JPH0854668A - Auxiliary lighting device - Google Patents

Abstract

PURPOSE:To attain a small-sized and suitable lighting even when an auxiliary lighting device is shared with the lighting for mitigating a red-eye at a flash photographing time. CONSTITUTION:A light source 1 is arranged at a position of one side focal point 2a of a reflection shade 2 of which section has an elliptic shape, and the light source 1 is arranged so as to be placed in the vicinity of the focal point of a floodlight lens 3 provided in front of it, and a light beam L1 directly passing through the floodlight lens 3 from the light source 1 is flooded to an object side as a beam of light to be made an auxiliary beam for focal point detection, and the light beam L2 reflected by the reflection shade 2 from the light source 1 and flooded to the object side by the floodlight lens 3 passing through the other focal point 2b is made a diffused light beam to become an auxiliary beam for mitigating the red-eye.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash device used in a photographing device such as a camera, or a camera having the flash device, and an auxiliary device for preventing or mitigating a so-called red-eye phenomenon which occurs when photographing with the flash device. The present invention relates to a lighting device.

[0002]

2. Description of the Related Art In a photographing device such as a camera, an illuminating device which emits a flash light such as a flash device is widely used when the subject brightness is low. When a device that illuminates a subject is used for such an instant shooting, a so-called red-eye phenomenon may occur in which the eyes of humans or animals are shot red.
This red-eye phenomenon occurs when the retina is illuminated by a strong flash of light through a wide-open pupil in a dark environment, and reflected light containing a large amount of the red wavelength is photographed. Therefore, the direction in which the light from the flash device enters the eye tends to become stronger as the shooting optical axis becomes closer to parallel. Especially, in the case of a camera with a built-in electronic flash device, the distance from the shooting optical axis to the flash unit can be set very large. Since it is not present, the red-eye effect is likely to occur.

In order to prevent or mitigate the red-eye phenomenon, a means for performing preliminary illumination prior to the flash illumination at the time of photographing is considered based on the idea that a wide open pupil should be narrowed just before photographing. ing. As a first method, a lamp for performing preliminary light emission is separately provided on a part of a camera or a flash unit, and a subject is illuminated for a certain period of time before photographing. On the other hand, as a second method, there is also known a method in which a flash unit performs preliminary light emission in a pulse form several times prior to main light emission at the time of photographing. Furthermore, as a third method, there is known a method in which a lamp for performing preliminary light emission is provided inside the flashlight reflector.

[0004]

The means for alleviating the red-eye phenomenon in the above-mentioned conventional example has its own features and problems. That is, in the first method, a large lamp and a large amount of electric power for causing the lamp to emit light are required to achieve a sufficient effect, and it is extremely difficult to incorporate the lamp into a camera. Then, in the second method,
A separate lighting device for preliminary light emission is not required, which is very advantageous in terms of space, but an electric control circuit and a capacitor for performing preliminary light emission are required, and depending on the control method, preliminary light emission is also possible. Therefore, there is a concern that the amount of light at the time of main light emission may decrease.

Further, according to the third method, since the reflector and the Fresnel lens of the electronic flash can be used as they are to project light onto the subject, the light of the lamp can be emitted without providing a special optical system. Although it is possible to point the subject to the subject to some extent efficiently, this method is effective so that the effect of inserting the lamp for preliminary light emission inside the reflector of the electronic flash can be almost ignored. It is limited to the case where the or Fresnel lens is sufficiently large, and like the first method, it is difficult to incorporate it into a normal camera.

Therefore, in recent years, there has been known an autofocus camera which receives the brightness distribution information of a subject by a photoelectric element or the like and automatically adjusts the focus of a photographing lens based on the brightness distribution information. It was noted that when a sufficient amount of light for focus detection is not obtained, a part of the subject is illuminated to provide an auxiliary light projecting device for obtaining a sufficient amount of light for focus detection.

In view of the above-mentioned problems of the conventional example, the present invention provides a small auxiliary light illuminating device using the auxiliary light illuminating device of the automatic focus detection device, which is capable of performing appropriate red-eye reduction illumination during flash light photography. To aim.

[0008]

In order to achieve the above-mentioned object, the auxiliary illumination device of the present invention is an auxiliary illumination device for automatic focus detection, which is an illumination device for preliminary illumination of an object prior to flash illumination. A light-emitting portion, a reflecting member having a quadric surface for reflecting light from the light-emitting portion, a direct light from the light-emitting portion, and reflected light from the reflecting member, which are used for an object. If the focal length of the light projecting lens is f and the distance between the center of the light emitting unit and the principal point position of the light projecting lens is d, then 0.5f <
This satisfies the conditional expression of d <1.5f.

A member having a light-shielding portion composed of a fine pattern may be arranged near the focal point of the light projecting lens. Further, it is preferable that the light projecting lens has at least one aspherical surface portion. Further, the light emitted from the light emitting portion and reflected by the reflecting member may be once condensed by the light projecting lens in front of the light projecting lens (on the side of the subject).

[0010]

In the auxiliary illuminating device having the above structure, the beam-like light beam directly passing from the light emitting portion through the light projecting lens becomes the auxiliary illuminating light for automatic focus detection, and the light beam reflected by the reflecting member becomes the diffused light to illuminate the subject. Since the illumination is performed, it is possible to appropriately illuminate the subject in order to alleviate the red-eye phenomenon during flash photography. Further, by providing a member having a light-shielding portion formed of a fine pattern in the vicinity of the focal point of the light projecting lens, the pattern is imaged on the subject side by the light projecting lens, which is effective auxiliary light for focus detection. Further, the light from the light emitting portion reflected by the reflecting member is once condensed on the subject side by the light projecting lens, so that vignetting of the red-eye mitigating light flux due to a light shield such as a photographing lens is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a schematic configuration diagram of this embodiment. In the figure, reference numeral 1 is a light source, and the center thereof coincides with one focus 2a of a reflector 2 formed of the surface of a rotating body having an elliptical cross section. Reference numeral 3 is a projection lens. The center of the light source 1 is arranged near the focus of the light projecting lens 3. Note that L
Reference numeral 1 denotes a light ray which is emitted from the center of the light source 1 and is directly incident on the light projecting lens 3, and L2 is emitted from the center of the light source 1, is reflected by the reflection shade 2, passes through the other focal point 2b of the reflection shade 2, and is projected. It is a light beam projected to the subject side by the light lens 3.

By the way, since the light beam L1 is projected in the form of a beam toward the subject side, sufficient illuminance for focus detection can be obtained. Then, depending on the focus detection range used, the light source 1
The relationship between the center of and the focal position of the projection lens 3 is 0.5f <
Focus detection by a desired beam diameter is satisfied by satisfying d <1.5f (where f is the focal length of the projection lens 3 and d is the distance between the center of the light source 1 and the principal point position of the projection lens 3). Can be an auxiliary light. When the value goes below the lower limit of this conditional expression, the light converging power of the lens 3 does not decrease and the light beam spreads too much, so that the unnecessary light beam increases and the illuminance decreases. On the other hand, when the value exceeds the upper limit, the amount of light flux taken from the light source 1 is small, and the light flux is too wide because it is imaged immediately before the lens, which causes a decrease in illuminance.

On the other hand, the light ray L2 from the reflecting shade 2 is reflected by the reflecting shade 2.
After being focused on one focus 2b of the ellipse having the sectional shape of, the light enters the light projecting lens 3. Then, since the distance between the focal point 2b and the light projecting lens 3 is shorter than the focal length of the light projecting lens 3, the reflected light ray L2 becomes a diffused light, is irradiated to a wide range, and becomes a light beam effective for red eye relief. At this time, the angle θ formed by the straight line x parallel to the optical axis of the light ray L2 is the irradiation angle, which is expressed by the following formula. tan θ = (R / 2) / B where R is the effective diameter of the projection lens 3 and B is the distance between the virtual image position of the focal point 2b of the reflection shade 2 by the projection lens 3 and the principal point position of the projection lens 3. . The relationship between R and B preferably satisfies the following formula. 0.5 ≦ B / R ≦ 0.9 This can be easily achieved by appropriately determining the elliptical cross section of the reflector 2.

2 and 3 show a second embodiment of the present invention. FIG. 2 is a schematic configuration diagram of this embodiment. In the figure, reference numeral 11 denotes a light source, and one of the focal points 12a of a reflector 12 formed by the surface of a rotating body whose center has an elliptical cross section.
Is consistent with Reference numeral 13 is a light projecting lens. Reference numeral 14 denotes a member having a light-shielding portion formed of a fine pattern, which is arranged at the focal position of the light projecting lens 13, and is formed of a thin film shape, and the fine pattern has a shape as shown in FIG.

Incidentally, L11 is a light beam which is emitted from the center of the light source 11, passes through the fine pattern of the member 14 and is directly incident on the light projecting lens 13, and L12 is emitted from the center of the light source 11 and reflected by the reflection shade 12. , L 13 is a light beam that passes through the other focal point 12 b of the reflection shade 12 and is projected to the subject side by the light projecting lens 13, and L 13 is a light beam projected by the light projecting lens 13 from the fine pattern of the member 14.

In this embodiment having the above structure, the member 14
The fine pattern is illuminated by direct light from the light source 11 or reflected light by the reflection shade 12, and is illuminated by projecting and forming the pattern on the subject side by the light projecting lens 13. It is an effective auxiliary light means of the focus detection system for detection.

On the other hand, the light beam L12 from the reflecting shade 12 is focused on one focus 12b of the ellipse, which is the cross-sectional shape of the reflecting shade 12, and then enters the light projecting lens 13. Then, as in the first embodiment, the distance between the focal point 12b and the light projecting lens 13 is shorter than the focal length of the light projecting lens 13, so that the reflected light ray L12 becomes diffused light and is irradiated in a wide range to reduce red eye. It becomes an effective luminous flux. At this time, the angle formed by the straight line x parallel to the optical axis of the light ray L12 is θ, the effective diameter R of the projection lens 13, the virtual image position of the focal point 12b of the reflection shade 12 by the projection lens 13 and the principal point of the projection lens 13. If the distance between the positions is B, it is assumed that the same conditional expression as in the first embodiment is satisfied.

The member 14 having a fine pattern is not limited to the film-like member as in this embodiment, and may be a thin wire or the like which is easy to manufacture. Further, the light projecting lens 13 preferably has a convex aspherical surface on the subject side. In this way, the aspherical surface is formed by the member 1
This is for improving the imaging performance when the pattern chart is inserted in 4.

4 and 5 show a third embodiment of the present invention. FIG. 4 is a schematic configuration diagram of this embodiment. In the figure, reference numeral 21 denotes a light source, the center of which is substantially coincident with a focal point 22a of a reflector 22 made of the surface of a rotating body having a parabolic cross section. A light projecting lens 23 is arranged so that the light source 21 is located near the focus thereof.

L21 is a light beam emitted from the center of the light source 21 and directly incident on the light projecting lens 23, and L22 is emitted from the center of the light source 21 and reflected by the reflection shade 22 to the subject side by the light projecting lens 23. It is the light beam that is projected.

In this embodiment having the above construction, the light ray L2
Since 1 is projected in a beam shape to the subject side, sufficient illuminance for focus detection can be obtained. Then, by appropriately setting the relationship between the center of the light source 21 and the focal position of the light projecting lens 23 according to the focus detection range to be used, it is possible to obtain focus detection auxiliary light with a desired beam diameter.

On the other hand, the light ray L22 reflected by the reflection shade 22 is condensed at a point 24 on the front subject side of the light projecting lens 23, and then diffused at an angle θ as a light flux for red eye relief. Then, once the light is focused on the front side of the light projecting lens 23, it is possible to reduce vignetting due to a light blocking object such as a taking lens.

Vignetting by the lens barrel in this case is shown in FIG.
It will be explained by. In the figure, the light ray L22 is also transmitted together with the light ray L22.
Reference numeral 4 is also a light ray indicating a light beam that diffuses at the same angle θ with respect to the optical axis x of the light projecting device, but is a light ray of the illumination system that spreads without forming an image. Then, the light ray L22 is emitted by the light projecting lens 23.
Since the light is condensed once at the front point 24 of the, the light is projected to the subject side without vignetting by the taking lens 25, but the light ray L24 projected at the same angle θ is blocked by the taking lens 25 and is directed toward the subject. It cannot be projected. In this way, the light flux to be diffused to the front side of the light projecting lens 23 is once condensed at one point, so that the photographing lens 25
Even if there is something that blocks the diffused light flux as described above, it is possible to realize a projection system with little vignetting.

[0024]

Correspondence between the Invention and the Embodiments In the above embodiments, the light sources 1, 11 and 21 correspond to the light emitting portion of the present invention, and the reflection shades 2 and 12 made of the surface of the rotating body having an elliptical cross section and the cross section are formed. Reflective shade 22 composed of the surface of a rotating body having a parabolic shape
Corresponds to a reflecting member having a quadric surface in cross section according to the present invention. Although the above is the correspondence relationship between each configuration of the embodiments and each configuration of the present invention, the present invention is not limited to the configurations of these embodiments, and the functions shown in the claims or the configurations of the embodiments are not limited thereto. It goes without saying that any structure may be used as long as it can achieve the functions it has.

[0025]

As described above, according to the present invention, the auxiliary light illuminating device for automatic focus detection has a light emitting portion and a reflecting member having a quadric surface for reflecting light from the light emitting portion.
A light projecting lens that receives the direct light from the light emitting unit and the reflected light from the reflecting member and projects the light onto an object. The focal length of the light projecting lens is f, and the center of the light emitting unit and the main part of the light projecting lens. If the distance to the point position is d, then 0.5f <d <1.
By constructing to satisfy the conditional expression of 5f,
It is possible to make the auxiliary lighting device that also serves as the red-eye reduction lighting the automatic focus detection lighting device small and good.

Further, by providing a member having a light-shielding portion composed of a fine pattern near the focal point of the light projecting lens,
Auxiliary light effective for focus detection can be obtained, and when a member having such a light shielding portion is used, by forming at least one surface of the light projecting lens into an aspherical surface portion, the imaging performance can be improved. it can. Further, the light from the light emitting portion reflected by the reflecting member is once condensed by the light projecting lens in front of the light projecting lens,
It is possible to reduce the vignetting of the light flux for red-eye reduction due to a light-shielding object such as a photographing lens.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an auxiliary lighting device according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an auxiliary lighting device according to a second embodiment of the present invention.

FIG. 3 is a pattern shape diagram of a member having a light shielding portion formed of the fine pattern.

FIG. 4 is a schematic configuration diagram of an auxiliary lighting device according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of vignetting reduction by the lens barrel.

[Explanation of symbols]

1, 11 21, 21 .. Light source (light emitting part), 2, 12 .. Reflective shade with elliptical cross section 2a, 2b, 12a, 12b .. Focus of elliptical surface, 22 .. Reflective shade with parabolic cross section, 22a
..Focus of parabolic surface, 3,13,23 ..
L1, L2, L11, L12, L13, L21, L22
..Rays

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area G03B 15/02 KS

Claims (4)

[Claims] 1. An auxiliary illuminating device for automatic focus detection, which also serves as an illuminating device for preliminary illumination of an object prior to flash illumination, comprises a light emitting section and a cross section having a quadric surface for reflecting light from the light emitting section. And a light projecting lens that receives the direct light from the light emitting unit and the light reflected by the light reflecting unit and projects the light onto a subject. The focal length of the light projecting lens is f, and the center of the light emitting unit. And a distance from the projection lens to the principal point position is d, the auxiliary lighting device is characterized by satisfying a conditional expression of 0.5f <d <1.5f. 2. The auxiliary lighting device according to claim 1, wherein a member having a light-shielding portion formed of a fine pattern is arranged in the vicinity of the focal point of the light projecting lens. 3. The auxiliary lighting device according to claim 1, wherein the projection lens has at least one aspherical surface portion. 4. The auxiliary illumination according to claim 1, wherein the light from the light emitting portion reflected by the reflecting member is once condensed by the light projecting lens in front of the light projecting lens (on the object side). apparatus.