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US 4,538,892 AGranted
Automatic focus control system
AssigneeCanon Kabushiki Kaisha
InventorsShinji Sakai, Yoshihito Harada, Akira Ishizaki, Takashi Kawabata
Life of this patent
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Abstract
This specification discloses an energizing control of a drive element for driving a motor or the like which drives a focusing lens. The energization is controlled on the basis of the detection of whether or not the position of the focusing lens is within the quasi-in-focus state, and when the continuation of the quasi-in-focus state for a predetermined time period or more is detected, energization of the driving element is stopped.
Claims3
An automatic focus control system comprising:
- (a) distance detecting means for outputting a distance detective signal corresponding to a distance of an object to be photographed;
- (b) drive means for driving a focusing lens;
- (c) quasi-in-focus range detecting means for outputting, on the basis of the distance detection signal from said distance detecting means, a signal indicative of whether or not the focusing lens is in a quasi-in-focus range;
- (d) in-focus range detecting means for outputting, on the basis of the distance signal from said distance detecting means, a signal indicative of whether or not the focusing lens is in-focus;
- and
- (e) quasi-in-focus range continuation detecting means having memory means for receiving the output signal from said quasi-in-focus range detecting means indicating that said focusing lens is in the quasi-in-focus state and for outputting a control signal when said memory means receives a plurality of signals indicating that said focusing lens is in the quasi-in-focus range;
- wherein said drive means is controlled on the basis of the control signal from said memory means.
4 more elements
An automatic focus control system comprising:
- (a) distance detecting means for outputting a distance detection signal corresponding to a distance of an object to be photographed;
- (b) drive means for driving a focusing lens;
- (c) quasi-in-focus range detecting means for outputting, on the basis of the distance detection signal from said distance detecting means, a signal indicative of whether or not the focusing lens is in a quasi-in-focus range
- (d) in-focus range detecting means for outputting, on the basis of the distance signal from said distance detecting means, a signal indicative of whether or not the focusing lens is in-focus;
- and
- (e) quasi-in-focus range continuation detecting means having time-constant means for receiving the output signal from said quasi-in-focus range detecting means indicating that said focusing lens is in the quasi-in-focus range and for outputting a control signal after the predetermined time, said drive means being stopped in accordance with the control signal from said time-constant means.
3 more elements
An automatic focus control system comprising:
- (a) distance detecting means for outputting a distance signal corresponding to a distance of an object to be photographed;
- (b) lens position signal generator means for outputting a signal corresponding to a position of a focusing lens;
- (c) drive means for driving a focusing lens;
- (d) means for receiving the output of said lens position signal generator means and the output signal from said distance detecting means to output a focus state signal;
- (e) first means, based on the focus state signal, for outputting a signal indicating that said focusing lens is in the quasi-in-focus range;
- (f) second means, based on the focus state signal, for outputting a signal indicating that said focusing lens is in-focus;
- and
- (g) time control means for receiving the signal from said first means and for stopping the energization of said drive means after a predetermined time from the receipt of the signal from said first means.
5 more elements
Dependencies are inferred from the claim text.