Focusing apparatus, control method of focusing apparatus, and recording medium storing focus adjustment program

Patent metadata

Field	Value
Publication number	US-10859790-B2
Application number	US-201916423110-A
Country	US
Kind code	B2
Filing date	May 27, 2019
Priority date	Nov 28, 2016
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

A focusing apparatus includes processing circuitry. The processing circuitry is configured to select an AF area indicating a defocus amount closest to a calculated moving object prediction equation among the latest defocus amounts detected for the plurality of AF areas, in a case where the moving object prediction equation is determined as being established, and the driving direction is determined as being the close-range direction. The moving object prediction equation is determined as being established when a divergence amount between the defocus amount equal to or larger than a predetermined number included in the history and the calculated moving object prediction equation is equal to or lower than a predetermined value.

First claim

What is claimed is:

1. A focusing apparatus detecting a defocus amount repeatedly for each of a plurality of AF areas and selecting an AF area based on the defocus amount to perform focus adjustment, wherein
the focusing apparatus comprises processing circuitry that is configured to:
calculate a moving object prediction equation based on a history of a plurality of the repeatedly detected defocus amounts;
perform a first determination as to whether or not the moving object prediction equation may be established, the moving object prediction equation being determined as being established when a divergence amount between a plurality of the defocus amounts equal to or larger than a predetermined number within a past predetermined time from a current time included in the history and the calculated moving object prediction equation is equal to or lower than a predetermined value, and a second determination as to whether a driving direction of a focus lens for keeping track of a moving subject calculated from the moving object prediction equation is a close-range direction or an infinite direction; and
in a case where the moving object prediction equation is determined as being established in the first determination, and the driving direction is determined as being the close-range direction in the second determination, select an AF area indicating a defocus amount closest to the moving object prediction equation among the latest defocus amounts detected for the plurality of AF areas.

2. The focusing apparatus according to claim 1 , wherein the processing circuitry further performs a third determination as to whether or not a defocus amount that is a minimum value of an absolute value of a positive defocus amount, and is a defocus amount smaller than a predetermined factor of times of a minimum value of an absolute value of a negative defocus amount exists among the plurality of detected defocus amounts, or as to whether or not the positive defocus amount is sufficiently small, and, in which case precision of the moving object prediction equation is insufficient in the second determination, or in which case the driving direction is determined as an infinite direction in the second determination, the processing circuitry selects an AF area that indicates the defocus amount satisfying the third determination.

3. The focusing apparatus according to claim 2 , wherein, in a case where the defocus amount that satisfies the third determination does not exist when the moving object prediction equation is determined as not being established in the first determination or when the driving direction is determined as the infinite direction in the second determination, the processing circuitry selects an AF area indicating the minimum value of the absolute value of the negative defocus amount.

4. The focusing apparatus according to claim 1 , further comprising a focusing instruction unit that instructs a start of focus adjustment, wherein
the processing circuitry selects an AF area indicating a maximum value of a positive defocus amount among the plurality of defocus amounts until an instruction to start focus adjustment is issued from the focusing instruction unit, or until a focus determination is once made after the start instruction is issued.

5. The focusing apparatus according to claim 1 , wherein the processing circuitry further sets a sensitivity of focus adjustment, and, in a case where the set sensitivity is higher than a predetermined value, preferentially selects an AF area indicating a positive defocus amount among the plurality of defocus amounts.

6. The focusing apparatus according to claim 1 , further comprising tracking circuitry for tracking a subject, wherein
the processing circuitry selects an AF area based on a defocus amount indicated by the AF area within a predetermined range centered on a tracking position of the tracking circuitry.

7. The focusing apparatus according to claim 1 , further comprising face detection circuitry for detecting a face, wherein
the processing circuitry selects an AF area based on a defocus amount indicated by the AF area within a range of a face detected by the face detection circuitry.

8. The focusing apparatus according to claim 7 , further comprising:
a focusing instruction unit that instructs a start of focus adjustment;
a reliability determination circuitry that determines reliability regarding the detection of the defocus amount; and
pupil detection circuitry that detects a pupil within the range of the face detected by the face detection circuitry, wherein
the processing circuitry selects an AF area corresponding to a position of a pupil within the range of the face among the plurality of defocus amounts, or an AF area with high reliability until an instruction to start focus adjustment is issued from the focusing instruction unit, or until a focus determination is once made after the start instruction is issued.

9. The focusing apparatus according to claim 1 , further comprising a focusing instruction unit that instructs a start of focus adjustment, wherein
the processing circuitry performs the focus adjustment by correcting the defocus amount indicated by the selected AF area to a positive side by a predetermined amount.

10. The focusing apparatus according to claim 1 , further comprising a focusing instruction unit that instructs a start of focus adjustment, wherein
the processing circuitry performs focus determination by correcting a threshold for the focus determination to a negative side.

11. The focusing apparatus according to claim 1 , further comprising a storage unit that stores an optical correction amount relating to a defocus amount, wherein
the processing circuitry calculates the moving object prediction equation based on a history of a defocus amount obtained by correcting the detected defocus amount by the optical correction amount, and selects an AF area based on the corrected defocus amount.

12. The focusing apparatus according to claim 1 , wherein the processing circuitry further performs evaluation of accuracy of the moving object prediction equation in addition to the first determination.

13. A method for controlling a focusing apparatus, the focusing apparatus detecting a defocus amount repeatedly for each of a plurality of AF areas and selecting an AF area based on the defocus amount to perform focus adjustment, the method comprising:
calculating a moving object prediction equation based on a history of a plurality of the repeatedly detected defocus amounts;
performing a first determination as to whether or not the moving object prediction equation is established, the moving object prediction equation being determined as being established when a divergence amount between a plurality of the defocus amounts equal to or larger than a predetermined number within a past predetermined time from a current time included in the history and the calculated moving object prediction equation is equal to or lower than a predetermined value, and a second determination as to whether a driving direction of a focus lens for keeping track of a moving subject calculated from the moving object prediction equation is a close-range direction or an infinite direction; and
in a case where the moving object prediction equation is determined as being established in the first determination, and the driving direction is determined as the close-range direction in the second determination, selecting an AF area indicating a defocus amount closest to the moving object prediction equation among the latest defocus amounts detected for the plurality of AF areas.

14. The method according to claim 13 ,

Assignees

• Olympus Corp

Inventors

• Kikuchi Tetsuo
• Kunugi Kazumasa
• Yamazaki Yukie
• Hoshino Tomohiro

Classifications

• G02B7/36 Primary

  using image sharpness techniques {, e.g. image processing techniques for generating autofocus signals (image data processing per se G06T; in cameras having a solid state image sensor H04N23/67)} · CPC title

• H04N23/60

  Control of cameras or camera modules · CPC title

• H04N23/67

  Focus control based on electronic image sensor signals · CPC title

• H04N25/704

  Pixels specially adapted for focusing, e.g. phase difference pixel sets · CPC title

• H04N23/672

  based on the phase difference signals · CPC title