JP2001133678A - Automatic multi-point focusing camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resolve the problem of an automatic multi-point focusing camera using a conventional technique being unable to be focused in the case of an object off the center of a photographic picture, because only the distance measurement result of a distance measurement area in the center of the photographic picture is selected to focus the camera and the problem that the camera cannot be focused on the most quickly moving object in the condition of the approaching object, in the case that priority is given to only a distance measurement area, where a slowly moving object exists. SOLUTION: An automatic multi-point focusing camera is provided with an image movement operation part 3, which calculates the speeds and direction of movement of moving subjects, and a distance measurement area selection part 4, which selects a distance measurement area on the basis of maximum and minimum values of the extent of movements, and the camera is provided with a focus direction function which focuses the camera on the distance measurement area, where the most quickly moving subject exists, in the case of subjects approaching the camera focuses the camera on the distance measurement area, where the most slowly moving subject exists, in the case of subjects going away from the camera and thus focuses the camera on the leading part of moving subjects, when focusing the camera on moving subjects.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of arranging a plurality of focus detection areas (ranging points) within a photographing screen, measuring a distance, determining a subject based on the distance measurement result, and focusing the photographing lens. The present invention relates to a multi-point autofocus camera having a focus detection function for performing a focus detection.

[0002]

2. Description of the Related Art A conventional focus detection area (hereinafter, referred to as a distance measuring area or area) is provided near a center of a photographing screen.
Is shifting from spot ranging in which is arranged to a multi-point ranging in which a plurality of ranging areas are arranged in a shooting screen, each is measured, and the closest distance is obtained as a distance measurement result.

In a general multi-point autofocus camera, a distance measuring area is arranged in a line at the center of a photographing screen and on the left and right sides thereof.
There is a specification of a ranging area specification, and a specification of five ranging areas arranged one by one above and below the ranging area in the center of the three ranging areas. Recently, cameras having more ranging areas are available. It has been commercialized and the ranging area tends to increase. In the future, there is a possibility that the camera will be equipped with a distance measurement function in which a distance measurement area is arranged in the entire shooting screen.

In these cameras, when photographing a moving subject in a photographing screen, a focus detection lens is selected by selecting a ranging result obtained from a ranging area where it is determined that the subject is moving. It is common to do.

[0005] Such a multipoint autofocus camera includes:
For example, Japanese Patent Application Laid-Open No. 64-4716 discloses that a ranging area arranged in a screen is divided into several groups,
There is described a technique of selecting a group of a ranging area having the slowest movement from a moving subject and performing focus detection.

In Japanese Patent Application Laid-Open No. Hei 5-11170, the present applicant prohibits distance measurement in a distance measurement area around the subject when it is determined that the subject existing in the photographing screen is a moving subject. We propose the technology to do. According to this technology, a moving object detection operation that requires a plurality of distance measurements and takes a long time is performed before the shutter button is pressed for release, a moving subject is specified, and the distance measurement that detects the moving subject is performed. By measuring the distance only at the point, the time lag of the shutter can be shortened.

Further, in Japanese Patent No. 2756330, when a servo mode (continuous AF, generally a mode for performing moving object prediction AF control that follows a moving object) is set, the center of the photographing screen is set. A technique for selecting a distance measurement area has been proposed. According to this technique, when a moving subject is photographed, the closest subject is not considered to be the main subject to be photographed, and the main subject is located at the center of the photographing screen, and the ranging area is fixed. .

The reason for selecting the center of the photographing screen as the distance measurement area in these prior arts is that when a moving object is shaken by the camera and chases so as to stay within the photographing screen, the subject exists in the center of the screen. Based on the fact that the probability is high, the distance measurement operation on the peripheral side of the shooting screen can be omitted by this technique, and the time lag when the shutter button is pressed can be reduced.

Also, as described above, the center of the photographing screen, that is,
When the distance is measured near the center of the taking lens, the taking lens has a characteristic that the aberration increases as it goes to the peripheral side,
This is advantageous in terms of resolving power as compared with distance measurement around the lens.

Therefore, focusing on a moving subject according to the prior art is excellent in terms of reducing the time lag and increasing the resolution.

[0011]

However, since only the result of distance measurement in the above-described distance measurement area at the center of the photographing screen is selected and focused, an image of an object that does not move constantly or an object that moves in a different direction is shot. If the screen deviates from the center of the screen, it will not be possible to focus accurately.

In addition, when priority is given to a distance measurement area where a slow-moving subject exists, it is not possible to accurately focus on all moving subjects in the photographing screen. Specifically, it is not possible to preferentially select and focus on the fastest moving subject (or a part of the subject) corresponding to the entire ranging area.

The problem of focusing according to the prior art will be described in detail. For example, the scene to be photographed is shown in FIG.
A case where the composition includes a moving subject as shown in FIG.

FIG. 17A shows a scene in which a running train approaches a curve, and FIG. 17B shows an example of an arrangement of 15 distance measurement areas P1 to P15 arranged on a photographing screen. Is shown. In this arrangement example, the correspondence of the distance measurement areas is shown so as to be easily understood in both figures. For example, the center distance measurement area P3 is located at the intersection of the line B and the line D. Distance measurement area P15
Is located at the intersection of line C and line H. here,
A description will be given by taking the center horizontal line B as an example.

As shown in FIG. 17A, in the distance measurement area P1, since the background is measured, the moving speed of the subject detected here is "0".

On the other hand, in the distance measuring areas P2 to P5, the moving distance of the object detected here is measured because the distance of the train is measured. Since the front of the train is closer to the camera, the moving speed detected in each ranging area is as follows.

Distance measuring area P1 = 0 <Distance measuring area P2 <Distance measuring area P3 <Distance measuring area P4 = Distance measuring area P5 JP-A-5-11170 and Patent No. 275
According to the technology described in Japanese Patent No. 6330, when the distance of a moving subject is measured, the distance is measured only in the distance measurement area at the center of the shooting screen, so that the photograph is focused on the distance measurement area P3.

However, since the distance measuring area P3 measures the side surface of the train, the leading end of the train is blurred and becomes a rear focus.

In the technique described in the above-mentioned Japanese Patent Application Laid-Open No. 64-4716, focusing is performed on a distance measurement area where the slowest moving subject exists.
When a selection is made in the distance measurement area where the moving speed is> 0, the photograph is focused on the distance measurement area P2 (the side surface of the train), and the tip of the train is blurred and becomes a photograph of the rear focus, as in the above-mentioned publication. .

Therefore, according to the present invention, a plurality of distance measurement areas (focus detection areas) are arranged in a photographing screen, and when focusing on a moving subject, focusing is performed on the distance measurement area that moves fastest when approaching. However, a focus detection function that can focus on the distance measuring area where the movement is the slowest when moving away from the camera, focuses on the front end of the subject, and obtains a photograph that is not focused on an incomplete position. It is an object to provide a point autofocus camera.

[0021]

According to the present invention, there is provided a multi-point autofocus camera having a plurality of focus detection areas, wherein an image for calculating an amount relating to movement of a subject image in each focus detection area is provided. There is provided a multi-point autofocus camera comprising: a movement calculating means; and a first selection means for preferentially selecting the focus detection area calculated at the image movement calculating means, which has the fastest image movement.

Further, in a multi-point automatic focus camera having a plurality of focus detection areas, an image movement calculation means for calculating an amount of movement of a subject image in each focus detection area, and a calculation result of the image movement calculation means. A distribution output unit that outputs an amount related to a moving speed distribution of the plurality of focus detection regions; and a focus detection region corresponding to a tip end of a moving subject is determined based on an output of the distribution output unit and preferentially. And a second selection means for selecting. The multi-point autofocus camera further includes a moving direction determining unit that determines a moving direction of the subject,
The second selecting means preferentially selects the focus detection area where the image movement is the fastest calculated by the image movement calculating means when the subject is approaching, and when the subject is far away Then, the focus detection area calculated by the image movement calculating means and having the slowest image movement is preferentially selected.

The multi-point autofocus camera having the above-described configuration selects a ranging area based on the maximum value and the minimum value of the moving amount obtained from the moving speed and the moving direction of the moving subject, and moves the moving subject. When focusing on the subject, the focus is on the fastest moving area for moving closer and the moving area is slowest on the slowest moving area for moving away. Let it.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a conceptual block configuration of a distance measuring apparatus for a multipoint autofocus camera according to the present invention. The multi-point autofocus camera includes an AF sensor that outputs a focus detection signal, for example, a focus detection unit 1 including an area sensor, and a focus calculation unit 2 that performs calculations necessary for focus adjustment based on the output focus detection signal. An image movement amount calculator 3 for calculating an amount related to the image movement of the subject based on the calculation result from the focus calculator 2, and a plurality of distance measurement areas based on the output of the image movement amount calculator 3. A focus detection area selection unit 4 for selecting which focus detection area is to be used for focusing, a focus control unit 5 composed of a CPU for controlling focus of these components, and a control signal from the focus control unit 5 And a focus adjustment unit 6 that drives a photographic lens (not shown) to a focused position to achieve a focused state.
The moving amount of the subject calculated by the image moving amount calculating unit 3 may be a moving speed of the subject or a moving direction of the subject.

FIG. 2 is a sectional view of a configuration example applied to a single-lens reflex camera as a multipoint autofocus camera according to the present invention. This camera includes a focus detection unit 11 for detecting a focus at a lower portion of a camera body 10. Normally, the light flux (subject image) that has passed through the photographing lens 12
Is a viewfinder 1 partially above by the main mirror 13.
The light is reflected to the fourth side, and the remaining light flux is transmitted and travels straight. The light beam reflected by the main mirror 13 is guided to a finder 14 via a pentaprism, and enters a viewer's eye as a photographing screen. On the other hand, the light beam transmitted through the main mirror 13 is reflected downward by the sub-mirror 15 integrally attached to the main mirror 13 and guided to the focus detection unit 11.

The focus detecting unit 11 includes a field mask 17 for narrowing the light beam passing through the photographing lens 12, an infrared cut filter 18 for cutting infrared light components, a condenser lens 19 for collecting the light beam, Total reflection mirror 20 for total reflection, and pupil mask 21 for restricting the amount of light beam passing
A re-imaging lens 22 for re-imaging a light beam on a photoelectric conversion element group 26 on an area sensor 23, and a photoelectric conversion element group 2
6 and an area sensor 23 comprising the processing circuit.

At the time of photographing with such a camera, the main mirror 13 and the sub-mirror 15 are raised to the position indicated by the dotted line and retracted, the shutter 24 is opened for a predetermined time, and the light flux (subject image) passing through the photographing lens 12 is The film 25 is exposed.

FIGS. 3A and 3B schematically show an optical system including distance measurement. FIG. 3A illustrates the focus detection unit 11.
1 shows a configuration of a focus detection optical system (a phase difference detection optical system) that guides a light beam (subject image) onto a photoelectric conversion element group 26 of an area sensor 23 in FIG. I have.

The focus detecting optical system includes a photographing lens 12, a field mask 17 for defining a field of view, a condenser lens 19, and an aperture disposed substantially symmetrically with respect to the optical axis of the photographing lens 12 in the optical path. And a pupil mask 21 having portions 21a and 21b.
Behind corresponding to 1b, re-imaging lenses 22a and 22b are provided, respectively. In FIG. 3A, the above-described total reflection mirror 20 is omitted.

In such a configuration, the photographing lens 12
Of the subject that has passed through the areas Ha and Hb of the exit pupil H of the field mask 17 and the condenser lens 1
9. The photoelectric conversion of two areas 23a and 23b in which a large number of photoelectric conversion elements are arranged in the area sensor 23 while passing through the openings 21a and 21b of the pupil mask 21 and the re-imaging lenses 22a and 22b, respectively. The image is re-imaged on the element group 26. For example, if the taking lens 12 is “focused”, that is,
When the subject image 1 is formed thereon, the subject image 1
Condenser lens 19 and re-imaging lenses 22a, 22b
As a result, the image is re-imaged on the photoelectric conversion element group 26 of the area sensor 23, which is a secondary image plane perpendicular to the optical axis O, and becomes a first image I1 and a second image I2 as shown in the figure. .

When the photographing lens 12 is "front-focused",
When the subject image F is formed in front of the imaging plane G, the subject images F are re-imaged perpendicularly to the optical axis O in a form closer to the optical axis O, and the first images F1, Second image F2
Becomes

Further, when the photographing lens 12 forms a subject image R behind the focus, that is, behind the image forming plane G, the subject images R are separated from the optical axis O with respect to the optical axis O by being separated from each other. The first image R1 and the second image R2 are vertically re-imaged.
Becomes Accordingly, by detecting and measuring the distance between the first image and the second image, the in-focus state of the photographing lens 12 can be detected including the front focus and the rear focus. More specifically, the light intensity distributions of the first image and the second image are obtained from the output of the subject image data corresponding to the area sensor 23 (openings 23a and 23b) so that the interval between the two images can be measured. It is configured.

FIG. 4 shows functional blocks including the electric control system of the camera described in FIG. 2, and the detailed configuration and operation of each unit will be described. In this configuration, the control unit 30 performs overall control of the entire camera,
An arithmetic / processing unit 31 including, for example, a CPU is provided therein.
, ROM 32, RAM 33, A / D converter 3
4 is provided.

The control unit 30 controls a series of operations of the camera according to a camera sequence program (described in detail later) stored in the ROM 32. EEPROM35
Can store and hold correction data relating to AF control, photometry, etc., as information unique to each camera body. Further, the control unit 30 includes an area sensor 23, a lens driving unit 33, an encoder 37, a photometry unit 39, a shutter driving unit 40, an aperture driving unit 41, and a film driving unit 42.
Are connected to the control unit 30 so as to be able to communicate with each other.

In such a configuration, the lens driving unit 3
6 drives the focusing lens 12a of the taking lens 12 with the motor ML38 based on the control of the control unit 30. At this time, the encoder 37 generates a pulse corresponding to the moving amount of the focusing lens 12a, and
And the lens drive is appropriately controlled.

Further, the photometric unit 39 is provided with an S
It has a PD (silicon photodiode) and generates an output according to the luminance of the subject. The control unit 30 converts the photometric result of the photometric unit 39 into a digital signal by the A / D converter 34 and stores the photometric value in the RAM 33.

Shutter drive section 40 and aperture drive section 41
Is operated by a predetermined control signal from the control unit 30, and drives a shutter mechanism and an aperture mechanism (not shown) to expose the film surface.

The film driving section 42 performs automatic loading of the film according to a predetermined control signal from the control section 30.
Perform the winding and rewinding operations. A first release switch (hereinafter, referred to as 1RSW) and a second release switch (hereinafter, referred to as 2RSW) are switches interlocked with a release button. Subsequently, the 2RSW is turned on by the pressing operation in the second stage. Control unit 3
0 means metering and AF (auto focus) with 1RSW on
Each part is appropriately controlled such that the exposure operation and the film winding operation are performed when the 2RSW is turned on.

FIG. 5 shows a specific circuit configuration of the area sensor 23 described above.

The pixel section (that is, the photoelectric conversion element group 26) of the area sensor 23 is composed of a large number of pixel units 51 regularly arranged in a matrix.

In this configuration, the accumulation control section 52 controls the accumulation operation of the pixel section according to a control signal from the control section 30. The output V0 of each pixel unit 51 is selected by a vertical shift register 53 and a horizontal shift register 54 and input to a buffer 55. And this buffer 5
The output SDATA of No. 5 is input to an A / D converter 34 in the control unit 30 and is A / D converted.

The output VM of each pixel unit 51 is connected to the output VM of a predetermined plurality of pixel units 51, and is input to the buffer 55 via the switches MSL1 to MSLn.

Then, in the distance measurement area 56, the potential at the point M to which the outputs VMn of the plurality of pixel units 51 are connected generates a potential corresponding to the peak value of the outputs VMn in the plurality of pixel units 51. And the pixel unit 51
Constitute a peak detection circuit that outputs these. Therefore, when the switches MSL <b> 1 to MSLn are sequentially turned on, the potential corresponding to the peak value in each ranging area 56 can be monitored via the buffer 55. The output VP of the buffer 55 is input from the terminal MDATA to the A / D converter 34 in the control unit 30.
A / D conversion is performed.

FIG. 6 shows the pixel unit 51 described above.
Is shown below. This pixel unit 51
It comprises a photodiode 61 functioning as a photoelectric conversion element, a capacitor 62, an amplifier 63, switches 64 and 65, and an NMOS transistor 66.

An amplifier 63 is connected to an output side of the photodiode 61, and a capacitor 62 is connected to an input / output terminal of the amplifier 63, and accumulates charges generated in the photodiode 61.

The output side of the amplifier 63 receives the signal X from the vertical shift register 53 and the horizontal shift register 54.
n and Yn are connected to an output terminal (output V0) via switches 64 and 65 connected in series for switching on and off, respectively.

The output side of the amplifier 63 is connected to the gate of an NMOS transistor 66 whose drain is connected to a fixed voltage, and the source of the NMOS transistor is connected to a monitor output terminal (monitor output VM).

In such a circuit configuration, the amplifier 63
Is changed in a direction in which the potential increases as the storage amount of the capacitor 62 increases. Since the outputs of the plurality of pixel units 51 are connected to each other in the monitor output VM, a potential indicating the peak value of the accumulated amount is generated. In this way, each pixel unit 51 performs photoelectric conversion and supplies an output as an element corresponding to the distance measurement area to the above-described image movement amount calculation unit 3.

Next, FIG. 7 shows an example of the arrangement of the respective distance measurement areas P1 to Pn constituting the focus detection area in the photographing screen. The above-described switches MSL1 to MSLn are connected to each of the distance measurement areas P
1 to Pn, respectively, for example, when one switch MSLm of the switches MSL1 to MSLn is turned on, the corresponding distance measurement area Pm
Is selected and the monitor terminal MDATA is selected.
Output to

For example, when a plurality of switches are turned on, peak values in the plurality of distance measurement areas can be monitored. For example, when all the switches MSL1 to MSLn are turned on, the peak value in the entire distance measurement area of the area sensor 23 can be output from the MDATA terminal and monitored.

The accumulation operation of the area sensor 23 will be described with reference to a time chart shown in FIG.
Here, a description will be given by taking the distance measurement areas P5, P6, and P7 in the shooting screen as an example. The control unit 30 controls the area sensor 23
After the accumulation operation is started by the accumulation start signal (INTS), the peak value is sequentially referred to for each of the distance measurement areas. At this time, priority is given to the ranging area that reaches the appropriate accumulation level the fastest, and when the peak value of the ranging area reaches the appropriate accumulation level, the accumulation end signal (INTE)
To terminate the accumulation operation for each ranging area.

That is, as shown in FIGS. 9A and 9B, the two area sensors 23 constituting the area sensor
The accumulation operation ends simultaneously for the distance measurement areas corresponding to a and 23b, for example, a5 and b5 corresponding to the distance measurement area P5. That is, accumulation operations of am, bm, (1 ≦ m ≦ n) corresponding to a certain ranging area are sequentially performed on all ranging areas.

With respect to one of the distance measuring areas m of am and bm, the arrangement of the photodiodes 61 corresponding thereto is shown linearly in FIGS.

The photodiode array am forming the right area sensor 23a has L (1), L (2), L (3),.
L (64), and the subject image signals are sequentially processed. Similarly, the photodiode array bm forming the left area sensor 23b has R (1), R (2), R (3),.
R (64), and the subject image signal is sequentially processed.

Therefore, the control unit 30 controls each unit as follows to detect a subject image as data. That is,
The control unit 30 sends the read clock C to the area sensor 23.
When LK is input, the terminal SD of the area sensor 23 is input.
Sensor data, which is a subject image signal, is sequentially output from the ATA. Therefore, the A / D converter 34 in the control unit 30
A / D-converts this sensor data into
2 sequentially. In this way, the control unit 30 can specify, for example, a certain ranging area and read out only the sensor data corresponding to the ranging area.

Next, an AF detection calculation based on the subject image data obtained as described above will be described. For example, in this embodiment, there is a method of performing two types of correlation calculations. One of the methods is a method in which a correlation operation is performed between the first subject image and the second subject image divided by the focus detection optical system, and a shift amount between the two images (referred to as “image shift amount”) is obtained. . The other method is a method in which a correlation operation is performed between the subject image at time t0 and the subject image at time t1 to obtain the movement amount of the subject image.

(I) Correlation calculation for obtaining image shift amount: First, the correlation calculation for obtaining the image shift amount between the first subject image and the second subject image will be described. 23a and 23b can be generally expressed in the form of L (i, j) and R (i, j), respectively.

In the following description, a pair of distance measurement areas corresponding to the area sensors 23a and 23b, that is, one-dimensional subject image data are respectively represented by L (I) and R (I) (I = 1 to 1) for easy understanding. k) (see FIG. 10). Here, in the present embodiment, assuming that k = 64, a description will be given based on the processing procedure relating to the “image shift amount detection” routine with reference to the flowchart shown in FIG.

First, respective initial values of variables SL, SR and FMIN are set (step S1). Here, S
L ← 5, SR ← 37, FMIN = FMIN 0 are set.

Next, 8 is input as the initial value of the loop variable J (step S2), and the correlation calculation of equation (1) is performed to obtain the correlation value F (s) (step S3).

F (s) = Σ | L (SL + I) −R (SR + I) | (1) (where s = SL−SR, I = 0 to 26) where the variables SL and SR are respectively Subject image data L
A variable indicating the head position of the block for which the correlation operation is performed among (I) and R (I), and a variable J for storing the number of shifts of the block on the subject image data R (I), and The number of data is 27.

Next, the correlation value F (s) is compared with FMIN (initial value FMIN 0 at first, and initial or updated value after the second time) (step S4). In this comparison, if F (s) is smaller (YES), FMIN is changed to F
(S) is updated, and SLM and SRM are updated to SLSR (step S5).

On the other hand, in the comparison in step S4, FMIN
Is smaller than the correlation value F (s) (NO), SR,
The next block is set by subtracting 1 from J (step S6). Then, it is determined whether or not J = 0 (step S7). If it is not 0 (NO), the process returns to step S3 to repeat the same correlation calculation. As described above, the block in the object image data L (I) is fixed, and the block in the object image R (I) is shifted by one element at a time to perform the correlation operation.

On the other hand, in the determination in step S7,
If J is 0 (YES), 4 and 3 are added to the variables SL and SR, respectively, and the next block is set (step S8). Next, it is determined whether or not SL = 29 (step S9).
O), the process returns to step S2 to continue the above-described correlation calculation. However, if SL = 29 (YES), the correlation calculation ends. Thus, the subject image data L
A block for performing the correlation operation is set on (I) and R (I), and the correlation operation is repeatedly performed. As a result of the correlation calculation of each block obtained as a result, the correlation value F (s) becomes the minimum at the shift amount s = x where the correlation of the subject image data is the highest. At this time, SL and SR at the time of the minimum correlation value F (x) are stored in SLM and SRM.

Next, the following correlation values FM and FP at shift positions before and after the minimum correlation value F (x) used for calculating a reliability index described later are obtained (step S10).

[0066]

(Equation 1)

Then, a reliability index SK for determining the reliability of the correlation operation is calculated (step S11). This reliability index SK is calculated by adding the sum of the minimum correlation value F (x) and the second smallest correlation value FP (or FM) to a value (FM-F (x) or FP-F (x) corresponding to the contrast of the subject data. ))
This is a numerical value standardized by Equation (4) or Equation (5).

[0068]

(Equation 2)

Next, it is determined whether or not the reliability index SK is equal to or larger than a predetermined value α (step S12). If SK is equal to or larger than α (YES), it is determined that the reliability is low, and the detection impossible flag is set. Set (step S13). On the other hand, if SK is less than α (NO), it is determined that there is reliability, and
The image shift amount ΔZ is calculated (step S14). For example, 3
The minimum value F for continuous correlation using the point interpolation technique
The shift amount x0 that gives MIN = F (x0) is obtained by the following equation.

(Equation 3)

Using the shift amount x0, the image shift amount ΔZ can be obtained by equation (8). ΔZ = x0−ΔZ0 (8) (However, ΔZ0 is an image shift amount during focusing).

From the image shift amount ΔZ obtained by the above equation, the defocus amount ΔD of the subject image plane with respect to the expected focal plane can be obtained by the equation (9).

(Equation 4)

The defocus amount is calculated for each of the plurality of ranging areas selected in this way. Then, for example, a defocus amount indicating the shortest distance is selected from a plurality of distance measurement areas.

Further, the lens driving amount ΔL is obtained from the selected defocus amount ΔD by the equation (10).

(Equation 5)

By driving the focus lens based on the lens drive amount ΔL, a focused state can be obtained.

(II) Principle for Predicting Subject Image Position: The principle of focus detection for a moving subject shown in FIGS. 12A to 12D will be described.

Referring to FIG. 12, the relationship between the subject 66, the camera 10, and the area sensor 23 is shown in FIG.
As shown in FIG.
In the case where 6 approaches straight (in the direction of arrow G3), the first and second subject images on the first (L) and second sensors (R) are shifted from time t0 to time by the above-described principle of focus detection. They move outward from each other during t1. In this case, the movement amounts ΔXL and ΔXR of the subject image are equal.

As shown in FIG. 12B, when the subject 66 moves parallel to the camera 10 in the horizontal direction (the direction of arrow G1) perpendicular to the optical axis, the two subject images move in the same direction. I do. In this case, the moving amount ΔXL of the subject image
And ΔXR are equal.

Further, as shown in FIG. 12C, the subject 66 approaches the camera 10 toward the left (arrow G).
In the case of four directions), the amount of movement of the first subject image (L) toward the outside due to approaching and the amount of movement to the left due to parallel movement to the left are offset, and the amount of movement is reduced.

Similarly, when the subject 66 moves to the rear left toward the camera 10 as shown in FIG.
The amount of movement of the first subject image (L) inward by moving away from the first object image (L) and the amount of movement leftward by moving in parallel to the left are offset, and the amount of movement is reduced. On the other hand, the amount of movement of the second subject image (R) toward the inside by moving away from it and the amount of movement to the left due to the parallel movement to the left are added to increase the amount of movement.

Here, based on the subject images from time t0 to time t1, the moving amounts .DELTA.XL and .DELTA.XR of the first and second subject images are detected by means for performing a correlation operation and the like, which will be described later, and are moved to the right. When the sign of + is given, the moving amount of the subject image in the optical axis direction can be obtained by ΔXR−ΔXL, and the moving amount of the lateral subject image can be obtained by ΔXR + ΔXL. Therefore,
The movement amount ΔXR of the subject image from time t0 to time t1,
If ΔXL is obtained, the position of the subject image at time t2 can be predicted.

Assuming that the subject is moving at a constant speed, the moving speed of the subject image in the horizontal direction is constant. still,
The moving speed of the subject image in the optical axis direction is not strictly a constant speed, but may be considered as a constant speed at a minute time interval. Therefore, the predicted position of the first subject image at time t0 is
ΔX shown in Expression (11) from the subject image position at time t1
L 'has moved. That is,

(Equation 6)

Similarly, the predicted position of the second subject image is given by the equation (1)
It moves by ΔXR ′ shown in 2).

[0083]

(Equation 7)

If the image shift amount of the first and second subject images at time t1 is ΔZ, the predicted image shift amount ΔZ 'at time t2 is
Is obtained as in Expression (13).

(Equation 8)

The lens driving amount is obtained based on the predicted image shift amount ΔZ '. By setting the time t2 to the time until the start of exposure, a photograph in focus on a moving subject can be obtained. At this time, ΔXR−Δ
Based on the sign of XL, it is determined whether the subject is approaching or moving away. If ΔXR−ΔXL> 0, the subject is approaching.

Next, the correlation calculation for obtaining the movement of the subject image and the reliability determination thereof will be described.
Blocks SLM 'and SR obtained by the above-described correlation operation between the subject images L' (I) and R '(I) and the two images.
M ′, the correlation coefficient SK ′, and the image shift amount ΔZ ′ are:
It is stored in the RAM 42 in the controller 40. Thereafter, subject image signals L (I) and R (I) at time t1 are detected.

Next, the movement amount detection will be described with reference to the movement of the subject image shown in FIG. 13 and the flowchart shown in FIG.

First, for the first object image signal, a correlation operation is performed between the object image signal L '(I) at time t0 and the object image signal L (I) at time t1. In the "movement amount detection" routine for detecting the movement of the subject image, first, SLM'-10 is substituted for a variable SL (step S21), and a variable J is a variable for counting the correlation range. And substitute 20 (step S2
2).

Next, the correlation output F (s) is calculated by the correlation equation (14) (step S23).

[0090]

(Equation 9)

Subsequently, similarly to the above-described correlation operation, F
(S) is compared with FMIN (step S24). In this comparison, if F (s) is smaller than FMIN (YES), FMI
F (s) is substituted for N, and SL is stored in SLM (step S25). In this case, the number of elements in the block to be correlated is 27, which is the same as the number of elements in the block when the image shift amount is obtained. However, if F (s) is larger than FMIN (NO), the process moves to the next step S26.

Next, 1 is added to SL, and 1 is subtracted from J (step S26). Then, it is determined whether or not J = 0. If J is not 0 (NO), the process returns to step S23 until J = 0, and the correlation equation F (s) is repeated. As described above, the correlation is obtained by changing the correlation range up to ± 10 elements. The correlation range is determined by the movement amount range to be detected. However, when J = 0 (YE
S), the reliability is determined.

That is, the correlation values FM and FP at the shift amounts before and after the minimum correlation value F (X) are calculated by using the equations (15) and (15) in the same manner as when the image shift amounts of the first and second object images are obtained. It is determined by equation (16) (step S28).

[0094]

(Equation 10)

Next, the reliability index SK is calculated using the above-mentioned equation (4).
And equation (5) (step S29). And
It is determined whether or not SK> β (step S30). When SK ≦ β in this determination (NO), it is determined that there is reliability, and
The movement amount is obtained (step S31). However, the value β is set to a value larger than the determination value α when the image shift amounts of the first and second subject images are obtained. This is because the waveform is often deformed when the subject is moving, so that the correlation is likely to be deteriorated.

Then, the movement amount ΔXL of the subject image is obtained. Equations (17) and (1) are calculated by a three-point interpolation method in the same manner as when calculating the image shift amounts of the first and second object images.
Determined by 8).

[Equation 11]

On the other hand, if it is determined in step S30 that SK> β (YES), it is determined that there is no reliability, and an undetectable flag is set (step S3).
1).

The details of the second subject images R (I) and R '(I) are also omitted, but a similar movement amount detection routine is executed, and the block position SRM and the movement amount ΔX having the highest correlation are executed.
Find R. The movement amounts ΔXL, Δ of the first and second object images
When XR is obtained, the image shift amount ΔZ 'at time t1 is
It is obtained from the image shift amount ΔZ at the time t0 as in Expression (19).

(Equation 12)

At time t based on the image shift amount ΔZ at time t0
The prediction formula of the image shift amount ΔZ ″ in Equation (2) is as shown in Expression (20).

(Equation 13)

The time t2 is obtained by a method described later, and ΔZ ″
At the time t2 by driving the lens by the amount based on
In, it is possible to focus on a moving subject.

Incidentally, the moving speed v of the object image = (ΔXR−
If [.DELTA.XL) / (t1-t0) is too large, the detection value is considered unreliable, and the image shift amount is not predicted. When the moving speed of the subject image is small and regarded as a detection error, the moving speed is set to zero.

(III) Prediction formula of image shift amount prediction time t2: A method of obtaining the time t2 at which the image shift amount is predicted will be described. As described above, the image shift amount ΔZ ″ at time t2 is the image shift amount ΔZ at time t1,
Equation (2) using the movement amounts ΔXR and ΔXL of the subject image of No. 1
0).

Now, the time t2 at which the subject is brought into a focused state at the time of exposure is obtained by equation (21).

[Equation 14]

In this equation, td is the time from the time t1 to the start of lens driving, and this value includes the processing time inside the camera such as the above-described correlation operation time. Here, ke is a conversion coefficient for obtaining a lens driving time proportional to the image shift amount ΔZ ″. The lens driving amount ΔL
Are given by the equations (9) and (10) based on the image shift amount ΔZ ″.
In a region where the image shift amount ΔZ ″ is sufficiently small, the defocus amount ΔD and the lens drive amount ΔL are approximately proportional to the image shift amount ΔZ ″, so there is no problem in accuracy. te is the time from the end of lens driving to the start of exposure after the shutter curtain is opened, and includes the time for camera exposure calculation, aperture control, mirror up, and the like.

By solving the above equations (20) and (21), the equation (22) for obtaining the predicted image shift amount is derived as follows.

(Equation 15)

From this ΔZ ″, equations (9) and (10)
By obtaining the lens drive amount ΔL and driving the lens, the moving subject can be brought into a focused state at the time of exposure.

Next, the time t2 at which the lens is brought into focus at the end of driving the lens is obtained by equation (23). t2 = t1 + td + ke · ΔZ ″ (23) Similarly, by solving the equations (20) and (23), the following equation (24) is derived.

(Equation 16) By obtaining the lens drive amount ΔL from Equation (9) and Equation (10) from ΔZ ″ and driving the lens, the moving subject can be brought into the focused state at the end of lens drive. .

Next, a specific operation program in this embodiment will be described with reference to the flowchart shown in FIG. Note that the “AF detection” routine is repeatedly executed while the power of the camera is on. First, the integration operation of the area sensor 23 is performed, and when the integration is completed, subject image data (hereinafter, referred to as sensor data) is read from the area sensor 23 (step S41).

Next, it is determined whether or not the object image shift amount (hereinafter, image shift amount) has been detected (step S42). If it is not detected in this determination (NO), the image shift amount is obtained by the above-described "image shift amount detection" routine (see FIG. 11) (step S43). Here, the area sensor 2
An image shift amount is detected for a predetermined distance measuring area set in advance on 3a and 23b. However, the preset ranging area may be, for example, one ranging area selected by the photographer or all ranging areas.

Next, it is determined whether or not the detection of the image shift amount has been completed for all the predetermined distance measurement areas (step S).
44) If not completed yet (NO), the flow returns to step S43 to detect the amount of image shift in the next ranging area. On the other hand, when the image shift amount detection for all the predetermined distance measurement areas is completed (YES), the distance measurement area is selected based on a predetermined algorithm, for example, the closest selection (step S45). Hereinafter, the description will be given assuming that the selected distance measurement areas am and bm are used.

Next, it is determined whether or not the image shift amount cannot be detected, that is, whether or not all the predetermined distance measurement areas cannot be detected (step S46). In this determination, if the image can be detected (YES), the image shift amount detectable flag is set (step S47), and the image shift amount detected flag is set (step S48).

On the other hand, if it is determined in step S46 that all the images cannot be detected (NO), the image shift amount undetectable flag is set (step S49), and the image shift amount detected flag is cleared (step S49). S50). Then, after setting or clearing the image shift amount detected flag, the image shift amount detected flag is cleared (step S).
51), and return to the main routine described later with reference to FIG. If the image shift amount has already been detected in the determination in step S42 (YES), the movement amount of the object image with respect to time is detected for each of the first and second object images as described below. First, the distance measuring area am selected in step S45 is set as an initial distance measuring area (step S52).

Next, for the first subject image in the distance measurement area am, correlation calculation is performed between the sensor data stored in the previous (time t0) image shift amount detection and the current (time t1) sensor data. , The amount of movement is detected (step S5)
3). This is based on the movement amount detection routine shown in FIG.

Then, it is determined whether or not the movement amount of the first subject image has been detected (step S54). In this judgment,
If the movement amount cannot be detected (NO), the first and second
The image shift amount between the subject images is set to 0, and it is determined whether or not all the distance measurement areas have been set for the distance measurement areas near the distance measurement area am (step S55).
If it is determined in this determination that the shift has not been completed for all the neighboring ranging areas (NO), the ranging area at this time (time t1) is shifted according to a predetermined order, and shifted to the next ranging area. It is set (step S56). still,
Here, the predetermined order is, as shown in FIG. 16 (a) to (e), a horizontal direction near an an as shown by an arrow centering on the initial distance measurement area an on the area sensor 23a. And shifting the ranging area in the vertical direction. The reason why the processing is performed in such an order is to cope with the movement of the subject image on the area sensor 23 in the horizontal direction and the vertical direction due to the vertical movement and the horizontal movement of the subject. That is, the image movement of the subject is detected including the distance measurement area near an. Thereafter, the process returns to step S53, and the first subject image movement amount is detected again for the new distance measurement area that has been set. Thus, the position of the first subject image is searched.

However, if it is determined in step S55 that the setting has been completed in all the nearby distance measuring areas (YES), the process proceeds to step 59 described later. In the determination in step S54, if the position of the first object image can be detected and the movement amount from time t0 to time t1 can be detected (YES), the distance measurement area ak in which the first object movement amount can be detected is set. The movement amount of the corresponding distance measurement area bk of the area sensor 23b with respect to the second subject image is detected (step S57). This refers to the “movement amount detection” routine of FIG. At this time, the distance measurement area at time t1 when the movement amount of the first subject image can be detected is represented by a
k.

Here, when the shift of the distance measurement area occurs, the shift amount between the distance measurement areas (for example, the pixel number conversion value of the center distance) is added to ΔXL and ΔXR as the image movement amount.

When the amounts of movement of both the first and second object images have been detected in this way, the moving speed v of the object image in the optical axis direction is calculated from the following equation (step S5).
8).

[Equation 17]

Then, it is determined whether or not all the moving speed calculations have been completed for the predetermined distance measurement area to be detected (step S59). If the calculations have not been completed (NO),
Since the detection of the moving speed has been completed for the distance measurement area an, the distance measurement area an + 1 is set next (step S60), and the process returns to step S53.

If it is determined in step S59 that all the moving speed calculations have been completed (YES), the calculated moving speed v is compared with a predetermined speed vth, and the object moves in the optical axis direction. It is determined whether or not the object is moving in the entire distance measurement area (step S61). If it can be determined that the object is moving in the optical axis direction (moving object determination) (YES), a subject moving flag is set (step S62). However, if it is determined that the subject is not moving (NO), the subject moving flag is cleared (step S63), and the above-described step S63 is performed.
Returning to step 43, the processing for detecting the amount of image shift is performed again.

Then, after setting the above-described subject moving flag, an image movement detected flag is set (step S64), and a focus detection area to be focused upon when a moving subject is detected is selected according to an algorithm described later (step S64). Step S65), and return to the main routine.

Next, the main routine of a camera to which the multipoint autofocus camera of the present invention is applied will be described with reference to the configuration shown in FIG. 4 and the flowchart shown in FIG.
This main operation is a routine showing a control procedure of a program started by the control unit 30, and is executed when the operation of the control unit 30 starts.

First, various correction data used in the distance measurement and photometry processing stored in advance from the EEPROM 35 are read out and loaded into the RAM 33 (step S7).
1). Then, it is determined whether or not 1RSW is turned on (step S72), and if it is not on (NO),
It is determined whether or not a switch other than 1RSW and 2RSW is operated (step S73), and if there is an operated switch (YES), a process corresponding to the switch is executed (step S74). Step S7
Return to 2.

On the other hand, in step S72, 1R
If the switch is on (YES), it is determined whether the AF operation mode is “single AF” (step S7).
5). If it is determined that the single AF mode has been set (YES), the focus is locked once the lens is in focus and the lens is not driven. Therefore, it is determined whether or not the lens has been focused (step S76). However, if the AF mode is not the single AF mode (NO), it is considered that the AF mode is the continuous AF mode. The process moves to step S77.

If it is determined in step S76 that focusing has been completed (YES), AF driving is not performed and the process returns to step S72. However, if it is out of focus (NO),
Alternatively, in the case of the continuous AF mode, it is determined whether or not the photometry has been performed (step S77). If the photometry has not been performed, the photometry unit 39 is operated to determine the exposure amount and the subject brightness is measured. (Step S7)
8).

Next, the above-described subroutine "AF detection"
Is executed (step S79). As a result of this AF operation, it is determined whether or not an image shift cannot be detected with reference to the above-described detection impossible flag (step S80). If the image shift can be detected (NO), it is determined whether or not the movement amount of the subject image has been detected (step S81). On the other hand, when the image shift cannot be detected (YES), the focus lens 1
While driving 2a, a scan operation for searching for a lens position where AF detection is possible is performed (step S82), and the process returns to step S72. When this scan is performed, all flags are cleared and AF detection is restarted from the beginning.

In step S81, when the moving amount of the subject image has been detected (YES), the image shift amount is predicted. First, it is determined whether or not the 2RSW is turned on (step S83). If the 2RSW is turned on (YES), an image shift amount at the start of exposure is predicted (step S84). On the other hand, if the 2RSW is off (NO), only the AF operation is performed, so that the image shift amount at the end of the lens driving is predicted (step S8).
5) The process proceeds to the in-focus determination in step S87 described below.

If the movement amount of the subject image has not been detected in step S81 (NO), it is determined whether the subject is moving (step S86). At this point, the image movement detected flag is cleared after the lens is driven (step S87), as described later, and after the lens is driven in the continuous AF mode, the subject moving flag is set even if the image movement is not detected. Is set, the flow returns to step S72, and the movement of the subject image is detected again.

On the other hand, if the image is not moving (NO), the detected image shift amount or the predicted image shift amount is converted into a defocus amount, and whether or not the image is within the focus allowable range is determined. Is determined (step S87). If it is not determined that the lens is in focus, a necessary lens drive amount is obtained, and the focus lens is driven (step S88). In the lens driving routine, the image shift detection completed flag, the image shift undetectable flag, and the image movement detected flag are cleared after the lens is driven. In this clearing process, it is considered that the subject image greatly changes after the focus lens is once driven.
This is to restart the detection from the beginning. As described above, only the subject image moving flag is not cleared here. The reason for this is to prevent the in-focus determination from being performed in the first AF detection after driving the lens in the continuous AF mode, and to continuously detect the movement of the subject.

If it is determined in step S87 that the camera is in focus (YES), the on / off state of the 2RSW is determined (step S89). If the 2RSW is turned on (YES), the exposure operation is performed by controlling the aperture and the shutter based on the photometric value stored in the RAM 33 (step S90). Then, the photographed film is wound up and fed to the position of the next frame (step S91), and a series of photographing operations ends.

As described above, in the first embodiment, the position of the subject image is detected on the area sensor in both the image division direction and the direction perpendicular to the image division direction. Even in the case of a moving subject that moves in the left and right directions, the position of the subject image can be detected, and predictive control can be performed, so that accurate focusing can be achieved.

Next, with reference to the flowchart shown in FIG. 19, description will be made on the selection of the distance measurement area when the subject is a moving object in step S65 shown in FIG.

First, an initial ranging area is set (step S101). For example, the distance measurement area P1 shown in FIG.
Set.

Next, it is determined whether or not image movement can be detected in the set distance measuring area (step S10).
2). If the image movement can be detected by this determination (YE
S), it is determined whether or not the image moving speed detected in the set distance measurement area exceeds a maximum limit value (image moving speed> maximum limit value) (step S103). This maximum limit is determined by the moving object focusing performance of the camera,
35. Therefore, if the image moving speed exceeds this limit value, focusing cannot be performed.

If the image moving speed does not exceed the maximum limit value (NO), it is determined whether or not the image moving speed detected in the set distance measuring area is the highest so far (see FIG. 13). Step S104).

If the image movement speed is the maximum so far (YES), this distance measurement area is stored in the RAM 33, and it is determined whether or not the setting of all the distance measurement areas has been completed (step S106). .

On the other hand, if the image movement cannot be detected (NO) in the above-mentioned determination in step S102, step S1 is executed.
If the image moving speed exceeds the maximum limit value in the judgment of 03 (YES), and if the image moving speed has not been the highest so far in the judgment of step S104 (NO), the process proceeds to step S106.

If it is determined in step S106 that the setting of all the distance measurement areas is completed (YES), since the maximum moving speed within the limit value has been detected, the distance measurement area is set as the selected distance measurement area. Set (Step S10
7) Return to the main routine. However, if it is determined in step S106 that the setting of all the ranging areas has not been completed (NO), the next ranging area is set (step S108), and the process returns to step S102.

As described above, as an effect of the first embodiment, it is possible to focus on the moving object located at the foreground in the shooting screen.

Next, a second embodiment according to the multipoint autofocus camera of the present invention will be described.

In the above-described first embodiment, by selecting the ranging area where the maximum moving speed is detected, the tip of the moving subject (the front of the train) in the composition example shown in FIG. 17 is focused. I was In this second embodiment,
The speed distribution of the entire ranging area is obtained, and the selected ranging area is changed according to the moving direction of the subject.

Referring to FIG. 20, a description will be given of the speed distribution of the entire ranging area and the change of the speed distribution. FIG.
(A) to (c) of FIG. 17 show, for example, a distance measurement area divided into 25 distance measurement areas as shown in FIG.
15 shows an example of the velocity distribution calculated in step S58 of FIG. 15 when the composition shown in FIG.

First, in FIG. 20 (a), since the distance measurement areas P1 to P5 and the distance measurement areas P21 to P25 measure the background, the moving speed is "0" and the distance measurement area P6. , P7, P10, P11, P15, P16, P20
Also, the moving speed is "0" because the upper and lower areas of the train are measured.

Other distance measuring areas P8, P9, P12,
Since P13, P14, P17, P18, and P19 are areas where a moving train is present, the moving speeds V1 to V3 are measured.

Here, the moving speed V3 of the ranging area that captures the head of the train that is close to the camera becomes the maximum, and the speed V1 of the ranging area that captures the image from the side to the tail of the train becomes the minimum. Become.

FIG. 20 (b) shows an example of the speed distribution after time t1 from FIG. 20 (a), that is, a scene in which the train comes closer to the camera. For this reason, FIG.
In the distance measuring areas P22 and P2 where the moving speed was "0"
3, P24 sharply changes to the moving speed V4. FIG.
(C) is an example of the velocity distribution after time t2 from FIG. 20 (a). However, t1 <t2.

Since the train shown in FIG. 17A is moving to the right side of the drawing, the distance measurement area where the speed is observed also moves to the right. In addition, since the train gradually approaches the camera, the moving speed gradually increases. If the train is moving to the left side of the page, the reverse is true.

Next, referring to the flowchart shown in FIG. 21, the description will be given of the selection of the moving object distance measuring area in the step S65 shown in FIG. 15 in the second embodiment. Other routines in the second embodiment are the same as those in the other flowcharts in the first embodiment, and a description thereof will not be repeated.

First, an initial ranging area is set (step S111). For example, the distance measurement area P1 shown in FIG.
Set.

Next, it is determined whether or not image movement can be detected in the set distance measuring area (step S11).
2). If the image movement can be detected by this determination (YE
S), it is determined whether or not the image moving speed detected in the set distance measurement area exceeds a maximum limit value (image moving speed> maximum limit value) (step S113). This maximum limit is determined by the moving object focusing performance of the camera,
35. Therefore, if the image moving speed exceeds this limit value, focusing cannot be performed.

In this determination, if the image moving speed is less than the maximum limit value (NO), focusing is possible, so that the image moving speed detected next in the ranging area is the minimum limit value (image moving speed <minimum). (The limit value) is determined (step S114). This determination value is almost the same as the movement determination value in step S61 in FIG. 15, and is a reference value for determining whether or not it is possible to move. If the image movement speed exceeds the minimum limit value in this determination (NO), that is, if it is determined that the subject is a moving subject, it is determined whether the image movement speed is the minimum value ( Step S115). If the image moving speed is not the minimum value (NO), it is determined whether the image moving speed is the maximum value (step S).
116) If this image movement speed is the maximum value (YE
S), the image moving speed is stored as the maximum distance measuring area (step S117). On the other hand, step S115
If the image movement speed is the minimum value in the determination of
S), the image moving speed is stored as the minimum distance measurement area (step S118).

After storing these distance measurement areas, it is determined whether or not the setting of all the distance measurement areas has been completed (step S).
119).

On the other hand, if the image movement cannot be detected in the determination in step S112 (NO), the process proceeds to step S113.
If the image movement speed exceeds the maximum limit value in the determination of (Y)
ES), when the moving speed is less than the minimum limit value in the determination in the step S114 (YES), or when the image moving speed is not the maximum value in the determination in the step S116 (NO), respectively. The process moves to S119.

If it is determined in step S119 that the setting of all the ranging areas has not been completed (NO), the next ranging area is set (step S120), and the process returns to step S112. However, when the setting of all the distance measurement areas is completed (YES), it is determined whether or not the subject is approaching the camera (step S121).

In this determination, if the subject is approaching (YES), the distance measuring area in which the maximum moving speed is detected is set as the selected distance measuring area (step S12).
2). However, when the subject is moving away (N
O), the distance measuring area in which the minimum moving speed is detected is set as the selected distance measuring area (step S123).

Then, after each setting, the process returns to the main routine.

According to the present embodiment, it is possible to detect the moving direction and the moving speed of the moving subject, and focus on the end of the subject having the maximum value or the minimum value.

As a modification of the second embodiment, a plurality of line sensors may be arranged and used instead of a single light receiving element for an area sensor. In each of the embodiments described above, an example in which all the 15 ranging areas are used has been described. However, from the viewpoint of shortening the time lag, the ranging area to be used may be thinned out according to a set shooting mode or the like. Good.

For example, when the shutter priority mode or the like is set, thinning out of a distance measurement area or the like arranged around a shooting screen is performed according to a shutter speed set for shooting a slow moving subject or the like. Can be. In this case, only the method of dividing the ranging area shown in FIG. 7 is different.

Alternatively, a plurality of ranging areas to be used may be grouped and grouped together, or the ranging area to be used may be selected so as to draw a certain pattern according to a shooting mode.

Further, as the moving speed detecting method, a method other than that described in each of the above embodiments may be used. For example, a time change of the image shift amount detected in step S43 of FIG. 15 may be calculated.

As described above, according to the multi-point automatic focusing camera of the present invention, when a moving object is photographed by a camera having a plurality of distance measuring points, the moving object is focused on the front end thereof, so that the moving object is focused. A photograph that is not focused at an odd position can be obtained.

Although the above embodiments have been described, the present invention includes the following inventions.

(1) A plurality of distance measuring areas are arranged in a shooting screen, and a multi-point automatic focus camera having a function of detecting a focus of a subject moving in the shooting screen is detected from each ranging area. From the distribution change due to the output value accompanying the time change, based on the image movement speed obtained by the image movement calculation unit, which detects the movement speed and the movement direction of the subject moving in the shooting screen, A focus detection area that determines a moving object of a subject and selects a focus detection area for which a maximum image movement speed is calculated while the image movement speed is less than a maximum limit value at which the image movement cannot be performed if the movement is not a moving object. And a selection unit.

(2) In the above multi-point automatic focusing camera,
The ranging area selection unit further determines whether the image moving speed of the moving object is within a range between a maximum limit value and a minimum limit value at which focusing is not possible, and proceeds to the camera if the range is within the range. In the moving direction, the distance measuring area indicating the maximum speed is selected as the focus position, and when the moving direction is far from the camera, the distance measuring area indicating the minimum speed is selected as the focus position. ).

[0165]

As described above in detail, according to the present invention, a plurality of distance measurement areas (focus detection areas) are arranged in a photographing screen, and when a moving subject is brought into focus, movement is required for approaching movement. Focuses on the fastest ranging area, focuses on the slowest moving area for moving away from the camera, focuses on the tip of the moving subject, and does not focus on a halfway position Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a conceptual block configuration in a focus detection function of a multipoint autofocus camera of the present invention.

FIG. 2 is a diagram showing a cross section of a configuration example applied to a single-lens reflex camera as a multipoint autofocus camera according to the present invention.

FIG. 3 is a diagram schematically showing an optical system including a distance measurement.

FIG. 4 is a diagram showing functional blocks including an electric control system of the camera described in FIG. 2;

5 is a diagram showing a specific circuit configuration of the area sensor shown in FIG.

FIG. 6 is a diagram showing a specific circuit configuration of a pixel unit of the area sensor.

FIG. 7 is a diagram showing an example of the arrangement of each distance measurement area forming a detection area in a shooting screen.

FIG. 8 is a time chart for explaining an accumulation operation of the area sensor.

FIG. 9 is a diagram illustrating an example of an arrangement of distance measurement areas forming two area sensors.

FIG. 10 is a diagram linearly showing an array of photodiodes corresponding to an area.

FIG. 11 is a flowchart for explaining based on a processing procedure relating to an image shift amount detection routine.

FIG. 12 is a diagram for explaining the principle of focus detection for a moving subject.

FIG. 13 is a diagram for explaining movement of a subject image.

FIG. 14 is a flowchart illustrating a movement amount detection routine.

FIG. 15 is a flowchart illustrating an AF detection routine.

FIG. 16 is a diagram for explaining a shift for detecting a moving amount of a subject image in the first embodiment.

FIG. 17 is a diagram illustrating, as an example, a scene in which a train approaches a curve as a composition of a captured image.

FIG. 18 is a flowchart for explaining a main routine of a camera to which the multipoint autofocus camera of the present invention is applied.

FIG. 19 is a flowchart for describing selection of a distance measurement area when a subject is a moving object in the first embodiment.

FIG. 20 is a diagram illustrating a speed distribution and a change in the speed distribution of all the distance measurement areas arranged on the photographing screen according to the second embodiment.

FIG. 21 is a flowchart for describing selection of a distance measurement area when a subject is a moving object in the second embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 focus detection unit (area sensor) 2 focus calculation unit 3 image movement amount calculation unit 4 ranging area selection unit 5 focus control unit 6 focus adjustment unit

Claims (3)

[Claims] 1. A multi-point automatic focus camera having a plurality of focus detection areas, wherein: an image movement calculation means for calculating an amount relating to movement of a subject image in each focus detection area; A first selection unit for preferentially selecting the focus detection area in which image movement is fast. 2. A multi-point auto-focus camera having a plurality of focus detection areas, an image movement calculation means for calculating an amount of movement of a subject image in each focus detection area, and a calculation result of the image movement calculation means. A distribution output unit that outputs an amount related to the moving speed distribution of the plurality of focus detection regions; and a focus detection region corresponding to a tip end of the moving subject is determined based on an output of the distribution output unit and is preferentially determined. And a second selecting means for selecting. 3. The image processing apparatus according to claim 2, further comprising a moving direction determining unit configured to determine a moving direction of the subject, wherein the second selecting unit is configured to calculate the moving direction of the subject when the subject is approaching. When the focus detection area in which the image movement is fast is preferentially selected, and when the subject is far away, the focus detection area in which the image movement is slowest calculated by the image movement calculation means is preferentially selected. 3. The multi-point autofocus camera according to claim 2, wherein: