| 摘要 |
PURPOSE:To improve the sound quality and the sound volume adjustment by condensing an optical signal with a specific wavelength from an optical signal transmission section, passing the signal, giving it to a photoelectric conversion element, converting it into an electric signal, adjusting the intensity of the electric signal with a mechanical shield plate and supplying the result to an earphone speaker. CONSTITUTION:A light of a sound signal A converted into an optical signal B with a specific wavelength at a sender side and sent to space is received by a condenser lens 2. A wavelength filter 3 is utilized to pass only a specific wavelength from among various wavelengths included in a natural light and an external disturbance light such as a fluorescent light existing in space. With the external disturbance eliminated, the signal light is delivered to a shield plate 4 arranged closely to one face of the wavelength filter 3. The shield plate 4 shields the light passing through the wavelength filter 3 mechanically to adjust the luminous quantity and sends the result to a photoelectric conversion element 5. The photoelectric conversion element 5 converts only the specific wavelength, that is, the optical signal B equivalent to the sound signal A into an electric signal. Thus, the sound signal with excellent sound quality is subject to mechanical sound volume adjustment. |
