JPH06331937A - Stereoscopic optical device - Google Patents

Abstract

PURPOSE:To cancel the decrease of an object region and geometric distortion by means of a simple mechanism and to obtain excellent stereoscopic effect for a small object. CONSTITUTION:This device is provided with a right-hand lens 12 and a left-hand lens 13 together composing a stereoscopic lens and a positive-negative combined lens system 14 arranging a negative lens 15 on the object side and a positive lens 16 on the image side and combined with each other and composed so that the principal light rays of the right and the left lenses 12, 13 travel toward the center of an object at a near distance by means of the positive-negative combined lens system 14 Focusing is preferably performed by moving the negative lens 15. Thus, since the image of the object 3 is formed on the central parts of CCDs 17, 18, the decrease of the superposed portion of the subject and the geometric distortion are canceled. At the same time, the interval between the principal light rays 203, 204 of the left and right lenses 12, 13 becomes smaller from (b) to (a) and the viewing angle 2theta of the principal rays is made small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a stereo optical device for stereoscopically viewing a subject, which is an optical device for photographing or observing applied to an endoscope or the like.

[0002]

2. Description of the Related Art A stereo optical device for photographing and observing a subject as a stereoscopic image is well known. In this stereo optical device, as shown in FIG. 4, right lenses (lens systems) arranged in parallel are arranged. A subject 3 can be focused by 1 and the left lens 2. According to this, the subject 3 is captured by the left and right lenses 1 and 2 at different angles, and the images of the subject 3 viewed from different angles are formed on the imaging planes 4 and 5, respectively. Therefore, if the images obtained by the left and right lenses 1 and 2 are overlapped by the left and right eyes, the subject 3 can be observed as a stereoscopic image.

[0003]

However, in the conventional stereo optical device, as described above, the left and right lenses 1 and 2 are used.
When the objects 3 to be photographed are arranged in parallel, and the object 3 to be photographed is at a short distance, the object image 6 approaches the outer end as shown in FIG. That is, since the right lens 1 and the left lens 2 are arranged at a predetermined interval, the subject image 6 shifts to the right side of the right lens 1 and to the left side of the left lens 2, and a range 100 where the left and right images overlap each other.
Becomes smaller. Therefore, the subject area that can be stereoscopically viewed is narrowed, and a good stereoscopic image cannot be obtained. Further, since the light rays from the subject 3 obliquely enter the right lens 1 and the left lens 2, as shown in the subject image 6 in FIG. 4, the geometrical shape such that the circular subject 3 becomes elliptical. There is a problem that various distortions occur.

Therefore, conventionally, as shown in FIG.
A cylindrical lens La and a fixed lens Lb which can be swung in the left and right direction are provided in front of the left and right lenses 7 and 8 which are provided at the left and right positions and can be moved back and forth for focusing, and act as a declination prism. The one in which the declination lens systems 9 and 10 are arranged is used. A mirror, a wedge prism, or the like can be used instead of the declination lens systems 9 and 10. According to this, the deviation angle lens systems 9 and 1
When the respective cylindrical lenses La of 0 are swung outward according to the distance, the chief rays of the left and right lenses 7 and 8 are directed to the center of the subject 3, which reduces the subject area and reduces the geometrical area. Distortion is eliminated. However, in this case, the mechanism for driving the left and right lenses 7 and 8 of the two systems for focusing as described above and the mechanism for driving the cylindrical lens La in the declination lens systems 9 and 10 according to the distance. There is a problem that two mechanisms are required, the configuration becomes complicated, and at the same time, the device becomes large.

Further, when observing a small subject 3, the present applicant has proposed to stereoscopically observe a site inside the body cavity with an endoscope. In this case, the left and right lenses 7 in FIG. However, there is a problem that the arrangement interval of 8 cannot be made sufficiently small according to the size of the subject 3 due to structural and mounting limitations. That is, although the subject observed by the endoscope has a size of several mm to 10 mm, as shown in FIG. Angle θ crossing at 3
Since 1 becomes large, the stereoscopic effect is unnecessarily exaggerated, and a good stereoscopic image cannot be obtained. Therefore, when stereoscopically viewing the small subject 3, it is necessary for the left and right lenses 7 and 8 to look into the subject 3 at a small angle θ1 corresponding to the small subject.

Further, in the endoscope, the deviation angle lens system 9, 1 is used.
0 will be arranged in a fixed state (the cylindrical lens La will not move), but since it is observed closer than usual, the above-mentioned overlapping ratio of the left and right images is extremely small in comparison with the normal subject 3. Since the geometric distortion becomes large at the same time as it becomes small, there is a problem that it is not easy to remove them.

The present invention has been made in view of the above problems, and an object thereof is to reduce a subject area with a simple mechanism and eliminate geometrical distortion, and at the same time, obtain a good stereoscopic effect for a small subject. The present invention provides a stereo optical device.

[0008]

In order to achieve the above object, a stereo optical device according to a first aspect of the present invention comprises a left and right lens forming a stereo lens, a positive lens on the image side and a negative lens on the object side. And a positive / negative combination lens system configured such that the chief rays of the left and right lenses are directed toward the center of an object at a finite distance. A second aspect of the present invention is characterized in that the positive / negative combination lens system is configured to be capable of focusing by moving either one of the positive lens and the negative lens.

[0009]

According to the above construction, the chief ray of each of the left and right lenses is directed to the center of the subject at a finite distance by the combined function of the positive lens and the negative lens, and the subject image at the center of the field of view is the left and right lenses. Guided to the center of the image plane. Further, at this time, the principal ray traveling toward the subject side is refracted toward the center by the positive lens and is directed from the negative lens toward the subject center, so that the horizontal width of the principal ray of the left and right lenses is narrowed. Therefore, it is possible to capture the subject at a small angle according to the small subject.

Further, if any of the above-mentioned positive and negative lenses is moved back and forth, a focusing action to an arbitrary distance becomes possible, and in this case, a declination angle for chief ray matching, which was conventionally performed by two mechanisms. The function and the focusing function can be realized by one mechanism.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration of a stereo optical device for an electronic endoscope according to an embodiment. FIG. 1 (A) shows a state in which an object at infinity is focused, and FIG. (B) shows a state in which a subject at a short distance (finite distance) is focused. In the figure, a right lens 12 and a left lens 13, which are a set of imaging lenses for forming a stereo lens, are provided in a fixed state with a space b, and a positive / negative combination lens system 14 is provided in front of the left and right lenses 12 and 13. It is attached. The positive / negative combination lens system 14 is configured to include at least a negative lens 15 formed of a concave lens arranged on the object (object) side and a positive lens 16 formed of a convex lens arranged on the image side, and the negative lens of the embodiment. The positive lens 16 and the positive lens 16 are fixed in a state of being adjusted to a predetermined focusing distance. However, when the size of the positive / negative combination lens system 14 is not limited, either the negative lens 15 or the positive lens 16 can be configured to be movable so that focusing can be performed at an arbitrary distance. preferable.

Further, in this positive / negative combination lens system 14,
When the subject is at infinity, as shown in FIG. 1A, when the principal rays 201 and 202 of the right lens 12 and the left lens 13 are considered in the opposite direction to the actual light traveling, a positive lens 16 and the negative lens 15 are arranged so as to be parallel rays. On the other hand, when the subject is at a finite distance, as shown in FIG. 1B, the negative lens 15 is extended by the length L from the state of FIG. The chief rays 203 and 204 are arranged so as to pass through the positive lens 16 and the negative lens 15 and cross at the center of the subject 3 at a predetermined distance (range).

According to the positive / negative combination lens system 14, as shown in both FIGS. 1 (A) and 1 (B), the principal rays 201 and 202 and 203 and 204 are
The positive lens 16 refracts toward the center side, and the negative lens 15 moves toward the subject 3 without spreading.
The chief rays 201, 202 or 20 at positions 2, 13
The distance b of 3,204 is small on the object side a (a <a <
narrowed down to b). Further, a CCD (Charge), which is a solid-state image sensor, is provided after the right lens 12 and the left lens 13.
Coupled Device) 17 and 18 are provided, and the subject image captured by the left and right lenses 12 and 13 is the CCD
An image is formed on the imaging planes 17 and 18.

According to the configuration of the above-described embodiment, in the case of an infinite object as described above, focusing can be performed at infinity by the setting of FIG. 1A, and in the case of a short-distance object 3, FIG.
As shown in (B), by focusing the negative lens 15 to a predetermined position, focusing can be performed within a predetermined distance range.
At the same time, the chief rays 203 and 204 of the left and right lenses 12 and 13 looking into the subject 3 can be crossed at the center of the subject 3, and the distance between the chief rays of the left and right lenses 12 and 13 is b.
To a. As a result, as shown in FIG. 2, the angle θ at which the chief rays 203 and 204 at the interval a are expected.
2 is a chief ray 203, 2 with a spacing b (similar to FIG. 5 of the prior art).
The angle is smaller than the expected angle θ1 of 04 (θ2 <θ1).
Therefore, the subject 3 can be captured from the left and right with a small angle, and a good stereo image corresponding to the small subject 3 can be obtained by the CCDs 17 and 18.

Then, as shown in FIG.
In D17, the subject image 20 formed by the right lens 12
However, in the CCD 18, the subject image 20 of the left lens 13 is formed at the center position. Therefore, the left and right lenses 1
The overlapping range of the images obtained in 2 and 13 can be made large, and the geometric distortion of the images can be eliminated.

Further, the negative lens 15 or the positive lens 16 is used.
When either one of the above is configured to be movable back and forth so that focusing can be performed at an arbitrary distance, as described above, one mechanism of the positive / negative combination lens system 14 has the function of focusing and the subject. Two functions of the declination function of crossing the chief rays of the left and right lenses 12 and 13 which see 3 can be executed.

[0017]

As described above, according to the invention of the first aspect, a negative lens is arranged on the object side and a positive lens is arranged on the image side, and the left and right lenses have a chief ray at a finite distance. Since the positive / negative combination lens system configured to face the center of the object is arranged in front of the pair of left and right lenses, a simple mechanism can reduce the subject area and eliminate geometric distortion. Since the distance between the chief rays of the left and right lenses is narrowed, a good stereoscopic effect can be obtained.

Further, according to the second aspect of the invention, since the focusing is possible by the movement of either one of the positive and negative lenses, the declination function for the principal ray matching can be achieved by one mechanism. Both the focusing function and the focusing function can be performed, and a small optical device can be obtained.

[Brief description of drawings]

FIG. 1 is a top view showing a schematic configuration of a stereo optical device according to an embodiment of the invention.

FIG. 2 is an explanatory diagram showing an expected angle of a chief ray.

FIG. 3 is a diagram showing an image formation state in an example.

FIG. 4 is a diagram showing a schematic configuration of a conventional stereo optical device and an image formation state thereof.

FIG. 5 is a top view showing a schematic configuration of a conventional device including a deviation lens system.

[Explanation of symbols]

 1,7,12 ... Right lens, 2,8,13 ... Left lens, 3 ... Subject, 14 ... Positive / negative combination lens system, 15 ... Negative lens, 16 ... Positive lens, 17, 18 ... CCD.

Claims (2)

[Claims] 1. A left and right lens forming a stereo lens, a positive lens on the image side, and a negative lens on the object side are arranged so that the chief rays of the left and right lenses are directed toward the center of an object at a finite distance. A positive / negative combination lens system configured,
Stereo optical device consisting of. 2. The stereo optical device according to claim 1, wherein the positive / negative combination lens system is configured so that focusing can be performed by moving either the positive lens or the negative lens.