Camera control system

Abstract: A camera includes a photo-taking lens, an automatic focus adjusting device for effecting the automatic focus adjustment of the photo-taking lens, an eye-gaze detecting device (21) for detecting the photographer's eye-gaze position in a finder field corresponding to a photographing picture plane, and producing an eye-gaze detection signal corresponding to the eye-gaze position, a focus adjustment signal producing device for outputting a plurality of focus adjustment signals corresponding to a plurality of detection areas in the photographing picture plane, and a control signal producing device for producing a control signal for controlling the automatic focus adjusting means, on the basis of the eye-gaze detection signal and the focus adjustment signals. The control signal producing device produces the control signal on the basis of the plurality of focus adjustment signals corresponding to the plurality of detection areas when the eye-gaze position indicated by the eye-gaze detection signal is at a position between the plurality of detection areas.

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a camera provided with eye-gaze detecting means suitable for use, for example, in a camera such as a still camera or a video movie camera endowed with the function of detecting an eye-gaze position in the photographing picture plane (of various positions in the photographing plane, the position of the portion the user is gazing at) and controlling the auto focusing operation of a photo-taking lens or controlling the exposure of film or an image pickup element. Related Background Art As cameras of this kind, there are known cameras in which what portion in the photographing picture plane the photographer should recognize as the main object is determined on the basis of the result of the eye-gaze detection and a photo-taking lens is driven by the use of an information value representative of the focus detection state corresponding to the object in the determined portion to thereby effect so-called auto focusing. There are also known cameras in which automatic exposure control is effected by the use of an information value representative of the luminance of an object in the portion recognized as the main object on the basis of the eye-gaze detection (such cameras are disclosed, for example, in Japanese Laid-Open Patent Application No. 63-94232, Japanese Laid-Open Patent Application No. 1-241511 and Japanese Laid-Open Patent Application No. 2-5). However, in a camera wherein auto focusing is effected on the basis of the result of the eye-gaze detection, there may arise a problem as will be described below. Suppose a case where, as shown in Figure 7 of the accompanying drawings, a plurality of focus detection areas 1-3 are set in the photographing picture plane 10. Also assume that when the photographer gazes at between the focus detection area 1 and the focus detection area 2, the focus detection area nearer to the eye-gaze point is selected and a photo-taking lens is driven on the basis of an information value representative of the focus detection state in that area. Assuming that in the case of such a camera, the photographer's eye-gaze point is near the intermediate point a between the focus detection area 1 and the focus detection area 2 and as shown in Figure 8 of the accompanying drawings, the object distance D1 in the area 1 and the object distance D2 in the area 2 differ greatly from each other, the selected focus detection area will change over from the area 1 to the area 2 or from the area 2 to the area 1 simply if the eye-gaze point slightly moves unconsciously to right and left near the point a (the gaze of human being moves involuntarily even if it is gazing at one point). Each time the changeover takes place, the photo-taking lens is reciprocally driven between driven positions R1 and R2 as shown in Figure 9 of the accompanying drawings, and this results in the waste of electric power. This is a problem which will likewise arise when the vicinity of the intermediate point b between the focus detection areas 2 and 3 is gazed at. Also, if the eye-gaze point is moved from the left end to the right end of the picture plane or conversely, the selected focus detection area will change over when the eye-gaze passes the point a and the point b and therefore, in conformity therewith, the driving of the photo-taking lens will take place suddenly. Thus, in the case of a camera for photographing moving images like a video movie camera, the object distance focused in a photographed moving image varies suddenly and therefore, that moving image becomes very unnatural one. On the other hand, in a camera wherein automatic exposure is effected on the basis of the result of the eye-gaze detection, there may arise, for example, a problem as will be described below. Assume that where as shown in Figure 10 of the accompanying drawings, a plurality of photometry areas 11-13 are set in the photographing picture plane 10, a photometry area corresponding to the photographer's eye-gaze point is selected and exposure is determined on the basis of the luminance information in that area. In the case of such a camera, assuming that the photographer's eye-gaze point is near the intermediate point a between the photometry area 11 and the photometry area 12 and as shown in Figure 11 of the accompanying drawings, the object luminance B1 in the area 11 and the object luminance B2 in the area 12 differ greatly from each other, the selected photometry area will change over from the area 11 to the area 12 or from the area 12 to the area 11 simply if the eye-gaze point slightly moves unconsciously to right and left near the point a. Accordingly, simply if in spite of having gazed at a single object present near the eye-gaze point a, the photographer slightly moves the eye-gaze point, the exposure amount as the result of automatic exposure control may greatly vary to E1 and E2 as shown in Figure 12 of the accompanying drawings. This is a problem which will likewise arise when the vicinity of the intermediate point b between the photometry areas 12 and 13 is gazed at. Also, if the eye-gaze point is moved from the left end to the right end of the picture plane or conversely, the selected photometry area will change over when the eye-gaze passes the point a and the point b and therefore, in conformity therewith, the exposure amount controlled will vary suddenly. Thus, in the case of a camera for photographing moving images like a video movie camera, the brightness of photographed moving images varies unnaturally suddenly. The documents US-A-5,327,191 (corresponding to DE-A-3841575) and US-A-5,291,234 (corresponding to DE-A-3803305) each disclose an eye direction detecting apparatus for use in an auto-focusing camera, in which focusing is performed on the basis of a focusing zone within the view field, selected on the basis of the detected eye direction. According to the present invention, there is provided a camera control system for controlling a photographic operation in response to the position in a photographic field at which a user is detected to be looking and selectively in response to measurements of parts of the object field corresponding to respective measurement areas in the photographic field, characterised in that the system is operable to calculate an interpolated measurement value based on the measurements from a plurality of said areas and to control the photographic operation on the basis of said interpolated measurement value when the detected position at which the user is looking is intermediate those areas. An advantage of the present invention is that it may provide a camera control system in which more adequate automatic focus adjustment and automatic exposure control can be effected on the basis of eye-gaze detection with a result that better images can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS Specific embodiments of the present invention will now be described with reference to the accompanying drawings, in which:- Figure 1 is a schematic view showing the internal structure of a camera provided with eye-gaze detecting means according to an embodiment of the present invention. Figure 2 is a graph showing a relation between the eye-gaze point by the camera of the Figure 1 embodiment and weighting coefficients. Figure 3 is a graph showing the relation between the eye-gaze point and the lens driven position. Figure 4 is a schematic view showing the internal structure of a camera provided with eye-gaze detecting means according to another embodiment of the present invention. Figure 5 is a graph showing the relation between the eye-gaze point by the camera of the Figure 4 embodiment and weighting coefficients. Figure 6 is a graph showing the relation between the eye-gaze point and the exposure amount. Figure 7 shows the positions of focus detection areas and two particular eye-gaze points in the photographing picture plane. Figure 8 is a graph showing the relation between the two particular eye-gaze points shown in Figure 7 and focus detection state information (object distance information). Figure 9 is a graph showing the relation between the two particular eye-gaze points shown in Figure 7 and the lens driven position. Figure 10 shows the positions of photometry areas and two particular eye-gaze points in the photographing picture plane. Figure 11 is a graph showing the relation between the two particular eye-gaze points shown in Figure 10 and object luminance information. Figure 12 is a graph showing the relation between the two particular eye-gaze points shown in Figure 10 and the exposure amount. Figure 13 is a block diagram of an example of a camera. Figure 14 shows the divided patterns of the photometry areas and eye-gaze detection areas in the photographing picture plane of the Figure 13 example. Figure 15 shows an example in which the divided patterns of the eye-gaze detection areas of Figure 14 have been changed. DESCRIPTION OF THE PREFERRED EMBODIMENTS Figure 1 shows the internal structure of a camera according to an embodiment of the present invention. This camera effects automatic focus adjustment on the basis of the result of the eye-gaze detection. In Figure 1, the reference numeral 21 designates an eye-gaze detecting device for detecting the photographer's eye-gaze point in the photographing picture plane 10. The eye-gaze detecting device 21 is contained in a housing 22. The reference numeral 23 denotes a focus detecting apparatus for the camera. The focus detecting apparatus 23 is provided below the eye-gaze detecting device 21 and is contained in the housing 22. This focus detecting apparatus has contained therein a first calculating device (not shown) for calculating information values (information values relating to the object distances in a plurality of areas 1-3 in the photographing picture plane 10) D1-D3 representative of the focus detection states of a photo-taking lens 23 corresponding to the plurality of focus detection areas 1-3 (Figure 7) in the photographing picture plane 10. The reference numeral 25 designates a control device for controlling the amount of driving of the photo-taking lens 24 by a mean information value D calculated by itself. The control device 23 is connected to the focus detecting apparatus 23 and the eye-gaze detecting device 21. The mean information value D is calculated in the following manner by a second calculating device (not shown) contained in the control device 25. That is, the second calculating device determines the weighting coefficients k1-k3 of the focus detection areas 1-3 on the basis of the photographer's eye-gaze point by the characteristic lines k1-k3 of the coefficients shown in Figure 2, and calculates the mean information value D by an operation expression D = (k1 x D1 + k2 x D2 + k3 x D3) ÷ (k1 + k2 + k3) . The reference numeral 26 denotes a motor for moving the photo-taking lens 24 in the direction of the optical axis thereof, and the reference numeral 27 designates a sub-mirror for directing a light beam transmitted through a half-mirror 28 to the focus detecting apparatus 23. The reference numeral 29 denotes a pentaprism, and the reference numeral 30 designates a finder screen. Description will now be made of an example of the calculation for finding the mean information value D from the information values D1-D3. Assuming for example that the eye-gaze point is at a point c indicated in the abscissa of Figure 2, when the weighting coefficients k1-k3 of this eye-gaze point c are determined in accordance with the coefficient characteristic lines of Figure 2, they are 0.65, 0.35 and 0, respectively, as indicated in the ordinate of Figure 2. Assuming that the information values D1-D3 representative of the focus detection states in the focus detection areas 1-3 are values greatly differing from one another as shown in Figure 8, the mean information value D is as follows: D = (0.65 x D1 + 0.35 x D2 + 0 x D3) ÷ (0.65 + 0.35 + 0) = 0.65 x D1 + 0.35 x D2 When the amount of driving of the photo-taking lens 24 is controlled on the basis of the mean information value D obtained in this manner, the change in the lens position in the intermediate area of the focus detection areas becomes smooth as shown in Figure 3 even if the eye-gaze point changes delicately. While the present embodiment has been shown with respect to a case where there are three focus detection areas 1-3, the present invention is not restricted thereto. There may be two focus detection areas, or four or more focus detection areas. Where there are four or more detection areas, the lens driving will be effected more smoothly. In such case, the mean information value D can be calculated from an operation expression D = (k1 x D1 + k2 x D2 + ... + kn x Dn) ÷ (k1 + k2 + ... + kn) . However, information values representative of the focus adjusted states of the photo-taking lens corresponding to the focus detection areas 1-n in the photographing picture plane are D1, D2, ..., Dn, and the weighting coefficients of the focus detection areas 1-n are k1, k2, ..., kn. The above-mentioned information values D1-D3 indicative of the focus detection states need not always correspond strictly to the object distances. Even information values (information from which can be known a rough standard of the amount of driving of the photo-taking lens necessary for focus adjustment and the direction of driving thereof) indicative of the amount and direction (front focus or rear focus) of defocus of the object image by the photo-taking lens can be applied to the present embodiment. In such case, if the detection of the information values and the calculation of the mean information value are repetitively effected while the photo-taking lens is driven, proper focus adjustment will be possible. While in the above-described embodiment, the automatic focus adjustment of the photo-taking lens has been effected in accordance with the mean information value D, the present invention is not restricted thereto, but design may be made such that automatic zooming is effected in the following manner on the basis of the mean information value D. That is, a motor for zooming is controlled so that the greater becomes the distance corresponding to the mean information value D, the more the photo-taking lens may be zoomed up and that the smaller becomes said distance, the more the photo-taking lens may be zoomed down, whereby the size of the object in the photographing picture plane can be made constant irrespective of the object distance. Description will now be made of a camera according to another embodiment of the present invention. This camera effects automatic exposure control on the basis of the result of eye-gaze detection. Figure 4 is a schematic view showing the internal structure of the camera according to this embodiment. In Figure 4, the reference numeral 31 designates an eye-gaze detecting device for detecting the photographer's eye-gaze point in the photographing picture plane 10. The eye-gaze detecting device 31 is contained in a housing 32. The reference numeral 33 denotes a photometry device for the camera. The photometry device 33 is provided above the eye-gaze detecting device 31 and is contained in the housing 32. This photometry device 33 has contained therein a first calculating device (not shown) for calculating information values B1-B3 representative of object luminances in a plurality of photometry areas 11-13 (Figure 10) in the photographing picture plane 10. The reference numeral 34 designates a control device for controlling the shutter speed of a shutter 35 and the amount of aperture of a stop 36 on the basis of a mean information value B calculated by itself. The control device 34 is connected to the photometry device 33 and the eye-gaze detecting device 31. The mean information value B is calculated in the following manner by a second calculating device (not shown) contained in the control device 34. That is, the second calculating device determines the weighting coefficients k11-k13 of the photometry areas 11-13 on the basis of the photographer's eye-gaze point by coefficient characteristic lines k11-k13 shown in Figure 5, and calculates the mean information value B by an operation expression B = (k11 x B1 + k12 x B2 + k13 x B3) ÷ (k11 + k12 + k13) . The reference numeral 37 denotes a mirror, the reference numeral 38 designates a pentaprism, the reference numeral 39 denotes a finder screen, and the reference numeral 40 designates a photo-taking lens. Description will now be made of an example of the calculation for finding the mean information value B from the information values B1-B3. Assuming for example that the eye-gaze point is at a point c indicated in the abscissa of Figure 5, when the weighting coefficients k11-k13 for this eye-gaze point c are determined in accordance with the coefficient characteristic lines of Figure 5, the are 0.65, 0.35 and 0, respectively, as shown in the ordinate of Figure 5. Assuming that the information values B1-B3 representative of luminances in the photometry areas 11-13 differ greatly from one another as shown in Figure 11, the mean information value B is as shown below. B = (0.65 x B1 + 0.35 x B2 + 0 x B3) ÷ (0.65 + 0.35 + 0) = 0.65 x B1 + 0.35 x B2 When the shutter speed of the shutter 35 and the amount of aperture of the stop 36 are controlled on the basis of the mean information value B obtained in this manner, the variation in the exposure amount at the boundary between the photometry areas will become smooth as shown in Figure 6 even if the eye-gaze point changes delicately. It can be seen from Figures 5 and 6 that there are areas in which the mean information value B is derived from only one information value B1, B2 or B3. When the eye-gaze point is intermediate those areas, the mean information value B is an interpolated value derived from more than one information value B1, B2, B3. While the present embodiment has been described with respect to a case where there are three photometry areas, the present invention is not restricted thereto, but there may be two photometry areas or four or more photometry area. The construction of an example will now be described with reference to Figure 13 and 14. The exposure calculating device, as shown in Figure 13, is comprised chiefly of a control unit (CPU) 141 for controlling the system of the camera, and the CPU 141 has connected thereto the outputs from a release button 142, an eye-gaze detecting device 143 and a divisional photometry device 144. The output of the CPU 141 is connected to an indicator 145 and an exposure control device 146. Also, the eye-gaze detecting device 143 and the divisional photometry device 144, as shown in Figure 14, divide the interior of the finder into five zones 151-155, i.e., the central portion, the top left portion, the top right portion, the bottom left portion and the bottom right portion, during photographing and effect eye-gaze detection and photometry, respectively, at each of the zones 151-155. The release button 142 is provided on a camera body, not shown, and by the photographer depressing the release button 142, a signal for directing photographing direction or the like is output to the CPU 141. The eye-gaze detecting device 143 is a device for detecting in which of the zones 151-155 the photographer's eye-gaze in the finder is positioned. As the eye-gaze detecting device 143, use can be made, for example, of a device which applies infrared illuminating light to the photographer's eye and detects the position of the eye-gaze by the reflected image from the cornea or the crystal lens (for example, the device disclosed in Japanese Laid-Open Patent Application No. 1-274736). The divisional photometry device 144 is a device for measuring the object luminance in the finder at each of the zones 151-155 shown in Figure 14, and it outputs the obtained luminance information to the CPU 141, which thus calculates the exposure value. The indicator 145 is a device for indicating the eye-gaze point position detected by the eye-gaze detecting device 143 and the exposure value calculated by the CPU 141. The exposure control device 146 is a device for controlling a shutter 147 and a stop 148 during photographing in conformity with the exposure value calculated by the CPU 141. The invention is not restricted to the above-described embodiments, but various modifications are possible within the scope of the invention. In the above example, the shapes of the divided zones for effecting photometry and the divided zones for eye-gaze detection are the same, whereas they need not always be the same, but for example, the divided zones for eye-gaze detection may be made narrower than the divided zones for photometry so as to be included in the divided zones for photometry. Also, the divided zones for photometry may be farther subdivided than in Figure 14. Figure 15 shows an example in which the eye-gaze detection areas are made narrower than the photometry areas. In Figure 15, the eye-gaze detection areas comprise horizontally 12 divisions x vertically 8 divisions, totalling to 96 divisions. These eye-gaze detection areas are approximated to the divided shapes of the photometry areas 151-155 of Figure 14 and are grouped for use for said weighting as indicated by thick lines in Figure 15. If the eye-gaze detection areas are thus sub-divided into a matrix form, the control as described in connection with Figure 5 and 6 will also become possible by using the result of the detection of the eye-gaze detection areas correspondingly to the focus detection areas differing in divided shape from the photometry areas 151-155, for example, the focus detection areas 1-3 of Figure 7. If this is done, automatic exposure control and automatic focus adjustment can be accomplished on the basis of the output of a single eye-gaze detecting device and therefore, construction will become simple. Among the above-described embodiments, in the embodiment shown in Figure 15, as is apparent from this figure, the ratio between the horizontal dimension and vertical dimension of each eye-gaze detection area is smaller than the ratio between the horizontal dimension and vertical dimension of the photographing picture plane. This shows that the resolving power in the horizontal direction of eye-gaze detection is higher than the resolving power in the vertical direction. Since the eyes of human beings move more often in the horizontal direction than in the vertical direction, it is rational to make the resolving power in the horizontal direction of eye-gaze detection higher. The term "eye-gaze" has been used throughout the foregoing description, and is intended to refer simply to the camera user looking at the photographic picture plane in an ordinary way. No implication of a particularly fixed or intent look is intended by the use of this term. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention.

Claims: A camera control system for controlling a photographic operation in response to the position (a; b; c) in a photographic field at which a user is detected to be looking and selectively in response to measurements (D 1 , D 2 , D 3 ; B 1 , B 2 , B 3 ) of parts of the object field corresponding to respective measurement areas (1, 2, 3) in the photographic field, characterised in that the system is operable to calculate an interpolated measurement value based on the measurements from a plurality of said areas and to control the photographic operation on the basis of said interpolated measurement value when the detected position (a; b; c) at which the user is looking is intermediate those areas. A camera control system as claimed in claim 1, including calculating means (25; 34) arranged to produce said interpolated measurement value by weighting said measurements (D 1 , D 2 , D 3 ; B 1 , B 2 , B 3 ) according to the distances between the corresponding areas (1, 2, 3) and the position (a; b; c) at which the user is detected to be looking. A camera control system as claimed in claim 1 or 2, wherein said measurements (D 1 , D 2 , D 3 ) are focus adjustment measurements corresponding to the respective areas (1, 2, 3), said system including lens adjusting means (25, 26) for focus adjustment of a photographic lens (24) according to said interpolated measurement value. A camera control system as claimed in claim 1 or 2, wherein said measurements are distance measurements corresponding to the respective areas, said system including lens adjusting means (25, 26) for adjustment of a photographic lens (24) according to said interpolated measurement value. A camera control system as claimed in claim 4, wherein said lens adjusting means (25, 26) is arranged to adjust the focus of the photographic lens (24) according to said interpolated measurement value. A camera control system as claimed in claim 4 or claim 5, wherein said lens adjusting means (25, 26) is arranged to adjust the zoom of the photographic lens (24) according to said interpolated measurement value. A camera control system as claimed in claim 1 or 2, wherein said measurements (B 1 , B 2 , B 3 ) are photometric measurements corresponding to the respective areas, said system including exposure control means (34) for controlling an exposure according to said interpolated measurement value (B). A camera including a camera control system (23, 25; 33, 34) as claimed in any preceding claim and eye-gaze detecting means (21) for detecting said position in the photographic field in which the user is looking.

Inventors: KATANO YUJI, SATO SHIGEMASA, SAYA DAISUKE, TAKAGI TADAO, UCHIYAMA SHIGEYUKI, KATANO, YUJI, SATO, SHIGEMASA, SAYA, DAISUKE, TAKAGI, TADAO, UCHIYAMA, SHIGEYUKI
Applicants: NIPPON KOGAKU KK, NIKON CORPORATION
Application year: 1991
Main classification: A61B3
IPC codes: G02B7