| 摘要 |
<p>PURPOSE:To eliminate a shift in display position by switching and using wave front differentiation and wave tail differentiation according to the scanning direction. CONSTITUTION:An input signal V0 is delayed by T1 through the 1st delay circuit 1a and further delayed by T1 through the 2nd delay ciruit 1b. The time T1 corresponds to one step of an angle number. Therefore, the output V1 of the 1st delay circuit and the output V2 of the 2nd delay circuit are as shown by inequalities ( I ), (II), and (III) at the same of a rightward scan, and equations (IV), (V), and (VI) at the time of a leftward scan, where (m) is the angle number and Vs is the control signal of a selector 4. The output V3 of an AND circuit 3 is as shown by (VII) at the same of the leftward scan and (VIII) at the time of the leftward scan. The equation (VII) shows wave front differentiation and the (VIII) shows wave tail differentiation. The end position of the rightward scan and the start position of the leftward scan are only shifted by two on PPI so as to make an angle extraction position coincident between the leftward and rightward scans.</p> |
