JP2001066126A - Range finder device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable measurement of three dimensional position information of an object every field cycle as a distance image and to enable distance measurement including reduced distance measurement error caused by the movement of the object between fields. SOLUTION: This device comprises a light source means 101 for projecting light with light intensity modulation differing every field cycle, a camera signal processing means 113 for picking up images of two timely-adjacent fields from reflected light from an object, and a distance calculating means 114 for measuring three-dimensional position information of the object every field cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a range finder for measuring three-dimensional information of a subject.

[0002]

2. Description of the Related Art As a conventional range finder device, for example, there is one as shown in FIG.

Hereinafter, the configuration of a conventional range finder device will be described with reference to FIG.

[0006] In FIG. 16, an optical filter 1002 is disposed in front of a light source 1001.
The slit 1003 is arranged on the exit side of the.

The vertical slit light generated by the slit 1003 is emitted to the subject OB via a rotating mirror 1004. The light source 1001 is controlled by the light source controller 1005, and the slit 1003 is controlled by the slit control unit 100.
6 is controlled. The rotation mirror 1004 is controlled by a rotation control unit 1007.

On the other hand, the reflected light from the object OB is
At 008, the light is received, enters the half mirror 1009, and is branched. An optical filter 1010 and an image sensor 1011 are arranged on the optical axis on the transmission side of the half mirror 1009. An image sensor 1012 is arranged on the optical axis on the reflection side of the half mirror 1009.

An image processing unit 1013 is connected to a video output terminal of the image sensor 1011, and a memory 1014 is laid on the image processing unit 1013. Further, the distance calculation unit 101
5, light source controller 1005, slit control unit 100
6, the control unit 1016 controls the rotation control unit 1007.

[0008] The operation of the conventional range finder device configured as described above will be described in detail.

Light emitted from a light source 1001 passes through an optical filter 1002, becomes light having a certain infrared wavelength characteristic, and is turned into vertical slit light by a slit 1003. This is swept in the horizontal direction by the rotating mirror 1004 to project slit light on the object OB. When a laser is used as the light source, the wavelength of the laser light is concentrated on the wavelength unique to the laser, so that a configuration without the optical filter 1002 can be employed.

The sweep of the slit light by the rotating mirror 1004 is performed once in one field in the horizontal direction. In the case where the image pickup by the image pickup device is non-interlace, it is performed once in one frame in the horizontal direction. At this time, the light source controller 1005 controls the light intensity of the light source 1001 so as to gradually increase the light intensity in the first sweep and gradually decrease the light intensity in the second sweep.

The light generated in this manner is used as the object OB.
And the reflected light is captured by the image sensor 1011. In this case, the exposure is performed without the shutter operation, the reflected light of the light scanned in each field (frame) is accumulated in the image sensor, and the captured image is transferred to the image processing unit 1013.

The image processing unit 1013 stores the image captured in the first field portion in the memory 1014, synchronizes the image captured with the image stored in the second field portion with the same coordinates of each image. Is referred to.

The specific angle θ is determined by the combination of the brightness value of the image obtained by the first sweep and the brightness value of the image obtained by the second sweep. That is, one range image can be obtained in two fields (frames).

For example, assuming that the x-coordinate at time t1 is equal to the x-coordinate of the image at t2, the luminance (magnitude of the image signal) is measured, and when it becomes L1 and L2, the value of L1 / L2 is calculated. To specify the angle θ.

On the other hand, each pixel position of the image sensor and the lens 10
The line-of-sight angle φ determined by the line of sight formed by the center of 08 and the optical axis of the lens 1008 is a known value corresponding to each pixel position on a one-to-one basis. Further, the distance D between the center of the lens 1008 and the rotation center of the rotating mirror 1004 is also known.

The distance calculation unit 1015 obtains distance information of the entire screen for each pixel according to the principle of triangulation and outputs it as a distance image.

The texture image is stored in the image sensor 1012.
The image signal is converted into an image signal by the color camera signal processing unit 1017 and output as a texture image. At this time, two texture images are obtained for one distance image. This is because a frame is composed of two fields, and a texture image is composed of frames. One of the two texture images is output after calculating the average value of each of the pixels.

[0018]

However, the configuration of the above-described conventional range finder has the following problems.

In the conventional configuration, since the distance image is obtained as a field image for each frame cycle, the number of pixels of the distance image is only half the number of pixels included in the entire frame. In other words, there is a problem that only a half distance image of the number of fields (or the number of frames) of the texture image can be obtained.

Further, the conventional configuration has a problem that when the distance of a moving subject is measured, a measurement error occurs due to the movement of the subject between fields (or between frames).

In the conventional configuration, when a laser is used as the light source, the oscillation mode changes when the intensity of the laser light is modulated, thereby changing the oscillation wavelength, and as a result, the intensity of the light to be imaged is unstable. There was a problem that may be.

Further, in the conventional configuration, since the intensity of the light source is modulated, it is impossible to scan the measurement space in a state where the output of the light source is maximized, and there is a problem that the light use efficiency is reduced.

The present invention has been made in view of the above point, and can measure three-dimensional position information of a subject as a distance image in each field cycle, and can reduce a distance measurement error caused by the movement of the subject between fields. An object of the present invention is to enable a reduced distance measurement.

Further, the present invention performs the light intensity modulation by controlling the angular velocity of the rotating mirror so that, when a laser is used as the light source, the distance can be measured without being affected by the oscillation mode change at the time of laser light intensity modulation. It is another object of the present invention to perform distance measurement with improved light use efficiency.

Further, according to the present invention, the light intensity modulation and the light sweep to the object are performed simultaneously by rotating the rotating mirror at a constant angular velocity by making the shape of the rotating mirror a curved surface. This allows distance measurement to be performed without being affected by the oscillation mode change at the time of intensity modulation of laser light when a laser is used as the light source, and enables distance measurement with improved light use efficiency. The purpose is to do.

[0026]

An apparatus according to the present invention comprises:
Light source means for projecting light subjected to light intensity modulation different for each field cycle to a subject; camera signal processing means for capturing images of two fields which are temporally adjacent from reflected light from the subject; And a distance calculating means for measuring the three-dimensional position information of the subject, so that the three-dimensional position information can be measured for each field cycle.

Therefore, three-dimensional position information (distance image) having the same number of pixels as the number of pixels of the texture image can be created.

Further, the apparatus according to the present invention includes a field memory for holding distance images of three fields which are temporally adjacent to each other, and a time median filter for performing a median process in the time direction for each pixel, and By calculating the value of the distance image at each pixel as the median value of the distance image of the previous field, the current field, and the next field, it is possible to reduce the distance measurement error caused by the movement of the subject between the fields.

Further, the apparatus according to the present invention comprises a field memory for holding distance images for three fields which are temporally adjacent to each other, a subtractor for detecting a time change of the distance value, and a threshold value for the time change of the distance value. A delay selection circuit that outputs a distance value at the same coordinate value of the next field when the distance value is equal to or greater than the threshold value, and outputs a distance value of the current field when the time change of the distance value is equal to or less than the threshold value; The distance measurement error caused by the movement of the subject can be reduced.

Further, the apparatus according to the present invention modulates the light intensity by changing the angular velocity of the rotating mirror within the field period. When a laser is used as a light source, the oscillation mode change at the time of intensity modulation of the laser light. And the distance measurement with high light use efficiency can be performed.

Further, the apparatus according to the present invention is characterized in that the rotating mirror has a curved surface, the light intensity modulation and the light sweeping of the object are simultaneously performed by rotating the rotating mirror at a constant angular velocity, and the laser is used as the light source. The distance measurement can be performed without being affected by the oscillation mode change at the time of light intensity modulation, and the distance measurement with improved light use efficiency can be performed.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A range finder device according to a first aspect of the present invention comprises: a light source means for projecting light, which has been subjected to different light intensity modulation for each field period, to a subject; Camera signal processing means for capturing images of two adjacent fields, and distance calculating means for measuring three-dimensional position information of the subject for each field cycle.

With this configuration, three-dimensional position information can be measured for each field cycle. Therefore, three-dimensional position information (distance image) having the same number of pixels as the number of pixels of the texture image can be created.

According to a second aspect of the present invention, in the range finder according to the first aspect, the distance calculating means determines whether the image of the current field is an even field or an odd field.
There is provided switching means for switching the measurement method of the three-dimensional position information depending on whether it is a field.

With this configuration, even if the three-dimensional position information is measured for each field period, the three-dimensional position information can be accurately measured.

According to a third aspect of the present invention, in the range finder device according to the first aspect or the second aspect, the distance calculation means holds three-dimensional position information of three temporally adjacent fields. A field memory, and a time median filter for performing a median process in the time direction for each pixel, and the values of the three-dimensional position information at each pixel of the current field are stored in the previous field, the current field,
It is calculated as the median value of the three-dimensional position information of the next field.

As described above, by performing the median processing on the three-dimensional position information of each pixel in the time direction, it is possible to reduce the measurement error of the three-dimensional position information caused by the movement of the subject.

According to a fourth aspect of the present invention, in the range finder according to the first aspect or the second aspect, the distance calculating means holds three-dimensional position information for three temporally adjacent fields. A field memory, a subtractor for detecting a time change of the three-dimensional position information, and, when the time change of the three-dimensional position information is equal to or greater than a threshold value, outputting the three-dimensional position information at the same coordinate value of the next field; A delay selection circuit that outputs the three-dimensional position information of the current field when the time change of the three-dimensional position information is equal to or smaller than the threshold value.

With this configuration, it is possible to reduce the measurement error of the three-dimensional position information caused by the movement of the subject between fields.

According to a fifth aspect of the present invention, in the range finder device according to any one of the first to fourth aspects, a rotating mirror for sweeping light to a subject and an angular velocity of the rotating mirror are controlled. And an angular velocity variable rotation control unit for performing light intensity modulation.

With such a configuration, even when a laser is used as the light source, there is no influence of the oscillation mode change at the time of intensity modulation of the laser beam. Further, with this configuration, distance measurement with high light use efficiency can be performed.

According to a sixth aspect of the present invention, there is provided a range finder device according to any one of the first to fourth aspects, wherein a curved surface rotating mirror for sweeping light on a subject and an angular velocity of the curved surface rotating mirror are provided. And a rotation control unit for performing light intensity modulation by controlling the rotation angle to a constant angular velocity.

With such a configuration, even when a laser is used as a light source, there is no influence of the oscillation mode change at the time of laser light intensity modulation. Further, with this configuration, distance measurement with high light use efficiency can be performed.

Hereinafter, a range finder according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a range finder device according to an embodiment of the present invention. The configuration of the above embodiment will be described below with reference to FIG.

An optical filter 102 is disposed in front of a light source 101, and a slit 10 is provided on an emission side of the optical filter 102.
3 are arranged.

The vertical slit light generated by the slit 103 is applied to the subject OB via the rotating mirror 104. The light source 101 is controlled by a light source controller 105, and the slit 103 is controlled by a slit control unit 106. The rotation mirror 104 is controlled by the rotation control unit 107.

On the other hand, the reflected light from the object OB is
At 08, the light is received, enters the half mirror 109, and is branched.
The optical filter 1 is placed on the optical axis on the transmission side of the half mirror 109.
10. An image sensor (hereinafter, referred to as a CCD) 111 is provided. An image sensor 112 is arranged on the optical axis on the reflection side of the half mirror 109.

The video output terminal of the CCD 111 is connected to the CCD 1
An infrared camera signal processing unit 113 that performs normal video signal processing on the output signals of the eleventh output signal is connected.

A distance calculation unit 114 for calculating a one-field distance image from two temporally adjacent infrared images, a light source controller 105, and a slit control unit 1
06, the control unit 115 controls the rotation control unit 107.

The color camera signal processing section 116 converts an image picked up by the image pickup device 112 into an image signal and outputs it as a texture image. The image cutout unit 117
Cut out the texture image using the distance.

The operation of the range finder according to the first embodiment of the present invention will be described in detail.

The light emitted from the light source 101 is
02, it becomes light having a certain infrared wavelength characteristic, and becomes slit light in the vertical direction by the slit 103. This is swept in the horizontal direction by the rotating mirror 104 and the object O
The slit light is projected on B.

The sweep of the slit light by the rotating mirror 104 is performed once in the horizontal direction in one field as shown in FIG. In the case where the image pickup by the image pickup device is non-interlace, it is performed once in one frame in the horizontal direction.

At this time, as shown in FIG. 2B, the light source controller 105 gradually increases the light intensity in the first sweep and gradually reduces the light intensity in the second sweep. The light intensity of 101 is controlled.

The light generated in this manner is used as the object OB.
, And the reflected light is captured by the CCD 111. In this case, the exposure is in a state where there is no shutter operation,
The reflected light of the light scanned in each field (frame) is accumulated in the image sensor, and the captured image is transferred to the infrared camera signal processing unit 113.

The texture image is picked up by the image pickup device 112, turned into an image signal by the color camera signal processing section 116, and output as a texture image.

Here, the infrared camera signal processing unit 113 and the distance calculation unit 114, which are features of the present embodiment, will be described in detail.

The infrared camera signal processing unit 113 includes a CCD 1
Normal video signal processing is performed on the 11 output signals.

The distance calculation unit 114 determines that two temporally adjacent
A one-field range image is calculated from the two-field infrared images.

FIG. 3 is a block diagram showing the configuration of the distance calculator according to the above embodiment.

Reference numeral 301 denotes an A / D converter, and 302 denotes a previous field (current field (hereinafter, referred to as current field)).
A field memory for storing the field one field before (the field one field before).

Reference numeral 303 denotes an inter-line interpolator for inter-line interpolation of the previous field. A switch 304 switches the denominator for the luminance ratio calculation and the input to the numerator in a field cycle depending on which of the previous field and the current field is the even field.

Reference numeral 305 denotes a luminance ratio calculation circuit, and 306 denotes a distance conversion circuit. A spatial median processing unit 307 performs spatial median processing on the distance image.

Reference numeral 308 denotes a temporal median processing unit that temporally performs median processing on the distance image.

Here, the operation of the distance calculation unit according to the above embodiment will be described with reference to the drawings.

The A / D converter 301 converts the infrared image into an A / D signal.
Convert. The A / D converted image is stored in the field memory 3
02 is held. At the time of the current field processing, the data of the previous field held in the field memory 302 is inter-line interpolated by the inter-line interpolator 303. This is for correcting a difference in the imaging position between the current field and the previous field (a difference of one line due to interlace).

The SW 304 outputs a denominator to the luminance ratio calculation circuit 305 depending on which of the current field and the previous field is the Even field and which is the Odd field.
Switches the input to the molecule at the field cycle. By this switching operation, the luminance ratio calculation circuit 305 can correctly calculate the light intensity ratio regardless of whether the current field is the Even field or the Odd field.

Also, by having the SW 304 as described above, the light intensity ratio of each pixel can be calculated for each field cycle, and therefore, a specific angle θ (FIG.
Is determined from the function of (c). Therefore, a distance image can be created for each field cycle by a processing procedure described later. As described above, since a distance image can be created for each field cycle, distance image data having the same number of frame pixels can be created.

For example, assuming that the x-coordinate at time t1 is equal to the x-coordinate of the image at time t2 which is continuous with time t1, the luminance (magnitude of the image signal) is measured. / L2 is calculated and according to FIG.
Specify the angle θ.

At this time, the value of the ratio of L1 / L2 depends on the texture pattern (color distribution) even if there is a texture pattern (color distribution) on the surface of the object, because the reflected light of the object to the same light source is captured although the intensity is different. do not do. This makes it possible to estimate the angle θ with high accuracy.

On the other hand, each pixel position of the image sensor and the lens 10
The line-of-sight angle φ (see FIG. 1) determined by the line of sight formed by the center of 8 and the optical axis of the lens 108 is a known value corresponding to each pixel position on a one-to-one basis. Also, lens 1
08 and the rotation center of the rotation mirror 104
(See FIG. 1) is also known.

The distance conversion circuit 306 substitutes the projection angle θ, the line-of-sight angle φ, and the distance D into (Equation 1) for each pixel according to the principle of triangulation to obtain a value on the object OB corresponding to the pixel. A distance Z between each point and a base line (a line segment connecting the center of the lens 108 and the rotation center of the rotating mirror 104) is calculated, a distance over the entire screen is obtained, and a distance image is output.

(Equation 1) The spatial median processing unit 307 replaces the distance value at each pixel in the same distance image with the median value of the distance value at neighboring pixels, and improves the accuracy of the distance measurement value.

The temporal median processing unit 308 performs a median process on a temporal change of each pixel in the range image. The time median processing can reduce a distance measurement error caused by the movement of the subject.

FIG. 4 is a diagram for explaining a distance measurement error caused by the movement of a subject. FIG. 4A is a diagram for explaining the movement of a subject between fields.
4B is a diagram for explaining the distribution of the reflectance of the foreground (subject) and the background, and FIG. 4C is a diagram for explaining the distribution of the distance between the foreground (subject) and the background.

In the above embodiment, the light intensity ratio is calculated from the images of the two fields and the distance is converted. Therefore, as shown in FIG. 4A, a moving subject has a different imaging position. Here, for simplicity, an embodiment using a subject and a background having a uniform distance and a uniform reflectance will be described.

As shown by solid lines in FIGS. 4 (b) and 4 (c), a subject having a uniform reflectance and uniform reflectance in front of a background having a uniform distance moves. When you are (for simplicity A
When the light intensity ratio is calculated from the two-field image and the distance is converted, the distance indicated by the broken line is measured in the contour part (between ab and cd) of the subject, An error occurs.

This is because the processing for converting the distance from the light intensity ratio for the same point on the subject is not performed by the movement of the subject.

FIG. 5A is a diagram for explaining how an error occurs in the light source intensity with respect to the angle from the light source due to the movement of the subject in the above embodiment. FIG.
(B) is a diagram for explaining how an error occurs in the light source intensity with respect to the angle from the light source due to the movement of the subject in the embodiment. FIG. 5C is a diagram for explaining how an error occurs in the light intensity ratio with respect to the angle from the light source due to the movement of the subject in the above embodiment.

Considering the case where the current field in FIG. 5 (a) is the Odd field, as shown in FIG. 5 (a), the light intensity of the Even field (actually multiplied by the reflectance of the subject) depends on the movement of the subject. Changes).

Due to this change in light intensity, the light intensity ratio changes as shown in FIG. The angle θ from the light source is
Whether the decrease or increase is caused by the movement of the subject depends on both the reflectance of the subject and the background and whether the current field is the Even field or the Odd field.

For example, when the light intensity increases due to the movement of the subject, and when the current field is the Odd field (FIG. 5A), an error regarding the angle θ from the light source occurs in a direction in which θ increases, and conversely. When the current field is the Even field (FIG. 5B), an error in θ occurs in a direction in which θ decreases.

In the case of the example shown in FIG. 4 (the current field is Od
In the d field, when the foreground is brighter than the background, the distance is measured on the left side of the subject (A side in FIG. 4A) before the actual distance, and the distance is measured on the right side of the subject (FIG. 4A). Of B
Side), the distance is measured deeper than the actual distance.

FIG. 6 is an explanatory diagram of the distance measurement error caused by the continuous movement of the subject. FIG. 6A is a diagram for explaining the movement of a subject between fields.
FIG. 6B is a diagram for explaining the distribution of the distance of the subject for the t field, FIG. 6C is a diagram for explaining the distribution of the distance of the subject for the t + 1 field, and FIG. , T + 2, is a diagram for explaining the distribution of the distance of the subject in the field.

FIGS. 6 (b), 6 (c) and 6 (d) show the continuous measurement of the moving subject shown in FIG. 6 (a). 1) shows a one-dimensional distribution between AB).

6 (b), 6 (c) and 6 (d), the solid line is the measured distance value, and the dotted line is the true distance value.

Focusing on the measured values in FIG. 6C, by performing median processing in the time direction taking into account one field before and after, the measurement error (position P The error caused by the above is suppressed. At the position P, the background distance is measured in the previous field, the foreground distance is measured in the current field, and the foreground distance is measured in the next field. Therefore, the foreground distance is selected by temporal median processing, and the measurement error is suppressed. Conversely, the measurement error on the A side of the subject is not suppressed by the time median processing.

FIG. 7 is a block diagram showing the configuration of the time median processing unit according to the above embodiment.

In FIG. 7, reference numerals 701A and 701B denote field memories for holding field images delayed by one field and two fields, respectively.
2B is an inter-line interpolation circuit for correcting a difference in the imaging position between fields (a shift in the imaging position for one line);
A median circuit 703 performs a median process in the time direction for each pixel.

Returning to FIG. 1, the image cutout unit 117
Cut out the texture image using the distance.

FIG. 8 is a block diagram showing the configuration of the image clipping section according to the above embodiment.

In FIG. 8, reference numeral 801 denotes an A / D converter for A / D converting a texture image; 802, a synchronization adjustment circuit for adjusting synchronization between a distance image and a color image; 803, an image cutout unit based on distance; 804B, 804C
Are D / A converters 805A, 805B, and 8 for D / A converting the texture image, the cutout image, and the distance image, respectively.
05C is a switch for switching between analog output and digital output.

As described above, according to the above-described embodiment, since the light intensity ratio of each pixel can be calculated for each field cycle, the distance information can be measured for each field cycle, so that a distance image can be created. As described above, since a distance image can be created for each field cycle, a distance image having the same number of frame pixels as the distance image can be created.

Further, according to the above-described embodiment, the measurement error can be suppressed by performing the median processing in the time direction on the distance measurement error caused by the movement of the subject.

Further, in the above embodiment, the temporal median processing is performed on all the pixels in the distance image. However, the temporal median processing is performed only on the pixels whose distance changes between fields. It is obvious that the same effect can be obtained, and is included in the present invention.

Hereinafter, a modification of the above embodiment will be described.

This embodiment focuses on the fact that, in FIG. 6C, the true distance value of the areas P and Q where a measurement error has occurred is measured in the next field, and the pixel whose distance changes between fields is used. Is a form in which the distance value at the pixel is a distance measurement value at the same coordinate value in the next field (the same coordinate value when considered as a field image). That is, the time median processing unit 308 in FIG.
Is replaced by a delay selection unit that performs the above processing.

FIG. 9 is a block diagram showing a configuration of a delay selector according to a modification of the above embodiment. Using this figure, a modification of the above embodiment will be described in detail.

In FIG. 9, reference numeral 901 denotes a selection delay unit according to a modification of the above embodiment, 902A and 902B denote interline interpolators, 903A and 903B denote field memories,
904 is a selection switch. The selection switch 904 is
When the difference between the distance value of the current field (the read signal from the field memory 903A) and the distance value of the previous field (the output signal of the interline interpolator) is equal to or smaller than a certain threshold value, the distance value of the current field is output. By outputting the distance value (readout signal from the field memory 903B) of the next field when the threshold value is exceeded, delay selection is performed for each pixel of the distance image.

As described above, this embodiment can also reduce the distance measurement error caused by the movement of the subject. This mode is also included in the present invention as a matter of course.

The same effect can be obtained by detecting a pixel whose distance changes between fields as described above even if the pixel is extracted as a region where the light intensity changes between frames. This embodiment is also included in the present invention.

Further, the detection of the pixel whose distance changes between the fields is performed in the same manner as in the present embodiment since the light intensity ratio corresponds to the distance even if the pixel is extracted as an area where the light intensity ratio changes between the fields. It is clear that the effect can be obtained and is included in the present invention.

FIG. 10 is a block diagram of a range finder device according to another modification of the present invention. In FIG. 10, components that perform the same operations as those in the first embodiment of the present invention are given the same reference numerals as in FIG. 1, and descriptions thereof are omitted. Here, the light source controller 1101 and the angular velocity variable rotation control unit 11 that operate differently from the first embodiment
02 will be described. In FIG. 10,
A laser light source is used as the light source 101, and the optical filter 1 is used.
02 may not be used.

The light source controller 1101 can control the light source 101 to emit light with a constant light intensity in addition to the operation of the light source controller 105 shown in FIG.

The variable angular velocity rotation control unit 1102 includes, in addition to the operation of the rotation control unit 107 shown in FIG.
4 can be controlled to modulate the light intensity projected onto the subject. FIG. 11A is a timing chart of a sweep angle by a rotating mirror according to the other modified embodiment. FIG.
(B) is a timing chart of the projection light amount according to another modification. FIG. 11C is a diagram illustrating a relationship between a light intensity ratio and an angle θ from a light source according to another modification. In the first embodiment of the present invention, the light intensity is modulated by sweeping the slit light so that the sweep angle θ is linear with respect to time and changing the light intensity of the light source. The light intensity of the light source is fixed, and the light intensity is modulated by sweeping the sweep angle θ nonlinearly with respect to time.

When the angle θ is set in the direction shown in FIG. 10, the light intensity L (θ) in the θ direction is proportional to the power P of the light source and inversely proportional to the sweep angular velocity.

(Equation 2) Can be expressed as Therefore, by the sweep shown in FIG. 11A, the light intensity in the θ direction becomes as shown in FIG. 11B.

Considering that the angle θ is controlled so that L (θ) changes linearly,

(Equation 3) From (Equation 2) and (Equation 3)

(Equation 4) Becomes The constants A, B, a, b, and c are defined as the range of the sweep angle (that is, the value of θ at the start and end of the field) and the range of the light intensity used in the light intensity modulation (that is, at the start and end of the field). Light intensity value) and the symmetry of the characteristics described later.

Note that the time characteristic of the sweep angle and the time characteristic of the light intensity are different depending on the even field and the odd field. Characteristics of both fields

(Equation 5)

(Equation 6) , The light intensity ratio (L1−L2) / (L1 + L
The denominator of 2) becomes a constant value, and as shown in FIG. 11C, the relationship between the sweep angle θ and the light intensity ratio (L1−L2) / (L1 + L2) can be linearized. At the time of measurement, since the sweep angle θ is calculated from the light intensity ratio, if the relationship between the two is linear, the accuracy of θ can be made constant regardless of the value of the light intensity ratio.

Further, in the present embodiment, the control of the sweep angle θ has been described, but the range of the swing angle ρ of the rotating mirror is の of the range of the sweep angle. That is,

(Equation 7) There is a relationship.

As described above, according to the above embodiment, the light intensity of the light source can be kept constant, and the light intensity can be modulated by nonlinearly controlling the rotating mirror (ie, controlling the sweep angle). Accordingly, when the laser is used as the light source, the oscillation mode does not change, and stable distance measurement can be performed. In addition, since the measurement can be performed with the light intensity of the light source kept constant at the maximum value, distance measurement with improved light use efficiency can be performed.

In the above embodiment, for simplicity, an example in which the relationship between the light intensity L and the sweep angle θ is linearized as shown in (Equation 3) has been described. The relationship between the angle information tanθ regarding θ and the light intensity L may be linearized. Linearizing the relationship between tan θ and the light intensity L means that the light intensity projected on a Z = constant plane is X
It means that it changes linearly in the axial direction. In that case,
From (Equation 8) and (Equation 9),

(Equation 8)

(Equation 9) The relationship between θ and t is shown in (Equation 10).

(Equation 10) As described above, the rotation control unit 1102 modulates the light intensity by changing the angular velocity of the rotating mirror within the field period, so that when the laser is used as the light source, the oscillation mode at the time of laser light intensity modulation is used. The distance measurement can be performed without being affected by the change and with high light use efficiency.

FIG. 12 is a configuration diagram of a range finder device according to another modification of the present invention. 12, the same operations as those in the first embodiment of the present invention and the modifications thereof are denoted by the same reference numerals as those in FIG. 1 or FIG. 10, and the description will be omitted. here,
The operations of the curved surface rotation mirror 1103 and the rotation control unit 1104 that operate differently from the first embodiment and the modified embodiment will be described. Note that in FIG.
A configuration may be adopted in which a laser light source is used as 1 and the optical filter 102 is not used.

The curved rotating mirror 1103 is a cylindrical curved mirror. The curved surface rotation mirror 1103 is driven by the rotation control unit 1104, and rotates 30 times per second in synchronization with the frame period. Light emitted from the light source passes through the slit to become slit light. The slit light is reflected on the side surface of the curved rotating mirror and projected on the subject space.
In the present embodiment, control is performed so that the light source 101 emits light at a constant light intensity.

The sweeping of the projection light and the light intensity modulation of the projection light are performed by the curved rotating mirror 1103 reflecting the slit light.
Is changed within the field period (that is, the period during which the curved surface rotating mirror makes a half rotation). Hereinafter, a method for determining the shape of such a curved rotating mirror will be described.

FIG. 13 is a view for explaining the state of reflection of slit light by the curved surface rotating mirror 1103. For simplicity, consider the case where the slit light is parallel to the XY plane.
In FIG. 13, φ is the angle formed by the slit light and the contact surface of the curved rotating mirror 1103 at the slit light reflection position. r
Is the distance between the rotation center of the curved rotating mirror 1103 and the slit light reflection position. ρ0 is the angle of the slit light reflection position as viewed from the rotation center of the curved rotating mirror 1103. dr is the amount of change in r near the angle ρ0. β is the tangent surface of the cylinder with the radius r at the reflection position of the slit light and the curved surface rotating mirror 110
3 is the angle between the contact surfaces. The relationship between the sweep angle θ and φ in FIG.

[Equation 11] It is. Also,

[0116]

(Equation 12) The slit light reflection position and its angle ρ0 move with the rotation of the curved surface rotation mirror 1103, but if this is ignored as a minute value, from (Equation 12)

[0117]

(Equation 13) The diameter r of the curved mirror 1103 is defined as the angle φ of the contact surface.
Can be represented by

Curved surface rotating mirror 1 at slit light reflection position
The time characteristic of the contact surface angle φ of 103 is given by (Equation 11) and
It is determined by (Equation 4) or (Equation 10) from the condition for performing light intensity modulation. Therefore, (Equation 13) becomes (Equation 1)
By substituting 1) and (Equation 4) or (Equation 10) and considering that the curved rotating mirror 1103 makes one rotation in one frame period, the sectional shape of the curved rotating mirror 1103 can be determined.

FIG. 14 shows an example of the cross-sectional shape of the curved rotating mirror 1103 determined by the method described above. In the figure, the solid line indicates the cross-sectional shape of the curved rotating mirror, and the broken line is a circle for comparison. In FIG. 14, upper and lower halves perform light sweeping and light intensity modulation for one field.

In consideration of the movement of the slit light reflection position due to the rotation of the curved mirror 1103, if the slit light is parallel to the XY plane, the slit light reflection position P
Move under the condition of Z = constant due to the rotation of the curved rotating mirror 1103. FIG. 15 is a diagram illustrating a state in which slit light enters the curved surface rotating mirror 1103. FIG.
In O, O indicates the center of rotation of the curved rotating mirror, and P indicates the slit light reflection position. If the shape of the curved rotating mirror 1103 is represented as r (ρ) and it reaches the slit light reflection position at the time of rotating by τ, since the Z value of the slit light reflection position is constant,

[Equation 14] Becomes Therefore, the relationship between the direction φ of the contact surface of the curved rotating mirror 1103 and the shape r (ρ) of the curved rotating mirror 1103 is as follows.

[0121]

(Equation 15) It is expressed as The time characteristic of φ in (Equation 15) is determined by (Equation 11) and (Equation 4) or (Equation 10) from the condition of performing light intensity modulation. Therefore, (Equation 1)
Substituting (Equation 11) and (Equation 4) or (Equation 10) for 5), the curved surface rotating mirror 1103 is set to 1
By considering the rotation, the curved rotating mirror 1
103 can be determined. However, a mathematical expression obtained by substituting (Equation 11) and (Equation 4) or (Equation 10) into (Equation 15) cannot be solved analytically, and therefore needs to be solved numerically.

As described above, according to another modification of the present embodiment, the curved surface rotating mirror that rotates at a constant rotation speed reflects slit light whose light intensity does not change with time, so that the object space can be obtained. The light intensity modulation and the light sweep of the projection light to the light source can be performed simultaneously. In addition, when a laser is used as a light source, distance measurement with high light use efficiency can be performed without being affected by an oscillation mode change at the time of intensity modulation of laser light.

[0123]

As described above, according to the present invention,
The three-dimensional position information of the subject can be measured as a distance image in each field cycle, and the distance measurement can be performed with a reduced distance measurement error caused by the movement of the subject between fields. Further, even when a laser is used as a light source, distance measurement can be performed without being affected by a change in an oscillation mode at the time of intensity modulation of laser light. Further, it is possible to perform distance measurement with improved light use efficiency.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a range finder device according to an embodiment of the present invention.

2A is a timing chart of a sweep angle by a rotating mirror according to the embodiment; FIG. 2B is a timing chart of a light source light amount according to the embodiment; Showing the relationship of angle θ

FIG. 3 is a block diagram showing a configuration of a distance calculation unit according to the embodiment.

4A is a diagram for explaining the movement of a subject between fields. FIG. 4B is a diagram for explaining the distribution of the reflectance of the foreground (subject) and the background. It is a figure for explaining distribution of distance.

FIG. 5A is a diagram for explaining how an error occurs in light source intensity with respect to an angle from a light source due to movement of a subject in the embodiment. (B) A diagram for explaining how an error occurs in the light source intensity with respect to the angle from the light source due to the movement of the subject in the embodiment. (C) A diagram for explaining how an error occurs in a light intensity ratio with respect to an angle from a light source due to movement of a subject in the embodiment.

FIG. 6A is a diagram for explaining the movement of a subject between fields in the embodiment; FIG. 6B is a diagram for explaining the distribution of the distance of the subject for t fields in the embodiment; (C) A diagram for explaining the distribution of the distance of the subject in the t + 1 field in the above embodiment. (D) A diagram for explaining the distribution of the distance of the subject in the t + 2 field in the above embodiment.

FIG. 7 is a block diagram showing a configuration of a time median processing unit according to the embodiment.

FIG. 8 is a block diagram showing a configuration of an image cutout unit according to the embodiment.

FIG. 9 is a block diagram showing a configuration of a delay selection unit according to a modification of the embodiment.

FIG. 10 is a configuration diagram of a range finder device according to another modification of the embodiment of the present invention.

11A is a timing chart of a sweep angle by a rotating mirror according to another modification of the embodiment; FIG. 11B is a timing chart of a projection light amount according to another modification of the embodiment; The figure which shows the relationship between the light intensity ratio concerning deformation, and the angle (theta) from a light source.

FIG. 12 is a configuration diagram of a range finder device according to another modification of the embodiment of the present invention.

FIG. 13 is a view for explaining a state of slit light reflection by a curved rotating mirror;

FIG. 14 is an example of a cross-sectional shape of a curved rotating mirror;

FIG. 15 is a diagram illustrating a state of slit light reflection by a curved rotating mirror;

FIG. 16 is a block diagram showing a configuration of a conventional range finder device.

[Explanation of symbols]

111, 112 Image sensor (CCD) 113 Infrared camera signal processing unit 114 Distance calculation unit 116 Color camera signal processing unit 117 Image cutout unit OB Object 302, 701A, 701B, 903A, 903B Field memory 303 Interline interpolator 304 SW ( Switch) 305 Luminance ratio calculation circuit 306 Distance conversion circuit 307 Spatial median processing unit 308 Temporal median processing unit 702A, 702B Inter-line interpolation circuit 703 Median circuit 802 Synchronization adjustment circuit 803 Image cutout unit by distance 901 Selection delay unit 902A, 902B Between lines Interpolator 904 Selection SW (switch) 1101 Light source controller 1102 Variable angular speed rotation control unit 1103 Curved surface rotation mirror

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuo Noboru 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 2F065 AA04 AA06 BB15 CC21 DD00 DD04 EE00 EE05 FF01 FF04 FF09 FF65 GG04 GG21 HH05 HH07 JJ03 JJ05 JJ26 LL00 LL11 LL13 LL21 LL22 LL28 LL62 MM16 NN01 Q31Q28 Q25

Claims (6)

[Claims] 1. A light source means for projecting light subjected to light intensity modulation different for each field cycle to a subject, and a camera signal processing for capturing images of two fields which are temporally adjacent from the reflected light from the subject. And a distance calculating means for measuring the three-dimensional position information of the object for each field cycle. 2. The distance calculating means according to whether an image of a current field is an Even field or an Odd field.
2. The range finder according to claim 1, further comprising a switching unit for switching a method of measuring three-dimensional position information. 3. The distance calculating means includes a field memory for holding three-dimensional position information of three temporally adjacent fields, and a time median filter for performing a median process in a time direction for each pixel. And calculating a value of the three-dimensional position information in each pixel of the current field as a median value of the three-dimensional position information of the previous field, the current field, and the next field.
Alternatively, the range finder device according to claim 2. 4. The distance calculating means includes: a field memory for holding three-dimensional position information of three temporally adjacent fields; a subtractor for detecting a temporal change of the three-dimensional position information; When the time change of the three-dimensional position information is equal to or greater than the threshold value, the three-dimensional position information at the same coordinate value of the next field is output. 3. The range finder device according to claim 1, further comprising: a delay selection circuit that outputs a signal. 5. A rotating mirror for sweeping the light to the subject, and an angular velocity variable rotation control unit for performing the light intensity modulation by controlling an angular velocity of the rotating mirror. The range finder device according to claim 1. 6. A rotating mirror having a curved surface for sweeping the light to the subject and a rotation controller for performing the light intensity modulation by rotating the rotating mirror at a constant angular velocity. Claim 1 to Claim 4
The range finder device according to any one of the above.