# US 2018/0027172 A1 · Focus adjusting apparatus, focus adjusting method, image capturing apparatus, and storage medium > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0027172 A1 - Document ID: US20180027172A1 - Status: Published application - Kind: A1 - Application number: 15/653,633 - Filed: 2017-07-19 - Published: 2018-01-25 - Earliest claimed: 2016-07-21 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Takayuki Akaguma - Web page: https://patentgrep.com/patent/US20180027172A1 ## CPC - G02B 7/34: using different areas in a pupil plane - G02B 7/28: Systems for automatic generation of focusing signals - G03B 3/10: Power-operated focusing - H04N 23/10: for generating image signals from different wavelengths - H04N 23/611: where the recognised objects include parts of the human body - H04N 23/672: {based on the phase difference signals} - H04N 25/704: Pixels specially adapted for focusing, e.g. phase difference pixel sets - G03B 13/36: Autofocus systems - H04N 23/63: by using electronic viewfinders - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A focus adjusting apparatus detects a first area of a subject and reliability of a tracking position from an image signal output from an image sensor on which a subject image is formed by an optical system, detects focus states of focus detection areas based on the image signal, determines an in-focus area for which focus adjustment of the optical system is to be performed, predicts a focus state in next focus detection based on a history of focus states of the in-focus area, and selects a second area from the focus detection areas. The first area is determined as the in-focus area in a case where a state in which the reliability is higher than a predetermined first threshold continues for a predetermined time period or longer, and the second area is determined as in-focus area otherwise. ## Claims ### Claim 1 A focus adjusting apparatus, comprising: a tracking unit that detects a first area of a subject to be tracked, and reliability of a tracking position from an image signal output from an image sensor that captures a subject image formed on the image sensor by an optical system; a focus detection unit that detects focus states of a plurality of focus detection areas based on the image signal that is output from the image sensor; a determination unit that determines an in-focus area for which focus adjustment of the optical system is to be performed; a prediction unit that predicts a focus state in next focus detection based on a history of focus states of the in-focus area detected by the focus detection unit; and a selection unit that selects a second area from the plurality of focus detection areas, wherein the determination unit determines the first area as the in-focus area in a case where a state in which the reliability is higher than a predetermined first threshold continues for a predetermined time period or longer, and determines the second area as the in-focus area in a case where the state does not continue for the predetermined time period. ### Claim 2 (depends on 1) The focus adjusting apparatus according to claim 1, wherein the selection unit selects the second area from predetermined part of the plurality of focus detection areas. ### Claim 3 (depends on 1) The focus adjusting apparatus according to claim 1, wherein, in a case where a difference between a focus state of the first area and the predicted focus state is within a predetermined first range, the determination unit determines the first area as the in-focus area regardless of the reliability. ### Claim 4 (depends on 1) The focus adjusting apparatus according to claim 1, wherein, in a case where the reliability is higher than the first threshold and a difference between a focus state of the second area and the predicted focus state is not within a second range, the determination unit determines the first area as the in-focus area. ### Claim 5 (depends on 1) The focus adjusting apparatus according to claim 1, wherein, in a case where the reliability is equal to or less than the first threshold and a difference between a focus state of the second area and the predicted focus state is within a second range, the determination unit determines the second area as the in-focus area. ### Claim 6 (depends on 1) The focus adjusting apparatus according to claim 1, wherein, in a case where the reliability is equal to or less than the first threshold and a difference between a focus state of the second area and the predicted focus state is not within a second range, the determination unit determines the in-focus area determined last time as the in-focus area. ### Claim 7 (depends on 1) The focus adjusting apparatus according to claim 1, wherein the predetermined time period is changed in accordance with at least one of the reliability and a difference between a focus state of the second area and the predicted focus state. ### Claim 8 (depends on 1) The focus adjusting apparatus according to claim 1, further comprising: a display unit that displays an image based on the image signal; a setting unit that sets an area corresponding to the in-focus area determined by the determination unit and an area that satisfies a predetermined condition, wherein the display unit superimposes a display that indicates the area set by the setting unit on the image. ### Claim 9 (depends on 8) The focus adjusting apparatus according to claim 8, wherein the predetermined condition is that a difference between the focus state of each of the part of the focus detection areas and the focus state of an area corresponding to the in-focus area is smaller than a predetermined threshold. ### Claim 10 (depends on 8) The focus adjusting apparatus according to claim 8, wherein the predetermined condition is that a difference between the focus state of an area corresponding to the in-focus area and a weighted focus state of each of the part of the focus detection areas is smaller than a predetermined threshold, wherein each weight is based on a distance from the in-focus area. ### Claim 11 An image capturing apparatus, comprising: an image sensor that outputs as image signal by capturing a subject image formed by an optical system; and a focus adjusting apparatus that comprises: a tracking unit that detects a first area of a subject to be tracked, and reliability of a tracking position from an image signal output from an image sensor that captures a subject image formed on the image sensor by an optical system; a focus detection unit that detects focus states of a plurality of focus detection areas based on the image signal that is output from the image sensor; a determination unit that determines an in-focus area for which focus adjustment of the optical system is to be performed; a prediction unit that predicts a focus state in next focus detection based on a history of focus states of the in-focus area detected by the focus detection unit; and a selection unit that selects a second area from the plurality of focus detection areas, wherein the determination unit determines the first area as the in-focus area in a case where a state in which the reliability is higher than a predetermined first threshold continues for a predetermined time period or longer, and determines the second area as the in-focus area in a case where the state does not continue for the predetermined time period. ### Claim 12 A focus adjusting method, comprising: detecting a first area of a subject to be tracked, and reliability of a tracking position from an image signal output from an image sensor that captures a subject image formed on the image sensor by an optical system; detecting focus states of a plurality of focus detection areas based on the image signal that is output from the image sensor; determining an in-focus area for which focus adjustment of the optical system is to be performed; predicting a focus state in next focus detection based on a history of focus states of the detected in-focus area; and selecting a second area from the plurality of focus detection areas, determining the first area as the in-focus area in a case where a state in which the reliability is higher than a predetermined first threshold continues for a predetermined time period or longer, and determining the second area as the in-focus area in a case where the state does not continue for the predetermined time period. ### Claim 13 (depends on 12) The focus adjusting method according to claim 12, further comprising: setting an area corresponding to the determined in-focus area and an area that satisfies a predetermined condition; and displays an image based on the image signal, and superimposes a display that indicates the set area on the image. ### Claim 14 A computer-readable storage medium having stored therein a program which is executable by a computer, the program having program codes for realizing the focus adjusting method that comprises: detecting a first area of a subject to be tracked, and reliability of a tracking position from an image signal output from an image sensor that captures a subject image formed on the image sensor by an optical system; detecting focus states of a plurality of focus detection areas based on the image signal that is output from the image sensor; determining an in-focus area for which focus adjustment of the optical system is to be performed; predicting a focus state in next focus detection based on a history of focus states of the detected in-focus area; and selecting a second area from the plurality of focus detection areas, determining the first area as the in-focus area in a case where a state in which the reliability is higher than a predetermined first threshold continues for a predetermined time period or longer, and determining the second area as the in-focus area in a case where the state does not continue for the predetermined time period.