JPH09138449A - Irradiating angle variable type illumination optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an irradiating angle variable type illumination optical system which can execute such an efficient illuminating action that the loss of light quantity is reduced extending over a telephoto end from a wide-angle end by providing it with a first reflection means integrally moved with a light emission means and a second reflection means fixed when an irradiating angle is changed. SOLUTION: On the wide-angle end, luminous flux emitted from a xenon tube 1 is directly made incident on a Fresnel lens 2, or it is made incident on the lens 2 after it is reflected on a reflector 3w arranged on the wide-angle end once. On the telephoto end, the luminous flux emitted from the tube 1 is directly made incident on the lens 2, or it is made incident on the lens 2 after it is reflected on a reflector 3t arranged on the telephoto end once, or it is made incident on the lens 2 after it is reflected on a reflection plate 4 once or it is made incident on the lens 2 after it is successively reflected on the reflector 3 and the plate 4. Thus, an object can be efficiently illuminated without losing the light quantity extending over the wide-angle end from the telephoto end by the reflecting action of the plate 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical system having a variable irradiation angle, and more particularly to an illumination optical system having a variable irradiation angle which is suitable for a camera or the like for illuminating a predetermined range. is there.

[0002]

2. Description of the Related Art FIG. 10 is a perspective view of a camera having a conventional illumination optical system. The camera of FIG. 10 has a camera body 1
1 is provided. Front side of the camera body 11 (subject side)
Includes a taking lens 12 having an optical axis 14 as shown in the figure.
A finder window 13, an AF (autofocus) light emitting / receiving window 15, and an illumination optical system 17 are arranged.

A release button 16 is provided on the upper surface side of the camera body 11. In order to mitigate the red-eye phenomenon (a phenomenon in which the eyes appear red), the illumination optical system 17
Are arranged as far away from the taking lens 12 as possible. That is, when the camera body 11 is viewed from the front, the illumination optical system 17 is arranged at the right end corner (or the left end corner) of the camera body 11.

FIG. 11 is an enlarged perspective view of the illumination optical system 17 of FIG. Further, FIG. 12 shows the illumination optical system 1 of FIG.
7 is a cross-sectional view of FIG. 7, taken along a plane perpendicular to the longitudinal axis of the xenon tube 1. Further, FIG.
It is an optical-path figure in the wide-angle end of the illumination optical system of 0. Also,
FIG. 14 is an optical path diagram at the telephoto end of the illumination optical system in FIG. The subscripts w and t in FIGS. 11 to 14 are
The state where the irradiation angle is wide, that is, the wide-angle end, and the state where the irradiation angle is smallest, that is, the telephoto end, are shown.

As shown in FIGS. 10 to 12, the illumination optical system 17 comprises a cylindrical and straight tube type xenon tube 1, a reflector 3 and a Fresnel lens 2. The xenon tube 1, which is a light emitting source, is positioned so that its longitudinal axis is perpendicular to the optical axis 14 of the taking lens 12.
The luminous intensity of the luminous flux emitted from the xenon tube 1 is substantially uniform in the radial direction. Therefore, in order to efficiently direct the light flux emitted from the xenon tube 1 toward the subject, the reflector 3 is arranged on the side opposite to the subject. The reflector 3 has a shape surrounding the xenon tube 1 and reflects the light from the xenon tube 1 toward the Fresnel lens 2.

The optical axis 5 of the Fresnel lens 2 is parallel to the optical axis 14 of the taking lens 12, and the center axis (outer diameter center) of the outer diameter shape (the shape defined by the outer surface) of the Fresnel lens 2 is used. Axis). Further, the surface of the Fresnel lens 2 on the object side (right side in FIG. 12) is formed in a plane shape perpendicular to the optical axis 5 of the Fresnel lens 2. On the other hand, the surface of the Fresnel lens 2 on the xenon tube 1 side is formed in a Fresnel surface shape including a plurality of annular Fresnel elements with the lens optical axis 5 as the center of rotation.

Thus, the luminous flux emitted from the xenon tube 1 is reflected by the reflector 3 and enters the Fresnel lens 2 indirectly or directly from the xenon tube 1. The light refracted by the Fresnel lens 2 is taken by the photographing lens 1.
It is oriented so as to illuminate the two photographing ranges. The irradiation angle of the illumination optical system 17 is changed so that the photographing range of the photographing lens 12 at a predetermined distance is well illuminated when the magnification of the photographing lens 12 is changed.

By the way, in recent years, as a lens shutter type camera, a camera equipped with a high zoom lens is becoming mainstream. In such a high zoom lens, the F number is large at the telephoto end, and a strong illumination optical system is necessary to obtain good exposure characteristics. Then, at the telephoto end, it is necessary to collect the luminous flux in a narrow photographing range, and conversely, at the wide angle end, it is necessary to uniformly illuminate the wide photographing range.

Therefore, as shown in FIGS. 13 and 14, the xenon tube 1 and the reflector 3 are arranged with respect to the Fresnel lens 2 in order to adjust the illumination range to the photographing range which changes as the photographing lens 12 changes in magnification. The lens is moved integrally along the lens optical axis 5 to change the illumination range (that is, the irradiation angle). Note that, in FIGS. 13 and 14, only the rays of light directed upward with respect to the xenon tube 1 are shown, but the rays of light directed downward and the rays of light directed upward are line-symmetric with respect to the lens optical axis 5.

[0010]

As shown in FIGS. 13 and 14, in the conventional illumination optical system with a variable irradiation angle, the distance between the xenon tube 1 and the Fresnel lens 2 increases at the telephoto end rather than the wide-angle end. To do. Therefore, at the telephoto end, as shown in FIG. 14, a part of the light beam emitted from the xenon tube 1 does not go to the Fresnel lens 2 and the inner surface 6 of the lens barrel is
Incident on. Since the inner surface 26 of the lens barrel is black and has a low reflectance, the light flux indicated by the shaded portion in the drawing does not contribute to illumination. That is, at the telephoto end, efficient illumination cannot be performed, and the light flux incident on the inner surface 6 of the lens barrel is absorbed and the temperature of the lens barrel itself rises.

By the way, since making the taking lens long in focus is particularly suitable for taking an image of a distant subject, it is desirable that the illumination optical system can also illuminate a far away subject as the taking lens becomes long in focus. However, in order to illuminate a distant subject, it is necessary to increase the light emission amount of the illumination optical system, and to increase the light emission amount of the illumination optical system, it is necessary to increase the light emission amount of the light emission light source. as a result,
As described above, there is a disadvantage that the amount of light absorbed by the lens barrel increases and the temperature of the lens barrel rises extremely.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide an illumination optical system with a variable irradiation angle capable of performing efficient illumination with a small light amount loss from the wide-angle end to the telephoto end. To aim.

[0013]

In order to solve the above problems, in the present invention, a light emitting means for supplying illumination light and a light beam from the light emitting means are directed toward a predetermined range by refraction. And a reflection means for reflecting the light flux from the light emitting means toward the refraction means, and an irradiation angle for changing the irradiation angle by moving the light emission means with respect to the refraction means. In the variable illumination optical system, the reflecting means has a first reflecting means that moves integrally with the light emitting means when changing the irradiation angle, and a second reflecting means that is fixed when changing the irradiation angle. Then, from the wide-angle end closest to the refracting means by the light emitting means to the telephoto end farthest from the refracting means by the light emitting means, the light directly going to the refracting means out of the luminous flux from the light emitting means. Light flux other than provide illumination angle variation of the illumination optical system characterized in that it is reflected toward the refracting means by at least one of the reflecting means of said first reflecting means and said second reflecting means.

According to a preferred aspect of the present invention, at the wide-angle end, the light flux from the light emitting means other than the light flux directly directed to the refracting means is reflected toward the refracting means by the first reflecting means. Then, as the irradiation angle is changed from the wide-angle end to the telephoto end, the light flux reflected by the second reflecting means toward the refracting means gradually increases.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION First, in an illumination optical system used in a camera or the like, a subject is illuminated while the taking lens is exposed. In particular, when the subject is illuminated in a dark shooting scene or the like, a light source that instantaneously emits a powerful light amount is desirable as the light emitting light source. Therefore, in an illumination optical system used for a camera or the like, a xenon flash lamp is generally used as a light emitting light source. The light emitting portion of the xenon flash lamp has a rod shape and a cylindrical shape as a whole, and is called a xenon tube. The emission intensity distribution is rotationally symmetrical with respect to the longitudinal axis of the xenon tube, and the light intensity distribution is constant along the longitudinal axis of the xenon tube.

A lens component having a refracting action (condensing action) is used as the refracting means for directing the luminous flux emitted from the light emitting light source so as to illuminate a predetermined photographing range. In particular, a plastic material is often used as an optical material so that the lens component can be easily held and can be manufactured at low cost. Further, as a lens component, a Fresnel lens with a small change in thickness between the central portion and the peripheral portion is generally used.

When the illumination optical system according to the present invention is incorporated in a camera, it is desirable that the illumination range of the illumination optical system covers the photographing range of the photographing lens. However, as described above, in order to prevent the red-eye phenomenon, the taking lens and the illumination optical system are arranged separately. Therefore, it is necessary to illuminate the shooting range satisfactorily regardless of the subject position in consideration of the occurrence of parallax depending on the subject position.

FIG. 1 is a perspective view showing the structure of a camera incorporating the illumination optical system according to the present invention. The camera of FIG. 1 includes a camera body 11. On the front side (subject side) of the camera body 11, as shown, a taking lens 12 having an optical axis 14, a finder window 13, an AF light emitting / receiving window 1
5 and the illumination optical system 17 are arranged.
Further, the release button 1 is provided on the upper surface side of the camera body 11.
6 are provided.

FIG. 2 is an enlarged perspective view schematically showing the structure of the illumination optical system shown in FIG. 3 is a cross-sectional view of the illumination optical system of FIG. 1 at the wide-angle end, which is a cross-sectional view taken along a plane perpendicular to the longitudinal axis of the xenon tube 1. 4 is a cross-sectional view of the illumination optical system of FIG. 1 at the telephoto end, taken along a plane perpendicular to the longitudinal axis of the xenon tube 1. The subscripts w and t in FIGS. 2 to 4 indicate the state where the irradiation angle is the widest, that is, the wide-angle end, and the state where the irradiation angle is the smallest, that is, the telephoto end.

As shown in FIGS. 2 to 4, the illumination optical system 17
Is a cylindrical straight tube type xenon tube 1, reflector 3,
It comprises a reflector 4 and a Fresnel lens 2. The longitudinal axis of the xenon tube 1, which is a light emitting source, is the photographing lens 1.
It is positioned so as to be perpendicular to the second optical axis 14. The reflector 3 has a shape that surrounds the xenon tube 1 and reflects the light from the xenon tube 1 into the Fresnel lens 2
Reflect toward. The reflector 4 (shown by a broken line in FIG. 2) extends between the edge of the reflector 3 (see FIG. 4) and the edge of the Fresnel lens 2 at the telephoto end.
Its inner peripheral surface is formed as a reflecting surface.

The optical axis 5 of the Fresnel lens 2 is parallel to the optical axis 14 of the taking lens 12, and the center axis (outer diameter center) of the outer diameter shape (shape defined by the outer surface) of the Fresnel lens 2 is used. Axis). Further, the surface of the Fresnel lens 2 on the object side (right side in FIGS. 3 and 4) is formed in a plane shape perpendicular to the optical axis 5 of the Fresnel lens 2. On the other hand, the xenon tube 1 of the Fresnel lens 2
The surface on the side is formed in a Fresnel surface shape composed of a plurality of annular Fresnel elements with the lens optical axis 5 as the center of rotation.

As described above, the Fresnel lens 2 is arranged on the illumination range side of the xenon tube 1 and constitutes a refraction means for directing the luminous flux emitted from the xenon tube 1 so as to illuminate a predetermined illumination range. In this way, the light flux emitted from the xenon tube 1 is reflected by the reflector 3 and the reflection plate 4 and enters the Fresnel lens 2 indirectly or directly from the xenon tube 1. The light refracted by the Fresnel lens 2 is directed so as to illuminate the photographing range of the photographing lens 12.

Then, by moving the xenon tube 1 and the reflector 3 integrally along the lens optical axis 5, that is, by changing the distance between the xenon tube 1 and the Fresnel lens 2, illumination at a predetermined distance is performed. By changing the range, the irradiation angle is changed.

FIG. 5 is an optical path diagram at the wide-angle end of the illumination optical system of FIG. FIG. 6 is an optical path diagram at the telephoto end of the illumination optical system of FIG. Subscript w in FIGS. 5 and 6
And t indicate the state where the irradiation angle is the widest, that is, the wide angle end, and the state where the irradiation angle is the smallest, that is, the telephoto end. Further, in FIGS. 5 and 6, only the rays of light directed upward with respect to the xenon tube 1 are shown, but the rays of light directed downward and the rays of light directed upward are line-symmetric with respect to the lens optical axis 5.

At the wide-angle end, as shown in FIG. 5, the light beam emitted from the xenon tube 1 is directly incident on the Fresnel lens 2, or is reflected by the reflector 3 and then incident on the Fresnel lens 2. . In this way, the light flux incident on the Fresnel lens 2 is refracted by the Fresnel lens 2 and illuminates the subject.

On the other hand, at the telephoto end, as shown in FIG. 6, the luminous flux emitted from the xenon tube 1 directly goes to the Fresnel lens 2.
, Or the Fresnel lens 2 after being reflected by the reflector 3 or the Fresnel lens 2 after being reflected by the reflector 4 or the reflector 3 and the reflector 4 sequentially. Then, the light enters the Fresnel lens 2. In this way, the light flux incident on the Fresnel lens 2 is refracted by the Fresnel lens 2 and illuminates the subject. That is, due to the reflecting action of the reflecting plate 4, it is possible to efficiently illuminate the subject without loss of light amount from the telephoto end to the wide-angle end.

In the embodiment of the present invention shown in FIGS. 1 to 6, the reflector 4 is shielded by the reflector 3 at the wide-angle end where the irradiation angle is widest, and does not contribute to the reflecting action. However, when changing the irradiation angle from the wide-angle end to the telephoto end with the narrowest irradiation angle, the reflector 3 and the xenon tube 1 move integrally along the lens optical axis 5 with respect to the fixed reflection plate 4. To do. Thus, as the irradiation angle changes from the wide-angle end to the telephoto end, the portion of the reflection plate 4 whose reflection action is blocked by the reflection umbrella 3 decreases, and the portion of the reflection plate 4 that blocks the light flux by the reflection umbrella 3 at the telephoto end disappears. .

However, when actually incorporating the illumination optical system of the present invention into a camera, a portion where the reflector 4 and the reflector 3 overlap is required for the convenience of holding the reflector 4 and the like. Therefore, the reflector 4 is not completely shielded by the reflector 3 at the wide-angle end, and the reflector 4 is not completely shielded by the reflector 3 at the telephoto end.

As shown in FIG. 14, in the conventional illumination optical system with a variable irradiation angle, the light flux emitted from the light source at the telephoto end is arranged along the lens optical axis 5 of the reflector 3 so that the subject is illuminated effectively. It was necessary to secure a large length. Therefore, the Fresnel lens 2 and the xenon tube 1 cannot be brought sufficiently close to each other at the wide-angle end, and a large amount of extra space is required between the Fresnel lens 2 and the xenon tube 1. Further, since the refraction effect of the Fresnel lens 2 is weakened, the moving distance of the xenon tube 1 and the reflector 3 from the wide-angle end to the telephoto end becomes large, resulting in insufficient space saving.

In the present invention, by disposing the reflection plate 4, the illumination efficiency at the telephoto end is enhanced. in addition,
It is possible to shorten the length of the reflector 3 along the lens optical axis 5 by increasing the length of the reflector 4 along the lens optical axis 5. As a result, the Fresnel lens 2 and the xenon tube 1 can be brought sufficiently close to each other at the wide-angle end, and space saving can be achieved at the same time.

Further, as shown in the following embodiments, according to the present invention, the lens optical axis 5 of the Fresnel lens 2 is not necessarily parallel to the optical axis 14 of the taking lens 12. That is, even when the lens optical axis 5 of the Fresnel lens 2 is arranged so as to be inclined with respect to the optical axis 14 of the taking lens 12, the Fresnel lens 2 can correct the deviation of the illumination range and obtain good illumination characteristics.

[0032]

An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 7 is a sectional view showing the optical arrangement of the illumination optical system according to the first example of the present invention, in which (a) is taken along the plane including the longitudinal axis of the xenon tube 1 and the lens optical axis 5. It is a sectional view, (b) is a sectional view taken along a plane perpendicular to the longitudinal axis of the xenon tube 1. In FIG. 7, the subscripts w and t of the xenon tube 1 and the reflector 3 are in a state where the illumination range is widest (that is, the irradiation angle is the widest) at a predetermined distance, that is, at the wide-angle end and the narrowest (that is, the irradiation angle is the narrowest). ) The state, that is, the telephoto end, is shown.

As shown in FIG. 7, in the first embodiment, the optical axis 5 of the Fresnel lens 2 is parallel to the optical axis 14 of the taking lens 12, and the outer diameter shape of the Fresnel lens 2 (depending on the outer surface). It coincides with the center axis (outer diameter center axis) of the prescribed shape). The lens optical axis 5 and the xenon tube 1 are on the same plane, and the xenon tube 1 extends perpendicularly to the lens optical axis 5. Then, when the irradiation angle from the wide-angle end to the telephoto end is changed, the xenon tube 1 moves so as to move away from the Fresnel lens 2 along the lens optical axis 5 in the plane including the longitudinal axis of the xenon tube 1 and the lens optical axis 5. To do.

In the first embodiment, the outer diameter shape of the Fresnel lens 2 is a rectangular shape as shown in FIG. 8 when viewed from the direction of the lens optical axis 5. The surface of the Fresnel lens 2 on the illumination range side is formed in a plane shape perpendicular to the lens optical axis 5, and the surface on the side of the xenon tube 1 is formed in a Fresnel surface shape. Further, as shown in FIG. 7, the reflection plate 4 extends between the edge portion of the reflector 3 and the edge portion of the Fresnel lens 2 at the telephoto end, and the inner peripheral surface thereof is formed as a reflection surface. ing.

Therefore, at the wide-angle end, the light beam emitted from the xenon tube 1 directly enters the Fresnel lens 2 or, after being once reflected by the reflector 3w, enters the Fresnel lens 2. In this way, the light flux incident on the Fresnel lens 2 is refracted by the Fresnel lens 2 and illuminates the subject. On the other hand, at the telephoto end, the light beam emitted from the xenon tube 1 is directly incident on the Fresnel lens 2, or is once reflected by the reflector 3t and then is incident on the Fresnel lens 2 or is once reflected by the reflector 4. After Fresnel lens 2
Or is incident on the Fresnel lens 2 after being sequentially reflected by the reflector 3 and the reflector 4.

Thus, the light beam incident on the Fresnel lens 2 is refracted by the Fresnel lens 2 and illuminates the subject. That is, due to the reflecting action of the reflecting plate 4, it is possible to efficiently illuminate the subject without loss of light amount from the telephoto end to the wide-angle end. As described above, in the first embodiment, good illumination characteristics can be obtained based on the above configuration. Therefore, when applied to the illumination optical system of a camera, the photographing range of the photographing lens can be illuminated well from the wide-angle end to the telephoto end.

FIG. 9 is a sectional view showing the optical arrangement of the illumination optical system according to the second embodiment of the present invention, in which (a) is a plane containing the longitudinal axis of the xenon tube 1 and the reference optical axis 38. FIG. 3B is a cross-sectional view taken along line (b), which is a cross-sectional view taken along a plane perpendicular to the longitudinal axis of the xenon tube 1. In FIG. 9, the subscripts w and t of the xenon tube 1 and the reflector 3 are
The state where the illumination range is wide (that is, the irradiation angle is the widest) at a predetermined distance, that is, the wide-angle end, and the state where the illumination range is the narrowest (that is, the irradiation angle is the narrowest), that is, the telephoto end, are shown.

In FIG. 9, the central axis of the outer diameter shape of the Fresnel lens 2 is indicated by the reference numeral 36. Further, the intersection of the lens optical axis 5 of the Fresnel lens 2 and the Fresnel lens 2, that is, the lens center is indicated by reference numeral 37. The axis 38 indicates a reference optical axis that is parallel to the optical axis 14 of the taking lens 12 and passes through the lens center 37.

As shown in FIG. 9, in the second embodiment, the lens optical axis 5, the outer diameter center axis line 36, the reference optical axis 38, and the xenon tube 1 exist on the same plane. The lens optical axis 5 and the reference optical axis 38 form a predetermined angle in the plane including the longitudinal axis of the xenon tube 1 and the reference optical axis 8. Further, the outer diameter center axis line 36 and the reference optical axis 38 are parallel to each other. Further, the xenon tube 1 extends perpendicularly to the reference optical axis 38, and when the irradiation angle is changed from the wide-angle end to the telephoto end, the reference optical axis is within a plane including the outer diameter center axis 36 and the reference optical axis 38. It moves along the line 38 away from the Fresnel lens 2.

In the second embodiment, the outer diameter shape 4 of the Fresnel lens 2 is as shown in FIG. 8 when viewed from the direction of the lens optical axis 5.
It has a rectangular shape as shown in. And Fresnel lens 2
The surface on the illumination range side is formed in a plane shape perpendicular to the lens optical axis 5, and the surface on the xenon tube 1 side is formed in a Fresnel surface shape. Further, as shown in FIG. 9, the reflection plate 4 extends between the edge portion of the reflector 3 and the edge portion of the Fresnel lens 2 at the telephoto end, and the inner peripheral surface thereof is formed as a reflection surface. ing.

Therefore, at the wide-angle end, the light beam emitted from the xenon tube 1 is directly incident on the Fresnel lens 2 or, after being once reflected by the reflector 3w, is incident on the Fresnel lens 2. In this way, the light flux incident on the Fresnel lens 2 is refracted by the Fresnel lens 2 and illuminates the subject. On the other hand, at the telephoto end, the light beam emitted from the xenon tube 1 is directly incident on the Fresnel lens 2, or is once reflected by the reflector 3t and then is incident on the Fresnel lens 2 or is once reflected by the reflector 4. After Fresnel lens 2
Or is incident on the Fresnel lens 2 after being sequentially reflected by the reflector 3 and the reflector 4.

Thus, the light flux incident on the Fresnel lens 2 is refracted by the Fresnel lens 2 and illuminates the subject. That is, due to the reflecting action of the reflecting plate 4, it is possible to efficiently illuminate the subject without loss of light amount from the telephoto end to the wide-angle end. As described above, also in the second embodiment, good illumination characteristics can be obtained based on the above configuration. Therefore, when applied to the illumination optical system of a camera, the photographing range of the photographing lens can be illuminated well from the wide-angle end to the telephoto end.

In each of the above-mentioned embodiments, an example in which a xenon tube is used as a light emitting light source has been shown, but it is also possible to use another suitable light emitting light source such as a halogen lamp or an LED.

[0044]

As described above, according to the present invention, it is possible to achieve an illumination optical system with a variable irradiation angle that can save space and can perform efficient illumination with a small light amount loss from the wide-angle end to the telephoto end. can do. In addition, as shown in the second embodiment, even if the shape of the front surface of the camera is made to be a design-oriented shape,
The illumination optical system with variable irradiation angle according to the present invention can illuminate a subject satisfactorily from the wide-angle end to the telephoto end.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a camera incorporating an illumination optical system according to the present invention.

FIG. 2 is an enlarged perspective view schematically showing the configuration of the illumination optical system of FIG.

3 is a cross-sectional view of the illumination optical system of FIG. 1 at a wide-angle end, which is a cross-sectional view taken along a plane perpendicular to a longitudinal axis of the xenon tube 1.

4 is a sectional view of the illumination optical system of FIG. 1 at a telephoto end, which is a sectional view taken along a plane perpendicular to a longitudinal axis of the xenon tube 1. FIG.

5 is an optical path diagram at the wide-angle end of the illumination optical system in FIG.

FIG. 6 is an optical path diagram at the telephoto end of the illumination optical system in FIG.

FIG. 7 is a cross-sectional view showing the optical arrangement of the illumination optical system according to the first example of the present invention, in which (a) is taken along the plane including the longitudinal axis of the xenon tube 1 and the lens optical axis 5. It is a sectional view, (b) is a sectional view taken along a plane perpendicular to the longitudinal axis of the xenon tube 1.

8 is a diagram showing the outer diameter shape of the Fresnel lens 2 of FIGS. 7 and 9. FIG.

FIG. 9 is a cross-sectional view showing an optical arrangement of an illumination optical system according to a second example of the present invention, in which (a) is taken along a plane including a longitudinal axis of the xenon tube 1 and a reference optical axis 38. It is a sectional view, (b) is a sectional view taken along a plane perpendicular to the longitudinal axis of the xenon tube 1.

FIG. 10 is a perspective view of a camera including a conventional illumination optical system.

11 is an enlarged perspective view of the illumination optical system 17 of FIG.

12 is a sectional view of the illumination optical system 17 of FIG.
FIG. 3 is a cross-sectional view taken along a plane perpendicular to the longitudinal axis of the xenon tube 1.

13 is an optical path diagram at the wide-angle end of the illumination optical system in FIG.

14 is an optical path diagram at the telephoto end of the illumination optical system in FIG.

[Explanation of symbols]

 1 Xenon tube 2 Fresnel lens 3 Reflector 4 Reflector 5 Optical axis of Fresnel lens 6 Lens barrel surface 11 Camera body 12 Photographing lens 13 Finder window 14 Optical axis of photography lens 15 AF light emitting / receiving window 16 Release button 17 Illumination optical system 36 outer diameter center axis 37 lens center 38 reference optical axis

Claims (4)

[Claims] 1. A light emitting means for supplying illumination light, a refracting means for directing a light beam from the light emitting means toward a predetermined range by refraction, and a light beam from the light emitting means to the refracting means. In the illumination optical system with a variable irradiation angle, the irradiation angle is changed by moving the light emitting means with respect to the refracting means, and the reflecting means changes the irradiation angle. In this case, the light emitting means has a first reflecting means that moves integrally with the light emitting means, and a second reflecting means that is fixed when the irradiation angle is changed, and the light emitting means is located at the wide-angle end closest to the refracting means. Of the light flux from the light emitting means, the light flux other than the light flux directly directed to the refraction means over the telephoto end farthest from the refraction means by the light emission means passes through the first reflection means and the second reflection means. At least one illumination optical system illuminating angle variable, characterized in that it is reflected toward the refracting means by the reflection means. 2. At the wide-angle end, the light flux from the light emitting means other than the light flux directly directed to the refracting means is reflected toward the refracting means by the first reflecting means, and the wide-angle end to the telephoto end. The illumination optical system according to claim 1, wherein the luminous flux reflected by the second reflecting means toward the refracting means gradually increases as the irradiation angle changes. 3. The first reflecting means is a reflector arranged on the side opposite to the refracting means side with respect to the light emitting means, and surrounds the light emitting means, and the second reflecting means. 3. The variable irradiation angle according to claim 1, wherein the means is a reflector extending between the edge of the refracting means and the edge of the reflector at the telephoto end. Illumination optics. 4. The illumination optical system with variable irradiation angle according to claim 1, wherein the light emitting means is a xenon tube.