JPH0973119A - Strobe device - Google Patents

Abstract

(57) Abstract: The present invention provides a strobe device in which light distribution does not change depending on distance. According to the present invention, a cross-sectional shape of at least a lateral surface is (x / a) ² − (y / b) ² = with the subject direction being the x axis.
1, a reflecting umbrella formed to form a hyperbola represented by z = c, an arc tube disposed in the vicinity of the front focal point of the reflecting umbrella hyperbola, and the shape of the central portion in the vertical direction forms a convex lens to emit light. The strobe device is composed of a diffuser plate formed so that an optical path of the light directly incident on the lens surface from the tube and refracted and emitted forward is equivalent to a light beam emitted from the hyperbolic rear focus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strobe device for a camera, and more particularly, to improve the shape and arrangement of a stroboscopic arc tube, a reflector and a diffuser plate so that the distribution of radiant flashes is uniform regardless of the distance. Flash device.

[0002]

2. Description of the Related Art As a conventional technique of this kind, in addition to a technique in which a flash of light emitted from an arc tube is reflected by a prism on a side surface and emitted forward in a parallel state, various shapes of a reflecting umbrella and a diffusing plate are devised. Various techniques have been proposed for making the irradiation light of the strobe uniform and making it easy to control.

[0003]

However, in the prior art, the device is complicated, and the light beam directly emitted from the arc tube and the light beam reflected and emitted by the reflecting umbrella intersect each other. However, there is a problem in that the irradiation light distribution of strobe light changes due to an increase in cost and size, or a difference in subject distance, making it difficult to perform various controls such as sensor area setting, light distribution control, and dimming control.

[0004]

SUMMARY OF THE INVENTION The present invention aims to solve these problems of the prior art, and in at least a strobe device including a stroboscopic arc tube, a reflector and a diffuser, the reflector is: The cross-sectional shape of the lateral surface is (x / a) ² − (y / b) ² = 1 and z with the subject direction as the x-axis.
= C, the arc tube is arranged in the vicinity of the front focus on the object side of the reflector hyperbola, and the diffuser plate has a shape of a central portion in the vertical direction as a convex lens. Then, the optical path of the light directly entering the lens from the arc tube and refracting and being emitted forward is formed so as to be equivalent to the virtual ray emitted from the other rear focus of the hyperbolic type, and the arc tube and the reflector The relationship between the diffuser and the diffuser plate is such that the light rays reflected from the arc tube at the curved portion of the rear reflecting umbrella hyperbola and radiated forward through the lens are equivalent to the virtual light rays and directly enter the lens. Light and light other than the two sets of light that is reflected by the curved portion of the reflector and is incident on the lens surface is reflected at a portion in front of the curved portion of the reflector and is condensed on the outside of the lens portion of the diffuser plate. Passes through the part without the light scattering effect and is almost parallel to the two sets of light It is formed so as to elevation to provide a strobe apparatus according to claim.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1, 3, 5, and 7 are schematic cross-sectional side views of an embodiment of the present invention, and FIG. 2, FIG. 4, FIG.
FIG. 8 is an optical path diagram of those examples. In the figure, the same parts are designated by the same reference numerals, and 1 is the front focus of the reflecting umbrella hyperboloid,
Reference numeral 2 is a rear focus which is another focus. 3 is an arc tube of the strobe device, 4 is a cylindrical mirror portion, 5 is a hyperboloidal mirror portion, and the reflecting umbrella is composed of 4 and 5. Reference numeral 6 denotes a diffusion plate, which is composed of a lens portion and an outer portion having no light condensing / scattering effect. Since the cross section of the hyperboloid is a hyperbola, the hyperbolic mirror section is equivalent in structure and operation to the hyperbolic mirror section, and the same applies to the cylindrical mirror section.

Next, the operation in such a configuration will be described. 1, 3, 5, and 7, with the subject direction as the x-axis, (x / a) ² − (y / b) ² = 1 and z =
A ray emitted from the arc tube 3 placed near the focal point 1 (front focal point) of the hyperbolic object side hyperbola represented by c,
The light directly emitted from the arc tube 3 toward the subject is refracted by a lens formed on the diffusion plate 6 and is equivalent to a virtual light ray emitted from the other hyperbolic focus 2 (rear focus). It becomes an optical path. Further, the light having the same angle as the direct ray emission angle and emitted in the opposite direction with the front focal point 1 as the symmetry point is reflected by the concave cylindrical mirror portion 4 whose center angle with the front focal point position 1 as the center is the same as the angle. However, since the light is emitted through the same path as the light directly emitted from the arc tube 3 toward the subject, these light and the light are also emitted from the rear focus 2.

Light rays emitted in a direction other than the above two sets of light, that is, light emitted in a direction which is not directly emitted toward the subject and is not reflected by the concave cylindrical mirror portion, is a hyperbolic mirror. The light is reflected by the part 5 and looks like a light beam from the rear focal point 2. Further, in order not to condense or scatter light on the portion of the diffuser plate through which this light ray passes, a diffuser plate is not arranged, a flat plate is used, By making the shape of an arc centered on the rear focal point 2, the angle of the light beam is maintained so that it looks like the light emitted from the rear focal point 2.

Therefore, the light beam emitted from the arc tube 3 is equivalent to the light beam emitted from the rear focal point 2 in all directions.
The light rays may overlap with each other, but they may not intersect with each other, or even if they do, the light distribution balance becomes very small, and the light distribution balance does not change depending on the distance.

[0009]

Embodiments Although not shown in the embodiment by improving the structure of the present invention, the concave cylindrical surface mirror portion 4 and the hyperboloidal mirror portion 5 may be arranged separately. Although the arc tube and the reflector are in contact with each other, they may be arranged with a space. Furthermore, the present invention is a strobe device in which the diffuser plate portion through which the light rays reflected and emitted by the hyperboloidal mirror pass is a flat plate, and the diffuser plate portion through which the light rays reflected and emitted by the hyperboloidal mirror portion pass. If the intensity of the light reflected by the hyperbolic mirror and emitted from other light sources is not uniform, the strobe device is made cylindrical with the rear focus position as the center, and the reflectance of the reflector or the transmission of the diffuser plate A strobe device that reduces the rate of irradiation so that the light is emitted uniformly, and in the lens that is formed on the diffuser plate so that the light is directly refracted and is emitted from the rear focus, the formation of the diffuser plate Strobe device on the arc tube side,
In the lens that is formed on the diffuser plate by refracting the emitted light directly, so that it becomes the emitted light from the rear focus, the strobe device whose formation is on the subject side of the diffuser plate, refracts the emitted light directly, A strobe device having a Fresnel lens whose shape is a lens formed on the diffusion plate so that the light is emitted from the rear focal point.

[0010]

According to the structure of the present invention, the flash light rays of the strobe device are very small even if they do not intersect, and the light distribution balance does not change even if the distance to the subject changes. The harmful effect of changing the balance depending on the distance is eliminated, and the judgment and control such as changing the sensor area or changing the dimming level in order to prevent the adverse effect are also unnecessary. Further, even if the light distribution is changed depending on the environment, the situation such as the distance, the subject, the brightness of the environment, etc., since the light rays do not intersect, the light distribution change can be controlled relatively easily by the lens, the mirror, the filter, etc. .

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an optical path according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing the configuration of a second embodiment of the present invention.

FIG. 4 is a schematic diagram of an optical path according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram showing the configuration of a third embodiment of the present invention.

FIG. 6 is a schematic diagram of an optical path according to a third embodiment of the present invention.

FIG. 7 is a schematic diagram showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 8 is a schematic diagram of an optical path according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 Front Focus 2 Back Focus 3 Arc Tube 4 Cylindrical Mirror 5 Hyperboloid Mirror 6 Diffuser

Claims (1)

[Claims] 1. A strobe device comprising at least a stroboscopic arc tube, a reflector and a diffusing plate, wherein the reflector has a cross-sectional shape of a lateral side with an object direction being x-axis (x /
a) ²⁻ (y / b) ² = 1 and z = c is formed so as to form a hyperbola, and the arc tube is arranged in the vicinity of the front focus on the object side of the reflector hyperbola, The diffuser plate has a shape of a central portion in the vertical direction as a convex lens, and an optical path that is directly incident on the lens from the arc tube and refracted to be emitted forward is equivalent to a virtual ray emitted from the other rear focal point of the hyperbolic equation. The relationship between the arc tube, the reflector and the diffusing plate is such that the light ray reflected from the arc tube at the curved portion of the rear reflector hyperbola and radiated forward through the lens is the virtual ray. Lights other than the two sets of light that are formed to be equivalent and that are directly incident on the lens and the two sets of light that are reflected by the curved portion of the reflector and are incident on the lens surface are in front of the curved portion of the reflector. A portion outside the lens portion of the diffuser plate that reflects light and has no light condensing / scattering effect Strobe apparatus characterized by being formed so as to as radiation the two pairs of the substantially parallel light.