| 摘要 |
<p>PURPOSE:To make the title reader inexpensive by applying phase inversion detection and maximum waveform amplitude detection to a voltage induced in a cursor so as to detect a coordinate of the cursor for reading the coordinate thereby eliminating the need for a cursor height correction means and a time measuring means. CONSTITUTION:An X coordinate detection conductor loop is formed by reflecting alternately electric conductor wires 1, 2 respectively in the same pitch P/2 and arranging them in parallel so as to form a deviation corresponding to P/4 between the conductor wires 1 and 2. In applying a sinusoidal wave between terminals (a, b) and a cosine wave between terminals (c, d) to excite the reader, an induced voltage Eef expressed in equation I is induced between terminals of the cursor 3, where A is a coupling coefficient between the loop and cursor, (x) is a distance from the center to the leftmost and of the cursor 3 and (alpha) is a variable. In increasing/decreasing the (alpha), the relation of voltage Eef=0 is attained with x-alpha=nP and the phase is inverted from this time. In taking the (alpha) in this case as alphax, the coordinate x(=alphax+nP) is calculated by detecting (n) decided depending on the said alphax and at which period the cursor exists. The coordinate (y) is obtained similarly.</p> |
