JP2002206923A - Range finder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately find a range both when bright and when dark. SOLUTION: This range finder has a light projection source (IRED 4a or stroboscope 5a) for projecting pulselikely range finding light toward a subject 21, and sensor arrays 3a, 3b for converting a light distribution from the subject 21 into an electric signal, and provided further with a means (a stationary light removing part 7, a pattern determining part 11, an A/D conversion part 16) for extracting a reflection signal light component obtained by the sensor arrays when the prescribed projection source is projection-driven selectively, a means (integrating determination part 17) for integrating an output from the means synchronizingly with the pulselike projection, a means (luminous energy determining part 14) for determining brightness of the subject 21, and a means (control part 1a) for determining a pulse width of the pulselike projection in response to an output from the means. A reliability determining part 13 determines the brightness based on output results of the sensor arrays 3a, 3b when the range finding light is not projected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an auto focus
(AF) The present invention relates to an improvement of a distance measuring device used for a camera or the like.

[0002]

2. Description of the Related Art AF techniques for cameras are roughly classified into two types: a passive type that uses a subject image and an active type that uses ranging light projected from the camera. However, each of these methods has a drawback based on the principle of the method, so a hybrid AF method (hereinafter, referred to as “hybrid AF”) combining both methods has been proposed.

[0003] In particular, regarding active AF, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 3-133014 proposes projection of distance measuring light (for example, switching of the number of times of light emission) and switching of the number of times of integration in accordance with the state of distance measurement caused by subject conditions to improve measurement accuracy. This is used by many cameras to achieve a very large effect.

[0004]

However, this is
Only the number of times of light emission is changed, and the time of one light emission is not changed. In a hybrid AF using a sensor array, the integration noise generated during light emission integration greatly affects the error in distance measurement. Therefore, simply increasing the number of integrations and extending the distance measurement time may degrade the accuracy depending on the situation. I was invited. Therefore,
In the hybrid AF, it is desired to reduce the number of integration under good conditions as much as possible in order to avoid switching noise when a difference between light emission and non-light emission is obtained.

However, at present, only by switching the number of times of light emission,
There is no technique for changing the time of one light emission, and there is no technology that considers the adjustment of the number of light emissions. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a distance measuring apparatus which can perform accurate distance measurement even in dark and bright conditions.

[0006]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention takes the following measures. The present invention is an improvement on the above-described hybrid method or combination method, and addresses the above-mentioned drawbacks by combining active mode and passive mode with optimal integration conditions, and enables stable and accurate distance measurement regardless of luminance and distance. The distance measuring device described above is proposed.

That is, the present invention converts, for example, the distribution of light incident from an object to an electric signal in order to prevent a failure in distance measurement judgment or calculation due to an error during removal of stationary light, which is a specific operation in active AF. Sensor array, a light source for projecting distance-measuring light to the object in a pulsed manner, and an extracting means for extracting a reflected signal light component obtained from the sensor array when the light source is driven to project light. Integration means for integrating the output of the extraction means in synchronization with the pulsed light emission, determination means for determining the brightness of the object, and the pulsed light emission of the object according to the output of the determination means A distance measuring device including a determining unit for determining a pulse width is proposed. Further, the present invention proposes a distance measuring device in which the determination means determines the brightness based on an output result of the sensor array when the non-light projection for distance measurement is performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The distance measuring apparatus of the present invention can be used not only in a bright case but also in a dark case by appropriately switching the type of light source and the integration time of light emission from the light source according to the brightness of the subject. It has been improved to enable accurate ranging.

Normally, to reduce the number of integrations in the AF method of integrating up to a predetermined amount, it is sufficient to extend one integration time. However, if the number of integrations is reduced in a bright scene, the noise canceling effect is lost and conversely. Accuracy deteriorates. Therefore, the present invention has one feature in a device where the integration time is changed according to the luminance. Before describing the configuration realizing this feature in detail, FIG. 1 shows the basic configuration of a distance measuring apparatus according to the present invention, and then the present invention will be described in detail from FIG.

(First Embodiment) As shown in FIG. 1, in a distance measuring apparatus according to the present invention, sensor arrays 3a and 3b in which pixels for light receiving elements are arranged are arranged so as to face an object 21 to be measured. Has been established. Further, in order to form an image of the subject 21 here, two light receiving lenses 2a and 2b are provided in front of the sensor arrays 3a and 3b with a focal length f, and a parallax B is provided between these lenses 2a and 2b. It is configured to obtain the subject distance L based on the “principle of triangulation”.

The image of the subject 21 formed on the two sensor arrays 3a and 3b according to the magnitude of the subject distance L changes the relative position with respect to each lens optical axis. A / D conversion means (A / D conversion unit: converter 16) for detecting this
Are integration outputs from the sensor arrays 3a and 3b (however, in this case, the integration circuits constituting the integration means are the sensor arrays 3a and 3b).
b is included in each pixel. ) Is converted into a digital signal, and an arithmetic and control unit (control unit: CPU 1) including a one-chip microcomputer or the like is provided with two sensor arrays 3a and 3
The digital image signal b is compared to detect the relative position difference and calculate the distance.

In order to check whether or not the images detected from the two sensor arrays 3a and 3b belong to the same subject 21, the CPU 1 operates a correlation operation means (correlation operation unit) for detecting a relative position difference between the images. 12) and a function of a pattern determining means (pattern determining unit 11) for checking whether or not the image pattern is suitable for distance measurement. The CPU 1 further includes
When the degree of coincidence of the image when the relative position error is detected and the pattern determination result of the image indicate that the pattern is low contrast, a repetitive pattern, a monotonically increasing, or a monotonically decreasing pattern, it is determined that the reliability of the distance measurement is low. It has reliability determination means (reliability determination unit 13).

The distance measuring apparatus further includes light amount determining means (light amount determining unit 14) for projecting a distance measuring light at the time of the stationary removal and determining the amount of incident light reflected and incident on the subject 21. The control amount of the focusing means (focusing unit 9) is determined based on the result of each function. Also, the CPU 1
It detects the input state of the release switch 8, controls the camera photographing sequence, controls the emission of the above-mentioned IRED 4a via the driver 4b as needed at the time of distance measurement, and controls the strobe light emitting means (strobe device 5a). The light emission of the strobe light emitting unit is appropriately controlled via the electronic flash.
The distance measuring apparatus further includes a determination unit (light amount determination unit 14) for determining the brightness of the object, and determines the pulse width of the pulsed light emission according to the output of the determination unit. Note that this determination means is provided by the sensor arrays 3a and 3b when the distance measuring light is projected.
Is configured to determine the brightness based on the output result of (1) (details will be described later).

Here, the distance measuring apparatus having the above-described configuration has to be considered when measuring the distance, that is, the light which is illuminating the subject and which is caused by the steady light such as sunlight or artificial lighting. Regarding the removal function for components, FIG.
The circuit configuration and operation will be described in detail based on FIG.
The light receiving element 3a1 shown in FIG. 2A corresponds to, for example, one pixel constituting a sensor array for detecting an image signal. Photocurrent I output from here according to the amount of incident light
_{The p} flows to GND via the constant light removal transistor 7a. The current detection circuit 7c controls the gate voltage of the transistor 7a so that no current flows in the integration circuit including the integration amplifier 16a, the integration capacitor 16b, the reset switches 16c and 16d, and the like.

The hold capacitor 7b is provided for fixing the gate potential. In this fixed state,
For example, when the infrared light emitting diode 4a emits light, and the distance measuring light is emitted in a pulsed manner to the subject 21 through the condenser lens 4, and the current detection circuit 7c is deactivated, the pulsed light is emitted. When the switch 16d is turned on, only the photocurrent corresponding to the pulsed light is input to the integrating circuit, and the output of the integrating amplifier 16a is output to the integrating circuit. A photoelectric conversion voltage based on the pulse light for distance measurement is output. Therefore, if this output is A / D converted, reflected light amount data corresponding to the reflected signal light can be detected.

However, as the steady-state photocurrent _Ip increases in a bright scene, an error component erroneously input to the integration circuit increases due to the influence of thermal noise, shot noise, and the like. In addition, the circuit is easily affected by the offset error of the circuit. In addition, in the case of a bright scene as described above, it is difficult to accurately detect the amount of reflected light as it is. Therefore, in the present invention, in order to remove these random noise components, when the brightness of the subject 21 is brighter than a predetermined brightness. In
The distance measurement operation is repeated many times, and the distance measurement result is averaged. By increasing the number of integrations in this manner, the effect of this averaging can be obtained, so that the ranging accuracy is improved. Therefore, when the light is bright, the control is performed so as to increase the light emission and the number of integration.

On the other hand, when the image is dark, there is no need to increase the number of integrations since the above-mentioned random noise is small.
Conversely, when the number of integrations is increased, the influence of switching noise generated at the time of integration increases, and the degree of influence differs for each sensor constituting the sensor array. For example, originally
Even in a situation where a reflected signal light pattern having a smooth waveform as shown in FIG. 12A should be obtained, if one light emission integration time is shortened to increase the number of integrations, as shown in FIG. 12B. In addition, the switching noise of each sensor pixel becomes a remarkable pattern. An image signal containing such a noise component easily causes an error when comparing the patterns of the left and right sensor arrays, and increases the probability of erroneous distance measurement. In other words, it is better to reduce the number of integrations in order to suppress switching noise. Conversely, to reduce random noise such as thermal noise that occurs when the luminance is high, increase the number of integrations and perform averaging. Better.

Therefore, in the distance measuring apparatus of the present invention, the accuracy of the distance measurement is improved by switching the light emission integration time and the number of times of integration according to the brightness. In addition, since the light amount of the IRED 4a decreases due to the generated heat as the energizing time becomes longer (see FIG. 12), it is advantageous in terms of S / N to shorten the light emitting time and measure the distance while cooling naturally. Focusing on this, the following is implemented.

In order to determine the brightness of the stationary light,
As a non-operating current detection means 7c, after once ON the reset switch 16c, as shown in FIG. 2 (b), pouring the stationary light current I _p to the integrating circuit, until the integrated voltage reaches a predetermined level V _{c Compute} time t _INT with comparator 1
7 may be used for detection. For example, in a bright scene, _tINT is short, and in a dark scene, _tINT is long. Therefore, the brightness can be determined only by counting the _tINT . At this time, IRED4
a is controlled so as not to operate.

In the present invention, an image signal output from a predetermined area by the distance measuring sensors 3a arranged as shown in FIG. 3A has a low contrast as shown in FIG. FIG. 3C shows a repeated pattern as shown in FIG.
If it is a monotonous change pattern as in (d),
Further, when the reliability of the result of the correlation calculation is low, the light projecting means 4a is projected to measure the distance based on the pattern of the reflected signal light.

A mask for forming a pattern may be provided in front of the light projecting lens 4, or a pattern of the light emitting section itself may be used. When the signal light reflected by the IRED 4a is small, the distance measurement is performed by strobe light projection, which has a larger light quantity than the IRED. However, in this case,
Since there is no specific pattern in the reflected signal light, in many cases, the signal light distribution has a low contrast as shown in FIG.

FIG. 9 shows the positional relationship between the sensor array 3a (3b) and the light projection pattern based on the screen 20 of the camera according to the present invention. The monitor area of the sensor array 3a is located at the center of the screen. Reference numeral 3c indicates that the exposure must be controlled by irradiating the entire screen with the strobe light, and the pattern becomes wide as indicated by reference numeral 5b.
Forms an infrared light pattern as indicated by reference numeral 4c. The mode in which the distance measuring apparatus measures the distance based on the relative position difference of the image signal of the object to be measured without projecting the light for distance measuring as described above is referred to as “passive AF”. The ranging mode that involves the above-described steady light removal operation and that involves the projection of light such as an IRED 4a or a strobe is referred to as “active AF”.

4 and 5, the operation of the distance measuring apparatus according to the first embodiment of the present invention will be described with reference to a flowchart, and the operation control thereof will be specifically described. FIG.
3 shows the procedure of the distance measuring operation of this distance measuring apparatus. First, the distance measurement (passive AF) in the passive mode is performed (S1), and an integration time t _INT when the image signal is integrated to a predetermined level is obtained (S1).
2).

The reliability of the passive AF is determined by the above-mentioned "pattern determination" or by the result of the correlation operation (S3). If the reliability is high, the flow branches to step S29, where triangulation is performed based on the two image signal positions. The distance is calculated based on the distance (S29), and the process returns. On the other hand, if the reliability of the passive AF is low, the IRED
Perform "pre-ranging" using. At this time, the pulse light for a predetermined time is projected n times and the integrated voltage V is applied by the A / D conversion means.
_{An INT} is obtained (S4). Light IRED as the integrated voltage V _INT is large it can be determined that the bright not reach sufficiently object. Conversely, if V _INT is small, the intensity of the IRED is insufficient, so a more powerful strobe light projection is performed. At this time, however, the steady light component such as sunlight or artificial lighting that illuminates the subject as described above is used. Without consideration, a correct judgment cannot be made.

Accordingly, in order to detect the stationary light component, the brightness is determined in step S5 using the integration time monitoring result t _INT (the result in step S2) during the passive AF in step S1 (S5). ). That is, the determination voltage V ₁ , which determines the magnitude of the integrated voltage V _INT during the IRED pre-integration in S4 by comparing with the predetermined time t ₀ ,
To determine the V _2. If t _INT is a short time value and it is determined that it is bright, a comparison is made between V _INT and a determination voltage V ₂ greater than V ₁ (S6). Also, if a long small t _INT is stationary light in dark scenes comparing V ₂ constant smaller than V ₁ and V _INT (S7). Thus, it is determined whether the distance measurement is performed by using the IRED as the projection light source or the distance measurement is performed under the light projection by the strobe device. In addition,
This integrated voltage may be implemented such that V _INT selects the integrated voltage of the sensor having the largest incident light amount among all the sensors constituting the sensor array, or the integral voltage having the largest incident light amount of the predetermined area of the sensor array. May be selected.

In the steps S8 and S11, the distance measurement operation in the active mode using the light of the IRED or the light of the strobe is performed as the "main distance measurement" by the light source selected in this way. In this method, light emission integration is repeated until light emission reaches a predetermined voltage with light emission for a predetermined time. If the projection light source to be used is an IRED, a subroutine "IRED-AF" (S8a to S8d) is performed in step S8.
Execute That is, the luminance of the object is measured (S8a),
The integration time is switched according to the luminance. Specifically, in the case of high luminance, the emission time is set short (S8c), otherwise the emission time is set relatively long (S8b),
Light is emitted and integration processing (S8d) is performed. After that, the end of the integration is controlled in the determination loop of the following steps S9 and S10.

If the result of determination step S7 is that the projection light source to be used is a flash device, steps S11 and S1 are performed.
Control is performed as follows in the loop of S2 and S13. That is,
If the light integration is performed a predetermined number of times or more, energy is wasted and the time lag is affected.
At 10, S13, the integration process is completed at a predetermined time (S13).
12) The integration time limiter n2 is provided to control the end timing by the number of times (S13).

After the above distance measurement, a result P obtained by integrating the amount of reflected light (ie, a value obtained by dividing the integrated voltage V _INT by the number of integrations)
Based on the result of (S20) and the pattern determination (S21), it is determined whether or not triangulation can be performed (S22). At this time,
The light emission time is switched according to the brightness of the subject as shown in FIG. If the reflected light image signal allows triangulation, triangulation is performed in step S24 (S24). On the other hand, if the pattern is not sufficient or if it is determined in step S25 that the reliability of the triangulation is low (S25),
In step S23, light amount AF based on the previously reflected light amount P is performed (S23).

As described above, when the amount of reflected light is examined by projecting light, a distance based on the fact that a large amount of light returns from an object at a short distance and a small amount of light returns from an object at a long distance. Depending on the measurement method, the distance measurement method is effective even for a subject having no contrast. However, in this case, it is assumed that the reflectance of the subject is within a predetermined range.

FIG. 6 and FIGS. 7A and 7B show the results of the processing based on the above-described flowchart (FIG. 4) in a timing chart. FIG. 6 shows the IRE
Pre-distance measurement result when D is emitted three times (V when n ₀ = 3)
_INT) is determined that it can not distance measurement with light of IRED be at V ₁ or less, an example is shown in which the transition to the distance measuring operation by the strobe light. Flash device has ended light emission so reaches the integral determination voltage V _c at five emission.

FIGS. 7A and 7B show three IREs.
In the light emission of D, when t _INT during passive AF is greater than t ₀ (dark) and when t _INT is less than t ₀ (bright), the determination voltages are V ₂ , V ₁ even when integrating by the same integration amount. This shows that the actual distance measurement in the latter half is switched to IRED or strobe light by switching. As described above, such a measure is taken to prevent the photocurrent _Ip from increasing when the image is bright and noise to be easily added to the sensor and the hold transistor, and to integrate it and to integrate it more than it actually is. If such measures are 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.

Therefore, even in such a case, the distance can be correctly switched to the strobe-based distance measurement by the device of the present invention, and accurate distance measurement with a sufficient amount of reflected light can be performed. In addition, when strobe light emission is unnecessary because the distance is sufficiently close, distance measurement using an IRED with lower power consumption can be performed, and an energy saving effect can be obtained.

Next, control 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 with reference to the flowchart shown in FIG. Steps S30 to S34 are the integration time t for passive distance measurement.
_This is a determination process when the correction coefficient K of the light amount AF is switched by _INT . Assuming that t ₀ <t ₁ , the above step S3
When branching to YES at 0, it is determined that the scene is very bright, and the above step S30 is NO, and the above step S3
If 1 also branches to NO, it is determined that it is a dark scene, and if it branches to YES in step S31, it is determined that it is a scene of intermediate brightness.

Since it is not necessary to consider a noise error in a dark scene, the correction coefficient K in step S33 is 1 (S33).
(S34), and further reduced to 1/4 (S34).
32), in the subsequent calculation in step S35, "long distance" is set. That is, such adjustment of the correction coefficient K is one measure against the fact that noise and offset components are easily integrated in a bright scene to produce an output on the short distance side. That is, for example, when calculating the reciprocal _VL of the subject distance x proportional to the amount of extension of the focusing lens by an AF camera or the like, the light quantity P ₀ reflected from the 1 m subject in one light emission integration and the number of times of light emission n , By multiplying the above-mentioned correction coefficient K by a calculation formula using the incident light amount P (S
35) addresses the error in the light amount AF for a bright subject.

Therefore, by taking such measures, it is possible to perform accurate distance measurement not only in a dark scene but also in a bright scene without being affected by noise in a bright scene.

(Second Embodiment) Next, a distance measuring apparatus according to a second embodiment of the present invention will be described. However, since the basic configuration of this device is equivalent to that shown in FIG. 1, the description will be omitted, and a detailed description will be given focusing on the characteristic portions from FIG. FIG. 10 is a block diagram showing a stationary light removing circuit with improved signal light extraction performance. The stage preceding the current detection circuit 7c in the figure is substantially the same as the circuit configuration illustrated in FIG. 2 described in the first embodiment, and the reflected signal light by the pulse projection of the IRED 4a is converted into a photocurrent. It is output as an output of the current detection circuit 7c. However, the current detection circuit 7
Due to the error of c and noise, the output strictly dependent on the stationary light is superimposed on this output as described above. still,
This error is called a “hold error”.

Therefore, in the second embodiment, two rows of integration circuits are prepared, and the integration capacitor 16b for the integration amplifier 16a is controlled so that the output current when the IRED 4a is not projecting light is input (that is, the integration current is not input). , Switch 16d to A
Side is turned ON), and the integration capacitor 16b is connected to the IRE.
The output current at the time of light emission of D4a is input (that is,
The switch 16d is controlled to be ON to the B side.

Then, the IRED 4a is set to a duty of 50%.
And the switch 16d is set to A in synchronization with
2 obtained by alternately turning ON the side and the B side.
A difference amplifying means (difference amplifying unit 16h) calculates the difference between the two integration results.
Then, the distance measurement control is performed as shown in the time charts of FIGS. 11 (a) and 11 (b).

FIG. 11A shows that one light emission time is represented by t.
The timing chart when _IRED1 is set is shown.
That is, first, the switches 16c, 1 of the two integrating circuits
After the output is initialized by controlling ON of 6g with a predetermined Reset signal, the IRED 4a is turned ON / OFF.
When the switch 16d is turned on to the B side and turned off to the A side when it is off, the current at the time of light emission (signal + hold error)
And the current during non-light emission (for the hold error) is integrated. As a result, the difference (that is, the output of the difference amplifying unit 16h) becomes a more accurate reflected light signal from which the hold error has been removed.

FIG. 11B shows the emission time of the IRED as t.
_This is an example in which the length of _IRED2 is set to be twice as long as that of FIG. 11A, and a predetermined integration amount of the reflected signal is obtained with a small number of light emission integrations because one integration time is long. As described above, in a dark scene, switching noise that increases each time light emission integration increases has an adverse effect on ranging accuracy, due to random noise that is canceled by an increase in the number of integrations (see FIG. 12B).

Therefore, in the second embodiment of the present invention, in order to reduce switching noise in a dark scene, FIG.
In the integration as exemplified in FIG. 1 (b), one integrated light emission time is extended. Further, in a bright scene, it is considered that it is more accurate to remove random noise due to thermal noise more serious than switching noise by averaging and smoothing by repeating integration processing, so that light emission as shown in FIG. Performs ranging with a short integration time but a large number of times. At this time, the portion of one light emission where the light amount is large (see,
Since the distance measurement can be performed using (t _IRED1 in FIG. 13), the signal component can be made larger than the noise component N, and the S / N ratio is improved.

Such an IRED active mode AF
The control procedure for switching the light emission time is shown in FIG.
It is represented like a chart. In other words, during pre-integration (Fig.
4 integration time t of S2)_INTStep S40
The predetermined level t is determined by S41._INT1, T_INT2(T_INT1<
t_INT2), And when it is short it is bright and when it is long it is
Determined to be bright. Therefore, when it is bright,
Light emission, integration time t_IREDTo a shorter 250 μs (S4
4) When dark, t _IREDTo a longer 1000 μs (S4
2), at intermediate brightness, t_IREDTo 500 μs
(S43), each is set.

Thereafter, in step S45, integration without light emission is performed, and in step S47, integration with light emission is performed.
A repetition loop (S46, S48) for integration processing according to each set integration time is provided and executed, and reflection signal integration from which stationary light is removed is performed. Note that such an operation corresponds to step S8 in FIG. 4 of the first embodiment described above, and within a predetermined time (as if step S10 in FIG. 4 branches to NO), the integration is performed until the integration amount reaches a predetermined level. The process is repeated.

As described above, according to the second embodiment, the control of the active mode is optimized according to the brightness, and a highly accurate hybrid AF is achieved.

(Modifications) In addition, various modifications can be made to the above-described embodiment without departing from the gist of the present invention.

Although the embodiments have been described above, the present invention includes the following inventions. (1) A projection light source composed of an IRED and a strobe device for projecting distance-measuring light to an object in a pulsed manner, a sensor array for converting the distribution of light from the object to an electric signal, and a predetermined projection system. Extraction means (stationary light removal unit, pattern determination unit and A / D conversion unit) for extracting the reflected signal light component obtained by the sensor array when the light source is driven to emit light, and the output of the extraction means is pulsed. Integrating means (integrating circuit) for integrating in synchronism with (i), determining means (light quantity determining unit) for determining the brightness of the subject, and means for determining the pulse width of the pulsed light emission according to the output of the determining means. (Control unit).

(2) The determination means performs the distance measurement using light emission from the strobe device when the brightness is darker than a predetermined brightness, based on the output result of the sensor array when the distance measurement light is projected. If it is determined that the brightness is higher than a predetermined brightness, the distance measurement using the IRED is performed, and the distance measurement apparatus according to (1) can be provided. And it enables distance measurement with less power consumption.

(3) In the distance measurement using the above IRED, the distance measurement control is performed such that the number of times of light emission is large and the light emission integration time is short. Can be provided. And even if it is bright, S /
Enables improvement of N ratio. (4) The distance measurement device according to (2), wherein the control unit switches the integration time according to the brightness of the distance measurement target when performing distance measurement by the AF method of integrating up to a predetermined amount.

[0049]

As described above, according to the present invention, an appropriate reflection signal pattern can be obtained by the active mode under the optimum integration condition in which the switching noise and the random noise are prevented. However, correct triangulation can be performed.
Further, in a difficult scene, more accurate distance measurement can be performed in a light amount mode in which switching noise and random noise are prevented. Therefore, it is possible to provide a distance measuring device capable of performing accurate distance measurement even in dark and bright conditions, and to realize a distance measuring device having no distance measuring object that is difficult to perform.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a configuration of a distance measuring apparatus of the present invention.

FIG. 2A is a configuration diagram illustrating a partial configuration of the distance measuring device, and FIG. 2B is a graph illustrating a processing operation related to the portion;

FIG. 3A is a front view showing a light receiving element of the distance measuring apparatus, and FIGS. 3B to 3F are waveform graphs corresponding to the light receiving element.

FIG. 4 is a flowchart showing a distance measuring procedure of the distance measuring apparatus of the present invention.

FIG. 5 is a flowchart showing a part of an operation procedure of the actual distance measurement in the distance measurement procedure.

FIG. 6 is a timing chart showing a part of the processing operation of the actual distance measurement.

FIGS. 7A and 7B are timing charts showing an operation of switching from a dark state to a plurality of times of strobe light emission from a bright state.

FIG. 8 is a flowchart showing a countermeasure process for a noise error in the actual distance measurement.

FIG. 9 is an explanatory diagram showing a screen of a camera to which the present invention is applied and showing a positional relationship between a sensor array and a light projection pattern.

FIG. 10 is a block circuit diagram showing a stationary light removing circuit.

11A and 11B show a light emission operation in the distance measurement control of the present invention. FIG. 11A is a timing chart when a predetermined short light emission time is set, and FIG. 11B is a case where the light emission time is doubled. Timing chart.

FIG. 12 shows a signal light pattern reflected by a sensor;
FIG. 12A is a waveform diagram showing a reflected signal light pattern to be obtained, and FIG. 12B is a waveform diagram showing a reflected signal light pattern when the light emission integration time is shortened and the number of times of integration is increased.

FIG. 13 is a timing chart showing a relationship between a drive current for light emission and a light emission amount.

FIG. 14 is a flowchart showing a light emission time switching procedure of active mode AF in the IRED.

[Explanation of symbols]

1 ... CPU (arithmetic control means), 1a ... control unit,
1b: EEPROM, 2a, 2b: light receiving lens, 3a,
3b: sensor array, 4, 5: condenser lens, 4a: IR
ED, 4b: driver, 5a: strobe device (strobe light emitting means), 7: stationary light removing section (steady light removing means), 7a: transistor, 7b: capacitor, 7c
... Current detection circuit, 8 ... Release switch, 9 ... Focusing section (focusing means), 11 ... Pattern determining section (Pattern determining means), 12 ... Correlation computing section (Correlation computing means),
13: reliability determination unit (reliability determination unit), 14: light amount determination unit (light amount determination unit), 16: A / D conversion unit (A / D conversion unit), 16a, 16e: integration amplifier (integration unit),
16b, 16f: integrating capacitors, 16c, 16d, 1
6g: switch, 16h: difference amplifying unit (differential amplifying unit), 17: integral determining unit: comparator (integral determining unit). S1 to S29: Distance measuring procedure of the first embodiment, S8a
S8d: IRED-AF procedure of the first embodiment, S30
To S35: Light intensity AF procedure of the first embodiment, S40 to S4
8. IRED-AF procedure of the second embodiment.

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Claims (2)

[Claims] 1. A sensor array for converting the distribution of light incident from an object into an electric signal, a light source for projecting distance-measuring light to the object in a pulsed manner, and a light source for projecting the light source Extraction means for extracting a reflected signal light component obtained from the sensor array when driven, integration means for integrating the output of the extraction means in synchronization with the pulsed light emission, and brightness of the object. A distance measuring device comprising: a determination unit for determining; and a determination unit for determining a pulse width of the pulsed light emission according to an output of the determination unit. 2. The distance measuring apparatus according to claim 1, wherein the determining means determines the brightness based on an output result of the sensor array when the distance measuring light is not projected.