JP2002048533A - Distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately find a distance upto an object even when intensity of extraneous light (background light) such as sunlight is high, and to reduce a storage capacity and a computing time. SOLUTION: In this distance measuring device provided with a projector 10 for projecting emitting light front wards, and a photocell array 30 arranged to be separated from the projector 10 by a prescribed distance along a vertical direction with respect to an emitting direction, a beam of the emitted light is formed to be thin in a direction connecting the projector 10 witch the array 30, the array 30 detects reflected light in each of plural areas 301, 302, 302, 304 arrayed one-dimensionally, and a range of the distance upto the body (object) is measured by determining that the reflected light gets incident into any area of the plural areas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical distance measuring device, and more particularly to a distance measuring device for measuring an approximate distance from a measuring device to an obstacle based on the principle of triangulation.

[0002]

2. Description of the Related Art Conventionally, there are various non-contact distance measuring methods, one of which is disclosed in JP-A-11-160.
As shown in Japanese Patent Publication No. 050, an image of the slit light illuminated on the target object is taken, and a distance between each point on the slit light which is imaged using the triangulation method from the camera and the position where the slit light is applied is calculated. There is a method of measuring a distance to an object.

As shown in FIG. 7, a distance measuring method based on a general principle of triangulation irradiates a measuring object 21 with a spot-like or slit-like light from a light emitting element 11 through a light projecting lens 12 as shown in FIG. Then, the pattern light reflected by the object 21 is condensed on the image sensor 31 arranged at a position BL away from the light source in a direction perpendicular to the direction of the object, and the condensed position and intensity distribution Is a method of calculating the distance L to the object from the distance. In general, a CCD (charge coupled device) or a PSD is used as the imaging device.

In a three-dimensional shape measuring apparatus disclosed in Japanese Patent Application Laid-Open No. 11-160050, a two-dimensional pixel matrix is formed by arranging a plurality of line CCDs in parallel as shown in FIG.

[0005] Each line CCD shown in FIG.
The luminance value of each pixel of the horizontal scanning line read from is temporarily stored in an image memory or the like, and the luminance value of each pixel is compared with each other to determine a pixel having the maximum luminance value. The distance to the object has been calculated based on the optical system parameters of the light receiver.

[0006]

Generally, in order to image or receive the illuminated pattern light under sunlight, it is conceivable to increase the irradiation intensity and separate the disturbance light and the irradiation light. However, it is not realistic to irradiate light having an intensity that is not buried in sunlight.

Therefore, in order to separate the sunlight from the irradiation light, a method such as modulation of the irradiation light or synchronous detection is generally used, so that light such as sunlight has a small level fluctuation. (DC light) and relatively low-frequency disturbance light,
A method of separating the irradiation light is used.

However, Japanese Patent Application Laid-Open No. H11-160050
In the distance measuring device disclosed in Japanese Patent Application Laid-Open Publication No. H11-209, an image pickup device in which line CCDs are two-dimensionally arranged is used as an image pickup device. If the background light is strong like sunlight due to the detection, the irradiation light is buried in the sunlight and cannot be detected. Also, CCD
However, there is a problem that high-speed modulation of the light source intensity for improving the S / N ratio and synchronous detection of the output of the light receiving element cannot be performed due to the limitation due to the read speed.

In addition, the conventional optical distance measuring device temporarily stores the luminance values of a large number of pixels read from the image pickup device in an image memory or the like in order to find a pixel position having the maximum luminance.
Since the calculation for searching for the maximum luminance is performed from these luminance values, there is a problem that the calculation time for obtaining the distance requires much time.

In view of the above problems, it is an object of the present invention to provide a distance measuring device capable of reducing the memory capacity for temporarily storing a luminance value and shortening the calculation time for obtaining a distance.

Another object of the present invention is to provide a distance measuring device capable of accurately measuring the distance to an object even when the intensity of extraneous light (background light) such as sunlight is high.

[0012]

According to a first aspect of the present invention, there is provided a light projecting means for projecting irradiation light in a first direction, and a first direction from the light projecting means. And a light receiving means for receiving reflected light reflected by an object in the predetermined direction, the light receiving means being disposed at a predetermined distance in a predetermined second direction that is perpendicular to the object. The range of the distance to the object is measured by detecting reflected light for each of the plurality of regions arranged in the second direction and determining which of the plurality of regions the reflected light has entered. That is the gist.

According to a second aspect of the present invention, there is provided a distance measuring apparatus, wherein the irradiation light is a spot light or a slit light.

According to a third aspect of the present invention, in the distance measuring apparatus according to the first or second aspect, a unique binary code is assigned to each of the plurality of regions of the light receiving means. The light emitting means emits light at a plurality of light emission timings corresponding to the number of digits of the binary code, and each area of the light receiving means reflects at a timing at which each digit of the assigned binary code is "1". The gist of the present invention is to determine whether light is incident or not and calculate the logical sum of the determination result for each area to obtain a binary code time-series signal indicating the area where the reflected light is incident.

According to a fourth aspect of the present invention, there is provided a distance measuring apparatus according to any one of the first to third aspects, wherein the light projecting means modulates the intensity of irradiation light, The gist of the light receiving means is to detect an intensity signal of the reflected light and determine in which region the reflected light has entered.

According to a fifth aspect of the present invention, there is provided a distance measuring apparatus according to any one of the first to fourth aspects, wherein each of the plurality of regions arranged in the second direction is provided. The gist is that the length in the second direction is optimized to be unequal according to the measurement purpose.

According to a sixth aspect of the present invention, there is provided a distance measuring apparatus according to any one of the first to fifth aspects, wherein the first and second directions are perpendicular to each other. A plurality of said light receiving means are arranged in three directions,
The gist of the present invention is to detect the shape of an object or a plurality of objects.

[0018]

According to the first aspect of the invention, there is provided a light projecting means for projecting irradiation light in a first direction, and a predetermined light projecting means which is perpendicular to the first direction from the light projecting means. And a light receiving unit that receives the reflected light reflected by the object in the predetermined direction, the light receiving unit being arranged in the second direction. The reflected light is detected for each of the plurality of regions, and by determining which of the plurality of regions the reflected light has entered,
Since the range of the distance to the object is measured, it is not necessary to compare the luminance values of a large number of pixels to determine the pixel having the maximum luminance as in the related art, and the calculation time for obtaining the distance is significantly reduced. There is an effect that can be.

Also, instead of comparing the luminance values of a large number of pixels, it is determined which area of the light receiving means the reflected light has entered. Therefore, a memory for storing the luminance values of a large number of pixels. The capacity can be reduced.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, the irradiation light is spot light,
Alternatively, since the slit light is used, the spot light emitted from the laser diode or the like can be used as it is, or various conventional lamp lights can be used as the irradiation light source of the present invention through the slit.

According to the third aspect of the invention, in addition to the effects of the first or second aspect, a unique binary code is assigned to each of the plurality of areas of the light receiving means, and the light projecting means is provided. Emits light at a plurality of light emission timings corresponding to the number of digits of the binary code, and reflected light enters each area of the light receiving means at a timing when each digit of the assigned binary code is "1". It is determined whether the reflected light is incident or not, and the logical sum of the determination result for each area is calculated to obtain a time series of binary codes indicating the area where the reflected light is incident. Thus, a binary code string indicating the range of the distance to the object can be obtained.

According to the fourth aspect of the present invention, in addition to the effects of the first to third aspects, the light projecting means modulates the intensity of the irradiation light, and the light receiving means modulates the intensity of the reflected light. Since the signal is detected to determine in which area the reflected light is incident, even when the background illuminance around the daytime is high, the background light and the reflected light from the object can be easily separated. And highly accurate distance measurement can be performed.

According to the fifth aspect of the present invention, in addition to the effects of the first to fourth aspects, the length of the plurality of regions arranged in the second direction in the second direction can be increased. Since the length is optimized to be unequal length according to the measurement purpose, the resolution of the measurement distance can be easily changed.

According to the sixth aspect of the invention, in addition to the effects of the first to fifth aspects of the present invention, a plurality of the plurality of the first and second directions are perpendicular to the third direction. Since the light receiving means is arranged to detect the shape of the object or a plurality of objects, the shape of the object can be detected in addition to the distance to the object.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the relationship between the light receiving element array and the distance detection area, which is the basis of the present invention, will be described with reference to FIG. The light receiving element array 700 includes, for example, photodetectors (hereinafter abbreviated as PDs) 701 to 70 such as a plurality of phototransistors and photodiodes.
3 are arranged in a one-dimensional array, and each PD has a light receiving lens 70.
4 is set so as to detect only reflected light from an area defined in advance by the optical system including the optical system 4.

In FIG. 5, the light emitted from the light projector 705 is reflected by the area 1 and the reflected light is reflected by the light receiving lens 704.
And the reflected light from the area 2 is P
At D702, the reflected light from the area 3 is imaged at the PD 703, respectively.

As described above, since there is a one-to-one correspondence between the area where the object that reflects the irradiation light emitted from the light projector and the element where the reflected light is imaged by the light receiving lens has a one-to-one correspondence.
Depending on whether D has detected the reflected light, it is possible to know the area where the object that reflects the reflected light exists.

According to the present invention, based on this principle, an area where an object exists can be obtained by encoding the area where the object exists from the detection signal of each PD. That is, the area where the object exists can be uniquely identified by time-series coding of the detection signal. It can be described, which makes it unnecessary to calculate the distance at the subsequent stage of the PD.

Next, the time-series coding of the detection signal, which is a special feature, will be described with reference to the timing chart of FIG.

From the light emitter 705, time t1, t2,.
Irradiate spot light or slit light in a predetermined direction in the order of. At this time, at the timing of t1, the PD 701
And 703 shutters open, that is, PD70
Detection is performed on the 1,703 detection signals. Then t2
The shutters of the PDs 702 and 703 are opened at the timing of.

Here, the output of the light receiving element array 700 is defined as follows. “The light receiving element array 700 is
If at least one of 701 to 703 detects reflected light, 1 is output, and otherwise, 0 is output. " That is, at the timing t1, the output of the PD array 700 becomes 1 when one of the PDs 701 and 703 detects the reflected light, and at the timing t2, the reflected light is detected by either of the PDs 702 and 703. The output is 1. Otherwise, 0 is output.

When the object that reflects the reflected light is in the area 1, the light receiving element array 700 detects the reflected light only at the timing of t1. That is, the PD monitoring the area 1
Only 701 receives the reflected light. Similarly, when the object is in the area 2, the reflected light is detected only at the timing of t2,
When the object is in the area 3, reflected light is detected at both timings t1 and t2.

Now, let the code lengths of the time series coding be t1, t
2, the light receiving element array 700 at t1
Is the least significant bit, the light receiving element array 7 at t2
00 as the most significant bit, the light receiving element array 700
Is f (t2, t1), f (t2, t1) = 01 when an object exists in the area 1, f (t2, t1) = 10 when an object exists in the area 2, and area 3 When an object exists, f (t2, t1) = 11, and the output of the light receiving element array 700 indicates the area where the object exists in a time series of 2
It will be described in hexadecimal.

As described above, by setting the detection timing in accordance with the area to be monitored, the area where the object exists can be uniquely determined without calculation.
The memory and the operation device can be simplified, and the operation time can be reduced, so that the circuit scale can be reduced and the system cost can be suppressed.

Next, the principle of arranging a plurality of one-dimensional light receiving element arrays in parallel and identifying irregularities and multi-targets will be described with reference to FIG. FIG. 6 is a top view showing a state where the light receiving element array 710 is arranged in parallel with the light receiving element array 700 of FIG. Thus, by arranging a plurality of one-dimensional arrays in parallel, not only identification in the z direction (irradiation direction of the light emitting element) but also x direction (the width direction of the vehicle)
Can be identified. Therefore, by arranging a plurality of one-dimensional arrays in parallel, it is possible to identify unevenness of an object and a multi-target.

[Explanation of Embodiment] Next, referring to the drawings,
An embodiment of the present invention will be described in detail. FIG. 1 is a system configuration diagram showing a configuration of an embodiment of a distance measuring device according to the present invention.

In FIG. 1, the distance measuring device includes an object 2
1 is a light projector 1 for irradiating irradiation light having a thin light beam in the vertical direction in the figure, such as spot light or slit light, toward 1
0, a light receiving lens 32, a light receiving element array 30, a signal processing circuit 33, a timing generation circuit 34, and an OR circuit 35.

The light projector 10 includes a light emitting element 11 using a discharge lamp, a light emitting diode, a laser diode, or the like, a light emitting lens 12, and a driving circuit 13 for driving the light emitting element 11.
It is composed of

The spot light emitted from the light projector 10 toward the object 21 in the front (to the right in the figure) is light having an irradiation area formed in a dot shape, and the slit light is emitted from the light projecting lens 1.
The light is formed in a narrow slit shape so that the light flux does not spread in the direction from 2 to the light receiving lens 32.

The light-receiving element array 30 includes a plurality of (four in the example of FIG. 1) light-receiving elements 301, one-dimensionally in a direction perpendicular to the direction in which the projector 10 irradiates the object 21 with irradiation light. This is a light receiving element array in which the light receiving region is divided into a plurality of regions by arranging 302, 303, and 304.

The signal processing circuit 33 includes the light receiving elements 301 and 3
A signal processing circuit that processes output signals from the light-receiving elements 02, 303, and 304 and outputs a detection signal from the light-receiving element on which the reflected light is incident.
Coupling capacitor 332 for removing DC signal components
And a comparator 333 that compares the reference voltage with the detection signal;
An AND gate 334 that opens a gate at the detection timing of each light receiving element and an integrator 335 that integrates a signal during the detection timing are provided.

The timing generation circuit 34 includes a light emission command, which is a light emission timing signal of the light emitting element 11, and light receiving elements 301, 302, 30 as described later with reference to FIG.
3,304 detection timing signals are generated, and the AND gate 334 is controlled by the detection timing signals.

The OR circuit 35 is a circuit for calculating the OR of the output of the integrator 335 for each light receiving element.
It outputs a binary code time series signal indicating which light receiving element the reflected light from 1 has entered, in other words, which area of the light receiving means the reflected light has entered.

Next, the function of the entire system will be described with reference to FIG. Irradiation light such as slit light or spot light emitted from the light projector 10 forms an optical image on an object 21 on which an object exists within a predetermined area irradiated with the light, and forms the light image on the object 21. The light image thus formed forms a light receiving image on the one-dimensional light receiving element array 30 via the light receiving lens 32. Each light receiving element 301, 302, 303, 304 constituting each light receiving area of the light receiving element array 30 generates an output current according to the amount of received light.

A signal processing circuit 33 is connected to the subsequent stage of the light receiving element array 30 to detect which light receiving element has received the reflected light from the object 21, and the OR circuit 35 receives the reflected light. A time series signal of a binary code for identifying the light receiving element is output.

The distance between the binary code and the distance measuring device to the object 21 is determined in advance by the distance between the centers of the light projecting lens 12 and the light receiving lens 32, the distance between the light receiving lens 32 and the light receiving element array 30, Correspondence is required by the optical parameters of the lens system.

FIG. 2A shows the timing of the light emission command performed by the timing generation circuit 34, FIGS. 2B to 2E show the detection timing of each light receiving element, and FIG. 4 shows an example of the output timing. Here, for the sake of simplicity, the light receiving array 30 has the light receiving elements 301, 302, 30
The case where the number is composed of four of 3, 304 will be described.

Here, each light receiving element 301, 302, 30
3, 304 are assigned numbers 1, 2, 3, and 4, respectively, and the corresponding binary codes (001), (010),
(011) and (100) are assigned.

The detection timing input to the AND gate corresponding to each light receiving element is a timing at which the digit of the binary code takes a value of "1". That is, the timing of the light receiving element 301 is t1, the timing of the light receiving element 302 is t2, the timing of the light receiving element 303 is t1 and t2, and the timing of the light receiving element 304 is t3.

The drive circuit 13 of the light emitting element 11 receives the light emission command from the timing generation circuit 34, and drives the light emitting element 11 to output high-speed modulated irradiation light during a predetermined period. The light receiving elements 301 to 304 detect the detection signals at the timings shown in FIGS. 2B to 2E, respectively. The signal processing circuit 33 outputs 1 if the light receiving element detects reflected light. Otherwise, 0 is output corresponding to the output of each light receiving element. The OR circuit 35 performs an OR operation on the output values of the respective light receiving elements of the signal processing circuit 33.

Here, each light receiving element 301, 302, 30
3, 304 are assigned numbers 1, 2, 3, and 4, respectively, and the corresponding binary codes (001), (010),
(011) and (100) are assigned.

The detection timing inputted to the AND gate corresponding to each light receiving element is a timing at which the digit of the binary code takes a value of "1". That is, the timing of the light receiving element 301 is t1, the timing of the light receiving element 302 is t2, the timing of the light receiving element 303 is t1 and t2, and the timing of the light receiving element 304 is t3.

If this is generalized, the function f (tk) (k
= 1, 2,...) Takes a value of 0 or 1,
When the number N of the light receiving element is represented by a binary number of the following equation (1),

(Equation 1) The N-th light receiving element has a time t satisfying f (tk) = 1.
It is assumed that detection is performed on k.

At this time, at the timing shown in FIG. 2, (t3, t2, t1) is the emission command at the time t1 in the one cycle of the emission command as the lower bit and the OR value at the time t3 as the most significant bit. When it is assumed that the output is one cycle, only the light emission command t1 is
When the R value is 1, the output of one cycle of the light emission command is (0,
0, 1), which means that an object exists in the detection area of the light receiving element 301 since it is uniquely determined that only the light receiving element 301 has detected the reflected light.

When the light receiving array outputs only the light emission command t2, the output of one cycle of the light emission command becomes (0, 1, 0). Means to do. Similarly, the light emission command t
When the light receiving array outputs for 1 and t2, 1
Since the output of the cycle is (0, 1, 1), the light receiving element 30
3 means that an object exists in the detection area.

In other words, the time-series output data of the detection signal OR value of these light receiving arrays in one cycle of the light emission command corresponds to the fact that each detection area is encoded by a binary number. The existence area of the object, that is, the distance to the object is calculated from the data and the camera parameters and the projector parameters, or the distance is obtained from the correspondence between the camera parameters and the projector parameters and a map created in advance.

As described above, based on the time series data of the light emission command and the light receiving array output value in one cycle of the light emission command,
The existence area of the object that reflects the irradiation light is uniquely determined, and the distance to the object can be obtained.

Assuming that the number of light receiving elements constituting the light receiving array is N, a predetermined area can be divided into a maximum of N to perform distance measurement. Now, it is assumed that the light receiving array is composed of 128 light receiving elements. At this time, since the information amount of 7 bits is required to divide the monitoring area into 128, the light emission command is
It is necessary from t1 to t7. Here, tN (N = 1 to
7) is 10 μs, and the light emission interval from the fall of the light emission command to the rise of the next light emission command is 10 μs.
Assuming that the light emission period is 20 μs, 7 × 20 is required to detect all 7-bit states, ie, to calculate the distance.
μs = 140 μs is required, and the distance can be detected in a very short time.

The above description has been made assuming that the number of light receiving arrays is one. By arranging a plurality of light receiving arrays in parallel,
It can be applied to unevenness detection and multi-target identification, and three-dimensional shape measurement can be performed by scanning slit light.

Next, a case where the distance measuring device according to the present invention is applied to a vehicle will be described with reference to FIGS.

As shown in FIG. 3, the one-dimensional light-receiving element array 30 is arranged so as to monitor the front of the vehicle and the one-dimensional light-receiving element array 30 is perpendicular to the ground. Is arranged in front of the vehicle so as to emit slit light or spot light so as to be perpendicular to the one-dimensional array, so that the distance to an obstacle in front of the vehicle can be measured.

Then, as shown in FIG. 3A, the range of the distance to be measured is divided into regions 1, 2, 3, and 4, and it is determined which region has the distance measurement target. .
In this distance measurement, there are three types of timings at which the light receiving element array detects the reflected light from the target object: t1, t2, and t3.

At the timing of t1, as shown in FIGS. 3B and 3E, the presence or absence of reflected light from the regions 1 and 3 is detected. At the timing of t2, FIGS. 3C and 3F As shown in FIG. 3), the presence or absence of reflected light from the region 2 and the region 3 is detected. At the timing t3, the presence or absence of reflected light from the region 4 is detected as shown in FIGS. I do.

Next, a method of coding an area where an object exists will be described with reference to the timing chart shown in FIG. At time t1, the light-receiving element array forming the one-dimensional array has the regions 1 and 3 shown in FIG.
Synchronous detection is performed so as to detect only the reflected light from. That is, at the time t1, the light other than the light reflected from the region 1 and the region 3 is not detected. Similarly, at time t2,
Only the reflected light from the areas 2 and 3 is detected, and at time t3, only the reflected light from the area 4 is detected. At this time, when the vehicle-side surface of the object 21 exists in the region 3 as shown in FIG. 4, the slit light or the spot light emitted from the light projector 10 forms a projected image on the object 21. A light-receiving image is formed on the light-receiving element array of the one-dimensional array 30 from the projected image.

In the above case, in the timing chart of the synchronous detection shown in FIG. 2, the reflected light is detected at time t1 and time t2, and the time series data of the detection signal output in one cycle of the light emission command is expressed by ( 0, 1, 1). This corresponds to the binary notation of 3 and means that an object exists in the area 3.

Up to this point, description has been made based on the timing chart of synchronous detection in the case where each area is represented in binary. However, the timing of synchronous detection may be any timing that can uniquely identify each area.

[Brief description of the drawings]

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

FIG. 2 is a time chart for explaining a drive timing of a light projector and a detection timing of a detection signal of each light receiving region in the embodiment.

FIG. 3 is a diagram schematically illustrating a monitoring region of a light receiving element array according to an example of an embodiment.

FIG. 4 is a diagram schematically illustrating a state when an object is present according to an example of the embodiment;

FIG. 5 is an explanatory diagram for converting a distance range to an object into a binary code string.

FIG. 6 is an explanatory diagram of multi-target identification.

FIG. 7 is a diagram illustrating the principle of triangulation.

FIG. 8A is a diagram showing a two-dimensional pixel array of a CCD image sensor in a conventional example. FIG. 3B is a waveform diagram illustrating an arrangement order of pixel outputs constituting a horizontal scanning line in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Projector 11 Light emitting element 12 Light projecting lens 13 Drive circuit 21 Object 30 Light receiving element array 301, 302, 303, 304 Light receiving element 33 Signal processing circuit 34 Timing generation circuit 35 Logical OR circuit

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G02B 7/28 G02B 7/11 NF term (Reference) 2F065 AA02 AA06 AA54 BB05 BB29 CC11 DD06 FF09 FF24 GG03 GG06 GG07 HH04 HH05 JJ05 JJ18 JJ25 LL30 NN08 QQ14 QQ27 QQ28 2F112 AA08 BA05 CA05 CA08 CA12 DA25 DA26 EA03 FA29 2H051 BB20 BB25 CB20 CC04 CC10 CE16 DA07 DA19 DA22

Claims (6)

[Claims] 1. A light projecting means for projecting irradiation light in a first direction and a predetermined distance from the light projecting means in a predetermined second direction perpendicular to the first direction. A distance measuring device provided with a light receiving unit arranged to receive reflected light reflected by the object in the predetermined direction, wherein the light receiving unit detects reflected light for each of a plurality of regions arranged in the second direction A distance measuring device that measures a range of a distance to an object by determining which of the plurality of regions the reflected light is incident on. 2. The distance measuring device according to claim 1, wherein the irradiation light is a spot light or a slit light. 3. A unique binary code is assigned to each of the plurality of regions of the light receiving means, and the light emitting means emits light at a plurality of light emission timings corresponding to the number of digits of the binary code. Is determined at the timing when each digit of the assigned binary code is “1”, and whether reflected light is incident or not is calculated, and the logical sum of the determination result for each area is calculated. 3. The distance measuring apparatus according to claim 1, wherein a time series signal of a binary code indicating a region where the reflected light is incident is obtained. 4. The light projecting means modulates the intensity of irradiation light,
The distance measuring apparatus according to any one of claims 1 to 3, wherein the light receiving unit detects an intensity signal of the reflected light to determine in which area the reflected light is incident. 5. The apparatus according to claim 1, wherein the length of each of the plurality of regions arranged in the second direction is optimized to be unequal according to the purpose of measurement. The distance measuring device according to claim 4. 6. A method according to claim 1, wherein a plurality of said light receiving means are arranged in a third direction perpendicular to said first and second directions, respectively, to detect a shape of the object or a plurality of objects. The distance measuring device according to claim 5.