JP2007225891A - Range finder and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a range finder which performs range-finding in an optional area on an imaging screen while a camera body is made compact. <P>SOLUTION: The range finder 10 is equipped with a condenser lens 1, a variable shape mirror 2, a photodetector 3 and a range finding part 7. The condenser lens 1 and the variable shape mirror 2 form a plurality of optical images of a range-finding object within the imaging screen. The photodetector 3 receives the plurality of optical images. The range finding part 7 measures a distance to the range-finding object based on space in a predetermined baseline direction of the plurality of optical images received by the photodetector 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a distance measuring device that realizes an automatic focus adjustment function such as a single-lens reflex camera.

Recent single-lens reflex cameras automatically detect the focal position between the imaging position of the imaging optical system and the imaging surface of the film surface or CCD (Charge Coupled Device) or CMOS (Complementary Metal-Oxide Semiconductor). A ranging device for adjusting the focus is installed.
As a method often used in the distance measuring apparatus, there is a passive distance measuring method based on triangulation.
The principle will be described with reference to FIG. An object image formed at a desired position P′0 by the imaging optical system is divided into two images separated by a predetermined baseline length d′ 0 by the condenser lens 101, the folding mirror 102, and the two detection optical systems 103a and 103b. An image is formed again on the light receiving element 104 as an image. For example, when the image of the subject is formed at a position P ′s that is shifted from the position P′0, the distance between the two images on the light receiving element 104 is d′ s. At this time, the focus shift D′ i is measured from the difference between the baseline length d′ s and the baseline length d′ 0.
Further, in recent years, a camera equipped with a plurality of focus detection modules so that a focus shift can be detected in a plurality of areas of the imaging screen in order to adjust the focus in an area desired by the photographer (for example, other than the central area of the imaging screen). Is also known (for example, see Patent Document 1).
JP-A-6-67088

In order to arrange a plurality of high-precision focus detection modules, a large space is required, and it is difficult to reduce the size of the camera body.
In addition, since the base line direction is determined by the arrangement of the detection optical system, it is difficult to detect the image shift amount by the two detection optical systems depending on the pattern of the subject, and there is a problem that the ranging accuracy is deteriorated.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a distance measuring device that performs distance measurement in an arbitrary area of an imaging screen while realizing miniaturization of a camera body. Another object of the present invention is to provide a distance measuring device that can perform distance measurement with high accuracy regardless of the pattern of the subject.

A distance measuring device as a first invention includes a plurality of detection optical systems, a light receiving means, and a distance measuring means. The plurality of detection optical systems form a range-finding object in the imaging screen as a plurality of optical images. The light receiving means receives a plurality of optical images by the detection optical system. The distance measuring means measures the distance to the distance measuring object based on the intervals in the predetermined baseline direction of the plurality of optical images received by the light receiving means. The plurality of detection optical systems include a variable shape element.
Here, the light receiving means is, for example, an imaging device that photoelectrically converts the brightness of received light into the amount of electric charge. The distance measuring unit obtains a plurality of image shift amounts from, for example, a distribution in a direction along a predetermined baseline length of light received by the light receiving unit. Further, the distance measuring means stores in advance the relationship between the amount of deviation and the distance, and measures the distance from the obtained amount of deviation to the object of distance measurement. Note that the distance measured by the distance measuring unit may be a value of the distance to the distance measuring object itself or a value that can be converted into a distance to the distance measuring object. The base line direction means, for example, a direction along a line (base line) virtually set on the light receiving means, and more specifically, for example, a plurality of optical images are formed by a plurality of detection optical systems. Means a parallel movement direction for superimposing the plurality of optical images.
In the present invention, the plurality of detection optical systems include a deformable element. For this reason, for example, the optical axis of the detection optical system can be directed in an arbitrary direction, and distance measurement can be performed at an arbitrary position in the imaging screen. Furthermore, for example, a predetermined baseline direction determined by the arrangement of the detection optical system can be made variable, and the detection optical system can be appropriately arranged for each pattern to be imaged to improve detection sensitivity.

A distance measuring device as a second invention controls a shape of a variable shape element so that a selected distance measuring object forms an image on a light receiving means, and a target selecting means for prompting selection of a distance measuring object in an imaging screen. And a shape control means.
The object selecting means is, for example, means for causing the photographer to specify a position in the imaging screen. For example, the shape control means stores in advance the relationship between the position in the imaging screen and the shape of the variable shape element, and changes the shape of the variable shape element according to the position in the imaging screen designated by the target selection means. Change.
In the present invention, it is possible to select a distance measurement target in the imaging screen and perform distance measurement according to the photographer's intention. More specifically, it is possible to select a subject whose focus is to be adjusted in the imaging screen and perform distance measurement.
In the distance measuring apparatus as the third invention, the shape control means controls the inclination of the variable shape element in accordance with the selection by the object selection means.
In the present invention, it is possible to change the distance measuring object imaged on the light receiving means by controlling the inclination of the deformable element. Accordingly, it is possible to adjust the focus in an arbitrary region without providing a plurality of focus detection modules, and it is possible to realize downsizing.

The distance measuring device as the fourth invention further includes a baseline direction control means for controlling the shape of the deformable element so as to change a predetermined baseline direction.
In the present invention, the predetermined baseline direction determined by the arrangement of the detection optical system can be made variable, and the detection optical system can be appropriately arranged for each pattern to be imaged to improve the detection sensitivity.
In the distance measuring apparatus as the fifth invention, the base line direction control means controls the arrangement of the variable shape elements included in the plurality of detection optical systems.
In the present invention, the predetermined baseline direction determined by the arrangement of the detection optical system can be made variable, and the detection optical system can be appropriately arranged for each pattern to be imaged to improve the detection sensitivity.
In the distance measuring apparatus as the sixth invention, each of the variable shape elements included in the plurality of detection optical systems is provided in a single variable shape portion.
According to the present invention, it is possible to reduce the number of parts constituting the distance measuring device, and to provide a compact distance measuring device that is ready for assembly.
In the distance measuring device as the seventh invention, the deformable element has a plurality of divided reflecting members.

In the present invention, the characteristics of the detection optical system can be changed by controlling the plurality of divided reflection members.
An imaging apparatus as an eighth invention includes an imaging optical system, the distance measuring apparatus according to any one of the first to seventh inventions, and an imaging optical system that controls the imaging optical system according to distance measurement by the distance measuring apparatus. Control means.
In the present invention, it is possible to provide an imaging device that exhibits the same effects as those of the first to seventh inventions.

  According to the distance measuring apparatus of the present invention, since the optical axis of the detection optical system can be directed in an arbitrary direction, the distance measuring apparatus that performs distance measurement in an arbitrary area of the imaging screen while realizing downsizing of the camera body. Can be provided. In addition, since the base line direction determined by the arrangement of the detection optical system can be made variable, it is possible to provide a distance measuring device that can perform distance measurement with high accuracy regardless of the pattern of the subject.

(Embodiment 1)
<Configuration and action>
FIG. 1 is a schematic configuration diagram of a distance measuring device 10 according to Embodiment 1 of the present invention.
The distance measuring device 10 includes a condenser lens 1, a deformable mirror 2 having a first mirror unit 6a and a second mirror unit 6b, a light receiving element 3, a detection region control unit 4, a detection region selection unit 5, and a measurement unit. And a distance portion 7.
The condenser lens 1 is a lens that guides a subject image (primary image) formed by an imaging optical system or the like to the deformable mirror 2 and the light receiving element 3.
As shown in FIG. 2, the deformable mirror 2 includes a plurality of mirror elements 2a finely divided in a matrix. FIG. 2A is a side view of the deformable mirror 2, and FIG. 2B is a front view of the deformable mirror 2. The angle and height of each mirror element 2a can be adjusted arbitrarily. As a result, by adjusting the angle and height of each mirror element 2a so that each of the plurality of regions of the deformable mirror 2 forms a substantially concave mirror, the deformable mirror 2 includes the first mirror portion 6a and the first mirror portion 6a. 2 mirror portions 6b are formed. The primary image guided by the condenser lens 1 is re-imaged as a pair of secondary images on the light receiving element 3 by the first mirror portion 6a and the second mirror portion 6b.

The condenser lens 1, the first mirror unit 6a, and the second mirror unit 6b constitute a plurality of detection optical systems.
The light receiving element 3 (see FIG. 1) is an imaging device or the like that photoelectrically converts the brightness of received light into the amount of charge.
The distance measuring unit 7 measures the deviation of the image formation position of the primary image from the deviation amount of the pair of secondary images received by the light receiving element 3. This will be described in detail later.
The detection area selection unit 5 causes the photographer to specify an arbitrary area in the imaging screen, and outputs an area signal indicating the specified area to the detection area control unit 4.
The detection region control unit 4 acquires the region signal output from the detection region selection unit 5, and stores the region signal and the setting (angle and height) of each mirror element 2a of the deformable mirror 2 stored in advance in a ROM or the like. Each mirror element 2a is controlled according to the acquired area signal.
The detection area selection unit 5 causes the photographer to select a plurality of preset areas (for example, a plurality of areas obtained by dividing the imaging screen in a matrix), and outputs an area signal indicating the selected area. Also good.
Due to the operation of the detection area control unit 4, the image formation position is shifted at any point (for example, P0, Pw) included in any area of the subject image formed by an imaging optical system (not shown). If not, the condenser lens 1 and the first mirror unit 6a and the second mirror unit 6b re-image on the light receiving element 3 as a pair of secondary images separated by a predetermined baseline length d0. In FIG. 1, the light beam and the state of the deformable mirror 2 when the region centered on P0 is selected by the detection region selector 5 are indicated by solid lines, and the region centered on Pw is selected. The light beam and the state of the deformable mirror 2 are indicated by broken lines.

With reference to FIG. 3, the operation of measuring the focus shift of the selected detection area will be described.
A subject image formed at a desired position P0 by an imaging optical system or the like is received as two images separated by a predetermined base line length d0 by the condenser lens 1, the first mirror unit 6a, and the second mirror unit 6b. Re-image on top. On the other hand, when the subject image is formed at a position Ps shifted from the desired position P0, the interval between the pair of secondary images on the light receiving element 3 is shifted from the predetermined base line length d0 to ds.
The light receiving element 3 photoelectrically converts light and darkness of the received secondary image into an amount of electric charge, and outputs an electrical signal corresponding to the amount of electric charge.
The distance measuring unit 7 derives a distribution of electric signals along a predetermined baseline direction, and obtains a distance between a pair of secondary images. Specifically, for example, when the base line direction is the horizontal direction of the light receiving element 3, an electrical signal corresponding to the amount of charge from the light receiving element 3 is added to the vertical direction of the light receiving element 3. The light receiving element 3 is exposed at a portion receiving a pair of secondary images, and a pair of peaks corresponding to the pair of secondary images appears in the distribution of the electrical signals. By obtaining the interval between the respective peaks, the interval between the pair of secondary images on the light receiving element 3 can be obtained.
The distance measuring unit 7 stores in advance a relationship between the distance between the pair of secondary images and the amount of deviation of the image formation position in a ROM or the like, and determines the image formation position from the obtained distance between the pair of secondary images. Is obtained (distance Di in FIG. 1).

<effect>
Since the distance measuring device 10 includes the deformable mirror 2, the optical axis of the detection optical system can be directed in an arbitrary direction. Therefore, distance measurement can be performed in an arbitrary area in the imaging screen.
In addition, the configuration of the detection optical system can be simplified, and the distance measuring device 10 can be configured in a small size.
(Embodiment 2)
<Configuration / Function>
FIG. 4 is a schematic configuration diagram of the distance measuring device 20 according to the second embodiment of the present invention.
The distance measuring device 20 is characterized in that it includes a baseline direction control unit 8 that controls the deformable mirror 2. In addition, the same code | symbol is attached | subjected and shown to the structure which implement | achieves the function similar to the ranging apparatus 10 shown in FIG. 1, and the description is abbreviate | omitted.
The baseline direction control unit 8 controls the deformable mirror 2 based on a control routine described later with reference to FIG. Specifically, the baseline direction control unit 8 is based on the relationship between the baseline direction stored in advance in a ROM or the like and the setting (angle and height) of each mirror element 2a of the deformable mirror 2. To control. More specifically, when a primary image formed at a desired imaging position is re-imaged as a pair of secondary images on the light receiving element 3, no matter what direction the base line direction is set, The baseline direction control unit 8 controls each mirror element 2a of the deformable mirror 2 so that the interval between the secondary images with respect to each baseline direction becomes a predetermined interval d0.

The control routine of the baseline direction control unit 8 will be described in more detail with reference to FIG.
FIG. 5 shows an object having a luminance distribution in one direction (the luminance distribution is indicated by an arrow), the arrangement of the first mirror unit 6a and the second mirror unit 6b of the deformable mirror 2, the secondary image on the light receiving element 3, and the light reception FIG. 3 schematically shows an intensity distribution (signal pattern) of an electric signal along a predetermined baseline direction obtained from the element 3.
FIG. 5A shows a state in which the luminance distribution of the subject and the baseline direction are substantially orthogonal. In this case, the distribution of the electric signal obtained from the light receiving element 3 in the baseline direction has a steep peak (the difference between the peaks and the peak value is the value Ia). Therefore, the peak can be detected with high accuracy, and further, the secondary image interval (interval da) can be detected with high accuracy. Further, a deviation amount of the image forming position is obtained by a difference between the interval da and the predetermined interval d0.
On the other hand, FIG. 5B shows a case where the luminance distribution of the subject and the baseline direction are not substantially orthogonal and the arrangement of the deformable mirror 2 is the same as that shown in FIG. 5A. In this case, the distribution of the electric signal obtained from the light receiving element 3 in the baseline direction does not have a steep peak (the difference between the peak and the peak value is the value Ib). For this reason, the peak cannot be detected with high accuracy, and it is difficult to detect the interval between the secondary images with high accuracy.

For this reason, the baseline direction control unit 8 determines whether or not the distribution of the electrical signal obtained from the light receiving element 3 in the predetermined baseline direction has a steep peak when determining the amount of deviation of the imaging position.
Specifically, when the difference between the peaks and the peak value is larger than a predetermined threshold (for example, as shown in FIG. 5A), the interval between the secondary images is detected from the peak interval, and the imaging position Find the amount of misalignment.
On the other hand, when the difference between the peaks and the peak value is smaller than a predetermined threshold (for example, as shown in FIG. 5B), the baseline direction control unit 8 executes the following control loop. That is, the baseline direction control unit 8 first changes the baseline direction sequentially, and controls the deformable mirror 2 according to the baseline direction. At the same time, the baseline direction control unit 8 outputs a signal indicating the baseline direction to the distance measuring unit 7. The distance measuring unit 7 sequentially obtains the distribution of the electric signal obtained from the light receiving element 3 along the input base line direction, the peak value of the distribution of the electric signal corresponding to the pair of secondary images, and between the peaks. The base line direction in which the difference (value Ic) is maximum is searched, and the peak interval (base line direction interval) when the value Ic is maximum is detected. As a result, the distance measuring unit 7 detects the base-line-direction interval (interval dc) of the secondary image, and obtains the shift amount of the imaging position based on the difference between the interval dc and the predetermined interval d0.
According to the above control loop, the base line direction is determined so that the luminance distribution of the subject image and the base line direction are substantially orthogonal to each other, and the deformable mirror 2 can be controlled.

<effect>
Since the distance measuring device 20 includes the deformable mirror 2, the base line direction determined by the arrangement of the detection optical system can be made variable. Therefore, distance measurement can be performed with high accuracy regardless of the luminance distribution of the subject.
In addition, the configuration of the detection optical system can be simplified, and the distance measuring device 20 can be configured in a small size.
The baseline direction control unit 8 included in the distance measuring device 20 may be included in the distance measuring device 10. In other words, the operation described in this embodiment can be realized in combination with the operation described in Embodiment 1, and distance measurement can be performed while changing the baseline direction in an arbitrary area in the imaging screen. is there.
(Embodiment 3)
FIG. 6 is a schematic configuration diagram of the camera 30 according to Embodiment 3 of the present invention.
The camera 30 has been described in the imaging optical system 18, the CCD 19, the movable mirror 21, the focusing screen 11, the pentaprism 12, the eyepiece lens 13, the auxiliary mirror 14, and the first or second embodiment. A distance measuring device 10 (20) and an imaging optical system control unit 16 are provided.

A light beam focused on the imaging surface of the CCD 19 by the imaging optical system 18 at the time of shooting is partially reflected by the semi-transparent movable mirror 21 at the time of finder observation, and is focused on the focusing screen 11, and the pentaprism 12 and eyepiece 13. To the photographer's eyes.
The light beam transmitted through the movable mirror 21 is reflected by the auxiliary mirror 14 and forms an aerial image 17 in front of the distance measuring device 10 (20). The distance measuring device 10 (20) operates as described in the first embodiment or the second embodiment. For example, the distance measuring device 10 (20) detects a focus shift amount in an area selected by the photographer. The defocus amount is output to the imaging optical system control unit 16, and the imaging optical system control unit 16 controls the imaging optical system 18 so that the light beam forms an image on the imaging surface of the CCD 19 without defocusing.
With the above configuration, it is possible to provide the camera 30 that can perform focus adjustment in an arbitrary area in the screen. In addition, it is possible to provide the camera 30 that can perform focus adjustment with high accuracy regardless of the luminance distribution of the subject.

  INDUSTRIAL APPLICABILITY The present invention is suitable as a digital still camera, a digital video camera, or the like in a field where high-precision focus adjustment in an arbitrary area in a screen or high-precision focus adjustment not related to a subject is desired.

Schematic configuration diagram of the distance measuring apparatus according to the first embodiment. Schematic diagram illustrating a configuration example of a deformable mirror according to the first embodiment Explanatory drawing explaining the ranging operation of the ranging apparatus which concerns on Embodiment 1. FIG. Schematic configuration diagram of a distance measuring apparatus according to the second embodiment Explanatory drawing explaining the ranging operation of the ranging apparatus which concerns on Embodiment 2. FIG. Schematic configuration diagram of an imaging apparatus according to Embodiment 3 Schematic configuration diagram of a distance measuring device according to the prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Condenser lens 2 Deformable mirror 3 Light receiving element 4 Detection area control part 5 Detection area selection part 6a 1st mirror part 6b 2nd mirror part 7 Distance measuring part 8 Base line direction control part 10 Distance measuring device 11 Focusing screen 12 Penta prism 13 Eyepiece 14 Auxiliary mirror 16 Imaging optical system controller 17 Aerial image 18 Imaging optical system 19 CCD
20 Distance measuring device 21 Movable mirror 30 Camera

Claims (8)

A plurality of detection optical systems that form an image of a distance measurement object in the imaging screen as a plurality of optical images;
A light receiving means for receiving the plurality of optical images by the detection optical system;
A distance measuring means for measuring a distance to the distance measuring object based on a predetermined baseline direction interval of the plurality of optical images received by the light receiving means;
With
The plurality of detection optical systems include a deformable element,
Distance measuring device. Object selection means for prompting selection of the distance measurement object in the imaging screen;
Shape control means for controlling the shape of the deformable element so that the selected distance measuring object forms an image on the light receiving means;
Further comprising
The distance measuring device according to claim 1. The shape control means controls the inclination of the deformable element in accordance with the selection by the object selection means;
The distance measuring device according to claim 2. Baseline direction control means for controlling the shape of the deformable element so as to change the predetermined baseline direction;
Further comprising
The distance measuring device according to claim 1. The baseline direction control means controls the arrangement of the variable shape elements included in the plurality of detection optical systems;
The distance measuring device according to claim 4. Each variable shape element included in the plurality of detection optical systems is provided in a single variable shape portion.
The distance measuring device according to any one of claims 1 to 5. The variable shape element has a plurality of divided reflection members.
The distance measuring device according to any one of claims 1 to 6. An imaging optical system;
The distance measuring device according to any one of claims 1 to 7,
Imaging optical system control means for controlling the imaging optical system in accordance with distance measurement by the distance measuring device;
Comprising
Imaging device.

Images