1990-06-26
1991-12-31
Adams, Russell E.
G03B 1336
Patent
active
050775715
ABSTRACT:
An electric focusing apparatus comprises a focusing optical system, a focus adjusting motor, transmitting means for transmitting the drive force of the focus adjusting motor to the focusing optical system, drive amount detecting means for detecting the drive amount of the focus adjusting motor, movement limit detecting means for detecting a first drive stopping position in which the focusing optical system is driven in one direction by the focus adjusting motor and is stopped by one movement limit and a second drive stopping position in which the focusing optical system is driven in the other direction by the focus adjusting motor and is stopped by the other movement limit, planned drive amount memory means for memorizing a planned drive amount preset by one movement limit and the other movement limit of the focusing optical system, and backlash amount calculatng means for calculating the backlash amount of the transmitting means on the basis of the drive amount detected by the drive amount detecting means during the time from after the movement limit detecting means detects the first drive stopping position until it detects the second drive stopping position, and the planned drive amount memorized by the planned drive amount memory means.
REFERENCES:
patent: 4477167 (1984-10-01), Ishikawa et al.
patent: 4537487 (1985-08-01), Taniguchi et al.
patent: 4745425 (1988-05-01), Kusaka
patent: 5008605 (1991-04-01), Ohara et al.
Shiokama Yoshiharu
Takayama Toru
Adams Russell E.
Nikon Corporation
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