JPH09196665A - Distance measuring device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To enable distance measurement even in a situation where a phase difference cannot be detected because a distance measurement target is a short distance. SOLUTION: When the object to be measured is a short distance, the received light image is projected from the light receiving means, and when the phase difference cannot be detected, the output from the light receiving means 11, 12 is formed on the light receiving means. Arithmetic means 32, 33, for obtaining the position of the center of gravity of the imaged light receiving image and for obtaining the distance from the position of the center of gravity to the object to be measured
34 is provided.

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 which detects a phase difference by an output of a light receiving means and measures a distance to a distance measuring object.

[0002]

2. Description of the Related Art An active distance measuring apparatus receives reflected light of projected light by means of a semiconductor position detecting element (hereinafter referred to as PSD) or the like, and outputs a reflected light position on the PSD (reflected light By detecting the position of the center of gravity,
It is well known that the distance to the object to be measured is obtained.

Further, in the above-mentioned center-of-gravity position detection method, the distance is erroneously measured for a contrast subject (for example, a subject having a contrast in which the reflectance is high on the half side of the subject but low on the other side). It is also known that two light receiving elements such as CCDs are provided side by side, the reflected light of the projected light is received by these, and the distance to the object to be measured is obtained by the phase difference of the signal output of each light receiving element.

This example will be described with reference to FIGS.

FIG. 7 is a diagram for explaining the principle of an active type phase difference distance measuring device having two CCDs.

In FIG. 2, 11 is a first light receiving element CC.
D (L) and 12 are second light receiving elements CCD (R).
Reference numerals 13 and 14 denote light receiving lenses that are provided side by side with a fixed base length B. 16 is an IRED which is a light projecting element
And 17 is a projection lens, these IRED16
The light projecting lens 17 forms a light projecting means. 41
Is an object to be measured.

In this figure, the distance from the principal points of the light receiving lenses 13 and 14 to the CCDs 11 and 12 is f, and the distance from the principal points of the light receiving lenses 13 and 14 to the object 41 to be measured is H,
Let B be the distance between the principal points of the light-receiving lenses 13 and 14 (base line length), and K be the distance between the principal points of the light-projecting lens 17 and the light-receiving lens 13.

When the object 41 to be measured is at infinity,
If the reflected light returns and is condensed by the light-receiving lens 13 and is focused on the CCD 11, the reflected light from the distance measuring object 41 at the distance H from the center position of the reflected light is received. X is the amount of movement of the received image up to the center position of the reflected light when it is focused by
_{1 and} when the object 41 to be measured is at infinity, the reflected light is returned and is condensed by the light receiving lens 14, and the CCD 12
The reflected light from the distance measuring object 41 located at the distance H from the center position of the reflected light when it is imaged on the light receiving lens 1
Letting X ₂ be the amount of movement of the received light image up to the center position of the reflected light when it is focused by 4 and imaged on the CCD 12, the following relationship holds.

H = (B × f) / (x ₂ −x ₁ ) ... (1) Next, the CCD 11 and the CCD 12 in FIG. 7 will be described in detail with reference to FIG.

Here, each of the CCDs 11 and 12 is L1.
To L8 and R1 to R8, each of which has a pixel pitch of P. Further, the distance from the left end of the L1 pixel to the left end of the R1 pixel is set to the light receiving lenses 13 and 1 described above.
B is equal to the principal point interval of 4. Further, as shown in the figure, four consecutive pixels of both CCDs 11 and 12 are set as the windows of WL and WR, respectively, and the method conventionally used for phase difference detection (the windows of WL and WR are moved by 1 bit each). , The phase difference is obtained by taking the correlation), and the denominator (x ₂
-X ₁ ) can be obtained.

In FIGS. 9A to 9C, 51 (51)
Reference numerals a to 51c) are light-receiving images received through the light-receiving lens 13, and 52 (52a to 52c) are light-receiving images received through the light-receiving lens 14.

FIG. 9A shows a light-receiving image on the CCDs 11 and 12 when the object 41 to be measured is at a finite distance, and the C
These are pixel outputs of the CDs 11 and 12, respectively. in this case,
Both CCD 11 and CCD 12 output pixels, and the phase difference can be detected.

FIG. 9 (b) shows the received light images on the CCDs 11 and 12 when the object 41 to be measured is at a short distance, and the CCD 1
These are pixel outputs of 1 and 12, respectively. In this case, CCD
11 has a pixel output, but the light-receiving image 52b received through the light-receiving lens 14 is imaged outside the CCD 12, so there is no pixel output from the CCD 12. For this reason, it not can also be determined as seek by the phase difference detection of the (x ₂ -x _1).

FIG. 9 (c) shows a light-receiving image on the CCDs 11 and 12 when the object 41 to be measured is in close proximity, and the CCD 1
These are pixel outputs of 1 and 12, respectively. In this case, the light receiving images 51c, 5 received through the light receiving lenses 13, 14 are received.
2c both protrude from the CCDs 11 and 12, and there is no pixel output. That is, (x ₂
Even if _one tries to obtain -x ₁ ), it cannot be obtained.

Here, the movement amount of the received light image on the CCD 11 and the CCD 12 is different because the movement amount x ₁ on the CCD 11 is x ₁ = (K × f) / H The movement amount x ₂ on the CCD 12 is x ₂ = { This is because (K + B) × f} / H ₂ , and x ₂ ≧ x ₁ in the configuration of FIG. 7.

FIG. 10 is a block diagram showing a circuit configuration of a distance measuring device using the distance measuring system shown in FIG. 7 (FIGS. 8 and 9).

In FIG. 10, 21 is the CCD 11,
A signal amplifying means for amplifying the pixel output of 12 and an A / D conversion of the amplified CCD pixel output, and a CP to be described later.
A / D conversion means for inputting into the phase difference calculation means in U,
Reference numeral 23 denotes an IRED drive means for turning on and off the IRED 16, which is controlled by a CPU 31 described later. Reference numeral 31 is a CPU that controls each part and performs calculations. 3
Reference numeral 2 denotes a phase difference calculating means for calculating a correlation amount from the output A / D converted by the A / D converting means 22 and for calculating a phase difference amount, which is included in the CPU 31.

An actual distance measuring operation by the distance measuring device having the above structure will be described with reference to FIG.

First, step (denoted as "S" in the figure) 3
In 01, the IRED is driven through the IRED drive means 23.
Turn on 16. Then, in the next step 302, the amplified and A / D converted signal (A / D converted value) from the CCD (L) 11 is taken into the phase difference calculating means 32. Next, in step 303, this time CCD (R)
The amplified and A / D-converted signal (A / D conversion value) from 12 is taken into the phase difference calculating means 32. In the following step 304, CCD (L) 11 and CCD (R) 1
Based on the A / D converted value of 2, the phase difference calculating means 32 calculates the phase difference.

Next, in step 305, it is judged whether or not the phase difference is obtained. If the phase difference is obtained from the received light signal as shown in FIG. 9A, the process proceeds to step 307, and here, in step 304 above. The distance to the object 41 to be measured is calculated from the obtained phase difference value, and the process proceeds to step 308. On the other hand, in step 305, as shown in FIGS.
When the phase difference cannot be obtained because of the light receiving signal as described above, the process proceeds to step 306, in which the flag for distance measurement NG is set and the process proceeds to step 308.

Then, in step 308, the above I
The IRED 16 is turned off via the RED drive means 23, and a series of distance measuring operations are ended in the next step 309.

[0022]

According to the above conventional example,
In the method in which the reflected light of the projected light is received by two light receiving elements and the distance is measured by the phase difference of the signal output, when the distance measurement target is not a short distance, that is, the light receiving image as shown in FIG. When the object to be measured is a short distance or a close distance, that is, when the light receiving image and the light receiving signal are as shown in FIGS. 9B and 9C, the phase difference can be detected. The phase difference could not be detected, and as a result distance measurement became impossible.

(Object of the Invention) A first object of the present invention is to provide a distance measuring device capable of performing distance measurement even in a situation where a phase difference cannot be detected because the object to be measured is a short distance. To provide.

A second object of the present invention is to provide a distance measuring device which can be made more practical by setting the distance measuring value to a specified distance, whereas the conventional device cannot measure the distance. To do.

[0025]

In order to achieve the first object, the present invention according to claims 1 to 6 is a light projecting means for projecting signal light onto an object to be measured, and the light projecting means. The light receiving means for receiving the reflected light from the object to be measured, and the plurality of lenses for forming the image of the reflected light from the object to be measured on the light receiving means. Detect the phase difference,
In the distance measuring device for measuring the distance to the object to be measured, when the phase difference cannot be detected, the barycentric position of the light receiving image formed on the light receiving means is determined based on the output of the light receiving means. Provided with calculating means for obtaining and calculating the distance to the object to be measured,
When the object to be measured is in a short distance and the received light image is projected from the light receiving means and the phase difference cannot be detected, the center of gravity of the received light image formed on the light receiving means from the output of the light receiving means. The position is calculated, and the distance from the center of gravity position to the object to be measured is calculated.

In order to achieve the second object,
According to a fourth aspect of the present invention, there is provided a light projecting means for projecting signal light onto an object for distance measurement, a light receiving means for receiving light reflected by the object for distance measurement of the light projecting means, and the object for distance measurement. A plurality of lenses for forming an image of the reflected light on the light receiving means, the phase difference is detected by the output of the light receiving means, and the distance to the distance measuring object is measured. If it is not possible to find the position of the center of gravity of the light-receiving image formed on the light-receiving means (for example, when the light-receiving sensor output is small), the distance measurement is performed assuming that the distance measurement target does not return the reflected light at a long distance. The value is set to a specified distance (for example, infinity).

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram showing a circuit configuration of a distance measuring device according to a first embodiment of the present invention. The same parts as those in FIG. 10 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 1, reference numeral 33 is a barycentric position calculating means for obtaining the barycentric position of the received light image on the CCD (L) 11 based on the A / D converted value of the signal output of the CCD (L) 11.
Reference numeral 34 is a judging means for judging the signal levels of the CCD (L) 11 and the CCD (R) 12, both of which are the CPU 3
It is provided in 1.

Further, as is clear from FIG. 7 described above, CC
Combination of D (L) 11 and light receiving lens 13 and IRED1
In the combination of 6 and the projection lens 17, the relationship of H = (K × f) / x ₁ (2) holds.

FIG. 2 is a flow chart showing an actual distance measuring operation of the distance measuring device having the above-mentioned structure, which will be described below.

First, in step 101, IRED
The IRED 16 is turned on via the driving means 23. Then, in the next step 102, the amplified and A / D converted signal from the CCD (L) 11 (A / D converted value)
Are taken into the phase difference calculation means 32. Next, step 103
At this time, A from the CCD (R) 12 was amplified.
The / D converted signal (A / D converted value) is taken into the phase difference calculating means 32. In the following step 104, CC
Based on the A / D converted values of D (L) 11 and CCD (R) 12, the phase difference calculating means 32 calculates the phase difference.

Next, in step 105, it is judged whether or not the phase difference is found. If the phase difference is found from the received light signal as shown in FIG. 9A, the process proceeds to step 109, in which the above step 104 is carried out. The distance to the object 41 to be measured is calculated from the obtained phase difference value, and the process proceeds to step 111.

On the other hand, in step 105, as shown in FIG.
If the phase difference cannot be obtained because of the received light signals as shown in (b) and (c), the process proceeds to step 106 and the CCD
The center of gravity of the received light image on the CCD (L) 11 is obtained based on the A / D converted value of (L) 11. The center of gravity of the light-receiving image on the CCD may be determined by using the pixel at the peak of the pixel signal, or by interpolating the pixels from the tilt angle of the image and calculating more finely than the pixel pitch.

Then, in step 107, the CCD
(L) It is determined whether the signal level of any pixel of 11 is higher than a predetermined value, and if the level of the signal as shown in FIG. Then, the distance is calculated based on the position of the center of gravity of the CCD (L) 11 obtained in step 106, and the process proceeds to step 111.

Further, in step 107 described above, FIG.
If the signal level of any pixel of the CCD (L) 11 is smaller than a predetermined value with such a signal, it is determined that the reliability of the calculation of the center of gravity is low, or the reflected light does not return at a long distance, and the process proceeds to step 110. Here, the distance measurement value is set as the designated distance (for example, infinity) and the process proceeds to step 111.

Then, in step 111, the above I
The IRED 16 is turned off via the RED drive means 23, and a series of distance measuring operations are ended in the next step 112.

(Second Embodiment) FIG. 3 is a block diagram showing a circuit configuration of a distance measuring apparatus according to a second embodiment of the present invention, and the same portions as those in FIG. 10 and FIG. The description is omitted.

In FIG. 3, reference numeral 19 denotes a CCD which is a light receiving element. The difference from FIG. 1 is that one of the two CCDs (CCD (L) 11, CCD (R) 12) is provided. It was connected to.

FIG. 4 is a diagram for explaining the principle of distance measurement in the second embodiment, and the difference from FIG. 10 is that 19 CCDs are provided as in FIG. is there. The other configurations and arrangements are the same as those in FIG.

Further, in FIG. 4, it is clear that the combination of the CCD 19 and the light receiving lens 13 and the combination of the IRED 16 and the light projecting lens 17 have the relationship of H = (K × f) / x ₁ .

FIGS. 5A and 5B are diagrams showing the details of the CCD 19 in FIGS. 3 and 4, and this CCD 19 is shown.
The size of one pixel of the CCD (L) 11 shown in FIG.
The size is the same as that of one pixel of the CD (R) 12. Of course,
The pitch of the pixels S1 to S20 that are continuously arranged in the CCD 19 is the same as that of the CCD (L) 11 and the CCD (R) 12 of FIG.

Further, from the pixel S1 to the pixel S2 of the CCD 19
The dimension up to 2 is the same as the dimension from the pixel L1 of the CCD (L) 11 to the pixel R8 of the CCD (R) 12 in FIG. That is, the CCD in FIGS. 5A and 5B
19 is compared with the two CCDs in FIG.
The pixels S1 to S8 in (a) and (b) are the pixels L1 to L in FIG.
8, the pixels S9 to S12 in FIGS. 5A and 5B are located between L8 and R8 in FIG. 8 and the pixels S13 to S12 in FIGS.
It is assumed that S20 has a position (dimension) relationship corresponding to R1 to R8 in FIG.

FIG. 5A shows a light-receiving image on the CCD 19 when the object to be measured is at a relatively long distance and the pixel output at that time.

In this case, the continuous arbitrary pixels on the right side of the S1 pixel of the CCD 19 (for example, 4 pixels of S1 to S4) are WL, and the continuous arbitrary pixels on the right side of the pixel S13 (for example, 4 pixels of S13 to S16). By setting the window as a WR and detecting the phase difference, it is possible to measure the distance as in the conventional example described above.

FIG. 5 (b) shows the light-receiving image on the CCD 19 when the object to be measured is in the vicinity and the pixel output at that time.

In this case, the light-receiving image formed through the light-receiving lens 13 is on the CCD 19, but the light-receiving image formed through the light-receiving lens 14 is out of the CCD 19. Even if the phase difference detection described in FIG. 5A is performed in such a state, the phase difference cannot be detected. However, FIG.
As described above, the combination of the CCD 19 and the light receiving lens 13 and the combination of the IRED 16 and the light projecting lens 17
It is possible to measure the distance by obtaining the center of gravity of the received light image on 19.

It should be noted here that the first embodiment of the above-mentioned embodiment is to be noted.
In the case of FIG. 9C described in the above embodiment, it is impossible to measure the distance, but in this embodiment, it is possible to measure the distance even when the object to be measured is at the same distance.

The distance measuring operation at this time will be described with reference to the flowchart of FIG.

First, in step 201, IRED
The IRED 16 is turned on via the driving means 23. Then, in the next step 202, the amplified and A / D converted signal (A / D converted value) from the CCD 19 is fetched into the phase difference calculating means 32. In the following step 203, the initial position of the window for detecting the phase difference is set, and in the following step 204, the phase difference calculating means 32 obtains the phase difference based on the (L) window and the (R) window.

Next, in step 205, it is judged whether or not the phase difference is obtained, and if the phase difference is obtained with the received light signal as shown in FIG. 5A, the process proceeds to step 209, and here, in step 204 above. The distance to the object to be measured is calculated from the obtained phase difference value, and the process proceeds to step 211.

On the other hand, in the above step 205, FIG.
When the phase difference cannot be obtained because the light receiving signal is as shown in step 206, the process proceeds to step 206 and A / A of all pixels of the CCD 19
The center of gravity of the received light image on the CCD 19 is obtained based on the D conversion value. As described above, the center of gravity of the light-receiving image on the CCD 19 may be determined by using the pixel at the peak of the pixel signal or by interpolating the pixels from the tilt angle of the image and finely calculating the pixel pitch.

Then, in step 207, the CCD 1
It is determined whether or not the signal level of any of the pixels 9 is higher than a predetermined value, and if the signal level as shown in FIG.
8, the CC obtained in step 206 above
The distance is calculated based on the position of the center of gravity of D19, and step 211
Proceed to.

In step 207, if the signal level of any pixel of the CCD 19 is smaller than the predetermined value due to a signal at infinity or the like, the reliability of calculation of the center of gravity is low, or reflected light is returned at a long distance. Step 21
The process proceeds to 0, where the distance measurement value is set to the designated distance (for example, infinity) and the process proceeds to step 111.

Then, in step 211, the above I
The IRED 16 is turned off via the RED drive means 23, and a series of distance measuring operations are ended in the next step 212.

According to each of the above embodiments, the CCD (1
If the phase difference cannot be detected from the output of 1, 12 or 19), the light receiving image position is detected by obtaining the barycentric position using the image from one light receiving lens, and Since the distance is measured, the distance can be measured even if the object to be measured is in a short distance and the phase difference cannot be detected.

If it is not possible to obtain the barycentric position (for example, if the CCD output is small), it is assumed that the object to be measured is a long distance and the reflected light does not return. Since the distance is set to infinity in each of the embodiments, it is possible to provide a more practical distance measuring device even when the conventional distance measuring is impossible.

(Correspondence between Invention and Embodiment) In each of the above embodiments, the IRED 16 corresponds to the light projecting means of the present invention, and the CCD (L) 11, CCD (R) 12 and CCD 1 are provided.
Reference numeral 9 corresponds to the light receiving means of the present invention, and the phase difference detecting means 32, the center of gravity position calculating means 33 and the signal output determining means 34 in the CPU 31 correspond to the calculating means of the present invention.

The above is the correspondence relationship between each configuration of the embodiments and each configuration of the present invention, but the present invention is not limited to the configurations of these embodiments, and the functions shown in the claims,
Needless to say, any configuration may be used as long as the functions of the embodiment can be achieved.

(Modification) The present invention can be applied to a distance measuring device having a plurality of light projecting elements and performing multi-point distance measuring. Further, the present invention can also be applied to a distance measuring device using a passive type auxiliary light.

[0061]

As described above, according to the present invention,
When the object to be measured is in a short distance and the received light image is projected from the light receiving means and the phase difference cannot be detected, the center of gravity of the received light image formed on the light receiving means from the output of the light receiving means. The position is calculated, and the distance from the center of gravity position to the object to be measured is calculated.

Therefore, even if the phase difference cannot be detected because the object to be measured is a short distance, the distance can be measured.

Further, according to the present invention, when it is impossible to obtain the barycentric position of the received light image formed on the light receiving means (for example, when the light receiving sensor output is small), the object to be measured is at a long distance. The distance measurement value is set to a specified distance (for example, infinity), assuming that the reflected light does not return.

Therefore, while the distance measurement cannot be performed in the conventional apparatus, the distance measurement value can be set to the designated distance to provide a more practical distance measurement apparatus.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a series of operations of the distance measuring device of FIG.

FIG. 3 is a block diagram showing a circuit configuration of a distance measuring device according to a second embodiment of the invention.

FIG. 4 is a diagram for explaining a distance measuring principle of the distance measuring device in FIG.

5 is a diagram showing a light-receiving image formed on the CCD of FIG. 3 when the object to be measured is located at different distances, and its pixel output.

FIG. 6 is a flowchart showing a series of operations of the distance measuring device of FIG.

FIG. 7 is a diagram for explaining the principle of a general active type phase difference distance measuring apparatus.

FIG. 8 is a diagram for explaining each CCD in FIG. 7.

9 is a diagram showing a light-receiving image formed on each CCD in FIG. 8 and a pixel output thereof when the object to be measured is located at different distances.

10 is a block diagram showing a circuit configuration of a distance measuring device using the distance measuring system shown in FIG.

11 is a flowchart showing a series of operations of the distance measuring device in FIG.

[Explanation of symbols]

 11, 12 CCD 13, 14 Light receiving lens 16 IRED 19 CCD 31 CPU 32 Phase difference calculation means 33 Center of gravity position calculation means 34 Signal output determination means

Claims (6)

[Claims] 1. A light projecting means for projecting light onto an object to be measured,
The light receiving means is provided with a light receiving means for receiving the reflected light of the distance measuring object of the light projecting means, and a plurality of lenses for forming an image of the reflected light of the distance measuring object on the light receiving means. In the distance measuring device that detects the phase difference based on the output of the above, and the distance to the object to be measured is not detected, the phase difference is detected on the light receiving means based on the output of the light receiving means. A distance measuring device comprising a calculation means for obtaining a barycentric position of an imaged light receiving image and calculating a distance to a distance measuring object. 2. The distance measuring device according to claim 1, wherein the light receiving unit includes a plurality of photoelectric conversion elements arranged in a line. 3. The distance measuring device according to claim 2, wherein the light receiving means is a CCD. 4. The distance measurement value is set to a specified distance when the barycentric position of the received light image formed on the light receiving means cannot be obtained. Ranging device. 5. The distance measuring device according to claim 4, wherein the designated distance is infinity. 6. The light projecting means emits auxiliary light for illuminating a distance measurement target.
The distance measuring device as described.