| 摘要 |
PROBLEM TO BE SOLVED: To provide a cam mechanism for a lens barrel being rotatable at a time in the state where an operation ring is held by making the rotational angle of a rotary barrel small in the case of totally extending a straight advance barrel even if it is a zoom lens having a high zoom ratio. SOLUTION: The lens barrel is constituted of the rotary barrel 3 and the straight advance barrel 2, and has the cam mechanism installed in the rotary barrel 3 in order to making the advance barrel 2 straight move by driving and rotating the rotary barrel 3. Cam grooves 4, 5, 6 and 7 installed on the rotary barrel 3 form circular shape constituting a closed loop, and a guide pin 13 profiling the closed loop is a one-direction guide mechanism that starts from a starting point 8 and returns to the starting point 8, and the straight advance barrel 2 is extended once by the reciprocative rotating operation of the rotary barrel 3. Then, the height of the guide pin 13 fit and inserted in the circular-shaped cam grooves is flexible and the pin 13 has structure that it is energized in a compressing direction. COPYRIGHT: (C)2005,JPO&NCIPI
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