| 摘要 |
PURPOSE:To improve the measuring accuracy of level difference between heads, by measuring the level difference by irradiating momentary light upon the heads in accordance with pulse waves synchronous to the rotation. CONSTITUTION:Changes in magnetism when two magnets 11 pass below a rotary pulse detector 10 are read from the detector 10 and converted into pulse waves. By adjusting a circuit 14 for shifting the phase of the rotary pulse wave, rotations of rotary drums 1 are adjusted so that a strobe lamp 16 can emit light at the moment when a head passes in front of a microscope. The strobe lamp 16 emits light at every one turn of an upper rotary drum 1a and, when an image enlarged by the microscope 3 is photographed by a video camera 5, the head 2 to be observed can be obtained under a state where the head 2 is as if stopped. When the phase is inverted by means of a pulse wave phase shifting circuit 14 in this case, image of another head is obtained. The images 7a and 8a of the two heads are projected by the same monitor television set 6. At the time of the projection the screen of the TV set 6 is divided into two parts, right and left parts, and cursors produced by a picture processing circuit 12 are respectively fitted manually to the images 7a and 8a. Then the difference (a) in the distance between the two cursors is calculated by the circuit 12 and outputted as the head level difference of a rotary head assembly.
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