JP2001154083A - Range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a range finder capable of improving the range finding accuracy. SOLUTION: This range finder is provided with a range finding sensor 36 for finding a range in plural range finding areas, and a range finding calculation is executed by a CPU 21, based on a pair of range finding data obtained by the range finding sensor 36, and first the effectiveness of the obtained range finding value is determined. Next, the range finding value at the closest range is detected out of the effective range finding values, and the range finding value of the highest reliability is selected from among the detected value on the closest range side and the range finding value on the long range side whose difference from the range finding value on the closest range side is smaller than a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring apparatus capable of measuring a plurality of distance measuring areas.

[0002]

2. Description of the Related Art In recent years, various types of distance measuring devices capable of measuring distances in a plurality of distance measuring areas have been developed. Focusing is performed on the subject based on the distance measurement value of the distance measurement area selected manually or manually, and shooting is performed.
When the user causes the camera to automatically select the ranging area, the determination is made on the assumption that the object desired by the user is present closest to the camera among the objects existing in the ranging area. In some cases, the validity of the measured distance value is determined, and the closest measured distance value is selected from the effective measured distance values. However, the subject desired by the user is not always included in the ranging area where the closest ranging value is obtained, so that the desired subject may be out of focus.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a distance measuring apparatus capable of improving the distance measuring accuracy.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a distance measuring means for measuring distances for a plurality of distance measuring areas,
The reliability measuring means for determining the validity of the measured distance value measured by the distance measuring means, and determining the reliability of the measured distance value determined to be effective,
Among the distance measurement values determined by the reliability measurement means to be effective, a difference between the closest distance measurement value and the closest distance measurement value is smaller than a predetermined value. Selecting means for selecting the most reliable distance measurement value from the values. Further, the present invention may be configured such that the predetermined value is changed in accordance with the distance to the subject having the closest distance measurement value. The distance measuring unit projects the images of the objects in the plurality of distance measuring areas onto the corresponding light receiving areas of the pair of line sensors, and outputs the image in pixel units from the pair of light receiving areas. The calculation for obtaining the sum of the absolute values of the differences between the signals output from one of the light receiving areas and the signal output from the other light receiving area for each pixel is performed based on the signal output from the one light receiving area. As described above, the signal output from the other light receiving area is executed while being shifted in pixel units, a correlation function relating to the shift amount and the sum is obtained, and further, a first value in which the value of the correlation function is minimized in pixel units A second value that is the second smallest is obtained, a third value and a fourth value sandwiching the first value and the second value are obtained, and a first value and a fourth value that are close to the first value are obtained. 3 to the first straight line passing through the second value and the second value. Seeking have intersection of the second straight line passing through the fourth value, determine the spacing of the image of the subject of the respective distance measuring area from a shift amount corresponding to the intersection point,
It is preferable that the reliability measuring means includes a calculating means for calculating the distance to the subject based on the interval between the images, and the reliability measuring means includes two straight lines set by the calculating means to detect the distance measurement value. It is desirable to determine the steepness of the slope and determine reliability based on the steepness. The steepness of the inclination of the two straight lines is, in other words, a small angle between the two straight lines set by the arithmetic means to detect the interval between the images. The smaller the angle, the steeper the angle. The reliability measuring means determines that the steeper the average value of the slopes of the two straight lines, the higher the reliability. According to the above configuration, a more reliable ranging value can be obtained, and the ranging accuracy can be improved.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 to 3 are external views showing an embodiment of a lens shutter camera to which the present invention is applied. As shown in FIG. 1, a camera body 1 of this lens shutter camera includes a zoom lens 2 on the front, and an A
An auxiliary light projecting window 3 for F, a passive AF light receiving window 4, a finder window 5, and a photometric window 6 are provided. In addition, these windows 3-6
In the rear camera body 1, an AF auxiliary light source, a distance measurement sensor, a finder optical system,
Photometric sensors are arranged respectively.

A release button 8 is provided on the upper decorative plate 7 of the camera body 1. The release button 8 is linked with the photometry switch SWS and the release switch SWR. The photometry switch SWS is turned on when the release button 8 is half-pressed, and the release switch SWR is turned on when fully pressed. Camera body 1
A main switch lever 10 for turning on / off the power is provided at the center of the rear surface of the zoom lens. Is provided. The zoom lens lever 9 is linked with the tele switch SWT and the wide switch SWW,
When the zoom lens lever 9 is tilted to the tele side, the tele switch SWT is turned on, and when the zoom lens lever 9 is tilted to the wide side, the wide switch SWW is turned on. In addition, a green lamp 11 is provided near the eyepiece window 12 on the back of the camera body 1 to notify the result of distance measurement by lighting or blinking.

Next, the configuration of the control system of the camera body 1 will be described in more detail with reference to the block diagram shown in FIG. The CPU 21 has a built-in ROM in which programs related to the functions of the camera are written and a RAM in which various parameters for control or calculation are temporarily stored, and a control means for generally controlling the operation of the camera body 1. In addition to functioning as a reliability measure,
It also has a function as changing means.

The CPU 21 includes, as switches, a main switch SW interlocked with the main switch lever 10.
M, tele switch SW linked to zoom lens lever 9
T, the wide switch SWW, and the photometric switch SWS and the release switch SWR linked to the release button 8 are connected. When the main switch SWM is turned on by turning on the main switch lever 10, the CPU 21
Starts power supply to a peripheral circuit connected to each input / output port using the battery 23 as a power supply, and executes a process corresponding to the operated switch. When the tele switch SWT or the wide switch SWW linked to the zoom lever 9 is turned on, the CPU 21 drives the zoom motor 30 via the zoom lens drive circuit 29 to cause the zoom lens 2 to perform tele zoom or wide zoom. Zoom motor 30
When the power is off, the lens barrel of the zoom lens 2 is driven to a storage position where the lens barrel fits within the external appearance of the camera body 1, and when the power is on, the zoom lens 2 is driven until the zoom lens 2 moves to the wide end position. The focal length of the zoom lens 2 is detected by a zoom code input circuit 43.

When the release button 8 is half-pressed and the photometric switch SWS is turned on, first, the CPU 21 obtains the subject brightness via the photometric circuit 37. The photometric circuit 37 is provided with a photometric sensor (not shown), receives the subject light incident from the photometric window 6 with the photometric sensor, and outputs a photometric signal corresponding to the subject brightness to the CPU 21. CPU2
1 calculates an appropriate shutter speed and an appropriate aperture value based on the obtained subject luminance and the ISO sensitivity input via the DX code input circuit 45, and the like. DX code input circuit 4
5 reads the DX code written in the patrone of the film loaded in the camera body 1,
This is a circuit that outputs information such as the number of shots to the CPU 21.

The CPU 21 receives the distance measurement data from the distance measurement circuit 35, executes a distance measurement operation based on the input distance measurement data, obtains a distance measurement value, and obtains a distance measurement value satisfying a predetermined condition described later. Can be selected, the focus motor 32
Is driven through the focus drive circuit 31, and the green lamp 11 is turned on. When a distance measurement value that satisfies the predetermined condition cannot be selected, the green lamp 11 is blinked to notify a distance measurement error and alert the user.

The distance measuring circuit 35 is a circuit for detecting the focus state of the object included in each of the distance measuring areas, and has a distance measuring sensor 36 for receiving the light beam of the object, converting the light into electrical distance measurement data, and outputting the data. are doing. As shown in FIG. 5, the distance measuring sensor 36 divides the subject light beam by a pair of separator lenses (imaging lenses) 36a and receives the light on a pair of line sensors 36b including an A sensor and a B sensor. The pair of separator lenses 36a form a pair of subject images on the line sensor 36b at intervals according to the subject distance,
Although not shown in detail, the line sensor 36b has a large number of photoelectric conversion elements (light receiving elements). Each of the photoelectric conversion elements receives a subject luminous flux, performs photoelectric conversion, and integrates (accumulates) the photoelectrically converted charge. , And sequentially outputs the integrated charges as a signal (distance measurement data) for each pixel. The distance measuring circuit 35
A monitor sensor (not shown) that controls the integration time of the line sensor 36b according to the subject brightness is provided. The CPU 21 detects the output of the monitor sensor and controls the integration time of the line sensor 36b, that is, the integration end. In the present embodiment, 5
The distance measuring areas E [0] to E [4] are set. C
The PU 21 includes a pair of line sensors 36a and 36b on which images of the subjects E [0] to E [4] are formed in each ranging area.
The distance between the subject images is obtained based on the distance measurement data output from each of the light receiving areas e [0] to e [4], and the distance to the subject is obtained. FIG. 7 shows five distance measurement areas E [0].
E [4] and the light receiving area e [0] of one of the line sensors
The relationship with e [4] was shown.

When the brightness of the subject is low, or when the contrast of the subject is low, the AF auxiliary
1 is a circuit for irradiating a contrast pattern toward a subject under the control of the CPU 21 when it is determined.

When the release button 8 is fully depressed and the release switch SWR is turned on, the CPU 21 operates the aperture control circuit 25 based on the calculated appropriate aperture value to narrow down the aperture of the zoom lens 2 and based on the shutter speed. A shutter motor 34 is driven via a shutter control circuit 33 to expose the image. When the exposure is completed, the CPU 21 inputs a film feed signal through the film feed signal input circuit 41 and operates the film feed motor 28 via the film feed circuit 27 to wind up the film by one frame. When there is no amount, the film feeding circuit 27
, The film feed motor 28 is operated to rewind the film.

The main components of the camera have been described above. The camera has a self-lamp for displaying a self-timer operation,
A known device such as a flash device for emitting a flash under the control of the CPU 21 and an LCD display panel for displaying various information is provided.

FIG. 6 shows an outline in which the CPU 21 selects a distance measurement value in the distance measurement processing. In the figure, the vertical axis represents the reliability of the distance measurement value, and the horizontal axis represents the distance to the subject. CP
U21 performs a distance measurement operation based on each distance measurement data of each of the distance measurement areas E [0] to E [4], and performs a distance measurement value SE [0] to S.
E [4] is determined, and its validity and reliability are determined. Although details of the determination of the validity and the reliability will be described later, in FIG. 6, a default range of the reliability in which the CPU 21 determines that there is no reliability is indicated by hatched portions, and the obtained distance measurement values SE [0] to SE [4] is represented by a circle.

Next, the CPU 21 detects a distance measurement value on the closest distance side (hereinafter, referred to as a "nearest distance measurement value"). In the present embodiment, the image interval of the subject image formed on the light receiving area corresponding to each distance measurement area is detected, and the image interval is used as a distance measurement value. Therefore, since the distance measurement value becomes larger as the distance becomes shorter, the CPU 21 detects the largest distance measurement value as the closest distance measurement value. In FIG. 6, the distance measurement value SE is shown.
[2] is detected as the closest distance measurement value. When the latest distance measurement value is detected, the CPU 21 next determines the distance measurement value of the subject located farther than the subject for which the latest distance measurement value has been obtained, but the difference is smaller than the predetermined value L ( Less than,
It is called "short distance range". ) Is detected. In FIG. 6, the short distance range is indicated by a shaded portion.

Then, the CPU 21 selects the most reliable distance measurement value within the short distance range. In FIG. 6A,
Since only the distance measurement value SE [2] is included in the short distance range, the distance measurement value SE [2] (black circle in the figure) is selected. FIG. 6 (b)
Now, the distance measurement value SE [2] and the distance measurement value SE
The two points of [1] are included. In this case, the distance measurement value SE [2]
Is a recent ranging value, but a more reliable ranging value SE
Select [1] (in the figure; black circle). When there are a plurality of subjects, the subject desired by the user is not always located closest to the camera, so that
This is for selecting the most reliable distance measurement value on the short distance side and improving the distance measurement accuracy. If the predetermined value L is constant, the short distance range becomes too wide when the latest distance measurement value is small, that is, when the distance to the subject is long. In order to prevent this, in the present embodiment, the predetermined value L is changed in accordance with the subject distance of the closest distance measurement value, and the short distance range is limited.

Next, a description will be given of the calculation of the distance measurement and the determination of the validity / reliability of the distance measurement value. First, the CPU 21 obtains a correlation function f (N) based on a pair of distance measurement data. The correlation function f (N) is obtained by superimposing the A sensor data and the B sensor data of the line sensor 36b to obtain the sum of the absolute values of the differences for each pixel data (this is referred to as “correlation value”). This is a function obtained by executing the B sensor data while shifting it by one pixel on the basis of the sensor data, and is a function relating to the shift amount and the correlation value. The CPU 21 detects the minimum value of the correlation function f (N), and detects the shift amount of the B sensor data with respect to the A sensor data when the minimum value is obtained, that is, detects the image interval as the distance measurement value. Since a correlation value can be obtained from the correlation function f (N) only for each photoelectric conversion element of the line sensor 36b, interpolation calculation is usually further performed based on the obtained correlation function f (N). Execute to find a more accurate minimum value. FIG. 8 shows an outline of obtaining a minimum value by interpolation calculation from the correlation function f (N). In the interpolation calculation, the first point (x1, y1) at which the correlation value is the smallest for each photoelectric conversion element and the second point (x
2, y2), and further, the obtained two points (x1,
y1), a third point (x0, y0) sandwiching (x2, y2)
And a fourth point (x3, y3), and a minimum value is determined using the total of the four points. That is, the first point (x1, y1) and the third point (x0, y1) close to the first point (x1, y1)
y0), a first straight line passing through a second point (x2, y2) and a second point passing through a fourth point (x3, y3) close to the second point.
The intersection (x, y) of this straight line is obtained, and the X coordinate of this intersection is obtained as the image interval, that is, the distance measurement value. In the interpolation calculation, the slopes D1 and D2 of these two straight lines are obtained. In addition,
In the figure, the X coordinate indicates the shift amount (interval) between the A sensor data and the B sensor data, and the Y coordinate indicates the total sum (correlation value) of the absolute values of the differences.

When the distance measurement values are obtained, the CPU 21 first determines the validity of each distance measurement value. Whether the distance measurement value is valid or not is determined by the number of the minimum values of the correlation function f (N), the correlation function f
The determination is made based on the magnitude of the minimum value of (N). CPU
The case where it is determined that 21 is not valid is, for example, a case where there are two or more minimum values of the correlation function f (N) or a case where the value of the minimum value is larger than a predetermined value. . Next, the CPU 21 determines the reliability of each distance measurement value determined to be valid. The reliability of the distance measurement value is determined by the absolute value of the slope of the two straight lines obtained by the interpolation calculation (FIG. 8).
This is referred to as “the slope of the correlation function f (N)”. ) It is determined based on D1 and D2. Slope D1, D2 of correlation function f (N)
Is determined by: D1 = | (y1-y0) / (x1-x0) | D2 = | (y3-y2) / (x3-x2) | The CPU 21 increases the reliability of the distance measurement value as the average value of the slopes D1 and D2 increases. Judgment is high. Note that the reliability may be determined by comparing the obtained minimum values with each other. However, the determination based on the steepness of the slope of the correlation function f (N) as in the present embodiment improves the detection accuracy. Excellent and desirable.

Next, the operation of the camera body 1 will be described in more detail with reference to the flowcharts shown in FIGS. FIG. 9 is a flowchart relating to the photographing process, which is executed when the photometric switch SWS is turned on. When this process is started, first, a photometric process is executed to obtain a subject luminance, and a distance measuring process is executed to obtain a distance measurement value (S11, S13). The details of the ranging process will be described later, but the ranging value is calculated from the ranging data of each ranging area,
This is a process of selecting a ranging value satisfying a predetermined condition from each ranging value, and moving a focusing lens (not shown) based on the selected ranging value.

After the distance measurement process, it is checked whether a distance measurement error flag is set (S15). When the distance measurement error flag is set, that is, when a distance measurement value satisfying a predetermined condition cannot be selected in the distance measurement processing, the green lamp 11 blinks to call the user's attention, and the AE calculation processing is executed. To set an appropriate shutter speed and aperture value (S15; Y, S19, S21). When the distance measurement error flag is cleared, the green lamp 11 is turned on and the AE
The arithmetic processing is executed (S15; N, S17, S21).

Then, it is checked whether the photometric switch SWS is on (S23). Photometric switch S
If the WS is not on, the process returns (S23; N). If the photometric switch SWS is on, it is checked whether the release switch SWR is on (S23; Y, S25). If the release switch SWR is not turned on, the process returns to S23, and enters a release command standby state (S25; N, S23). When the release switch SWR is ON, the green lamp 11 is turned off, the aperture control circuit 25 is operated based on the calculated appropriate aperture value, the aperture of the zoom lens 2 is reduced, and the shutter control is performed based on the appropriate shutter speed. Circuit 33
(S25; Y, S27, S29).
After the exposure control process is completed, the film feed motor 28 is operated via the film feed circuit 27 to wind up the film by one frame. If there is no remaining film, the entire film is rewound and returned (S31). .

FIG. 1 shows the distance measuring process executed in S13.
This will be described in more detail with reference to the flowchart shown in FIG. In this process, first, it is checked whether or not the subject luminance obtained in S11 is equal to or more than a predetermined value (S51). When the subject brightness is lower than the predetermined value, auxiliary light is emitted at predetermined intervals via the AF auxiliary light emitting device 39 for a predetermined time (S51; Y, S53), and the subject brightness is equal to or higher than the predetermined value. Sometimes, the auxiliary light is not emitted (S51; N),
The integral values obtained by the A sensor and the B sensor of the line sensor 36b receiving the subject light, photoelectrically converting and integrating the subject light are input as the A sensor data and the B sensor data (S55).

The CPU 21 calculates a correlation function f (N) based on the input A-sensor data and B-sensor data to execute a distance measurement operation for obtaining a distance measurement value (S57). When the distance measurement value is obtained, a distance measurement value selection process is executed next (S5).
9). Although the details will be described later, the ranging value selection process is a process of detecting and selecting the most reliable ranging value within a short distance range from the determined ranging values.

As a result of executing the ranging value selection processing (S59), if the most reliable ranging value within the short range can be selected, the ranging error flag is cleared and the selected ranging value is used. LL data (the number of pulses for driving the focus motor 30) is calculated, the focus motor 30 is driven based on the obtained LL data, a lens driving process for moving a focusing lens (not shown) to a focusing position is executed, and the process returns ( S61; Y, S63, S65, S6
7). If a distance measurement value cannot be selected, a distance measurement error flag is set and the routine returns (S61; N, S6).
9).

The ranging value selection processing executed in S59 will be described in more detail with reference to the flowchart shown in FIG. 11 and FIG. 6B. In this processing, first, an effective ranging value determined to be valid is extracted from the obtained ranging values, a nearest distance ranging value is detected from the determined effective ranging values, and the detected nearest ranging value is detected. The most reliable distance measurement value is selected from the value and the distance measurement values included in the predetermined short distance range.

In this process, an initial value 0 is set for the variables i and j (S101), and an effective distance measurement value extraction loop process is executed. However, the variable i is the distance value register S
The address number of the distance measurement value stored in E
Is the total number of distance measurement values stored in the effective distance measurement value register S.

When entering this loop processing, first, the i-th distance value SE [i] stored in the distance value register SE.
Is checked (S103). CPU2
1 determines that the correlation function f (N) is not valid when there are two or more minimum values of the correlation function f (N) from which the distance measurement value is obtained, or when the minimum value is larger than a predetermined value (see FIG. 6). Distance value SE [i]
Is valid, the effective distance value register S
Is stored in the memory, and 1 is added to the variable j.
The process proceeds to S107 (S103; Y, S105). Distance value S
When it is determined that E [i] is not valid (S103;
N), skip S105 and proceed to S107. Then, 1 is added to the variable i (S107), and the variable i is changed to the variable k.
It is checked whether it is smaller than (S109). The variable k is the total number of distance measurement areas. In this embodiment, since five distance measurement areas are provided, 5 is stored in the variable k. If the variable i is smaller than the variable k, the process returns to S103 to check the next distance value SE [i],
The above processing is repeated (S109; Y, S103). By this processing, only the effective distance measurement value can be extracted from the obtained distance measurement values. In the case of FIG. 6B, the distance measurement values SE [0] to
Four of SE [3] are determined to be valid, and the distance measurement value SE is determined.
[0] to SE [3] are stored as effective distance measurement values S [0] to S [3]. At this time, the total number 4 of the distance measurement values determined to be valid is stored in the variable j.

When the variable i becomes equal to or larger than the variable k, and when the variable i becomes 5 in the present embodiment, the above check is performed for all the distance measurement values stored in the memory. Is checked to see if it is 0 (S10
9; N, S111). When the variable j is 0 (S1
11; Y), since nothing is stored in the effective distance measurement value register S, the process returns. In this case, it is determined that there is no Ef distance measurement value in S61 after the return. If the variable j is not 0, it is checked whether the variable j is 1 (S111; N, S113). When the variable j is 1, only the effective distance measurement value S [0] is stored in the effective distance measurement value register S.
The effective distance measurement value S [0] is stored in data, and the process returns (S113; Y, S115). In this case, it is determined that the Ef distance measurement value exists in S61 after the return.

When the variable j is not 1 (S113;
N), the distance measurement value SE stored in the effective distance measurement value register S
Since there are two or more [i], the effective distance value S [0] is first set to the nearest distance value sdata in order to select the nearest distance value sdata from the closest distance value. The memory is set, the variable h is set to 1, the variable dir is set to 0 (S117), and the closest distance measurement value detection loop processing is executed. However, the variable h is the address number of the effective distance value register S, the variable dir is the address number of the effective distance value S [h] stored in the latest distance value sdata, and the variable j is the effective distance value register S Is the total number of distance measurement values stored in the memory. In the present embodiment, the line sensor 36b
Since the upper image interval is detected as a distance measurement value, the distance measurement value on the short distance side has a larger value.

In this loop processing, first, it is determined whether or not the value of the latest distance measurement value sdata is smaller than the value of the effective distance measurement value S [h] stored in the address number h of the effective distance measurement value register S. Check (S119). When the latest distance measurement value sdata is smaller than the effective distance measurement value S [h] (S119; Y), the effective distance measurement value S [ h] is overwritten, the variable h is stored in the variable dir so that the effective distance measurement value S [h] stored in the latest distance measurement value sdata can be identified (S121), and the process proceeds to S123. The latest distance measurement value sdata is the effective distance measurement value S [h].
If it is equal to or greater than (S119; N), the nearest distance measurement value s
Since data is on the short distance side, S121 is skipped and the process proceeds to S123. Then, 1 is added to the variable h (S1
23) It is checked whether the variable h is smaller than the variable j (S125). When the variable h is smaller than the variable j, the effective distance measurement value S for which the check in S119 is not performed is performed.
Since there is [h], the process returns to S119 (S125; Y).
By this processing, the effective distance measurement value having the largest value can be finally detected as the latest distance measurement value sdata. In the case of FIG. 6B, the effective distance measurement value S [2] (the distance measurement value SE [2]) is stored as the nearest distance measurement value sdata, and the address number 2 is stored in the variable dir.

When the variable h is equal to or larger than the variable j, the variable h is reset to 0, and the short distance range setting process is executed (S125; N, S127, S129). As shown in FIG. 12, the short distance range setting process sets a predetermined value L that regulates the short distance range according to the magnitude of the value of the latest distance measurement value sdata, that is, the distance to the subject. Is a process for restricting the value from becoming too wide.
In the present embodiment, the nearest distance measurement value sdata is divided into three distance ranges, and the predetermined value L is set to be larger as the distance measurement value included in the range on the short distance side. In FIG. 12, A <B, 0 <a <b <c, where A <B and 0 <a <b <c, constants A and B for setting the distance range of the latest distance measurement value sdata, and constants a, b and c for setting the predetermined value L. .

When entering this process, first, the nearest distance measurement value s
It is checked whether the value of data is smaller than the constant A (S201). When the latest distance measurement value sdata is smaller than the constant A, since the latest distance measurement value sdata is slightly longer, the smallest constant a is set to the predetermined value L and the process returns (S201; Y, S203). If the latest distance measurement value sdata is equal to or larger than the constant A, it is checked whether it is smaller than the constant B (S205). When the latest distance measurement value sdata is smaller than the constant B, since the latest distance measurement value sdata is relatively short, the predetermined value L
Is set to a constant b, and the process returns (S205; Y, S2
07). If the latest distance measurement value sdata is equal to or larger than the constant B, the closest distance measurement value sdata is closer to the short distance, so the largest constant c is set to the predetermined value L and the process returns (S205; N, S209). .

When entering the Ef distance detection value detection loop processing, first, it is checked whether or not the variable dir and the variable h match (S131). When the variable dir and the variable h match, the effective distance value S [h] to be compared in S133 or S137 is the same as the effective distance value stored as the latest distance value sdata.
Skip to S139 and proceed to S141 (S131;
Y). When the variable dir and the variable h do not match (S
131; N), it is checked whether or not the difference between the latest distance measurement value sdata and the effective distance measurement value S [h] is smaller than the predetermined value L set in S129 (S133). When the difference between the latest distance measurement value sdata and the effective distance measurement value S [h] is equal to or greater than the predetermined value L (S133; N), the effective distance measurement value S [h].
Are not included in the short distance range, so that S135 to S1
The process skips 39 and proceeds directly to S141. The difference between the latest distance measurement value sdata and the effective distance measurement value S [h] is a predetermined value L
If smaller (S133; Y), the effective distance value S
Since [h] is included in the short distance range, a reliability calculation process is executed next to determine the high reliability of the latest distance measurement value sdata and the effective distance measurement value S [h]. (S13
5).

In the reliability calculation processing, as shown in FIG. 13, in the correlation function fs (N) of the ranging area where the latest distance measurement value sdata is obtained, the slope D of the correlation function fs (N) is obtained.
An average value ds of s1 and Ds2 is obtained (S301). Further, the correlation function f of the ranging area where the effective ranging value S [h] is obtained.
h (N), the slope Dh1, of the correlation function fh (N)
An average value dh of Dh2 is obtained (S302) (see FIG. 8). The average value ds or dh of the slope of the correlation function fs (N) or fh (N) can be said to have higher reliability as the average value ds or dh increases.

Then, the reliability dh of the effective distance measurement value S [h] is obtained.
Is higher than the reliability ds of the latest distance measurement value sdata (S137). Effective distance value S [h]
Is the reliability ds of the nearest distance measurement value sdata
If it is higher than the effective distance value S [h], the latest distance value sdata is added to obtain a more reliable distance value.
And the process proceeds to S141 (S137; Y, S13
9). When the reliability dh of the effective distance measurement value S [h] is equal to or less than the reliability ds of the latest distance measurement value sdata, S13.
Skip to step S141 and proceed directly to step S141 (S137;
N).

Then, 1 is added to the variable h (S141).
Check whether variable h is smaller than variable j (S
143). If the variable h is smaller than the variable j, S133
Alternatively, since there is an effective distance measurement value S [h] for which the check in S137 has not been performed, the process returns to S129, and the above processing is repeated (S143; Y, S129). When the variable h is equal to or larger than the variable j, the process returns (S143;
N). In this case, it is determined that the Ef distance measurement value exists in S61 after the return. In the case of FIG. 6B, the effective distance value S [1] (the distance value SE [1]) in addition to the latest distance value sdata (the distance value SE [2]) in the short distance range. Since it is included, the more reliable effective distance value S [1] is overwritten and stored as the latest distance value sdata, and this effective distance value S [1] is finally selected.

As described above, in this embodiment, the distance measurement is performed when the distance between the nearest distance measurement value sdata and the nearest distance measurement value sdata on the line sensor 36b is within the short distance range smaller than the predetermined value L. Since the most reliable distance measurement value is selected from the values, the distance measurement accuracy can be improved. Although the embodiment in which the present invention is applied to the lens shutter type camera has been described above, the present invention is of course not limited to this, and can be applied to a single-lens reflex camera and the like.

[0039]

As is apparent from the above description, according to the present invention, the difference between the closest measured distance value and the closest measured distance value among the measured distance values determined to be effective is described. Since the most reliable distance measurement value is selected from the distance measurement values on the long distance side smaller than the predetermined value, the distance measurement accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a front view of a lens shutter camera to which the present invention is applied.

FIG. 2 is a diagram showing a top view of the lens shutter camera.

FIG. 3 is a diagram showing a rear view of the lens shutter camera.

FIG. 4 is a block diagram showing one embodiment of a main configuration of a control system of the lens shutter camera.

FIG. 5 is a diagram showing an outline of a distance measuring sensor of the lens shutter type camera.

FIG. 6 is a diagram showing an outline of selecting a distance measurement value by the distance measurement processing of the lens shutter camera.

FIG. 7 is a diagram showing a relationship between a distance measurement area and a light receiving area on a line sensor.

FIG. 8 is a diagram showing an outline of obtaining a minimum value by interpolation calculation from a correlation function f (N).

FIG. 9 is a flowchart showing a photographing process of the lens shutter camera.

FIG. 10 is a view showing a flowchart relating to a distance measuring process of the lens shutter type camera.

FIG. 11 is a diagram showing a part of a flowchart relating to distance measurement value selection processing of the lens shutter camera.

FIG. 12 is a view showing a flowchart relating to a short distance range setting process of the lens shutter camera.

FIG. 13 is a view showing a flowchart concerning reliability calculation processing of the lens shutter camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera body 2 Zoom lens 9 Release button 21 CPU 25 Aperture control circuit 29 Zoom lens drive circuit 31 Focus drive circuit 35 Distance measurement circuit 36 Distance measurement sensor 36a Separator lens 36b Line sensor 37 Photometry circuit

Claims (4)

[Claims] 1. A distance measuring means for measuring a distance in a plurality of distance measuring areas, and a reliability for judging the validity of the measured distance value measured by the distance measuring means and determining the reliability of the measured distance value determined to be effective. The distance measurement value between the closest distance measurement value and the closest measurement value among the distance measurement values determined by the reliability measurement means to be valid. Selecting means for selecting the most reliable ranging value from the ranging values on the distance side. 2. The distance measuring apparatus according to claim 1, further comprising a change unit that changes the predetermined value in accordance with a distance of the subject having the closest distance measurement value. . 3. The distance measuring apparatus according to claim 1, wherein the distance measuring means projects images of the subject in the plurality of distance measuring areas onto corresponding light receiving areas of a pair of line sensors, respectively. Sensor means for outputting a pixel from each pair of light receiving areas, and a sum of absolute values of differences between pixels of a signal output from one light receiving area and a signal output from the other light receiving area of the pair of light receiving areas Is performed while shifting the signal output from the other light receiving region on a pixel-by-pixel basis with reference to the signal output from the one light receiving region to obtain a correlation function regarding the shift amount and the sum, A first value at which the value of the correlation function is the smallest in pixel units and a second value that is the second smallest are obtained, and a third value and a fourth value sandwiching the first value and the second value are obtained. And determine the first value and the value close to the first value. An intersection of a first straight line passing through a third value and a second straight line passing through the second value and a fourth value close to the second value is determined, and the measurement is performed based on the shift amount corresponding to the intersection. Calculating means for calculating the distance between the images of the subject in the distance area and calculating the distance to the subject based on the distance between the images, wherein the reliability measuring means includes the first straight line or the second line.
A steepness of the slope of at least one of the straight lines is obtained, and reliability is obtained based on the steepness. 4. The distance measuring apparatus according to claim 3, wherein the reliability measuring means obtains the steepness of the slope of each of the first straight line and the second straight line, based on an average value of the steepness. A distance measuring device characterized by seeking reliability.