JPH10281762A - Distance-measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance-measuring device by which a distance can be measured quickly and precisely even when pulsating light is incident on a sensor for AF. SOLUTION: In a distance-measuring device, a plurality of subject images which are incident from different visual fields are detected, and a distance up tp a subject 8 is measured on the basis of the relative distance between positions of the plurality of subject images. The distance-measuring device is provided with a pulsating-light monitoring part 7 used to detect a change in light from an artificial lightsource which is turned on by an alternating current and which illuminates the subject 8 and with a CPU 10 which controls the detecting timing of signals of the subject images so as to correspond to the detection result of the change in the light. Even when the light which illuminates the subject 8 is light which is changed in an alternating current manner, the subject can be focused with high accuracy when the distance- measuring device is applied to a camera which can obtain a stable distance- measuring characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a distance measuring apparatus for measuring the distance to a subject by measuring the amount of light incident from the subject.

[0002]

2. Description of the Related Art Conventionally, a distance measuring device used for an image pickup device such as a camera is generally designed on the assumption that light illuminating a subject is constant.
Since the light is turned on by a commercial power supply, the light illuminating the subject often flows in a pulsating manner.

[0003] In order to reduce the influence of the AC light generated by artificial lighting on the distance measuring device, various techniques have been conventionally disclosed in, for example, JP-A-61-144504 and JP-A-56-14906. Proposed.

[0004] That is, in Japanese Patent Application Laid-Open No. 61-144504, an external light detecting section for detecting that a signal component of external light is included in a signal from a light receiving section, and external light detection is performed by the external light detecting section. A control unit that stops the calculation operation of the distance calculation unit when the operation is performed, and when the external light is detected by the external light detection unit, the distance detection is not performed. A technique relating to a distance detection device that prevents erroneous distance measurement due to extraneous light has been disclosed.

Further, in Japanese Patent Application Laid-Open No. 61-14906, even if the reflected light from the object to be measured includes a pulsating wave,
By detecting the section where the rate of change of the pulsating wave is the smallest, emitting a light beam for distance measurement in that section and receiving reflected light to perform signal processing, the output of an erroneous signal is prevented. A technology related to a distance detection device that realizes accurate distance detection is disclosed.

[0006]

However, in the technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-144504, distance measurement is stopped when harmful light enters due to fluctuations in light. Cannot be executed.

Further, the technique disclosed in Japanese Patent Application Laid-Open No. 56-14906 is limited to a technique for so-called active AF that separates distance measuring light projected from a camera side from background light. Was not applicable.

In the case of the active AF, the distance measuring light emission time is extremely short as compared with the time period of the change of the AC light source, and the distance measuring light may be projected at a place where the AC light source does not fluctuate. However, in the case of the passive AF, it is necessary to perform a long-time integration when the luminance of the subject is low, and it is difficult to avoid the influence of the AC fluctuation. It was expected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a camera using a so-called passive AF, which measures a distance by using information of an image of a subject. It is an object of the present invention to provide a distance measuring device for quickly and accurately measuring a distance even when the light is incident on an AF sensor.

[0010]

In order to achieve the above object, a distance measuring apparatus according to a first aspect of the present invention detects a plurality of subject images incident from different fields of view, and detects the positions of the plurality of subject image positions. In a distance measuring device that measures the distance to the subject based on the relative difference, AC lighting is performed, and a detection unit that detects a change in light from an artificial light source that illuminates the subject, and a detection result of the light change Control means for controlling the detection timing of the subject image signal in response.

In the distance measuring apparatus according to the second aspect, a light beam from an object incident through two apertures having parallax is imaged on a photoelectric conversion element array, and a two-image signal obtained thereby is obtained. In a distance measuring apparatus for detecting a relative distance to an object by detecting a relative interval, a monitor means for generating an output signal when an image signal from the photoelectric conversion element array reaches an appropriate accumulation level, and illuminating the object. Detecting means for detecting the presence of an artificial light source driven by an alternating current power supply and the rate of change of brightness over time, and correcting the level of the two image signals in response to the rate of change of brightness of the artificial light source over time And a correcting means for performing the correction.

A distance measuring apparatus according to a third aspect detects a plurality of subject images incident from different visual fields by a photoelectric sensor array, and measures a distance to the subject based on a relative difference between the plurality of image positions. In a distance measuring device, AC lighting is performed, and detection means for detecting a change in light from an artificial light source illuminating the subject, and responding to the image signal detection result and the change detection result, the subject image signal is detected. And a calculating means for calculating the distance to the subject in addition to the correction.

The first to third aspects have the following effects. That is, in the distance measuring apparatus according to the first aspect of the present invention, the detecting means detects the fluctuation of the light from the artificial light source illuminating the subject by alternating-current lighting, and the control means responds to the light fluctuation detection result. Thus, the detection timing of the subject image signal is controlled.

In the distance measuring apparatus according to the second aspect, when the image signal from the photoelectric conversion element array reaches an appropriate accumulation level by the monitor means, an output signal is generated, and the detection means illuminates the object. The existence of the artificial light source driven by the power supply and the rate of change of the brightness with respect to time are detected, and the level of the two image signals is corrected by the correction means in response to the rate of change of the brightness of the artificial light source with respect to time. You.

In the distance measuring apparatus according to the third aspect, the detecting means detects a change in light from an artificial light source that illuminates the subject by alternating-current lighting, and the calculating means detects the image signal detection result and the fluctuation detection result. , The subject image signal is corrected, and the distance to the subject is calculated.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In the following description, first, the output of the AF sensor is A / D-converted by the time until it reaches a predetermined determination level, second, the accumulation level of the AF sensor is monitored at the peak level, Third, it is assumed that the artificial light changes sinusoidally.

First, FIG. 1 shows the structure of a distance measuring apparatus according to a first embodiment and will be described. The first embodiment relates to accumulation timing adjustment, and is employed in an external light type two-image interval detection AF device, and a separately provided pulsating light monitoring unit 7.
Thus, the state of the pulsating light is detected by diverting the active AF light receiving circuit. When the pulsating light is in one of the increasing and decreasing states, the accumulation operation is performed, and otherwise, the accumulation operation is waited for a half cycle.

As shown in FIG. 1, light receiving lenses 1a and 1b are provided to receive an image of a subject 8, and a plurality of photo-detecting lenses 1a and 1b are provided at positions where the subject images are formed. A sensor array 2a comprising a row of diodes,
2b are arranged. Further, the sensor array 2
The outputs of a and 2b are sent to the CPU 1 via the A / D converter 3.
The output of the CPU 10 is connected to the inputs of the sensor arrays 2a and 2b via the integration control unit 4.

Further, a light receiving lens 5 is disposed at a predetermined position to detect a pulsating flow of the AC light source 9, and a sensor 6 for detecting pulsating light is disposed behind the light receiving lens 5. . The output of the sensor 6 is connected to the input of the CPU 10 via the pulsating light monitor 7.

In such a configuration, the image of the subject 8 is guided by the light receiving lenses 1a and 1b to the sensor arrays 2a and 2b composed of photodiode rows, received by the sensor arrays 2a and 2b, and photoelectrically converted. You.
The sensor arrays 2a and 2b are controlled by the integration control unit 4 and output photoelectric conversion signals according to the intensity of incident light. The output photoelectric conversion signal is converted into a digital value by the A / D converter 3 and input to the CPU 10 including a one-chip microcomputer or the like.

Here, this photoelectric conversion signal output and A / D
As a conversion method, a method of integrating the output photocurrent of the photodiode into a capacitor and counting the time when the integration result reaches a predetermined level can be adopted.

That is, as shown in FIG. 2A, the integral voltage V tends to increase with time t, but the amount of light, that is, the brighter the subject image, the longer the time required to reach the predetermined level V1. And as a result, the judgment time t1
Becomes shorter. That is, if the determination time t1 is short, it is determined to be "bright", and if the determination time t1 is long, it is determined to be "dark".

However, when the light of the artificial illumination 9 pulsating the subject 8 is irradiated, the integrated waveform is disturbed as shown in FIG. 2B, and the integrated waveform is changed as shown in FIGS. 2C and 2D. Depending on the state and timing of the pulsating flow as shown, even if the brightness is the same, an error occurs because the time to reach the predetermined level V1 becomes t2 or t3.

Therefore, in the first embodiment, in order to avoid this error, light from the subject 8 is received by the sensor 6 via the light receiving lens 5 and whether or not this light is pulsating is determined. The pulsating light monitoring unit 7 detects the result, and the
The CPU 10 controls the integration operation of the distance measurement in a control sequence (FIG. 3) described later.

Hereinafter, referring to the flowchart of FIG.
The control of the CPU 10 will be described. First, the CPU 10 detects how the light incident from the subject 8 fluctuates by the pulsating light monitor 7 (Step S).
1). The CPU 10 determines the timing to start the integration operation based on the result (Step S2).

More specifically, in the case of pulsating light as shown in FIG. 2C, integration is performed as it is, and when the illumination is pulsating as shown in FIG. The integration is started after waiting for the timing of half tM (steps S3 and S4). By such control, FIG.
Since the integration result as shown in (1) is always fixed to t1, the variation at the time of distance measurement is suppressed.

FIG. 4 shows the details of the pulsating light monitor (step S1). That is, the CPU 10 determines the period of the pulsating light by the pulsating light monitoring unit 7 (Step S).
5), integration is performed (step S6), and integration is performed again at a timing after a half cycle of the pulsating cycle (steps S7 and S).
8) The results of the two integrations of steps S6 and S8 are added (step S9), and an integration result is obtained in such a manner that t1 and t2 in FIG. 2B are averaged. Therefore, even in this case, stable distance measurement can be performed even under pulsating light.
When the cycle of the commercial power supply has been determined, in step S5, only detection of whether or not there is pulsating light is performed.

Next, FIG. 5 shows a specific configuration example of the pulsating light monitoring section 7 and will be described. In the figure, reference numeral 5 denotes a sensor comprising a photoelectric conversion element, reference numeral 11 denotes a preamplifier, and reference numeral 12 denotes a current amplification transistor. By these actions, the output photocurrent of the sensor is amplified and passed to the compression diode 13 as the collector current of the transistor 12. However, when the level of the compression diode 13 decreases, the one-side input of the operational amplifier 17 decreases.
The base of the transistor 15 rises, and the sensor output flows as the collector current of the transistor 15 without being amplified. That is, when the amplifier 17 is operating, the output of the sensor is hardly amplified. Even when the amplifier 17 stops operating, the base potential of the transistor 15 at that time is stored in the capacitor 16. Reference numerals 18 and 19 denote a diode and a constant current source for inputting the reference voltage Vref to the + terminal of the amplifier 17. Reference numeral 14 denotes a buffer circuit for monitoring the voltage of the compression diode.

In such a configuration, the operational amplifier 17
Is operating, the level of the compression diode 13, that is, the output of the buffer 14, is constant. However, when the operation of the operational amplifier 17 is stopped by the timing signal generating means 20, a variation from the photocurrent output from the sensor 5 at the time of the operation of the operational amplifier 17 is output to the buffer 14.

This will be described with reference to the timing chart of FIG. When the operation of the operational amplifier 17 is stopped at the timing of H in FIG. 6B when the pulsating light as shown in FIG. 6A is incident on the sensor 6, the output of the buffer 14 becomes As shown in FIG. That is, since the base potential of the transistor 15 is controlled by the voltage held in the capacitor 16 at the last timing of the operation, the fluctuation of the pulsating light is output as Vp.

The CPU 10 includes a comparator 14b
It is determined whether this level is higher or lower than Vref. With this operation, the CPU 10 can determine whether the pulsating light is changing in the direction of increasing or decreasing depending on whether Vp is higher or lower than the reference voltage Vref.

Hereinafter, referring to the flowchart of FIG.
An operation of an application example of the first embodiment of the present invention using the pulsating light monitor 7 will be described. In this application example,
The CPU 10 sets the above V at a timing after a predetermined time interval.
The magnitude relationship of p is detected (steps S21 and S22), and distance measurement is performed only when these satisfy the relationship of Vp1> Vp2 (steps S23 and S24). As a result, FIG.
The distance measurement is performed only in one of the cases (c) and (d), and the time until the integration reaches V1 shown in FIG. 2B does not vary between t1 and t2. Accuracy can be improved.

As described above, in the distance measuring apparatus according to the first embodiment, even if the light illuminating the subject is light that fluctuates in an alternating manner, stable distance measuring characteristics can be obtained and the distance measuring apparatus can be applied to a camera. In this case, highly accurate focusing can be achieved.

The circuit configuration of the pulsating flow monitor unit 7 shown in FIG. 5 is the same as that of the active AF light receiving circuit, so that the sensor is used as the active AF sensor and the distance measuring light is projected. In addition, there is also an application that enables more accurate distance measurement by projecting light from a light projection unit (not shown) and using an active AF together when the subject is dark or has no contrast, etc. Can be expected.

Next, a distance measuring apparatus according to a second embodiment will be described. The second embodiment relates to accumulation timing adjustment, and repeatedly monitors the accumulation level of an AF sensor, and detects the state of pulsating light based on a change in time until a monitor signal is output. Then, when the pulsating light is in either the decreasing tendency or the increasing tendency, the accumulation operation is performed, and if not, the accumulation operation is waited for a half cycle.

FIG. 8A is a diagram showing a configuration of a distance measuring apparatus according to the second embodiment. As shown in the figure,
In the second embodiment, the output of the sensor arrays 2a and 2b is different from that of the passive distance measuring apparatus having the same configuration as that of FIG. 1 including the light receiving lenses 1a and 1b, the sensor arrays 2a and 2b, the A / D converter 3, and the like. An integration monitor unit 4 for monitoring the integration level of the photocurrent is provided so that the CPU 10 can perform control for keeping the integration level within the dynamic range of the signal level defined by the power supply voltage of the circuit. Such a contrivance is not possible with passive AF.
In the second embodiment, the above-described pulsating light detection is performed using the output of the monitor unit 4.

Here, FIG. 8B shows an example of the integration monitor section 4 and will be described. In FIG.
Reference numerals 21c to 21c denote respective photodiodes constituting the sensor array, and reference numerals 22a to 22c denote integration capacitors for integrating these output photocurrents. Symbol 25a-
25c discharges these capacitors,
This is a reset switch for initializing the integrated voltage. Sign 2
Reference numerals 3a to 23c denote comparators for comparing the reference voltage Vref with the integrated voltage when integration is started after the reset switch is turned off.

The reset Sw is controlled all at once by the integration control unit 26. However, when at least one of the comparators 23a to 23c is inverted, the OR circuit 24 outputs an OR signal.

Although not explicitly shown in FIG. 8B,
The voltage stored in the integration capacitors 22a to 22c is configured by a combination circuit of a voltage hold circuit and a multiplexer circuit or an analog shift register circuit configured by the number of bits equal to the number of pixels of the sensors 21a to 21c. The voltage information of each bit is sequentially read out after the integration operation is terminated, and the A / D signal shown in FIG.
The conversion unit 3 performs A / D conversion.

FIG. 8C is a timing chart showing the operation of the above circuit. As shown in FIG.
Assuming that the interval between the OFF timing of W and the generation timing of the OR signal is Tor, this is a value dependent on the maximum value of the amount of light input to each sensor. By switching Vref or switching the capacitance of the capacitors 22a to 22c, the sensitivity can be switched, and the integration control can be completed within a predetermined dynamic range within a predetermined time regardless of the brightness level of the subject. It becomes possible.

The characteristic of the second embodiment is that the pulsating light is detected by applying the Tor signal, and a special sensor or circuit is required as in the case of FIG. Since it is not necessary, it can be constructed inexpensively and compactly.
When the subject is illuminated with the pulsating light, the time of Tor differs depending on the state of the pulsating light at that time due to the phenomenon shown in FIG. According to the above principle, the pulsating light is detected in the second embodiment.

Hereinafter, referring to the flowchart of FIG.
The above operation will be described. As shown in FIG. 9, if Tor is detected twice over a predetermined time corresponding to a half cycle of the pulsating light source (steps S31 to S33), the light decreases at one timing and the light decreases at the other timing. To increase,
It is possible to predict which of the states shown in FIGS. 2C and 2D the pulsating light at the time of distance measurement will be.

Therefore, here, the integration is started only when Tor1 is larger than Tor2 (step S34), and the state of the pulsating light at the start of the integration is made uniform (step S35). By such control, integration is always performed under constant conditions, so that the result does not change every time the distance is measured, and the accuracy is improved.

Next, FIG. 10 shows the configuration of a distance measuring apparatus according to a third embodiment, and will be described. In the third embodiment,
The accumulation process is sampled to determine the suspension of the accumulation, and the peak value of the accumulation level is monitored by a peak detection circuit as described later, and the continuation of the integration is determined again. is there.

In the figure, a light receiving element constituting a sensor array, sensors 21a to 21c reset switch 25a
(The 25b and 25c are not shown for simplicity.) Since the integration capacitors 22a to 22c have already been described, their description will be omitted.

Reference numeral 31 denotes a current source, and reference numerals 30a to 30c denote monitoring transistors, which monitor the integrated voltage based on a base and select the largest one of the integrated voltages of the capacitors 22a to 22c in the buffer circuit 32. Input as a voltage close to the emitter voltage (VBE) (FIG. 11)
(A)). Therefore, when this buffer output VM is monitored by the A / D converter 33, the CPU 10 receives the largest amount of light among the sensors 21a to 21c and outputs the largest photocurrent, but determines the integrated voltage VCMAX. it can.

Hereinafter, the distance measuring apparatus having such a configuration will be described.
A method for detecting pulsating light will be described with reference to FIGS. FIG. 11A shows an integrated waveform when a subject is irradiated with DC light, while FIG. 11B shows an integrated waveform when pulsating light is irradiated. In these figures, the horizontal axis represents time, and the vertical axis represents voltage. FIG. 11B shows how the monitor voltage is undulating under the influence of pulsating light. From these figures, depending on the condition of the pulsating light, t1,
It can be seen that the slope of the integration at t2 changes.

The operation of the third embodiment will be described below with reference to the flowchart of FIG. In this sequence, the integrated voltages at the times t1 and t2 are monitored, and the rate of change over time is compared to suppress the influence of the pulsating light.

That is, first, after disclosing the time measurement of the timer (step S51), the CPU 10 starts integration (step S52), monitors the integrated voltages at the timings of t1 and t2, and outputs the results as V1 and V2. (Steps S53 to S56).

Here, if the time from the start of the integration to the time t1 is equal to the time from the time t1 to the time t2, if there is no pulsating light, the rate of change is equal, and V1 is equal to V2 -V1. On the other hand, if there is pulsating light,
As shown in FIG. 1 (b), at some times, V1> V2-V1.

Since such a variation is caused by a disturbance in the distance measurement result, in the third embodiment, the integration is continued in the step S60 only when the condition of V1> V2-V1 is satisfied in the step S59. Thus, under other conditions, the integration voltage is reset and the integration is performed again in step S62. At this time, the component start timing is shifted by a half cycle of one cycle of the pulsating light.
> V2-V1.

As described above, in the third embodiment, the pulsating light determination is performed by monitoring the state of integration of the sensor that receives the strongest light input to the sensor array. Therefore, no special sensor is required. Further, since the monitor is performed while integrating, pulsating light is detected simultaneously with the integration, and a high-accuracy distance measurement with a small time lag can be performed without performing a useless integration operation.

Next, a fourth embodiment will be described with reference to FIGS. In the fourth embodiment, the sensor output is corrected in accordance with the state of the pulsating flow, and the accumulation level of the AF sensor is repeatedly monitored to detect the state of the pulsating light based on the output of the AF sensor. The output of the AF sensor is corrected in accordance with the change state of the pulsating light, and the accumulation result is appropriately corrected.

The operation of this embodiment will be described below with reference to the flowchart of FIG. In the fourth embodiment, the pulsating light state is monitored before and after the distance measurement (step S42), instead of the pulsating light countermeasure of performing integration in accordance with the pulsating light timing as described above (steps S41 and S41). 43) As a result, a magnitude determination is performed based on M1 and M2 (step S44), and the AF result is corrected (steps S45 and S46), thereby preventing deterioration of AF accuracy due to pulsating light.

For example, as shown in FIG.
In the integrated waveform under the pulsating light illumination, the error ΔAD affects the increasing direction or the downward direction depending on the state of the pulsating light at that time. Therefore, at the start of the integration (step S20)
Pulsating light M1 at the time of the integration signal (step S).
22) is higher than the level M2 at
As shown in FIG. 4 (b), it is considered that the integration level has decreased with respect to the ideal, and conversely, it is considered that the integration level has increased.

Based on the above concept, step S2
In M3, when M1 is larger than M2, the correction in the + direction is defined in step S24, and conversely, when step S23 is branched to N, the correction in one direction is performed in step S25. Do.

As described above, according to the fourth embodiment,
As in the first embodiment described above, a stable distance measurement can be quickly performed under pulsed light without shifting the timing or repeating the distance measurement many times.

The above embodiments of the present invention include the following inventions. (1) a distance measuring unit that includes a storage-type photoelectric sensor and optically measures the distance from the device to an object; and a detecting unit that detects the presence of incident light whose brightness by an AC light source periodically changes. The distance measuring means performs the accumulation operation when the AC light source is detected, when the brightness of the incident light by the AC light source is increasing, or when the brightness is decreasing. And control means for controlling the operation timing of the distance measuring device. (2) The detection means includes storage means for storing the light quantity at a predetermined timing, and fluctuation component detection means for detecting the light quantity at the next timing as a difference from the light quantity at the predetermined timing. The distance measuring device according to 1). (3) The detecting means detects a light fluctuation from a light quantity incident on the subject image detecting means at a predetermined timing and a light quantity incident on the accumulation type photoelectric sensor at a timing different from this timing. The distance measuring device according to (1). (4) Light beams from the object incident through the two apertures having parallax are respectively imaged on the storage-type photoelectric conversion element array, and the relative distance between the two image signals obtained thereby is detected and the object is detected. In a distance measuring device for obtaining a distance to an object, a control means for initializing an accumulation level of the photoelectric conversion element array and controlling an accumulation operation, and an image signal from the photoelectric conversion element array reaches an appropriate accumulation level. And a monitor means for generating an output signal when the monitor signal is generated. The time from the start of accumulation of the photoelectric conversion element array to the generation of the monitor signal is repeatedly measured, and this time is a predetermined time with respect to the previous measurement result. A distance measurement device that invalidates the latest accumulation result when

[0059]

As described above, according to the present invention, in a camera using a so-called passive AF, which measures a distance by using information of an image of a subject, the pulsating light is reflected by the AF.
A distance measuring device for performing quick and accurate distance measurement even when the light enters a sensor for use can be provided.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a relationship between time and integration time of a sensor.

FIG. 3 is a flowchart illustrating control of a CPU.

FIG. 4 is a flowchart showing details of a pulsating light monitor in step S1 of FIG. 3;

FIG. 5 is a diagram showing a detailed circuit configuration of a pulsating light monitoring unit 7;

FIG. 6 is a time chart showing the operation of the pulsating light monitoring unit 7;

FIG. 7 is a flowchart illustrating an operation of an application example of the present embodiment using the pulsating light monitoring unit 7.

FIG. 8 is a diagram for explaining a distance measuring apparatus according to a second embodiment.

FIG. 9 is a flowchart showing an operation of the distance measuring apparatus according to the second embodiment.

FIG. 10 is a diagram showing a configuration of a distance measuring apparatus according to a third embodiment.

FIG. 11 is a diagram showing a method for detecting pulsating light in the third embodiment.

FIG. 12 is a flowchart showing an operation of the distance measuring apparatus according to the third embodiment.

FIG. 13 is a flowchart showing an operation according to the fourth embodiment.

FIG. 14 is a timing chart showing an operation according to the fourth embodiment.

[Explanation of symbols]

 Reference Signs List 1 light receiving lens 2 sensor array 3 A / D converter 4 integration controller 5 light receiving lens 6 sensor 7 pulsating light monitor 8 subject 9 AC light source 10 CPU

Claims (3)

[Claims] A distance measuring device that detects a plurality of subject images incident from different visual fields and measures a distance to the subject based on a relative difference between the plurality of subject image positions; Detecting means for detecting a change in light from an artificial light source that illuminates the subject; and control means for controlling detection timing of the subject image signal in response to a result of the light change detection. Distance measuring device. 2. A light beam from an object incident through two openings having parallax is imaged on a photoelectric conversion element array, and a relative interval between two image signals obtained thereby is detected. A distance measuring device for determining a distance to the object, a monitor means for generating an output signal when an image signal from the photoelectric conversion element array reaches an appropriate accumulation level, and an artificial device driven by an AC power supply for illuminating an object. Detecting means for detecting the presence of a light source and a change rate of brightness with respect to time; and correcting means for correcting the level of the two image signals in response to the change rate of brightness of the artificial light source with respect to time. A distance measuring device characterized by the above-mentioned. 3. A distance measuring device for detecting a plurality of subject images incident from different visual fields by a photoelectric sensor array and measuring a distance to the subject based on a relative difference between the plurality of image positions. Detecting means for detecting a change in light from the artificial light source illuminating the subject; and responding to the image signal detection result and the change detection result,
Calculating means for correcting the subject image signal and calculating a distance to the subject.