| 摘要 |
PURPOSE:To extend the recording band up to a region of the upper band wave of a luminance signal having a modulated frequency and to record the upper band wave with a satisfactory level, by connecting a series circuit of a damping resistance and a coil in parallel to the primary coil of a rotary transformer. CONSTITUTION:A series circuit of a damping resistance R1 and a coil L is connected in parallel to the primary coil of a rotary transformer 30. In this example a resistance R2 is used as shown in the diagram. A capacity Cs is formed in parallel to the primary coil. An equivalent circuit is formed as shown in the diagram by setting the inductance of a head 40 at LH with the resistance set at RH respectively. With use of this equivalent circuit, the frequency characteristics of a record current become flat up to the frequency fY of about 10MHz. In this case, the level of the record current drops suddenly as shown by a curve 5 if no resistance R1 exists. While the level of the record current has just a slight drop with the frequency fZ of about 5MHz as shown by a curve 6 if no resistance R2 exists. Therefore the resistance R2 can be excluded. |
