US 7,405,762 B2Granted

Camera having AF function

AssigneeOlympus Corporation

InventorsOsamu Nonaka, Minoru Hara

Life of this patent

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Abstract

A camera having an electronic image pickup element and a distance-measuring circuit that uses light signals obtained from light images of a plurality of distance-measuring areas set in a photographing screen to select a main subject and measure the distance to the subject. The camera has a focusing component, operating when the position of the main subject cannot be identified by the distance-measuring circuit, to divide the photographing screen into a plurality of areas to identify an area in which the main subject is present on the basis of a luminance distribution obtained from the areas other than those overlapping the distance-measuring areas. The focusing component focuses a photographing lens on the position of the highest contrast signal while scanning the lens position of the photographing lens.

Claims6

Dependent claims

A camera acquiring an image of a subject using an electronic image pickup element, the camera comprising:

a photographing lens which guides a luminous flux from the subject to the electronic image pickup element;
a driving mechanism which drives a focusing lens included in the photographing lens;
focus detecting circuit based on a phase difference detecting system to detect a focus state of the focusing lens for a particular area including a central part of a photographing composition;
a light source which radiates the subject with an illumination light;
and
a CPU that calculates a focus position of the focusing lens on the basis of a detection result from the focus detecting circuit to drivingly control the driving mechanism, wherein if the CPU determines that the output from the focus detecting circuit is not suitable for the focusing operation although the light source radiates the subject with the illumination light, and that a quantity of a part of the illumination light reflected by the subject is greater than a predetermined value, the CPU adjusts the focus state of the photographing lens by a mount-climbing system using an image signal, in a lower part of the photographing composition excluding the area for which the focus state is detected by the focus detecting circuit, of all image signals outputted by the electronic image pickup element.

3 more elements

A camera acquiring an image of a subject using an electronic image pickup element, the camera comprising:

a photographing lens which guides a luminous flux from the subject to the electronic image pickup element;
a phase difference auto focusing portion based on a phase difference detecting system, which detects a focus state of the photographing lens and drives the photographing lens to a focusing position based on a result of the detection, the phase difference auto focusing portion detecting the focus state of the photographing lens for a particular area including a central part of a photographing composition;
a mount-climbing auto focusing portion, which adjusts the focus state of the photographing lens based on a mount-climbing system using an image signal outputted by the electronic image pickup element, the mount-climbing auto focusing portion using the image signal for an area excluding the area for which the focus state is detected by the phase difference auto focusing portion;
an illuminating portion including a light source which radiates the subject with an illumination light and detecting a quantity of a part of the illumination light reflected by the subject;
a determining portion which determines whether focusing by the phase difference auto focusing portion is available or not;
and
a controlling portion, which selects either focusing by the phase difference auto focusing portion or focusing by the mount-climbing auto focusing portion based on a result of the determination by the determining portion and the detected quantity of light.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/768,633Filed 30 Jan 2004
Priority: JP 2003-0273614 Feb 2003
Published: US 2004/0183939 A123 Sep 2004
Granted: 29 Jul 2008
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H04N 23/672
Focus control based on electronic image sensor signals: based on the phase difference signals
G02B 7/32
Using parallactic triangle with a base line: using active means, e.g. light emitter
H04N 23/673
Focus control based on electronic image sensor signals: based on contrast or high frequency components of image signals, e.g. hill climbing method
H04N
Pictorial communication