Photography – With exposure objective focusing means – focusing aid – or... – Reliability of focus/distance signal
Reexamination Certificate
2001-01-24
2004-12-28
Adams, Russell (Department: 2851)
Photography
With exposure objective focusing means, focusing aid, or...
Reliability of focus/distance signal
C396S106000, C396S122000, C396S123000
Reexamination Certificate
active
06836618
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a distance-measuring device for independently measuring distances to a plurality of distance-measured points, and to the improvement of a camera.
2. Description of the Related Art
Hitherto, various multipoint-distance-measuring devices have been proposed. A device is disclosed in, for example, Japanese Patent Laid-Open No. 6-331883, in which a plurality of distance-measured points are classified into groups in accordance with the position of and the distance to the distance-measured points, and the mean value of distances to the distance-measured points in each group is calculated. Another device is disclosed in, for example, Japanese Patent Laid-Open No. 59-193307, in which a smallest measured-distance to be used as focus adjustment data is selected among the mean value of distances to a plurality of visual fields, a distance value to a central visual-field, and distance values to the plurality of visual fields. Another device is disclosed in, for example, Japanese Patent Laid-Open No. 63-163830, in which a weighted average value is calculated.
However, in the known distance measuring devices, when the distance-measured points in all the visual fields are classified into groups and the mean values of the measured distances are calculated, a release time lag is produced due to an elongated calculation time. When using a mean value of distances, sharp focus cannot be obtained while generally intending to focus at one point in a visual field. In a device in which priority is given to a short distance range, the shutter cannot be released when even one of the distance-measured points is disposed at a shorter distance than a shortest permissible distance. Sometimes, a better photograph can be taken when the camera does not focus on an object disposed at the shortest distance because the object in the short distance range also has a certain depth.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a distance-measuring device in which distances to a plurality of distance-measured points are individually measurable.
It is another object of the present invention to provide a camera using a distance-measuring device in which the distances to a plurality of distance-measured points are individually measurable.
To these ends, according to an aspect of the present invention, a distance-measuring device for measuring individual distances to a plurality of distance-measured regions includes a selection circuit for selecting at least one first measured distance-value by excluding at least one second measured distance-value, the second measured distance-value being not smaller than a predetermined distance value, from individually measured distance-values to the plurality of distance-measured regions; and a computation circuit for computing an auto-focusing data value in accordance with the measured distance-value selected by the selection circuit.
According to another aspect of the present invention, a camera including a distance-measuring device for measuring individual distances to a plurality of distance-measured regions includes a selection circuit for selecting at least one first measured distance-value by excluding at least one second measured distance-value, the second measured distance-value being not smaller than a predetermined distance value, from individually measured distance-values to the plurality of distance-measured regions; a computation circuit for computing an auto-focusing data value in accordance with the measured distance-value selected by the selection circuit; and a driving circuit for driving an image-forming lens in accordance with the auto-focusing data value computed by the computation circuit.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.
REFERENCES:
patent: 4238153 (1980-12-01), Imura
patent: 4575211 (1986-03-01), Matsumura et al.
patent: 4943824 (1990-07-01), Nabeshima et al.
patent: 5249011 (1993-09-01), Sakai
patent: 5264892 (1993-11-01), Nonaka et al.
patent: 5313245 (1994-05-01), Konishi
patent: 5552853 (1996-09-01), Muramatsu et al.
patent: 5589911 (1996-12-01), Nonaka
patent: 59-193307 (1984-11-01), None
patent: 63-163830 (1988-07-01), None
patent: 6-331883 (1994-12-01), None
Adams Russell
Blackman Rochelle
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