US4914282A
Expired / Lapsed
US
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Focus detection system employing multiple area light distribution sensors
Assignee: Canon Inc
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Filing: 1989-01-09
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Granted: 1990-04-03
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Expires: 2009-01-09
Abstract
Abstract A focus detection system for detecting a focus state of an object lens, includes an optical device for forming first and second light distributions corresponding to first and second images having light fluxes passing through the different parts of a pupila of the object lens. The positional relationship between the two light distributions varies in accordance with the focus state of the object lens. First and second sensors sense the first and second light distributions. A signal processor for processing output signals from the first and second sensors detect the focus state of the object lens in accordance with the positional relationships between the two light distributions. The signal processor processes the signals from the first and second sensors in accordance with a predetermined formula to obtain the positional relationship between the two images to determine a degree of coincidence of the two light distributions. The signal processing means provides an output signal in accordance with the degree of coincidence of the two light distributions.
Inventors
- 👤 Akira Akashi
- 👤 Akira Ishizaki
- 👤 Akira Hiramatsu
- 👤 Yasuo Suda
- 👤 Keiji Ohtaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 13:14
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/34
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
222 words
A focus detection system for detecting a focus state of an object lens, comprising: optical means for forming first and second light distributions respectively corresponding to first and second images having light reflective fluxes passing through the different parts of the object lens, whereby the positional relationship between said first and second light distributions varies in accordance with the focus state of the object lens; first and second sensing means for sensing said first and second light distributions, said first and second sensing means each having a plurality of sensor elements; and signal processing means for processing output signals from said first and second sensing means to detect the focus state of the object lens in accordance with the positional relationship between the two light distributions; said signal processing means processing the signals from said first and second sensing means in accordance with a predetermined formula to determine a degree of coincidence of the said light distributions, said signal processing means providing an output signal in accordance with the degree of similarity of said two light distributions, and said signal processing means detecting a focus state of the object lens by processing signals from two groups of sensor elements being provided in corresponding positions, and each having the same number of sensor elements, which number is smaller than the total number thereof.
Claim 2
Dependent Claim
222 words
A focus detection system for detecting a focus state of an object lens, comprising: optical means for forming first and second light distributions respectively corresponding to first and second images having light reflective fluxes passing through the different parts of the object lens, whereby the positional relationship between said first and second light distributions varies in accordance with the focus state of the object lens; first and second sensing means for sensing said first and second light distributions, said first and second sensing means each having a plurality of sensor elements; and signal processing means for processing output signals from said first and second sensing means to detect the focus state of the object lens in accordance with the positional relationship between the two light distributions; said signal processing means processing the signals from said first and second sensing means in accordance with a predetermined formula to determine a degree of coincidence of the said light distributions, said signal processing means providing an output signal in accordance with the degree of similarity of said two light distributions, and said signal processing means detecting a focus state of the object lens by processing signals from two groups of sensor elements being provided in corresponding positions, and each having the same number of sensor elements, which number is smaller than the total number thereof.
Claim 3
Dependent Claim
70 words
A focus detection system according to claim 1 wherein said first and second sensing means each including a plurality of photo-electric conversion devices, and the degree of coincidence U is given by ##EQU9## where a(i) is an output from an i-th photo-electric conversion device of said first sensing means, b(i) is an output from an i-th photo-electric conversion device of said second sensing means, and P is a positive number.
Claim 4
Dependent Claim
78 words
A focus detection system according to claim 1 wherein said first and second sensing means each including a plurality of photo-electric conversion devices, and the degree of coincidence U is given by ##EQU10## where a(i) is an output from an i-th photo-electric conversion device of said first sensing means, b(i) is an output from as i-th photo-electric conversion device of said second sensing means, min represents a smaller one of two real numbers x and y, and max
Claim 5
Dependent Claim
47 words
A focus detection system according to claim 1 wherein the outputs of said first and second sensing means are divided into a plurality of partially overlapping areas for each of said first and second images. represents a larger one of the two real numbers x and y.
Claim 6
Dependent Claim
42 words
A focus detection system according to claim 1, further comprising display means which displays the state of the focus detection in accordance with the degree of coincidence of the two light distributions in response to the output from said signal processing means.
Claim 7
Dependent Claim
209 words
A focus detection system for detecting a focus state of an object lens, comprising: optical means including an object lens for forming first and second light distributions respectively corresponding to first and second images having respective light fluxes passing through different parts of a pupil of the object lens wherein the positional relationship between said first and second light distributions varies with the focus state of said object lens; first and second sensing means for sensing said first and second images, respectively; and signal processing means for processing output signals from said first and second sensing means to obtain the positional relationship between said two images to detect the focus state of the object lens; said signal processing means processing the signals from said first and second sensing means in accordance with a predetermined formula to determine a degree of coincidence of the two images, and when the degree of coincidence is larger than a predetermined value, dividing the outputs of said first and second sensing means into a plurality of areas for each of said first and second images, determining a value representing the positional relationship of said light distributions corresponding to said first and second images for each area, and determining the focus based on said values.
Claim 8
Dependent Claim
209 words
A focus detection system for detecting a focus state of an object lens, comprising: optical means including an object lens for forming first and second light distributions respectively corresponding to first and second images having respective light fluxes passing through different parts of a pupil of the object lens wherein the positional relationship between said first and second light distributions varies with the focus state of said object lens; first and second sensing means for sensing said first and second images, respectively; and signal processing means for processing output signals from said first and second sensing means to obtain the positional relationship between said two images to detect the focus state of the object lens; said signal processing means processing the signals from said first and second sensing means in accordance with a predetermined formula to determine a degree of coincidence of the two images, and when the degree of coincidence is larger than a predetermined value, dividing the outputs of said first and second sensing means into a plurality of areas for each of said first and second images, determining a value representing the positional relationship of said light distributions corresponding to said first and second images for each area, and determining the focus based on said values.
Claim 9
Dependent Claim
70 words
A focus detection system according to claim 6 wherein said first and second sensing means each including a plurality of photo-electric conversion devices, and the degree of coincidence U is given by ##EQU11## where a(i) is an output from an i-th photo-electric conversion device of said first sensing means, b(i) is an output from an i-th photo-electric conversion device of said second sensing means, and P is a positive number.
Claim 10
Dependent Claim
93 words
A focus detection system according to claim 6 wherein said first and second sensing means each including a plurality of photo-electric conversion devices, and the degree of coincidence U is given by ##EQU12## where a(i) is an output from an i-th photo-electric conversion device of said first sensing means, b(i) is an output from an i-th photo-electric conversion device of said second sensing means, min{x, y } represents a smaller one of two real numbers x and y, and max{x, y} represents a larger one of the two real numbers x and y.
Claim 11
Dependent Claim
35 words
A focus detection system according to claim 6 wherein the outputs of said first and second sensing means are divided into a plurality of partially overlapping areas for each of said first and second images.
Claim 12
Independent Claim
165 words
A method for detecting a focus state of an object lens, comprising the steps of: forming first and second images whose positional relationship varies with the focus state of said object lens; sensing said first and second images by first and second sensing means each having a plurality of sensor elements; and processing output signals obtained in said sensing step to detect the focus state of the object lens; said signal processing steps processing the signals obtained from said sensing step in accordance with a predetermined formula to determine a degree of coincidence of said two light distributions and said signal processing step dividing an output signal is accordance with the degree of coincidence of said two light distributions, and said signal processing steps detecting a focus state of said object lens by processing signals from two groups of said sensor elements being provided in corresponding positions, and each having the same number of sensor elements, which number is smaller than the total number thereof.
Claim 13
Independent Claim
165 words
A method for detecting a focus state of an object lens, comprising the steps of: forming first and second images whose positional relationship varies with the focus state of said object lens; sensing said first and second images by first and second sensing means each having a plurality of sensor elements; and processing output signals obtained in said sensing step to detect the focus state of the object lens; said signal processing steps processing the signals obtained from said sensing step in accordance with a predetermined formula to determine a degree of coincidence of said two light distributions and said signal processing step dividing an output signal is accordance with the degree of coincidence of said two light distributions, and said signal processing steps detecting a focus state of said object lens by processing signals from two groups of said sensor elements being provided in corresponding positions, and each having the same number of sensor elements, which number is smaller than the total number thereof.
Claim 14
Dependent Claim
74 words
A focus detection method according to claim 10 wherein first and second sensing means used in said sensing step each including a plurality of photoelectric conversion devices, and the degree of coincidence U is given by ##EQU13## where a(i) is an output from an i-th photo-electric conversion device of said first sensing means, b(i) is an output from an i-th photo-electric conversion device of said second sensing means, and P is a positive number.
Claim 15
Dependent Claim
96 words
A focus detection method according to claim 10 wherein first and second sensing means used in said sensing ste each including a plurality of photo-electric conversion devices, and the degree of coincidence U is given by ##EQU14## where a(i) is an output from an i-th photo-electric conversion device of said first sensing means, b(i) is an output from an i-th photo-electric conversion device of said second sensing means, min{x, y} represents a smaller one of two real numbers x and y, and max{x, y} represents a larger one of the two real numbers x and y.
Claim 16
Dependent Claim
35 words
A focus detection method according to claim 10 wherein the outputs of said first and second sensing means are divided into a plurality of partially overlapping areas for each of said first and second images.
Claim 17
Independent Claim
171 words
A method for detecting a focus state of an object lens, comprising the steps of: forming first and second light distributions corresponding to first and second images having light fluxes passing through different object lens wherein the positional relationship between said first and second light distributions varies with the focus state of said object lens; sensing said first and second images, respectively; and processing output signals obtained in said sensing step to detect the focus state of said object lens; said signal processing step processing the signal obtained in said sensing step in accordance with a predetermined formula to determine a degree of coincidence of the two image, and when the degree of coincidence is larger than a predetermined value, dividing the outputs obtained in said sensing step into a plurality of areas for each of said first and second images, determining a value representing the positional relationship of said two light distributions corresponding to said first and second images for each area, and detecting the focus based on said values.
Claim 18
Independent Claim
171 words
A method for detecting a focus state of an object lens, comprising the steps of: forming first and second light distributions corresponding to first and second images having light fluxes passing through different object lens wherein the positional relationship between said first and second light distributions varies with the focus state of said object lens; sensing said first and second images, respectively; and processing output signals obtained in said sensing step to detect the focus state of said object lens; said signal processing step processing the signal obtained in said sensing step in accordance with a predetermined formula to determine a degree of coincidence of the two image, and when the degree of coincidence is larger than a predetermined value, dividing the outputs obtained in said sensing step into a plurality of areas for each of said first and second images, determining a value representing the positional relationship of said two light distributions corresponding to said first and second images for each area, and detecting the focus based on said values.
Claim 19
Dependent Claim
74 words
A focus detection method according to claim 14 wherein first and second sensing means used in said sensing step each including a plurality of photo-electric conversion devices, and the degree of coincidence U is given by ##EQU15## where a(i) is an output from an i-th photo-electric conversion device of said first sensing means, b(i) is an output from an i-th photo-electric conversion device of said second sensing means, and P is a positive number.
Claim 20
Dependent Claim
96 words
A focus detection method according to claim 14 wherein first and second sensing means used in said sensing step each including a plurality of photo-electric conversion devices, and the degree of coincidence U is given by ##EQU16## where a(i) is an output from an i-th photo-electric conversion device of said first sensing means, b(i) is an output from an i-th photo-electric conversion device of said second sensing means, min{x, y} represents a smaller one of two real numbers x and y, and max{x, y} represents a larger one of the two real numbers x and y.
Claim 21
Dependent Claim
35 words
A focus detection method according to claim 14 wherein the outputs of said first and second sensing means are divided into a plurality of partially overlapping areas for each of said first and second images.
Claim 22
Dependent Claim
240 words
A focus detection system for detecting a focus state of an object lens, comprising: optical means for forming first and second light distributions respectively corresponding to first and second images having light reflective fluxes passing through the different parts of the object lens, whereby the positional relationship between said first and second light distributions varies in accordance with the focus state of the object lens; first and second sensing means for sensing said first and second light distributions, said first and second sensing means each having a plurality of sensor elements; and signal processing means for processing output signals from said first and second sensing means to detect the focus state of the object lens in accordance with the positional relationship between the two light distributions, said signal processing means performing a correlational calculation by using the signals from said each of said plurality of sensor elements and evaluating said signals in accordance with a predetermined conditional formula, said signal processing means adopting the result of the correlational calculation when the evaluation satisfies the conditional formula and, when the evaluation does not satisfy the conditional formula, performing another correlational calculation to adopt the result as information of the focus adjusting condition on the basis of signals from continuous sensor elements the number of which is smaller than the number of elements in each of said plurality of sensor elements and which correspond with each other in the positional relationship thereof.
Claim 23
Dependent Claim
240 words
A focus detection system for detecting a focus state of an object lens, comprising: optical means for forming first and second light distributions respectively corresponding to first and second images having light reflective fluxes passing through the different parts of the object lens, whereby the positional relationship between said first and second light distributions varies in accordance with the focus state of the object lens; first and second sensing means for sensing said first and second light distributions, said first and second sensing means each having a plurality of sensor elements; and signal processing means for processing output signals from said first and second sensing means to detect the focus state of the object lens in accordance with the positional relationship between the two light distributions, said signal processing means performing a correlational calculation by using the signals from said each of said plurality of sensor elements and evaluating said signals in accordance with a predetermined conditional formula, said signal processing means adopting the result of the correlational calculation when the evaluation satisfies the conditional formula and, when the evaluation does not satisfy the conditional formula, performing another correlational calculation to adopt the result as information of the focus adjusting condition on the basis of signals from continuous sensor elements the number of which is smaller than the number of elements in each of said plurality of sensor elements and which correspond with each other in the positional relationship thereof.
Claim 24
Dependent Claim
181 words
A focus detection system for detecting a focus state of an object lens, comprising: optical means for forming first and second light distributions respectively corresponding to first and second images having light reflective fluxes passing through the different parts of the object lens, whereby the positional relationship between said first and second light distributions varies in accordance with the focus state of the object lens; first and second sensing means for sensing said first and second light distributions said first and second sensing means respectively including a sensing area constituted by a plurality of sensor elements and including a plurality of sensing sub-areas, said sub-areas being narrower than said sensing area and not overlapping each other; and signal processing means for performing a first correlational calculation on the basis of the signals from the sensor elements in said sensing area and for performing a second correlational calculation on the basis of the signals from the sensor elements in said sub-areas, said second correlational calculation being executed when an evaluation of the signals from sensing area does not satisfy a predetermined condition.
Claim 25
Dependent Claim
181 words
A focus detection system for detecting a focus state of an object lens, comprising: optical means for forming first and second light distributions respectively corresponding to first and second images having light reflective fluxes passing through the different parts of the object lens, whereby the positional relationship between said first and second light distributions varies in accordance with the focus state of the object lens; first and second sensing means for sensing said first and second light distributions said first and second sensing means respectively including a sensing area constituted by a plurality of sensor elements and including a plurality of sensing sub-areas, said sub-areas being narrower than said sensing area and not overlapping each other; and signal processing means for performing a first correlational calculation on the basis of the signals from the sensor elements in said sensing area and for performing a second correlational calculation on the basis of the signals from the sensor elements in said sub-areas, said second correlational calculation being executed when an evaluation of the signals from sensing area does not satisfy a predetermined condition.
Claim 26
Dependent Claim
32 words
A focus detection system according to claim 19, wherein of said sub-areas is previously selected and the second correlational calculation on the basis of the selected sub-area is adopted as a result.
Claim 27
Dependent Claim
28 words
A focus detection system according to claim 19, wherein one of the second correlation calculation results on the basis of said sub-areas is adopted by evaluating the results.
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