| 摘要 |
PURPOSE:To simplify the construction of a variable powe mechanism and a control circuit, by varying magnifications at plural limited stages with a device which stops mechanically a zoom lens in accordance with the signal from a sensor for detecting the movement in the position of a set magnification. CONSTITUTION:A motor 20 with a speed reducer which drives a zoom lens rest 4 has a function for suppressing the rotation of said rest on stopping but has no function for detecting the rotating position of an output shaft. Said motor has a pulley 21 and moves the reset 4 forward and backward along a guide bar 3. The detection of the reset 4 is accomplished by the slits 26A-26C of a slip plate 25 and a transmission type sensor 27, which detects the 1st reduction position (low reduction position)(neighborhood) and an unmagnification position (neighborhood). An origin detector 28 detects the 2nd reduction position (high reduction position)(neighborhood) in the end part. A device 30 which stops the rest 4 in each magnification position has a plate 31 for fixing and stopping on a base plate 3 and an unlocking plate 33 which moves on the plate 31 when a magnet 32 is de-energized. Both plates 31, 33 has the contact surfaces corresponding to the 1st reduction, unmagnification, magnification and the 2nd reduction positions of the rest 4. |
