PURPOSE: To improve the S/N as well as the frequency characteristics over a wide range by detecting the magnetic variation of a backing layer of high permeability by means of a coil connected magnetically to said magnetic variation.
CONSTITUTION: A detection coil 10, for example, which is largely wound around a thin film magnetic material 5 is used to detect the magnetic variation of a magnetized area 9 within a backing layer 3 having high permeability to secure an effective connection. A high frequency magnetic field is produced from the coil 10 in the direction vertical to the surface of a recording medium 1, and the area 9 produces the ferromagnetic resonance. Therefore the tuning frequency and Q are varied large in response to the state of magnetization of the area 9 for a tuning circuit consisting of the coil 10 and a tuning capacitor 11. Accordingly the resonance output voltage of the tuning circuit also has a big change. Thus, the S/N is improved as well as the frequency characteristics over a wide range.
CHIBA OSAMU
SAWAZAKI KENICHI
YATABE SHIGERU
| JPS57123504A | 1982-08-02 | |||
| JPS5848203A | 1983-03-22 | |||
| JPS58122601A | 1983-07-21 | |||
| JPS5744212A | 1982-03-12 |