JP2006220868A - Camera equipped with infrared ray detection mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose an appropriate disposition of an infrared detection mechanism when incorporating it in a camera. <P>SOLUTION: The camera includes an imaging section, a focus detecting section, an infrared ray detecting section, and a control section. The imaging section images a subject via a photographic optical system. The focus detecting section detects the focus of a subject. The infrared ray detecting section detects infrared ray from a focus detection luminous flux taken by the infrared ray detecting section, and judges the position of a person within an image plane according to the result of the infrared ray detection. The control section controls focusing and/or exposure, with priority given to the position of the person within the image plane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a camera that includes an infrared detection mechanism and determines a human subject in an object scene by infrared detection. In particular, the present invention relates to a device for arranging the infrared detection mechanism at an appropriate position in the camera in consideration of an optical path arrangement and a mounting space in the camera.

2. Description of the Related Art Conventionally, a camera that performs infrared detection and identifies a person in a subject has been proposed.
For example, Patent Document 1 describes a technique for detecting an infrared intensity distribution on a finder screen of a camera and specifying a surface temperature region near a human body temperature.
Patent Document 2 describes a technique in which a sensor lens is provided on the outside of a camera casing, and infrared rays are detected by a separate optical path from the photographing optical system.

JP-A-8-136971 (paragraph 0042, FIG. 2) Japanese Patent Laid-Open No. 7-36091 (FIG. 1)

  Patent Document 1 described above describes that an infrared intensity distribution is detected on the finder screen. However, there is no disclosure regarding where the infrared detection mechanism is arranged in the camera and how to detect infrared rays.

Patent Document 2 is a technique for detecting infrared rays in a separate optical path from the photographing optical system. For this reason, in short-distance shooting, a parallax occurs between an image captured by the shooting optical system and infrared rays detected by another optical path, and a position of person determination by infrared detection is shifted. In addition, in the infrared detection of another optical path, it is difficult to cope with a change in the shooting angle of view by the interchangeable lens or the zoom lens, and it is difficult to accurately identify the person position from that point.
Accordingly, an object of the present invention is to provide a technique for arranging an infrared detection mechanism at an appropriate position in a camera.

The camera of claim 1 includes the following imaging unit, focus detection unit, infrared detection unit, and control unit.
The imaging unit images the subject via the imaging optical system.
The focus detection unit performs focus detection.
The infrared detection unit detects infrared rays from the focus detection light flux captured by the focus detection unit, and determines the position of the person in the screen based on the detection results of the infrared rays.
The control unit performs focus control and / or exposure control with emphasis on the position of the person in the screen.

A camera according to a second aspect is the camera according to the first aspect, wherein the focus detection unit includes a focus detection unit and a sub mirror. The focus detection unit generates a set of divided images by dividing the imaging light flux of the photographing optical system into pupils, and detects the defocus amount based on the pattern deviation of the divided images. The sub mirror guides the imaging light beam to the focus detection unit on the optical path of the photographing optical system.
On the other hand, the infrared detection unit includes infrared separation means and a person determination unit. This infrared ray separating means separates infrared rays from the imaging light beam guided to the focus detection unit by the sub mirror. The person determination unit detects the separated infrared rays and determines the position of the person in the screen.

A camera according to a third aspect includes the following imaging unit, optical finder, infrared detection unit, and control unit.
The imaging unit images the subject via the imaging optical system.
The optical viewfinder is a means for observing a subject.
The infrared detection unit detects infrared rays from the light taken into the optical viewfinder, and determines the position of the person in the screen based on the detection results of the infrared rays.
The control unit performs focus control and / or exposure control with emphasis on the position of the person in the screen.

According to a fourth aspect of the present invention, in the camera according to the third aspect, the optical finder includes a photometric unit that takes light from the optical finder and performs photometry to obtain exposure control data.
On the other hand, the infrared detection unit includes infrared separation means and a person determination unit. The infrared ray separating means separates infrared rays from the light guided to the photometry unit. The person determination unit detects the separated infrared rays and determines the position of the person in the screen.

According to a fifth aspect of the present invention, in the camera according to the third aspect, the optical finder includes a focusing screen and an optical member that projects part or all of the imaging light beam of the photographing optical system and projects a subject image on the focusing screen. And an eyepiece optical system for observing a subject image generated on the focusing screen.
On the other hand, the infrared detector detects an object image generated on the focusing screen from an angle different from that of the eyepiece optical system, and determines the position of the person in the screen.

  According to a sixth aspect of the present invention, in the camera according to the fifth aspect, the optical finder includes a hologram element that deflects an infrared emission angle of the subject image. On the other hand, the infrared detector is arranged on the optical path of the infrared emission angle by the hologram element.

In general, in an ordinary photographing optical system, an infrared imaging position and a visible light imaging position are shifted in the optical axis direction (so-called axial chromatic aberration) due to a change in refractive index depending on a wavelength. Therefore, when infrared rays enter the focus detection unit, an error occurs in focus detection. Therefore, the conventional focus detection unit needs to cut infrared rays.
In view of this, the present inventor considered that the person determination is performed by effectively using the infrared rays cut by the focus detection unit.
In this case, even if the infrared rays are separated from the focus detection light beam, the visible light originally required by the focus detection unit is hardly affected, and the accuracy of focus detection can be suppressed to a level that does not cause a problem in practice.
In addition, since infrared rays are extracted from the focus detection light beam and detected, it is possible to accurately associate the determined position of the person in the screen with the focus detection area. Therefore, the configuration of claim 1 is particularly effective in the case where the result of person determination is reflected in the focus control.

According to another aspect of the camera of the present invention, the infrared rays are separated from the imaging light flux of the subject image guided to the focus detection unit by the sub mirror. Since the separated light flux has already passed through the photographing optical system, it forms an image as it is without separately installing an imaging lens. Therefore, in the configuration of claim 2, it is possible to omit the infrared imaging lens.
For the purpose of shortening the infrared imaging distance, an imaging lens may be newly arranged on the infrared optical path. In this case, since it is an infrared light beam which forms an image originally, the refractive power of the image forming lens additionally arranged can be weakened. Accordingly, the aberration of the imaging lens is suppressed to be small, and a relatively clear person determination is possible.

  According to another aspect of the camera of the present invention, infrared rays are detected from the light taken into the optical viewfinder, and the person is determined. In this configuration, since the infrared detection mechanism is disposed on the optical finder side, the infrared detection mechanism can be separated from the optical path of the imaging unit. Therefore, there is little possibility that the captured image of the imaging unit is blocked by the infrared detection mechanism, and vignetting of the captured image by the infrared detection mechanism can be prevented.

The camera according to claim 4 separates infrared rays from the light guided to the photometry unit and performs person determination.
In a normal photometry unit, infrared rays are cut so as not to measure invisible infrared rays.
Therefore, the present inventor has considered performing person determination by effectively using infrared rays cut by the photometry unit.
In this case, even if infrared rays are separated from the light beam for photometry, there is little influence on the visible light originally required by the photometry unit, and a decrease in photometry accuracy can be suppressed to a level causing no practical problem.
Further, since infrared rays are extracted from the light beam for photometry and detected, it is possible to accurately associate the determined position of the person in the screen with the photometry area. Therefore, the configuration of claim 4 is particularly effective in the case where the result of person determination is reflected in exposure control.

  According to a fifth aspect of the present invention, an object image generated on the focusing screen is infrared-imaged from an angle different from that of the eyepiece optical system to perform person determination. In this case, the eyepiece optical system and the infrared detection mechanism can be arranged independently. Therefore, in the camera according to the fifth aspect, the degree of freedom of arrangement of the infrared detection mechanism is increased, and the arrangement considering the mounting space in the camera is possible.

  The camera according to claim 6 deflects the infrared emission angle by the hologram element. An infrared detector is disposed on the optical path of this emission angle. Therefore, the infrared detection unit has higher infrared light receiving efficiency, and can detect weaker infrared rays accordingly.

<< First Embodiment >>
FIG. 1 is a diagram illustrating a camera 200 according to the first embodiment.
In FIG. 1, a photographic lens 100 is replaceably attached to a camera 200. A coupling portion 10 that performs signal connection and driving force transmission is provided at a connection portion between the camera 200 and the photographing lens 100.

The photographic lens 100 is provided with a lens group 1, an aperture 2, a drive mechanism 3, and a lens data unit 4 that stores information such as the correspondence between the defocus amount and the lens drive amount.
On the other hand, the quick return mirror 13 and the sub mirror 14 are positioned on the camera 200 along the photographing optical axis. Behind these mirrors, a shutter 11 and an image sensor 12 are arranged. In the case of a silver salt camera, a film is disposed in place of the image sensor 12.

  In the reflection direction of the quick return mirror 13, an optical viewfinder including a focusing screen 19, a pentaprism (or a reflective optical system such as a pentamirror) 6, and an eyepiece 15 is disposed. A split photometry unit 17 is also disposed in the vicinity of the pentaprism 6. The split photometry unit 17 takes in the light of the subject image formed on the focusing screen 19 from a different angle from the eyepiece lens 15 and performs split photometry.

The sub mirror 14 reflects the imaging light beam that has passed through the center of the quick return mirror 13. An infrared reflection filter 16 and a focus detection unit 5 are arranged in the reflection direction of the sub mirror 14.
The infrared reflection filter 16 transmits visible light necessary for focus detection and reflects infrared light unnecessary for focus detection. Since the infrared light beam reflected by the infrared reflection filter 16 is originally an imaging light beam of the photographing lens 100, an infrared image is formed as it is. An infrared imaging unit 18 is disposed at the imaging position of the infrared image. The infrared imaging unit 18 has sensitivity in the infrared wavelength range radiated from the body surface of a person.

On the other hand, the visible light transmitted through the infrared reflection filter 16 enters the focus detection unit 5. A conventional focus detection unit includes an infrared cut filter in order to remove unnecessary infrared rays. However, in the first embodiment, since infrared rays are removed by the infrared reflection filter 16, this infrared cut filter is omitted.
The focus detection unit 5 is a known pupil division phase difference detection block component. That is, the focus detection unit 5 generates a set of divided images by pupil-dividing the visible light imaging light flux, and detects the defocus amount based on the pattern deviation of the divided images.

  The camera 200 is provided with a microprocessor 9 for system control. The microprocessor 9 processes detection information of the infrared imaging unit 18, the split photometry unit 17, and the focus detection unit 5. Further, the microprocessor 9 refers to a lookup table (LUT) 7 based on the processing result of the detection information, and performs focus control and / or exposure control. This focus control is performed by the microprocessor 9 controlling the drive mechanism 3 and the in-body motor 8 (or in-lens motor) to move the focal lens group in the lens group 1 back and forth. Further, the exposure control is performed by the microprocessor 9 controlling the aperture value and exposure time at the time of shooting.

[Description of Operation of First Embodiment]
FIG. 2 is a flowchart for explaining a person determination operation by infrared detection.
The operation of the first embodiment will be described below along the step numbers shown in FIG.

Step S1: The microprocessor 9 determines from the contact signal of the release button (not shown) whether or not the release button is half pressed.
Here, if it is in the half-pressed state, the microprocessor 9 shifts the operation to step S2.
If not half-pressed, the microprocessor 9 returns to step S1.

Step S2: The microprocessor 9 calculates the pattern deviation of the divided image from the focus detection unit 5 for each focus detection area. The microprocessor 9 obtains defocus amounts for a plurality of areas in the screen based on the pattern shift.

Step S3: The microprocessor 9 detects a luminance distribution in the screen from each pixel value of the divided photometry unit 17.

Step S4: The microprocessor 9 detects the position in the screen and the area range of a person (including a heated subject having a close temperature like an animal) based on the result of imaging the infrared image obtained from the infrared imaging unit 18. .
The microprocessor 9 obtains information on the shooting distance and the focal length from the shooting lens 100 side, calculates the shooting magnification, and determines the size condition (vertical dimension, area, circle radius, etc.) of the person. The microprocessor 9 selects only the region of the infrared image that meets this size condition. By such processing, it becomes possible to increase the correct answer rate of person determination.

Step S5: The microprocessor 9 selects a focus detection area that matches the position of the person in the screen, and sets it as a focus detection area (hereinafter referred to as “selection area”) used for focus control. When the person's region range is wide and includes a plurality of focus detection areas, the microprocessor 9 selects these focus detection areas as a group, and selects the area where the defocus amount is closest to the selected area as the selection area. To do.

Step S6: When the camera 200 is set to the manual focus mode, only the focus aid operation for the selected area is performed, and focus control is not performed.
On the other hand, when the camera 200 is set to the autofocus mode, the microprocessor 9 inquires the lens data unit 4 about the defocus amount of the selected area and determines the lens drive amount. In accordance with this lens driving amount, the in-body motor 8 (or in-lens motor) is driven to control the focus of the taking lens 100. This focus control makes it possible to focus on the position of the human subject in the screen.
When the camera 200 is set to the AF-S (single AF) mode, the focus control is locked at the time when the person subject is focused.

Step S7: The microprocessor 9 weights and evaluates the luminance distribution of the divided photometry unit 17 with an emphasis on the position of the person in the screen, and obtains an evaluation photometric value. The microprocessor 9 inquires of this evaluation photometric value to the LUT 7 and determines exposure (aperture value, exposure time, imaging sensitivity, etc.).

Step S8: The microprocessor 9 determines from the contact signal of the release button (not shown) whether or not the release button is fully pressed.
Here, if it is in the fully-pressed state, the microprocessor 9 shifts the operation to step S9.
If not fully depressed, the microprocessor 9 returns to step S1.

Step S9: The microprocessor 9 flips up the quick return mirror 13 and the sub mirror 14, and retracts from the photographing optical path.

Step S10: When the camera 200 is set to the AF-C (continuous AF) mode, the microprocessor 9 calculates the expected defocus amount of the selected area from the past history of the defocus amount. The microprocessor 9 performs focus control according to the expected defocus amount.

Step S11: When the camera 200 is set to the manual exposure mode, the microprocessor 9 performs exposure control according to the manual setting value.
On the other hand, when the mode is set to other than the manual exposure mode, the microprocessor 9 performs exposure control according to the exposure (aperture value, exposure time, imaging sensitivity, etc.) determined in step S7. For example, the microprocessor 9 controls the exposure of the subject image based on the aperture value of the aperture 2, the opening / closing time interval of the shutter 11, the charge accumulation time of the image sensor 12 (electronic shutter), the signal gain (imaging sensitivity) of the image sensor 12, and the like. To do.

Step S12: The microprocessor 9 lowers the quick return mirror 13 and the sub mirror 14.

Step S13: An image signal is scanned and read from the image sensor 12. This image signal is subjected to image processing through an image processing unit, an image compression unit, etc. (not shown), and then recorded and stored in a memory card. (In the case of a silver salt camera, the film is wound up.)

[Effects of First Embodiment]
In general, due to the longitudinal chromatic aberration of the taking lens 100, the image forming position is largely shifted between visible light and infrared rays. For this reason, when infrared rays are incident on the focus detection unit 5, the detection accuracy of the defocus amount decreases. In the configuration of the first embodiment, infrared rays that are originally unnecessary for focus detection can be used effectively for person determination.

  In the configuration of the first embodiment, since the person determination is performed directly from the focus detection light beam, the correspondence between the person detection position and the focus detection area can be accurately taken. Therefore, the configuration of the first embodiment is excellent in that the focus detection area where the person is located can be specified with high accuracy even if the focus detection area increases to several tens of points.

  Furthermore, in the configuration of the first embodiment, the infrared imaging light flux that has passed through the photographing lens 100 is used for person determination. Since this imaging light beam forms an infrared image as it is, it is not necessary to newly provide an infrared imaging lens. Further, since a high-definition infrared image can be obtained by the high-performance photographing lens 100, it is possible to accurately detect a boundary line for person determination.

<< Second Embodiment >>
FIG. 3 is a diagram illustrating the configuration of the second embodiment.
A feature of the second embodiment is that an infrared reflection filter 16a is arranged in the incident optical path of the split photometry unit 17, and an infrared imaging unit 18a is arranged in the reflection direction of the infrared reflection filter 16a. In addition, when separating infrared rays from the front of the imaging lens of the split photometry unit 17, an infrared imaging lens is disposed in front of the infrared imaging unit 18a. In this case, it is preferable that the imaging lens and the infrared imaging unit 18a are arranged in a tilt or shift manner so that the entire area of the plane of the focusing screen 19 is in focus. Instead of the imaging lens, the infrared reflection filter 16 may be a reflective concave surface that is optically transmissive to the imaging lens.
With the configuration described above, in the second embodiment, it is possible to perform person determination by separating infrared rays from a photometric light beam.

  Furthermore, in the second embodiment, an infrared detection mechanism is disposed in the vicinity of the pentaprism 6. Therefore, the infrared detection mechanism does not block the imaging light flux that forms an image on the image sensor 12, and problems such as vignetting do not occur in the image captured by the image sensor 12.

  In the second embodiment, since the infrared rays are separated by the infrared reflection filter 16a, the infrared cut filter of the split photometry unit 17 can be omitted.

  Furthermore, in the configuration of the second embodiment, since the person determination is performed directly from the luminous flux for divided photometry, the correspondence between the detection position of the person and the luminance distribution that is the photometry result can be accurately taken. Therefore, even if the photometric pixels of the divided photometric unit 17 are made multi-pixel, the correspondence between the person determination area and the photometric pixels can be taken with high accuracy. As a result, the infrared detection mechanism of the second embodiment is suitable for the case where the weight distribution evaluation of the luminance distribution is performed finely with emphasis on the person region.

<< Third Embodiment >>
FIG. 4 is a diagram illustrating the configuration of the third embodiment.
A feature of the third embodiment is that the infrared image is formed at a position where the subject image of the focusing screen 19 can be observed from an angle different from that of the eyepiece lens 15 (corresponding to the eyepiece optical system described in the claims) and the split photometry unit 17. The image lens and the infrared imaging unit 18b are arranged. An infrared transmission filter that transmits infrared light is disposed on the light receiving surface side of the infrared imaging unit 18b.

In the camera 200, the imaging light flux of the photographing lens 100 is reflected by the quick return mirror 13 (corresponding to the optical member described in the claims), and the subject image is projected onto the focusing screen 19. In the third embodiment, infrared rays are detected from the subject image to perform person determination.
In particular, in the third embodiment, an infrared detection mechanism is disposed in the vicinity of the pentaprism 6. For this reason, the infrared detection mechanism does not block the imaging light flux that forms an image on the imaging element 12, and vignetting does not occur in the image captured by the imaging element 12.
In the third embodiment, it is preferable that the imaging lens and the infrared imaging unit 18a are arranged in a tilt or shift manner so that the entire area of the plane of the focusing screen 19 is in focus.

<< 4th Embodiment >>
FIG. 5 is a diagram illustrating the configuration of the fourth embodiment.
A feature of the fourth embodiment is that a diffractive optical element 27, which is a kind of hologram element, is added to the configuration of the third embodiment described above. For example, the diffractive optical element 27 is disposed in the vicinity of the focusing screen 19. Due to the diffraction phenomenon of the diffractive optical element 27, the outgoing angle of infrared rays emitted from the human body surface is deflected toward the infrared imaging unit 18. The diffractive optical element 27 has a function of bending light in a predetermined wavelength range by a diffraction grating made of liquid crystal, for example.

  As described above, the infrared light receiving efficiency of the infrared imaging unit 18 can be increased by the diffractive optical element 27. Therefore, it becomes possible to detect weaker infrared rays with high sensitivity, and to determine a farther person.

<< Additional items of embodiment >>
In the above-described embodiment, the electronic camera has been described. However, the present invention is not limited to this. For example, the present invention can be applied to a silver salt camera by replacing the image sensor 12 with a film supply mechanism.

In the above-described embodiment, it is preferable that the focus and exposure be adjusted to the person determination position when setting the person-centered shooting mode (portrait mode, person image quality setting mode, etc.). As a result, it is possible to prevent inconveniences that a person is in focus and exposure when shooting a landscape or the like.
In the first embodiment, the infrared imaging unit 18 may be fixed to the back surface of the quick return mirror 13. In such a configuration, the infrared imaging unit 18 can be retracted from the imaging optical path as the quick return mirror 13 is flipped up. In this case, the infrared imaging unit 18 does not cause a harmful effect such as vignetting in the photographing optical path.

  It is also possible to arrange an infrared reflection filter and an infrared imaging unit on the optical axis of the eyepiece 15 (such as the position “A” shown in FIG. 3). Further, the infrared transmission filter and the infrared imaging unit can be arranged at a position where the focusing screen 19 is viewed from below (positions “B” and “C” shown in FIG. 4). By arranging the infrared detection mechanism at such a position, it is possible to accurately take the correspondence between the determination position of the person and the viewfinder observation image of the photographer.

  As described above, the present invention is a technique that can be used for a camera or the like.

It is a figure which shows the camera 200 of 1st Embodiment. It is a flowchart explaining the person determination operation | movement by infrared detection. It is a figure which shows the structure of 2nd Embodiment. It is a figure which shows the structure of 3rd Embodiment. It is a figure which shows the structure of 4th Embodiment.

Explanation of symbols

5 Focus Detection Unit 9 Microprocessor 11 Shutter 12 Image Sensor 14 Submirror 15 Eyepieces 16 and 16a Infrared Reflective Filter 17 Split Photometric Units 18, 18a and 18b Infrared Imager 27 Diffraction Optical Element

Claims (6)

An imaging unit for imaging a subject via a photographing optical system;
A focus detection unit for performing focus detection;
An infrared detection unit that detects infrared rays from a light beam for focus detection captured by the focus detection unit, and determines a position of the person in the screen based on the detection result of the infrared rays; and
And a control unit that performs focus control and / or exposure control with emphasis on the position of the person in the screen. The camera of claim 1,
The focus detection unit
A focus detection unit that generates a set of divided images by pupil-dividing an imaging light beam of the imaging optical system, and detects a defocus amount based on a pattern shift of the divided images;
A sub-mirror for guiding the imaging light beam to the focus detection unit on the optical path of the photographing optical system,
The infrared detector is
Infrared separation means for separating infrared rays from the imaged light beam guided to the focus detection unit by the submirror;
A camera comprising: a person determination unit that detects the separated infrared rays and determines a position of the person in a screen. An imaging unit for imaging a subject via a photographing optical system;
An optical viewfinder for observing the subject;
Detecting an infrared ray from the light taken into the optical viewfinder, and determining an in-screen position of the person based on the detection result of the infrared ray; and
And a control unit that performs focus control and / or exposure control with emphasis on the position of the person in the screen. The camera according to claim 3.
The optical viewfinder
A light metering unit that takes light from the optical viewfinder and measures the light, and obtains data for controlling the exposure;
The infrared detector is
Infrared separation means for separating infrared light from the light guided to the photometry unit;
A camera comprising: a person determination unit that detects the separated infrared rays and determines a position of the person in the screen. The camera according to claim 3.
The optical viewfinder
A focusing screen,
An optical member that guides part or all of the imaging light flux of the photographing optical system and projects a subject image on the focusing screen;
An eyepiece optical system for observing the subject image generated on the focusing screen;
The infrared detector is
A camera, wherein the subject image generated on the focusing screen is imaged by infrared imaging from a different angle from the eyepiece optical system to determine the position of the person in the screen. The camera according to claim 5, wherein
The optical finder includes a hologram element that deflects an infrared emission angle of the subject image,
The infrared detection unit is disposed on an optical path of the infrared emission angle.

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