JPH03163507A - Range-finding method and auxiliary light projecting device - Google Patents

Abstract

PURPOSE:To easily and surely correct an error caused by chromatic aberration in the case of executing range-finding by the use of auxiliary light by successively projecting two or more pattern images by light beams having different wavelengths and obtaining the deviation of the image every pattern. CONSTITUTION:The method is such a range-finding method that the pattern image IP is projected on an object 0 by an auxiliary light projecting device 1 and the image of the pattern image IP is formed on image sensors 4 and 5 by a pair of image-formation lenses 2 and 3 so that an object distance may be measured based on the deviation of the mutual images on the respective image sensors 4 and 5. By successively projecting two or more pattern images IP by the light beams having different wavelengths to the object 0, the deviation of the image is obtained corresponding to the respective pattern images IP. Thus, the deviation of the image is obtained every wavelength and how the error of the deviation of the image caused by the chromatic aberration is changed by the wavelength is known, thereby recognizing the object distance for a standard object.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance measuring method and an auxiliary floodlight device. INDUSTRIAL APPLICATION This invention can be utilized for a passive ranging device.

[Prior art] In passive ranging methods such as the TTL phase difference ranging method and the external light triangular ranging method, if the brightness of the subject is not sufficient, a pattern image is projected onto the subject using auxiliary light from an auxiliary light projector. When the brightness of the subject is sufficiently bright, distance measurement is performed using so-called "normal light" other than the auxiliary light. This distance measurement using normal light is set so that appropriate distance measurement can be performed for green light having a wavelength of about 550 nm.

Generally, an LED is used as a light source of the auxiliary floodlight device. L
ED has a narrow range of emission wavelengths, and generally many wavelengths range from red to infrared.

For this reason, it is known that when auxiliary light is used, errors due to chromatic aberration occur compared to normal distance measurement using only the tip.

Conventionally, such distance measurement errors due to chromatic aberration have been corrected when using the auxiliary light by using the distance measurement error between the normal light and the auxiliary light for a general subject as a correction value. However, this correction value is only a typical value, and in reality, sufficient correction has not been achieved.

The reason for this is thought to be that due to differences in the reflectance of the subject and the influence of external light, the reflected light from the subject during distance measurement becomes a mixture of external light and auxiliary light, so the distance measurement error due to chromatic aberration is not constant. .

[Problems to be Solved by the Invention] In order to eliminate errors caused by such chromatic aberrations, it has been proposed to perform distance measurement exclusively for visible light and for distance measurement exclusively for infrared light using separate distance measuring devices (particularly 1985-116626 public N
) requires two distance measuring devices, which increases the size and cost of the device.

The present invention was made in view of the above-mentioned circumstances, and
The object of the present invention is to provide a novel distance measuring method that can be realized with a small, low-cost device and that can reliably eliminate errors caused by chromatic aberration, and an auxiliary light projector used to implement this distance measuring method.

[Means for Solving the Problems] The present invention will be explained below. The distance measuring method of the present invention is to project a pattern image onto a subject using an auxiliary light projector, and form an image of the pattern image onto an image sensor corresponding to each imaging lens using a pair of imaging lenses. This is a passive ranging method that calculates the amount of deviation between the images on each image sensor and measures the distance to the subject based on the amount of deviation between the images. In contrast, 2 due to light of different wavelengths
The above-mentioned pattern images are sequentially projected, the amount of image deviation is determined for each pattern, and the object distance is determined based on the amount of image deviation with the influence of chromatic aberration removed at point J.

Further, the auxiliary light projection device of the present invention includes a projection lens and a pattern generating means for generating two or more types of patterns with different wavelengths.
and has.

[Function] When using auxiliary light, the distance measuring method of the present invention sequentially projects two or more pattern images with different wavelengths onto the subject, and calculates the amount of image shift corresponding to each pattern image. These amounts of image deviation include errors due to chromatic aberration, but since the amount of image deviation can be obtained for each wavelength, it is possible to know how the error in the amount of image deviation due to chromatic aberration changes with wavelength. By utilizing this fact, it is possible to know the object distance to a standard object (wavelength 550 nm).

[Example code] Hereinafter, description will be given based on specific examples.

In FIG. 1(I), code 0 indicates the subject.

A pattern image IP of a pattern P is projected onto this object O by a projection lens 1.

The image of the pattern image IP is formed on the corresponding image sensors 4 and 5 by a pair of imaging lenses 2 and 3, and is read by the image sensors 4 and 5.
The amount of deviation between the read images is calculated, and the distance measurement calculation is performed using the result to calculate the object distance.8 Pattern P is a transparent film with a transparent part and a light-shielding part as shown in Figure 1 (II), for example. It is a pattern.

The auxiliary floodlight device, as shown in Figure 2, irradiates pattern P independently with two types of LEDAs and B? It is now possible to Pattern P, LEDA, and B monitor the pattern generation means.

For example, the spectral characteristics of the brightness of these LEDAs and B are shown in Figure 1 (
III) curves Al and Bl.

Now, let's consider a case where distance measurement is performed under strong external light while also irradiating an auxiliary light. In the passive distance measuring method, the basis of distance calculation 'a' is the amount of deviation d between the images of the same pattern read by the image sensors 4 and 5, respectively.

As the amount of deviation d of this image, the LED as the auxiliary light source is
What is obtained when using dA1. If the value obtained when using an LEDB as the auxiliary light source is d■, when the influence of external light is large, the appropriate value obtained when measuring only external light is shown in Figure 1 (I■). The amount of image shift d0 and dAx - d■ are almost equal. That is, when the subject is sufficiently illuminated by external light, the auxiliary light has little effect on distance measurement, and almost no error due to chromatic aberration appears. In addition, in Figure 1 (■V), λ. ,λ. are the wavelengths that give the peak brightness values of LEDA and H, respectively. However, as the external light illuminating the subject gradually becomes weaker and the influence of the auxiliary light becomes stronger, the influence of chromatic aberration appears on the measurement. In other words, dA is the "image shift amount" obtained when using LEDA as the auxiliary light source under conditions where the influence of external light is small, and dA is the "image shift amount" obtained when using LEDB as the auxiliary light source. d. Then, the image shift amount dA and d. generally have different values due to chromatic aberration. The amount of image shift generally changes approximately linearly with the wavelength of the auxiliary light used. Figure 1 (The straight line 41 of m is d = {(da-dA)/(λ1λA)}λ+dA(
1). This will give you an appropriate subject distance without the effects of chromatic aberration.
The amount of image deviation doJ, that is, the amount of image deviation obtained when distance measurement is performed under sufficient normal light, is usually the standard wavelength λa (
= 550 nm), it is given by the following equation (2).

a6= {(dn-dA)/(λ1λA)}λO+d
A (2) where λ. /(λ1λA)=K, equation (2) is d o = K (d+s−dA) +
It is expressed as dA(3). On the right side of this equation (3), dA,
da is the "image shift amount" obtained by projecting the pattern image using LEDAs, B, and can be directly determined.

Also, K is λ. , λ8, and λ6, and among these, λ. is usually set as the distance measurement condition by the destination, and λ
9, λ6 is determined depending on the LEDA, B used as the auxiliary light source. Therefore, K is a constant in the distance measuring device. Therefore, by measuring the above dA and dll, it is possible to know the appropriate image shift amount d0, and by performing distance measurement calculations using this d0, it is possible to remove the influence of chromatic aberration and obtain the correct subject distance. .

FIG. 3 shows another example of the auxiliary floodlight device.

In this example, LEDC and D with different wavelengths are on the same board B.
It is deployed on S. If only the LEDC emits light, L
It is possible to generate a pattern in which the EDC is "bright" and the LEDD is "dark", and if only the LEDD emits light, the LED
A pattern in which D is "bright" and LEDC is "dark" can be generated.

That is, in this example, the LEDC and D, which are arranged adjacent to each other on the same surface of the substrate BS and selectively emit light, serve as pattern generating means. Also in FIG. 3, the reference numeral 1 naturally indicates the projection lens.

[Effects of the Invention] As described above, according to the present invention, a novel distance measuring method and an auxiliary floodlight device can be provided. According to the method of the present invention, errors caused by chromatic aberration can be easily and reliably corrected when distance measurement is performed using auxiliary light. Further, according to the auxiliary light projection device of the present invention, it is possible to realize the projection of a pattern image for realizing the above method.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the distance measuring method of the present invention, FIG. 2 is a diagram for explaining the auxiliary floodlight device used in the above embodiment, and FIG. FIG. 7 is a diagram for explaining another embodiment of the auxiliary floodlight device.

Claims (1)

[Claims] 1. Projecting a pattern image onto a subject using an auxiliary light projection device, and forming an image of the pattern image onto an image sensor corresponding to each imaging lens using a pair of imaging lenses; A passive distance measuring method that calculates the amount of deviation between the images on each image sensor and obtains the object distance based on the amount of image deviation. A distance measuring method characterized in that pattern images are sequentially projected, the amount of image shift is determined for each pattern, and the distance to a subject is determined based on the amount of shift of these images, with the effects of chromatic aberration removed. 2. An auxiliary light projection device having a projection lens and pattern generation means for generating two or more types of patterns with different wavelengths.