JPH0377013A - Range-finding device - Google Patents

Abstract

PURPOSE:To allow one light projecting element and one photodetector to be used respectively and to reduce the cost of a device by adjusting the light projection angle of the flux of light beams with the aid of a light projection angle changing means. CONSTITUTION:Infrared rays projected from the light projecting element 1 is condensed by a light projecting lens 3 to irradiate an object 2 and the reflected light from the object 2 is received by the photodetector 4 through a light receiving lens 5. The light projection angle of the flux of light beams projected from the element 1 is changed by moving the lens 3 back and forth in a light projecting direction. The lens 3 is attached to a movable lens holder 6 so as to constitute the light projection angle changing means 17. By driving a motor 13, the holder 6 is moved back and forth in the light projecting direction. When the output of the element 4 is not obtained for the small light projection angle of the means 17 but obtained for the large one, a specified signal output means transmits a signal to lens driving means to move an image pickup lens to a usual focusing direction, then the image pickup lens is moved to a position where focusing direction, then the image pickup lens is moved to a position where focusing is performed in an infinity distance when the output of the element 5 is not obtained for any light projection angle of the means 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance measuring device for a camera that measures the distance to a subject by photoelectric means.

[Conventional technology]

In recent years, cameras have been developed that are equipped with an autofocus device that automatically controls focus adjustment of a photographic lens based on a signal obtained by distance measurement or focus detection using photoelectric means. An autofocus device includes a distance measuring device that measures the distance to a subject using photoelectric means, and a photographic lens drive device that moves a photographic lens to a focusing position. Distance measurement! There are triangulation methods in Lt, including passive methods and active methods.

An example of such an active distance measuring system is shown in FIG. 9. In the figure, infrared rays are emitted from a light emitting element 101 to a subject via a light emitting lens 102, and a light receiving element 103 separated from the light emitting element 101 by a predetermined baseline length passes through a light receiving lens 04. Light is being received. The amount of light received by the light receiving element 103 Ql, Q2. Q3
is output as a signal to the control means, and is calculated based on the baseline long day to measure the distance to the subject.

Here, the infrared rays projected from the light projecting element 101 are condensed by the light projecting lens 102 into a bundle of light rays. For this reason, when two people are lined up as subjects,
If the beam of light is projected between two people, it may pass through this space (so-called hollow) and may be projected onto a distant view between the two people. In this case, the distance measuring device will erroneously measure the distance to the distant view as the object distance, and the screen on which the two people, who are the objects, will be photographed will be out of focus.

Therefore, distance measurement ji If bl ! shown in FIG. ! proposed (Unexamined Japanese Patent Publication No. 1983)
-223734), in the figure, a plurality of light emitting elements 111 are arranged in parallel, and a plurality of light emitting elements 1
The infrared rays sequentially projected from 11 are reflected by a subject 112 and received by a plurality of light projecting elements 113. In this way, the light emitting element 111 and the light receiving element 1
13, even if one of the light beams from the light projecting element 111 falls through, the light beams from the other light projecting elements 111 will be reliably projected onto the subject, making it possible to accurately determine the distance to the subject. can be measured.

[Problem to be solved by the invention]

However, in such conventional distance measuring devices,
The light emitting element 111 and the light receiving element 11 are used to prevent the light from falling out.
Multiple 3 were installed. Here, these light emitting elements 1
11 and the light receiving element 113 are each expensive. Therefore, a distance measuring device using a plurality of these light emitting elements 111 and light receiving elements 113 has a high cost as a whole.

On the other hand, in order for the light-receiving element 113 to receive the reflected infrared light emitted from the light-emitting element 111, the mounting precision for attaching the light-emitting element 111 and the light-receiving element 113 to the device must be increased. However, if the number of these components increases, the mounting accuracy must be made even stricter, the configuration for mounting becomes more complicated, and subsequent adjustment of the mounting becomes difficult. Furthermore, a plurality of light emitting elements 111
Since the light is emitted sequentially from the beginning, there is a problem in that the distance measurement time becomes long.

[Means to solve the problem]

In order to solve such problems, in the present invention,
a light projecting element that projects light onto a subject; a light projecting lens that collects the light projected from the light projecting element into a bundle of light rays; and a light projecting element that is arranged at a baseline length apart from the light projecting element, A distance measuring device includes a light receiving element that receives reflected light from a subject through a light receiving lens, and calculates a distance to the subject based on the output of the light receiving element. A first specific signal is generated when the output of the light projection angle converting means for adjusting and the light receiving element cannot be obtained for a narrow light projection angle of the light projection angle converting means, but is obtained at a wide light projection angle. and a specific signal output means for outputting a second specific signal when the output of the light receiving element is not obtained for any of the projection angles of the projection angle conversion means. This configuration is a specific signal output means.

[For production]

If the projection angle of the light beam from the light projection element is widened by the projection angle conversion means, it is possible to prevent the projection from falling through the lens. For this reason, only one expensive light emitting element and one light receiving element are required, and since only one light emitting element and one light receiving element are required, installation accuracy is not as strict as in the past, when multiple elements were installed.
The second configuration to be installed is also simplified, and subsequent adjustments to the installation are also easy. Furthermore, compared to the conventional case of sequentially emitting light from a plurality of light emitting elements, it is only necessary to emit light once from one light emitting element.

In addition, when the projection angle of the beam of light is set to a wide angle, the first specific signal is output from the specific signal output means to the lens driving means to move the photographing lens to the pan focus position. Alternatively, the second specific signal is output to move the photographing lens to a position where it is focused at an infinite distance.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings. 1 to 6 are diagrams showing a first embodiment of a distance measuring device according to the present invention.

First, the configuration will be explained.

In FIG. 1, the symbol l is a light emitting element (for example, an infrared light emitting diode) provided in the camera body,
This light projecting element 1 projects infrared light onto a subject 2. Further, a light projecting lens 3 is disposed in front of the light projecting element, and this light projecting lens 3 is for condensing the infrared rays projected from the light projecting element 1 into a bundle of light rays. be.

A light receiving element 4 (for example, PSD: Po5ttionSen
stive diode) is disposed to receive reflected light from the subject 2. Further, a light receiving lens 5 is disposed in front of the light receiving element 4 and focuses the reflected light onto the light receiving element 4.

Incidentally, the projection angle of the beam of light projected from the light projection element 1 can be changed by moving the projection lens 3 back and forth in the projection direction. Therefore, this projection angle conversion means 17 is used as the 21st! As shown in FIG. 1, the light projecting lens 3 is attached to a lens holder 6, and the lens holder 6 is placed on a base plate 7 so as to be movable in the light projecting direction. A pair of guides 118a and 8b are formed in the lens holder 6 in the light projection direction, and a pair of guide bins 9a and 9b implanted in the base plate 7 are fitted into the guide grooves 8a and 8b. Also, the lens holder 6 is long and thin! l! A driving groove 10 is formed, and a driving pin 12 eccentrically implanted in a disc 11 is loosely fitted into this driving groove 10. When the disc 11 is rotated by the motor 13, the lens holder 6 is guided by the guide bins 9a and 9b and moves back and forth in the light projection direction.

FIG. 3 is a block diagram of a control circuit installed in this distance measuring device. A beam of light with a narrow projection angle is projected from the light projecting element 1 toward the subject 2, and when the reflected light from the subject is received by the light receiving element 4, the distance calculation circuit ' The distance to the subject 2 is calculated by 1IJ14. Next, the object distance is outputted as a signal from the main control circuit 15 to the lens driving means 16.

When the light receiving element 4 does not receive reflected light, a signal is output from the main control circuit 15 to the projection angle conversion means 17, and the projection angle of the beam is widened by the projection angle conversion means I7. When the reflected light of this wide-angle beam is received by the light receiving element 4, a first specific signal is outputted from the specific signal output means 18 to the lens driving means 16. When the wide-angle light beam is not received by the light receiving element 4 as reflected light,
A second specific signal is output from the specific signal output means 18 to the lens driving means 16.

Next, the effect will be explained. The fourth ryJ is a flowchart showing the operating procedure of this distance measuring 11 position, and will be explained with reference to this flowchart.

First, an infrared beam is projected from the light projection element 1 toward the subject, but this bundle of light rays is converged by the light projection lens 3 (the projection angle is very narrow), and then the light is projected. Infrared rays will be reflected if the subject is not a distant view (F(+)),
When this reflected light is received by the light receiving element 4, normal distance measurement is performed (F(2)). That is, this amount of received light is converted into an electrical signal, and this electrical signal is amplified and the distance to the subject 2 is calculated by the distance calculation circuit 14.The calculated subject distance is sent as a signal from the main control circuit X5 to the lens driving means. 16, and moves the photographing lens to the in-focus position (F(3)).

On the other hand, even if the subject is not a distant view, if two people are standing side by side, the bundle of infrared rays projected from the light projecting element 1 will pass between the two people, as shown in Figure 5. In this case, the infrared rays are not reflected from the subject (F(1)). Therefore, a signal is output from the main control circuit wIJ15 to the projection angle conversion means 17, and the motor 13 is driven to change the projection lens. 3 as shown in FIG.
m, and widen the projection angle of the ray bundle (F(4)
), When the projection angle of the ray bundle is set to a wide angle, this ray bundle will be reflected from the subject without passing between the two people, unless the subject is in the distance (F(5)), Reflection When the light is received by the light receiving element 4, a first specific signal is outputted from the specific signal output means 18 to the lens driving means 16, and the photographic lens is placed in a pan focus position (also called a common focus position, from the foreground to the distant background). (F(6)).

Next, even if the projection angle of the ray bundle is wide-angle, if the subject is a distant view, no reflected light will return from this distant view (F
(5)) Therefore, the reflected light is not received by the light receiving element 4, and the specific signal output means 18 is transmitted to the lens driving means 16.
A second specific signal is output to , and the photographic lens is moved to a position where it is focused at an infinite distance (F(7)).

In this way, in order to prevent the light from falling out, the projection angle of the light beam from the light projecting element 1 is widened by the light projecting angle converting means 17, so that the expensive light projecting element 1 and light receiving element 4 each have a
In addition, since only one light emitting element 1 and one light receiving element 4 are required, the installation accuracy is less strict than in the past, which did not require multiple installations, and the configuration for installation is simpler, making it easier to install. It is also easy to make later adjustments. Furthermore, compared to the conventional case in which light is emitted sequentially from a plurality of light emitting elements, since it is only necessary to emit light once from one light emitting element 1, the distance measurement time can be shortened.

In addition, when the projection angle of the light beam is set to a wide angle, the first specific signal is output from the specific signal output means 18 to the lens driving means 16 to move the photographing lens to the pan focus position, or the second specific signal is outputted from the specific signal output means 18 to the lens driving means 16. Since a specific signal is output to move the photographing lens to a position where it can be focused at an infinite distance, the photographed screen does not become out of focus and remains within an acceptable range.

By the way, when a beam of light with a wide-angle projection angle is reflected by the subject 2, the light is received by the light-receiving element 4, compared to a case where the projection angle of the beam of light is a narrow angle and the subject is at the same position. The amount of reflected light received will decrease. Therefore, when the projection angle of the beam of light is set to a wide angle, the object distance may be calculated by correcting the amount of received light.

Next, a second embodiment of the distance measuring device according to the present invention will be described with reference to FIGS. 7 and 8. This example is the 7th Q! It
As shown in (a) and (b), in the center of the holder 21 there is a first light emitting element 21 (for example,
A second light emitting element 23 (same as above) whose light projection angle is wide from the beginning is provided on the outer periphery of the first light emitting element 23. Therefore, as shown in FIG. 8, the first light-emitting element 23 is used during normal distance measurement, and the second light-emitting element 23 is used when hollowing occurs.

In the first embodiment, the lens 3 is made movable, but the same effect can be obtained by other methods, such as adding or retracting the second lens, changing the curvature of the lens, or moving the light projecting element. It will be done.

〔Effect of the invention〕

As explained above, according to the present invention, the projection angle of the beam bundle is adjusted by the projection angle conversion means, so only one expensive light projection element and one light receiving element are required, and the overall device cost is reduced. It is possible to reduce the Furthermore, since only one light emitting element and one light receiving element are required, the mounting accuracy is not so strict as compared to the conventional art, the structure for mounting is simpler, and the adjustment after mounting is also easier. Furthermore, since it is only necessary to project light once from one light projecting element, distance measurement time can be shortened compared to the conventional method.

In addition, since the specific signal output means outputs the first specific signal or the second specific signal to move the photographing lens to the in-focus position, the photographic screen does not become out of focus and remains within an allowable range.

[Brief explanation of drawings]

11th! FIGS. 1 to 6 show the first distance measuring device according to the present invention.
1 is a schematic overall view of this device, FIG. 2 is a perspective view of a projection angle conversion means, FIG. 3 is a block diagram of a control circuit installed in this device, and FIG. 4 is a flowchart showing the operating procedure of this device, FIGS. 5 and 6 are diagrams showing the operation of this device, and 71! I and the 81st! 7(a) and 7(b) are respectively a plan view and a side view of a light emitting element of this device, and FIG. FIG. 3 is a diagram showing the operation of the device. FIGS. 9 and 10 are schematic overall views showing conventional distance measuring devices, respectively. I... Light projecting element 3... Light projecting lens 4... Light receiving element 5... Light receiving lens 17... Light projecting angle conversion means 18...Specific signal output means or higher

Claims (2)

[Claims] (1) A light projecting element that projects light onto a subject; a light projecting lens that collects the light projected from the light projecting element into a bundle of rays;
and a light-receiving element that is disposed apart from the light-emitting element by a baseline length and receives reflected light from the object through a light-receiving lens, and calculates the distance to the object based on the output of the light-receiving element. In the distance measuring device, the output of the light receiving element cannot be obtained for a narrow light projection angle of the light projection angle converting means;
A distance measuring device comprising specific signal output means for outputting a first specific signal when obtained over a wide projection angle. (2) Specific signal output means that outputs a second specific signal when the output of the light receiving element cannot be obtained for any of the projection angles of the projection angle conversion means. The distance measuring device according to claim 1.