| 摘要 |
PURPOSE:To generate a sound with good tone color which is rich in harmonic components and good sound spread, from a speaker by detecting only the string vibrations in the direction normal to the plane containing the string support member of the strings. CONSTITUTION:Let us assume a string 1 moves in a Y direction. As a result, the shadow caused by the string 1 also moves to the positive direction and an output current I1 of a position detection element PSD 6 becomes smaller than I2. Therefore, a difference (I1-I2) of two output currents I1 and I2 becomes small. When the string 1 moves toward a negative (down) direction, the shadow moves to the negative direction and the output current I1 of the PSD 6 becomes larger than I2. And the difference between two output currents I1 and I2 becomes large. In a current/voltage converting and subtracting circuit 8, two output currents I1 and I2 outputted from the PSD 6 are converted to voltages, respectively and subtracting each voltage so as to output a voltage which corresponds to the difference between two output currents I1 and I2. And a differentiation circuit 9 is switched by a changeover switch SW. |
