JP2003344044A - Ranging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve decision accuracy in a decision across glass. <P>SOLUTION: When a ranging value is smaller than specific distance and the light reception output of a ranging apparatus is smaller than a specific value in the active type ranging apparatus, the presence or absence of spot lack in the light reception output is detected. In the absence of the spot lack, it is decided that photographing across grass is made. In the presence of spot lack, it is decided that a normal photographing environment is present. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a distance measuring device mounted on a camera or the like for optically measuring a distance to a distance measuring object.

[0002]

2. Description of the Related Art In a conventional distance measuring device, a spot light is projected onto an object to be measured, the reflected light of the projected spot light from the object to be measured is received, and the received light output serves as a principle of triangulation. An active distance measuring device for measuring a distance to an object to be measured based on the above is well known.

Also known is a phase difference detection type distance measuring device in which two lenses on the light receiving side and two light receiving elements are arranged in the longitudinal direction of the base line, and the distance to the distance measuring object is obtained from the correlation of the received light images obtained from the two lenses. Is.

In a camera equipped with such a distance measuring device, since the distance measuring device irradiates a spotlight on a distance measuring object as described above, a scene from the window of a car or an airplane (hereinafter referred to as a glass) is photographed. When taking a picture, the window glass may be measured instead of the object to be photographed, resulting in a defocused photograph.

In order to eliminate out-of-focus photographs when photographing through glass, Japanese Patent Laid-Open No. 9-229671 is disclosed, for example.

In Japanese Patent Laid-Open No. 9-229671, FIG.
As described in (1), the light projecting element 1 is pulse-projected through the light projecting lens 2 toward the object to be measured by the light projecting drive unit according to the command of the CPU 9. A part of the projected light flux is reflected by the glass 11 and is received by the light receiving elements 5 and 6 via the light receiving lenses 3 and 4, respectively. Further, the remaining light flux transmitted through the glass 11 is similarly received by the light receiving elements 5 and 6 via the light receiving lenses 3 and 4, respectively. If the object to be photographed is a long-distance landscape, the light receiving level of the light flux transmitted through the glass 11 is much smaller than that of the light flux reflected by the glass 11.

The signals received by the light receiving elements 5 and 6 are sent to the CPU 9
In response to the instruction, the received light signal 7 is processed into a value corresponding to the distance.

The received light output level from the received light signal processing unit 7 is compared with a predetermined signal amount by the signal amount determination unit 8.

As shown in the flowchart of FIG. 4, the distance measuring operation of the distance measuring device of FIG. 3 first performs active distance measuring in step 701. Next, the distance L to the object for distance measurement obtained from the received light signal processing unit is compared with a predetermined distance. If L is longer than the predetermined distance, it is unlikely that the glass 11 has been distance-measured, so the distance is determined in step 705. It is L, which is the result of distance measurement of information. On the other hand, when L is shorter than the predetermined distance, in step 703, the signal amount determination unit 8 compares the signal level of the light receiving element obtained from the light receiving signal processing unit 7 with the predetermined amount. As a result, when the signal level is higher than the predetermined amount, it is extremely likely that the distance measurement target is in a short distance without glass. Therefore, the distance information is measured as L in step 705, and the signal level is L. When the amount is less than the specified amount, glass 1
Since there is a high possibility that distance 1 has been measured, the distance information is set to infinity (step 704).

Here, the predetermined amount, which is the comparison target of the signal level of the light receiving element, is the normal distance measurement (such as glass) of the low reflection distance measurement target at the predetermined distance compared with the distance measurement value in step 702. It is smaller than the output of the light receiving element when there is no obstacle).

As described above, in Japanese Unexamined Patent Publication No. 9-22967, the glass is distance-measured when the signal amount is very small even though the distance is short from the distance measurement value and the light receiving level of the light receiving element. Deciding. This is said to be effective when the projected light beam diffusely reflected by the glass 11 is received by the light receiving element 5 or 6.

[0012]

DISCLOSURE OF THE INVENTION Now, with no glass window between the distance measuring device and the distance measuring object (described as a normal distance measuring environment), the entire distance of the spot light from the light projecting element hits the distance measuring object. In the meantime, that is, in the case of FIG. 5A, the light reception output shown in the lower part of the figure is obtained. At this time, JP-A-9-2296
According to the method disclosed in Japanese Patent Publication No. 7, even if the distance measurement value is shorter than the predetermined distance, the light receiving output is higher than the glass-through determination level which is the predetermined value. Is adopted.

However, in a normal distance measuring environment, FIG.
When a part of the spot light of the light projecting element hits the object to be measured and the rest falls through the background, the light reception output becomes smaller than the through glass determination level as shown in the lower part of the figure. As a result, according to the conventional method, if the distance measurement value at this time is closer than the predetermined distance, it is determined that the photographing is through the glass despite the normal distance measurement environment, and according to FIG. Since the distance information is an infinite distance, a defocused photograph will be provided.

Here, an image in which the reflected light from the object to be measured is formed on the light receiving element is expressed as a light receiving spot, and FIG.
The state of the image on the light receiving element obtained under the distance measuring condition as shown in (b) is referred to as spot defect.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to erroneously display glass even if a portion of light from a light-projecting element directed to an object for distance measurement as described above escapes to the background and spot spots occur. An object is to provide a distance measuring device that does not make a pass judgment.

In order to solve the above problems, the distance measuring apparatus of the present invention comprises a light projecting means for projecting a spot light onto a distance measuring object, a light receiving means for receiving a reflected light from the distance measuring object, and the light receiving means. Calculating means for calculating the distance to the object to be measured based on the output signal of the means, first comparing means for comparing the distance calculated by the calculating means with a predetermined distance, and the calculated distance is Second comparison means for comparing the output value of the light receiving means with a predetermined value when the distance is shorter than a predetermined distance, and reflected light from the distance measuring object when the output value of the light receiving means is smaller than the predetermined value. A detection means for detecting the width of the image when the image is formed on the light receiving means, and a correction means for correcting the calculated distance to a predetermined distance according to the detection result of the detection means. .

Further, the light receiving means of the distance measuring device is composed of a sensor array.

Further, the light receiving means of the distance measuring device is characterized by comprising a pair of optical lenses and a pair of sensor arrays corresponding to the respective optical lenses.

The sensor array serving as the light receiving means is a CCD.

Further, the sensor array serving as the light receiving means is a CMOS sensor.

(Operation) According to the first aspect, even when the distance measurement value obtained from the distance measuring device is closer than the predetermined distance and the output value of the light receiving means is smaller than the predetermined value, the light receiving spot of the light receiving means. The presence or absence of the spot defect of the light is detected, and when there is a defect in the light receiving spot, it is understood that only a part of the light from the light emitting element hits the distance measurement target. As described above, it is possible to provide accurate distance measurement information without erroneously determining that the image is captured through glass in the above state.

According to the second and fourth aspects, the light receiving means is constituted by a sensor array such as a CCD or CMOS sensor, and the light receiving spot of each sensor output of the sensor array is detected. Spot missing can be detected easily.

According to a third aspect, the light receiving means comprises:
Since it is composed of a pair of optical lenses and a pair of sensor arrays corresponding to each, it is possible to obtain an accurate distance measurement value even if the light receiving spot is chipped.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the distance measuring apparatus according to this embodiment.

In FIG. 1, reference numeral 1 is a light projecting element such as an IRED or an LED which serves as a light source for projecting spot light, and this element is pulse-lit by the control of the light projecting drive unit 10 and the CPU 9. Further, the light from the light projecting element 1 is projected through the light projecting lens 2 toward the object for distance measurement.

Reference numerals 3 and 4 denote light-receiving lenses, and the light-projecting element 1
The reflected light of the distance measurement target of the light projected from the distance measurement target to the distance measurement target is imaged on the light receiving elements 5 and 6, respectively.

Each of the light receiving elements 5 and 6 is composed of a sensor array, which is, for example, a CCD or a CMOS.
It may be a sensor. The outputs of these sensor arrays are output as a pair of light reception signals.

Reference numeral 7 is a light receiving signal processing unit for calculating a pair of light receiving signals from the light receiving elements 5 and 6 into a value according to the distance.

Reference numeral 8 is a signal amount determination unit for comparing the level of the received light signal from the received light signal processing unit 7 with a predetermined value.
Reference numeral 2 is also a spot defect determination unit for determining the presence or absence of a spot defect of the light reception signal from the light reception signal processing unit 7.

Reference numeral 9 is a CP for performing integrated control of the distance measuring operation.
U is a glass window 11 at the time of shooting through the window.

Next, the distance measuring operation of the present invention will be described with reference to the flowchart of FIG.

First, in step 201, active distance measurement is performed. In the case of the block configuration diagram of FIG. 1, the light projecting element 1 projects light toward the object to be measured, and the light receiving elements 5 and 6 respectively receive the light.
The distance to the object for distance measurement is obtained by detecting the phase difference between the pair of received light signals obtained from the light receiving element.

Since the operation of active distance measurement is a well-known technique, its detailed description will be omitted.

Next, the distance measurement value L obtained in step 201
Is compared with a predetermined distance, and if the distance is longer than the predetermined distance, it is determined that the distance measurement is in a normal distance measurement environment, or that the window glass 11 is not measured even when shooting through a window. The distance measurement value L is adopted as the distance information.

On the other hand, when the distance measurement value L is shorter than the predetermined distance, there is a possibility that the window glass is distance-measured by photographing through the window, so the next judgment is made in step 203. Step 20
In No. 3, the signal amount determination unit 8 compares the received light signal level with a predetermined amount. When the level of the received light signal is larger than the predetermined amount, the distance measurement value is a short distance and the received light signal is large. It is determined that the environment is the distance environment, and the distance measurement value L is adopted as the distance information in step 206.

On the other hand, when the received light signal level is smaller than the predetermined amount, the received light signal is small even though the distance measurement value is a short distance, so there is a possibility that the window glass 11 is measured in distance through the window. high. Therefore, in step 204, the following judgment is made.

In step 204, the spot missing determination section 12 determines whether or not the light receiving spot is missing.
As this determination method, for example, the determination can be made by checking how consecutive the outputs of a predetermined value or more are continuous at the output level of each sensor of the sensor array which is the light receiving element. If the continuity is smaller than a predetermined value, it means that the light receiving spot is missing. If the received light signal has a missing spot, the light projecting element 1
It is considered that the level of the received light signal has become low because only a part of the spot light from the above has been received and the rest of the spot light has passed through the background. The distance measurement value L is adopted as

On the other hand, when the light receiving spot has no spot missing, the level of the light receiving signal is low even though the entire spot light from the light projecting element 1 hits the object to be measured.
Moreover, since the distance measurement value L is a short distance, it is determined that the window glass 11 is distance-measured by photographing through the window, and in step 205, a predetermined distance A preset as distance information is adopted.

Although the distance information is set to the predetermined distance A in step 205, the passive distance measurement may be executed without projecting the light projecting element 1.

[0041]

As described above, according to the present invention,
It is possible to reliably determine whether the distance measuring environment is normal or through a window based on not only the distance measurement value obtained from the distance measuring device and the signal amount of the light receiving signal but also the presence or absence of spot missing of the light receiving spot. Since it becomes possible, erroneous distance measurement due to erroneous detection of through-window determination is eliminated, and a highly accurate distance measuring device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a distance measuring device according to the present invention.

FIG. 2 is a flowchart illustrating the operation of the distance measuring device according to the present invention.

FIG. 3 is a block diagram illustrating a distance measuring device according to a conventional example.

FIG. 4 is a flowchart illustrating an operation of a distance measuring device according to a conventional example.

FIG. 5 is a diagram showing an example of a positional relationship between a distance measurement target and spot light and a light reception output when a spot is missing.

[Explanation of symbols]

1 Light emitting element 2 Projection lens 3 Light-receiving lens 4 Light receiving lens 5 Light receiving element 6 Light receiving element 7 Received light signal processing unit 8 Signal determination section 9 CPU 10 Projection drive unit 11 glass windows 12 Spot missing part

Claims (5)

[Claims] 1. A light projecting means for projecting a spot light onto a distance measuring object, a light receiving means for receiving reflected light from the distance measuring object, and a light receiving means up to the distance measuring object based on an output signal of the light receiving means. Calculating means for calculating the distance, first comparing means for comparing the distance calculated by the calculating means with a predetermined distance, and when the calculated distance is shorter than the predetermined distance, When the output value of the light receiving means is smaller than the predetermined value, the width of the image when the reflected light from the distance measuring object is formed on the light receiving means is compared with the second comparing means for comparing the output value with the predetermined value. A distance measuring device comprising: a detecting means for detecting; and a correcting means for correcting the calculated distance to a predetermined distance according to the detection result of the detecting means. 2. The light receiving means according to claim 1, wherein the light receiving means is constituted by a sensor array. 3. The light receiving unit according to claim 1, wherein the light receiving unit includes a pair of optical lenses and a pair of sensor arrays corresponding to the optical lenses. 4. The sensor array according to claim 2, wherein the sensor array is a CCD. 5. The sensor array according to claim 2, wherein the sensor array is a CMOS sensor.