Title:
AUTOMATIC FOCUS ADJUSTING DEVICE
Document Type and Number:
Japanese Patent JPS6427372
Kind Code:
A
Abstract:
PURPOSE:To contrive to improve the processing speed of calculation of focal point by providing an arithmetic means calculating a focal point of an image pickup lens by a digital video signal extracted by a video signal extraction means and a focus control means applying focus control to the image pickup lens according to the focal point calculated by the arithmetic means. CONSTITUTION:In starting video recording in the auto focus mode (AF mode), a gate circuit 14 extracts a signal to be focused from a video signal and an extracted signal is integrated for a prescribed period by a digital integration circuit 16 and the result is fed to a CPU 22 as an AF evaluation data 21. Then the CPU 22 compares the present focus (fn) with a focus (fn-1) in one step preceding time and in case of fn>=fn-1, that is, the focus is in the matching direction (forward direction), the AF motor 26 is driven at a point of time of the fn to match the focus further. In case of fn<=fn-1, that is, the focus is deviated further from the fn, an AF driver instruction signal 23 to reverse the AF motor 26 is sent to a motor driver 24.
Inventors:
KAWAMURA HISANOBU
Application Number:
JP18234987A
Publication Date:
January 30, 1989
Filing Date:
July 23, 1987
Export Citation:
Assignee:
FUJI PHOTO FILM CO LTD
International Classes:
G02B7/36; G02B7/28; H04N5/232; (IPC1-7): G02B7/11; H04N5/232
Attorney, Agent or Firm:
Takao Katori