JPS58174808A - Distance measuring device - Google Patents

Abstract

PURPOSE:To improve detecting accuracy, by arranging the direction of the minimum length of a noncircular light receiving lens along the direction perpendicular to a boundary plane of two regions, which are obtained by dividing an output. CONSTITUTION:The device comprises, e.g. an infrared ray light emitting diode, a laser diode, or the like. A light projecting element 1 forms a light projecting spot image through a light projecting lens 2 constituting a image forming optical system. When luminous flux projected form the light projecting element 1 hits an object, diffused reflection occurs. The light projecting spot image on the object is formed on a light receiving element 3 through the light receiving lens 4. the light receiving element 3 is devided into the two regions, and the outputs are taken out of the two regions. The image forming positions are changed when the distances to the object changes to l1, l2, or l3. Information indicating the distance to the object is obtained from the position, where the light projecting spot image on the object is formed on the light receiving element.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distance measuring device, particularly a distance measuring device in an automatic focusing device, and features a means for increasing detection accuracy in a light receiving element.

Many proposals have been made regarding distance measuring devices for automatic focusing devices for cameras, and most of them are based on the principle of triangulation. For example,
Light projection optical system and light reception (1) Optical systems are provided with their yt and @ separated from each other by the baseline length. When the light beam emitted from the light projecting element in the light projecting optical system hits the object to be measured, it is diffusely reflected, and a projected spot image on the object to be measured is formed on the light receiving element. Since this position 11 changes as the distance to the object to be measured changes, this imaging position provides information indicating the distance to the object to be measured. In the case of a photographic device, the lens group that performs the focusing operation in the photographic optical system and the above-mentioned light receiving element (and also the light emitting element) are linked by a cam mechanism etc. This makes it possible to detect the distance to the subject (object) and automatically adjust the focus of the photographic optical system. If the above-mentioned light-receiving element is configured to be able to extract the output by dividing it into two regions, the in-focus state is detected based on the difference in the output of the two regions, so the peak f-direction in the light-receiving element is detected. 1. The present invention provides a distance measuring device (2) in which the light receiving element described above is capable of outputting output in two areas. The purpose is to further improve distance detection accuracy by the configuration and arrangement of the image optical system.

In summary, the present invention provides a light emitting element, a light receiving element that can be divided into two areas and outputting an output, and a distance measuring device that uses the above light emitting element and light receiving element to reach an object to be measured. comprising means for providing information indicating distance and a lens for the light receiving element; the lens for the light receiving element is non-circular;
The distance measuring device is characterized in that the direction of its minimum length is arranged along a direction perpendicular to the boundary surface of the two regions.

The light-receiving element can be divided into two regions E7 and output can be taken out, or the light-receiving element can be divided into two regions and output can be taken out from each region, or the two light-receiving elements can be placed close to each other. Various embodiments of the arrangement are possible.

- Also, in carrying out the present invention, the two regions of the light receiving element are arranged such that the direction perpendicular to the boundary between them is parallel to the direction of the minimum length of the lens. It is possible to place

A specific example embodying the present invention will be described with reference to daytime drawings. In the following description, the tf! j
The imitation will be described in conjunction with FIGS. 1-4 and 8 as a king. .

FIG. 1 shows an example of an automatic focus adjustment device to which the present invention is applied. In the figure, reference numeral 1 denotes a light projecting element, which is comprised of, for example, an infrared light emitting diode (IRKD) or a laser diode (LD). Reference numeral 2 denotes a light projection lens constituting the imaging optical system, and the light projection element 1 is projected by this lens, and in this example, a light spot image is projected toward the object side, and generally toward the object to be measured. form. When the light beam emitted from the light projecting element 1 hits the subject, it is diffusely reflected, and a projected light spot image on the subject surface is formed on the light receiving element 6 by the light receiving lens 4. The light receiving element 6 may be, for example, a photodiode which is divided into two regions and can output an output from each region n, or a photodiode having two light receiving elements arranged close to each other. There are various aspects. The above image forming position is (4) when the subject distance is l4, 12, . 1, the distance to the subject is given by the position where the projected spot image on the subject is formed on the light-receiving element.

In the example of diagram M1, if the two areas of the light-receiving element 6 are called the front area and the B area, the difference between the respective outputs M - B = Q
The structure is such that the position of the light receiving element is changed so that the following occurs. In the figure, 5 is a lens group that performs a focusing operation in the photographic lens system, 6 is an image pickup tube, and the light emitting element 1, the light receiving element 3, and the lens group 5 are connected by a force^ mechanism, for example, as shown in the figure. It is linked. In this way, it is possible to detect the distance to the subject and automatically adjust the focus.Also, by emitting light from the light emitting element continuously or in pulses at short intervals, even moving subjects can be continuously focused. It becomes possible to make adjustments.

There are many factors that affect the detection accuracy in this type of device, but among these, if we consider the means related to the light receiving optical system, In order to improve the accuracy, it is desirable that the blur of the image be small and the image be sharp in the direction in which the surface area and the B area are lined up. Generally speaking, including when the light receiving element has a curved surface, it is desirable that the image be sharp with little blur in the direction perpendicular to the boundary surface between the surface area and the B area of the light receiving element. . Therefore, in this invention, the shape and arrangement of the light receiving lens 4 are
The mode shown in the figure is used. That is, the photodetector is arranged vertically parallel to a line (baseline in this example) connecting the light emitting and receiving elements.

In this case, as shown in FIG. ) is desirable.

The reason is as follows. Figure 3 (M) and (E)
), the light beam that enters the receiving lens in the long horizontal direction) is blurred by a small amount of δa, whereas the light beam that enters the receiving lens in the long vertical direction (b) is blurred at the same distance. The image is blurred by the diameter of ab. In other words, the spot spread is 9
Since δa>ab, it is necessary to reduce the blurring of the image in the direction of 5B and the image must be sharp in order to obtain a highly accurate MuB reconnaissance signal taken out by the light-receiving element 6. There is.

Therefore, the configuration shown in FIG. 2 will be adopted.

Similarly, the light projecting lens 2 has a shape in which the horizontal direction a is longer than the vertical direction, as shown in FIGS. It is arranged parallel to the line (base M1).

Next, the reason why the two regions of the light receiving element 6 are arranged side by side in the base line direction will be explained.

As shown in FIGS. 4(M) and 4(B), if the amount of movement of the projected spot image on the light receiving element 3 is a, in order to improve the detection accuracy, it must be moved in the direction of 4(B) (FIG. 4(B)). m)) is most preferred. On the other hand, in the case shown in FIG. 3B, detection is essentially performed at b (b<a), which reduces the detection accuracy accordingly. (7) In order to obtain the movement relationship shown in the same figure (m), the arrangement of the light-receiving elements was such that area A and area B were lined up in the direction of the baseline, and the boundaries between the two areas were generally plane. It is desirable to make it perpendicular to the direction of the baseline.

The scanning direction of the light emitting/receiving optical system that is intended to be implemented in conjunction with the present invention will now be described.

Returning to Fig. 1, if the optical axes of the photographing lens 5, the light emitting lens 2, and the light receiving lens 4 are on the same half plane, and the focal lengths of the light emitting lens and the light receiving lens are the same, then By moving the light emitting element 1 and the light receiving element 6 by the same distance in opposite directions within the above half plane, the position of the ranging field of view can always be maintained at the center of the screen, as shown in Fig. 5. . In FIG. 5, a solid line 19 indicates positions If and tl-, respectively, when the focal length of the photographing lens is short, and a double-dotted chain pass 20 indicates positions when it is long.

However, as shown in FIG. 6, in an actual camera, due to the arrangement of other operating members, such as manual zooming operating members, (8) the photographing lens 5, the light emitting lens 2, and the light receiving lens. It is rather rare that the optical axes of the three lenses exist on the same plane, and for example, as shown in the figure, the light projecting lens 2 and the light receiving lens 4 must be arranged offset from the center of the photographing lens 5. In other words, FIGS. 6(M) and 6(B) show an example in which an automatic focus adjustment device using triangulation is incorporated into an actual 8 mm camera or video camera, where 14 is for manual zooming. It is an operation bar, and "" indicates its rotation range.The user, for example, grips the grip 12 with his right hand,
Since the trigger button 13 is operated and the manual zooming operation is performed with the left hand, the light emitting lens 2 and the light receiving lens 4 are placed in the position shown in FIG. It is desirable to arrange the camera lens 5 so that it is offset from the center of the photographic lens 5.However, with this arrangement, it is difficult to perform p focusing by scanning only one of the light emitting and receiving optical systems, for example, the light receiving system. The distance measurement position in the finder screen, that is, position f of the projected light spot image position (9) is as shown in Fig. 7.In other words, at a certain distance from the entire screen 7, the distance measurement position spot image) is 8
-1, for example, when the subject is at a distance corresponding to 8 to 1, the distance measurement position changes to 9-1, and when the subject is far away, it changes to 10-1. . Of course, the above relationship changes depending on the arrangement of the light emitting and receiving elements. Furthermore, if this photographing lens thread is a zoom lens, the size of the projected light spot within the screen will become multiple depending on the focal length.
and 10-2 tablespoons. Further, as can be seen from FIG. 7, the change in the position of the light projection slit 11 occurs not in the X direction or in the X direction, but along the sun direction tilted at a certain angle 0 from the X axis. According to the inventor's analysis, this current order is caused by arranging the above-mentioned light transmitting and receiving optical system offset from the center of the photographing lens. As a result, a displacement component in the χ axis direction is generated, and the combination of the two causes a displacement in the six directions shown in the figure. Even in the offset arrangement as shown in FIG. 6(m), if the light emitting/receiving optical system is scanned symmetrically, the displacement of the distance measurement position will appear VC only in the Y-axis direction.

Here, as described above, the photographing lens 5, the light emitting lens 2
Even if the optical axes of the three lenses and the light receiving lens 4 are not on the same plane, it eliminates the deviation of the distance measurement field of view, and furthermore, it
It is desirable to keep Jfr always at the center of the 1illii plane. This rounding can be done by simultaneously moving one or both of the optical axes of the light emitting optical system or the light receiving optical system with the axis of rotation perpendicular to the straight line connecting the optical axis and the optical axis of the photographing optical system. An example of rotation will be specifically explained. FIG. 8 shows the scanning direction of the light emitting/receiving element to achieve this purpose. are arranged in a direction perpendicular to a straight line connecting the centers of Generally speaking (11), if the direction of rotation 41111B is perpendicular to the straight line connecting the optical axis of the light emitting lens and the optical axis of the photographing lens, then
This achieves the above objectives.

Similarly, the direction of rotation l11111B of the light receiving element holder 17 is arranged in the direction VC perpendicular to the straight line connecting the optical axis of the light receiving lens and the optical axis of the photographing lens. The light projecting element and the light receiving element are rotated about rotational axes 16 and 17, respectively, and scanning is performed in a direction perpendicular to the plane of the paper in FIG. 8. According to this configuration, since the scanning direction of the light emitting element and the light receiving element is directed toward the center of the photographing lens, the optical axes of the photographing lens, the light emitting lens, and the light receiving lens are on the same plane. To make it possible to always position a distance measurement field of view at the center of a screen even when there is no field of view. The condition of the finder screen in this case is as shown in Figure 5, and even if the optical axes of the three optical systems are not on the same plane, the distance measurement field of view can always be placed at the center of the screen. can. In the case where only either the light emitting element or the light receiving element is rotated in the same manner as described above (12), the distance measurement field of view is displaced only in the direction of the X axis in FIG. There is no effect of deviation of the optical axis, that is, offset arrangement. Moreover, if the angle between the direction of displacement S and X@ in FIG. 7 is θ, then the displacement capacity in this case is reduced to D OOaθ when 1 of the displacement in FIG. 7 is D.

In the specific examples shown in Figures 1 and 8, the focal lengths of the emitter lens and the receiver lens are the same, but if they are different, the focal lengths of the emitter element and the receiver element may be adjusted to match the respective focal lengths. A similar effect can be achieved by drawing a trajectory.

As shown in FIG. 8, the arrangement of the light-receiving element described above is arranged in the direction B even when the light-receiving element is rotated toward the optical axis of the photographic lens.

It is arranged not in the direction that connects the optical axis of the light-receiving lens and the optical axis of the photographic lens, but in the direction that connects the optical axis of the light-receiving lens and the optical axis of the light-emitting lens, that is, in the direction of the base line.

(16) Since the present invention has the above-described configuration and operation, the lens for the light receiving element is non-circular, and the direction of its minimum length is along the direction perpendicular to the boundary surface between the two areas of the light receiving element. Based on the arrangement, image blurring can be minimized in this direction, and the precision of the difference signal extracted from the two regions can be improved, and the distance detection precision can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an automatic focus adjustment device to which the present invention is applied, FIG. 2 is a diagram showing a light projecting lens and a light receiving lens and their arrangement according to the present invention, and FIG.
and (I) are explanatory diagrams of the action of the device in Fig. 2, and Fig. 4 (M)
and (B) is a front view showing the arrangement of the two areas of the light receiving element, Fig. 5 is a diagram showing the distance measurement field of view position when using the device in Fig. 1, and Fig. 6 (M) is a diagram showing the automatic focus adjustment of the camera. A front view showing an example of how the device is assembled, M6 (B), is a front view showing an example of incorporating the device.
Fig. 7 is a diagram showing the distance measurement field of view position when using the devices in Figs.
14) is a schematic diagram showing the scanning direction. In the figure 1...Light emitting element 2...Light emitting lens 6...Light receiving element 4...Light receiving lens 5...Lens group that performs focusing operation among the photographic lenses 15...Light emitting element holder 16... Co-rotation axis of the light emitting element 17... Light receiving element holder 18... Rotation axis of the light receiving element, B... Area divided into two parts of the light receiving element (15) Horse? 2 rOn Haku7mon X Suji B Akebono 48-

Claims (1)

[Claims] A light emitting element, a light receiving element whose output can be taken out by dividing it into two areas, and a distance to an object to be measured using the light emitting element and the light receiving element. means of giving information;
and a lens for the light-receiving element, and the lens for the light-receiving element is characterized by being non-circular, and the direction of its minimum length is arranged along a direction perpendicular to the interface between the two regions. distance measuring device.