JP2001154087A - Range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a range finder for obtaining a difference signal between a pair of image signals using a normal light removing means, and then deciding a range finding area based on this. SOLUTION: This range finder is provided with photodetecting elements 4a and 4b for separately photodetecting a pair of field images formed by an optical system having parallax, and then outputting a pair of field signals, a light projecting source 14 for projecting range finding pulse light to plural range finding areas, normal light removing parts 17a and 17b for detecting normal light component of one of the pair of field image signals when the light source 14 is actuated, and then removing the normal light component of the other field image signal so as to select the active/non-active state of a function of removing the normal light component from the output of the photodetecting means, SW1 to SW4 for switching the operative/inoperative state of the normal light removing parts 17a and 17b, and a photocurrent integration part 5 for setting a range finding area, based on the output signals of the normal light removing parts 17a and 17b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring apparatus used for an image pickup apparatus such as a silver halide camera, a digital camera, and a video camera. In connection with a distance measuring device that realizes multi-auto focus (hereinafter, referred to as multi-AF),
In particular, the present invention relates to a distance measuring device characterized by having a wide ranging area in multi AF such as full screen AF.

[0002]

2. Description of the Related Art At present, in an image pickup apparatus such as a camera, a multi-AF using a distance measuring apparatus has been generally used. Further, cameras equipped with a distance measuring device for measuring the object distance at three, five, or seven points in a photographing screen have been commercialized even at low-cost models.

The multi-AF is a one-dimensional multi-AF in which distance measurement areas are arranged on a straight line. Recently, signs of commercialization of a two-dimensional multi-AF and an area AF have been observed.

As an example, as shown in FIG. 22, for example, a camera equipped with a distance measuring device having an area AF function in which as many as 45 distance measuring areas 17 are provided for a finder field of view 16 has been commercialized. The fact is that it is also available on the market.

[0005] In such a multi-AF according to the prior art, in view of the fact that a complicated calculation such as a distance measurement operation must be repeatedly executed for the increased number of distance measurement areas,
Various inventions for improving such a time lag have been proposed.

For example, in Japanese Patent Application Laid-Open No. 2-158705, first, a plurality of subject distance information is acquired in a first ranging mode in which a plurality of locations of a subject are roughly measured without high accuracy, and the closest distance is obtained from the information. A technique is disclosed in which a subject showing an equivalent subject distance is selected, and only the selected subject is measured in the second distance measurement mode with high accuracy, thereby improving the time lag as described above. .

Further, Japanese Patent Application Laid-Open No. 63-131019 has a basic concept that, in an active AF, it is assumed that the closest main subject is present at a position where the amount of reflected light of a projected light beam is the largest. There is disclosed a technology for improving the time lag as described above by omitting distance measurement calculation for a portion having a small number.

[0008] However, the AF method according to the prior art employs an active method, so that a high effect can be obtained in measures against time lag.
When performing full-screen AF or the like, the gathering of light projecting elements and the gathering of light receiving elements cannot be avoided, and there is a high barrier to practical use.

On the other hand, in the case of the passive system, the miniaturization of the light receiving element has progressed far more than the miniaturization of the active type light emitting and receiving element. Since there is no such method, it can be said that the passive method is more convenient for wide-area multi-AF such as full-screen AF.

In view of the above, Japanese Patent Application Laid-Open No. 62-1036
In the gazette of No. 15, the correlation calculation is roughly performed on a plurality of ranging areas, and one ranging area is selected based on the result.
Performs high-precision correlation calculation only for this selected ranging area,
There is disclosed a technique characterized by improving a time lag under a passive method.

[0011] However, even if a rough correlation operation is performed,
For example, every other sensor data used in the calculation is used to thin out the sensor data, and the correlation calculation cannot be omitted. Therefore, it can be said that the efficiency of the countermeasure against the time lag is higher or equal in the active method than in the passive method.

[0012]

To implement a wide-area multi-AF such as a full-screen AF, measures against time lag are indispensable conditions. However, in the prior art, a distance measuring method and a time lag measure effective at present are provided. There is nothing.

Expensive C operating at high speed at the expense of cost
Only a countermeasure against time lag with a PU or microcomputer is taken.

Therefore, the conventional distance measuring apparatus has a problem that the measures against time lag are insufficient and the time lag is large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a highly accurate and inexpensive distance measuring apparatus which has a small time lag, is quick, has a high reliability of a distance measurement result, and has a high accuracy. Is to do. It is still another object of the present invention to provide a distance measuring device that can obtain a difference signal between a pair of image signals by using a stationary light removing unit and thereby determine a distance measuring area.

[0016]

In order to achieve the above object, according to a first aspect of the present invention, there is provided a distance measuring apparatus for a camera having a plurality of distance measuring areas inside an object scene, wherein a parallax is detected. Light receiving means for receiving a pair of field images formed by the optical system and outputting a pair of field signals, and projecting distance measuring pulse light toward the plurality of distance measuring areas. A light projecting means, and detecting the one steady light component of the pair of object image signals when the light projecting means is operated, thereby removing the other steady light component, thereby detecting the light receiving means. Stationary light removing means capable of selecting operation / non-operation of a function of removing a stationary light component from the output of the light source; integration mode setting means for switching the operation / non-operation of the stationary light removing means; Based on the output signal of the steady light removal means when the And a distance measurement area setting means for setting a distance measurement area, wherein the distance measurement calculation is performed based on the output of the light receiving means in the distance measurement area set by the distance measurement area setting means. A distance measuring device is provided.

In a second aspect, in the first aspect, the light receiving means includes a stationary light storage section for storing a stationary light level, and a stationary light level stored in the stationary light storage section, the difference being subtracted from the stationary light level. And a stationary light removing unit for removing a light component.

According to the first and second aspects, the following operations are provided.

That is, according to a first aspect of the present invention, there is provided a distance measuring apparatus for a camera having a plurality of distance measuring areas inside a field, and a pair of images formed by an optical system having parallax by light receiving means. Are respectively received, a pair of field signals are output, a distance measuring pulse light is projected toward the plurality of distance measuring areas by the light projecting means, and the distance measuring pulse light is projected by the stationary light removing means. One stationary light component of the pair of field image signals when the light means is operated is detected, whereby the other stationary light component is removed, and the steady light component is removed from the output of the light receiving means. The operation / non-operation of the function to be performed is selected, the integration mode setting means switches the operation / non-operation of the stationary light removing means, and the distance measuring area setting means activates the stationary light removing means. The output signal of the steady light removal means And Zui, setting ranging areas is performed, the ranging operation on the basis of the output of said light receiving means in a distance measuring area set by the ranging area setting means is performed.

According to a second aspect, in the first aspect, the stationary light level stored in the stationary light storage unit by the stationary light storage unit and the stationary light level stored in the stationary light storage unit by the stationary light removal unit in the light receiving means. Is subtracted, thereby removing the stationary light component.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

The present invention is characterized in that a difference signal between a pair of image signals is obtained by using a stationary light removing means, and a distance measuring area is determined based on the difference signal.

FIG. 1 is a diagram showing a configuration of a distance measuring apparatus according to a first embodiment of the present invention.

In the figure, at a predetermined position of the distance measuring device,
Light receiving lenses 1a and 1b for condensing the subject light and the auxiliary light reflected by the subject are provided.

Further, a housing 2 is provided to secure and divide the optical paths of the light receiving lenses 1a and 1b, and to prevent unnecessary outside light from entering the optical paths. For the above-mentioned purpose, the housing 2 is usually formed of a material having a good light-shielding property and a dark color such as black.

The casing 2 may be formed of the above-mentioned materials, may be provided with an oblique line inside the casing to prevent irregular reflection of light inside, or may be subjected to embossing. Needless to say, it is possible to adopt the one that has been done.

In the drawing, reference numeral 3 denotes an autofocus integrated circuit (hereinafter, referred to as AFIC). Hereinafter, the relevant A
The configuration of the FIC 3 will be described in detail.

Inside the AFIC 3, an aggregate of light receiving elements 4a and 4b for receiving the light condensed by the light receiving lenses 1a and 1b and performing photoelectric conversion is provided. Further, a photocurrent integration unit 5 for integrating the photocurrent photoelectrically converted by the light receiving elements 4a and 4b for each element is provided. Further, a reset section 7 for resetting each section inside the AFIC 3 is provided.

Reference numeral 8 in the figure designates an arbitrary area in the photocurrent integrator 5, detects the maximum integration amount of the photocurrent in the set area, and temporarily samples the maximum integration amount. A monitor signal detection range setting and monitor signal output unit for holding and outputting a monitor signal for controlling integration of a photocurrent.

In addition, the AFIC 3 has a storage unit 9 for storing and storing a plurality of integration amounts which are integration results of the photocurrent integration unit 5 and a monitor signal detection range setting and monitor signal output unit 8 and a storage unit 9. An output unit 10 for outputting contents to the outside is also provided.

The output unit 10 may of course have a built-in amplification means for amplifying a signal inside. It should be noted that, based on the external control signal, A
The control section 11 plays a role of controlling the inside of the FIC 3, and power is supplied to each section from a bias section 12 having a group of voltage sources, current sources, and the like.

On the other hand, a light projecting light source 14 for irradiating the subject with light and a light projecting lens 1c for condensing the light emitted from the light projecting light source 14 are also provided. This projection light source 14
The driving is controlled by the driver unit 15.

In the figure, reference numeral 13 denotes a central processing unit (hereinafter, referred to as a CPU). The CPU 13 corresponds to a central mechanism of the distance measuring apparatus according to the first embodiment that controls the above-described units. And, of course, the CPU 13 controls various operations of the camera other than the control of the distance measuring device. If the functions of the CPU 13 are limited to those related to a distance measuring device, the outline thereof mainly includes obtaining information on a subject and calculating distances. Note that the functions related to distance measurement, such as information acquisition of a subject and distance measurement calculation, do not necessarily belong to the CPU 13 and may be built in the AFIC 3.

In addition to the configuration described above, although not shown in the figure, EEP is a non-volatile memory for storing data necessary for distance measurement, for example, adjustment data.
It is also possible to incorporate a ROM or the like.

Hereinafter, referring to the flowchart of FIG.
The operation of the distance measuring apparatus according to the embodiment having the configuration shown in FIG. 1 will be described in detail. In the following description, the description will proceed with reference to the configuration of FIG.

First, the CPU 13 performs an initial setting of the distance measuring device (step S1).

That is, first, the CPU 13 itself performs a preparatory operation for starting distance measurement, and after the completion of the preparation, enters a distance measuring operation. When the CPU 13 sends a control signal to the control unit 11,
The control unit 11 activates the reset unit 7. With this activation, the reset unit 7 causes the photocurrent integrator 5, the monitor signal detection range setting and monitor signal output unit 8, and the storage unit 9 to
Reset each one.

Subsequently, the CPU 13 executes integration (step S2).

That is, the CPU 13 sends a signal for setting the monitor signal detection range to the control unit 11. Upon receiving this signal, the control unit 11 sets a monitor signal detection range. Next, the CPU 13 executes the driver unit 1 as necessary.
5, a signal for causing the light emitting unit 14 to emit light is sent,
The light emitting unit 14 emits light. Subsequently, the CPU 13
A signal for starting photocurrent integration is output to the control unit 11. Upon receiving this signal, the control unit 11 causes the photocurrent integration unit 5 to start photocurrent integration. Then, after executing the predetermined operation, the CPU 13 ends the integration of the photocurrent.

Next, sensor data (left / right) L (m)
And R (m) (step S3).

That is, after the completion of the integration, the CPU 13
The storage unit 9 stores all the integration amounts of the plurality of photoelectric conversion elements integrated by the photocurrent integration unit 5. This storage unit 9
Is the image signal of the subject. CPU
13 acquires this image signal via the output unit 10. C
The PU 13 obtains difference data of the acquired sensor data, and detects the maximum value of the difference data and the position of the maximum value on the sensor. At this time, the difference data is ΔLR (m) =
L (m) −R (m), and ΔLR (m) may be calculated by rounding to zero if it is an absolute value or a negative number.

Subsequently, the CPU 13 proceeds to step S3
A comparison is made between the maximum value detected in step (1) and the predetermined value (step S4). Here, when the maximum value is larger than the predetermined value,
It is determined that this is the case where the main subject is estimated to be at a finite distance, and the process proceeds to step S5 described later. on the other hand,
If the maximum value is smaller than the predetermined value, it is determined that the main subject is distant and the main subject position cannot be estimated, and the process proceeds to step S6.

In step S5, the CPU 13 sets a distance measurement area in a predetermined area centered on the point of the maximum value. That is, in the scene shown in FIG. 3, sensor data is obtained by integration (see FIGS. 4A and 4B), and the distance measurement area is determined based on the difference data (see FIG. 4C) and its maximum value. The distance is set (see FIGS. 4A and 4B), and the subject distance is obtained from the integration result and the set distance measurement area.
Note that the distance measurement area may be detected or set.

In step S6, a distance measurement area is set in a predetermined area (default position) prepared in advance. For example, in the scene shown in FIG. 5, the difference data (FIG. 6C)
) Cannot estimate the required subject position. In this case, the distance measurement area may be set at the default position. That is, as shown in FIGS. 6A and 6B, the distance measurement areas may be overlapped, or a plurality of distance measurement areas may be set without overlapping.

Subsequently, the CPU 13 executes the correlation calculation and the closest selection (step S8).

That is, when the integration is completed, the CPU 13 causes the storage unit 9 to store the integration amount of each photoelectric conversion element, which is the image signal of the subject. Subsequently, the output unit 10 outputs and acquires an image signal of the subject. At this time, the CPU 13
May acquire all the image signals of the subject, but it is more efficient to acquire an image signal of only the ranging area set in step S5 or S6.

The CPU 13 performs a correlation operation for each distance measurement area based on the acquired image signal of the object, and obtains a phase difference of the object image for each distance measurement area. Such a phase difference corresponds to the distance of the subject. Then, the closest distance is selected from a plurality of object distances obtained from a plurality of distance measurement areas, and the closest object distance is set as a final distance measurement result.

After the above processing, the CPU 13
A post-processing including an operation of turning off the power of the power supply 3 is executed, and a series of distance measurement operations is completed (step S9).

Here, as described above, the operation executed by the CPU 13 may of course be executed under the control of the AFIC 3.

For example, when a very wide range is measured by a one-dimensional or two-dimensional sensor as in the above-described prior art, the number of distance measurement areas to be set is very large, and a complicated calculation such as a correlation operation is required. Operations must be repeated very many times, resulting in a large time lag or a high-speed and expensive C
Use of a PU increases costs.

On the other hand, according to the embodiment of the present invention, the position of the main subject is estimated by acquiring the subject image obtained by integrating the subject image and the maximum value of the sensor data and the difference data thereof. It becomes possible.

Therefore, in this embodiment, the minimum distance measurement area necessary for detecting the estimated distance of the main subject with high accuracy can be set, so that there is no need to perform unnecessary calculations. That is, the high-speed and expensive CPU 13
Is unnecessary, and the effect that the time lag does not increase significantly is exhibited.

As described above, the configuration, operation, and operation of the embodiment of the present invention
The effects were outlined.

Next, the distance measuring operation of the distance measuring apparatus according to the embodiment will be described with reference to the flowchart of FIG. In the following description, the description will be made with reference to various flowcharts and figures relating to the shooting scene and sensor data of the integration at that time, as appropriate.

First, the CPU 13 performs an initial setting of the distance measuring device (step S11).

This step S11 is the same processing as step S1 in FIG. 2 described above. The CPU 13 itself, the photocurrent integrator 5, the monitor signal detection range setting and the reset operation of the monitor signal output unit 8 and the storage unit 9 are performed. .

Subsequently, the CPU 13 performs pre-integration 1 (step S12).

Although the pre-integration was not performed in FIG. 2, it is performed here in order to determine some of the integration conditions of the main integration in advance. Although not shown, there is a means for setting / switching the sensor sensitivity of the photoelectric conversion element, and sets the sensor sensitivity to high sensitivity. For the sensor sensitivity switching, a method of switching the amplification rate of the photocurrent, switching the capacity of the integration capacity, or the like can be adopted. The light source 14 is turned off and integrates light from the subject. In the integral control, the integral operation is performed only for a predetermined short time.

Next, the CPU 13 detects the maximum integration amount of the pre-integration (step S13). This is related to the brightness of the brightest part of the subject, and is used to determine the sensor sensitivity in the main integration and the presence / absence of auxiliary light. For detection of the maximum integration amount, a monitor signal may be output after the integration is completed, and this may be used as the maximum integration amount.

Subsequently, the CPU 13 determines a part of the integration conditions for the main integration (step S14). The main conditions are the setting of the sensor sensitivity and the presence or absence of the auxiliary light.

Next, the CPU 13 executes the main integration 1 (step S15).

This is the same as the integration in step S2 in the flowchart of FIG. 2 described above. Then, CPU
In step S16, the difference between the left sensor data and the right sensor data is obtained, and the maximum value of the difference signal and the position on the sensor are detected. Here, it is estimated that the main subject exists at the position of the maximum difference signal. The maximum difference signal is the difference between the image signals of the reflected light from the subject, that is, the larger the difference signal is in the phase difference, the larger the phase difference is, and the higher the possibility that the subject is closest to the subject is. It is highly possible.

Here, the main subject search in steps S15 and S16 in FIG. 7 will be described in more detail with reference to the flowchart in FIG.

First, the CPU 13 determines whether the AF mode of the camera is a normal mode or a spot mode (step S31). Here, the "spot mode" is an AF mode in which distance measurement is performed only for the center of the screen. In the spot mode, the main subject search is returned without performing any operation.

On the other hand, when the mode is not the spot mode, FIG.
As in step S15, the main integration 1 is executed (step S32). Subsequently, the CPU 13 acquires the sensor data of the main integration 1, that is, the image signal of the subject from the AFIC 3 (step S33).

Then, the CPU 13 proceeds to step S3
The maximum value of the difference signal between the left and right image signals acquired in step 3 is searched, and only those having a maximum value within a predetermined range (Pmax to Pmin) are extracted (step S34).

For example, when a mannequin or the like in a show window is a subject as in the scene shown in FIG. 9 and there is a bright spot due to the reflection of sunlight on the glass, integration is performed as shown in FIG.
Image signals as shown in FIGS. 0 (a) and (b) are obtained. Then, when the local maximum value is searched for in the difference signal between the left and right image signals (see FIG. 10C), three local maximum values are extracted. The respective maximum values are, in order from the left, an image signal of the right mannequin, an image signal of the opposite direction of the glass, and an image signal of the left mannequin.

From these local maxima, FIG.
As shown in (b), values within a predetermined range (Pmax to Pmax)
By extracting only the image of min), it is possible to exclude the image signal due to the opposite of the glass, and it is possible to prevent the estimation of the main subject from being erroneous.

Returning to the description of FIG. 8, in the subsequent step S35, the CPU 13 sets the flag f− indicating that no valid maximum value was detected from the difference signal between the left and right image signals of the integration.
Set searcherr to 1. This flag "f-
“searcherr” is set to 0 when a valid maximum value remains.

Subsequently, the CPU 13 determines whether there is an effective maximum value (step S36), and returns if there is no effective maximum value, and executes the next step 39 if there is an effective maximum value. In step S39, a value whose calculation result is 0 is excluded by adding a correction function to the local maximum value.

Here, the correction function is a function of the position on the sensor, the focal length of the photographing optical system of the camera, and the photographing screen mode of the camera (standard, panorama, high-vision).
An example is shown in FIG. Hereinafter, the meaning of the correction function will be described.

First, the photographing view angle (range) of the camera is determined by the focal length of the photographing optical system of the camera and the input information of the photographing screen mode of the camera. The existence probability of the main subject at each position with respect to the shooting angle of view of the camera is an example of the correction function. Note that FIG. 3 shows the shooting angle of view corresponding to the focal length for each shooting type.

As shown in FIG. 13, the existence probability of the main subject at the center of the screen is high, and the existence probability becomes lower toward the periphery, and the existence probability becomes almost zero near the outer periphery of the screen. When the angle of view of the camera and the position on the sensor are associated with each other, it is possible to extract or exclude the weight of the local maximum value by adding the correction function to the local maximum value.

For example, the case of the scene shown in FIG. 11 will be described.

In the case where a main subject exists near the center and a rough subject exists at the left and right ends as in the scene of FIG. 11, when integration is performed, the difference signal between the left and right image signals is as shown in FIG. become. The difference signal is a difference signal due to a rough subject on the left side of the screen, a difference signal due to a main subject, and a difference signal due to a rough subject on the right side of the screen in order from the left maximum value.

By the way, there are three local maximum values of the difference signal of the integral. When the above-mentioned correction function is added to this, that is, for example, when the local maximum value is multiplied by the correction function, the local maximum value existing on the outer peripheral portion of the screen is calculated. It is possible to exclude, and it is possible to exclude surrounding rough subjects.

Here, the description returns to FIG. After the above processing, the CPU 13 determines again whether or not there is an effective maximum value (step S40), returns if there is no effective maximum value, and if there is such an effective maximum value, at least one effective value at this time. Since the maximum value remains, the flag f-search
err is set to 0 (step S41).

When the flag “f-searchcherr” is 0, it means that an effective maximum value has been found. Subsequently, the CPU 13 further narrows the maximum value, and determines a predetermined range (Pmax) including the maximum maximum value (Pmax) among the remaining maximum values.
The maximum values other than max to Pmax-Po) are excluded (step S42).

In the scene of FIG. 9 described above, there are two mannequins, and the clothes worn are white and black.
As described above, the subject has a color, and the difference in color causes a difference in reflectance. When estimating the closest main subject, the reflectance of the subject cannot be ignored. In this embodiment, erroneous distance measurement due to an erroneous estimation of the main subject position caused by the reflectance of the subject is prevented by treating the maximum values included in the range of Po equally.

By executing steps S32 to S42 as described above, the right and left of the integration including at least the maximum value of the main subject is not affected by the specular reflection of the glass, the peripheral rough subject, and the reflectance of the subject. It is possible to extract the maximum value of the difference signal of the image signal.

Next, the CPU 13 determines whether or not the number of remaining effective maxima is larger or smaller than a predetermined number areamax (step S43). If it is larger, the local maxima are further narrowed down, and the maximum maxima are increased from the area max. (Step S44).

In steps S43 and S44, one of the objects of the present invention is to set a minimum necessary distance measurement area and measure the distance, thereby realizing multi-AF over a wide area without increasing the time lag. On the contrary, this is a process executed in order to prevent the distance measurement area from being set more than necessary.

Steps S43 and S43 in FIG.
44 corresponds to a function of limiting the number of distance measurement areas. Subsequently, the limitation on the number of distance measurement areas will be described in more detail with reference to the flowchart in FIG.

First, the upper limit ar of the number of settable distance measuring areas ar
eamax = k0 (step S50). This is a case where the mode of the camera is the auto (normal) mode, and k0 is a default value.

Subsequently, it is determined whether the AF mode of the camera is the spot mode (step S51). If the AF mode is the spot mode, areamax = 1 or k1 is set (step S52). If the AF mode is not the spot mode, the next step S5 is performed.
Execute 3.

Next, it is determined whether or not the AF mode of the camera is the moving body mode (step S53). If the AF mode is the moving body mode, areamax = 1 or k2 is set (step S5).
4) If not in the moving object mode, the next step S55 is executed.

Subsequently, it is determined whether or not the AF mode of the camera is the remote control mode (step S55). In the case of the remote control mode, areamax is set to k3 (step S5).
6) If not in the remote control mode, execute the next step S57.

Next, it is determined whether or not the AF mode of the camera is the self mode (step S57). In the case of the self mode, areamax = k4 is set (step S58).
If not in the self mode, the next step S59 is executed.

The magnitude relation of the above constants is as follows.

1 ≦ k1 ≦ k2 <k0 <k3 ≦ k4 (1) In this embodiment, in the spot mode meaning that the ranging area is limited to the center or in the operation mode in which a large time lag is not allowed, the ranging area is set to In remote control mode, self mode, and the like, in which a large time lag is allowed, the aim is to increase the distance measurement area.

Subsequently, the magnitude relation between the number of effective maxima and areamax is compared (step S59). If the number of effective maxima is large, the number of effective maxima is reduced to areamax (step S60). As an example of how to reduce the effective maximum value, the maximum value may be areamax from the largest value. If the correction function is not taken into account, the value may be taken into account.
Of course, it is also possible to extract reamax pieces.

As described above, the main subject search and the limitation of the number of distance measurement areas have been described with reference to the flowcharts of FIGS. 8 and 14 and the other drawings except for the flowchart of FIG. That is, the information necessary for setting the necessary minimum number of distance measurement areas including at least the main subject has been obtained.

Next, step S in the flowchart of FIG.
The processing after 17 will be described. Step S17 in FIG.
In step S16, the magnitude relationship between the maximum difference signal and the predetermined value is determined in step S16.
This means that the presence or absence of an effective maximum value is determined according to the content at a detailed level such as 4.

If the maximum difference signal is larger than a predetermined value or has an effective maximum value, a distance measurement area is set based on the point of the maximum difference signal or the point of the effective maximum value (step S18). On the contrary,
If the maximum difference signal is equal to or less than a predetermined value or there is no effective maximum value, a ranging area is set in a previously prepared region (default region) (step S1).
9).

Steps S17 to S19 are a distance measuring area setting function.

Hereinafter, the distance measuring area setting function will be described in more detail with reference to the flowchart of FIG.

First, the CPU 13 executes the f-search
The value of rr is determined (step S61). Here, f
If −searcherr = 0, it is determined that the effective maximum value is present, that is, the main subject position can be estimated.
When archerr = 1, it is determined that there is no effective maximum value, that is, the main subject position cannot be estimated. Next, the camera A
It is determined whether or not the F mode is the spot mode (step S62).

Normally, a distance measurement area is set (step S63). That is, one or more distance measurement areas are set around the sensor address of the effective maximum value.

Then, the above-mentioned step S20 is repeated until there is no remaining effective maximum value for which no distance measurement area has been set.
2 is repeatedly executed to set a distance measurement area for each effective maximum value (step S64).

If the AF mode of the camera is the spot mode in step S62, a distance measuring area is set in a predetermined area (default area) prepared in advance (step S66). More specifically, one or more areas are set near the center on the sensor. In other words, the vicinity of the center on the sensor is also near the center of the photographing screen. When a plurality of areas are set, the areas may partially overlap or may not partially overlap.

When the main subject position cannot be estimated,
A distance measurement area is set (steps S65 and S66). In this step S66, as described above, a distance measurement area is set near the center of the shooting screen, and in step S65, a distance measurement area is set around the center. The number of areas to be set is one or more on both sides around the spot area. In the ranging area set in step S65, the areas may or may not partially overlap. Also,
The areas set in steps S65 and S66 may or may not partially overlap.

Here, in the situation of the scene shown in FIG. 11, there is a technique for photographing using the spot mode. In this case, the distance measurement area is set in a predetermined area regardless of the position of the main subject estimated as illustrated.

In the situation of the scene shown in FIG. 5, the position of the main subject cannot be estimated, and the distance measurement area is set in a predetermined area. At this time, one area at the center is
It is conceivable that step S65 sets the peripheral four areas at step S65, but step S66 sets the central three areas and step S65 sets the two peripheral areas. Many variations are conceivable.

As an example of this variation, FIG.
The above step S63 will be described in more detail with reference to the flowchart of FIG.

The concept of FIG. 16 is that three distance measurement areas are set for one effective local maximum value, and the three distance measurement areas are one of the one distance measurement area and the remaining two areas. It is intended to have a positional relationship that partially overlaps.

That is, first, the number of sensors in the area of the distance measuring area to be set is determined based on the maximum value, and stored (step S70). This is for the purpose of preventing the near-far mixture which is a weak subject of the passive AF. If the maximum value is small, the subject is far (however, this is not limited depending on the brightness of the subject), and the number of sensors in the area is reduced for a far subject. On the other hand, if the maximum value is large, the subject is closer (however, this is not a limitation depending on the brightness of the subject), and the number of sensors in the area is increased for a closer subject. Here, it cannot be ignored that the relationship between the maximum value of the difference signal and the subject distance depends on the subject luminance (contrast with the background), but the following measures may be taken. The difference signal may be obtained after normalizing the image signal (sensor data) of the subject for which the difference signal is to be obtained based on the maximum sensor data value. That is, only the phase difference information remains in the normalized difference signal of the sensor data without the contrast information. Therefore, it is possible to estimate the approximate subject distance from the maximum value of the difference signal of the normalized sensor data.

In order to determine the number of sensors in the area from the maximum value of the difference signal of the sensor data after the normalization, FIG.
The number of sensors in the area is determined with reference to a table as shown in FIG.

FIG. 18B is a diagram showing the difference signal between the left and right sensor data after the normalization. As shown,
The number of sensors in the ranging area is determined according to the maximum value, and the ranging area is set.

The phase difference of an image is larger for an image signal of a short-distance object, and is smaller for a long-distance object. In this regard, the present embodiment is advantageous because a wide ranging area is set for a short-distance subject and a narrow ranging area is set for a long-distance subject.

For example, in the scene shown in FIG. 18 (a), a person behind and a torii gate are mixed in perspective. However, there is no means for detecting mixed perspective in the image signal of the subject, and only the perspective of the subject can be estimated. Therefore, as shown in FIG. 19, when it is estimated that the subject is far,
If the distance measurement area is set to be narrow, it is possible to prevent erroneous distance measurement due to mixed distance as shown in the figure. As described above, the distance measurement area is set based on the normalized difference signal between the left and right sensor data, but the normalization method is supplemented. One cause of the sensor data having a high frequency includes a mixed perspective, and the scene in FIG. 18A also corresponds to this. The sensor data composed of the person behind and the torii will include high frequency components. In this case, the sensor data of the rear person and the torii gate may not be separately normalized, but may be collectively normalized. It is more efficient to normalize the high-frequency components collectively as a whole. The above is the description of step S70. Next, in step S71, 1 to the effective maximum value is set.
Set the second ranging area.

The start address of this distance measurement area is ((maximum sensor address) − (number of sensors in area)) / 2 (2). This distance measurement area is set by two, that is, the start address of the area and the number of sensors in the area.

Subsequently, in the setting of the second area, the start address is ((sensor address of local maximum value) − (number of sensors in area)) × 3/2 + (number of overlap sensors) (3) In step S403, a third area is set. The start address is ((local maximum sensor address) + (number of sensors in area)) / 2− (number of overlap sensors) (4). In order to set the first and third areas, a new constant called the number of overlap sensors is also required (steps S72 and S73).

Returning to the description of FIG. 16, step S7
In step S5, it is determined whether or not the effective maximum value remains. If there is no remaining value, the routine returns.
Decrement amax. Then, if areamax is not 0 in step S77, since the effective maximum value remains without fail, the process returns to step S70 at the head and continues to set the distance measurement area. If areamax is 0, the routine returns.

With the above processing, the integration and the processing are completed. Since all the conditions necessary for the distance measurement calculation and the like are completed, the correlation calculation is finally performed.

Returning to the flowchart of FIG. 7, the description will be continued from step S22.

In step S22, a correlation operation is performed for each of the distance measurement areas, and subject distance information for each of the distance measurement areas is calculated. Further, a closest selection is performed to select the closest one of the obtained subject distance information. When selecting the closest,
In the embodiment, a function of determining the reliability of the subject distance information and excluding low reliability information from selection candidates in advance is used (not shown). The reliability determination is a known means, and the simplest determination is a determination based on contrast, and other various determinations are known, and one or a plurality of determinations are used.

At the time of the above-described closest selection, it is determined whether effective subject distance information cannot be selected only with subject information having low reliability, that is, whether or not distance measurement is impossible (step S23). Here, when effective subject distance information is obtained, the process proceeds to step S28. On the other hand, when the distance measurement is impossible and the main integration 1 is the auxiliary light is turned off, the main integration 2 is executed (step S24).

Subsequently, step S27 is a light amount distance measurement, which is known in active type AF. Subject distance information is calculated based on the result of the main integration 1 or the main integration 2 in step S15 or S24, particularly, the maximum integration amount. Here, the maximum integration amount is conceptually a reflected light amount of light emitted from the auxiliary light (light projection light source 14) by the closest subject.

In this way, post-processing such as stopping the power supply to the AFIC 3 of the distance measuring device is executed, and the distance measurement is completed (step S28).

Next, a second embodiment will be described.

The outline of the first embodiment is that light from a subject is received by a light receiving means, and the distance is measured based on the obtained image signal of the subject. Further, a distance measurement area is set based on the difference signal between the image signal of the subject or the normalized difference signal of the image signal of the subject, and then the distance measurement is performed only on the set distance measurement area.

In contrast to the first embodiment,
The outline of the second embodiment is as follows. In the first embodiment, the detection of the difference signal is performed by software. On the other hand, in the second embodiment, the detection of the difference signal is performed by hardware. It is assumed that. Hereinafter, the second embodiment will be described in detail with reference to the drawings.

First, FIG. 20 will be described.
1 is substantially the same as that of FIG. 1, except that a difference calculation unit 15 and a switch SW are added. Hereinafter, the description of the same configuration as that of FIG. 1 will be omitted, and the description will focus on the operation of the difference calculation unit 15 and the switch SW.

In the following, the image signal of the subject is stored and stored in the storage unit 9. Then, the image signal of the subject passes through the output unit 10 and the difference calculation unit 15
Is output to. The switch SW is connected to the difference calculation unit 15 side, and outputs the difference signal of the image signal of the subject to the CPU.
13 is output. CP that obtained the difference signal of the image signal of the subject
U13 determines the distance measurement area of the subject based on this.

On the basis of this determination, the CPU 13
A control signal is sent to the control unit 11 of C3 so as to output an image signal of a subject in a predetermined range. The switch SW is connected to the output unit 10
The predetermined range of the image signal of the subject, which is selected and connected to the side and stored and stored in the storage unit 9, is output to the CPU 13. When the CPU 13 acquires an image signal of the subject corresponding to the subject's ranging area, the CPU 13 executes a ranging calculation such as a correlation calculation and ends the ranging. The details are the same as in the first embodiment, and a description thereof will be omitted.

Next, a third embodiment will be described.

In the third embodiment, similarly to the second embodiment, a difference signal of a subject image is obtained by hardware. FIG. 21 shows only the part for obtaining the difference signal. Hereinafter, the description will proceed with reference to FIG.

First, the outline of the sensor will be described. The stationary light storage units 16a and 16b and the stationary light removing unit 17 corresponding to each of the light receiving elements 4a and 4b for each pixel of the light receiving element.
a and 17b are added. The operation will be described below.

In FIG. 21, when the switch SW1 is selected on the left side and the switch SW2 is selected on the right side, it functions as a sensor used in a conventionally known passive AF system. Next, when the switches SW1 and SW2 are selected on the opposite side to the above, and the switch SW3 is selected on the left side and the switch SW4 is selected on the right side, the sensor removes the steady light from the luminance information of the subject, that is, the auxiliary light 14 Is turned on, only the reflected light of the auxiliary light 14 is detected. In other words, it functions in the same manner as the signal detection of the active AF method.

As described above, the sensor shown in FIG. 21 performs a passive operation and an active operation, and is therefore referred to as a hybrid AF sensor.
No. 6921 is disclosed.

Next, a method for detecting a difference signal between subject image signals, which is the essence of the present embodiment, will be described. In FIG. 21, switches SW1 and SW3 are selected on the right side, and switches SW2 and SW4 are selected on the left side. When the subject image is integrated in this state (the auxiliary light 14 is turned off), the light receiving element 4
In a and 4b, since the stationary light is removed by the subject luminance information from the other light receiving element, integration is performed by the difference between the luminance information. That is, a difference signal between the subject image signals is detected.
After the detection of the difference signal, the same operation as in the first embodiment is executed.

The embodiments of the present invention have been described above.
The present invention is not limited to this, and various modifications and changes are possible. For example, if the photocurrent integration method is different,
The word “maximum value” in the above description may change to a minimum value, or the brightness of the image signal may be reversed, and the present invention is not limited to the above embodiment.

In the above embodiment, according to the viewpoint,
It can also be interpreted that the photoelectric conversion element is a one-dimensional line sensor. However, the present invention is not limited to the line sensor, and may be a two-dimensional area sensor or an area sensor including a two-dimensional discretely distributed line sensor or the like. In any case, in processing the image signal, it is natural to perform one-dimensional decomposition and processing, and it does not depend on whether the sensor is one-dimensional or two-dimensional. does not change.

As described above, according to the present invention, when performing a wide-area multi-AF such as a full-screen AF, for example, the position where the main subject exists is estimated in advance by a countermeasure against time lag, and the minimum necessary It measures only the subject distance at the position, but it is possible to accurately estimate the position where the main subject exists without being affected by the reflectance of the subject with respect to the projected light beam, and it is highly reliable and highly accurate Can be realized and supplied without increasing the cost.

The above embodiment of the present invention includes the following inventions.

That is, light receiving means for receiving subject light from a plurality of distance measurement areas by a pair of integrating sensors and outputting a pair of subject image signals, and pulse light for distance measurement toward the plurality of distance measurement areas. The light receiving means by detecting one stationary light component of the pair of subject image signals when the light emitting means is operated, and thereby removing the other stationary light component. A stationary light removing unit capable of selecting operation / non-operation of a function of removing a stationary light component from an output of the unit, an integration mode setting unit for switching operation / non-operation of the stationary light removing unit, and a stationary light removing unit A distance measuring area setting means for setting a distance measuring area based on an output signal of the stationary light removing means when the means is operated, and in a distance measuring area set by the distance measuring area setting means. Of the above light receiving means Distance measuring apparatus being characterized in that to perform the distance calculation based on the force.

[0137]

As described in detail above, according to the present invention,
It is possible to provide a highly accurate and inexpensive distance measuring apparatus which has a small time lag, is quick, has high reliability of a distance measurement result, and has high accuracy. Further, it is possible to provide a distance measuring apparatus which measures a difference in time lag by obtaining a difference signal between a pair of image signals using the stationary light removing means and determining a distance measuring area based on the signal.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating an operation of the distance measuring apparatus according to the embodiment in detail.

FIG. 3 is a diagram illustrating an example of a shooting scene.

FIG. 4 is a diagram showing sensor data, its difference data, and a distance measurement area corresponding to the shooting scene of FIG. 3;

FIG. 5 is a diagram illustrating an example of a shooting scene.

6 is a diagram showing sensor data corresponding to the shooting scene of FIG. 5, its difference data, and a distance measurement area.

FIG. 7 is a flowchart related to a distance measuring operation of the distance measuring apparatus according to the embodiment.

FIG. 8 is a flowchart illustrating the main subject search in steps S15 and S16 of FIG. 7 in further detail.

FIG. 9 is a diagram illustrating an example of a shooting scene.

FIG. 10 shows sensor data corresponding to the shooting scene shown in FIG. 9;
It is a figure which shows the difference data and a ranging area.

FIG. 11 is a diagram illustrating an example of a shooting scene.

12 is a diagram showing sensor data corresponding to the shooting scene in FIG. 11, its difference data, and a distance measurement area.

FIG. 13 is a diagram for describing a correction function.

FIG. 14 is a flowchart for explaining in more detail the limitation on the number of distance measurement areas according to steps S43 and S44 in FIG. 8;

FIG. 15 is a flowchart for explaining in more detail the ranging area setting function according to steps S17 to S19 of FIG. 7;

FIG. 16 is a flowchart illustrating the operation of step S63 in FIG. 15 in further detail.

FIG. 17 is a diagram showing an example of a table for determining the number of sensors in an area.

FIG. 18 is a diagram illustrating an example of a shooting scene and an image signal obtained by pre-integration in an active mode.

19 is a diagram illustrating sensor data and a distance measurement area corresponding to the shooting scene in FIG. 18;

FIG. 20 is a block diagram illustrating a configuration of a distance measuring apparatus according to a second embodiment.

FIG. 21 is a block diagram illustrating a configuration of a distance measuring apparatus according to a third embodiment.

FIG. 22 is a view showing a finder field of view of a distance measuring apparatus according to the related art.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light receiving lens 2 housing 3 AFIC 4 light receiving element 5 photocurrent integrating unit 6 steady light removing unit 7 reset unit 8 monitor signal detection range setting and monitor signal output unit 9 storage unit 10 output unit 11 control unit 12 bias unit 13 CPU 14 Projection light source 15 Driver section 16 Viewfinder field of view 17 Distance measurement area 18 Difference calculation section

Continued on front page F-term (reference) 2F065 AA06 DD06 DD12 EE00 FF01 FF05 FF09 FF12 FF21 GG08 HH02 JJ02 JJ03 JJ05 JJ25 JJ26 QQ13 QQ14 QQ23 QQ25 QQ29 QQ31 QQ33 QQ36 2F112 AC06 BA05 FA07 FA01 FA04 DA08 2H051 BB07 BB10 CC02 CC12 CC17 CE06 CE08 CE16 DA03 DA07 GB12

Claims (2)

[Claims] 1. A distance measuring apparatus for a camera having a plurality of distance-measurable areas inside an object field, wherein each of the light receiving apparatuses receives a pair of object field images formed by an optical system having parallax. Light-receiving means for outputting a field-of-view signal; light-emitting means for projecting distance-measuring pulse light toward the plurality of distance-measuring areas; and the pair of objects when the light-emitting means is operated. A function of detecting one of the stationary light components in the image signal and removing the other stationary light component thereby to select the operation or non-operation of the function of removing the stationary light component from the output of the light receiving means. Removing means; integration mode setting means for switching between operation and non-operation of the stationary light removing means; and an output signal of the stationary light removing means when the stationary light removing means is activated. Distance measuring area setting means for performing setting. A distance measuring apparatus, wherein a distance calculation is performed based on an output of the light receiving means in a distance measuring area set by the distance measuring area setting means. 2. The method according to claim 1, wherein the light receiving unit includes a stationary light storage unit configured to store a stationary light level, a stationary light removing unit configured to remove the stationary light component by subtracting the stationary light level stored in the stationary light storage unit, The distance measuring apparatus according to claim 1, comprising: