WO2002099496A1 - Capteur d'etat de mise au point - Google Patents

Capteur d'etat de mise au point Download PDF

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Publication number
WO2002099496A1
WO2002099496A1 PCT/JP2002/005437 JP0205437W WO02099496A1 WO 2002099496 A1 WO2002099496 A1 WO 2002099496A1 JP 0205437 W JP0205437 W JP 0205437W WO 02099496 A1 WO02099496 A1 WO 02099496A1
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WO
WIPO (PCT)
Prior art keywords
focus state
point
focus
state detection
detected
Prior art date
Application number
PCT/JP2002/005437
Other languages
English (en)
Japanese (ja)
Inventor
Tadashi Sasaki
Masao Wada
Tetsuji Inoue
Ryoji Kumaki
Shinobu Nakamura
Haruo Tominaga
Hiroyuki Horiguchi
Hideaki Sugiura
Masayuki Sugawara
Original Assignee
Fuji Photo Optical Co., Ltd.
Nippon Hoso Kyokai
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fuji Photo Optical Co., Ltd., Nippon Hoso Kyokai filed Critical Fuji Photo Optical Co., Ltd.
Publication of WO2002099496A1 publication Critical patent/WO2002099496A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
    • G02B7/28—Systems for automatic generation of focusing signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/60—Control of cameras or camera modules
    • H04N23/63—Control of cameras or camera modules by using electronic viewfinders
    • H04N23/633—Control of cameras or camera modules by using electronic viewfinders for displaying additional information relating to control or operation of the camera
    • H04N23/635—Region indicators; Field of view indicators
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/60—Control of cameras or camera modules
    • H04N23/67—Focus control based on electronic image sensor signals
    • H04N23/675—Focus control based on electronic image sensor signals comprising setting of focusing regions

Definitions

  • the present invention relates to a focus state detection device, and more particularly to a focus state detection device applied to focus state detection in autofocus and focus state display.
  • the autofocus of a video camera or the like is based on a contrast method.
  • a high-frequency component of a video signal within a certain range (focus area) of a video signal (luminance signal) obtained from an image sensor is integrated to obtain a focus evaluation value.
  • focus adjustment is automatically performed so that the focus evaluation value becomes maximum.
  • the best focus (focusing) that maximizes the sharpness (image contrast) of the image captured by the image sensor is obtained.
  • Japanese Patent Application Laid-Open Nos. Sho 55-763112 and Japanese Patent Publication No. Hei 7-62021 disclose a focus state of a photographing lens using a plurality of image sensors arranged at positions having different optical path lengths. It discloses a method to detect front focus, rear focus, and focus. For example, two focus state detection imaging elements that capture images in the same imaging range for an imaging element (video imaging element) that captures a video image have a longer optical path length than the video imaging element. And a shorter position. Then, based on the high-frequency components of the video signal obtained from these focus state detecting image pickup devices, the focus evaluation value for each imaging surface of each focus state detection image pickup device is obtained in the same manner as described above, and compared.
  • the focus state on the imaging surface of the image pickup device for the image that is, the front focus, the rear focus, or the in-focus state is detected from the magnitude relationship of the focus evaluation values.
  • Such a focus state detection method can be applied to, for example, focus detection for autofocus.
  • the center of the screen The subject is in focus.
  • the conditions for using the autofocus are limited, so in a broadcast camera that is required to be used under various conditions, it is desirable to focus within the range of the captured image ( AF point) must be specified.
  • a desired AF point to be focused on the viewfinder screen can be specified by a touch panel or the like.
  • Range (the range where focusing can be performed by autofocusing) may be limited to a certain range smaller than the imaging range of the imaging element for video. For example, when the imaging device for focus state detection is used as described above, the number of pixels of the imaging device for focus state detection is made smaller than that of the imaging device for video, and a part of the imaging range of the imaging device for video is focused. There may be a case where the imaging range of the detection imaging device is used.
  • the cameraman could not recognize the focus state detectable range and specified the AF point beyond that range, or specified the AF point beyond the focus state detectable range. In this case, the camera will not focus on the subject at the specified AF point, and the cameraman will not notice the fact that the subject is out of focus.
  • the present invention has been made in view of such circumstances, and it is possible to specify a target point for focus state detection, and the detectable range of the focus state is constant with respect to the imaging range of the image pickup device for video.
  • the focus is limited to the range, the photographer can reliably recognize the range in which the focus state can be detected, and can accurately recognize the point that is actually the focus state detection target. It is intended to provide a state detection device. Disclosure of the invention
  • a focus state detection device is provided with Photographed image display means for displaying a photographed image, a point designation means for designating an arbitrary point within a range of the photographed image displayed on a display screen of the photographed image display means, and a point designation means
  • Photographed image display means for displaying a photographed image
  • a point designation means for designating an arbitrary point within a range of the photographed image displayed on a display screen of the photographed image display means
  • a point designation means Focus state detection means for detecting a focus state of a subject at a point designated by the following, wherein the focus state detection range is limited to a certain range with respect to the entire range of the photographed image.
  • State detection means, and focus state detectable range display means for displaying a range in which the focus state can be detected by the focus state detection means on a display screen of the photographed image display means. I do.
  • the focus state detection device further includes: a point display unit that displays a position of the point designated by the point designation unit on a display screen of the photographed image display unit. If the specified point is not within the detectable range of the focus state, the focus state detecting means corrects the designated point to a predetermined point within the detectable range of the focus state. The focus state of the corrected point with respect to the subject is detected, and the point display means displays the corrected position of the point instead of displaying the position of the point specified by the point specifying means. I do.
  • the focus state detection device includes: a photographed image display unit that displays a photographed image photographed by a camera; Point designation means for designating an arbitrary point; point display means for displaying the position of the point designated by the point designation means on a display screen of the photographed image display means; designation by the point designation means Focus state detecting means for detecting the focus state of the focused object with respect to the subject, wherein the focus state is limited to a predetermined range in which the focus state can be detected for the entire range of the photographed image.
  • Focus state detection means detects the focus state for Bointo of the object to fix a predetermined Bointo is the modification of the detectable range of the focus state of the finger constant has been Bointo, the Boyne Bok display means Is characterized in that the corrected position of the point is displayed instead of displaying the position of the point specified by the point specifying means.
  • the point display means acquires a position of a point at which the focus state detection means has detected the focus state, and displays the acquired point position on a display screen of the photographed image display means.
  • the focus state detection means further includes a focus state detection imaging element different from the video imaging element for capturing the captured image, wherein the focus state detection unit includes one of the captured images captured by the video imaging element.
  • the range of the part is photographed by the focus state detecting image pickup device, and a focus specified by the point designation means based on the photographed image and a focus corrected by the focus state detection means with respect to one of the subjects. Detect state.
  • the focus state detection device includes a focus state display means for displaying a focus state detected by the focus state detection means, and a focus state detected by the focus state detection means. Focusing means for focusing on a subject at a point where the focus state detection means has detected the focus state.
  • the range in which the focus state can be detected is displayed on the display screen of the captured image, so that the cameraman can appropriately designate a target point for focus state detection within the range. Also, instead of the focus state detection target point specified by the cameraman being displayed on the captured image display screen as it is, the point at which the focus state detection was actually performed is displayed. It is possible to accurately recognize whether the subject at the point is a target of focus state detection.
  • FIG. 1 is a configuration diagram showing an overall configuration of a television camera system to which a focus state detection device according to the present invention is applied;
  • Figure 2 is a diagram showing a display example of a frame indicating a focus state detectable range and a mark indicating an AF point displayed on a screen of a Pew Finder;
  • FIG. 3 is a configuration diagram showing a configuration for performing focus state detection and autofocus processing in a photographing lens;
  • Figure 4 is a configuration diagram showing the configuration of the imaging unit for focus state detection
  • FIG. 5 is a diagram showing the image pickup devices A, B, and C for detecting a focus state on the same optical axis
  • FIG. 6 is a diagram showing the image pickup device of the camera body and the image pickup device for detecting the focus state being connected to the optical axis.
  • FIG. 2 is a diagram showing a comparison of the optical axis direction with overlapping;
  • FIG. 7 is a block diagram illustrating a configuration of a signal processing unit that performs focus state detection processing
  • FIG. 8 is a focus evaluation value of each focus state detection image sensor with respect to a focus position when a certain subject is photographed
  • FIG. 9 is an explanatory diagram used for describing a focus state detection process performed by the three focus state detection imaging elements.
  • FIG. 1 is a configuration diagram showing an overall configuration of a television camera system to which a focus state detection device according to the present invention is applied.
  • the television camera system shown in FIG. 1 includes a camera body 10, an interchangeable photographing lens 12, a viewfinder 14, an AF point indicating unit 16, an image processing unit 18, and the like.
  • the camera body 10 has a built-in image pickup device (image pickup device for video) that shoots images for broadcast.
  • the subject light formed through the image pickup lens 12 is converted into an electric signal by the image pickup device for video. Is converted.
  • the camera body 10 has a required signal processing circuit built therein, and the electric signal converted by the image pickup device for video is converted into a video signal of a predetermined format indicating a captured image by the signal processing circuit.
  • the video signal thus generated is output from the camera body 10 as a video signal for broadcast, or recorded on a recording medium as a video signal for recording, and photographed by a video imaging element.
  • the captured image in real time is output to a viewfinder 14 via an image processing unit 18 described later so that the photographer can visually recognize the captured image.
  • the photographing lens 12 is provided with a focus state detection unit 20 for detecting a focus state by a focus state detection image sensor different from the image pickup device.
  • the state detection unit 20 detects the focus state of the subject at the point (AF point) designated by the AF point designation unit 16 within the range of the captured image captured by the video image sensor.
  • the detected focus state is used for focus detection in auto focus, and based on the detected focus state, the focus of the photographing lens 12 is adjusted so that the subject at the designated AF point is focused.
  • the AF point indicating section 16 can be installed with a sunset panel on the screen of the viewfinder 14, and when the cameraman directly switches the point on the captured image displayed on the viewfinder 14 The position (coordinates) of the point is acquired as an AF point and output to the focus state detection unit 20.
  • the designated position of the AF point may be set and changed by position control using a predetermined AF point operation unit, or a joystick with a center return type
  • the setting of the designated position of the AF point may be changed by controlling the speed and the moving direction as described above.
  • the focus state detection unit 20 detects the focus state over the entire range (the entire imaging range) of a captured image captured by the image pickup device of the camera body 10.
  • the range over which focus can be detected (hereinafter referred to as the focus state detectable range), that is, the range of the subject that can be focused by autofocusing is limited to a part of the center.
  • the AF point designation by the AF point indicator 16 is not particularly limited to the focus state detectable range in consideration of the fact that the focus state detectable range may differ depending on the type of the shooting lens 12. This is possible within the entire imaging range of the image sensor for video (the entire range of the captured image displayed on the viewfinder 14). For this reason, if the AF point provided from the AF point indicating unit 16 is not within the focus state detectable range, the focus state detection unit 20 moves the AF point to a predetermined position within the focus state detectable range. After the correction, the focus state is detected for the AF point subject after the correction, and processing such as focusing on the subject is performed.
  • the focus state detection unit 20 provides the information of the focus state detectable range to the image processing unit 18 of the camera body 10 and the position of the AF point subjected to the focus state detection, that is, the AF point If the AF point given from the indicator 16 is within the focus state detectable range, it is the position of the AF point. If the AF point is corrected, the corrected AF point position is displayed as an image. This is given to the processing unit 18.
  • the image processing section 18 is provided from the focus state detection section 20 on a captured image (an image signal output from the camera body 10 for a viewfinder display image) captured by the video imaging device.
  • the frame indicating the focus state detectable range and the mark indicating the position of the AF point given from the focus state detection unit 20 are superimposed, and the image is output to the viewfinder 14.
  • a frame H indicating a focus state detectable range and an AF point are displayed on a screen 14 A of the view finder 14 (a captured image captured by a video image sensor).
  • An example of display showing the mark P indicating is shown.
  • the display of the focus state detectable range and the AF point need not be the method using the frame H or the mark P as shown in FIG. 2 as long as the display can be recognized by the cameraman.
  • the photographer can appropriately specify the AF point within the focus state detectable range.
  • the AF point that is actually the focus state detection target is displayed, allowing the cameraman to focus.
  • AF point when properly specified within the detectable range or AF point after correction when AF point is not specified within the focus state detectable range can be reliably known, and autofocus control This allows the user to know which subject is in focus without misunderstanding.
  • signals necessary for displaying the focus state detectable range, the AF point, and the like are provided. Since the signal does not pass through the inside of the camera main body 10, the same thing can be used without changing the camera specifications.
  • a mode in which the focus state detected by the focus state detection unit 20 is used for focus detection in autofocus will be described.
  • the present invention is not limited to this.
  • Just displaying the focus state detected by the focus state detection unit 20 on the viewfinder 14 in the same way as described above for the point specified on the screen 14 A of the viewfinder 14 is useful as reference information in manual focus. It is.
  • displaying the focus state detectable range and the point where the focus state was detected on the screen 14A of the viewfinder 14 in the same manner as described above can be appropriately performed within the focus state detectable range. Since the point can be specified, and when the specified point is not within the focus state detectable range, it is possible to reliably know which point the displayed focus state is for the subject. It is informative.
  • the focus state detection unit 20 limits the focus state detectable range to a certain range with respect to the imaging range of the video imaging device.
  • the focus state detection unit 20 described below is an example, and the present invention provides a focus state detection unit in which a focus state detectable range is limited to a certain range with respect to an imaging range of a video imaging device.
  • the present invention can be applied to all of those that perform state detection.
  • FIG. 3 is a configuration diagram showing a configuration for performing focus state detection and autofocus processing in the photographing lens 12.
  • the optical system of the photographing lens 12 includes a fixed focus lens F ', a movable focus lens F, a zoom lens Z including a variable power system and a correction system, A relay lens (relay optical system) composed of an iris I, a front relay lens R1 and a rear relay lens R2, and the like are arranged. Note that the configuration of each lens in the figure is simplified, and a lens group including a plurality of lenses is sometimes represented by one lens.
  • the optical path of the subject light between the front relay lens R1 and the rear relay lens R2 of the relay optical system is approximately 45 degrees with respect to the optical axis 0 of the photographing lens 12.
  • a half mirror or beam splitter that splits the subject light (light flux) into transmitted light and reflected light. 24 are placed.
  • the transmitted light that has passed through the beam splitter 24, that is, the subject light for video is emitted from the back end side of the taking lens 12, and the camera body 1
  • the light enters the imaging unit 22 at 0.
  • the configuration of the imaging unit 22 is omitted, the subject light that has entered the imaging unit 22 is separated into three colors of red light, green light, and blue light by, for example, a color separation optical system.
  • the light enters the imaging surface of the imaging device.
  • a blank video for broadcast is captured.
  • the focus plane 22 A in the figure shows an optically equivalent position on the optical axis O of the photographing lens 12 with respect to the imaging plane of each imaging element.
  • the beam splitter 24, the imaging unit 26, and the signal processing unit 28 shown in FIG. 1 constitute the focus state detection unit 20 in FIG.
  • the reflected light incident on the taking lens 12 and reflected by the beam splitter 24, that is, the subject light for focus state detection, travels along an optical axis O 'that is substantially perpendicular to the optical axis ⁇ of the taking lens 12.
  • the image is guided to the imaging unit 26 for focus state detection.
  • the subject light is in a substantially parallel light state
  • the subject light reflected by the beam splitter 24 is reflected by the rear relay lens R2.
  • the light passes through a light-collecting relay lens R3 having the same characteristics and enters the imaging unit 26 for detecting a pin state.
  • FIG. 4 is a configuration diagram showing the configuration of the imaging unit 26.
  • the imaging unit 26 is composed of three prisms P 1, P 2, and P 3 that constitute a light splitting optical system, and three imaging elements (two-dimensional CCD) A, B, Consists of C.
  • the object light reflected by the beam splitter 24 and traveling along the optical axis 0 ′ first enters the first prism P 1, and the entire surface of the beam splitter 4 of the first prism P 1 At 0, it is split into reflected light and transmitted light.
  • the light reflected by the entire surface 40 of the beam splitter enters the imaging surface of the imaging device C.
  • the light transmitted through the entire surface 40 of the beam splitter then enters the second prism P 2, and is further divided into reflected light and transmitted light by the entire surface 42 of the beam splitter of the second prism P 2.
  • the light reflected from the entire surface of the beam splitter 42 enters the image sensor B.
  • the light transmitted through the entire surface 42 of the beam splitter passes through the third prism P3 and enters the image sensor A.
  • the first and second prisms P1 and P2 have a beam splitter surface 40 and a beam splitter surface 42 so that the amounts of subject light incident on the image sensors A, B and C are equal.
  • the subject light is split.
  • the image pickup devices A, B, and C for detecting the focus state are CCDs for picking up a monochrome image in the present embodiment.
  • optical axis of the subject light that enters the image sensors A, B, and C is shown on the same straight line, as shown in Fig. 5, the optical axis until the light enters each of the image sensors A, B, and C
  • the image sensor B has the shortest optical path length and the image sensor C has the longest optical path length with respect to the subject light.
  • the optical path length of image sensor A is intermediate between the optical path lengths of image sensor B and image sensor C. Has become the length. That is, the imaging planes of the imaging element B and the imaging element C are arranged in parallel at the same distance before and after the imaging plane of the imaging element A.
  • the imaging surface of image sensor A has a conjugate relationship with the focusing surface 22 A of the camera body 10 (see FIG. 3), and the optical path length of the subject light incident on the imaging lens 12 is It coincides with the imaging surface of the imaging element for video of 0.
  • the light splitting optical system that splits the subject light into the image pickup devices A, B, and C is not limited to the configuration using the prisms P1 to P3 as described above.
  • FIG. 6 is a diagram showing the image pickup device of the camera body 10 and the image pickup devices A, B, and C for focus state detection with the optical axis superimposed and compared in the optical axis direction.
  • the image pickup device for video and the image pickup devices A, B, and C for focus state are different in the number of pixels and the image pickup size (light receiving size).
  • a 2 / 3-inch CCD with approximately 2.0 million pixels (1920 x 1082) is used as the image sensor for video, while image sensors A and A for focus state detection are used.
  • a 1/3 inch CCD of about 380000 pixels (768 x 494) is used for cost reduction.
  • the range in which the focus state can be detected by the processing described below using the imaging elements A, B, and C for detecting the focus state is smaller than the imaging range of the video imaging element, and the focus state detection range is as described above. Is limited to a certain range within the imaging range of the imaging element for video.
  • the subject light incident on the taking lens 12 is divided into three light paths having different optical path lengths arranged in the vicinity of the conjugate position with the focus surface 22 A of the power camera body 10. Images are picked up by the image pickup devices A, B, and C for focus state detection. Next, an outline of auto focus control based on focus state detection will be described. As shown in FIG. 3, images taken by three image pickup devices A, B, and C of an image pickup unit 26 for focus state detection are: The signal is taken into the signal processing unit 28. The signal processing unit 28 focuses the photographing lens 12 on the focusing surface 22 A of the camera body 10 based on the high frequency components of the images acquired from the image sensors A, B, and C, as described later.
  • the focus motor drive circuit 30 drives a focus motor (not shown), moves the focus lens F via a power transmission mechanism 32 composed of gears and the like, and instructs the focus lens F by the signal processing unit 28. Set to focus position. By performing such processing continuously, auto focus is controlled.
  • FIG. 7 is a block diagram showing a configuration of the signal processing unit 28.
  • the image of the subject captured by each of the imaging elements A, B, and C for focus state detection is output as a video signal of a predetermined format, and is output to each of the imaging elements A, B, and C.
  • high-pass filters 50, 60, 70, 80 converters 52, 62, 72, gate circuits 54, 64, 74, and adders 56, 6 The signal is converted into a focus evaluation value signal indicating the sharpness of the image (image contrast) by 6, 76 and input to the CPU 82.
  • the image sensor A in the present embodiment is a CCD that captures a black and white image, it is output from the image sensor A.
  • the video signal is output as a luminance signal indicating the luminance of each pixel constituting the screen.
  • the luminance signal output from the image sensor A is first input to a high-pass filter (HPF) 50, and a high-frequency component of the luminance signal is extracted.
  • HPF 50 is converted into a digital signal by the AZD converter 52.
  • the gate circuit 54 only digital signals corresponding to pixels in a predetermined area are extracted by the gate circuit 54 from digital signals for one screen (one field) of the image captured by the image sensor A, The values of the digital signals in the extracted range are added by the adder 56. This allows The sum of the values of the high frequency components of the luminance signal in the area extracted by the gate circuit 54 is obtained.
  • the area from which the signal is extracted by the gate circuit 54 (64, 74) is the AF point given from the AF point indicator 16 or the AF point indicator as shown in FIG. 16
  • the area surrounding the corrected AF point position when the AF point given from 6 is not within the focus state detection range is at least smaller than the entire imaging range of image sensor A (B, C). 6 (66, 76) is a focus evaluation value indicating the level of sharpness of an image in the area.
  • V signal vertical synchronization signal
  • FIG. 8 is a diagram showing the state of the focus evaluation value with respect to the focus position when a certain subject is photographed, with the horizontal axis representing the focus position of the photographing lens 12 and the vertical axis representing the focus evaluation value.
  • a curve a shown by a solid line in the figure shows a focus evaluation value obtained from the image pickup device A at a position conjugate with the focus plane 22 A of the camera body 10 with respect to the focus position, and a dotted line in the figure.
  • Curves b and c indicated by indicate the focus evaluation values obtained from the imaging elements B and C, respectively, with respect to the focus position.
  • the focus position F3 where the focus evaluation value of the curve a is maximum (maximum) is the focus position, but the focus position of the taking lens 12 is now set to the position of F1 in the figure.
  • the focus evaluation value obtained from each of the imaging devices A, B, and C is a value corresponding to the focus position F1 by the curves a, b, and c.
  • the focus position is set closer to the focus position F 3 which is the focus position.
  • the state has been performed, that is, the state of the front pin.
  • the focus position of the taking lens 12 is set to the position of F2 in the figure
  • the focus evaluation values obtained from each of the imaging elements A, B, and C are represented by curves a, b, and c. This is a value corresponding to the focus position F2.
  • the focus position is set to the infinity side from the focus position F3 which is the focus position. It can be seen that it is in the state of the back pin, that is, the state of the rear pin.
  • the focus evaluation values obtained from each of the image pickup devices A, B, and C are represented by curves a, b, and c. This is the value corresponding to position F3.
  • the focus position is set to the focus position F3, that is, in the focused state. You can see that there is.
  • the focus state of the imaging lens 12 at the current focus position is any one of the front focus, the rear focus, and the in-focus state. be able to.
  • the focus evaluation value obtained from the imaging elements B and C is sufficient, and the focus evaluation value obtained from the imaging element A is unnecessary. Therefore, it is possible to effectively use the focus evaluation values obtained from the three imaging elements A, B, and C, and directly detect the focus position at which the image is focused as follows.
  • the curves a, b, and c for the focus evaluation values obtained from the image sensors A, B, and C have substantially the same shape, and therefore, the focus obtained from the image sensors B and C at a certain focus position
  • the evaluation value can be regarded as a focus evaluation value of the image sensor A at a focus position displaced by a predetermined shift amount from the focus position.
  • the focus position is set to F4 in the figure on the curve a of the focus evaluation value of the image sensor A shown in FIG.
  • the focus evaluation value obtained from the image sensor A indicates the value of the point P A on the curve a.
  • the focus evaluation value obtained from the imaging element B represents a value of a point P B on the put that curve a to the focus position F 5 which is displaced by a predetermined shift Bok amount to the infinity side than the focus position F 4
  • the focus evaluation value obtained from image sensor C is The value of the point Pc on the curve a at the focus position F6 displaced by the predetermined shift amount closer to the side than the position F4 is shown. Note that the difference between the focus position F4 and the focus position F5, that is, the shift amount for the focus evaluation value obtained from the image sensor B is, for example, the focus position of the maximum point of the curve b in FIG.
  • the difference between the focus position of the curve a and the focus position of the maximum point, and the difference between the focus position F4 and the focus position F6, that is, the shift amount of the focus evaluation value obtained from the image sensor C is shown in FIG. In this case, it is equal to the difference between the focus position of the maximum point of the curve c and the focus position of the curve a and the maximum point.
  • curve a can be approximated by a predetermined function (for example, a quadratic curve). Therefore, the curve a can be specifically identified from the focus evaluation values at the three points P A , P B , and P c obtained from the respective image sensors A, B, and C, and the focus evaluation value is the largest in the curve a. Can be obtained.
  • a predetermined function for example, a quadratic curve
  • the CPU 82 in FIG. 7 detects a focus position at which focusing is performed based on the focus evaluation values obtained from the respective image sensors A, 'B, and C, the CPU 82 sets the focus position so that the focus position is reached.
  • a control signal is transmitted to the motor drive circuit 30 to move the focus lens F.
  • autofocus control is performed, and the subject at the AF point (or the corrected AF point) specified in the AF point indicating section 16 is focused.
  • the imaging surface is located at a position before and after the imaging surface is optically equidistant with respect to the imaging device A for focus state detection arranged at a position conjugate to the focusing surface 22 A of the camera body 10.
  • the image sensor B and the image sensor C are arranged, but the image sensors A, B are arranged so that the optical path lengths are different, and the optical path is set at a position conjugate to the focus plane 22 A of the camera body 10. It is sufficient that at least one of the image sensors A, B, and C is arranged at each of the position where the length becomes longer and the position where the length becomes shorter.
  • the shift amount may be set based on the distance between each of the image sensors B and C with respect to the image sensor A.
  • a method of calculating the shift amount for example, do not photograph a fixed subject. Then, the focus position is changed, and the focus position at which the focus evaluation value obtained from each of the image sensors A, B, and C is maximized is detected.
  • the amount of displacement of each focus position at which the focus evaluation value obtained from each of the imaging devices B and C is maximum is detected with respect to the focus position at which the focus evaluation value obtained from the imaging device A is the maximum.
  • the amount of displacement is defined as the shift amount.
  • the imaging surface of the imaging device A for detecting the focus state is arranged at a position conjugate with the focusing surface 22 of the camera body 10, but this is not always necessary. That is, the above-described method for detecting the amount of displacement of each focus position at which the focus evaluation value obtained from each of the imaging devices B and C is maximum with respect to the focus position at which the focus evaluation value obtained from the imaging device A is maximum.
  • the amount of displacement of the focus position at which the focus evaluation value obtained from the image sensor A is the maximum is detected with respect to the focus position at which the focus is obtained on the focus surface 22A of the camera body 10, and the displacement is determined.
  • the amount be the amount of shift for the focus evaluation obtained from image sensor A. That is, the focus evaluation value obtained from the image sensor A is regarded as the focus evaluation value at the focus position displaced from the actual focus position by the shift amount. Note that the shift amount of the focus evaluation value obtained from the imaging devices B and C is detected in the same manner.
  • a curve of the focus evaluation value with respect to the focus plane 22 of the camera body 10 can be obtained based on the focus evaluation values of the respective image sensors A, B, and C obtained at a certain focus position, and the curve can be obtained. It is possible to find the focus position at which focus is achieved.
  • the three imaging elements A, B, and C for detecting the focus state are arranged in the imaging unit 26.
  • only the two imaging elements B and C for detecting the focus state are used in the camera body.
  • the auto focus Focus control may be performed.
  • the position where the optical path length becomes longer and the position where the optical path length becomes shorter with respect to the position conjugate to the focusing surface 22 A of the camera body 10 respectively.
  • the in-focus position may be detected more accurately by arranging at least one image sensor in the camera.
  • only one image sensor for focus state detection is shared with the focus surface 22 A of the camera body 10.
  • a so-called hill-climbing method that has been conventionally arranged may be adopted. That is, the focus position is moved in a direction in which the focus evaluation value obtained by the one image sensor increases, and the focus position is set so that the focus evaluation value becomes maximum. At this time, a method called coupling is used to detect the direction in which the focus evaluation value increases.
  • the focus lens F may be moved, or the imaging device for detecting the focus state may be moved by a predetermined drive mechanism. May be moved in the optical axis direction.
  • the focus state detection by the focus state detection device according to the present invention is applied to the autofocus.
  • the present invention is not limited to this, and may be used for other purposes such as displaying the focus state. You can also.
  • a mark or the like indicating the focus state front focus, rear focus, focus
  • a display other than the viewfinder 14 may be displayed. It may be displayed on a container.
  • the range in which the focus state can be detected is displayed on the display screen of the captured image. Can be specified appropriately. Also, since the focus point for focus state detection specified by the cameraman is not displayed on the captured image display screen as it is, the point at which the focus state detection was actually performed is displayed. It is possible to accurately recognize which point of the subject is the subject of focus state detection.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Focusing (AREA)
  • Automatic Focus Adjustment (AREA)
  • Indication In Cameras, And Counting Of Exposures (AREA)
  • Studio Devices (AREA)

Abstract

L'invention concerne un capteur d'état de mise au point pour un système de caméra dans lequel lorsque l'opérateur spécifie le point AF en touchant l'écran du viseur d'une caméra de télévision, la caméra est mise au point sur l'objet au niveau du point AF par mise au point automatique. Si la plage de spécification du point AF est limitée, celle-ci s'affiche sur le viseur pour que l'opérateur puisse correctement spécifier le point AF. Par ailleurs, un écran tactile surmonte le viseur (14) de la caméra de télévision. Lorsque l'opérateur touche le point (point AF) sur lequel la caméra est mise au point, la caméra doit être mise au point sur le point AF. Si la plage de spécification du point AF est limitée, une trame (H) indiquant la plage est affichée sur l'écran (14A) du viseur (14), le point AF (P) étant également affiché.
PCT/JP2002/005437 2001-06-04 2002-06-03 Capteur d'etat de mise au point WO2002099496A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2001168248A JP2002365519A (ja) 2001-06-04 2001-06-04 ピント状態検出装置
JP2001-168248 2001-06-04

Publications (1)

Publication Number Publication Date
WO2002099496A1 true WO2002099496A1 (fr) 2002-12-12

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JP (1) JP2002365519A (fr)
WO (1) WO2002099496A1 (fr)

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US7561790B2 (en) 2004-12-28 2009-07-14 Fujinon Corporation Auto focus system
US7576796B2 (en) 2002-08-23 2009-08-18 Fujinon Corporation Auto focus system
US7590343B2 (en) 2005-03-15 2009-09-15 Fujinon Corporation Autofocus system
US7796879B2 (en) 2006-03-14 2010-09-14 Fujinon Corporation Autofocus system

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JP4147427B2 (ja) 2004-08-10 2008-09-10 フジノン株式会社 フォーカスコントロール装置
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JP4883413B2 (ja) * 2007-06-28 2012-02-22 ソニー株式会社 撮像装置、画像表示制御方法、プログラム
JP5064926B2 (ja) * 2007-08-02 2012-10-31 キヤノン株式会社 撮像装置及びその制御方法
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EP2466872B1 (fr) 2010-12-14 2018-06-06 Axis AB Procédé et caméra numérique pour améliorer la qualité des images dans un flux d'images vidéo
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