| 摘要 |
PURPOSE:To produce a large-sized thick plastic lens with precision in a short molding cycle, by compression molding wherein a high-frequency energy is employed to heat the mold surface. CONSTITUTION:The surface of a lens blank that is thicker than the intended lens and whose outer diameter is smaller than that of the intended lens is melted by a heated mold, and it is compressed followed by cooling to make the intended lens. In this method, the mold 2 is provided with a resonant chamber 8 that constitutes a resonant space in cooperation with the cavity surfaces 4, and a high-frequency energy is fed. That is, the high-frequency energy from an oscillator 5 is transmitted via a controller 6, and an impedance matching box 7 to the resonant chamber 8 (the reference numerals 11a-11e are waveguides), and due to the ohmic loss of the wall current generated on the cavity surfaces 4, the surface layers quickly heat up to reach a prescribed molding temperature within a short period (in case when a temperature detector 12 detects the set temperature, the controller stops the operation of the oscillator 5). |
