Patent US5339163A successfully refreshed from Google Patents.
US5339163A
Expired / Lapsed
US
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Automatic exposure control device using plural image plane detection areas
Assignee: Canon Inc
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Filing: 1992-04-09
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Granted: 1994-08-16
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Expires: 2012-04-09
Abstract
Abstract An exposure control device includes an area setting circuit which sets a light measuring area on a part of an image sensing plane; a judging circuit which detects a back light image plane on the basis of a difference in level between video signals corresponding to the inside and the outside of the light measuring area; a high luminance detecting circuit which detects a high luminance part of the image sensing plane on the basis of the video signals; and a control circuit arranged to have the light measuring area set on the image sensing plane excluding the high luminance part from the light measuring area by controlling the area setting circuit on the basis of the output of the high luminance detection circuit when the image sensing plane is judged to be a back light image plane by the judging circuit. The device is arranged to attach weight to the average levels of the signals of the inside and the outside of the light measuring area according to the result of comparison of these signals, to add the weighted average signal levels together and to perform exposure control according to the result of addition.
Inventors
- 👤 Hideo Homma
- 👤 Kitahiro Kaneda
- 👤 Kunihiko Yamada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:49
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/70; H04N23/72; H04N23/71
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
187 words
A light measuring device comprising: a) image sensing means for sensing an image formed on an image sensing plane and outputting image signals corresponding to a sensed image; b) area setting means for setting a predetermined detection area on a part of said image sensing plane; c) light measuring means for measuring light on the basis of levels of the image corresponding to the inside and the outside of said detection area, respectively; d) judging means for judging a lighting condition of said second image sensing plane on the basis of an output of said light measuring means; and e) control means for automatically determining degrees of weighting the image signals output by said image sensing means corresponding to the inside and the outside of said detection area, respectively, in accordance with an output of said judging means; attaching predetermined weights to signal levels of said image signals corresponding to the inside and the outside of said detection area on the basis of the determined degree of weighting, and performing exposure control action on the basis of an exposure control signal obtained by adding the weighted signals.
Claim 2
Dependent Claim
187 words
A light measuring device comprising: a) image sensing means for sensing an image formed on an image sensing plane and outputting image signals corresponding to a sensed image; b) area setting means for setting a predetermined detection area on a part of said image sensing plane; c) light measuring means for measuring light on the basis of levels of the image corresponding to the inside and the outside of said detection area, respectively; d) judging means for judging a lighting condition of said second image sensing plane on the basis of an output of said light measuring means; and e) control means for automatically determining degrees of weighting the image signals output by said image sensing means corresponding to the inside and the outside of said detection area, respectively, in accordance with an output of said judging means; attaching predetermined weights to signal levels of said image signals corresponding to the inside and the outside of said detection area on the basis of the determined degree of weighting, and performing exposure control action on the basis of an exposure control signal obtained by adding the weighted signals.
Claim 3
Dependent Claim
20 words
A device according to claim 1, wherein said control means includes exposure control means for performing said exposure control action.
Claim 4
Dependent Claim
47 words
A device according to claim 2, wherein said exposure control means includes iris means for controlling a quantity of light incident on said image sensing means and is arranged to keep a level of said image signal constant by controlling an aperture area of said iris means.
Claim 5
Dependent Claim
22 words
A device according to claim 3, further comprising an automatic gain control (AGC) circuit for controlling a gain of said image signal.
Claim 6
Dependent Claim
33 words
A device according to claim 1, wherein said control means attaches the predetermined weights to average signal levels of said image signals corresponding to the inside and the outside of said detection area.
Claim 7
Dependent Claim
48 words
A device according to claim 5, wherein said judging means is arranged to judge whether or not said image sensing plane is a back lighted image plane on the basis of a difference between the average signal levels of the inside and the outside of said detection area.
Claim 8
Dependent Claim
58 words
A device according to claim 6, wherein said judging means is arranged to judge said image sensing plane to be said back lighted image plane when the average signal level of the outside of said detection area is greater than the average signal level of the inside of said detection area by not less than a predetermined value.
Claim 9
Dependent Claim
46 words
A device according to claim 7, wherein said control means is arranged to increase the weight attached to the image signal of the inside of said detection area when said image sensing plane is judged to be said back lighted image plane by said judging means.
Claim 10
Dependent Claim
43 words
A device according to claim 5, wherein said judging means is arranged to judge in a plurality of steps a difference between average signal levels of the inside and the outside of said detection area in accordance with a plurality of threshold values.
Claim 11
Dependent Claim
52 words
A device according to claim 9, wherein said control means is arranged to vary in a plurality of steps degrees of weight to be attached to said image signals of the inside and the outside of said detection area on the basis of a result of judgment made by said judging means.
Claim 12
Dependent Claim
59 words
A device according to claim 10, wherein said control means is arranged to increase the weight to be attached to the image signal of the inside of said detection area according to an increase of said difference by which the average signal level of the outside of said detection area exceeds that of the inside of said detection area.
Claim 13
Dependent Claim
81 words
A device according to claim 5, wherein said light measuring means includes a gate circuit for separating the image signals of the inside and the outside of said detection area from each other, low-pass filters for averaging the image signals of the inside and the outside of said detection area respectively as said averaging circuits, and said judging means includes a comparator for judging said condition of said image sensing plane on the basis of comparing outputs of said low-pass filters.
Claim 14
Dependent Claim
84 words
A device according to claim 5, wherein said light measuring means includes low-pass filters for respectively obtaining average signal levels of image signals corresponding to the inside and the outside of said detection area, and wherein said control means includes impedance elements for attaching weight to each of outputs of said low-pass filters, and switch means for switching said low-pass filters from one to the other or for varying degrees of weight to be attached to each of the outputs of said low-pass filters.
Claim 15
Dependent Claim
144 words
An exposure control device comprising: a) area setting means for setting a predetermined detection area on an image sensing plane of an image sensing device converting an image formed on said image sensing plane into an image signal; b) exposure control means for controlling an exposing condition on said image sensing plane on the basis of an output obtained by multiplying signal levelxs of image signals corresponding to the inside and the outside of said detection area by predetermined coefficients for attaching predetermined weights; c) judging means for judging a condition of said image sensing plane on the basis of levels of the image signals corresponding to the inside and the outside of said detection area; and d) compensating means for compensating the operation of said exposure control means by varying said predetermined coefficients on the basis of an output of said judging means.
Claim 16
Dependent Claim
144 words
An exposure control device comprising: a) area setting means for setting a predetermined detection area on an image sensing plane of an image sensing device converting an image formed on said image sensing plane into an image signal; b) exposure control means for controlling an exposing condition on said image sensing plane on the basis of an output obtained by multiplying signal levelxs of image signals corresponding to the inside and the outside of said detection area by predetermined coefficients for attaching predetermined weights; c) judging means for judging a condition of said image sensing plane on the basis of levels of the image signals corresponding to the inside and the outside of said detection area; and d) compensating means for compensating the operation of said exposure control means by varying said predetermined coefficients on the basis of an output of said judging means.
Claim 17
Dependent Claim
47 words
A device according to claim 14, wherein said exposure control means includes iris means for controlling a quantity of light incident on said image sensing plane and is arranged to keep a level of said image signal constant by controlling an aperture area of said iris means.
Claim 18
Dependent Claim
22 words
A device according to claim 14, further comprising an automatic gain control (AGC) circuit for controlling a gain of said image signal.
Claim 19
Dependent Claim
45 words
A device according to claim 14, wherein said exposure control means controls the exposing condition on the basis of an output obtained by multiplying average signal levels of image signals corresponding to the inside and the outside of said detection area by said predetermined coefficients.
Claim 20
Dependent Claim
47 words
A device according to claim 17, wherein said judging means is arranged to judge whether or not said image sensing plane is a back lighted image plane on the basis of a difference between said average levels of the inside and the outside of said detection area.
Claim 21
Dependent Claim
103 words
A device according to claim 18, wherein said judging means is arranged to judge said image sensing plane to be said back lighted image plane when the average signal level of the outside of said detection area is greater than that of the inside of said detection area by not less than a predetermined value, and wherein said compensating means is arranged to increase a weight to be attached to the image signal of the inside of said detection area by varying a coefficient when said image sensing plane is judged to be in said back lighted image plane by said judging means.
Claim 22
Dependent Claim
46 words
A device according to claim 19, wherein said means is arranged to judge in a plurality of steps a difference between average signal levels of the outside of said detection area and the inside of said detection area in accordance with a plurality of threshold areas.
Claim 23
Dependent Claim
52 words
A device according to claim 20, wherein said compensating means in arranged to vary in a plurality of steps of said coefficients to be attached to said image signals of the inside and the outside of said detection area on the basis of a result of judgment made by said judging means.
Claim 24
Dependent Claim
59 words
A device according to claim 21, wherein said compensating means is arranged to increase the weight to be attached to the image signal of the inside of said detection area according to an increase of a value by which the average signal level of the outside of said detection area exceeds that of the inside of said detection area.
Claim 25
Dependent Claim
74 words
A device according to claim 14 or 20, wherein said exposure control means includes a gate circuit for separating the image signals of the inside and the outside of said detection area from each other, low-pass filters for averaging the image signals of the inside and the outside of said detection area respectively, and a comparator for judging said condition of said image sensing plane on the basis of outputs of said low-pass filters.
Claim 26
Dependent Claim
79 words
A device according to claim 14 or 20, wherein said exposure control means includes low-pass filters for respectively obtaining average signal levels of image signals corresponding to the inside and the outside of said detection area, impedance elements for varying said coefficients for outputs of said low-pass filters, and switch means for switching said low-pass filters from one to the other or for varying degrees of weight to be attached to each of the outputs of said low-pass filters.
Claim 27
Dependent Claim
161 words
A video camera comprising: a) image sensing means for outputting an image signal corresponding to a sensed image formed on an image sensing plane; b) area setting means for setting a predetermined detection area on said image sensing plane of said image sensing means; c) exposure control means for controlling a quantity of light incident on said image sensing means and/or a gain of a circuit which processes the image signal, on the basis of image signals corresponding to the inside and the outside of said detection area to which respective predetermined weights are attached; d) judging means for judging a condition of said image sensing plane on the basis of levels of said image signals corresponding to the inside and the outside of said detection area; and e) compensating means for compensating the operation of said exposure control means by varying said predetermined weights attached to said image signals corresponding to the inside and the outside of said detection area.
Claim 28
Dependent Claim
161 words
A video camera comprising: a) image sensing means for outputting an image signal corresponding to a sensed image formed on an image sensing plane; b) area setting means for setting a predetermined detection area on said image sensing plane of said image sensing means; c) exposure control means for controlling a quantity of light incident on said image sensing means and/or a gain of a circuit which processes the image signal, on the basis of image signals corresponding to the inside and the outside of said detection area to which respective predetermined weights are attached; d) judging means for judging a condition of said image sensing plane on the basis of levels of said image signals corresponding to the inside and the outside of said detection area; and e) compensating means for compensating the operation of said exposure control means by varying said predetermined weights attached to said image signals corresponding to the inside and the outside of said detection area.
Claim 29
Dependent Claim
44 words
A device according to claim 25, wherein said exposure control means controls the exposure condition on the basis of an output obtained by attaching said predetermined weights to levels of the image signals corresponding to the inside and the outside of said detection area.
Claim 30
Dependent Claim
71 words
A device according to claim 25, wherein said judging means is arranged to compare levels of the image signals corresponding to the inside and outside of said detecting area, to judge whether the image on the image sensing plane is a backlight image or not, and to increase the weighting of the level in said detecting area when the image on the image sensing plane is judged as a backlight image.
Claim 31
Dependent Claim
18 words
A device according to claim 25, wherein said attaching of weights is effected in a plurality of stages.
Claim 32
Dependent Claim
155 words
A video camera comprising: a) image sensing means for outputting an image signal corresponding to a sensed image formed on an image sensing plane; b) an iris for varying a quantity of light incident on said image sensing plane; c) area setting means for setting a plurality of detection areas on said image sensing plane of said image sensing means; d) discriminating means for discriminating a distribution of a light condition on the image sensing plane on the basis of levels of the image signals corresponding to the plurality of the detection areas; e) exposure control means for controlling said iris on the basis of an output obtained by multiplying signal levels of the image signals corresponding to the plurality of the detection areas by predetermined coefficients; and f) compensating means for compensating the operation of said exposure control means by varying said predetermined coefficients on the basis of an output of said discriminating means.
Claim 33
Dependent Claim
155 words
A video camera comprising: a) image sensing means for outputting an image signal corresponding to a sensed image formed on an image sensing plane; b) an iris for varying a quantity of light incident on said image sensing plane; c) area setting means for setting a plurality of detection areas on said image sensing plane of said image sensing means; d) discriminating means for discriminating a distribution of a light condition on the image sensing plane on the basis of levels of the image signals corresponding to the plurality of the detection areas; e) exposure control means for controlling said iris on the basis of an output obtained by multiplying signal levels of the image signals corresponding to the plurality of the detection areas by predetermined coefficients; and f) compensating means for compensating the operation of said exposure control means by varying said predetermined coefficients on the basis of an output of said discriminating means.
Claim 34
Dependent Claim
42 words
A camera device according to claim 29, wherein said exposure control means controls said iris on the basis of an output obtained by multiplying average signal levels of the images corresponding to the plurality of the detection areas by said predetermined coefficients.
Claim 35
Dependent Claim
61 words
A device according to claim 29, wherein said discriminating means is arranged to compare the average signal levels of said respective image signals, to judge whether the image on the image sensing plane is a backlight image or not, and to increase the weighting on the signal level in said detecting area when the image is judged as a backlight image.
Claim 36
Dependent Claim
20 words
A device according to claim 30, wherein said multiplying by said predetermined coefficients is effected in a plurality of stages.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-08-15 | 1998-02-14 | 1998-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-15 | 2002-02-14 | 2002-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-15 | 2006-02-14 | 2006-08-16 | $7700.00 | Window Closed / Lapsed |