JPH11153750A - Multi-point range-finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-point range finder by which surer and more highly accurate range-finding is executed by selecting data applied for automatic focusing operation from the range-finding data of plural range-finding points. SOLUTION: This device possesses a center part range-finding means 1a executing the range-finding of the center part to a photographic image plane and outputting first range-finding data, a peripheral part range-finding means 1b executing the range- finding of the peripheral part of the photographic image plane and outputting second range-finding data, first and second reliability data outputting means 2a and 2b calculating and outputting the data showing the reliability of the first and second range-finding data, a first discriminating means 3a discriminating the validity/invalidity of the first range-finding data by comparing the output value of the first reliability data outputting means 2a with a first reliability judging level value and a second discriminating means 3b discriminating the validity/invalidity of the second range-finding data by comparing the output value of the second reliability data outputting means 2b with a second reliability judging level value set at a value stricter than the first reliability judging level value and a selecting means 5 selecting and outputting desired data out of the effective data in the first and second range-finding data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multipoint distance measuring device,
In detail, a distance measuring device provided in a photographing device such as a camera, which detects a distance to a subject and performs an automatic focus adjustment operation based on the detection result, has a plurality of distance measuring points in a photographing screen. The present invention relates to a multipoint distance measuring device.

[0002]

2. Description of the Related Art Conventionally, a photographing device such as a camera for taking a photograph or the like (hereinafter simply referred to as a camera) is provided with a distance measuring device for detecting a distance from the camera to a subject. Based on the subject distance data detected by the above, the photographing lens is advanced and retracted in the optical axis direction via a driving mechanism including driving means such as a motor, thereby automatically adjusting the focal position of the photographing lens.
Various proposals have been made for an autofocus camera having a so-called AF mechanism, and the camera has been put to practical use.

[0003] The distance measuring device irradiates a light beam such as an infrared ray to a subject, and receives a reflected light beam after the irradiation light is reflected by the subject, so that the light beam is reflected by the reflected light beam. An active distance measuring device that applies a so-called triangulation method that detects a distance from a camera to a subject by obtaining an angle to be formed, or each image of two images obtained by a pair of optical systems A so-called phase difference detection type (passive type) distance measuring device which detects a phase difference of information and obtains subject distance data for performing a focus adjustment operation based on the phase difference is disclosed in, for example, Japanese Patent No. Various proposals have been made in, for example, Japanese Patent Application Laid-Open No. 2620235 and Japanese Patent Application Laid-Open No. 3-33709, and are generally put to practical use.

Japanese Patent No. 2620235 proposes a distance measuring device which is a signal forming device for forming a signal for adjusting the focus of a camera or the like.
The ranging apparatus disclosed in the publication employs a multipoint ranging method having a plurality of ranging areas (also referred to as ranging points) in a shooting screen, and all of the plurality of ranging points are used. By performing various comparisons, calculations, etc. on the distance measurement results,
It is configured to determine the focal position of the taking lens.

The distance measuring device disclosed in Japanese Patent Laid-Open Publication No. 33709/1991 is a so-called passive type distance measuring device and includes an AF comprising a line sensor such as a CCD.
The sensor is divided into a plurality of blocks, and distance measurement is performed for each block. Then, a block having a contrast equal to or greater than a predetermined value is selected, a correlation operation is performed on the selected block, and an automatic focus adjustment operation is performed based on the output of the block having the minimum correlation value, that is, the block having a large contrast. It is like that.

Here, the principle of a general passive type (phase difference detection type) distance measuring device will be briefly described below. FIG. 7 is a conceptual diagram showing a general passive type distance measuring device. As shown in the figure, the passive distance measuring device is composed of a pair of imaging lenses 101 and 102 and a pair of line sensors 103a and 103b corresponding thereto. Note that this line sensor 103a,
As the 103b, for example, a CMOS type one-dimensional line sensor or the like is used.

The imaging lens 101 and the imaging lens 102
Are spaced apart from each other by the base line length S.
The line sensors 103a and 103b are respectively disposed at positions behind the optical axes 01 and 102 by a focal distance f.

The line sensor 103a is connected to L1
A total of n elements up to Ln are arranged side by side, and the line sensor 103b has a total of n + m elements R1 to R (n + m) arranged side by side.

[0009] In the distance measuring apparatus thus configured,
Each light beam incident on the imaging lenses 101 and 102 from the point A of the subject 100 located at a position L away from the subject (hereinafter simply referred to as a subject distance) is a point on the line sensors 103a and 103b, respectively. Is imaged. In this state, each line sensor 103a, 1
When the output of the image information of each element of 03b is graphed, it can be represented by curves 105a and 105b shown in FIG.

Here, the pair of line sensors 103
One of the line sensors 103a and 103b is referred to as a reference unit, and the other line sensor 103b is referred to as a reference unit. In this case, on the reference portion (103a) side, a light beam from the point A of the subject 100 that has passed through the optical axis center point Ba of the imaging lens 101 forms an image on the imaging point Bb. On the other hand, on the reference section (103b) side, the imaging lens 1
The light flux from the point A transmitted through the optical axis center point C of No. 02 forms an image at the image forming point E. The imaging point E moves in the horizontal direction of the line sensor 103b as the subject distance L changes. In other words, the closer the subject distance L is,
The imaging point E forms an image at a position on the sensor 103b corresponding to the imaging point Bb, that is, at a position away from the reference point D,
As the subject distance L increases, the imaging point E forms an image closer to the reference point D. Then, when the subject is at infinity, the imaging point E forms an image on the reference point D.

That is, the line sensor 103a on the reference portion side
Of the reference unit corresponding to the imaging point Bb
3b between the reference point D of FIG. 3b and the image forming point of the point A of the subject 100 on the reference portion side, that is, the image forming point E of the light flux from the point A transmitted through the optical axis center point C of the image forming lens 102. The amount changes according to the subject distance L. Therefore, at the time of distance measurement, if this deviation amount is calculated, distance data relating to the subject distance L will be obtained.

More specifically, first, a sensor output of image information of an image forming point Bb of the line sensor 103a on the reference portion side;
The correlation calculation is performed with the sensor output of the image information of the line sensor 103b on the reference unit side. Then, by detecting the point (the imaging point E in this case) which is the closest to both, the imaging point B is detected.
b, that is, a shift amount (phase difference) between the reference point D and the imaging point E
Calculate X.

Here, the calculation for calculating the shift amount X will be described in more detail. First, the sum of the absolute value of the difference between the sensor output of the image information of the reference unit and the sensor output of the image information of the reference unit, that is, the correlation value is calculated. This calculation is performed for all the elements corresponding to the reference part and the reference part, and the element having the smallest correlation value calculated as a result is the image forming point. Therefore, the subject distance can be obtained by calculating the amount of deviation between the detected imaging point and the reference point.

More specifically, referring to the example shown in FIG.
First, an operation is performed on the element L1 on the reference section side and the element R1 on the reference section side, and then an operation is performed on the element L2 and the element R2,.
.., Each performs a correlation operation between the same element Ln and the same element Rn. The following equation is used for the correlation operation performed at this time.

[0015]

(Equation 1)

Subsequently, the same correlation operation is performed by shifting the element on the reference portion side by one element. That is, the elements L1,..., Ln on the reference section side and the elements R2,.
This is the (n + 1) correlation operation. After performing a series of correlation operations in which the elements on the reference portion side are shifted by m in this way, the minimum value of all the correlation values is obtained. Since the element having the minimum value is the imaging point, the shift amount is obtained from the number of shifts of this imaging point.

In order to obtain the deviation amount with higher accuracy, the extreme value of the correlation value curve is calculated by performing an interpolation operation from the minimum value of the correlation value obtained as described above and a value in the vicinity thereof. After that, the shift number at that point may be calculated, and this may be converted into a shift amount.

Further, a subject distance is obtained based on the displacement amount calculated in this manner. The conversion of the subject distance L into the distance data is performed based on the base line length S and the imaging lenses 101 and 1.
Assuming that the focal length f and the shift amount X are 02, the following equation is used.

L = (S × f) / X (2) When performing focus adjustment based on the distance data of the subject distance L obtained in this manner, the subject distance L
Is converted into a moving distance from a reference position (for example, a position at infinity) of the photographing lens, and the photographing lens is driven by the moving distance. In the case of a multi-point distance measuring device having a plurality of distance measuring points in a shooting screen, FIG.
It can be configured by providing a plurality of distance measuring devices as shown in FIG. Also, a multi-point distance measuring device can be realized by dividing one line sensor into a plurality of regions and configuring the device shown in FIG. 7 for each region.

[0020]

However, according to the means disclosed in Japanese Patent No. 2620235, since a plurality of distance measuring points are provided in the photographing screen, a desired main subject is not displayed on the photographing screen. Can be focused on the desired subject even if it is out of the approximate center of the camera.However, the distance measurement is performed at a plurality of ranging points, and a complicated comparison is performed based on all the ranging results. Since the calculation is performed, the distance measuring circuit becomes complicated and large-scale, and the time required for various calculations is increased.

According to the means disclosed in JP-A-3-33709, a block to be subjected to focus adjustment is selected based on the correlation value and the magnitude of contrast. In the case where there is a higher-contrast subject in another undesired part (subject) in the photographing screen, the automatic focus adjustment operation may be performed at a position not intended by the photographer.

On the other hand, in the general passive distance measuring apparatus described with reference to FIG. 7, even when the above-described correlation calculation is performed, for example, when the contrast of the subject is low, the correlation value obtained by this calculation is Will not cause a significant change. Therefore, the correlation value (data) obtained in such a case becomes data with very low reliability as to whether or not it is a desired subject, that is, whether or not it is a desired focus position to be focused. Problem.

Even if the calculation of the shift amount is performed on the basis of such low-reliability data, there is a possibility that an erroneous focus adjustment operation may be performed, and thus a focus adjustment operation for an undesired subject may be performed. There is a problem.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a method for photographing a desired subject by using a plurality of distance measurement points provided in a photographing screen when photographing. In a multi-point distance measuring device that detects the distance to the distance and performs the automatic focus adjustment operation based on the detection result, the distance measurement data to be employed in the automatic focus operation is selected from the distance measurement data at a plurality of distance measurement points. An object of the present invention is to provide a multi-point distance measuring apparatus capable of more reliably and accurately measuring a distance to a desired subject by reliably selecting distance data.

[0025]

In order to achieve the above object, a multipoint distance measuring apparatus according to a first aspect of the present invention measures a center portion of a photographing screen and outputs first distance measurement data. Distance measuring means, peripheral distance measuring means for measuring the peripheral area of the photographing screen and outputting second distance measuring data, and calculating and outputting data representing the reliability of the first distance measuring data. First reliability data output means, second reliability data output means for calculating and representing data representing the reliability of the second distance measurement data, and output of the first reliability data output means Value and first
A first determination unit that determines whether the first distance measurement data is valid or invalid, and an output value of the second reliability data output unit. Is compared with a second reliability determination level value set to a value stricter than the first reliability determination level value to determine whether the second distance measurement data is valid or invalid. It is characterized by comprising a second determination means and a selection means for selecting and outputting desired data from the valid ones of the first and second distance measurement data.

According to a second aspect of the present invention, in the multipoint distance measuring apparatus according to the first aspect, the first and second determining means include an output value of the first and second reliability data output means. And the first and second reliability determination level values are compared with each other. When the first and second reliability determination level values are larger, the distance measurement data is validated, and the second reliability is determined. The first reliability determination level value is larger than the determination level value.

According to a third aspect of the present invention, in the multipoint distance measuring apparatus according to the first aspect, the first and second judging means include an output value of the first and second reliability data outputting means. And the first and second reliability determination level values are compared with each other. When the first and second reliability determination level values are smaller, the distance measurement data is validated, and the second reliability is determined. The first reliability determination level value is smaller than the determination level value.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a block diagram showing a schematic configuration of a camera employing a multipoint distance measuring apparatus according to a first embodiment of the present invention. In the present embodiment, a multi-point distance measuring apparatus having three distance measuring areas (ranging points) is exemplified.

As shown in FIG. 1, components such as various circuits constituting the camera are electrically connected to a CPU 11 composed of a microcomputer or the like, and the entire camera is controlled by the CPU 11. .

The camera has a reset circuit 13 for generating a reset pulse (signal) for initializing the CPU 11, and an EEPROM comprising a nonvolatile memory and the like.
OM 15, a DX terminal 16 to which DX code information of a film cartridge (not shown) loaded in the camera body is input, and a multipoint AF circuit (AFIC) 17 having a plurality of phase difference AF sensors. , An auxiliary light lamp 18 for generating auxiliary light for distance measurement, an operation switch group (SW) 20 including various operation switches such as a release switch and a mode switch, and a plurality of light emitting diodes (L).
ED), etc., which are provided on the exterior of the camera (not shown) or the like to display various information such as strobe emission notice and focus indication in the viewfinder, etc. A liquid crystal display (LC) which is an external display panel that displays the number of frames and the camera shooting mode
D) 22 and a photometric unit 24 for detecting subject brightness and the like
, Shutter motor (Ms) 25 and hoist motor (Mw)
A motor driver IC 28 for controlling various motors such as a zoom motor (Mz) 27;
Transmission and reception of signals with C28 and photometric unit 24, LCD 22
(IFIC) 23 for supplying power to the camera and checking the battery and charging the strobe 35 as a flash light emitting device, a photo interrupter (PI) 30 for detecting the lens position of a photographic lens (not shown), and a film feeder. Photo interrupter (PI) 3 for detecting the amount of delivery
2, a zoom encoder 33 for detecting a zoom position,
It is composed of various members such as a date module 34 for optically recording photographing data such as date and time on a film.

The multi-point AF circuit 17 includes a central AF unit for detecting first distance measurement data representing a central object distance.
A sensor 17a, and a right peripheral AF sensor 17b and a left peripheral AF sensor 17c for detecting second distance measurement data representing subject distances of peripheral parts near the right and left sides of the central AF sensor 17a in the photographing screen. Three AF sensors are provided.

Here, a multipoint distance measuring device comprising the multipoint AF circuit 17 and the like will be described below. FIG. 2 is a block diagram showing a main configuration of the multipoint distance measuring apparatus according to the present embodiment. This multi-point distance measuring device uses the central AF sensor 1
7a, a center distance measuring unit 1a corresponding to the right and left peripheral AF sensors 17b, 17c, and a distance measuring unit obtained by each of these distance measuring units 1a, 1b. A calculating means 4 for converting the results (first and second distance measurement data) and the like into subject distance data; and selecting and outputting distance data representing the closest distance among the distance data calculated by the calculating means 4. Selecting means 5 for calculating and outputting data representing the reliability of the first distance measurement data;
The reliability data output means 2a, the second reliability data output means 2b for calculating and outputting data representing the reliability of the second distance measurement data, and the distance measurement data by the central distance measurement means 1a, that is, The reliability of the output value of the first reliability data output means 2a is determined by the reference value [TH1] of the first reliability determination level.
And the distance measurement data by the peripheral distance measurement means 1b, that is, the second reliability data output means 2b.
Is determined by using the reference value [TH2] of the second reliability determination level, and the second determination means 3b and the like for outputting the determination result to the arithmetic means 4 are provided.

Here, a large flow of the first and second distance measurement data obtained by the central distance measuring means 1a and the peripheral distance measuring means 1b is shown by a chain line in FIG. First, each distance measurement data is output to the calculation means 4 and converted into subject distance data. Thereafter, the subject distance data is output to the selecting means 5, and the selecting means 5 selects desired data, that is, selects and outputs distance data representing the closest distance.

The flow of the first and second distance measurement data will be described in more detail. First, the sensor outputs obtained by the center and peripheral distance measurement means 1a and 1b are the first and second distance measurement data.
The data is output to the second reliability data output means 2a, 2b.
The sensor output is converted here into first and second distance measurement data for representing reliability. That is, the first and second
Are subjected to a correlation operation in the reliability data output means 2a and 2b, and output to the first and second determination means 3a and 3b. The output values (the first and second distance measurement data) are compared with reference values of the first and second reliability determination levels which are set in advance here, whereby the first and second distance determination data are obtained. Of the distance measurement data is determined. Then, based on the result of the determination, only the distance measurement data determined to be reliable is converted into subject distance data by the calculating means 4,
After that, the above-mentioned selection by the selection means 5 is made and output.

Returning to FIG. 1, the EEPROM 15
Number of frames shot on the film ・ Camera operation status data (during hoisting operation, rewinding operation, etc.) ・ Abnormal data (failure location) ・
Various data such as adjustment data (predetermined data that differs for each camera, such as shutter control correction data, autofocus correction data, and battery check data) are stored in advance. For this reason, even when the battery is removed from the camera body at the time of battery replacement, for example, these various data are not lost, and the data is valid even after the battery is replaced. Furthermore, the above EEPR
In the OM 15, reference values ([TH1], [TH2]) of the first and second reliability determination levels used in the first and second determination units 3a and 3b are stored in advance.

The EEPROM 15, the EXT terminal 19,
The multipoint AF circuit 17 is electrically connected by the same serial line in order to effectively use the input / output port of the CPU 11, and transmits and receives data to and from the CPU 11 by serial communication.

The interface 23 is connected to the CPU 11
A decoding function for selecting Ms25, Mw26, and Mz27 in accordance with a command from the CPU, and this decoding function also includes switching of a photometry method such as average photometry and spot photometry in the photometry unit 24.

The operation of the above-configured camera will be briefly described below. As described above, this camera is entirely controlled by the CPU 11, and
The CPU 11 starts its operation after being initialized by receiving a reset pulse (signal) from the reset circuit 13. The reset pulse of the reset circuit 13 is
Occurs when a power battery (not shown) is loaded into the camera body or when the power switch is switched from the off state to the on state.

When the EEPROM 15 is set to the reading mode, first, DX code information of a film cartridge (not shown) is input from a DX terminal 16 and is input to the CPU 11 via a serial line. Next, the EEPROM
The 15 data items are transferred to the CPU 11.

The multipoint AF circuit 17 comprises a plurality of phase difference type AF sensors as described above, and includes a predetermined area near the center of the photographing screen (hereinafter simply referred to as the center). A predetermined area adjacent to the center (hereinafter, referred to as a central area)
The respective distances to the subject in the peripheral area are simply detected by the non-TTL method, and the subject distance data as the detection result is supplied to the CPU 11.

When the photometric value of the photometric unit 24 is equal to or less than a predetermined value (low brightness), the CPU 11
In order to generate auxiliary light for distance measurement by the circuit 17, the auxiliary light lamp 18 is turned on in accordance with the operation of the multipoint AF circuit 17.

The various motors 25, 26, 27
Are driven via the motor driver 28 by the decode signal of the interface 23. Here, the shutter motor (Ms) 25 drives the lens for automatic focusing during normal rotation, and drives the shutter during reverse rotation. In the camera of the present embodiment, it is assumed that a general lens shutter is employed as a shutter used for a small camera.

Next, when performing the automatic focusing operation,
By rotating the motor 25 in the normal direction, the CPU 11 outputs three distance data detected by the multi-point AF circuit 17 and E
The drive of the photographing lens (not shown) is controlled until the target position obtained by the calculation with the adjustment data of the EPROM 15 is reached.

Here, the reset position of the photographing lens is confirmed by the ON state of the switch 29, and the lens position is confirmed by the number of pulses of the photo interrupter 30 generated per unit movement amount of the photographing lens.

That is, the CPU 11 refers to the output of the photo interrupter 30 to control the forward rotation, brake and off of the motor (Ms) 25 to stop the taking lens at the target position.

The reset position of the motor (Ms) 25 during the shutter control is confirmed by turning on the switch 31.
By changing the duty driving ratio in accordance with the adjustment data in the EPROM 15, control is performed so that a constant aperture waveform is maintained.

The hoist motor (Mw) 26 winds up the film at the time of forward rotation, and rewinds the film at the time of reverse rotation. The winding control for one frame of the film is performed by counting the number of pulses of the photo interrupter 32.

The photointerrupters 30 and 32 are provided with a shutter motor (Ms) 25 and a hoisting motor 26, respectively.
It is turned on only when (Mw) is selected, and the outputs of the photointerrupters 30 and 32 are input to the CPU 11 after digitally removing noise through the IFIC 23. This is because if the outputs of the photointerrupters 30 and 32 are directly input to the CPU 11, an error may occur in the count value due to noise or the like.

The zoom motor (Mz) 27 zooms the photographing lens, and the zoom position can be detected by the zoom encoder 33. The above EE
During the operation of writing data to the PROM 15, generation of the reset pulse of the reset circuit 13 is prohibited.

Next, the distance measuring operation performed in the camera having the multipoint distance measuring apparatus of the present embodiment will be described with reference to the flowchart of FIG. FIG. 3 is a flowchart showing a subroutine of the distance measuring operation. When this subroutine of the distance measuring operation is executed, prior to this,
First, in a main routine of the camera, a release button (not shown) for starting a photographing operation is operated, and a release switch of an operation switch group (SW) 20 linked to this is turned on. Upon receiving the ON signal from the release switch, the CPU 11
The execution of the distance measuring operation shown in FIG. 3 is started.

In step S1, first, the first and second determination means 3a and 3b determine, from among various data stored in the EEPROM 15, data for determining the reliability of the distance measurement data, ie, the central data. Reference value [TH1] of the first reliability determination level for determining the distance measurement data of the section
And a reference value [TH2] of a second reliability determination level for determining the distance measurement data of the left and right peripheral portions. Here, the reference values of the first and second reliability determination levels are:
The relationship is set as in the following equation. TH1> TH2 (3) In other words, the reference value [TH2] of the second reliability determination level for determining the distance measurement data of the left and right peripheral portions is the first for determining the distance measurement data of the center portion. The reference value of the reliability determination level [T
H1]. These reference values [T
H1] and [TH2] are compared with the output value of the correlation operation performed in the first and second reliability data output units 2a and 2b, that is, the minimum value of the correlation value, as described later. Therefore, setting a lower criterion value here means setting a stricter criterion. In other words, the above expression (3) means that the reliability of the distance measurement data of the peripheral portion is determined by a stricter criterion than the distance measurement data of the center portion.

Thus, when the data at the central portion and the data at the peripheral portion (the minimum value of the correlation value) are close to each other, the data at the central portion at which the reliability is determined by a criterion that is less strict than the data at the peripheral portion is determined. Is considered to be more reliable,
In the data selection step S17 (details will be described later), the data in the central part is selected with priority.

It should be noted that the reliability of the data in the peripheral portion is determined based on a stricter reference value than the data in the central portion, so that the distance measurement data in the central portion has priority over the distance measurement data in the peripheral portion. The selection is made in consideration of the fact that the probability that the desired main subject to be photographed is located near the substantially central portion in the photographing screen is high when performing normal photographing. This is the setting made.

Next, in steps S2 to S6, a distance measuring operation is performed at the center distance measuring point by the central AF sensor 17a as the central distance measuring means 1a. In step S2, the central AF sensor 17a of the multi-point AF circuit 17 acquires image data of the subject image at a substantially central portion of the shooting screen (integration operation). Thereafter, in step S3, based on the pixel data obtained in step S2, the first reliability data output means 2a
In the above, the correlation calculation according to the above equation (1) is performed, and first distance measurement data (correlation value) as data representing reliability is calculated. Then, the minimum value SCmin of the correlation values is output to the first determination unit 3a.

Subsequently, in step S4, the first determination means 3a determines the minimum value SCmin of the correlation value calculated in step S3 and the reference value [1] of the first reliability determination level read in step S1. TH1]. Here, if SCmin ≦ TH1, the process proceeds to step S5, and if SCmin> TH1, the process proceeds to step S7.

In the above step S4, SCmin
If it is determined that ≤ TH1, the first distance measurement data that is the distance measurement result at the center obtained in step S3 is:
Since it is determined that the data is reliable (highly reliable), the data is output to the arithmetic unit 4 and the process proceeds to the next step S5.

In step S5, the calculating means 4 calculates the amount of displacement. Here, an interpolation operation is performed using the minimum value SCmin of the correlation value and a correlation value in the vicinity thereof to calculate the extreme value of the correlation value curve, and the shift number at that point is calculated and obtained. Is converted to Then, in step S6, the shift amount X is converted into subject distance data, and the distance data is output to the selection means 5.

Next, in steps S7 to S11, the left peripheral AF sensor 17c, which is the peripheral distance measuring means 1b, performs a distance measuring operation at the left peripheral distance measuring point.
This distance measurement operation is substantially the same as the above-described distance measurement operation at the central portion, and therefore will be briefly described here.

First, in step S7, the multipoint AF
After the left peripheral AF sensor 17c of the circuit 17 performs the integration operation on the substantially left peripheral portion of the photographing screen, in step S8, the second reliability data output unit 2b outputs
The correlation calculation of the above equation (1) is performed to calculate second distance measurement data (correlation value) which is data for representing reliability. Then, the minimum value SLmin of the correlation values is output to the second determination means 3b.

Subsequently, in step S9, the second determination means 3b compares the minimum value SLmin of the correlation value with the reference value [TH2] of the second reliability determination level read in step S1. If SLmin ≦ TH2, the process proceeds to step S10, where SLmin
If> TH2, the process proceeds to step S17.

In the above step S9, SLmin ≦ TH
If it is determined to be 1, it is determined that the second distance measurement data is reliable (highly reliable) data, and the data is output to the arithmetic unit 4 to be processed in the next step S10. Proceed to.

In this step S10, the calculating means 4 calculates the displacement amount X. And
In step S6, the shift amount X is converted into subject distance data, and this distance data is output to the selection means 5.

Subsequently, in steps S12 to S16, the right peripheral AF sensor 17b, which is the peripheral distance measuring means 1b, performs a distance measurement operation of the right peripheral AF point. This distance measuring operation is also substantially the same as the above-described distance measuring operation of the central portion or the left peripheral portion, and the determination made in step S14 (corresponding to step S9) is made in place of the minimum correlation value SLmin. The minimum value SRmin and [TH
2]. Other operations are
The operation is the same as that in steps S7 to S11.

In FIG. 3, after the distance measuring operation for the central portion, the distance measuring operation for the left peripheral portion is performed, and then the distance measuring operation for the right peripheral portion is performed. The order of the distance measuring operation for each of the distance measuring points is not limited to this example. For example, the distance measuring operation is performed in a different order from the example of FIG. You may do it.

As described above, the plurality of distance data obtained by the respective distance measuring means 1a and 1b and output to the selecting means 5 through the respective arithmetic processing are all data for which reliability is ensured. In step S17, the selection means 5 selects the shortest distance (closest distance) from the distance data.
Is selected and output as data for automatic focus adjustment, after which a series of processing is terminated (return).

The selecting means 5 in step S17
Is used to select the subject distance data indicating the shortest distance as the data selection criterion according to the above. Among the data whose reliability has been ensured as described above, the subject located at the closest distance is the subject to be photographed. This is because it is estimated that the probability of being the desired main subject is high.

As described above, according to the present embodiment,
The minimum value of the correlation value obtained by the calculation or the correlation value obtained by the interpolation calculation is compared with a predetermined reference value ([TH1], [TH2]), and the correlation based on the distance measurement result is obtained. If the value is determined to be larger, it is determined that the data has low reliability, the automatic focusing operation based on the data is not performed, and the reliability of the correlation value based on the distance measurement result is reduced. Only when it is determined to be high, the automatic focus adjustment operation is performed based on the data, so that a malfunction related to the automatic focus operation is prevented, and thus a photograph that is surely focused on a desired subject is taken. Can be done easily.

Further, the criterion value for judging the reliability of the distance measurement data at the central portion and the distance measurement data at the peripheral portion are set to different values. Since the distance measurement data in the central part where the main subject is located at a high probability is selected with priority,
The main subject can be surely focused.

Further, the distance measuring operation of the multipoint distance measuring apparatus is not limited to this, and for example, a form shown in a flowchart of FIG. 4 can be considered. That is, FIG. 4 shows the second embodiment of the present invention.
It is a flowchart which shows the ranging operation in the multipoint ranging apparatus of embodiment. Note that the configuration of the multipoint distance measuring apparatus of this embodiment is basically the same as that of the above-described first embodiment, so that the illustration of the configuration is omitted, and those shown in FIGS. I do.

In the sequence (first embodiment) described with reference to FIG. 3 described above, the distance measuring operation is executed for each of the three distance measuring points at the central portion and the left and right peripheral portions, and the reliability of the data is ensured. After the conversion into the subject distance data for all, the distance data is compared to select the data. However, in the sequence of the distance measuring operation of the present embodiment, as shown in FIG. The difference is that after selecting data to be adopted for adjustment, only the selected data is converted into subject distance data.

That is, in the distance measuring operation in this embodiment, as described later, first, the correlation calculation of the sensor output of each distance measuring point by the first and second reliability data output means 2a and 2b and the calculation means After the calculation of the shift amount by the step S4, the judgment means 3a and 3b determine the minimum value S (C, L,
R) min is compared with the determination reference values [Th1] and [TH2], and the determination result is output to the selection means 5, where the distance data representing the closest distance is selected. After that, only the selected distance data is output to the calculating means 4, where it is converted into subject distance data. Therefore, the data flow is slightly different from that of the first embodiment.

Hereinafter, the sequence of the distance measuring operation according to the present embodiment will be described with reference to FIG. First, in step S21, reference values [TH1] and [TH2] of the first and second reliability determination levels for determining the distance measurement data are read, and in the next step S22, each AF sensor 17 is read.
a, 17b, and 17c are performed to perform the data integration operation.

Next, a distance measuring operation is performed at each distance measuring point on the photographing screen. First, in steps S23 to S26, a distance measurement operation is performed at the center, and step S2 is performed.
In 3, the central distance measuring means 1a (AF sensor 17a)
Performs a correlation operation on the sensor output obtained by
Subsequently, in step S24, the displacement X is calculated.

Next, in step S25, a comparison is made between the minimum value SCmin of the correlation value and the determination reference value [TH1]. If it is determined that SCmin ≦ TH1, the process proceeds to step S27. Also, SCmin
If it is determined that> TH1, the distance measurement data at the center is determined to have low reliability, and step S26 is determined.
, The distance measurement data at the center is excluded.

Next, in steps S27 to S30,
After the distance measurement operation is performed in the left peripheral portion, step S
In steps S31 to S34, a distance measurement operation in the right peripheral portion is performed. Since the distance measuring operation in the left and right peripheral portions performed here is substantially the same as the distance measuring operation in the central portion in steps S23 to S26, the description of the sequence is omitted.

As a result of performing the distance measuring operation at each distance measuring point, only highly reliable data is output to the selecting means 5. Then, in step S35, the selection means 5 selects the distance measurement data necessary for performing the automatic focus adjustment. Here, step S2
The deviation amount X calculated in 4, S28, and S32 is compared, and the distance measurement data that is the closest distance is selected. This is because the shift amount and the subject distance correspond to one to one, so that if the shift amount is known, it is possible to determine a ranging point having data that is the closest distance.

Thereafter, in step S36, the selected distance measurement data is converted into subject distance data, and after outputting the same distance data, a series of processing is terminated (return).

As described above, according to the present embodiment,
The same effect as that of the first embodiment can be obtained, and the calculation for converting the distance measurement result (distance measurement data) at each distance measurement point into the subject distance data is omitted, and is adopted for automatic focus adjustment. Since the calculation for converting the power data into the distance data is performed, a higher-speed ranging operation sequence can be realized. Note that the order of the distance measuring operation for each of the distance measuring points such as the central portion and the left and right peripheral portions is not limited to the example of FIG.

In the first and second embodiments described above, two kinds of reference values for the central portion and the peripheral portion are used as the reference values used in the first and second determining means 3a and 3b. Although the determination is made using the data value, in addition to this, it is also conceivable to prepare a plurality of determination reference values that differ depending on the environment at the time of shooting and the state of the camera. For example, shooting environment (subject brightness, direct light / backlight,
Depending on the difference in the camera mode, etc., and the difference in the focal length when a variable-magnification shooting lens is attached, etc. If the photographing environment and the state of the camera are detected and the determination reference value is switched according to the state, a more accurate distance measurement result can be obtained.

FIG. 5 and FIG. 6 show a third embodiment of the present invention. FIG.
FIG. 6 is a conceptual diagram showing a data structure of the EPROM and a flow of the data, and FIG. 6 is a flowchart showing a subroutine when a determination reference value is selected in the distance measuring apparatus of the present embodiment. The basic configuration of the distance measuring apparatus of the present embodiment and the camera using the distance measuring apparatus is the same as that of the first embodiment.
(See FIGS. 1 and 2).

In the distance measuring apparatus according to the present embodiment, the state of the camera is used as a criterion value for determining the reliability of the distance measurement data, for example, as shown in FIG. Etc., a plurality of data corresponding to
It is stored in the EPROM 15.

The plurality of criterion values ([D shown in FIG. 5)
[Data1], [Data2], ..., [Data16]
)) According to the state of the camera during the shooting operation, etc.
The selected reference value is selected in accordance with the sequence shown in FIG.
a, 3b (see FIG. 2) are stored in the RAM 37 as reference values [TH
1] and [TH2]. Then, the reference values [TH1] and [TH2] are determined by the first and second determination means 3.
Referenced in the step of data determination in a and 3b.

The distance measuring operation in the distance measuring apparatus of this embodiment is basically performed in the first and second embodiments (FIGS. 3 and 4).
However, in the present embodiment, the steps before reading the reliability determination data ([TH1], [TH2]) in step S1 shown in FIG. 3 or step S21 in FIG. That is, immediately after the subroutine of the distance measurement operation is started, the subroutine of the selection sequence of the determination reference values ([TH1], [TH2]) shown in FIG. 6 is executed.

As shown in FIG. 6, in step S41, it is determined whether the subject luminance is lower or higher than a predetermined luminance by referring to the photometry result by the photometry unit 24 (see FIG. 1). Perform Here, if it is determined that the luminance is high, the process proceeds to step S42, and in this step S42, it is determined whether the main subject is in the normal light state or the backlight state by referring to the photometry result in the same manner. You. If it is determined that the light is in the normal light state, the process proceeds to step S43. In this step S43, whether the focal length of the photographing lens is set to the wide angle (Wide) side or the telephoto (Tele) side. Is determined. Here, if it is determined that the object is on the telephoto side, step S
In this step S44, among the determination reference values stored in the EEPROM 15, [Da
ta1] and [Data2] are read out and the register 3
6 [Reg. [Data1] in [Reg.
After [Data2] is stored in [2], the process proceeds to the next step S45.

If it is determined in step S43 that the object is on the wide angle side, the process proceeds to step S46.
In this step S46, the criterion values [Data3] and [Data4] are read from the EEPROM 15, and [Reg. [Data]
3] is [Reg. After [Data4] is stored in [2], the process proceeds to the next step S45.

On the other hand, if it is determined in step S42 that the subject is backlit, the process proceeds to step S47. In step S47, whether the focal length of the photographing lens is set to the wide angle side or the telephoto side is determined. A decision is made. Here, if it is determined that the object is on the telephoto side, step S
In step S48, the criterion values [Data5] and [Data6] are read from the EEPROM 15 and [Re] of the register 36 is read.
g. [Data5] in [Reg. 2] to [Da
ta6] is stored, and then the next step S45
Proceed to processing.

If it is determined in step S47 that the object is on the wide-angle side, the process proceeds to step S49.
In this step S49, the criterion values [Data7] and [Data8] are read from the EEPROM 15, and [Reg. [Data]
7] is [Reg. After [Data8] is stored in [2], the process proceeds to the next step S45.

On the other hand, if it is determined in step S41 that the brightness is low, the process proceeds to step S50, and in this step S50, it is determined whether the main subject is in the normal light state or the backlight state. . If it is determined that the light is in the normal light state, the process proceeds to step S51, and in this step S51, it is determined whether the focal length of the taking lens is set to the wide angle side or the telephoto side. If it is determined that the object is on the telephoto side, the process proceeds to step S52. In this step S52, the criterion values [Data9] and [Data10] are read from the EEPROM 15, and [Re] of the register 36 is read.
g. [Data 9] in [Reg. 1]. 2] to [Da
ta10] is stored, and then the next step S4
Proceed to step 5.

If it is determined in step S51 that the object is on the wide angle side, the process proceeds to step S53. In this step S53, the criterion values [Data11] and [Data12] are read from the EEPROM 15. [Reg. [Data1]
1] is [Reg. After [Data12] is stored in [2], the process proceeds to the next step S45.

On the other hand, if it is determined in step S50 that the subject is backlit, the flow advances to step S54 to determine whether the focal length of the photographing lens is set to the wide-angle side or the telephoto side in step S54. A decision is made. Here, if it is determined that the object is on the telephoto side, step S
In step S55, the reference values [Data13] and [Data14] are read from the EEPROM 15 and [Re] of the register 36 is read.
g. [Data 13] in [Reg. 2] to [D
atat14] is stored in the next step S
Proceed to step 45.

If it is determined in step S54 that the object is on the wide angle side, the process proceeds to step S56. In this step S56, the criterion values [Data15] and [Data16] are read from the EEPROM 15, and [Reg. [Data1]
5] is [Reg. After [Data16] is stored in [2], the process proceeds to the next step S45.

Finally, in step S45, [Reg. 1], [Reg. 2] is stored in the RAM 3 of the first and second determination means 3a and 3b.
7 is stored. Then, a series of sequences ends,
It returns to the distance measuring operation sequence (return).

Here, [Reg.
1] is used as the reference value [TH1] of the first reliability determination level for determining the distance measurement data at the center, and [Reg. 2] is written as the reference value [TH2] of the second reliability determination level for determining the distance measurement data of the left and right peripheral portions.

With this configuration, it is possible to perform a distance measurement operation based on the optimum determination reference value in accordance with the state of the camera and the photographing environment. Accurate measurement can be performed, and a higher distance measurement result can be easily obtained.

In this embodiment, as described above, the selection of the determination reference value ([TH1], [TH2]) is performed based on the photometry result by the photometry unit 24, but is not limited to this. For example, AF sensors 17a, 17
b, 17c (see FIG. 1). In this case, the execution of the sequence for selecting the determination reference value ([TH1], [TH2]) is performed after the processing of steps S2, S7, S12 of FIG. 3 or after the processing of step S22 of FIG. Just do it.

In this embodiment, the detection of whether the environment of the subject is in direct light or in backlight is performed based on the result of photometry by the photometry unit 24 and the result of integration by the AF sensor. However, the present invention is not limited to this. For example, the determination may be made by detecting the mode SW of the camera.

Further, the first and second judging means 3a,
The criterion value used for 3b is not limited to the example described above.
For example, it is conceivable to prepare reference values corresponding to various camera modes such as a night view mode.

The determination of reliability described in each embodiment of the present invention is an example, and it is needless to say that the present invention is not limited to these examples. For example, means for normalizing the minimum value SCmin of the correlation value in each of the above embodiments with the contrast information of the subject may be used.

[Supplementary Note] According to the above-described embodiment of the present invention, an invention having the following configuration can be obtained. That is, (1) a center distance measuring unit that measures the distance at the center of the photographing screen and outputs first distance measurement data, and measures the distance around the periphery of the photographing screen and outputs second distance measurement data. Peripheral distance measurement means, first reliability data output means for calculating data representing the reliability of the first distance measurement data, and second reliability data output means for calculating data representing the reliability of the second distance measurement data; 2 reliability data output means, first determination means for determining whether or not the first reliability data is equal to or higher than a first reliability determination level, and wherein the second reliability data is A second determining means for determining whether or not the reliability is higher than a second reliability determining level higher than the first reliability determining level; and determining that the reliability is high by the first or second determining means. Calculating means for calculating subject distance data only for the measured distance data; Multi-point distance measuring device including a selecting means for selecting the object distance data representing the closest distance among the calculation results of the calculation means.

(2) Measure the distance in the center of the photographing screen,
Center distance measuring means for outputting the distance measuring data, peripheral distance measuring means for measuring the peripheral part of the photographing screen and outputting second distance measuring data, and reliability of the first distance measuring data First reliability data output means for calculating data representing
Second reliability data output means for calculating data representing the reliability of the distance measurement data, and a first reliability data determining means for determining whether or not the first reliability data is equal to or higher than a first reliability determination level.
Determination means, and second determination means for determining whether or not the second reliability data is equal to or higher than a second reliability determination level higher than the first reliability determination level, Selecting means for selecting distance measuring data representing the closest distance from the distance measuring data judged to be highly reliable by the first or second judging means; and subject only for the distance measuring data selected by the selecting means A multi-point distance measuring device comprising: calculating means for calculating distance data.

(3) Measure the distance at the center of the photographing screen to
Center distance measuring means for outputting distance measurement data, peripheral distance measuring means for distance measuring peripheral parts of a photographing screen and outputting second distance measurement data, and reliability of the first distance measurement data First reliability data output means for calculating and representing data representing
A second reliability data output unit that calculates and outputs data representing the reliability of the second distance measurement data, a first determination unit that determines the reliability of the first distance measurement data, Second determination means for determining the reliability of the second distance measurement data, arithmetic means for converting the first distance measurement data and the second distance measurement data into subject distance data and outputting the data, And a selection means for selecting and outputting data.

(4) In the multipoint distance measuring apparatus according to supplementary note 3, the first determining means determines whether or not the output of the first reliability data output means is equal to or higher than a first reliability determination level. The second determination means determines whether the output of the second reliability data output means is equal to or higher than a second reliability determination level set to a level stricter than the first reliability determination level. It is determined whether or not there is.

(5) In the multipoint distance measuring apparatus described in Appendix 4, the calculating means converts the distance measurement data into subject distance data based on the determination result by the first and second determination means and outputs the data. The selection means selects subject distance data representing the closest distance from the output of the calculation means.

(6) In the multipoint distance measuring apparatus according to supplementary note 4, the selection means selects distance measurement data representing the closest distance based on a result of determination by the first and second determination means, The calculation means converts only the distance measurement data selected by the selection means into subject distance data and outputs the data.

(7) In the multipoint distance measuring apparatus according to appendix 3, the first determination means is such that an output value of the first reliability data output means is equal to or less than a first reliability determination level value. The second reliability means determines whether the output value of the second reliability data output means is lower than the first reliability determination level value. The calculating means determines whether or not the distance is equal to or less than a determination level value, and converts only the distance measurement data determined to be highly reliable by the first determining means and the second determining means into subject distance data. And the selecting means outputs the first and second signals.
And selects and outputs subject distance data representing the closest distance from the outputs of the determination means.

(8) In the multipoint distance measuring apparatus according to appendix 3, the first judging means is such that an output value of the first reliability data output means is equal to or less than a first reliability judging level value. The second reliability means determines whether the output value of the second reliability data output means is lower than the first reliability determination level value. A determination is made as to whether or not the distance is equal to or less than a determination level value. The selection means indicates a closest distance among the distance measurement data determined to be highly reliable by the first determination means and the second determination means. The distance measurement data is selected and output, and the arithmetic unit converts only the distance measurement data selected by the selection unit into subject distance data and outputs the data.

(9) In the multipoint distance measuring apparatus according to the appendix 3, the predetermined reference values of the first and second reliability determination levels used in the first and second determination means may be nonvolatile in advance. It is stored in memory.

(10) In the multipoint distance measuring apparatus according to the appendix 3, the reference values of the first and second reliability judgment levels used in the first and second judgment means are set at the time of photographing at the time of photographing. Different values are applied depending on the environment and the state of the camera.

(11) In the multipoint distance measuring apparatus according to supplementary note 10, the reference values of the first and second reliability judgment levels are switched by detecting subject brightness.

(12) In the multipoint distance measuring apparatus described in Appendix 10, the reference values of the first and second reliability judgment levels are determined by detecting whether the main subject is in direct light or in backlight. Switch.

(13) In the multipoint distance measuring apparatus according to supplementary note 10, the reference values of the first and second reliability determination levels are switched by detecting a camera mode.

(14) In the multipoint distance measuring apparatus described in appendix 10, the reference value of the first and second reliability determination levels is based on whether the photographing lens is on the wide-angle side or on the telephoto side. Detects and switches.

(15) Distance measuring means for measuring the distance in the center of the photographing screen and outputting the first distance measurement data, and measuring the distance in the periphery of the photographing screen and outputting the second distance measuring data Peripheral distance measuring means, first reliability data output means for calculating and outputting data representing the reliability of the first distance data, and data representing the reliability of the second distance data. And a first determination for determining whether an output value of the first reliability data output means is equal to or less than a first reliability determination level value. Means, and a second reliability data output means, wherein an output value of the second reliability data output means is set to a value lower than the first reliability determination level value.
To determine whether or not the value is equal to or less than the reliability determination level value of
Determination means, an arithmetic means for converting the first and second distance measurement data into subject distance data and outputting the data, and desired data among the first and second distance measurement data or the subject distance data And a selection unit for selecting and outputting a multi-point distance measuring device.

(16) In the multipoint distance measuring apparatus according to appendix 15, the calculating means can be reliably used by the first determining means and the second determining means in the first or second ranging data. Only the distance measurement data determined to be highly probable is converted into subject distance data and output, and the subject distance data representing the closest distance among the outputs is selected and output by the selection means.

(17) In the multipoint distance measuring apparatus according to supplementary note 15, the selecting means may select one of the distance measurement data determined to be highly reliable by the first determining means and the second determining means. The distance measuring data indicating the closest distance is selected and output, and the arithmetic unit converts only the distance measuring data selected by the selecting unit into subject distance data and outputs the data.

[0116]

As described above, according to the present invention, when taking a picture, the distance to a desired subject is detected by a plurality of distance measurement points provided in the shooting screen, and based on this detection result. In a multi-point distance measuring apparatus configured to perform an automatic focus adjustment operation, a desired distance measurement data to be adopted in the automatic focus operation is reliably selected from among the distance measurement data at a plurality of distance measurement points to obtain a desired distance measurement data. It is possible to provide a multi-point distance measuring device capable of more reliably and accurately measuring the distance to a subject.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a camera employing a multipoint distance measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a main configuration of the multipoint distance measuring apparatus of FIG. 1;

FIG. 3 is a flowchart showing a distance measuring operation performed in a camera having the multipoint distance measuring apparatus of FIG. 1;

FIG. 4 is a flowchart illustrating a distance measuring operation in the multipoint distance measuring apparatus according to the second embodiment of the present invention.

FIG. 5 is a conceptual diagram showing a data structure of an EEPROM in which judgment reference values and the like are stored in advance and a flow of the data according to the third embodiment of the present invention.

FIG. 6 is a flowchart illustrating a subroutine for selecting a determination reference value in the distance measuring apparatus according to the third embodiment of the present invention.

FIG. 7 is a conceptual diagram showing a general passive type distance measuring device.

[Explanation of symbols]

1a Central distance measuring means (AF sensor) 1b Peripheral distance measuring means (AF sensor) 2a First reliability data output means 2b Second reliability data output means 3a 1 determining means 3b second determining means 4 calculating means 5 selecting means 15 EEPROM 17 multipoint AF circuit 17a central AF sensor (central distance measuring means) 17b, 17c ... Peripheral AF sensor (peripheral distance measuring means) 24... Photometric unit 36.

Claims (3)

[Claims] 1. A center distance measuring means for measuring a distance in a central portion of a photographing screen and outputting first distance measuring data, and outputting a second distance measuring data by measuring a distance in a peripheral portion of the photographing screen. Peripheral distance measuring means; first reliability data output means for calculating and outputting data representing the reliability of the first distance measurement data; and data representing the reliability of the second distance measurement data. Second reliability data output means for calculating and outputting; comparing the output value of the first reliability data output means with the first reliability determination level value to calculate the first distance measurement data; First determining means for determining whether to enable or disable the second reliability data output means and a second reliability data set to a value stricter than the first reliability determination level value By comparing with the reliability determination level value, it is determined whether the second distance measurement data is valid or invalid. A multi-point ranging device, comprising: a second determining unit for determining the first and second ranging data; and a selecting unit for selecting and outputting desired data from the valid ones of the first and second ranging data. apparatus. 2. The method according to claim 1, wherein the first and second determination means compare a magnitude relationship between an output value of the first and second reliability data output means and the first and second reliability determination level values. ,
When the first and second reliability judgment level values are larger, the distance measurement data is valid, and the first reliability judgment level value is larger than the second reliability judgment level value. The multipoint distance measuring apparatus according to claim 1. 3. The first and second determining means compares a magnitude relationship between an output value of the first and second reliability data output means and the first and second reliability determination level values. ,
When the first and second reliability determination level values are smaller, the distance measurement data is valid, and the first reliability determination level value is smaller than the second reliability determination level value. The multipoint distance measuring apparatus according to claim 1.