| 摘要 |
PURPOSE:To always detect the center part of an intermusic space regardless of the width or the before-after relation of the intermusic space, by providing a logical circuit which decides the rise of the output pulse of a comparator as an intermusic space. CONSTITUTION:The light emitted from a light emitting diode 1 is reflected by a record disk and received at a phototransistor 2. The voltage generated across a load R2 is amplified by an operational amplifier 3. A capacitor C1 and a resistance R4 connected to the output side of the amplifier 3 constitute a high pass filter HPF and eliminate the DC component as well as to increase the output ratio between an intermusic space and a sound groove. The output of the HPF is compared with the comparing voltage decided by the division ratio between resistances R5 and R6 through a comparator 4. Then the output of the HPF is converted into pulses and fetched to a microcomputer 5. The fall of the output pulse of the comparator 4 is detected by a logical circuit provided in the computer 5, and the intermusic space signal is extracted. |
