JP2002228916A - Range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a range finder which can correctly determine an object distance even if an additional object of high luminance besides an object image is present like a back light scene. SOLUTION: It is judged whether or not a noise signal component made incident from other than an object image is superposed in the picture signal of the object image detected from a sensor array, and a ranging method is then selected. Triangular ranging is performed when there is the reliability of a passive AF. When unreliable, active ranging using an IRED(infrared- emitting diode) or a stroboscope is performed according to object luminance, and then pulsed light is projected on the object to detect the object distance by regularly removing an image signal based on incident signal light in the sensor array.

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 in an autofocus (AF) camera and the like, and more particularly to a distance measuring apparatus which can correctly measure a distance even when light brighter than a subject image such as a backlight scene is mixed. It relates to a distance device.

[0002]

2. Description of the Related Art Generally, AF technology mounted on a camera can be roughly classified into two types: a passive type using a subject image, and an active type using a distance measuring light projected from the camera. Two ranging methods are known.
Each of these methods has a drawback based on the principle of the method, and a hybrid method or a combination method that compensates for the drawbacks by combining these two methods has been proposed.

[0003] Generally, two light paths obtained from two light paths having parallax are used.
In a so-called passive AF in which a subject distance is obtained based on a relative position of two image signals or the like, it is necessary to accurately detect a subject image. Specifically, two light paths are formed by two light receiving lenses provided, respectively, and light passing through those light paths is respectively received by a sensor array serving as a light receiving element, and an electric image signal is formed by photoelectric conversion. Generated. In this image signal, light from other than the subject image is also superimposed and generated. In the passive AF, if light from a subject other than the subject image in the distance measurement range (light receiving range) is mixed, the obtained distance measurement data is not limited to the distance measurement data for the main subject, and the surrounding rough subject (main (The subject other than the subject), and the distance measurement was not accurate.

On the other hand, the applicant of the present invention has proposed, for example, in Japanese Patent Application Laid-Open No. Hei 10-122855, a method of correcting a light component other than the above-mentioned subject to realize accurate distance measurement.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No.
Even if the Japanese Patent Application Laid-Open No. 122855 is used, for example, in a composition in which strong sunlight is directly incident on the lens of the distance measuring device as in a backlight scene, the amount of light to be superimposed is larger than the amount of light to the subject image. Likely to be. In such a case, the main subject image is relatively weakened due to the relationship of the dynamic range of the circuit, so that a sufficient effect cannot be expected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a distance measuring apparatus which can correctly obtain a subject distance even when a high-luminance miscellaneous subject exists in addition to a subject image such as a backlight scene.

[0007]

To achieve the above object, the present invention provides a sensor array for monitoring a subject image and outputting an image signal, and a noise signal component incident on the image signal from a portion other than the subject portion. Judgment means for judging that they are superimposed, projection means for projecting pulsed light to the object according to the judgment result of the judgment means, and removal of an image signal based on signal light constantly entering the sensor array And an extracting means for extracting a signal corresponding to the pulse light, wherein the extracting means is operated to provide a distance measuring apparatus for detecting the subject distance using the extracted signal.

The sensor array has a photocurrent integrating means, and the determining means determines the superposition of the noise signal component according to the contrast of the image signal and the amount of integration of the integrating means. Alternatively, the sensor array includes a noise signal component detection pixel and compares the output of the noise component detection pixel with the output of the sensor array to determine the superposition of the noise signal component.

Further, a first sensor array for monitoring a subject image and outputting an image signal, and a judging means for judging that a noise signal component incident from other than the subject portion is superimposed on the image signal. A distance measuring device for detecting the subject distance by activating a second sensor array adjacent to the first sensor array in accordance with a determination result of the determination means.

The distance measuring apparatus having the above-described configuration determines whether or not a noise signal component incident from other than the object image is superimposed on the image signal of the object image detected from the sensor array, and measures the distance. Select the method, perform the triangulation with the image signal if the passive AF is reliable, and if not,
By performing active distance measurement using pulse light such as an IRED or a strobe according to the luminance of the subject, an image signal component based on the signal light that is constantly incident on the sensor array is removed from the image signal of the subject, thereby reducing the subject distance. To detect.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention utilizes the stationary light removal function of the active AF, which removes the flare light component when the flare light detected by the passive AF, such as a backlight scene, is not good. First, the concept of stationary light removal according to the present invention will be described with reference to FIG.

In the configuration of the stationary light removing circuit, the light receiving element 21 is grounded via the current path (source / drain) of the transistor 22. The gate of the transistor 22 is connected to a holding capacitor 23 whose other end is grounded.
Is connected to the current detection circuit 24 via one of the two. Further, the current detection circuit 24 is connected to the negative input terminal (-) of the integration amplifier 26 via the switch 25, and the power supply voltage is applied to the positive input terminal (+). In addition, the integrating amplifier 26
, An integrating capacitor 27 and a reset SW 28 are connected in parallel between the output terminal and the negative input terminal. The output terminal of the integrating amplifier 26 is connected to the positive input terminal (+) of the comparator 29.
, And a predetermined level Vc serving as a reference is applied to the negative input terminal (-). Further, an infrared light emitting diode 9 and a condenser lens 8 are provided.

In such a configuration, for example, in accordance with the amount of incident light corresponding to one pixel constituting a sensor array for detecting an image signal in the light receiving element 21, the photocurrent Ip output therefrom is controlled by a steady light removing transistor. 22 to the ground (GND), and to an integrating circuit including an integrating amplifier 26, an integrating capacitor 27, a reset SW 28, and the like.
The current detection circuit 24 controls the gate voltage of the transistor 22 so that no current flows.

The gate voltage of the transistor 22 is fixed by the potential stored in the holding capacitor 23. In this state, for example, an infrared light emitting diode (IRE)
D) When the light 9 is emitted, the light for distance measurement is pulse-projected to the subject through the condenser lens 8 and the current detection circuit 24 is deactivated, the capacitor 23 prevents sudden changes in the pulse light. Can not respond to the voltage change at both ends. If the switch 25 is turned on (conducting) at this time, only the photocurrent corresponding to the pulsed light is input to the integration circuit, and the integration amplifier 26
Outputs a photoelectric conversion voltage based on the pulse light for distance measurement. If this output is subjected to A / D conversion, the steady light is removed, that is, the reflected light amount data corresponding to the reflected signal light can be detected.

When outputting a signal in accordance with the brightness of the image of the object without projecting the distance measuring light, the stationary light removing circuit is deactivated and the photocurrent of the sensor is directly input to the integrating circuit. If the integration is performed for a predetermined time, an integrated output corresponding to the brightness of the image is generated. If the integrated output is subjected to A / D conversion under the control of the CPU, an image signal can be obtained. Such a distance measuring mode for projecting the distance measuring light is generally used when the image is dark, and in a bright scene, the distance measuring light need not be projected.

At this time, the brightness is determined by the current detection circuit 24.
Is turned off, and as shown in FIG. 2B, after the reset SW 28 is once turned on, a steady light current Ip is supplied to the integration amplifier 26, and a waiting time until the integration voltage reaches the predetermined level Vc. During tINT, detection is performed using the comparator 29. Here, the waiting time tINT is short in a bright scene, and the waiting time tINT is long in a dark scene. Brightness / darkness can be determined only by counting the waiting time tINT. However, at this time, the light emitting diode 9 is kept inactive.

FIG. 1 shows an example of the configuration of a distance measuring device mounted on a camera according to a first embodiment of the present invention. This distance measuring device includes an arithmetic control unit (CPU) 1 composed of a one-chip microcomputer or the like for performing arithmetic processing relating to distance measurement and controlling each component, and two distance measuring devices for forming an image of a subject 4. The lenses 2a and 2b, the sensor arrays 3a and 3b in which light receiving element pixels for receiving the formed subject image and generating an image signal by photoelectric conversion are arranged, and the above-described stationary light removing circuit 7, respectively. A / D conversion circuit 16 for converting an image signal from which stationary light has been removed into a digital signal
An integration determination circuit 7 that takes in the image signal from which the stationary light has been removed and performs integration determination described below, and an IRED 9 that projects ranging light used for active AF through a projection lens.
A driver unit 10 for controlling light emission of the IRED 9 and a strobe light emitting unit 1 for projecting strobe light as auxiliary light at the time of photographing
1, a strobe unit 12 for controlling strobe light emission, and a focusing unit 21 for focusing a photographic lens (not shown).

The arithmetic and control unit 1 has a pattern determining unit 14 for determining whether or not the subject images detected from the two sensor arrays 3a and 3b are the same, and a correlation for use in determining reliability. A correlation calculating unit 15 for performing calculations, a light amount determining unit 16 that projects distance measuring light when stationary light is removed, determines the amount of incident light reflected and incident on the subject, and a light amount determining unit 16
A comparison constant unit 19 for giving a comparison constant used for light amount determination according to an instruction from the control unit 18, a memory 20 such as an EEPROM for storing the comparison constant, a release switch 13, and a reliability for determining the reliability of distance measurement. Sex determination unit 17
And a control unit 18 that performs various controls on reliability.

In such a configuration, the distance measuring lens 2
a and 2b are arranged at a distance of a focal length f of a light receiving lens to form a subject image on the light receiving surfaces of the sensor arrays 3a and 3b, and are arranged with a parallax b between the light receiving lenses; The subject distance L can be obtained using the principle of distance measurement. Depending on the length of the subject distance L, the relative positions of the subject images formed on the two sensor arrays 3a and 3b with respect to the optical axis of each lens are changed.

In order to detect the change in the relative position, A
The / D converter 6 converts an integrated output obtained by processing the image signal obtained from the sensor array into a digital signal, and converts the digital image signals of the two sensor arrays in the arithmetic control unit 1 including a one-chip microcomputer or the like. In comparison, relative position difference detection and distance calculation are performed. Also, the pattern determination circuit 1
4 checks whether the images detected from the two sensor arrays are of the same subject, that is, whether the image pattern is appropriate for distance measurement. The reliability determination unit 17 determines the reliability of the distance measurement when it is a low contrast, a repetitive pattern, a monotonically increasing, or a monotonically decreasing pattern based on the matching degree of the image when the relative position difference is detected and the pattern determination result of the image. Judge as low.

Then, the arithmetic and control unit 1 determines the control amount of the focusing unit 21 by further adding the result of determination of the incident light amount by the light amount determination unit 16 to the results of these functions. Also, the input state of the release switch 13 is detected,
In addition, according to the camera photographing sequence, as necessary for distance measurement, etc., the light emission of the IRED 9 is controlled via the driver unit 10, and the strobe light emitting unit 1 is controlled via the strobe unit 12.
1 is controlled.

Next, with reference to FIGS. 3A to 3G, a description will be given of distance measurement in the present embodiment. FIG.
As shown in (a), in a shooting scene in which sunlight or the like is irradiated from the distance measuring lens 2a, light is scattered by the distance measuring lens 2a, and its flare component enters the sensor 3a. 4 cannot sufficiently be detected. That is, as shown in FIG. 3B, the relationship of the dynamic range by the integration circuit and the like as shown in FIG.
If the amount of flare components is large and the amount of light due to the image of the subject is relatively small, sufficient image contrast cannot be obtained, and correct distance measurement becomes impossible.

Therefore, as shown in FIG. 3D, most of the light incident on the sensor array as shown in FIG. 3C becomes a flare component and has low contrast as an image signal. All the light incident on the sensor array 3a is
It is removed by the stationary light removal circuit 5, and in this case,
Active AF, which measures distance by projecting pulse signal light, has higher accuracy. A mask for pattern formation may be provided in front of the lens for distance measurement, or a pattern of the light emitting unit itself may be used. In the former case, an obtained image signal is as shown in FIG. become.

When the amount of reflected signal light from the IRED 9 is small, the distance measurement is performed by projecting a strobe light with a larger amount of light. However, in this case, there is no specific pattern in the reflected signal light.
As shown in (f), the signal light distribution is flat and has low contrast. However, when monitoring the subject and the background, the signal light distribution has a peak as shown in FIG.

FIG. 8A shows an example in which the positional relationship between the sensor array 3a and the projection pattern is applied to a camera.
An example based on a camera screen is shown. This screen 31
A monitor area 32 is arranged at the center of the screen of the sensor array 3. In this case, the exposure must be controlled by irradiating the entire screen with the strobe light, and a wide pattern 34 is required.

However, if the composition is as shown in FIG. 8 (b), the reflected light 4a from the person 4 is reflected by the monitor area 32 of the sensor.
However, since the reflected lights 4b and 4c do not return from the background, they do not enter the monitor 32, and an image signal having only one peak as shown in FIG. 3 (g) is obtained. on the other hand,
Since the light 33 having a plurality of peaks is projected in a predetermined area by the IRED 9 as shown in FIG.
The reflected light distribution as shown in FIG.

In such a distance measuring device, the IRED 9
A mode in which distance measurement is performed based on a relative position difference between image signals of a target object without projecting light for distance measurement using a method such as the passive AF mode is called a passive AF mode. As described above, the accuracy deteriorates remarkably due to the mixing of the flare light.

A ranging mode that involves an operation of removing light such as an IRED or a strobe with a stationary light removing operation is referred to as an active AF mode. Although it is inferior, it is possible to perform distance measurement with the above-mentioned flare removed, and the effect is higher than that of passive AF even in a dark place.

With reference to the flowchart shown in FIG. 4, the distance measuring operation by the distance measuring device will be described. First, distance measurement in the passive AF mode is performed (step S1). For this, an integration time tINT when the image signal is integrated to a predetermined level is obtained (step S2). Then, it is determined whether or not the passive AF is reliable based on the above-described pattern determination or the result of the correlation operation (Step S).
3) If the reliability is high (YES), the distance is calculated by triangulation from the two image signal positions (step S2).
0), return. On the other hand, if the reliability is low (N
O), pre-ranging using the IRED 9 is performed (step S)
4). At this time, pulse light for a predetermined time is emitted n times, and A / A
An integrated voltage VINT is obtained by the D conversion circuit 6. If the integrated voltage VINT is large, it can be determined that the light of the IRED 9 has sufficiently arrived. However, if the integrated voltage VINT is small, the amount of light of the IRED 9 is insufficient, and more powerful strobe light projection is performed. At this time, as described above, a correct determination cannot be made unless a steady light component such as sunlight illuminating the subject or artificial lighting is considered.

Therefore, in order to detect the stationary light component, the integration time t obtained by the passive AF in step S2 is used.
The brightness is determined using the result of the INT. This determination is made by comparing the predetermined time t0 and the integration time tINT with the determination voltages V1 and V for determining the magnitude of the integrated voltage VINT at the time of pre-integration by the IRED 9 obtained in the preceding stage.
Determine 2. That is, it is determined that tINT> t0 (step S5), and when it is determined that the integration time tINT is shorter than the predetermined time t0 (NO) and “bright”, the determination voltage V2 and the integration voltage VINT are higher than the determination voltage V1. Are compared (VINT> V2) (step S6). This comparison is for determining whether to perform the distance measurement using the IRED 9 or the strobe light emitting unit 11.
Further, as the integrated voltage VINT, a voltage of the sensor having the largest incident light amount may be selected from among all the sensors constituting the sensor array, or a voltage having the largest incident light amount among the predetermined areas of the sensor array may be selected. You may choose. The same applies to step S10 described later.

In this comparison, if VINT> V2 (YES), the flow shifts to step S11 described later.
However, if VINT> V2 is not satisfied (VINT ≦ V2) (NO), strobe AF is performed (step S7), and it is determined whether or not integration is completed (step S8). If completed (YES), light amount determination P is performed (step S14).
This light amount determination also takes into account the number of times by a sensor at a predetermined position. On the other hand, if the integration has not been completed yet (NO), it is determined whether the integration has been performed up to a predetermined number of integrations n2 (step S9). If the predetermined number of integrations has not been reached (NO), the process returns to step S7, and the flash AF is repeatedly performed. On the other hand, if the predetermined number of integrations has been reached (YES), the flow proceeds to step S14.

Also, in the determination in step S5,
When the integration time tINT is longer than the predetermined time t0 in a dark scene and the integration time tINT is longer than the predetermined time t0 (YES), and it is determined to be “dark”, the determination voltage V1 smaller than the determination voltage V2 is compared with the integration voltage VINT (VINT> V1) (Step S10). This comparison is for determining whether to perform the distance measurement using the IRED 9 or the strobe light emitting unit 11. In this comparison, the integration voltage VIN
If T is greater than the determination voltage V1 (YES), IRE
IREDAF is performed by light emission of D9 (step S1).
1).

Next, it is determined whether or not the integration is completed (step S12). If completed (YES), step S14
Then, the light amount determination P is performed. On the other hand, if the integration has not been completed yet (NO), it is determined whether the integration has been performed up to a predetermined number of integrations n1 (step S13). If the number has not reached the predetermined number of integrations (NO), the process returns to step S11 to repeatedly execute IREDAF. On the other hand, if the predetermined number of integrations has been reached (YES), the flow proceeds to step S14.

With the light source thus determined, in steps S11 and S7, the distance measurement in the active mode using the light of the IRED or the strobe as the distance measurement A is performed. This is a process in which light emission integration is repeated until a predetermined voltage is reached with light emission for a predetermined time. In the case of the IRED, control is performed in a loop of steps S11, S12, and S13. Control is performed in a loop of S8 and S9. Further, if the light projection integration is performed a predetermined number of times or more, energy is wasted and a time lag is affected. Therefore, the integration number limiter is defined in steps S9 and S13.

Next, the above-described pattern determination is performed (step S15). Then, it is determined whether or not triangulation can be performed based on the result P (integrated voltage VINT divided by the number of integration times) obtained by integrating the amount of reflected light in step S14 and the result of this pattern determination (step S16). If it is determined that the reflected light image signal allows the triangulation (YES),
Triangulation is performed (step S18), and it is determined whether or not the obtained result is reliable (step S19). If there is reliability (YES), the process returns.

If there is no reliability (NO), and if it is determined in step S16 that triangulation cannot be performed (NO), light amount AF using the reflected light amount P is performed (step S17). . This is a distance measurement method that utilizes the fact that when projecting light and examining the amount of reflected light, a large amount of light is returned from a short distance object and a small amount of light is returned from a long distance object. This is an effective distance measurement method for the subject. However, it is assumed that the reflectance of the subject falls within a predetermined range.

The distance measurement sequence described above is represented by timing charts as shown in FIGS. In the example shown in FIG. 5, in the IREDAF, light is projected three times by the IRED9, and the obtained pre-ranging results (VI when n0 = 3) are obtained.
Since NT) is the determination voltage V1, it is determined that distance measurement cannot be performed using the light of the IRED 9, and the example shifts to distance measurement using strobe light. In the strobe AF, the light emission is performed five times, and the light emission ends because the light reaches the integral determination voltage Vc.

In the example shown in FIG. 6, three IREDs
Even when the same integration amount is integrated in the light emission, when the integration time tINT in the passive AF is longer than the predetermined time to, "dark" and when it is shorter than the predetermined time t0, "light".
This shows a state in which the actual distance measurement A performed in the latter half of the sequence is switched to the IRED 9 or the strobe light emitting unit 11 when the determination voltage is switched to either V2 or the determination voltage V1.

In a "bright time", the photocurrent Ip increases, and noise is liable to be superimposed on the sensor and the hold transistor, and this is integrated and prevented from being integrated more than actually. If such processing is not performed, even in a scene where distance measurement by the IRED 9 cannot be actually performed,
IREDAF is selected, and erroneous distance measurement is performed in the actual distance measurement.
Even in such a case, by applying the present embodiment,
The distance measurement method is correctly selected, the mode is switched to the strobe AF, and accurate distance measurement with a sufficient amount of reflected light becomes possible.
Also, when unnecessary, IREDs with lower power consumption
Since the distance measurement is performed, the energy consumption of the power supply can be reduced.

Next, with reference to a flowchart shown in FIG. 7, a description will be given of a distance measuring operation for preventing erroneous distance measurement due to a noise error such as high luminance in the actual distance measurement.

First, the integration time tINT at the time of passive distance measurement
In order to select the value of the correction coefficient K of the light amount AF, the predetermined time t0 <the determination time t1, and tINT <t
It is determined whether the integration time tINT is shorter than a predetermined time t0 (YE) (step S30).
S), it is determined that the scene is very bright, and the correction coefficient K
= 1/4 (step S32). On the other hand, the integration time t
If INT is longer than the predetermined time t0 (NO), it is determined that the scene is a dark scene, and then it is determined whether or not tINT <t1 (step S31).
If T is longer than the determination time t1 (NO), it is determined that the scene is a dark scene, and the correction coefficient K = 1 (step S3).
3). On the other hand, if the integration time tINT is shorter than the determination time t1 (YES), it is determined that the scene has an intermediate brightness, and the correction coefficient K is set to 1/2 (step S3).
4).

These judgments are branched into a very bright scene, a dark scene, and a scene of intermediate brightness. In the correction coefficient K, in a dark scene, it is not necessary to consider a noise error. Therefore, the correction coefficient K is "1". However, as the brightness increases, the correction coefficient K is reduced to "1/2" and "1/4". . Then, using the determined correction coefficient K, 1 / x
= K√ (P / n) / P0 to calculate the distance (step S35).

This is to prevent noise and offset components from being integrated in a bright scene to easily produce an output on the short distance side. In the AF camera, the reciprocal 1/2 of the object distance proportional to the amount of focusing lens extraction is used. When calculating
Light amount P reflected from a 1 m subject in one light emission integration
By multiplying the above-described correction coefficient K by an equation using 0, the number of times of light emission n, and the amount of incident light P, the light amount A of the bright object is obtained.
The error of F can be reduced.

In the present embodiment, accurate distance detection is possible even in the case of backlight by using the active AF mode that can correctly measure the distance even in such a bright scene. For that purpose, it is necessary to accurately determine whether or not the passive AF is reliable in the step S3 shown in FIG. 4 indicating that the distance measurement by the passive AF is difficult.

The state in which the reliability of the passive AF is low is when measuring the distance of a dark scene or a subject having no contrast. The former can be determined by the length of the integration time tINT.
Further, the magnitude of the contrast is determined by the maximum value and the minimum value of the obtained image signal.

The flare detection method will be described with reference to the flowchart shown in FIG. This flowchart corresponds to the sequence of step S3 in FIG. 4 described above.

First, a difference ΔSD between the maximum value and the minimum value of the integration amount of the image signal in a predetermined area of the sensor array is detected (step S41). Next, assuming that there is a relationship of t0 << t1, the integration time tINT obtained in step S2 shown in FIG. 4 is compared with a determination value t1 (step S42).
If the integration time tINT is longer than the determination value t1, (YE
S) In the above-described dark scene, as a situation where passive AF is weak, “passive N” is not suitable for passive AF.
J is determined ”(step S46). On the other hand, if the integration time tINT is shorter than the determination value t1 (NO), it is determined that the scene is a dark scene, and the integration time tINT is set to the predetermined value t0.
And (Step S43).

In this comparison, if the integration time tINT is shorter than the predetermined value t0 (YES), it corresponds to the luminance at which flare is considered to occur in a bright scene, and whether the contrast ΔSD is lower than the predetermined value ΔSDφ. Is determined (step S44). Here, ΔSD is a predetermined value ΔSDφ
If it is determined that it is lower (YES), it is determined that a flare has occurred, and the process proceeds to step S46. On the other hand, if ΔSD is higher than the predetermined value ΔSDφ (NO), it is determined that the passive AF is reliable and “passive OK”, and distance measurement is performed in the passive AF mode (step S47).

In step S43, if the integration time tINT is longer than the predetermined value t0 (NO), it is determined whether or not the contrast ΔSD is lower than the predetermined value ΔSD1 (step S45). Here, ΔSD is a predetermined value ΔS
If it is higher than D1 (NO), the process proceeds to step S47, and if it is lower, the process proceeds to step S46. When the process branches from step S43 to step S45, the predetermined value Δ
The contrast is determined by comparing with SD1.
> ΔSD1, and these are obtained in step S47 even if the contrast is relatively small.
It determines "passive OK" and performs distance measurement in the passive mode.

That is, when the integration time tINT is short,
The contrast determination level is strict, flare determination is performed, and more advantageous active-type distance measurement is performed. According to the present embodiment, it is possible to provide a ranging device capable of performing a correct ranging even if a flare occurs at the time of backlight.

Next, FIG. 10 shows and describes the concept of a distance measuring device mounted on a camera according to a second embodiment of the present invention. In this embodiment, as shown in FIGS. 10A and 10B, above and below the sensor arrays 3a and 3b,
The sensor arrays 41a, 41b, 42a, and 42a are provided side by side, and sunlight directly shines on the light receiving lens, and the light receiving lens 2
In a situation where the entire light glows, utilizing the fact that intense light is incident on all these sensors, the integration time of these sensors is compared by the comparison unit 43, and when both are completed in a short time, Determine the occurrence of flare. FIG. 10B shows the relationship between the sensor and the light receiving lenses 2a and 2b when the sensor is viewed from the front.

The flare detection method will be described with reference to the flowchart shown in FIG. This flowchart corresponds to the sequence of step S3 in FIG. 4 described above.

As in the sequence of FIG. 9 described above, first, the brightness is determined from the integration time tINT obtained in step S2 of FIG. 4 (steps S51 and S52). In this determination, if the integration time tINT is shorter than the determination value t1, (Y
ES), it is determined that the scene is dark, and the passive AF
Is determined to be unsuitable “passive NG” (step S5
9) Execute active AF. On the other hand, the integration time t
If INT is longer than the determination value t1 (NO), the integration time tINT is compared with a predetermined value t0 (step S52).
In this comparison, if the integration time tINT is shorter than the determination value t0 (YES), it is determined that the scene is a bright scene, and the adjacent sensor 41a monitors the integration time tINT41 (step S53).
Monitor the integration time tINT42 (step S5).
4). Subsequently, it is determined whether or not these integration times tINT41 are the same as the integration times tINT of the sensor array 3a (step S55).
S), assuming that a flare has occurred, and step S59
"Passive NG" is not suitable for passive AF
And return. On the other hand, if not the same (N
O), it is determined whether or not the integration time tINT42 is the same as the integration time tINT of the sensor array 3a (step S56). If the integration time tINT42 is the same (YES), as shown in FIG. It is determined that the image signal from the chest may not be affected by the backlight, and it is determined whether or not the contrast of the adjacent sensor 41a is OK (step S5).
7). Here, if the contrast of the image of this part is determined and it is OK (YES), the image data of the adjacent sensor arrays 41a and 41b is adopted instead of the image signals of the sensor arrays 3a and 3b (step S58). The calculation is switched to the distance calculation using the image data. With this control, distance measurement with an image signal that is least affected by backlight can be performed. Then, return. But OK
If not (NO), the process moves to step S59.

In the comparison in step S52, if the integration time tINT is longer than the determination value t0 (NO),
In step S56, if the integration time tINT42 is not the same as the integration time tINT of the sensor array 3a (NO), it is determined whether or not the contrast is OK (step S60). If it is not OK (NO), the process proceeds to step S57.

As described above, according to the present embodiment, an active AF is employed when a plurality of sensor arrays are provided, and when the flare is large, and if the sensor is partially unaffected by flare, the sensor is used. By adopting the output, the distance measurement at the time of backlight was made more accurate.

[0056]

As described in detail above, according to the present invention, it is possible to improve the distance measurement accuracy of a scene where it was difficult to measure the distance by the passive AF in the past. A distance measuring device capable of distance and focusing can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a distance measuring device mounted on a camera according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining the concept of stationary light removal according to the present invention.

FIG. 3 is a diagram for explaining distance measurement according to the first embodiment.

FIG. 4 is a flowchart illustrating a distance measuring operation performed by the distance measuring device according to the first embodiment.

FIG. 5 is a timing chart for explaining a distance measuring sequence.

FIG. 6 is a timing chart for explaining a distance measuring sequence.

FIG. 7 is a flowchart for explaining a distance measurement operation in which erroneous distance measurement due to a noise error such as high luminance in the actual distance measurement is prevented.

FIG. 8 is a diagram illustrating an example for describing an example in which a positional relationship between a sensor array and a light projection pattern is applied to a camera.

FIG. 9 is a timing chart for explaining a flare detection method.

FIG. 10 is a diagram illustrating a concept of a distance measuring device mounted on a camera according to a second embodiment.

FIG. 11 is a flowchart for explaining a distance measuring operation by the distance measuring device according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Operation control part (CPU) 2a, 2b ... Distance measuring lens 3a, 3b ... Sensor array 4 ... Subject 5 ... Steady-state light removal circuit 6 ... A / D conversion circuit 7 ... Integral judgment circuit 8 ... Condensing lens 9 ... IRED 10 ... Driver unit 11 ... Strobe light emitting unit 12 ... Strobe unit 13 ... Release switch 14 ... Pattern judgment unit control unit 15 ... Correlation calculation unit 1 16 ... Light amount judgment unit 17 ... Reliability judgment unit 18 ... Control unit 19 ... Comparison constant Unit 20: Memory 21: Focusing unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F112 AC03 AC06 BA07 CA02 DA04 EA05 FA07 FA21 FA29 FA33 FA38 FA45 2H011 AA01 BA05 BB02 BB04 CA28 DA01 DA08 2H051 BB07 BB10 CB20 CB24 CB29 CC02 CC12 CE08

Claims (4)

[Claims] A sensor array for monitoring a subject image and outputting an image signal; a determining unit for determining that a noise signal component incident from a portion other than the subject portion is superimposed on the image signal; Projecting means for projecting pulsed light on the subject in accordance with the determination result, and extracting means for removing an image signal based on signal light constantly incident on the sensor array and extracting a signal corresponding to the pulsed light; A distance measuring device comprising: operating the extracting means; and detecting the subject distance using the extracted signal. 2. The sensor array according to claim 1, wherein said sensor array has a photocurrent integration means, and said determination means determines the superposition of said noise signal component according to a contrast of said image signal and an integration amount of said integration means. The distance measuring device according to claim 1, wherein 3. The sensor array further includes a noise signal component detection pixel, and compares the output of the noise component detection pixel with the output of the sensor array to determine the superposition of the noise signal component. The distance measuring apparatus according to claim 1, wherein: 4. A first sensor array for monitoring a subject image and outputting an image signal, and determining means for determining that a noise signal component incident from other than the subject portion is superimposed on the image signal. A distance measuring device for detecting the subject distance by activating a second sensor array adjacent to the first sensor array in accordance with a result of the determination by the determination means.