| 摘要 |
PURPOSE:To suppress sliding friction powder to the minimum while preventing scattering and piling on an internal printed board by limitting the sliding contact parts with a button frame only to an operating button, while forming a reassessed doorcase part on a square periphery of a supporting frame side part of a photoreflection frame. CONSTITUTION:An engaging state of a button frame 1 and an operating button 2 is so made that the shape of the operating button 2 is unevenly formed and the maximum external sizes L1, L2 of a projection part may slidingly contact with a guide square hole part of the button frame 1 in order to reduce the sliding contact surface both of them to the utmost for avoiding generation of sliding friction powder. On the other hand, the external size of a lens 3 combined with the operating button 2 is made to be smaller enough than the external size of the operating button 2 to avoid sliding contact. Further, the external sizes of a photoreflection frame 4, in which the operating button 2 and the lens are combined, are made about the same sizes with the maximum external sizes l1 and l2 of the recessed part of the operating button 2. And, a recessed doorcase groove part consisting of a part A and a part B is formed on a square periphery of the side of a supporting frame of the photoreflecting frame 4. |
