JP2692987B2 - Distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a so-called active system that measures the distance to a subject by projecting a light flux from a light source to the subject side and receiving a reflected light flux from the subject. Type distance measuring device.

[Prior Art] Conventionally, various so-called active distance measuring devices have been known which perform distance measurement to a subject by projecting a light flux from a light source to the subject side and receiving a reflected light flux from the subject. There is. Further, recently, many techniques called wide-field distance measurement or multi-point distance measurement have been proposed in which light is projected onto a wide area on the object side and information of the wide distance-measurement field is utilized for the distance measurement result.

FIG. 2 shows a general optical perspective view of such a conventional example. 4 is a light projecting lens, 5 is a light receiving lens, and 6a to 6c are, for example,
Light sources such as iRED (infrared light emitting diode), 7a to 7c are, for example, PSDs (Position Sensitive Decoders) corresponding to the above light sources.
vice) and the like, and 8a to 8c respectively represent the subject. In this example, there are three pairs of light emitting and light receiving elements, and three points that are separated by a predetermined angle of view are each subjected to known triangulation. Then, for example, even when the main subject 8b is not located at the center of the angle of view, the distance to the subject 8a, which is another point, can be measured, so that appropriate distance measurement can be performed while preventing so-called loose hollow.

[Problems to be Solved by the Invention] However, since such a distance measuring system usually has an aperture for distance measuring at a position different from the finder window, parallax between the distance measuring field of view and the finder is particularly great in close-up photography. growing. In particular, when the parallax of the finder is corrected for the taking lens at the time of close-up photographing, the parallax between the distance measurement field of view and the finder becomes more remarkable because the distance measuring system is usually fixed.
3 and 4 are diagrams for explaining such a situation. In FIG. 3, 1 is a taking lens, 4 is a light projecting lens, 5 is a light receiving lens, 2 is a finder, and 2'is a finder for close-up photography. Shows the objective lens position. In Fig. 4, 10 is the finder field frame, 11 is the distance measuring frame within the finder, 12 is the distance measuring field when there is no parallax between the distance measuring system and the finder, and 12 'is for close-up photography. Represents the distance measuring field of view.

If the finder objective lens is moved as shown in FIG. 2'for parallax correction between the photographic lens and the finder at the time of close-up photography, the parallax between the photographic lens and the finder with respect to the near object is eliminated, but the light projection is performed. Since the lens is fixed, it illuminates the upper left corner of the near object, and the distance measuring point is greatly displaced from the inside of the distance measuring frame to the upper left corner as shown at 12 'in FIG.

An object of the present invention is to efficiently solve the parallax between the distance measuring field and the finder field during close-up photography, which is a drawback of the conventional example described above, by fully utilizing the feature of the distance measuring device called multi-point distance measuring. To do.

[Means (and Action) for Solving the Problem] Therefore, according to the present invention, a light flux from a light source divided into a plurality of directions is provided in a plurality of directions on the subject side by an external finder and a light projecting system arranged outside the photographing lens. Within a predetermined distance in a distance measuring device that measures the distance to the subject by projecting a light beam to the subject and receiving a reflected light beam from the subject by a light receiving system arranged at a predetermined base line distance from the light projecting system. Distance measurement for a certain subject is performed by performing visual field correction to the external finder, projecting a selected light beam to the certain subject, and receiving reflected light to the projected light beam. It is in the distance device.

[Embodiment] FIG. 1 is a perspective view showing an embodiment of the present invention, in which 1 is a taking lens, 4 is a light projecting lens having a main lens portion 4a and a sub lens portion 4b for close-up photography, 5 is a light-receiving lens, 6a-
6c is a light source such as iRED arranged in parallel in the length direction of the base line to project light in the horizontal direction. Reference numerals 7a to 7c are light receiving elements, such as PSDs, respectively corresponding to the light sources 6a to 6c, and are also arranged in parallel in the horizontal direction. 7
d is a light-receiving element used for close-up photography.
It is provided above. Further, 2 is a finder, and 3 is a subject at the time of close-up photography. For example, by bringing the finder 2 closer to the optical axis direction of the taking lens at the time of close-up photography, parallax correction can be performed with respect to the optical axis of the taking lens. There is.

The main lens portion 4a of the light projecting lens 4 is adjusted for parallax with respect to the finder 2 in the normal state (before the close-up photographing state), and the light beams from the light sources 6a to 6c project toward the subject through the main lens portion 4a. Light is emitted and the above-described multi-point distance measurement is performed. In the case of normal distance measurement, distance measurement calculation based on the light receiving element 7d is off. On the other hand, when the subject is at a close distance, that is, when distance measurement is performed on a short-distance object, the finder 2 performs parallax correction on the taking lens 1 as shown in FIG. The distance measurement calculation is started. Further, the light sources 6b and 6c are prohibited from emitting light. Then, the light projection is performed by directing the light flux from the light source 6a toward the near subject through the sub lens portion 4b. Then, the reflected light from the subject 3 at a short distance is guided to the light receiving element 7d for close-up photography through the light receiving lens 5, and the subject 3 is measured according to a known triangulation algorithm. The mode switching at the time of close-up shooting may be automatically switched when the distance to the main subject is determined to be within a predetermined distance to some extent as a result of the distance measurement calculation performed through the main lens unit 4a. It may be forcedly switched by an external input means such as a macro mode switch.

The specific configuration of the light projecting lens 4 is shown in FIG. FIG. 5 (a) is a side view of the projection lens, and FIG. 5 (b).
Is a diagram showing a state where the optical axes of the respective lenses of the main lens portion and the sub lens portion are displaced, and FIG. 5 (c) is a front view showing the shape of the light projecting lens. In the figure, La and Lb are the optical axes of the lens parts 4a and 4b, respectively.
Similarly, a and Ob respectively represent the optical axis positions of the lens portions 4a and 4b. In order to correct parallax during close-up photography, the optical axis Ob of the sub-lens portion 4b is set below the optical axis Oa of the main lens portion when the light projection point is above the photographing lens as in this embodiment. ,
The light beam crosses the photographing optical axis at a closer distance.
In fact, the position of the optical axis Ob is provided obliquely below the surface lens portion optical axis Oa as shown in FIG. 5 (B). Lens part 4 in the figure
Reference numerals a ′ and 4b ′ represent lenses whose optical axis positions are Oa and Ob, respectively, and reference numerals 4a and 4b represent actual apertures within a range surrounded by a chain double-dashed line. FIG. 5C is an actual one in which only the shape of the lens portion is extracted. The optical axes of the main lens part and the sub lens part are shifted not only in the vertical direction but also in the horizontal direction. This is because the light source using the sub lens part is not at the center light source 6b shown in FIG. The main reason is to use the light source 6a located. However, by providing the sub-lens part for close-up shooting integrally with the main lens part in the same direction as the arrangement direction of the light sources used for close-up shooting in this way,
Also, by setting the light emitting element for close-up photography to the position where the sub lens part is closer, the edge of the sub lens part can be removed,
Even if the main lens portion is large, it is possible to further provide a sub lens portion. Since the main lens section is for projecting light onto a subject at a normal distance, a larger aperture is desirable because the projection power is increased and the projection light flux reaches a longer distance.

In the present embodiment, each light source emits light in time series, and other light sources are turned off during light emission of the light source 6a shown in FIG. 1 during close-up photography to avoid extra stray light. Is configured. It is desirable that the sub-lens portion is extended by an appropriate amount as compared with the main lens portion. In addition, it is desirable that the main lens portion and the sub lens portion are integrally formed in order to reduce the size.

Other Embodiments In addition to the light projecting system shown in FIG. 1, for example, a sub lens part is provided in the direction opposite to the main lens part 4a of the light projecting lens in FIG. The light source 6c in the figure may be used during close-up photography.

Further, as shown in FIG. 6, by providing a plurality of sub-lens parts,
It may be possible to measure the distance to a finer object or a closer object. In the figure, 4c is a further sub lens part, 3 '.
Indicates a subject which is closer to the subject 3 and 7e indicates a light receiving element used for distance measurement of the subject 3 ', and other reference numerals are the same as those described above. In this case, it is desirable that the parallax of the viewfinder be corrected in two stages for close-up shooting and further close-up shooting.

The method of correcting the parallax of the finder is not limited to the movement of the objective lens as shown in FIG. 3, but may be a mechanical or electrical movement of the field frame.

[Effects of the Invention] As described above, according to the present invention, by selectively and effectively utilizing a light source for distance measurement at another store, distance measurement is performed with less energy loss and parallax even at close range shooting as much as possible. Can be done.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a view for explaining conventional multi-point distance measurement, FIG. 3 is a view for explaining finder parallax correction, and FIG. FIG. 5 is a diagram for explaining distance measuring parallax at the time of finder parallax correction, FIG. 5 is a diagram showing a light projecting lens according to the present invention, and FIG. 6 is a perspective view showing another embodiment of the present invention. 1 …… Shooting lens 2 …… Finder 4 …… Emitting lens 4a …… Ejecting lens main lens section 4b, 4c …… Emitting lens sub-lens section 5 …… Receiving lens 6a to 6c …… Light source 7a to 7e… …Light receiving element

Claims (2)

(57) [Claims] 1. A light projecting system arranged outside a photographing lens projects light beams from a plurality of divided light sources in a plurality of directions on the object side, and reflects light beams reflected from the object to the light projecting system. And a distance measuring device for measuring the distance to the object by receiving light by a light receiving system arranged at a predetermined base line distance, the light projecting lenses of the light projecting system have different focal lengths but different optical axes. When the normal distance measurement is performed by using at least the first and second lens units, the distance measurement is performed by projecting light from the plurality of light sources through the first lens unit. When it is determined that the distance to the subject is within the predetermined distance, the distance measurement is performed based on the light flux from the predetermined light source selected from the plurality of light sources and the light projection light flux that has passed through the second lens unit. Distance measuring device characterized by that. 2. A light projecting system arranged outside the photographing lens projects light beams from a plurality of divided light sources in a plurality of directions on the object side, and reflects light beams from the object to the light projecting system. In a distance measuring device which is arranged with a predetermined base line length, and which receives light by a plurality of light receiving elements corresponding to each of the light sources to measure a distance to a subject, the light projecting lenses of the light projecting system are respectively focused. It is composed of at least first and second lens portions having substantially equal distances but different optical axes, and for a subject having a predetermined object distance or more, light from the plurality of light sources is passed through the first lens portion. The light is emitted, and distance measurement is performed based on the outputs of the plurality of light receiving elements. For a subject within a predetermined object distance, light from at least one light source of the plurality of light sources is used as a second lens. Light is emitted through the light receiving section and is at a position different from that of the plurality of light receiving elements. Distance measuring apparatus which is characterized in that the distance measurement based on the output of the light receiving element provided on.