| 摘要 |
PURPOSE:To detect the position of a video head with high accuracy, by detecting a head gap line and its upper and lower contours from the image of a video head, calculating the position coordinates of the intersection of both contours and then delivering the coordinates of the middle point of above-mentioned position coordinates as a position signal of the video head. CONSTITUTION:A video head 2 is set in the direction of a scanning line of an image pickup device 8, and an obscure binary coded picture is obtained by the device 8, a contour emphasizing circuit 12 and a binary coding circuit 13 respectively. This binary coded image is stored in a memory 14, and a counter circuit 15 counts the number of white dots corresponding to white level signals opposite to a video head surface 20. Then a claculator 17 calculates the position of the head 2 in its mutual height direction, and the information signal and the head reference value signal are calculated. Thus a counting region 26 including a head gap line 21 is set on the memory 14. The focusing is performed with a signal based on the line 21. The middle coordinates are calculated at the intersections between the line 21 and upper and lower contour lines and then delivered via an interface 18. With this output, the position of the head 2 is detected with high accuracy. |
