JP2003121730A - Multispot range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely measure the distance to a center subject among respective subjects positioned in different measurement visual fields and to greatly shorten the arithmetic time needed for the distance measurement. SOLUTION: The multispot range finder has a couple of photodetecting means which receive light beams from the respective subjects positioned in the different measurement visual fields and a phase difference arithmetic means which computes the phase difference between image signals outputted from the couple of photodetecting means and measures the distances to the subjects in the respective measurement visual fields according to the arithmetic result of the phase difference arithmetic means; and the photodetecting means has a plurality of photoelectric converting elements arrayed at specified pitch and is characterized in that the photoelectric converting element pitch (p) at the center part c1 of the photodetecting means is smaller than the photoelectric converting element pitches 2p at peripheral parts r1 and l1. Then the distance to the center subject among the respective subjects in the respective measurement visual fields is measured with the image signal outputted from the center part of the photodetecting means and the distances to circumferential subjects among the subjects in the measurement visual fields are measured with the image signals outputted from the peripheral parts of the photodetecting means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a multi-point distance measuring device for measuring the distance between objects located in different measurement visual fields.

[0002]

2. Description of the Related Art Conventionally, as a distance measuring device for a camera, a device using a passive type triangular distance measuring method using external light is known. This type of distance measuring device has an autofocus optical system, receives the captured subject image with a pair of light receiving sensors, and performs a correlation calculation on the pixel data obtained by each to obtain the distance measuring data. Is configured.

FIG. 7 is a diagram for explaining a general passive distance measuring device.

In FIG. 7, 701 is a first light receiving sensor, 702 is a second light receiving sensor, 703 is a first light receiving lens, 704 is a second light receiving lens, and 705 is a subject.

Now, of the signal image A relating to the luminance distribution of the object 705 detected by the first light receiving sensor 701,
The displacement amount of the first light receiving lens 703 from the optical axis T1 is x
The displacement amount of the signal image B regarding the luminance distribution of the subject 705 detected by the first and second light receiving sensors 702 from the optical axis T2 of the second light receiving lens 704 is x2.

These displacement amounts x1 and x2 represent the phase difference of the signal image from the object 705 detected by the first light receiving sensor 701 and the second light receiving sensor 702. The distance between T1 and T2 is B, the distance between the first and second light receiving lenses and the light receiving surfaces of the first and second light receiving sensors is f, and the distance from the first and second light receiving lenses to the subject 705 is Given that the distance is L and the distance from the optical axis T1 to the subject 705 is x, x1 = x / L × f (1) from the principle of triangulation. Further, including the sign of the direction in which the image of the output signal appears with reference to the optical axis T1, -x2 = {(B-x) / L} xf (2). From these equations (1) and (2), L = f * B / (x1-x2) ... (3) can be calculated.

Then, the distance L to the object 705 can be calculated by obtaining the above (x1-x2), that is, the phase difference between the signal image A and the signal image B.

As an example of the method of detecting the phase difference between the signal images, at least one of the signal image information is shifted by a unit of 1 bit (bit) within a range of a predetermined shift amount (hereinafter referred to as a correlation shift amount). Calculate how many bits by calculating the correlation amount
It is known to detect whether a pair of image information matches when they are shifted.

In general, the light receiving sensor is composed of charge storage type photoelectric elements arranged with a predetermined pixel pitch, and by making the pixel pitch smaller, it is possible to detect an object having a fine pattern. At the same time, the resolution of the phase difference detection of the signal image obtained by the light receiving sensor can be increased, and the distance to the subject can be accurately measured.

[0010]

However, when the pixel pitch of the light receiving sensor is reduced, the amount of correlation shift for obtaining the phase difference of the obtained image signals increases and the number of pixels in the light receiving sensor also increases. To do. Especially, in a multi-point distance measuring device, it is necessary to perform a correlation calculation for each distance measuring point.
It takes a considerable amount of time only with a lot of calculation time, which is a major factor in increasing the release time lag of the camera.

(Object of the Invention) A first object of the present invention is to perform accurate distance measurement for a central object among objects located in different measurement fields of view and to significantly reduce the calculation time required for distance measurement. The present invention is intended to provide a multi-point distance measuring device that can be used.

A second object of the present invention is to achieve the first object and to measure the object distance by synthesizing image signals respectively output from the central portion and the peripheral portion having different photoelectric conversion element pitches. Even in such a case, it is an object of the present invention to provide a multipoint distance measuring device capable of performing distance measurement by correcting discontinuity and distortion of an image signal due to a difference in photoelectric conversion element pitch.

[0013]

In order to achieve the first object, the invention described in claim 1 is a pair of light receiving means for receiving light from each subject located in a different measurement visual field, and a pair of light receiving means. A phase difference calculating means for calculating the phase difference between the image signals output from the pair of light receiving means, and the distance between the objects located in the respective measurement visual fields is measured from the calculation result by the phase difference calculating means. In the point distance measuring device, the light receiving means has a plurality of photoelectric conversion elements arranged at a predetermined pitch, and the photoelectric conversion element pitch in the central portion of the light receiving means is
The photoelectric conversion element pitch of the peripheral portion is made smaller, and the distance of the central object among the objects positioned in each of the measurement visual fields is measured by the image signal output from the central portion of the light receiving means, and the periphery of the light receiving means is measured. A multi-point distance measuring device for measuring the distances of peripheral objects among the objects positioned in the respective measurement visual fields by the image signal output from the part.

In order to achieve the above second object,
The inventions according to claims 2 to 4 include a pair of light receiving means for receiving light from respective subjects in different measurement fields of view, and a phase difference calculating means for calculating a phase difference between image signals output from the pair of light receiving means. And a multi-point distance measuring device for measuring the distance of an object in each of the measurement fields of view from the result of the phase difference calculation means, in the light receiving means, a plurality of photoelectric conversion elements are arranged at a predetermined pitch. , The photoelectric conversion element pitch of the central portion of the light receiving means is configured to be smaller than the photoelectric conversion element pitch of the peripheral portion, and by the image signal output from the central portion of the light receiving means, A first distance measurement processing function of measuring the distance of the central object and measuring the distance of the peripheral objects among the objects positioned in the respective measurement visual fields by the image signal output from the peripheral portion of the light receiving means; , The serial image signal obtained by synthesizing the image signals output from the peripheral portion of the image signal and said light receiving means to be output from the central portion of the light receiving means, first measuring the subject distance 2
The multi-point measurement for correcting the discontinuity and distortion of the image signal due to the difference in the photoelectric conversion element pitch between the central portion and the peripheral portion when the image signals are combined by the second distance measuring processing. This is a distance device.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail based on the illustrated embodiments.

FIG. 1 is a block diagram showing a main part of a multipoint distance measuring apparatus according to an embodiment of the present invention.

In FIG. 1, 101 is a first light receiving sensor, 102 is a second light receiving sensor, 103 is a first light receiving lens, 104 is a second light receiving lens, 105 is a subject in the left direction (hereinafter referred to as subject L denotes a subject, 106 denotes a subject in the central direction (hereinafter, referred to as subject C), and 107 denotes a subject in the right direction (hereinafter, referred to as subject R).

The first light receiving sensor 101 and the second light receiving sensor 102 are r1, c1, l1 and r2, c2, l2.
The brightness distribution of the subject L at a normal photographing distance is divided by the first and second light receiving lenses into the l1 part of the first light receiving sensor 101 and the second light receiving sensor 102. Light is received at the l2 portion. Further, the luminance distribution of the subject C at a normal shooting distance is received by the first and second light receiving lenses at the c1 portion of the first light receiving sensor 101 and the c2 portion of the second light receiving sensor 102. Further, the luminance distribution of the subject R at a normal shooting distance is received by the first and second light receiving lenses at the r1 portion of the first light receiving sensor 101 and the r2 portion of the second light receiving sensor.

Further, the first light receiving sensor 1 in FIG.
The number of pixels of 01 and the pixel pitch will be described with reference to FIG.

In FIG. 3A, the first light receiving sensor 1
The pixel pitch of r1 and l1 parts of 01 is 2p, and c
The pixel pitch of 1st part is p which is 1/2 the pixel pitch of r1 and 11th part.

It should be noted that the r1, c of the first light receiving sensor are arranged so that the light receiving ranges in the left direction, the center direction and the right direction are the same.
The lengths of the sensors in the 1 and 11 parts are the same. Therefore, the number of pixels in the c1 portion is twice the number of pixels in the r1 and r2 portions.

Further, in FIG. 3A, only the first light receiving sensor 101 of FIG. 1 is shown, but the second light receiving sensor 1
02 also has the same configuration as that shown in FIG.

Next, the operation of the distance measuring device having the above configuration will be described with reference to the flowchart of FIG.

First, in step # 201, the first light receiving sensor 101 and the second light receiving sensor 102 perform a signal accumulating operation for distance measurement. Specifically, after the first light receiving sensor 101 and the second light receiving sensor 102 start signal accumulation, each region (r1, c1, l1) of the first light receiving sensor and each region (r2, r2 of the second light receiving sensor 102). c2, 12)
A CPU (not shown) detects the peak of the received light signal every time, and when the peak signal exceeds a predetermined amount, the signal accumulating operation in the area is finished. When the accumulation operation in all areas of the light receiving sensor is completed, the process proceeds to step # 202.

At step # 202, the phase difference between the signal image obtained at the c1 portion and the signal image obtained at the c2 portion is detected, and the distance to the subject C is calculated. Here, it is assumed that the means for detecting the phase difference and the means for calculating the distance to the subject C from the phase difference detection result are in a CPU (not shown). In the following step # 203, the distance to the subject R is calculated by detecting the phase difference between the signal image obtained in the r1 portion and the signal image obtained in the r2 portion.

In the next step # 204, the distance to the subject L is calculated by detecting the phase difference between the signal image obtained in the l1 part and the signal image obtained in the l2 part. Then, in the next step # 205, the above steps # 202 to # 2.
Based on the result of the distance measurement in 04, the CPU (not shown) determines the main subject, determines the lens focus position, and ends the series of distance measurement operations.

According to the above embodiment, the pixel pitches of the c1 portion and the c2 portion of the second light receiving sensor 102 are r1, l1 as in the first light receiving sensor 101 of FIG. 3 (a).
By making the pixel pitch smaller than the pixel portion, r2, and l2 portion, it is possible to accurately measure the distance of the subject in the central direction in which the main subject frequently exists.

Further, the light receiving sensor 101 'shown in FIG.
, The total number of pixels of the light receiving sensor is reduced as compared to the case where the pixel pitch is made smaller in the entire area of the light receiving sensor.
The distance calculation time can be shortened.

By the way, when the distance to the subject is a distance other than the normal photographing distance, that is, the closest distance, the distance measurement cannot be performed by the distance measurement operation of the flowchart of FIG.

Now, the relationship between the object distance, the light receiving position and the light receiving sensor will be described with reference to FIG. The description of the same reference numerals as those in FIG. 1 is omitted.

In the figure, 406, 406 ', 40
Reference numeral 6 ″ denotes a subject, and with the distance Lp from the light receiving lenses 103 and 104 as a boundary, the far side from Lp is the distance range in the normal shooting mode, and the near side is the distance range in the macro shooting mode. The subject 406 exists within the distance range in the normal shooting mode, and the subjects 406 ′ and 406 ″ exist within the distance range in the macro shooting mode.

First, since the signal image from the subject 406 within the distance range in the normal photographing mode is received by the c1 and c2 portions, the distance can be measured by the operation of the flowchart of FIG.

On the other hand, the signal image from the subject 406 'within the distance range in the macro photography mode is near the boundary between the c1 portion and the r1 portion of the first light receiving sensor 101, and c2 in the second light receiving sensor 102. Light is received near the boundary between the 1 and 2 parts. In the case of a subject 406 ″ at a closer distance, the light is received by the r1 portion and the l2 portion.

Therefore, as in the operation of the flowchart of FIG. 2, only the signal image obtained by the c1 and c2 parts is calculated (#
In 202), the distance of the subject 406 ′ or 406 ″ cannot be measured.

Therefore, in the distance measuring apparatus of FIG. 4, the distance measuring operation in the macro photographing mode will be described below with reference to the flowchart of FIG.

First, in step # 501, the r1 and c1 portions of the first light receiving sensor 101 and the c2 and l2 portions of the second light receiving sensor 102 perform a signal accumulating operation for distance measurement. For details, see c1, r1 and c2, 12 (see FIG.
After the signal accumulation is started in C), the peaks of the received light signals of the r1 and c1 parts and the peaks of the received light signal of the c2 and l2 parts are indicated by C (not shown).
When it is detected by the PU and the peak signal exceeds a predetermined amount, the signal accumulating operation in that area is ended. R of each light receiving sensor
When the accumulating operation in the 1, c1 section and the c2, 12 section is completed,
Move to step # 502.

In step # 502, the above step # 5 is executed.
The light receiving signal obtained in 01 is discontinuous or distorted at the boundary where the pixel pitch changes, so the light receiving signal is corrected.

An example of the correction method will be described in detail below.

FIGS. 6A and 6B are received light images received on the c1 and r1 portions of the first light receiving sensor 101 and the c2 and l2 portions of the second light receiving sensor 102, respectively. FIG. 6 (c)
And (d) show the amount of signals accumulated by the light receiving sensors of the light receiving images of FIGS.

Here, when the sensor surface illuminance by the received light image and the signal storage time are the same, the signal amount of each pixel is proportional to the pixel area. In the present embodiment, the first light receiving sensor 1
Since the pixel area of the c1 portion of 01 is 1/2 that of the r1 portion, the signal amount of the c1 portion is 1/2 that of the r1 portion (the pixel pitch of the c1 portion is smaller than that of r1). Because it is 1/2).

Therefore, c1 is added to the signal amount of the r1 part.
The signal amount of the part becomes low, and the signal at the boundary between the c1 part and the r1 part becomes discontinuous. Therefore, from the pixel area ratio, c
By doubling the signal amount of one part, the discontinuity and the distortion when the signal image is formed from the signal of each pixel are corrected.

Further, the c2 portion and the l2 portion of the second light receiving sensor 102 are similarly corrected.

FIGS. 6 (e) and 6 (f) show the signal images after correction, and it can be seen that the discontinuity of the signal amount at the boundary where the pixel pitch is different is corrected.

Returning to FIG. 5, after the received light signal is corrected as described above, the process proceeds to step # 503, where c1 and c
Signal processing is performed in order to equalize the pixel pitches of the two parts and the r1 and l2 parts. Because next step # 504
Then, when detecting the phase difference between the signal image obtained at the r1 and c1 portions and the signal image obtained at c2 and l2, the correlation between different pixel pitches cannot be calculated.

Therefore, interpolation processing is performed on the pixel signals of the r1 portion and the l2 portion by the following equation to reduce the apparent pixel pitch to ½ and match the pixel pitch of the c1 portion and the c2 portion.

[0046]

[Formula 1] Here, I (n) is the n-th signal amount before interpolation processing, I ′
(M) is the m-th signal amount after interpolation processing. The signal images after the interpolation processing are shown in (g) and (h) of FIG. This makes the pixel pitch uniform and enables correlation calculation.

In this way, the pixel pitches of the r1, c1 part and the c2, l2 part are processed to be uniform, and step # 5 is performed.
Move to 04. Then, in this step # 504, the distance to the subject is calculated by detecting the phase difference between the signal images corrected and interpolated in the above steps # 502 and 503, the focus lens position is determined, and a series of distance measurement is performed. The operation ends.

As described above, in the distance measuring device as shown in FIG. 1, in the macro photography mode (when the subject is in a close range), the received light image is discontinuous at the pixel pitch discontinuous portion. Distance correction is enabled by correcting distortion and interpolating so that the pixel pitch becomes uniform.

In the present embodiment described above, the passive type device is described, but the present invention can also be applied to an active type distance measuring device having a light projecting means.

Further, while the signal peak is detected and controlled when the signal is accumulated in the light receiving sensor, the signal may be accumulated by other control methods. Further, although the discontinuity and the distortion of the signal image are corrected by the ratio of the pixel area of the light receiving sensor, they may be corrected by other methods.

According to the above embodiment, the pixel pitch in the central portion of the light receiving sensor is made smaller than the pixel pitch in the peripheral portion, so that the accuracy in distance measurement of the subject C in the center is improved and the peripheral portion is improved. For the subjects L and R, the calculation time can be shortened, and the calculation time as a whole can also be shortened.

Further, when the subject is located at a close range instead of the normal shooting distance, specifically, in the macro shooting mode, as shown in FIG. 4, the light is received over the portions having different pixel pitches. Since an image is formed, the received light signal is discontinuous or distorted at the boundary where the pixel pitch changes.
Therefore, as described with reference to FIG. 6, since the discontinuity and distortion of the signal image at the boundary between the central portion and the peripheral portion of the light receiving sensor are corrected, proper distance measurement is possible.

[0053]

As described above, according to the first aspect of the present invention, the distance measurement is performed accurately for the central object among the objects positioned in different measurement fields, and the calculation required for the distance measurement is performed. It is possible to provide a multi-point distance measuring device that can significantly reduce the time.

Further, according to the invention described in any one of claims 2 to 4, the distance measurement is performed accurately for the central object among the objects positioned in the different measurement visual fields, and the calculation time required for the distance measurement is significantly increased. Can be shortened to
Even when the subject distance is measured by combining the image signals output from the central part and peripheral part with different photoelectric conversion element pitches, the discontinuity and distortion of the image signal due to the difference in photoelectric conversion element pitch are corrected. It is possible to provide a multi-point distance measuring device capable of performing distance measurement by using the above method.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a main part of a multipoint distance measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a series of operations of the multipoint distance measuring apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram for explaining a pixel pitch of a light receiving sensor of the multi-point distance measuring apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating a relationship between a subject distance and a light receiving position in the embodiment of the present invention.

FIG. 5 is a flowchart showing an operation in a macro mode according to the embodiment of the present invention.

FIG. 6 is a diagram showing a light reception signal before correction and a light reception signal after correction in the macro photography mode in the embodiment of the present invention.

FIG. 7 is a configuration diagram showing a conventional passive distance measuring device.

[Explanation of symbols] 101, 102 First and second light receiving sensors 103, 104 First and second light receiving lenses 105 (L) subject 106 (C) Subject 107 (R) Subject r1, c1, l1 Area of each light receiving sensor r2, c2, l2 Area of each light receiving sensor

Claims (4)

[Claims] 1. A pair of light receiving means for receiving light from respective subjects located in different measurement fields of view, and a phase difference calculating means for calculating a phase difference of image signals output from the pair of light receiving means. In the multi-point distance measuring device that measures the distance of the subject located in each measurement visual field from the calculation result of the phase difference calculating means, the light receiving means has a plurality of photoelectric conversion elements arranged at a predetermined pitch. , The photoelectric conversion element pitch in the central portion of the light receiving means is configured to be smaller than the photoelectric conversion element pitch in the peripheral portion, and among the subjects located in each of the measurement visual fields by the image signal output from the central portion of the light receiving means. It is characterized in that the distance to the central object is measured, and the distance to the peripheral object among the objects located in the respective measurement visual fields is measured by the image signal output from the peripheral portion of the light receiving means. Point distance measuring device. 2. A pair of light receiving means for receiving light from respective subjects located in different measurement fields of view, and a phase difference calculating means for calculating a phase difference of image signals output from the pair of light receiving means. In the multi-point distance measuring device that measures the distance of the subject located in each measurement visual field from the calculation result of the phase difference calculating means, the light receiving means has a plurality of photoelectric conversion elements arranged at a predetermined pitch. , The photoelectric conversion element pitch in the central portion of the light receiving means is configured to be smaller than the photoelectric conversion element pitch in the peripheral portion, and an image signal output from the central portion of the light receiving means is applied to each of the subjects located in each measurement visual field. A first distance measuring process for measuring the distance of the central object and measuring the distance of the peripheral object among the objects positioned in the respective measurement visual fields by the image signal output from the peripheral portion of the light receiving means. And a second distance measurement processing function for measuring the subject distance by an image signal obtained by combining an image signal output from the central portion of the light receiving unit and an image signal output from the peripheral portion of the light receiving unit. A multipoint distance measuring apparatus, wherein when the image signals are combined by the second distance measuring process, the discontinuity and the distortion of the image signals due to the difference in the photoelectric conversion element pitch between the central portion and the peripheral portion are corrected. 3. The second distance measuring process is executed only in a predetermined photographing mode of the camera.
The multi-point distance measuring device described in. 4. The multi-point distance measuring apparatus according to claim 3, wherein the predetermined shooting mode of the camera is a macro shooting mode.