Patent EP0605240A2 successfully refreshed from Google Patents.
EP0605240A2
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EP
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Automatic focusing apparatus
Assignee: Canon Inc
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Filing: 1993-12-24
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Granted: —
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Expires: 2013-12-24
Abstract
Abstract There is disclosed an integrated circuit for focus control, which is obtained by integrating, on a single chip, a filter circuit for extracting a predetermined signal component, which changes in accordance with a focusing state, from an image pickup signal, a gate circuit for extracting a focus signal, corresponding to a portion in a focus detection region in a photographing frame, from a focus signal extracted by the filter circuit, an arithmetic circuit for generating an evaluation signal of the focusing state by performing predetermined signal processing for the focus signal extracted by the gate circuit and corresponding to the portion in the focus detection region, a region setting circuit for controlling the positions or the number of focus detection regions in the photographing field by controlling the gate circuit, and an interface for connecting the respective circuits to an external circuit, and allowing the circuits to be controlled by a command from the control circuit.
Inventors
- 👤 Ryunosuke C/O Canon Kabushiki Kaisha Iijima
- 👤 Hirofumi C/O Canon Kabushiki Kaisha Suda
- 👤 Kunihiko C/O Canon Kabushiki Kaisha Yamada
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 22:00
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/60; H04N23/67; H04N23/673
Claims Analysis
Total Claims: 45
Claim 1
Independent Claim
140 words
A one-chip integrated circuit for focus control, comprising: (A) filter means for extracting a predetermined frequency component, which changes in accordance with a focusing state, from an image pickup signal; (B) gate means for allowing only a predetermined signal component, corresponding to a portion in a predetermined focus detection region in a photographing field, of the signal output from said filter means to pass therethrough; (C) arithmetic means for generating an evaluation signal of the focusing state by performing predetermined processing for the predetermined signal component extracted by said filter means; (D) gate control means for controlling positions or the number of focus detection regions in the photographing field by controlling said gate means; and (E) interface means for making said filter means, said gate means, said arithmetic means, and said gate control means accessible by an external control circuit.
Claim 2
Dependent Claim
20 words
A circuit according to claim 1, wherein the external control circuit comprises a microcomputer having a control interrupt control line.
Claim 3
Dependent Claim
191 words
An automatic focus control apparatus using a one-chip integrated circuit for focus control, comprising: (A) focusing means for performing focusing; (B) image pickup means; (C) an integrated circuit for focus detection for outputting an evaluation signal, which changes in accordance with a focusing state, on the basis of an image pickup signal output from said image pickup means, said integrated circuit comprising a) gate means for setting a predetermined focusing detection region in a photographing field, and allowing only an image pickup signal, corresponding to a portion in the focus detection region, to pass therethrough, b) filter means for extracting a predetermined frequency component, which changes in accordance with the focusing state, from the image pickup signal corresponding to the portion in the focus detection region, c) arithmetic means for generating the evaluation signal by performing predetermined processing for the predetermined frequency component extracted by said filter means, and (d) interface means for outputting the evaluation signal, and receiving an external control signal; and (D) control means, connected to said integrated circuit for focus detection via said interface means, for controlling said focusing means on the basis of the evaluation signal.
Claim 4
Dependent Claim
25 words
A circuit according to claim 1, or apparatus according to claim 3, wherein said filter means comprises a digital filter having a variable frequency characteristic.
Claim 5
Dependent Claim
25 words
A circuit or apparatus according to claim 4, wherein said filter means comprises a plurality of digital filters having different frequency characteristics, which are variable.
Claim 6
Dependent Claim
18 words
A circuit or apparatus according to claim 5, wherein said filter means comprises a plurality of high-pass filters.
Claim 7
Dependent Claim
44 words
A circuit or apparatus according to claim 5, wherein said plurality of filters are switched in correspondence with even line scanning and odd line scanning of the photographing field, and output signals having different frequency bands at a period of a horizontal synchronization signal.
Claim 8
Dependent Claim
42 words
A circuit or apparatus according to claim 4, wherein said gate means can set a plurality of focus detection regions on the photographing field, and can extract the output from said filter means in each of the plurality of focus detection regions.
Claim 9
Dependent Claim
60 words
A circuit or apparatus according to claim 8, wherein said arithmetic means comprises a peak hold circuit for holding a peak value of the output from said filter means in each of the plurality of focus detection regions, and an integration circuit for integrating an output from said peak hold circuit in each of the plurality of focus detection regions.
Claim 10
Dependent Claim
44 words
A circuit or apparatus according to claim 9, wherein said peak hold circuit and said integration circuit can independently obtain a peak value and an integration value in each of even and odd scanning lines in each of the plurality of focus detection regions.
Claim 11
Dependent Claim
23 words
A circuit or apparatus according to claim 10, wherein said filter means has different frequency characteristics in the even and odd scanning lines.
Claim 12
Dependent Claim
54 words
A circuit or apparatus according to claim 10, wherein said arithmetic circuit further comprises a luminance peak detection circuit for detecting a peak value of a luminance in each of the plurality of focus detection regions, and a luminance difference detection circuit for detecting a difference between maximum and minimum values of the luminance.
Claim 13
Dependent Claim
40 words
A circuit or apparatus according to claim 12, wherein outputs from said peak hold circuit, said integration circuit, said luminance peak detection circuit, and said luminance difference detection circuit data-communicate with an externally connected control circuit via said interface means.
Claim 14
Dependent Claim
20 words
An apparatus according to claim 3, wherein said focusing means comprises a focusing lens and a focusing lens driving motor.
Claim 15
Dependent Claim
137 words
A one-chip integrated circuit for focus control, comprising: (A) Y/C separation means for receiving an image pickup signal, and separating a luminance signal and a color signal from the image pickup signal; (B) gate means for setting a predetermined focus detection region in a photographing field, and allowing only a luminance signal, corresponding to a portion in the focus detection region, to pass therethrough; (C) a plurality of digital filter means for extracting predetermined frequency components, which change in accordance with a focusing state, from the luminance signal corresponding to the portion in the focus detection region; (D) arithmetic means for generating an evaluation signal by performing predetermined processing for the predetermined signal components extracted by said plurality of digital filter means; and (E) interface means for outputting the evaluation signal, and receiving an external control signal.
Claim 16
Dependent Claim
23 words
A circuit according to claim 15, wherein said plurality of digital filter means comprise a plurality of high-pass filters having different frequency characteristics.
Claim 17
Dependent Claim
42 words
A circuit according to claim 15, wherein said plurality of filters are switched in correspondence with even line scanning and odd line scanning of the photographing field, and output signals having different frequency bands at a period of a horizontal synchronization signal.
Claim 18
Dependent Claim
49 words
A circuit according to claim 17, wherein said gate means can set a plurality of focus detection regions on the photographing field, and gate control means can extract the outputs from said digital filter means in each of the plurality of focus detection regions by controlling said gate means.
Claim 19
Dependent Claim
99 words
A circuit according to claim 18, wherein said arithmetic means comprises a peak hold circuit for holding a peak value of the output from said digital filter means in each of the plurality of focus detection regions, an integration circuit for integrating an output from said peak hold circuit in each of the plurality of focus detection regions, and a luminance peak detection circuit for detecting a peak value of a luminance in each of the plurality of focus detection regions, and a luminance difference detection circuit for detecting a difference between maximum and minimum values of the luminance.
Claim 20
Dependent Claim
42 words
A circuit according to claim 19, wherein said peak hold circuit and said integration circuit can independently obtain a peak value and an integration value in each of even and odd scanning lines in each of the plurality of focus detection regions.
Claim 21
Dependent Claim
38 words
A circuit according to claim 19, wherein outputs from said peak hold circuit, said integration circuit, said luminance peak detection circuit, and said luminance difference detection circuit data-communicate with an externally connected control circuit via said interface means.
Claim 22
Dependent Claim
13 words
A video camera mounting said integrated circuit for focus control of claim 15.
Claim 23
Dependent Claim
118 words
An automatic focus control apparatus comprising: (A) extraction means for extracting a predetermined frequency component, which changes in accordance with a focusing state, from an image pickup signal corresponding to a portion in a predetermined detection region set on a photographing field; (B) peak detection means for detecting a peak value of the frequency component corresponding to the portion in the detection region in units of horizontal scanning lines; (C) integration means for integrating an output from said peak detection means in the detection region; and (D) control means for controlling the focusing state on the basis of a peak value output from said peak detection means in the detection region, and an output from said integration means.
Claim 24
Dependent Claim
59 words
An apparatus according to claim 23, wherein said control means hill-climbing-controls a focusing lens on the basis of the output from said integration means, performs detection of an in-focus point on the basis of the outputs from said peak detection means and said integration means, and performs redriving on the basis of the output from said peak detection means.
Claim 25
Dependent Claim
34 words
An apparatus according to claim 23, wherein said extraction means comprises a plurality of high-pass filters having different frequency characteristics, which filters are alternately switched in correspondence with even and odd horizontal scanning lines.
Claim 26
Dependent Claim
35 words
An apparatus according to claim 23, wherein a plurality of said focus detection regions are provided, and the outputs from said peak detection means and said integration means can be obtained in units of regions.
Claim 27
Dependent Claim
42 words
An apparatus according to claim 26, further comprising: luminance peak detection means for detecting a peak value of a luminance in the image pickup signal; and luminance difference detection means for detecting a difference between maximum and minimum values of the luminance.
Claim 28
Dependent Claim
47 words
An apparatus according to claim 27, wherein said control means performs detection of high and low luminance values and controls said plurality of focus detection regions on the basis of an output from said luminance peak detection means and/or an output from said luminance difference detection means.
Claim 29
Dependent Claim
29 words
An apparatus according to claim 28, wherein said control means performs focus detection while ignoring the focus detection region from which the high and low luminance values are detected.
Claim 30
Dependent Claim
114 words
An automatic focusing apparatus comprising: filter means for extracting a predetermined frequency component used in focus detection from an image pickup signal output from image pickup means; gate means for extracting focus signals corresponding to a plurality of focus detection regions in a photographing field from a focus signal extracted by said filter means; extraction means for extracting luminance components of the plurality of focus detection regions in the photographing field; correction means for correcting the plurality of focus signals extracted by said gate means by outputs from said extraction means; and driving means for driving a focusing lens to an in-focus point on the basis of an output signal from said correction means.
Claim 31
Dependent Claim
22 words
An apparatus according to claim 30, wherein said extraction means holds peak values of the luminance components of the focus detection regions.
Claim 32
Dependent Claim
27 words
An apparatus according to claim 30, wherein said extraction means extracts a difference between maximum and minimum values of the luminance components of the focus detection regions.
Claim 33
Dependent Claim
123 words
An automatic focusing apparatus comprising: filter means for extracting a predetermined frequency component used in focus detection from an image pickup signal output from image pickup means; gate means for extracting only signals corresponding to a plurality of focus detection regions in a photographing field from a focus signal extracted by said filter means; a plurality of extraction means for extracting luminance components of the plurality of focus detection regions in the photographing field; and driving means for driving a focusing lens to an in-focus point on the basis of only the focus signals which pass through the focus detection regions corresponding to the luminance components equal to or smaller than a predetermined value of the outputs from said plurality of extraction means.
Claim 34
Dependent Claim
40 words
An apparatus according to claim 33, wherein said extraction means holds peak values of the luminance components of the focus detection regions, and extracts a difference between maximum and minimum values of the luminance components of the focus detection regions.
Claim 35
Dependent Claim
106 words
A focus detection apparatus comprising: (A) a plurality of band-pass filters for extracting predetermined frequency components from an image pickup signal; (B) switching means for switching said plurality of band-pass filters; (C) horizontal peak hold means for holding a peak value of an output from the band-pass filter selected by said switching means in synchronism with a horizontal synchronization signal; (D) vertical peak hold means for holding a peak value of an output from said peak hold means in a vertical direction; and (E) focus detection means for detecting a focusing state on the basis of the outputs from said horizontal and vertical peak hold means.
Claim 36
Dependent Claim
26 words
An apparatus according to claim 35, wherein said switching means switches said plurality of band-pass filters in correspondence with a frequency of the horizontal synchronization signal.
Claim 37
Dependent Claim
56 words
An apparatus according to claim 36, wherein a plurality of said vertical peak hold means are provided, and said apparatus further comprises second switching means for switching said plurality of vertical peak hold means to be interlocked with switching of said plurality of band-pass filters in synchronism with the horizontal synchronization signal of a video signal.
Claim 38
Dependent Claim
26 words
An apparatus according to claim 37 further comprising driving means for driving a focusing lens on the basis of an output from said focus detection means.
Claim 39
Dependent Claim
78 words
A video camera comprising: (A) focus detection means for performing focus detection on the basis of a focus signal extracted from a video signal; (B) determination means for determining a transition from an image recording standby state to an image recording state; and (C) control means for, when said determination means determines the transition in the image recording standby state and in a state wherein said focus detection means determines an in-focus state, redriving said focus detection means.
Claim 40
Dependent Claim
18 words
A camera according to claim 39, wherein the focus signal is a high-frequency component in the video signal.
Claim 41
Dependent Claim
88 words
An automatic focus detection apparatus comprising: (A) focus detection means for performing focus detection on the basis of a focus signal extracted from a video signal; (B) focusing means for performing focusing on the basis of the focus signal; and (C) control means for, when said focus detection means cannot detect a driving direction of said focusing means on the basis of the focus signal, determining the driving direction of said focusing means on the basis of a position of said focusing means and a predetermined standard position.
Claim 42
Dependent Claim
44 words
An apparatus according to claim 41, wherein said control means comprises direction determination means for slightly reciprocally oscillating said focusing means along an optical axis direction, and determining the driving direction of said focusing means on the basis of a change in focus signal.
Claim 43
Dependent Claim
42 words
An apparatus according to claim 42, wherein when the driving direction of said focusing means cannot be determined by the slight oscillation, said control means drives said focusing means to a standard position where an object is present with a high probability.
Claim 44
Dependent Claim
14 words
An apparatus according to claim 43, wherein said focusing means comprises a focusing lens.
Claim 45
Dependent Claim
35 words
Focus control device in which filter means extract a selected frequency component from part of an image signal, which part has been determined by gate means, and means utilising the frequency component for controlling focusing.
References Cited (Backward Citations)
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