counting action is continued as it is at and after the value preset by a carry signal, and the carry signal is delivered when the content ''F'' is obtained. In this case, the counter 24 is not reset and therefore the contents of the counter 24 are increased as they are up to ''2''. Thus the preset value is set at ''2'', and therefore the time during which the next carry signal emerges is shorter than T. Then the output clock receives a phase shift to the front side. Thus the margin is set at T/2+DELTAT to the phase shift of an input data pulse. This device improves greatly the synchronizing operation to a phase shift. |
