JPH08278125A - Distance measuring equipment - Google Patents

Abstract

PURPOSE: To provide distance measuring equipment capable of measuring a near distance and even a far distance accurately by arraying a plurality of rows of photosensors with the optical axes thereof aligned along the same direction and in such a state as separated from one another and arrayed on the same line. CONSTITUTION: A distance sensor 10 is formed so that photosensor arrays 1Ps to 3Ps having light receiving elements sufficiently smaller than an image size and arrayed at the imaging positions of imaging lenses 1Le to 3Le are arranged with optical axes kept in the same direction and in such a state as separated from one another and laid on the same line. Furthermore, the measurement start and ending operations of the sensor 10 are controlled with a measurement control section 6. Also, an image data memory section 5 saves data imaged on the arrays 1ps to 3Ps, and an image data selector section 8 selects and extracts two image data applicable to the calculation of a distance among the data on a plurality of the photosensor arrays 1ps to 3Ps. Then, a distance computing section 7 calculates a distance to a measurement object on the basis of the two selected image data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallax detection type distance measuring device for measuring a distance from an image position of an object captured by a geometrical optical system to the object.

[0002]

2. Description of the Related Art As a device for optically measuring a distance to an object, a distance measuring object such as a vehicle having optical axes arranged in parallel at a constant interval, as disclosed in JP-A-6-174845. A photosensor array such as a CCD in which light-receiving elements of a size sufficiently smaller than the size of the image is arranged at the imaging position of two lens systems with the same focal length to form the image of an object, and both optical axes The difference between the relative position of the image of the distance measurement object that appears corresponding to the distance between the object and the optical axis is detected, and based on the optical relational expression between the image of the object and the lens, the distance between the lens and the distance measurement object is determined. Practical use of a parallax detection type distance measuring device for calculating a distance, that is, a distance to a distance measuring object is performed.

First, the principle of distance measurement will be described with reference to FIG. 5 which illustrates an optical principle of distance measurement in a parallax detection type distance measuring device. Lens 1 in FIG.
Le and 2Le are lenses having the same focal length, and are arranged with their optical axes parallel to each other with a space b. The point E is the point of interest of the distance measurement target, and the images of the point E formed by the lenses 1Le and 2Le are formed at the positions H and J, respectively.

The relationship between the lens-object distance L and the lens-image distance s is established by the equation (1) regarding the lens formation based on the principle of geometrical optics.

[0005]

1 / s−1 / L = 1 / f (1) where f is the focal length of the lens, and in the optical system of the lens 2Le, iE is regarded as an object between the optical axis iI and the point E. Then, the image is formed on the IJ, and the following equation (2) is established due to the similar relationship established for the object and the image.

[0006]

## EQU00002 ## iE / L = IJ / s (2) Similarly, regarding the lens 1Le, when gE is regarded as an object, the image is formed on GH, and the following equation (3) is established due to the similarity relationship. To do.

[0007]

## EQU3 ## gE / L = GH / s (3) iE-gE = b by subtracting the equation (2) from the equation (3)
Using the above relation, and if IJ-GH, which is the relative deviation of the image position with respect to the optical axis in both optical systems, is set to Δx, formula (4) is derived.

[0008]

## EQU00004 ## b / L = .DELTA.x / s (4) However, .DELTA.x = IJ-GH On the other hand, since 1 / s in the equation (4) is obtained by the equation (1), this is substituted into the equation (4). Equation (5) is derived by rearranging.

[0009]

L = f (b / Δx−1) (5) In the above optical system, the relative deviation Δx of the image position with respect to the optical axis is usually very small compared to the interval b of the optical axis, and b Since / Δx >> 1, the equation (5) can be accurately approximated by the equation (6).

[0010]

L = f · b / Δx (6) In the parallax detection type distance measuring device according to the prior art, two pairs of tying optical systems each including a lens and a photosensor array are arranged with their optical axes separated from each other. The distance sensor is configured to detect the relative difference of the position of the image of the distance measurement target captured by each photosensor array with respect to the optical axis, and the calculation processing based on equation (6) is executed to measure the distance to the measurement target object. Are seeking.

Since the distance measurement principle of the parallax detection type distance measuring device complies with the equation (6), the measurement range and the measuring accuracy of the parallax detection type distance measuring device are the characteristics of the tying optical system constituting the distance sensor and its measurement. The following explanation will be restricted by the arrangement interval. First, restrictions on the measurement range will be described.
In FIG. 5A, the measuring object E is the lenses 1Le and 2
Angles θL and θ at which the object is seen from the lens as it approaches Le
R becomes large, and as a result, one of the image formation positions H and J of the object E exceeds the sensitive area of the photosensor arrays 1Ps and 2Ps, and measurement becomes impossible.

The values of the angles θR and θL at which the object is seen from the lens are equal maximum values when the object is on the midline of the optical axes of the two optical systems, as illustrated in FIG. The images are formed at equidistant positions in opposite directions with respect to the optical axis of each optical system, and therefore the relative deviation Δ of the image position is
x is twice the distance between the optical axis object images. When the object is on the middle line of the optical axes of the two optical systems and the value of the relative deviation Δx of the image position exceeds the sensitive area width 2W of the photosensor array, the imaged position of the object is outside the sensitive area of the photosensor array. It is impossible to measure distance. Therefore, the shortest measurable distance Lmi is the image position relative deviation Δx in the equation (6).
Is replaced by a sensitive area width of 2 W of the photo sensor array, and the following expression (7) is satisfied.

[0013]

## EQU00007 ## Lmi = f.b / 2W (7) The formula (7) is to reduce the shortest measurable distance Lmi,
It is shown that a distance sensor may be configured by using a photosensor array having a large sensitive area width 2W and a lens having a short focal length f and setting a small optical axis interval b of the two-connection optical system.

Next, the restriction on the measurement accuracy will be described.
Expression (6) is differentiated with respect to Δx, and again using Expression (6), Δ
Eliminating x gives equation (8).

[0015]

[Equation 8] dL = −L ² · dΔx / b · f (8) According to the equation (8), the resolution dL in the distance measurement is proportional to the square of the measurement distance L. The relative error dL / L when measuring the distance is the measurement distance L
It can be read that it deteriorates in proportion to. Thus, in order to improve the measurement accuracy, a photosensor array having a light receiving element of a minute size capable of detecting a slight change in the difference dΔx in the difference between the imaged positions and a lens having a large focal length f. It is shown that the distance sensor may be configured by setting the optical axis interval b of the two-conjunction optical system to be large by using.

As described above, the requirement to reduce the shortest measurable distance and the requirement to improve the measurement accuracy are contradictory to each other. Therefore, the conventional parallax-detecting distance measuring device has a size / size which is available at a reasonable price. By using a photosensor array with high resolution, the measurement distance range is divided according to the purpose of use, and the focal length f of the lens and the arrangement interval b of the tying optical system are arranged so that the measurement value can be obtained with appropriate accuracy in each measurement distance range division.
Is selected to integrally form a pair of two tying lenses and a photo sensor array to form a distance sensor module.

[0017]

DISCLOSURE OF THE INVENTION A parallax detection type distance measuring device based on the prior art is designed and configured to divide a measurement distance range and obtain a measured value with a corresponding accuracy in each measurement distance range division. Therefore, it is difficult to accurately measure a wide distance range with a single distance measuring device, and there is a problem that accuracy is remarkably reduced when measuring a long distance with a device capable of measuring a short distance.

The present invention is capable of measuring short distances, and
An object of the present invention is to provide a parallax detection type distance measuring device capable of measuring a long distance with good accuracy.

[0019]

In order to achieve the above object,
According to the present invention, three pairs of photosensor arrays are provided in which a parallax detection type distance measuring device is arranged at an image forming lens and a light receiving element having a size sufficiently smaller than the size of an image arranged at the image forming position of the image forming lens. A distance sensor in which the above plural pairs are aligned in the direction of the optical axis and spaced apart from each other, and the photosensor arrays are arranged on the same straight line, and the operation of starting and ending the measurement of this distance sensor is controlled. A control circuit unit, an image data storage unit that stores image data formed on a photo sensor array of a distance sensor, and two image data that are applied to distance calculation from image data of a plurality of photo sensor arrays. And an image data selecting unit for executing the calculation for calculating the distance from the two selected image data to the measurement object.

[0020]

The position information of the object image formed on the photosensor array is used as the arrangement order of the memory cells corresponding to the photosensor array in the image data storage unit, and the brightness information of the object image is used as the stored value of the memory cell. If the image data selection unit holds the same luminance distribution by checking the arrangement state of the luminance information, which is the stored value of the memory cell corresponding to each photosensor array of the image data storage unit, and obtains the same luminance distribution, Interpret and recognize the memory cell array order corresponding to the brightness distribution as the image position on each photosensor array, and from the recognized image position information, the pair of photosensor arrays that has the largest relative difference in image position. Is selected and extracted, and the distance calculation unit calculates the distance to the measurement object based on the image position information captured by the selected photosensor array pair.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a block configuration of an embodiment in which a distance sensor is constituted by three pairs of imaging lenses and a photosensor array according to the present invention, and FIG. 2 is a diagram explaining an optical principle. The present invention will be described with reference to these drawings. In the embodiment shown in FIG. 1, three pairs of an imaging lens Le and a photosensor array Ps in which light-receiving elements having a size sufficiently smaller than the size of an image arranged at a concatenation position of the imaging lens are arranged are respectively provided. The distance sensor 10 is constructed by arranging the photosensor arrays Ps on the same straight line with b1 and b2 at the distance between the optical axes.

Then, the measurement control unit 6 for controlling the measurement start / end operation of the distance sensor 10 is connected to each of the photosensor arrays 1Ps to 3Ps of the distance sensor 10 when the measurement control unit 6 sends a measurement end signal. An image data storage unit 5 for storing imaged image data, and an image data selection unit 8 for selectively extracting two image data items to be used for calculating a distance from the image data stored in the image data storage unit 5 are provided. The distance measuring device 20 is configured by the distance calculating unit 7 that executes the calculation for calculating the distance based on the two pieces of image data information and outputs the result.

In the distance measuring device 20 shown in FIG. 1, the measurement control unit 6 sends a command to start and end the measurement to the distance sensor 10 at a constant cycle, and when the command to end the measurement is issued, the photosensor arrays 1Ps to 3Ps. The value of the electric quantity determined by the amount of received light from the start to the end of the measurement held by each light receiving element is read out and transferred to the memory cell corresponding to the light receiving element of each photosensor array forming the image data storage unit 5.
As a result, the position information of the object image formed on the photosensor array Ps is stored as the arrangement order of the memory cells corresponding to the photosensor array of the image data storage unit 5, and the brightness information of the object image is stored in the memory cell. It will be retained as a value.

When the transfer processing of the image data detected by the photosensor array Ps by the measurement control section 6 to the image data storage section 5 is completed, the image data selection section 8 is set in each photosensor array of the image data storage section 5. When the array status of the brightness information, which is the stored value of the corresponding memory cell, is checked and an equivalent brightness distribution is obtained, it is interpreted as an image of the same object, and the memory cell array order corresponding to the brightness distribution is assigned to each photo sensor array. The image position is recognized as an image position on the upper side, and a pair of image position information that gives a more accurate result in the calculation of the distance based on the optical principle described below is selectively extracted from the recognized image position information to calculate the distance. Deliver to 7. And
The distance calculator 7 calculates and outputs the distance to the object to be measured based on the pair of image position information delivered from the image data selector 8.

Next, based on FIG. 2 which is an explanatory view of the optical principle, and also with reference to FIG. 5 which illustrates the measurement principle of the parallax detection type distance measuring device, the distance measuring device of the embodiment shown in FIG. The optical principle of is explained. In addition, in FIG.
The components of the distance sensor are given the prefixes 1 to 3, and the components having the same functions as those in FIG. 4 are denoted by the same symbols as those in FIG. 4, so detailed description thereof will be omitted.

When the object to be measured is at a sufficient distance from the distance measuring device 20, for example, at the position Ef in FIG.
An image of the object Ef to be measured is formed on any of the three photosensor arrays of 1 Ps to 3 Ps, and even if any two of the three photosensor arrays are selected, the image position on the photosensor array is selected. The value of the relative position difference Δx can be detected, and the value of the relative position difference Δx of this image is applied to the equation (6) to obtain the distance L to the object to be measured.

However, the resolution d in the distance measurement
As shown in the equation (8), L is improved in inverse proportion to the optical axis interval b of the two-concatenation optical system when the values of other optical element specifications are constant, so that in the example of FIG. By selecting the photosensor arrays 1Ps and 3Ps at both ends, the value of the distance b1 + b2 between the optical axes of both photosensor arrays and the value Δx of the difference between the relative positions of the image positions Hf and Jf on both photosensor arrays are expressed as Formula (6)
The results obtained by applying the values to b and Δx, respectively, are the highest resolution measurement values obtained by this measurement system.

On the other hand, when the object to be measured is located at a position close to the distance measuring device 20, for example, position En in FIG. 2, the object is out of the field of view for the image detection system including the tie lens 3Le and the photosensor array 3Ps. , The image can be obtained only in the image detection system with the prefixes 1 and 2, so the photo sensor array 1Ps
And 2Ps are selected to determine the value of the distance b1 between the optical axes of both photosensor arrays, and the image positions Hn and J on both photosensor arrays.
The value Δx of the difference between the relative positions of n and b in equation (6)
And Δx are applied to obtain the distance to the object En located at a short distance.

As described above, a pair of photosensor arrays that maximizes the relative difference Δx between the image positions captured by the photosensor array is selected in both high-precision and long-distance measurement. ing. That is, the image data selection unit 8 examines the image position information captured by each photosensor array, selects and extracts the pair of photosensor arrays having the maximum value of the relative difference Δx of the image positions, and the selected photosensor array pair is The captured image position information may be passed to the distance calculation unit 7.

By the way, as described in the section of the prior art,
Select the focal length f of the tie lens, the resolution and size of the photosensor array, and the tie arrangement b of the tie optical system so that the measured values can be obtained with appropriate accuracy in the measurement distance range classification that suits the purpose of use. A distance sensor module in which the image forming lens and the photo sensor array are integrally formed is prepared. FIG. 3 shows a block configuration of an embodiment in which a distance sensor is constructed by using two distance sensor modules. The present invention will be described.

In the embodiment shown in FIG. 3, two distance sensor modules 11 and 12 each consisting of a pair of imaging lenses and photosensor arrays whose optical axes are arranged at a constant interval b are arranged between the optical axes of both distance sensor modules. The distance D is arranged.
The photosensor arrays in the two distance sensor modules are usually arranged so as to be aligned. Then, a measurement control unit 6 that sends a command to start and end the measurement to both distance sensor modules 11 and 12 in a constant cycle, and an image data storage unit 5 that temporarily stores the image data detected by both distance sensor modules. An image data selection unit 8 for selecting and extracting image data most suitable for distance measurement from the image data stored in the image data storage unit 5 and an object to be measured based on the image data selected by the image data selection unit 8. The distance measuring unit 20 is configured by the distance calculating unit 7 which calculates the distance to the distance.

In the distance measuring device 20 shown in FIG. 3, the measurement control unit 6 sends a command to start and end measurement to the distance sensor modules 11 and 12 at a constant cycle, and when the command to end measurement is sent. Photo sensor array Ps in
The value of the electric quantity determined by the amount of received light from the start to the end of the measurement held by each light receiving element is read and transferred to the memory cell corresponding to the light receiving element of each photo sensor array forming the image data storage unit 5. As a result, the position information of the object image formed on the photo sensor array Ps of the distance sensor module is used as the arrangement order of the memory cells corresponding to the photo sensor array of the image data storage unit 5, and the brightness information of the object image is It will be held as the stored value of the memory cell.

When the transfer processing of the image data detected by the photosensor array Ps by the measurement control unit 6 to the image data storage unit 5 is completed, the image data selection unit 8 and the distance calculation are performed in the same manner as in the description based on FIG. The distance calculator 7 calculates the distance to the object to be measured based on the pair of image position information delivered from the image data selector 8 and outputs the calculated distance.

FIG. 4 is an explanatory diagram of the measurement principle of the distance measuring device having the configuration of FIG. 3 using two distance sensor modules. As shown in FIG. 4, the object to be measured is the distance measuring device 20. When it is at a position Ef sufficiently far from the photo sensor array 1 in the distance sensor modules 11 and 12.
An image of the object Ef to be measured is formed in any of Ps to 4Ps, and even if any two of the four photosensor arrays are selected, the difference Δ in the relative position of the image positions on the photosensor array is Δ.
The value of x can be detected, and the value of the difference Δx in the relative position of this image is applied to equation (6) to obtain the distance L to the object to be measured. The resolution dL in the distance measurement is shown in equation (8). As described above, when the values of other optical element specifications are constant, the values are improved in inverse proportion to the optical axis distance b of the two-piece optical system. Therefore, in the example of FIG. 4, the photosensor arrays 1Ps and 4Ps at both ends are improved. And the optical axis distance (D + b) of both distance sensor modules and the value Δx of the difference between the relative positions of the image positions Hf1 and Jf2 on both photosensor arrays are respectively expressed by b in equation (6). The result obtained by applying .DELTA.x to .DELTA.x is the highest resolution measurement value obtained by this measurement system.

On the other hand, when the object to be measured is at a position close to the distance measuring device 20, for example, En, the object En is out of the field of view with respect to the distance sensor module 11 and the photosensor array 3Ps in the distance sensor module 12. Since the image of the measurement target object En is imaged only on 4Ps, the image data selection unit 8 passes the image data captured by the distance sensor module 12 to the distance calculation unit 7 to obtain the distance to the measurement target object. .

[0036]

According to the present invention, three or more pairs of imaging lenses and photosensor arrays are arranged to form a distance sensor, and two image data to be applied to distance calculation are selected from image data of the photosensor array. In the parallax detection type distance measuring device that extracts and calculates the distance to the measurement object, when measuring the measurement object at a long distance, the image data captured by the pair of photosensor arrays with a disposition interval is selected. When measuring an object to be measured at a short distance, the image data captured by the pair of photosensor arrays with a short arrangement interval is selected and the distance is calculated by the distance calculation unit. It is possible to maintain accuracy, and it is possible to measure a wide range from short distance to long distance with high accuracy without leaving the visual field of the distance measuring device even for measuring objects at short distance. The effect of wear can be obtained. Then, in a distance measuring device in which two or more distance sensor modules each formed by integrally forming two lenses and a photosensor array are arranged with their optical axes separated from each other, and which are distance sensors. , The parallax detection type distance measurement that can measure a wide range from a short distance to a long distance with high accuracy because the selectable range of the distance between the photo sensor array pairs is significantly widened depending on the arrangement distance of the distance sensor module. The effect that the device can be realized without a large increase in cost is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram for explaining the principle of the distance measuring method according to the present invention.

FIG. 3 is a block diagram of another embodiment of the present invention.

FIG. 4 is a diagram for explaining the principle of the embodiment of FIG.

FIG. 5 is a diagram illustrating the principle of a parallax detection type distance measuring device.

[Explanation of symbols]

 1Le, 2Le, 3Le, 4Le Imager lens 1Ps, 2Ps, 3Ps, 4Ps Photo sensor array 5 Image data storage unit 6 Measurement control unit 7 Distance calculation unit 8 Image data selection unit

Claims (2)

[Claims] 1. A plurality of pairs of photosensor arrays, each of which is formed by arranging an image forming lens and a light receiving element having a size sufficiently smaller than the size of an image arranged at a concatenation position of the image forming lens,
A distance sensor in which the optical axes are separated from each other so that the directions of the optical axes coincide with each other, and the photosensor arrays are arranged on the same straight line; and a control circuit unit that controls the operation of starting and ending the measurement of the distance sensor. And an image data storage unit for storing image data formed on the photo sensor array of the distance sensor, and a pair of image data of two data used for distance calculation is selectively extracted from the image data of the plurality of photo sensor arrays. A distance measuring device comprising: an image data selection unit; and a distance calculation unit that executes a calculation for calculating a distance from a selected pair of image data to a measurement target. 2. A distance sensor comprising two lenses having the same focal length and arranged in parallel with each other with an optical axis at a fixed interval, and a size sufficiently small as compared with the size of an image arranged at the image forming position of each lens. And a plurality of distance sensor modules integrally formed with a light-receiving sensor array in which the light-receiving elements are arranged so that the optical axes of the distance sensor modules are separated from each other and the directions of the respective optical axes coincide with each other. The distance measuring device according to claim 1, wherein the arrays are arranged so as to be aligned on the same straight line.