JP2758631B2 - Camera color measuring device and distance measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a colorimetric device for a camera and a distance measuring device using a colorimetric result obtained by the colorimetric device, and more specifically, to measure a spectral distribution of subject light. The present invention relates to a colorimetric device and a distance measuring device for a camera.

[Prior Art] A passive type distance measuring device for measuring a distance by using light from a subject has already been disclosed in U.S. Pat.
And JP-A-60-108816.
Many of these devices have errors in the distance measurement results and corrected values required for use due to the influence of the color of the subject, the distance measurement optical path due to the spectral distribution of the light source, and the chromatic aberration of other optical systems. Will occur. Therefore, means for measuring the color temperature of the light source with a sensor provided with a color filter and thereby correcting the error is disclosed in JP-A-63-168612 and JP-A-63-1686.
No. 13 and other publications.

[Problems to be Solved by the Invention] However, JP-A-63-168612 and JP-A-63-168613, in which the color temperature of a light source is measured by a sensor provided with a color filter, and the distance measurement value is corrected using the sensor. In the means disclosed in each of the publications, an erroneous correction is performed depending on the color of the subject, the type of the light source, and the like.

That is, in a light source such as a fluorescent lamp, a mercury lamp, and a sodium lamp, which deviates from the color temperature locus, the spectral distribution is detected as several vectors, so that the measured values are the same even if the spectral distributions are different. Sometimes. For example,
Tungsten lamps and fluorescent light bulbs have the same spectral luminous efficiency curve in the visible light region with a wavelength of about 400 to 700 nm, so that the values of the three primary colors in the diopter are almost the same, but in the infrared light region Erroneous correction is performed because the spectral distributions are significantly different.

Therefore, the present invention solves the above-described problems, and provides a colorimetric device for a camera that accurately measures a spectral distribution with a simple configuration regardless of the color of a subject or the type of a light source. It is an object of the present invention to provide a camera ranging device that can accurately measure a distance using a spectral distribution measured by the device.

[Means and Actions for Solving the Problems] A colorimetric device for a camera according to the present invention includes a spectral optical system that receives subject light and performs color separation, and a barycentric position of a spectral distribution of a light beam color-separated by the spectral optical system. Wherein the spectral optical system is constituted by a prism, and color-separates subject light that has passed through a photographing lens of a camera, and the center of gravity detection sensor is constituted by a semiconductor position detecting element. Is done. Further, a distance measuring apparatus for a camera according to the present invention is characterized in that the distance measuring value is corrected using the position of the center of gravity of the spectral distribution detected by the color measuring apparatus.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to the drawings. FIG. 1 is an optical path diagram of a distance measuring device of a camera using a spectral distribution measured by a color measuring device according to a first embodiment of the present invention. The present invention is disclosed in Japanese Patent Application Laid-Open No. 52-95221. This is shown as an example used for the in-focus point detecting device.

In the figure, a subject image is formed on a field stop 2 by an image pickup optical system 1 and a condenser lens 3 is disposed near an image forming point together with the field stop 2. Goes straight through mirror 4 and goes to pupil mask 6
And an optical path reflected by the mirror 4 and reaching the collimator lens 7. The pupil mask 6 limits the light beam from the imaging optical system 1, and the restricted light beam is re-imaged on the image detection sensor 10 by the separator lenses 5a and 5b. The above is the schematic configuration of the AF unit.

Next, an optical system for detecting a correction value of a distance measurement value will be described.
This optical system consists of collimator lens 7, slit 8, prism
9, a center of gravity detection sensor 11. The center-of-gravity detection sensor 11 is formed by a well-known semiconductor position detector (hereinafter abbreviated as PSD), and a ratio of photocurrents output from both ends of the PSD in accordance with an imaging position of a light beam applied to the PSD. , The center of gravity of the imaging point is obtained, and the center of gravity of the spectral distribution of the subject image can be obtained from the position of the center of gravity.

The light whose optical path is split by the half mirror 4 enters the collimator lens 7. The collimator lens 7 converts the light into parallel light and enters the slit 8. The slit 8 selects parallel light parallel to the optical axis and forms a thin light beam in order to increase the detection accuracy of the center-of-gravity detection sensor 11. The light beam that has passed through the slit 8 is
And the center of gravity detection sensor 11 detects the position of the center of gravity of the spectral distribution. Therefore, if the spectral sensitivity distributions of the image detection sensor 10 and the center of gravity detection sensor 11 are matched, the image detection sensor 10
And the correction value based on the signal detected by the center-of-gravity detection sensor 11 easily corresponds to 1: 1.

Next, the operation of the first embodiment configured as described above will be described.

Field stop 2 and condenser lens 3 by imaging optical system 1
Is relayed by the pupil mask 6 and the separator lenses 5a and 5b, and re-images on the image detection sensor 10. The defocus amount is detected by a defocus amount detection unit (not shown) based on the video signal output from the image detection sensor 10 by re-imaging on the image detection sensor 10. Although many defocus amount detecting means have been proposed, each of which has a slightly different configuration and operation, this is not essential in the present invention, and a detailed description thereof will be omitted.

The light beam whose optical path has been split by the half mirror 4 becomes parallel light by the collimator lens 7. The parallel light travels in various directions from various positions of the collimator lens 7 depending on the pupil position of the imaging optical system 1 and the height of the image formed by the imaging optical system 1. Only rays with a small image height parallel to the axis are selected. At this time, since the light beam has the width of the slit 8, the narrower the width of the slit 8, the higher the spectral accuracy of the prism 9 becomes. A light beam parallel to the optical axis is selected by the slit 8, separated by the prism 9, and detected by the center of gravity detection sensor 11 based on the wavelength at which the image detection sensor 10 feels the strongest or the video signal output from the sensor 10. The main wavelength of the detected value can be detected.

As shown in FIG. 6, the correction method is performed by using a graph, a table, a relational expression, an approximate expression, or the like showing the relationship between the wavelength and the correction amount. Further, the field image height selected by the slit 8 is not necessarily limited to the central portion, but may be set to an arbitrary peripheral image height position where spectral measurement is to be performed. Furthermore, the position of the image height may be changed using a physical stop using liquid crystal, PLZT, or the like, or using a stop whose position is variable in the direction perpendicular to the optical axis.

According to the first embodiment, since the spectral distribution of the detected image can be measured, it is hardly affected by the color of the image, and the defocus amount can be reliably detected. If a plurality of slits 8 are provided in the optical axis direction and the prism 9 is constituted by a spectroscope using a diffraction grating or the like,
Detection accuracy can be further improved. In addition, if a configuration is adopted in which a diffusion plate is provided, it is possible to determine the center of gravity of the spectral distribution of the entire image for which AF detection is performed, thereby making it possible to further reduce the influence of the color of the image.

As described above, since the correction is performed based on the center of gravity of the spectral distribution of the image, it is possible to cope with a light source having many types of spectral distributions and to cope with a wide range of spectral reflection distributions of an object.

FIG. 2 is an optical path diagram of a distance measuring device of a camera using a spectral distribution measured by a color measuring device according to a second embodiment of the present invention. In the figure, the configuration of the AF detection unit is the same as that of the first embodiment.
Although substantially the same as that of the embodiment, a major difference is that a mirror arranged on a portion of a light beam not used for re-imaging on a pupil mask 6 instead of the half mirror 4 for dividing an optical path into a system for detecting a spectral distribution. The point is that a part of the image light at 12 is guided to a system for detecting a spectral distribution.

The light reflected by the mirror 12 becomes parallel light by the collimator lens 7, is split by the prism 9, and the center of gravity of the spectral distribution is detected by the center of gravity detection sensor 11. At this time, although not shown, one or a plurality of slits may be inserted in the optical axis direction or a slit for peripheral image height may be inserted as in the first embodiment. In addition, it goes without saying that a system in which a diffusion plate is inserted or a spectroscope using a diffraction grating or the like may be used. Needless to say, the mirror 12 may be provided with power to serve as a reflective convex lens or a concave lens.

Next, the operation of the second embodiment configured as described above will be described. The light flux formed by the imaging optical system 1 is limited in image by the field stop 2, and is condensed on the pupil mask 6 by the condenser lens 3. The light beam transmitted through the pupil mask 6 is re-imaged on the image detection sensor 10 by the separator lens 5.

Except for the light that is re-imaged on the image detection sensor 10, of the light flux condensed on the pupil mask 6, the mirror 12 disposed in the vicinity of the pupil mask 6 is used to collimate the anti-beam that is not related to re-imaging. The light is reflected to the lens 7. Parallel light is formed by the collimator lens 7, the light is separated by the prism 9, and the center of gravity of the spectral distribution is obtained by the center of gravity detection sensor 11.

In the first embodiment, the slit 8 is inserted before the prism 9. However, in the second embodiment, the pupil position of the imaging optical system is limited by the size of the mirror 12. If the direction of the parallel light is determined only by the height of the image to be formed and is configured to be substantially parallel to the optical axis, the slit 8 can be omitted in the second embodiment.

According to the second embodiment, the position of the center of gravity of the spectral distribution can be obtained by using the light flux passing through the pupil mask 6 except for the light that forms an image on the image detection sensor 10. The image on 10 does not darken.

Further, since the optical system for obtaining the position of the center of gravity of the spectral distribution can be a reduced optical system, the amount of light projected on the center of gravity detection sensor 11 can be increased. Furthermore, if the narrow direction of the field stop 2 is matched with the direction for spectral detection, the detection accuracy can be further improved. Furthermore, since the entire image is viewed, errors due to the image are reduced.

FIG. 3 is an optical path diagram of a distance measuring apparatus showing a third embodiment of the present invention. In the third embodiment, the imaging optical system 1, the field stop
The condenser lens 3, the separator lens 5, and the pupil mask 6 are the same as those in the first and second embodiments, but the sensor unit 13 including the image detection sensor 10 is different from each of the above embodiments.

4 (A) and 4 (B) and FIGS. 5 (A) and 5 (B) show the detailed configuration of the sensor unit 13. FIG. FIG. 4A is a cross-sectional view of the sensor unit 13 shown in FIG. Fig. 3,
In FIG. 4A, an image is formed on the image detection sensor 133 by the separator lens 5. Sensor window glass 132
Is a light incident portion protecting glass of a package in which the image detection sensor 133 and the center of gravity detection sensor 134 are stored, and a mask 131 for blocking unnecessary light flux is disposed thereon.

A portion 141 of the mask 131 in a portion of the image that does not overlap with the image detection sensor 133 is opened in a slit shape, and the thickness of the glass of the sensor window 132 thereunder is changed into a wedge shape, so that a prism 142 is formed. It has become. The center of gravity of the spectral distribution of the light separated by the prism 142 is detected by the center of gravity detection sensor 134. The positional relationship between the image detection sensor 133 and the center-of-gravity detection sensor 134 is as shown in FIG. 4B, as viewed from the separator lens 5 side in FIG. In addition, as shown in FIGS. 5 (A) and 5 (B), the sign of each member in FIG. 4 is added with a suffix “a”, and the direction of detection of the center of gravity of the spectrum may be rotated by 90 °. It is.

Next, the operation of the third embodiment configured as described above will be described. The third embodiment utilizes the fact that the spectral distribution of a subject is macroscopically substantially the same when comparing parts close to the subject. The images near the image detection sensors 133 and 133a are passed through narrow slits in the longitudinal direction of the sensors, and the center of gravity detection sensors 134 and 13 are used.
Focus on 4a. Since the slit is near the image plane, a thin linear image appears on the center-of-gravity detection sensors 134 and 134a. However, since the thickness of the sensor window glass 132, 132a changes in the directions of arrows A and B shown in FIGS. 4 (B) and 5 (B), a spectral band is formed in that direction. Therefore, the center of gravity detection sensor 13
The center-of-gravity signal integrated in the direction perpendicular to the directions of arrows A and B of 4,134a can be detected.

In addition, a mask is used in a mold that matches the configuration of the first and second embodiments.
An optical system up to the collimator lens 7 of the first and second embodiments may be provided on the slit portions 131 and 131a.

According to the third embodiment, since the sensor can be constituted by one chip, the spectral sensitivity can be easily adjusted. Further, since the number of optical systems is small, the whole module can be downsized. Furthermore, since the parts are integrated, there is an effect that it is easy to make.

[Effects of the Invention] As described above, according to the present invention, the spectral distribution can be measured with a simple configuration, and furthermore, if the colorimetric device of the present invention is applied to a distance measuring device, the result of the distance measurement will be obtained. Even in a distance measuring optical system in which an error occurs depending on the wavelength of the light to be measured, since the wavelength component of the measuring light can be measured, the correction can be performed. Also, since the method of measuring the wavelength component of the measurement light is a method of detecting the center of gravity of the spectral distribution, for example, a large number of measurement filters such as a fluorescent lamp of a light bulb color or a sodium lamp, or a yellow subject under a fluorescent lamp. As compared with the conventional method that requires a device and an element, the detection can be performed by one detection sensor, thereby enabling a small distance measuring device with few errors. Also, since the usable spectral range of the apparatus is widened, a number of remarkable effects such as a higher sensitivity apparatus can be achieved.

[Brief description of the drawings]

FIG. 1 is an optical path diagram of a distance measuring device showing a first embodiment of the present invention, FIG. 2 is an optical path diagram of a distance measuring device showing a second embodiment of the present invention, and FIG. 4 (A) and 4 (B) show an essential part of the sensor unit in FIG. 3; FIG. 4 (A) is a cross-sectional view thereof; FIG. 4 (B) is a plan view of the sensor in FIG. 4 (A), and FIGS. 5 (A) and 5 (B) show the directions of detecting the centroid of the spectrum in FIGS. 4 (A) and 4 (B). FIG. 6 is a cross-sectional view and a plan view of the sensor rotated by an angle, and FIG. 6 is a characteristic diagram showing a correction value for the wavelength of reflected light.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-168613 (JP, A) JP-A-58-86504 (JP, A) JP-A-64-9326 (JP, A) JP-A-62 174710 (JP, A) JP-A-63-295935 (JP, A) JP-A-64-44407 (JP, U) JP-A-61-197775 (JP, U) (58) Fields investigated (Int. ^6, DB name) G01C 3/00 - 3/32 G01J 3/00 - 3/52 G02B 7/00 - 7/40 G01B 11/00 - 11/30

Claims (5)

(57) [Claims] 1. A spectral optical system that receives subject light and performs color separation, and a center-of-gravity detection sensor that detects a center of gravity of a spectral distribution of a light beam color-separated by the spectral optical system. Colorimeter of the camera to be used. 2. The colorimetric device for a camera according to claim 1, wherein said spectral optical system comprises a prism. 3. The colorimetric device for a camera according to claim 1, wherein the spectral optical system separates the subject light that has passed through a photographic lens of the camera. 4. The colorimetric device for a camera according to claim 1, wherein said center-of-gravity detecting sensor comprises a semiconductor position detecting element. 5. A distance measuring device for a camera, wherein a distance measurement value is corrected using a center of gravity of a spectral distribution detected by the color measuring device according to claim 1. .