| 摘要 |
<p>A motion detection circuit in a YC separating circuit of PAL signals includes an input terminal for inputting a composite signal; a first memory for delaying the composite signal by 2 lines to produce a 2-line delay output; a second memory for delaying the composite signal by 312 lines to produce a 312-line delay output; a third memory for delaying the 312-line delay output of the second memory by 2 lines to produce a 314-line delay output; a first subtracter for performing subtraction on the basis of the 312-line delay output of the second memory and the 314-line delay output of the third memory to produce a first subtraction signal; a second subtracter for performing subtraction on the basis of the composite signal and the 2-line delay output of the first memory to produce a second subtraction signal; a first band pass filter for band restricting the output of the first subtracter to produce a first band restricted signal; a second band pass filter for band restricting the output of the second subtracter to produce a second band restricted signal; an adder for performing addition on the basis of the output of the first band pass filter and the output of the second band pass filter to produce an added signal; and a comparator circuit for comparing the absolute value of the output of the adder with a previously set threshold value, to output a motion detected signal. In this circuit, the respective differences between two lines in a field and between two lines that are 312 lines away from the first two lines are taken, a carrier color signal is separated from a composite signal, the motion amount of color between the fields is calculated, and from the comparison of the motion amount with a threshold value, a motion detection signal detected from the carrier color signal is obtained. Therefore, as compared with the prior art two frame motion detection, motion detection can be accomplished by a time distance of one-fourth, resulting in improved precision in separation.</p> |
