JPH08327884A - Range-finding device - Google Patents

Abstract

PURPOSE: To provide a multiple range-finding device by which a reliable range- finding value is obtained and which hardly gets into a range-finding infeasible state. CONSTITUTION: This device is provided with a CPU 31 arithmetically calculating the range-finding value based on a pair of right and left video data groups obtained by an AF range-finding sensor 41, and the CPU 31 sets a reliability judging level at which the range-finding value is judged as effective or ineffective in two stages and selects the range-finding value from among range-finding values obtaining the reliability equal to or above the 2nd stage reliability judging level B lower than the 1st stage reliability judging level A when the range- finding value having the reliability equal to or above the level A can not be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive distance measuring device mounted on a camera or the like.

[0002]

2. Description of the Related Art A general passive distance measuring device mounted on a conventional camera divides a subject light flux into two by a splitting optical system, and divides a pair of subject light fluxes into a pair of left and right line sensors. An image is formed (focused) on one side and converted into electrical image data by each of the left and right line sensors, and distance measurement calculation is performed based on these image data, for example,
The correlation (coincidence) of the video data in the left and right distance measuring areas is evaluated while shifting the distance measuring areas, and the left and right image distances are obtained from the position of the distance measuring area where the best matching degree is obtained. A distance measurement value such as a subject distance or a defocus amount is obtained from the image interval. In a so-called multi-distance measuring device capable of measuring distances in a plurality of distance measuring areas, one distance measuring value that matches a predetermined condition is selected from a plurality of distance measuring values.

In the conventional multi-range distance measuring apparatus, the judgment as to the reliability and effectiveness of each range-finding value is made only based on the magnitude relationship with respect to a certain effectiveness judgment level. Therefore, if the judgment level is set high, the reliability will be high, but the probability that the reliability will not be obtained will be high, so it will be easy to fall into the state where distance measurement is impossible. There was a problem that the probability of

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the above-described conventional distance measuring devices, and an object of the present invention is to provide a multi-distance measuring device which is highly reliable and which is unlikely to fall into a distance measuring impossible state. .

[0005]

SUMMARY OF THE INVENTION An object of the present invention to achieve the above object is to provide a distance measuring sensor having a pair of line sensors provided with a plurality of light receiving means for photoelectrically converting subject light received by each and integrating and outputting image data. A distance measuring device comprising: a calculating means for calculating a distance measurement value based on a video data group of a plurality of distance measuring areas of the pair of line sensors; and a distance measuring area for each distance measuring area. A reliability judgment means for judging the reliability of the image data group, and one distance measurement value that matches a predetermined condition is selected from the distance measurement values of the distance measurement area judged to be reliable by the reliability judgment means. Distance measurement value selection means, the reliability determination means has a plurality of reliability determination levels, and the reliability is determined from the highest reliability determination level among the plurality of reliability determination levels. A group of video data above the reliability judgment level was obtained. Ranging area to determine the reliability of the image data group by the next higher reliability determination level when that did not exist, to have the features.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments. 1 and 2 are a front view and a rear view of an embodiment of a lens shutter camera incorporating a strobe to which the present invention is applied. A zoom lens 13 is provided in front of a camera body 11 of this lens shutter type camera, and a metering window 15, an AF auxiliary light projecting window 16, a viewfinder window 17, a passive AF light receiving window 18 and a strobe light emitting window 1 are arranged above the zoom lens 13.
9 is equipped. Although not shown, a photometric sensor, an AF auxiliary light projecting element, a finder optical system, a passive AF unit, and a stroboscopic light emitting section are respectively arranged in the rear camera body 11 of these windows 15 to 19 as well known. ing.

A release button 21 and a flash button 23 are arranged on the upper surface of the camera body 11.
The release button 21 is interlocked with the photometric switch SWS and the release switch SWR, and as is well known, the photometric switch SWS is turned on by half-pressing, and the release switch SWR is turned on by full-pressing. Further, a zoom lever 25 that can zoom the zoom lens 13 in the tele direction or the wide direction when the camera body 11 is tilted to the tele side or the wide side is provided on the upper rear surface of the camera body 11. This zoom lever 2
5 is teleswitch SWTELE and wide switch SWWI
In conjunction with DE, when the zoom lever 25 is tilted to the tele side or the wide side, the tele switch SWTELE and the wide switch SWWIDE turn on.

Further, on the front surface of the camera body 11, a self-lamp 2 that displays a self-timer operation and also functions as an exposure notice lamp for giving an advance notice of exposure during photographing.
7 are arranged. Further, a green lamp 28 and a red lamp 29 for displaying distance measurement and strobe information are provided near the eyepiece frame on the back surface of the camera body 11.

FIG. 3 is a block diagram showing a circuit configuration of the lens shutter type camera. The camera body 11 is provided with a microcomputer (CPU) 31 that controls general camera control such as automatic adjustment (AF) processing, automatic exposure control processing, film winding and rewinding processing. As the switches, a photometric switch SWS, a release switch SWR, a telezoom switch SWTELE, and a wide zoom switch SWWIDE are input to the CPU 31, and the CPU 31 turns on / off these switches.
Upon receiving the OFF operation, a predetermined process is executed.

The DX code reading circuit 33 reads the DX code relating to the ISO speed from the DX code of the film cartridge loaded in the camera body 11, and CP
Output to U31. The zoom code input circuit 35 detects the current focal length data of the zoom lens 13 via a zoom code plate (not shown) and outputs it to the CPU 31. The photometric circuit 37 includes a photometric sensor (not shown). The photometric signal received by the photometric sensor from the photometric sensor is received by the photometric sensor, and the photometric signal converted into a current or a voltage corresponding to the subject brightness is C
Output to PU31. The CPU 31 calculates the subject brightness Bv based on this photometric signal, and the subject brightness Bv
Then, the proper shutter speed Tv and the proper aperture value Av are calculated based on the ISO sensitivity Sv and the like read through the DX code reading circuit 33. AF auxiliary light projecting circuit 39
Is the CPU 31 when the subject brightness is low or when the CPU 31 determines that the contrast of the subject is low.
The subject is irradiated with a contrast pattern under the control of.

The AF sensor unit (passive AF circuit) 51, which also functions as a photographing distance detecting means, will be described in detail later, but receives a subject light flux and each includes a pair of two-dimensional video signals including a plurality of video signals. Is output. The CPU 31 which takes in the video signal performs A / D conversion for each video signal unit and stores it in the internal RAM. Then, the CPU 31 executes the distance measurement calculation based on the pair of stored video signals,
The focusing lens drive amount of the shutter / focus drive circuit 41 is calculated and driven.

Further, this camera has a release switch S
When the WR is turned on, the shutter speed is calculated based on the shutter speed Tv and the aperture value Av previously calculated by the CPU 31.
The shutter / diaphragm of the focus drive circuit 41 is driven.

When the tele-zoom switch SWTELE or the wide-zoom switch SWWIDE interlocked with the zoom lever 25 is turned on, the CPU 31 causes the zoom motor drive circuit 45 to operate.
The zoom motor M is driven through the zoom lens 13 to zoom (tele zoom, wide zoom). The zoom motor M drives the zoom lens 13 to a storage position where the lens barrel fits within the outer appearance of the camera body 11 (shortest) when the power is off, and to a wide end position when the power is on. The zoom lens 13 has a tele end macro function, and when a macro switch (not shown) is turned on, the zoom motor M is driven to drive the zoom lens 13 to a macro position beyond the tele end position. Lens positions such as the focal length and macro position of the zoom lens 13 are
It is detected by the zoom code input circuit 35.

The self lamp 27, the green lamp 28 and the red lamp 29 are driven by a lamp driving circuit. The above are the main components of this camera, but this camera
Known members such as a battery, a display panel for displaying various information, and a film winding / rewinding motor are provided.

FIG. 2 shows a more detailed block diagram of the AF sensor unit 51 of this embodiment. As shown in FIG. 4, the AF sensor unit 51 forms left and right images (condensing).
Lenses 52L, 52R, left and right line sensors 53L, 5
3R, left and right quantizers 54L and 54R, and controller 55
It has. Left, right imaging lens 52L, 52R, left,
The right line sensors 53L and 53R and the left and right quantizers 54L and 54R have the same configuration on the left and right and perform the same operation.

The light flux of the subject is composed of left and right imaging lenses 52L,
52R corresponding left and right line sensors 53L, 5
An image is formed on or after the 3R. The photodiodes of the left and right line sensors 53L and 53R that receive the subject light flux photoelectrically convert the received subject light, and generate an electrical signal (voltage or current) corresponding to the brightness in the left and right quantizers 54.
Output to L and 54R. Left and right quantizers 54L and 54R
Integrates each input electric signal, measures the time when the integrated value reaches a constant value, and stores each measured time. When the left and right quantizers 54L and 54R store the measurement time when all the electric signals reach a predetermined integral value, or when a predetermined time elapses before all the electric signals reach the predetermined integral value, After the memory for a predetermined measurement time is executed for the unprocessed photodiode, each measurement time data stored in memory is sequentially output to the CPU 31 as video data via the control unit 55. The CPU 31 stores each of these video data in memory. The image data of the photodiodes of the left and right line sensors 53L and 53R are also referred to as “bit data” below.

FIG. 6 shows the relationship between the distance measurement area used for multiple distance measurement and the line sensor. In this embodiment, 5
It has a plurality of distance measuring areas, which are central distance measuring areas m
c, left and right distance measuring areas ml and mr separated to the left and right thereof, a left intermediate distance measuring area mlc between the central distance measuring area mc and the left distance measuring area ml, and a central distance measuring area mc and right distance measuring area It consists of the right middle distance measuring area mrc between the distance and mr. Each ranging area m
Distance measuring areas (light receiving areas) M on the left and right line sensors 53L and 53R corresponding to c, ml, mr, mlc, and mrc.
C, ML, MR, MLC, MRC are shown in FIG.
Each of the left and right line sensors 53L and 53R of this embodiment is provided with 128 photodiodes as light receiving means, and bit data of 36 continuous photodiodes is used as each distance measuring area.

FIG. 8 shows the principle of distance measurement of the AF sensor unit 51. Left and right imaging lenses 52L, 52
The focal length of R is f. Left and right imaging lenses 52L, 5
The optical axes 2R are parallel to each other and are arranged at an optical axis interval B. Extension of each optical axis and left and right line sensors 53L, 53R
Let b1 and b2 be the intersections with and, the distance between points b1 and b2,
That is, the base line length is B. Where distance (subject distance)
The object P located at Lx has left and right imaging lenses 52L and 5L.
It is assumed that an image is formed at the points x1 and x2 on the left and right line sensors 53L and 53R by the 2R.
The interval between 1 and x2 is X. The distance between the points b1 and x1 is the image point distance XL, and the distance between the points b2 and x2 is the image point distance XR. The focal lengths of the left and right imaging lenses 52L and 52R are f. Here, according to the external light triangulation method, the following relationships are established. B: (XL + XR) = Lx: f Therefore, the subject distance Lx is obtained by the equation: Lx = B · f / (XL + XR) = B · f / (x−B). In this embodiment, the left and right imaging lenses 52
The focal length f of L and 52R, and the interval, that is, the base line length B
Is a fixed value. Therefore, the left and right line sensors 53
If the image point intervals XL, XR or the image point intervals x on L, 53R are obtained, the subject distance Lx can be obtained. In this embodiment, the image points x1 and x2 are detected, and the object distance Lx is obtained from the image distance X between them.

By the way, since the normal subject is not a point but a spread and a two-dimensional subject image is formed on the left and right line sensors 53L and 53R, the image points x1 and x2 are as described above.
Cannot be detected directly. Therefore, the left and right line sensors 53
The region where the degree of coincidence is highest when the pair of image data groups obtained in L and 53R are overlapped is detected while relatively shifting the overlapped image data group in the direction in which the photodiodes are arranged, and the position where the degree of coincidence is highest The interval of the image data group in is detected as the image point interval x.

An outline of the distance measurement calculation will be described with reference to FIG. The address of each photodiode of the left line sensor 53L is L (NL), and the address of each photodiode of the right line sensor 53R is R (NR). Then, when the left and right distance measuring areas (video data) used in the distance measuring calculation are set as shown in FIG. 8 in the entire light receiving area, an evaluation function f (N) indicating the degree of coincidence of the video data in the left and right distance measuring areas. Can be calculated by the following formula 1.

[0021]

[Equation 1]

However, N2 = N1 or N2 = N1 +
It is 10 <= N1 + N2 <= 24. Further, in this embodiment, W0 = 24. The correlation evaluation data obtained by this evaluation function f (N) becomes smaller as the degree of matching between the left and right video data groups becomes higher, and usually takes a minimum value. The minimum value of the evaluation function f (N) is obtained by the formula: f (N-1) ≤f (N) <f (N + 1). When the left and right video data groups completely match each other, 0, that is, the evaluation function f (N) = 0. When the evaluation function f (N) is obtained while shifting the distance measuring area in units of photodiodes as described above, the minimum value is obtained. Usually, this minimum value indicates the position with the highest degree of coincidence.
Further, this position is a position from the reference position of each distance measuring area of the left and right line sensors.

From this evaluation function f (N), the minimum value can be obtained only in the pitch unit of the photosensor, but the true minimum value may exist between the photosensors. FIG. 9 shows how a minimum value is obtained by interpolation calculation from the obtained evaluation function f (N). In this interpolation calculation, a section where a true minimum value is considered to exist is found, two straight lines intersecting in the section are set from the evaluation functions f (N) before and after, and the coordinates of the intersection are obtained. In the figure, two straight lines that pass through two points (x0, y0), (x1, y1) and two points (x2, y2), (x3, y3) that sandwich a section where a true minimum value exists The intersection point (x, y) is obtained, and the X coordinate of this intersection point is set as the image point position. In the figure, the X coordinate represents the position of the image point, and the Y coordinate represents the evaluation value. In this interpolation calculation, it can be seen that the accuracy is higher as the inclination of the two straight lines becomes steeper. In this embodiment, the reliability of the distance measurement data is determined based on this inclination.

FIG. 10 is a bar graph showing an example of the image data detected by the AF sensor unit 51, the image data of the light receiving area used in the distance measurement calculation, and the evaluation function f (N). In the figure, the vertical axis is the brightness and the horizontal axis is the arrangement of the left and right line sensors 53L and 53R. FIG.
In (A), left and right line sensors 53L and 53R
Of the whole area, (B) is the image data in the distance measuring area, (C) is the correlation evaluation data, and in each figure, (L) is the image data of the left and right line sensors 53L, 53R, ( R) is the left and right line sensor 53
This is video data regarding L and 53R. In the video data, the shorter the bar graph is, the brighter the image data is, and the shorter the bar graph is, the higher the degree of coincidence is.

The operation of the lens shutter type passive AF camera to which this embodiment is applied will be described in more detail with reference to the flow charts shown in FIGS. This process is C
It is executed by the CPU 31 based on the program stored in the internal ROM of the PU 31.

When a main switch (not shown) is turned on, this flow chart is entered, and various switches S are first set.
The on / off state of W is input (S101). And
Tele zoom switch SWTELE, wide zoom switch S
Check if WWIDE is on (S10)
3, S113). If the tele-zoom switch SWTELE is on, it has not reached the tele end and is not in the macro position, the tele-direction drive processing of the zoom motor M is executed and the process returns to S101 (S105, S107, S109, S1.
01), if it is in the macro position, the zoom lens 13 is moved to the tele end position and the process returns to S101 (S107, S1).
11, S101). In the tele-direction driving process, although not shown in detail, while the tele-zoom switch SWTELE is turned on, the zoom motor M is driven in the tele-direction until the zoom lens 13 reaches the tele end, and the zoom switch SW is turned on.
When is turned off or reaches the tele end, the zoom motor M is stopped and the process returns to S101.

If the wide zoom switch SWWIDE is on, the wide end has not been reached, and if it is not in the macro position, the wide direction drive processing of the zoom motor M is executed and the process returns to S101 (S103, S113, S115). , S
117, S119, S101), if in the macro position,
The zoom lens is moved to the telephoto end position and the process returns to S101 (S117, S121, S101).

Whether both the tele zoom switch SWTELE and the wide zoom switch SWWIDE are off (S1
03, S113), whether the tele end has been reached by turning on the tele zoom switch SWTELE (S103, S105, S113),
If the wide end has been reached by turning on the wide zoom switch SWWIDE (S103, S113, S115), it is determined whether or not the photometric switch SWS has changed from off to on. Check whether or not (S113, S123 or S11
5, S123). Then, if it is changed from off to on, the photographing processing subroutine is called (S123, S).
125). When the shooting process ends, the process returns to S101.

The photographing processing subroutine of S125 will be described in detail with reference to the flowcharts shown in FIGS. When you enter this subroutine, DX
The code reading circuit 33 is activated to input the ISO sensitivity, and the voltage of the battery is checked (S201, S203).
If the voltage of the battery is lower than the predetermined value, there is a possibility that normal image capturing processing may not be performed, so the process returns, and the process proceeds under the condition that the voltage of the battery is the normal value (S2).
05).

If the battery is normal, the passive AF circuit 51 is activated and distance data is input to obtain the subject distance (S207). The photometric circuit 37 is activated to input photometric data, the subject brightness is obtained, and the shutter speed and aperture value are calculated by a predetermined exposure calculation algorithm (S).
209, S211). Further, processing is performed to determine whether the distance measurement data is default (S213). Here, the default is 0 when proper ranging data is obtained, and the default is 1 when the contrast of the subject is low or when the blur amount is very large. The default value is 2 when the contrast is high but a plurality of local minimum values exist and proper distance measurement data cannot be obtained. This default check process will be described later with reference to FIG. In the case of a distance measurement error, the green lamp 28 is blinked to display that the distance measurement error has occurred (S215, S221). Even if the distance measurement error does not occur, the green lamp 28 blinks even when the subject distance is closer than the shortest subject distance that can be focused (S21).
5, S217, S221). When it is neither a distance measurement error nor a short distance, the green lamp 28 is turned on (continuously turned on) (S215, S217, S219).

Next, it is checked whether or not the strobe light is emitted. When the strobe light is emitted, a flashmatic (FM) operation is executed to obtain the aperture value Av (S225). When the FM calculation is completed, it is checked whether or not the charging is completed. If the charging is completed, the red lamp 29 is turned on, and if the charging is not completed, the red lamp 29 is made to blink and S
Proceed to 233 (S227, S229 or S231).
If you do not want the flash to fire, the above steps S227-S
The processing of 231 is skipped and the process proceeds to S233.

In S233, the states of the photometric switch SWS and the release switch SWR are input. Then, it waits for the release switch SWR to be turned on (S233,
S235, S237). The release switch SWR
If the photometric switch SWS is turned off before turning on, both the green lamp 28 and the red lamp 29 are turned off and the process returns (S237, S239).

When the release switch SWR is turned on,
The self lamp 27 is turned on to notify the release, and the green and red lamps 28 and 29 are turned off (S241). Then, the focus adjustment lens is driven, the self lamp 27 is turned off to perform the exposure process, the film winding / rewinding process is executed, and the process returns to the main routine (S243, S24).
5, S247, 249).

Referring to FIGS. 14 and 15, S207
The details of the distance measurement calculation process will be described. When entering the distance measurement calculation subroutine, first, various data relating to distance measurement are stored in the ROM,
It is read from RAM (S301). It is checked whether the photometric value, which is one of the read data, is less than or equal to the auxiliary light emission level. If the light emission value exceeds the auxiliary light emission level, the auxiliary light projecting circuit 39 is turned off (S303, S305). If there is, the auxiliary light projecting circuit 39 is turned on to start projecting the auxiliary light (S303, S307).

The integration end time (Time Up) is set, the flag i is set to 0, the AF sensor unit 51 is reset, that is, the integrated value is swept out, and the AF sensor unit 51 starts integration (S309, S31
1, S313). In the present embodiment, the AF sensor unit 51, which receives the reset signal from the CPU 31, executes the integration process, outputs the bit data of the left and right line sensors 53L and 53R to the CPU 31, and the CPU 31 stores them in the memory.

A distance measuring area used in distance measuring calculation is set (S315). That is, the right sensor start address NR and the left sensor start address NL to start reading the video data are set (see S401 and S403 in FIG. 16). Then, a predetermined number of video data starting from the address set in the distance measurement area is read, and data correction processing is performed to align the left and right video data levels (S317, S31).
9). Based on the corrected video data, the distance measurement value calculation is executed to calculate the subject distance (S321). The distance measurement value calculation includes calculation of the evaluation function f (N).

The above processing of S315 to S321 is executed for all of the five distance measuring areas MC, ML, MR, MLC and MRC (S323, S315 to S323).

After the distance measurement values (subject distances) have been calculated for all five distance measurement areas, distance measurement value selection processing is performed (S325). The selection process may be, for example, to select the closest distance measurement value.

When the distance measurement value selection processing is completed, 1 is set on condition that a normal distance measurement value is not obtained from all the distance measurement areas.
Auxiliary light is projected by the auxiliary light projecting circuit 39 only once, and S3
The ranging process of 13 to S323 is re-executed (S327 to S327).
333).

When normal distance measurement data is obtained from one or more distance measurement areas by the first processing of S313 to S331, or when the second processing of S333 and S313 to S331 is completed, all of the distance measurement data are again returned. It is checked whether or not the data in the distance measurement area is in error. If not all are in error, that is, if even one piece of normal data is obtained, the distance data is converted to lens drive (LL) data and the process returns. (S327, S335, S337). When the distance measurement values of all the distance measurement areas are in error, a distance measurement error flag is set and the process returns (S335, S33).
9).

FIG. 17 shows a subroutine relating to the data correction processing of S315. When you enter this subroutine,
First, the minimum value Lmin in the video data (left sensor data) for the left line sensor 53L and the minimum value Rmin in the video data (right sensor data) for the right line sensor 53R are detected (S501). Then, the difference D between the minimum values is calculated (S503). If the difference D is larger than 0, that is, if the left minimum value Lmin is larger, the left sensor data is corrected (S505, S507), and the difference D is less than 0. If so, that is, if the right minimum value Rmin is larger, the right sensor data is corrected (S505, S50).
9, S511), difference D is 0, left and right minimum values Lmin, R
If min is equal, nothing is executed and the process returns (S5).
05, S509). That is, the correction processing is performed by comparing the points having the highest brightness on the left and right line sensors.

The sensor correction processing in S507 and S511 will be described with reference to the subroutines shown in FIGS. These subroutines are processing for adding the difference D to the sensor data having the smaller minimum value and aligning the levels of the left and right sensor data. In the left sensor data correction, first, 0 is set to the variable i (S521). Next, the video data L (NL + i) at the address NL + i is replaced with the video data L (NL + i) -D, and 1 is added to the variable i (S523, S525). The above processing is repeated until the variable i becomes W0, that is, the distance measurement area is repeated (S527, S523 to S527).

Similarly in the right sensor data correction processing, 0 is set to the variable i (S531), the video data L (NL + i) at the address NL + i is replaced with the video data L (NL + i) -D, and 1 is added to the variable i. (S533, S53
5). The above processing is repeated until the content of the variable i becomes W0 (24 in this embodiment), that is, the distance measurement area is repeated (S537, S533 to S537). By the above left and right sensor data correction processing, the difference D is subtractively corrected for each image data corresponding to the left and right distance measurement areas.

FIG. 2 shows the distance measurement value calculation processing in S321.
This will be described with reference to the subroutine shown in 0. When entering this subroutine, first, 0 is set to the variable N1 (S
601). Then, the variable N1 is substituted into the variable N2, the value of the sum of the variables N1 and N2 is substituted into the variable N, and then the evaluation function f
(N) is calculated (S603, S605). Further, the value N1 + 1 is substituted into the variable N2, the value N1 + N2 is substituted into the variable N, and then the evaluation function f (N) is calculated (S60).
7, S609). When the calculation of the evaluation function f (N) is completed, the value of N1 + 1 is substituted into the variable N1 (S611).
The above-described processing of S603 to S611 is repeated 25 times until the variable N becomes 25, that is, shifting by 1 bit (S613, S603 to S611).

After obtaining 25 correlation evaluation functions f (N), the minimum value, that is, the region having the highest degree of coincidence is obtained from these (S615). Then, a default check process is performed, and if the default is 0, a distance measurement value with a certain precision or more is obtained, so an interpolation calculation process is executed and the process returns (S615, S617, S619, S621).
If the default is not 0, the interpolation calculation process is not executed and the process returns (S617, S619).

Correlation evaluation function f in S605 and S609
The process (N) will be described with reference to the subroutine shown in FIG. The correlation evaluation function f (N) calculation process is
The sum of the differences between the corresponding bit data in the left and right photometric areas,
This is a process for obtaining the number of bits in the photometric area.

First, 0 is put in the variable i, and the correlation evaluation function f
0 is put in (N) (S631). Then, with respect to the correlation evaluation function f (N), i is incremented by 1 from 0 to W0, and the calculation is returned (S633, S635, S).
637). Correlation evaluation data is obtained by this processing.

The default check process called in S617 will be described with reference to the subroutine shown in FIG. The default check process is a process of determining whether or not the contrast is low, and if the contrast is not low, whether or not a distance object includes a distance object.

Upon entering this processing, first, 0 is set to the default (S651). Then, the maximum value and the minimum value of each bit data of the left and right line sensors are memorized, the respective differences DL and DR are calculated, and when the difference is less than a predetermined value, it is determined to be low contrast and the default value is set to 1 And return (S653, 655, 65
7).

When the differences DR and RL are equal to or larger than the predetermined values, it is checked whether or not the minimum value is one, and if it is one, the proper distance measurement data has been obtained, and therefore the process directly returns (S655, S659). ). When there are two or more local minimum values, there is a possibility that a distant object is included, so the minimum local minimum value K1 and the next minimum local minimum value K
2 is selected and the difference is taken (S659, S661). Then, if the difference is larger than the predetermined value, it is assumed that proper distance measurement data is obtained, and therefore the process directly returns (S663). If the difference is smaller than the predetermined value, the perspective object is included. Since there is a high possibility, the default is set to 2 and the process returns (S663, S665).
By the above processing, 0 is set to the default when an appropriate distance measurement value is obtained, 1 is set to the default when the low contrast is set, and 2 is set to the default when the perspective object is included.

Details of the distance measurement value selection processing of S325, which is a feature of this embodiment, will be described with reference to the subroutine shown in FIG. In this distance measurement value selection processing, the threshold value (reliability determination level) for validating or invalidating the distance measurement value is set in two stages, and the distance measurement value having the reliability of the first stage reliability determination level A or higher is determined. If it is not obtained, the distance measurement value is selected from the distance measurement values that have obtained the reliability of the second stage reliability determination level B or higher, which is lower than the first stage reliability determination level A, The feature is that the largest distance measurement value is extracted from the distance measurement values selected as determined to be reliable in this way. In this embodiment, this reliability judgment level is set based on the magnitude of the slope of the evaluation value data with the minimum value sandwiched in the evaluation value data. As described above, it can be estimated that the larger the slope, the higher the reliability.

When the flow chart shown in FIG. 23 is entered,
First, a distance measurement area for calculating a distance measurement value is set (S70).
1), the distance measurement value (correlation evaluation data and subject distance) is calculated for the set distance measurement area (S703). The distance measurement values are set for all distance measurement areas by sequentially setting the distance measurement areas (S705, S701, S703).

When the distance measurement values have been obtained for all the distance measurement areas, the maximum value max is detected from the distance measurement values of the distance measurement areas whose reliability is higher than the first reliability level A (S70).
7, S709). Here, the maximum value max refers to the value of x-B (see FIG. 5). That is, the larger the maximum value max, the shorter the distance.

In this embodiment, the maximum value max is detected from the distance measurement values in the distance measurement area having an evaluation value higher than the predetermined first reliability level A. If the detected maximum value max is larger than 0, the maximum value max is set as distance data (S721).

If there is no distance measurement value having a reliability higher than the first reliability level A, or if the maximum value max is 0 or less even if it exists, the reliability level L is set to the first level.
Is set to a second reliability level B, which is smaller than the reliability level A, and the maximum value max is detected from the range-finding values at which the reliability of the second reliability level B or higher is obtained (S70).
7, S709, S711, S713, S715). Then, the maximum value max is assigned to the distance data and the process returns (S721). Here, when the evaluation value equal to or higher than the second reliability level B is not obtained, or even when the evaluation value is obtained and the maximum value max is 0 or less, a normal distance measurement value is obtained. Since there is no error bit, error bit set processing is performed (S717, S719).

The above S707 to S711 and S721
By the process of S71, a highly reliable range finding value is obtained, and S71
By the processes of 1, S713, S715, and S717, the distance measurement value can be obtained under wider conditions.

The maximum value detection processing in S709 and S715 will be described with reference to the subroutine shown in FIG. When this subroutine is entered, first, 0 is set to the maximum value max. Then, the following processing is executed for all five distance measuring areas. First, absolute values R1 and R2 of slopes before and after the minimum value of the correlation evaluation data are obtained (see FIG. 9). Then, the smaller one of the absolute values R1 and R2 is set as the reliability value R (S733, S735, S73).
7). Then, the reliability value R is compared with the reliability level L to determine whether or not there is reliability (effectiveness).

When the reliability value R is lower than the reliability level L and the distance measurement value is larger than the maximum value max, the distance measurement value is substituted for the maximum value max (S739, S741, S).
743, S745). When the reliability value R is equal to or higher than the reliability level L, or when the distance measurement value is equal to or lower than the maximum value max even if the reliability value R is lower than the reliability level L, max = 0 is kept (S739, S745 or S739). , S
741, S745). The above-described processing of S733 to S743 is executed for all distance measuring areas and the process returns (S745).

By the maximum value detection processing of S731 to S743, when called in S709, the maximum value max is selected from the distance measurement values of the distance measurement area in which the reliability value R of the reliability level A or higher is obtained. When called in S715, the maximum value max is selected from the distance measurement values in the distance measurement area in which the reliability value R of the reliability level B or higher, which is lower than the reliability level A, is obtained.

As described above, in the present embodiment, the reliability of the five distance measurement values is first selected from among the reliable distance measurement values of the high reliability level A or higher, so that the accurate distance measurement values can be obtained. can get.
When a reliable distance measurement value of the reliability level A or higher is not obtained, the reliability determination level is expanded to select from the reliable distance measurement values of the reliability level B or higher. The frequency with which distance measurement is impossible decreases. Further, in the present embodiment, the reliability judgment is based on the slope of the correlation evaluation data, so that the low-contrast distance measurement value can be eliminated without making the contrast judgment.

As described above, in the present embodiment, the determination of the reliability of the distance measurement value is performed in two steps, but it may be performed in three steps or more. In this embodiment, there are five distance measuring areas, but four
The number may be less than or equal to 6 or may be greater than or equal to 6, and the arrangement thereof is not limited to this embodiment. Although the distance measurement value to be selected is the maximum value max, the distance measurement value corresponding to the closest object may be selected.

[0062]

As is apparent from the above description, the distance measuring apparatus of the present invention sets the level at which the distance measuring data is valid and invalid in a plurality of stages in the multi-range distance measurement, and sets the level higher than the highest first level. If there is no proper distance measurement value among the distance measurement values, then the distance measurement value is expanded to the distance measurement value of the second level or lower, which is lower than the first level, and the proper distance measurement value is selected. While maintaining the reliability of the value, it is possible to prevent the distance measurement from becoming impossible.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a lens shutter camera equipped with a distance measuring device of the present invention.

FIG. 2 is a rear view of the lens shutter camera.

FIG. 3 is a block diagram showing a main part of a circuit configuration of the lens shutter camera.

FIG. 4 is a diagram showing an example of a configuration of an AF distance measuring unit mounted on the lens shutter camera.

FIG. 5 is a diagram illustrating a distance measuring principle of the AF distance measuring unit.

FIG. 6 is a diagram showing a relationship between a distance measuring area of the AF distance measuring unit and a light receiving area (distance measuring area) on a line sensor.

FIG. 7 is a diagram illustrating a mutual relationship between distance measurement areas on the line sensor.

FIG. 8 is a diagram showing a positional relationship of photodiodes used in an evaluation function calculation f (N).

FIG. 9 is a diagram for explaining how to obtain a minimum value and how to obtain reliability from evaluation value data by an interpolation method.

FIG. 10 is a bar graph showing image data of left and right line sensors, image data of a distance measurement area, and evaluation values.

FIG. 11 is a flowchart showing the main processing of this embodiment.

FIG. 12 is a diagram showing a subroutine relating to the shooting process.

FIG. 13 is a diagram showing a subroutine relating to the shooting process.

FIG. 14 is a diagram showing a subroutine relating to the distance measurement processing.

FIG. 15 is a diagram showing a subroutine relating to the distance measurement processing.

FIG. 16 is a diagram showing a subroutine relating to distance measurement area setting processing.

FIG. 17 is a diagram showing a subroutine relating to data correction processing.

FIG. 18 is a diagram illustrating a subroutine relating to left sensor correction processing.

FIG. 19 is a diagram illustrating a subroutine relating to right sensor correction processing.

FIG. 20 is a diagram showing a subroutine relating to distance measurement value calculation processing.

FIG. 21 is a diagram showing a subroutine relating to correlation evaluation function f (N) calculation processing.

FIG. 22 is a diagram showing a subroutine relating to default selection processing.

FIG. 23 is a diagram showing a subroutine relating to distance measurement value selection processing.

FIG. 24 is a diagram showing a subroutine relating to maximum value detection processing.

[Explanation of symbols]

 11 camera body 13 zoom lens 31 CPU (calculation means, reliability determination means) 51 AF distance measurement sensor unit 53L left line sensor 53R right line sensor

Claims (5)

[Claims] 1. A distance measuring device having a distance measuring sensor having a pair of line sensors, each of which has a plurality of light receiving means for photoelectrically converting subject light received by the light receiving device, integrating the light, and outputting image data. Calculation means for calculating a distance measurement value based on a video data group of a plurality of distance measurement areas of the pair of line sensors, and for each of the distance measurement areas, reliability of the video data group of the distance measurement area is determined. Reliability determination means and distance measurement value selection means for selecting one distance measurement value that matches a predetermined condition from the distance measurement values of the distance measurement area determined by the reliability determination means to be reliable. However, the reliability judgment means has a plurality of reliability judgment levels,
The reliability is judged from the highest reliability judgment level among the plurality of reliability judgment levels, and the next highest reliability judgment is made when there is no distance measurement area where a video data group higher than the reliability judgment level can be obtained. A distance measuring device characterized by judging the reliability of a video data group according to a level. 2. The distance measuring device according to claim 1, further comprising a pair of symmetrically arranged image forming lenses, wherein the pair of line sensors are provided at an image forming position of the left and right image forming lenses or before and after the image forming positions. Distance measuring device characterized by being arranged. 3. The object distance calculation method according to claim 2, wherein the calculation means calculates an image interval of the same subject from a pair of image data groups obtained from corresponding distance measurement areas of the left and right line sensors. Distance measuring device having a function of 4. The calculation means according to claim 2, wherein the calculation means obtains correlation data while shifting the pair of video data groups by a predetermined video data unit, and the slope before and after the extreme value of the correlation data is used as a reliability determination level. The distance measuring device having the feature. 5. The reliability determination means according to claim 1, wherein the reliability determination level is successively lowered when there is no distance measurement area where a video data group having a highest reliability determination level or higher is obtained. A distance measuring device characterized by judging the reliability of a data group.