US5677733A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure control device having a plurality of light detecting areas
Assignee: Canon Inc
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Filing: 1994-02-01
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Granted: 1997-10-14
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Expires: 2014-02-01
Abstract
Abstract An exposure control device having a light measuring area setting circuit which sets a light measuring area on an image sensing plane, a discriminating circuit which discriminates from each other varied states of the image sensing plane through video signal parts corresponding to the inside and the outside of the light measuring area and an exposure compensating circuit which compensates the state of exposure to light is arranged to shift the set position of the light measuring area to trace an object's image at least when the exposure compensating circuit is in operation. The operating modes of the device includes a first light measuring mode in which a quantity of light is measured on the basis of the average video signal level of the whole image sensing plane, a second light measuring mode in which the light quantity is measured with weight attached to a video signal part obtained from the inside of the light measuring area, and a third light measuring mode in which the light quantity is measured with weight attached to the video signal of the light measuring area by shifting the light measuring area to trace the object. The three light measuring modes are adaptively switched from one over to another.
Inventors
- 👤 Katsuji Yoshimura
- 👤 Kitahiro Kaneda
- 👤 Hideo Homma
- 👤 Kunihiko Yamada
- 👤 Hirofumi Suda
- 👤 Akihiro Fujiwara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:37
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/70; H04N23/71
Claims Analysis
Total Claims: 52
Claim 1
Independent Claim
170 words
An automatic exposure control device comprising: a) light measuring area setting means for setting a light measuring area to a set position in a part of an image sensing plane, said light measuring area setting means further processing image signal levels corresponding to the inside and the outside of said light measuring area; b) discriminating means for discriminating a state of said image sensing plane on the basis of the processed image signal levels; c) exposure compensating means for making compensation for exposure conditions on the basis of a result of discrimination made by said discriminating means; d) object tracing means operable also on the basis of a result of discrimination by said discriminating means for causing displacement of the set position of said light measuring area to trace an object to be photographed at least for a period during which said exposure compensating means is in operation; and e) inhibiting means for inhibiting an operation of said object tracing means on the basis of the result of the discrimination.
Claim 2
Dependent Claim
170 words
An automatic exposure control device comprising: a) light measuring area setting means for setting a light measuring area to a set position in a part of an image sensing plane, said light measuring area setting means further processing image signal levels corresponding to the inside and the outside of said light measuring area; b) discriminating means for discriminating a state of said image sensing plane on the basis of the processed image signal levels; c) exposure compensating means for making compensation for exposure conditions on the basis of a result of discrimination made by said discriminating means; d) object tracing means operable also on the basis of a result of discrimination by said discriminating means for causing displacement of the set position of said light measuring area to trace an object to be photographed at least for a period during which said exposure compensating means is in operation; and e) inhibiting means for inhibiting an operation of said object tracing means on the basis of the result of the discrimination.
Claim 3
Dependent Claim
52 words
A device according to claim 1, wherein said light measuring area setting means processes said image signal levels to obtain a difference between average signal levels inside and outside of said light measuring area and wherein said discriminating means is responsive to said difference to control operation of said exposure compensating means.
Claim 4
Dependent Claim
56 words
A device according to claim 1, wherein said exposure compensating means is operable in a back-lighting compensating mode, a wash-out compensating mode or an average light measuring mode and is arranged to select one of said modes as the operating mode of said exposure compensation means on the basis of an output of said discriminating means.
Claim 5
Dependent Claim
73 words
A device according to claim 3, wherein said light measuring area setting means computes an average signal level of the inside of said light measuring area and an average signal level of the outside of said light measuring area and obtains the difference between said levels and wherein said discriminating means result causes operation of said exposure compensating means in said wash-out compensating mode when said difference is less than a predetermined value.
Claim 6
Dependent Claim
73 words
A device according to claim 3, wherein said light measuring area setting means computes an average signal level of the inside of said light measuring area and an average signal level of the outside of said light measuring area and obtains the difference between said levels and wherein said discriminating means result causes operation of said exposure compensating means in said back-lighting compensating mode when said difference is greater than a predetermined value.
Claim 7
Dependent Claim
87 words
A device according to claim 3, wherein said light measuring area setting means computes an average signal level of the inside of said light measuring area and an average signal level of the outside of said light measuring area and obtains the difference between said levels and wherein said. discriminating means result causes operation of said exposure compensating means in said average light measuring mode when said difference is greater than or equal to one predetermined value and less than or equal to a second predetermined value.
Claim 8
Dependent Claim
119 words
A device according to claim 3, wherein said light measuring area setting means computes an average signal level of the inside of said light measuring area and an average signal level of the outside of said light measuring area and obtains the difference between said levels and wherein said discriminating means result causes operation of said exposure compensating means in said wash-out compensating mode when said difference is less than a first predetermined value, in said back-lighting compensating mode when said difference is greater than a second predetermined value, and in said average light measuring mode when said difference is greater than or equal to said first predetermined value and less than or equal to said second predetermined value.
Claim 9
Dependent Claim
26 words
A device according to claim 1, wherein said exposure compensating means makes exposure compensation by varying degrees of weight to be attached to said image signals.
Claim 10
Dependent Claim
30 words
A device according to claim 2, wherein said object tracing means is operable to shift a position of said light measuring area in a direction in which said difference increases.
Claim 11
Independent Claim
66 words
A device according to claims 5, 6, or 9, wherein said object tracing means is arranged to cause said light measuring area to trace the object seized within said light measuring area when said difference in said average signal levels between the inside and the outside of said light measuring area is determined by said discriminating means to have a prescribed relation to a preselected value.
Claim 12
Independent Claim
114 words
A device according to claims 5, 6, or 9, wherein said object tracing means is arranged to cause said light measuring area to trace the object seized within said light measuring area when said difference in said average signal levels between the inside and the outside of said light measuring area is determined by said discriminating means to have a prescribed relation to a preselected value and is further operative to bring an object tracing action to a stop when said difference in said average signal levels between the inside and the outside of said light measuring area is determined by said discriminating means not to have said prescribed relation to said preselected value.
Claim 13
Dependent Claim
171 words
An automatic exposure control device comprising: a) light measuring area setting means for setting a light measuring area to a set position in a part of an image sensing plane; b) light measuring means for detecting image signals and average signal levels of said image signals from said image sensing plane which respectively correspond to the inside and the outside of said light measuring area; c) computing means for computing said average signal levels to discriminate an exposure condition and for outputting a control signal for use in controlling an iris of a photo-taking optical system; d) compensating means for compensating the control signal by varying degrees of weight to be attached to said image signals according to the exposure condition; e) object tracing means for operable shifting said light measuring area on said image sensing plane from said set position to other positions to trace an object to be photographed; and f) control means for controlling inhibit an operation of said object tracing means on the basis of the exposure-condition.
Claim 14
Dependent Claim
171 words
An automatic exposure control device comprising: a) light measuring area setting means for setting a light measuring area to a set position in a part of an image sensing plane; b) light measuring means for detecting image signals and average signal levels of said image signals from said image sensing plane which respectively correspond to the inside and the outside of said light measuring area; c) computing means for computing said average signal levels to discriminate an exposure condition and for outputting a control signal for use in controlling an iris of a photo-taking optical system; d) compensating means for compensating the control signal by varying degrees of weight to be attached to said image signals according to the exposure condition; e) object tracing means for operable shifting said light measuring area on said image sensing plane from said set position to other positions to trace an object to be photographed; and f) control means for controlling inhibit an operation of said object tracing means on the basis of the exposure-condition.
Claim 15
Dependent Claim
41 words
A device according to claim 12, wherein said image signals are video signals and wherein said light measuring means is operative to detect average luminance signal levels which respectively correspond to the inside and the outside of said light measuring area.
Claim 16
Dependent Claim
32 words
A device according to claim 12, wherein said compensating means is arranged to add together said image signals by attaching respective predetermined of said degrees of said weight to said image signals.
Claim 17
Dependent Claim
31 words
A device according to claim 14, wherein said computing means computes said difference between said average signal levels and provides said computing means control signal on the basis of said difference.
Claim 18
Dependent Claim
83 words
A device according to claim 15, further including an iris controller and wherein said compensating means provides an iris controller input signal by increasing the degree of weight to be attached to the image signal corresponding to the inside of said light measuring area when said computing means determines said difference to indicate that the average signal level inside of said light measuring area is greater than the average signal level outside of said light measuring area by less than one predetermined value.
Claim 19
Dependent Claim
79 words
A device according to claim 16, wherein said compensating means provides said iris controller input signal by increasing the degree of weight to be attached to the image signal corresponding to the inside of said light measuring area when said computing means determines said difference to indicate that the average signal level outside of said light measuring area is greater than the average signal level inside of said light measuring area by not less than a second predetermined value.
Claim 20
Dependent Claim
60 words
A device according to claim 12, wherein said compensating means has a back-lighting compensating mode and selects said back-lighting compensating mode when said computing means determines said difference to indicate that the average signal level inside of said light measuring area is greater than the average signal level outside of said light measuring area by less than one predetermined value.
Claim 21
Dependent Claim
74 words
A device according to claim 18, wherein said compensating means further has a wash-out compensating mode and selects said wash-out compensating mode when said computing means determines said difference to indicate that the average signal level outside of said light measuring area is greater than the average signal level inside of said light measuring area by not less than a second predetermined value, said second predetermined value being larger than said one predetermined value.
Claim 22
Dependent Claim
78 words
A device according to claim 12, wherein said compensating means has an average light measuring mode wherein said image signals are used without weighting of either thereof, said compensating means selecting said average light measuring mode when said computing means determines said difference to indicate that the average signal level inside of said light measuring area is greater than the average signal outside of said light measuring area by an amount equal to or exceeding one predetermined value.
Claim 23
Dependent Claim
72 words
A device according to claim 20, wherein said compensating means selects said average light measuring mode when said computing means determines said difference to indicate that the average signal level inside of said light measuring area to be greater than the average signal outside of said light measuring area by an amount equal to or less than a second predetermined value, said second predetermined value being larger than said one predetermined value.
Claim 24
Dependent Claim
45 words
A device according to claim 12, wherein said control means causes said object tracing means to shift said light measuring area in a direction according to which said difference in average signal level between the inside and the outside of said light measuring area increases.
Claim 25
Dependent Claim
57 words
A device according to claim 22, wherein said control means is arranged to operate said object tracing means when said computing means determines said difference to indicate that the average signal inside of said light measuring area is greater than the average signal level outside of said light measuring area by not less than one predetermined value.
Claim 26
Dependent Claim
70 words
A device according to claim 23, wherein said control means is arranged to operate said object tracing means when said computing means determines said difference to indicate that the average signal level inside of said light measuring area is greater than the average signal level outside of said light measuring area by not less than a second predetermined value, said second predetermined value being larger than said one predetermined value.
Claim 27
Dependent Claim
229 words
An exposure control device comprising: a) image sensing means for converting into an image signal an image of an object formed on an image sensing plane by a photo taking-optical system to output said image signal; b) area setting means for setting a light measuring area of said image sensing plane and for shifting said light measuring area from the set position to different positions on said image sensing plane; c) light measuring means for detecting image signal levels inside and outside of said light measuring area and discriminating a condition of a light distribution in said image sensing plane; d) exposure control means having a plurality of operating modes which exposure control characteristics are different from each other for controlling exposure on said image sensing plane for said object image; and e) control means responsive to said image signal levels detected by said light measuring means for controlling said area setting means to shift said light measuring area in such a way as to increase a difference between image signal levels corresponding to the inside and the outside of said light measuring area respectively and for selecting an operating mode of said exposure control means, said control means adaptively determining a feature of the object to be traced by said light measuring area on the basis of the condition of light distribution discriminated by said light measuring means.
Claim 28
Dependent Claim
229 words
An exposure control device comprising: a) image sensing means for converting into an image signal an image of an object formed on an image sensing plane by a photo taking-optical system to output said image signal; b) area setting means for setting a light measuring area of said image sensing plane and for shifting said light measuring area from the set position to different positions on said image sensing plane; c) light measuring means for detecting image signal levels inside and outside of said light measuring area and discriminating a condition of a light distribution in said image sensing plane; d) exposure control means having a plurality of operating modes which exposure control characteristics are different from each other for controlling exposure on said image sensing plane for said object image; and e) control means responsive to said image signal levels detected by said light measuring means for controlling said area setting means to shift said light measuring area in such a way as to increase a difference between image signal levels corresponding to the inside and the outside of said light measuring area respectively and for selecting an operating mode of said exposure control means, said control means adaptively determining a feature of the object to be traced by said light measuring area on the basis of the condition of light distribution discriminated by said light measuring means.
Claim 29
Dependent Claim
93 words
A device according to claim 25, wherein said plurality of light measuring modes includes an average light measuring mode in which exposure of said image sensing plane is controlled by said exposure control means on the basis of an average image signal level obtained from the whole of said image sensing plane and a weighted light measuring mode in which exposure control is performed by said exposure control means on the basis of a weighting of an image signal obtained from the inside of said light measuring area in said set position thereof.
Claim 30
Dependent Claim
78 words
A device according to claim 26, wherein said control means is operative to select said average light measuring mode with said light measuring area set in a fixed position on said image sensing plane, to select said weighted light measuring mode with said light measuring area set in a fixed position on said image sensing plane, or to select said weighted light measuring mode with said light measuring area moved to a position other than a fixed position.
Claim 31
Dependent Claim
87 words
A device according to claim 27, wherein said control means includes difference circuit means for providing indication of a difference between video signal levels inside and the outside of said light measuring area, and selects said weighted light measuring mode when said difference is less than a first threshold value or greater than a second threshold value and selects said average light measuring mode when said difference is equal to or greater than said first threshold value or equal to or less than said second threshold value.
Claim 32
Dependent Claim
178 words
An automatic exposure control device comprising: (a) light measuring area setting means for setting a plurality of light measuring areas on an image sensing plane; (b) detecting means for detecting image signal levels corresponding to said light measuring areas, respectively; and (c) exposure control means arranged to discriminate a state of the image sensing plane on the basis of a result of processing of the image signal levels of the respective light measuring areas detected by said detecting means and to select and execute an optimum one of a plurality of exposure control modes in response to a result of the discrimination, wherein said plurality of exposure control modes includes a first mode for detecting a change of an object on said image sensing plane on the basis of an output of said detecting means and to shift positions occupied by said light measuring areas on said image sensing plane and a second mode for inhibiting the operation of the first mode and fixedly setting said light measuring areas at predetermined positions respectively on said image sensing plane.
Claim 33
Dependent Claim
178 words
An automatic exposure control device comprising: (a) light measuring area setting means for setting a plurality of light measuring areas on an image sensing plane; (b) detecting means for detecting image signal levels corresponding to said light measuring areas, respectively; and (c) exposure control means arranged to discriminate a state of the image sensing plane on the basis of a result of processing of the image signal levels of the respective light measuring areas detected by said detecting means and to select and execute an optimum one of a plurality of exposure control modes in response to a result of the discrimination, wherein said plurality of exposure control modes includes a first mode for detecting a change of an object on said image sensing plane on the basis of an output of said detecting means and to shift positions occupied by said light measuring areas on said image sensing plane and a second mode for inhibiting the operation of the first mode and fixedly setting said light measuring areas at predetermined positions respectively on said image sensing plane.
Claim 34
Dependent Claim
41 words
A device according to claim 29, wherein said light measuring area setting means sets a light measuring frame on said image sensing plane and said plurality of light measuring areas are an inside area and an outside area of said frame.
Claim 35
Dependent Claim
36 words
A device according to claim 30, wherein said exposure control means discriminates the state of the image sensing plane on the basis of the difference of signal levels corresponding to inside and outside of said frame.
Claim 36
Dependent Claim
54 words
A device according to claim 30, wherein said exposure control means is operable in a back-lighting compensating mode, a wash-out compensating mode, or an average light measuring mode and selects one of said modes as the operating mode of said exposure control means on the basis of the state of the image sensing plane.
Claim 37
Dependent Claim
47 words
A device according to claim 31, wherein said exposure control means detects a change of an object on said image sensing plane on the basis of said difference and controls a position of said light measuring area on said image sensing plane so that said difference increases.
Claim 38
Dependent Claim
167 words
An automatic exposure control device comprising: a) area setting means for setting a plurality of light measuring areas on an image sensing plane; b) light measuring means for detecting signal levels of image signals respectively corresponding to said plurality of said light measuring areas; c) computing means for computing said signal levels to output a control signal for controlling an exposure state of image sensing plane and for discriminating a condition of light distribution on said image sensing plane; d) compensating means for compensating the operation of said computing means by varying degrees of weight to be attached to said image signals; e) shifting means for changing the set position of said light measuring area on said image sensing plane according to a movement of an object to be photographed; and f) control means responsive to said light measuring means for controlling operations of said compensating means and said shifting means and controlling and prohibiting operation of said shifting means according to the condition of light distribution.
Claim 39
Dependent Claim
167 words
An automatic exposure control device comprising: a) area setting means for setting a plurality of light measuring areas on an image sensing plane; b) light measuring means for detecting signal levels of image signals respectively corresponding to said plurality of said light measuring areas; c) computing means for computing said signal levels to output a control signal for controlling an exposure state of image sensing plane and for discriminating a condition of light distribution on said image sensing plane; d) compensating means for compensating the operation of said computing means by varying degrees of weight to be attached to said image signals; e) shifting means for changing the set position of said light measuring area on said image sensing plane according to a movement of an object to be photographed; and f) control means responsive to said light measuring means for controlling operations of said compensating means and said shifting means and controlling and prohibiting operation of said shifting means according to the condition of light distribution.
Claim 40
Dependent Claim
52 words
A device according to claim 34, wherein said compensating means is operable in a back-lighting compensating mode, a wash-out compensating mode or an average light measuring mode and selects one of said modes as the operating mode of said compensation means on the basis of an output of said light measuring means.
Claim 41
Dependent Claim
157 words
A device according to claim 34, wherein said plurality of light measuring areas include an inside area and an outside area of the light measuring frame set on the image sensing plane, and said compensating means is arranged to set a normal-lighting compensating mode when the average luminance level at the inside of said light measuring frame is higher than the average luminance level at the outside of said light measuring frame by a predetermined value, to set a back-lighting compensating mode when the average luminance level at the outside of said light measuring frame is higher than the average luminance level at the inside of said light measuring frame by a predetermined value, and to set an average light measuring mode when a difference between the average luminance level at the inside of said light measuring frame and the average luminance level at the outside of said light measuring frame is lower than the predetermined value.
Claim 42
Dependent Claim
85 words
A device according to claim 34, wherein said compensating means is capable to set an object tracing mode for shifting said light measuring frame in response to an object when the difference between the average luminance level at the inside of said light measuring frame and the average luminance level at the outside of said light measuring frame is equal to or higher than the predetermined value and said compensating means prohibits the object tracing mode when said difference is lower than the predetermined value.
Claim 43
Dependent Claim
190 words
An image sensing device comprising: a) image sensing means for converting an image formed on an image sensing plane to an image signal; b) setting means for setting a plurality of detecting areas on said image sensing plane; c) detecting means for detecting image signals output from said image sensing means respectively corresponding to said plurality of detecting areas; d) computing means for computing said image signals to output a control signal for controlling an image sensing operation; e) compensating means for compensating the operation of said computing means by varying degrees of weight to be attached to said image signals corresponding to said plurality of detecting areas; f) shifting means for operable changing the set position of said detecting areas on said image sensing plane according to a variation of the image on said image sensing plane; and g) control means responsive to said detecting means for controlling operation of said compensating means and said shifting means, said control means including a mode of operating the compensating means while operating said shifting means and another mode of operating said compensating means while inhibiting the operation of said shifting means.
Claim 44
Dependent Claim
190 words
An image sensing device comprising: a) image sensing means for converting an image formed on an image sensing plane to an image signal; b) setting means for setting a plurality of detecting areas on said image sensing plane; c) detecting means for detecting image signals output from said image sensing means respectively corresponding to said plurality of detecting areas; d) computing means for computing said image signals to output a control signal for controlling an image sensing operation; e) compensating means for compensating the operation of said computing means by varying degrees of weight to be attached to said image signals corresponding to said plurality of detecting areas; f) shifting means for operable changing the set position of said detecting areas on said image sensing plane according to a variation of the image on said image sensing plane; and g) control means responsive to said detecting means for controlling operation of said compensating means and said shifting means, said control means including a mode of operating the compensating means while operating said shifting means and another mode of operating said compensating means while inhibiting the operation of said shifting means.
Claim 45
Dependent Claim
55 words
An apparatus according to claim 38, wherein the detecting areas include areas at the inside and the outside of one detecting frame and said shifting means is arranged to shift: said detecting frame in such direction that the difference of the luminance level between the outside and the inside of said detecting frame is increased.
Claim 46
Dependent Claim
47 words
An apparatus according to claim 38, wherein said compensating means is exposure compensating means, and said control means includes a mode of operating the compensating means while operating said shifting means and another mode of operating said compensating means while holding said shifting means in not-operating state.
Claim 47
Dependent Claim
118 words
An automatic exposure control device, comprising: a) area setting means for setting a predetermined detecting area on an image sensing plane; b) exposure control means for controlling an exposure on the basis of a luminance level of an image signal corresponding to the predetermined area on said image sensing plane; and c) area control means having a first mode in which said area changes so as to follow a low luminance portion on said image sensing plane and a second mode in which said area changes so as to follow a high luminance portion on said image sensing plane and selecting said first and second mode on the basis of a luminance condition on the image sensing plane.
Claim 48
Dependent Claim
118 words
An automatic exposure control device, comprising: a) area setting means for setting a predetermined detecting area on an image sensing plane; b) exposure control means for controlling an exposure on the basis of a luminance level of an image signal corresponding to the predetermined area on said image sensing plane; and c) area control means having a first mode in which said area changes so as to follow a low luminance portion on said image sensing plane and a second mode in which said area changes so as to follow a high luminance portion on said image sensing plane and selecting said first and second mode on the basis of a luminance condition on the image sensing plane.
Claim 49
Dependent Claim
40 words
A device according to claim 41, wherein said area control means is arranged to change over said first mode and said second mode in response to a difference of luminance level between the inside and the outside of said area.
Claim 50
Dependent Claim
62 words
A device according to claim 41, wherein said area control means is arranged to set a third mode in which said area is set at a substantially central predetermined position in said image sensing plane and the change thereof is prohibited when the difference of luminance level between the inside and the outside of said area is lower than a predetermined value.
Claim 51
Dependent Claim
45 words
A device according to claim 43, wherein said exposure control means is arranged to effect a center weighted light measuring operating when said first mode or said second mode is selected and to effect an average light measuring operation when said third mode is selected.
Claim 52
Dependent Claim
34 words
A device according to claim 43, wherein said exposure control means is capable of effecting a back-lighting compensation when said first mode is selected and a wash-out compensation when said second mode is selected.
References Cited (Backward Citations)
US4382665A
Cited
US4550995A
Cited
US4644397A
Cited
US4774401A
Cited
US4792820A
Cited
US4713533A
Cited
US4868871A
Cited
US5272538A
Cited
US5023712A
Cited
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