| 摘要 |
PURPOSE:To elevate an information signal as PCM to that of high density, high quality and high S/N, by making the sum of a bias magnetic field and a fixed amount of signal magnetic field larger than the magnetic force of the recording medium. CONSTITUTION:A ring electromagnet 1 magnetizes in saturation a magnetic tape 1 to 1 polarity uniformly in the direction of thickness, when the magnetic poles 13a and 13b are N pole and S pole, respectively, the magnetic layer 1a of the tape 1 is magnetized in the direction of thickness, and its surface becomes N pole. Moreover, a bias coil 12 is arranged around the recording coil 11, and each coil of 11 and 12 is opposite to each other on the surface of the magnetic layer 1a. And a regular DC current always flows into the coil 12, and a pulse current is supplied to the coil 11 in accordance with the information signal. Each current value of the coils 11 and 12 is selected so that the sum Hb+Hsg of the bias magnetic field Hb provided to the magnetic layer 1a and a fixed amount of signal magnetic field Hsg can be larger than the magnetic force Hc of the magnetic layer 1a. And the information recording part becomes S pole, and a magnetic wall 15 is formed between S pole and N pole. |
