JP2002244027A - Range-finding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a range-finding device realizing stable range-finding regardless of luminance and a distance. SOLUTION: First light for range-finding is projected to a subject 12 from an IRED 1, and second light for range-finding stronger than that of the IRED 1 is projected to the subject 12 from a strobe light emitting part 15. The distribution of incident light from the subject 12 is converted into an electrical signal by sensor arrays 3a and 3b. Then, a CPU 10 decides a distance to the subject 12 from output from the sensor arrays 3a and 3b in the case of projecting the first light for range-finding. It decides the distance to the subject 12 from the output from the sensor arrays 3a and 3b in the case of projecting the second light for range-finding. Whether range-finding is performed by the first light for range-finding or the second light for range-finding is selected based on the output level of the sensor arrays 3a and 3b in the case of not projecting the first and the second light for range-finding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device,
More specifically, the present invention relates to an improvement in a distance measuring device used for an autofocus (AF) camera or the like.

[0002]

2. Description of the Related Art The AF technology of a camera is 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.

However, each of these methods has a drawback based on the principle of the method. Therefore, for example, as disclosed in JP-A-63-49738 and the like,
Various AF methods combining both methods have been proposed as a hybrid method or a combination method.

[0004]

However, in the above-mentioned proposal combining the conventional passive AF system and the active AF system, a sufficient description has been given of, for example, an improvement to a scene in which the passive AF system and the active AF system are not good at. Had not been done.

For example, when the subject is a distant, low-contrast, and bright scene, the passive AF using an image has a low active contrast because the contrast is low.
In the F system, correct distance measurement is difficult because of the long distance. In other words, even with a hybrid AF camera, there were scenes in which correct focusing was difficult.

The present invention has been made in view of the above problems, and has as its object to provide a distance measuring apparatus capable of performing stable distance measurement regardless of luminance and distance.

[0007]

That is, a first aspect of the present invention provides a first light source for projecting a first distance measuring light to an object, and the first light source to the object. A second projection light source for projecting a second distance measurement light stronger than the distance measurement light, a sensor array for converting an incident light distribution from an object into an electric signal, and projecting the first distance measurement light First distance determining means for determining a distance to the object from the output of the sensor array at the time of performing the above operation, and a distance from the sensor array at the time of projecting the second distance measuring light to the object. Second distance determining means for determining a distance, and the first distance determining means or the second distance determining means based on an output level of the sensor array when the first and second distance measuring lights are not projected. And selecting means for selecting any of the distance determining means.

According to a second aspect of the present invention, there is provided a sensor array for converting a distribution of light incident from an object into an electric signal, a light source for projecting distance measuring light to the object, and a light source for the light source. A reflection signal light extraction means for extracting a reflection signal light at the time of projection from the sensor array output; a determination means for judging the sensor array output level when the projection light source is not operating; In the distance device, an image signal output by the sensor array when the extracting means is not operated,
Alternatively, the distance is determined in accordance with a reflected light amount signal according to a result of comparing the determination level switched by the output of the determination means with the sensor array output level when the projection light source and the extraction means are operated.

In the distance measuring apparatus according to the present invention, a first light source for measuring distance is projected from a first light source to the object, and the first light for measuring distance is projected onto the object. Strong second distance measuring light is projected from the second projection light source. The distribution of incident light from the object is converted into an electric signal by the sensor array.
Then, the first distance determining means determines the distance to the object from the output of the sensor array when the first light for distance measurement is projected. Further, in a second distance determining means, a distance to the object is determined from an output of the sensor array when the second light for distance measurement is projected. Then, based on the output level of the sensor array when the first and second distance measuring lights are not projected, one of the first distance determining means and the second distance determining means selects one of them. Selected by means.

In the distance measuring apparatus of the present invention, distance measuring light is projected from the projecting light source to the object, and the distribution of light incident from the object is converted into an electric signal by the sensor array. Further, the reflected signal light when the projection light source is projected is extracted from the sensor array output by the reflected signal light extracting means. The determination means determines the output level of the sensor array when the extraction means and the projection light source are not operated. Then, the image signal output by the sensor array when the extracting means is not operated or the determination level switched by the output of the determining means is compared with the output level of the sensor array when the light emitting source and the extracting means are operated. The distance is determined according to the reflected light amount signal according to the result.

This makes it possible to prevent errors in distance measurement determination and calculation due to an error when stationary light is removed, which is a specific operation in active AF.

[0012]

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

First, the function of removing steady light will be described with reference to FIG.

In FIG. 2, light emitted from an infrared light emitting diode (IRED) 1 as a light projecting means is applied to a subject (not shown) via a condenser lens 2. Then, light reflected from an object, not shown, is incident on the light receiving elements 3a ₁ via a not shown light receiving lens. The light receiving element 3a _1, for example corresponding to one pixel of the sensor array for the image signal detection.

In accordance with the amount of incident light, the photocurrent I _P output therefrom goes to ground (GND) via a stationary light removing transistor 4b constituting a stationary light removing circuit together with a current detecting circuit 4a and a holding capacitor 4c. Swept away.
On the other hand, the gate voltage of the transistor 4b is controlled by the current detection circuit 4a so that no current flows through the integration circuit 5 including the integration amplifier 5a, the integration capacitor 5b, the reset switch (SW) 5c, and the like.

The holding capacitor 4c is for fixing the gate potential. In this state, if, for example, the IRED 1 is caused to emit light and the distance measuring light is pulse-projected to the subject via the condenser lens 2 and the current detection circuit 4a is deactivated, the pulse light changes rapidly. Does not respond to a voltage change across the capacitor 4c.
Therefore, when the switch 5d is turned on, only the photocurrent corresponding to the pulse light is input to the integration circuit 5, and the output of the integration amplifier 5a outputs the photoelectric conversion voltage based on the pulse light for distance measurement. You. If this output is subjected to A / D conversion, reflected light amount data corresponding to only the reflected signal light component can be detected.

However, as the steady-state light current I _P increases in a bright scene, an error component erroneously input to the integration circuit increases due to the influence of thermal noise, shut noise, and the like. In addition, the circuit is easily affected by the offset error of the circuit.

Therefore, conventionally, it has been difficult to accurately detect the amount of reflected light in a bright scene.

In order to determine the brightness of the steady light, the current detection circuit 4a is deactivated and the reset switch 5c is once turned on as shown in FIG. _P is poured, the time t _INT until the integral voltage reaches a predetermined level V _c the comparator 6
The detection may be performed by using. In a bright scene, the time _tINT is short, and in a dark scene, _tINT is long. Therefore, the brightness can be determined only by counting the time _tINT . At this time, the IRED 1 is not operated.

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

In FIG. 1, a CPU 10 is an arithmetic and control means composed of a one-chip microcomputer or the like. The CPU 10 includes an integration judging unit 6 for judging an output signal from the integrating circuit 5 and an A / D converter 7
A driver 11 for driving the IRED1,
Strobe circuit 14 for driving strobe light emitting section 15
, Focusing unit 16 and EEPR as storage means
The OM 17 and the release switch 18 are connected.

The CPU 10 includes an arithmetic control unit 20 and
It has a pattern determination unit 21, a correlation calculation unit 22, a reliability determination unit 23, a light amount determination unit 24, and a comparison constant circuit 25.

The sensor arrays 3a and 3b have the above-described light receiving element pixels arranged side by side. Light reflected from the subject 12 is incident on the sensor arrays 3a and 3b via light receiving lenses 13a and 13b. In order to form an image of the subject 12 on the sensor arrays 3a and 3b, two light receiving lenses 13 are provided in front of each sensor array.
a and 13b are provided separated by a focal length f. The parallax B is given to these lenses, and the subject distance L is obtained based on the principle of triangulation.

Depending on the magnitude of the subject distance L, the image of the subject 12 formed on the two sensor arrays 3a and 3b changes the relative position with respect to each lens optical axis. In order to detect this, the A / D conversion unit 7 uses the sensor arrays 3a, 3b
(Here, the integration circuit 5 is included in each pixel of each of the sensor arrays 3a and 3b, and is omitted in FIG. 1), and is converted into a digital signal.

Then, the CPU 10 compares the digital image signals of these two sensor arrays 3a and 3b,
The relative position difference detection and the distance calculation are performed. In order to check whether or not the images detected from the two sensor arrays 3a and 3b are of the same object, the CPU 1 determines whether or not the pattern of the image is suitable for distance measurement, It has a function such as a correlation operation unit 22 for detecting a relative position difference between images.

The reliability judging section 23 judges the degree of coincidence of the image when the relative position difference is detected, the pattern judgment result of the image, the low contrast, the repetitive pattern, the monotone increase, and the monotone decrease pattern. Pattern determination unit 21
The reliability of the distance measurement is determined from the output of the correlation calculation unit 22. In addition, the light quantity determination unit 24 projects the light for distance measurement at the time of the removal of the steady light, and determines the amount of incident light reflected and incident on the subject 12. These determination results are supplied to the arithmetic and control unit 20.

Further, the comparison constant circuit 25 determines the light amount by the light amount determination unit 24 beforehand in the EEPROM 17.
Is a circuit for reading out and setting the comparison constant stored in.

The control amount of the focusing unit 16 is determined from the results of these functions in the CPU 10.

The CPU 10 has a release switch 1
8 to control the camera shooting sequence. Furthermore, at the time of distance measurement, if necessary,
The light emission control of the IRED 1 is controlled through the driver 11, and the light emission of the strobe light emitting unit 15 is controlled through the strobe circuit 14.

In the present invention, an image signal output from a predetermined area is obtained by a distance measuring sensor (sensor array) 3a arranged as shown in FIG. 4 (a) as shown in FIG. 4 (b). It has a low contrast, a repetitive pattern as shown in FIG.
If the pattern is a monotonic change pattern as shown in (d), and if the reliability of the result of the correlation operation is low, I
The RED 1 is projected, and the distance is measured by the pattern of the reflected signal light. FIG. 4E shows an output pattern corresponding to the light projection pattern when the IRED 1 is projected.

Further, a mask for forming a pattern may be provided in front of the condenser lens 2, or a pattern of the light emitting section itself may be used.

Further, when the signal light reflected by the IRED 1 is small, the distance measurement is performed by light projection using the strobe light emitting section 15 having a larger light amount. However, in this case,
Since there is no specific pattern in the reflected signal light, a signal light distribution with low contrast is often obtained as shown in FIG. However, if the subject exists only in the center of the screen, a contrast is generated as shown in FIG. 4G, and the distance can be measured by this image.

FIG. 5 shows the positional relationship between the sensor array and the projection pattern with reference to the screen of a camera to which the present invention is applied.

The monitor area 27 of the sensor array is the screen 2
6 and the exposure must be controlled by irradiating the entire screen with the strobe light, resulting in a wide pattern 28.
The pattern light of the IRED forms a light and dark pattern as represented by a pattern 29.

In such a distance measuring apparatus, a mode in which the distance is measured by the relative position difference of the image signal of the object without projecting the distance measuring light is referred to as passive AF. On the other hand, a ranging mode that involves the above-described steady light removal operation and that involves light projection such as an IRED or a strobe is referred to as active AF.

Next, referring to the flowchart of FIG.
The operation of the distance measuring apparatus according to the present embodiment will be described.

First, in step S1, the distance measurement in the above-described passive mode is performed. Next, in step S2, an integration time _tINT when the image signal is integrated to a predetermined level is obtained. Then, in step S3, the reliability of the passive AF is determined.

Here, if the reliability of the passive AF is high due to the above-described pattern determination or the result of the correlation operation, the flow shifts to step S4 to calculate the distance from the two image signal positions by triangulation. Is On the other hand, when the reliability of the passive AF is low, the process proceeds to step S5, and the pre-ranging using the IRED1 is performed. At this time,
The pulse light for a predetermined time is emitted n ₀ times, and the A / D converter 6
The integral voltage V _INT is obtained by the following.

If the integrated voltage V _INT is large, I
Although it can be determined that the light from the RED 1 has reached the subject 12, if the V _INT is small, it is determined that the amount of light of the IRED 1 is not sufficient, and a stronger strobe light is projected. However, at this time, as described above, unless the steady light component such as sunlight or artificial lighting illuminating the subject 12 is taken into consideration, a correct determination cannot be made.

Therefore, in order to detect the steady light component, the result (t _INT ) of the integration time monitor at the time of the passive AF in step S1 (see step S2) is used. A decision is made. That is, by comparing the integration time t _INT with the predetermined time t ₀ , the determination voltages V ₁ and V ₂ for determining the magnitude of the integration voltage V _INT during the IRED pre-integration in the step S4 are determined.

If it is determined in step S6 that the integration time t _INT is shorter than the predetermined time t ₀ , that is, it is determined that the light is bright, the process proceeds to step S11, where V _{1 is set.}
Greater determination voltage V ₂ and V _INT is compared. Thus, it is determined whether the distance measurement using the IRED 1 or the distance measurement using the strobe light emitting unit 15 is performed. As a result, if the integrated voltage V _INT is higher than the determination voltage V ₂ , the process proceeds to step S8, and if the integrated voltage V _INT is lower than the determination voltage V ₂ , the process proceeds to step S12.

In step S6, a dark scene
And the integration time t _INTIs a predetermined time t₀
If it is longer, the process proceeds to step S7. Soshi
In step S7, the determination voltage V_TwoSmaller
Voltage V₁And integrated voltage V during IRED pre-integration_INTAnd
Be compared. As a result, distance measurement by IRED1 is performed.
To determine whether or not to perform distance measurement with the flash emission unit 15.
It is. As a result, the integrated voltage V_INTIs the judgment voltage V₁Than
If the value of the integral voltage V_INT
Is the judgment voltage V₁If smaller than, proceed to step S12
I do.

As the integrated voltage V _INT , the integrated voltage of the sensor having the largest incident light amount may be selected from all the sensors constituting the sensor array, or the integrated voltage V _INT may be selected from the predetermined area of the sensor array. A larger one may be selected.

In step S8 or step S12, the distance measurement is performed in the active mode using the light of the IRED 1 or the strobe light emitting unit 15 in the step S8 or step S12 (main distance measurement). In this method, light emission integration is repeated until light emission reaches a predetermined voltage during light emission for a predetermined time.

That is, in the case of distance measurement by IRED1, distance measurement by IRED1 is performed in step S8. Next, it is determined in step S9 whether the integration is completed. If the integration is not completed, the number of integrations is compared in step S10. If the number of integrations has not reached the limiter n ₁ , the process proceeds to step S8, and the process proceeds to step S8.
The processes from 8 to S10 are repeated. Then, step S9
In integration end, or if the number of integrations in step S10 has reached n ₁ of the limiter, the process proceeds to step S15.

On the other hand, in the case of distance measurement by the strobe light emitting section 15, the distance measurement by the strobe light emitting section 15 is performed in step S12. Next, it is determined in step S13 whether the integration is completed. If the integration is not completed, in step S14,
The integration times are compared. Here, integration count has not reached the n ₂ of the limiter, the process of step S12~S14 proceeds to step S12 are repeated. Then, integration is completed in step S13, or step S14.
In the integral number if reached n ₂ of the limiter, the process proceeds to step S15.

Distance measurement by IRED1, strobe light emitting unit 1
In any case of the distance measurement by 5, if light integration is performed a predetermined number of times or more, energy is wasted and a time lag is affected. Therefore, as described above, step S1
At 0, S14, integration count limiter (n _1, n ₂₎ is provided.

In step S15, the result P (integrated voltage V _INT divided by the number of integrations) obtained by integrating the amount of reflected light is obtained. Next, a pattern determination is performed in step S16. Then, the above step S
From the results obtained in steps S15 and S16,
It is determined whether or not triangulation is possible.

Here, if the reflected light image signal allows triangulation, the process proceeds to step S18 to perform triangulation. Then, the reliability of the result of the triangulation is determined in step S19. As a result, when the reliability of the triangulation is high, the main ranging is completed.

On the other hand, if the reliability of the triangulation is low, or if it is determined in step S17 that the pattern is not sufficient (triangulation is NG), the process proceeds to step S17.
The process proceeds to 20, and the light amount AF based on the reflected light amount P is performed. This is a distance measurement method that utilizes the fact that when projecting light and examining the amount of reflected light, more light is returned from a short distance and less light is returned from a longer distance.
This is an effective distance measurement method even for a subject having no contrast. However, it is assumed that the reflectance of the subject falls within a predetermined range.

FIGS. 7 and 8 are timing charts of the IRED, the integration, and the strobe, which operate according to the above flow chart.

FIG. 7 shows that the pre-ranging result (V _INT when n ₀ = 3) obtained by causing the IRED 1 to emit light three times is V ₁ or less, and that it is determined that the distance cannot be measured with the light of the IRED ₁ , The operation of an example in which a shift to distance measurement by light is shown is shown.

That is, pre-ranging by the IRED 1 is performed (step S5). Here, during pre-distance measurement with the IRED 1 emitting three times, it is determined that the distance cannot be measured with the light of the IRED ₁ because the integrated voltage V _INT is equal to or less than V ₁ (steps S6 and S7). Therefore, strobe AF is performed by the strobe light emitting unit 15 (step S1).
2). In this case, the flash has finished the emission so reaches the integral determination voltage V _c at five emission (step S13, S14).

Alternatively, it is determined that the distance cannot be measured with the light of the IRED 1 even if the integrated voltage V _INT at the time of the pre-distance measurement with the IRED 1 emitting three times is equal to or less than V ₂ (steps S 6 and S 11). . As a result, strobe AF is performed by the strobe light emitting unit 15 (step S12).

FIG. 8A shows that the integration time t during the passive AF is obtained even when the same integration amount is integrated in three IRED emission times.
₅ is a timing chart when _INT is greater than a predetermined time t ₀ (dark).

That is, pre-ranging by the IRED 1 is performed (step S5). The distance measuring time t _INT at the time of pre-ranging with the IRED 1 emitting light three times is equal to a predetermined time t.
Greater than _0, the integral voltage V _INT is judged it exceeds the predetermined voltage V ₁ (step S6, S7). Therefore, I
AF by RED1 is performed (step S8). Thereafter, IRED1 has ended light emission so reaches the integral determination voltage V _c at six emission (step S9, S1
0).

FIG. 8B is a timing chart when the integration time t _INT during the passive AF is less than or equal to the predetermined time t ₀ (during light) even when the same integration amount is integrated in three IRED emission times. .

That is, pre-ranging by the IRED 1 is performed (step S5). Here, during pre-distance measurement with the IRED 1 emitting three times, it is determined that the distance cannot be measured with the light of the IRED 1 because the integrated voltage V _INT is equal to or less than V ₂ (steps S6 and S11). Therefore, strobe AF is performed by the strobe light emitting unit 15 (step S1).
2). In this case, the flash has finished the emission so reaches the integral determination voltage V _c at three emission (step S13, S14).

[0059] Thus, the timing charts of FIGS. 7 and 8, by the judgment voltage is changed V _2, V ₁ and switching, is present ranging second half shown in broken line in the flowchart of FIG. 6, Switching to IRED or strobe is shown correspondingly.

When bright, as described above, the photocurrent I _P
With such a measure, noise is likely to be superimposed on the sensor and the hold transistor due to an increase in the noise, and the noise is integrated and integrated more than actually. If such a measure is not taken, the IRED may be selected in a scene where the distance cannot be actually measured by the IRED, and the distance may be erroneously measured in the actual distance measurement.

Even in such a case, with the above-described device of the present invention, the distance is correctly switched to the strobe-based distance measurement, and accurate distance measurement with a sufficient amount of reflected light can be performed. Also, when unnecessary, IRED ranging with less power consumption is performed, so that there is also an energy dissipation effect.

Next, an operation for taking measures to prevent the noise error at the time of high luminance from affecting the distance measurement in the actual distance measurement will be described.

FIG. 9 is a flowchart for explaining the subroutine "light amount AF" of step S20 in the flowchart of FIG.

[0064] In step S31, S32, determination of when to switch the correction coefficient K of the light amount AF by integration time t _INT during passive range finding is performed. Here, the predetermined time t
_{If 0} <t ₁ , a very bright scene (t _INT
<T ₀ ) proceeds to step S33, in the case of a dark scene (t
To _INT ≧ t ₁₎ is the step S34, and if the brightness of the scene between them _{(t 0 ≦ t INT <t} 1) is to step S35, the process proceeds respectively.

Since it is not necessary to consider noise errors in a dark scene, the correction coefficient K in step S34 is "1". And as the scene gets brighter,
This correction coefficient K is reduced to “１ ／” or “１ ／”. That is, in the case of a bright scene in step S33, "1/4" is set as the correction coefficient. Similarly, in the dark scene of step S34, the correction coefficient is set to "1", and in the scene of brightness between the two, "1/2" is set to the correction coefficient.

Thereafter, the flow shifts to step S36, where a long distance is calculated by the following equation (1).

[0067]

(Equation 1)

This countermeasures that in a bright scene, noise and offset components are integrated and the output is likely to be on the short distance side. When calculating the reciprocal 1 / L of the subject distance proportional to the extension amount of the focusing lens by the AF camera, the light quantity P ₀ reflected from the 1 m subject in one light emission integration, the number of times of light emission n, and the incident light quantity P Is multiplied by the above-described correction coefficient K to take measures against errors in the light amount AF of a bright subject.

The light amount P₀Uses IRED1 as the light source
And when the strobe light emitting unit 15 is used as a light source.
Will have different values. Therefore, two of the different values
P ₀Are stored in the EEPROM 17 in advance.

As described above, according to the above-described embodiment, the following ranging modes are selectively used according to the subject,
It is possible to provide a distance measuring device that does not have a weak object.

That is, for an object whose distance can be measured by the image signal, the passive AF obtained in step S1 of FIG.
The distance measurement in the passive mode, in which the triangular distance measurement in step S4 is performed using the value of (1), is performed.

In the case of an object whose distance can be clearly measured by the IRED, a pattern that can be clearly determined is used in step S8 by using the AF value of the IRED1 obtained in step S8.
An active triangulation mode for performing triangulation of 18 is executed.

Further, if the subject is at a long distance, the process proceeds to step S8 using the AF value by the IRED 1 in step S8.
The light amount ranging mode of the IRED in which the light amount AF of 20 is performed, the flash triangulation distance measurement mode in which the triangulation is performed in step S18 using the value of the AF by the flash emission in step S12, and the flash emission in step S12 The flash light amount ranging mode in which the light amount AF is performed in step S20 using the AF value according to (1) is executed.

By properly using these distance measurement modes, accurate distance measurement without erroneous switching determination or erroneous light amount determination is possible even in a bright scene.

In the above description, the integration time t _INT when the image signal is integrated to a predetermined level is determined in step S2 to determine the brightness of the stationary light, and the step S2 is performed.
At 6, the brightness was determined using the integration time. As a modified example, in step S2, a voltage integrated during a predetermined time may be obtained, and in step S6, the brightness may be determined using the integrated voltage.

[0076]

As described above, according to the present invention,
Conventionally, the distance measurement accuracy of a scene in which distance measurement was difficult in both passive AF and active AF has been improved, so that it is possible to provide a distance measurement device capable of performing stable distance measurement regardless of luminance and distance. Further, the camera equipped with the distance measuring apparatus of the present invention can perform distance measuring and focusing for selecting a scene.

[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 diagram illustrating a function of removing steady light.

FIG. 3 is a timing chart for explaining an operation for determining the brightness of the stationary light.

FIG. 4 is a diagram showing an example of a distance measuring sensor and an image signal output from the distance measuring sensor.

FIG. 5 is a diagram showing a positional relationship between a sensor array and a light projection pattern on the basis of a camera screen to which the present invention is applied.

FIG. 6 is a flowchart illustrating an operation of the distance measuring apparatus according to the embodiment of the present invention.

FIG. 7 is a timing chart illustrating operations of the IRED, the integration, and the strobe.

FIGS. 8A and 8B illustrate the operations of the IRED, the integration, and the strobe light. FIG. 8A illustrates a case in which t _INT is larger than t ₀ during passive AF even when the same integration amount is integrated in three IRED emission (dark). ) Timing chart, (b) is the same passive A
T _INT at the time of F is a timing chart of the time (at the time of Akira) was t ₀ or less.

FIG. 9 is a step S20 in the flowchart of FIG. 6;
9 is a flowchart for explaining a subroutine "light amount AF".

[Explanation of symbols]

Reference Signs List 1 infrared light emitting diode (IRED), 2 condenser lens, 3a, 3b sensor array, 3a ₁ light receiving element, 4a current detection circuit, 4b steady light removal transistor, 4c hold capacitor, 5 integration circuit, 5a integration amplifier, 5b Integration capacitor, 5c reset switch (SW), 6 comparator, 7 A / D converter, 10 CPU, 11 driver, 12 subject, 13a, 13b light receiving lens, 14 strobe circuit, 15 strobe light emitting unit, 16 focusing unit, 17 EEPROM, 18 release switch, 20 operation control section, 21 pattern judgment section, 22 correlation operation section, 23 reliability judgment section, 24 light quantity judgment section, 25 comparison constant circuit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 13/36 G03B 3/00 A F term (Reference) 2F112 AA07 AC03 BA03 CA02 EA07 FA07 FA14 FA29 FA45 2H011 AA01 BA05 BA14 BB04 DA08 2H051 BB07 BB09 BB20 CB20 CC10 CC11 CC12 CC16 CC18 CE07 CE21 DB01 EB07 EB19

Claims (4)

[Claims] 1. A first light source for projecting a first distance measuring light to an object, and a second light source which is stronger than the first distance measuring light to the object.
A second light source for projecting the distance measuring light, a sensor array for converting an incident light distribution from an object into an electric signal, and a sensor array output when the first distance measuring light is projected. First distance determining means for determining the distance to the object; and second distance for determining the distance to the object from the sensor array output when the second distance measuring light is projected. Determining means, based on an output level of the sensor array when not projecting the first and second distance measuring lights, the first distance determining means or the second distance determining means. A distance measuring device comprising: selecting means for selecting. 2. Extraction means for extracting only a reflected light component of the first distance measuring light from an output signal of the sensor array when projecting the first distance measuring light toward the object. The first distance determining means based on an output of the extracting means and an output level of the sensor array when not projecting the first and second distance measuring lights. 2. The distance measuring apparatus according to claim 1, wherein one of the first and second distance determining means is selected. 3. A sensor array for converting a distribution of light incident from an object into an electric signal, a light source for projecting light for distance measurement to the object, and a reflected signal when the light source is projected. A reflected signal light extracting means for extracting light from the output of the sensor array, a determining means for determining the output level of the sensor array when the light projecting light source is not operated, and a extracting means; According to the result of comparing the image signal output by the sensor array when the extracting means is not operated or the determination level switched by the output of the determining means with the sensor array output level when the light emitting source and the extracting means are operated. A distance measuring device for determining a distance according to a reflected light amount signal. 4. The projection light source includes a first projection light source and a second projection light source having different energies required for projection, and switches the first projection light source and the second projection light source according to an output result of the determination unit. The distance measuring apparatus according to claim 3, wherein