| 摘要 |
PURPOSE:To attain highly accurate position detection, to miniaturize a zoom lens and a camera with the zoom lens, and to obtain high magnification and further, pleasant operability CONSTITUTION:Two PSDs 23 and 24 are arranged in parallel, and a slit plate 11 composed of the slit lines of equal/unequal intervals corresponding to the PSDs 23 and 24, and a uncontact position detecting encoder composed of a small-sized sensor group are provided on a lens. The output current of the PSD is converted into a voltage, and then, inputted into an A/D converting circuit 302, and a comparator 322 exchanging the sum signal of an output voltage to a logic signal, so that high speed motor control can be carried out through the use of the output of the comparator during a zooming action, and simultaneously, the result of A/D conversion is calculated after the zooming action is stopped. |
