JP2871133B2 - Strobe device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash device (flash light emitting device) suitable for a photographic camera or video camera for 35 mm film, and more particularly, to a small-sized and high-efficiency light source for effectively utilizing a light beam from a light emitting means. The present invention relates to a strobe device.

[0002]

2. Description of the Related Art Strobe devices (flash light emitting devices) have been frequently used for nighttime shooting, indoor shooting, and backlit shooting. Techniques for improving the use efficiency of the irradiation light beam of these strobe devices are disclosed in, for example, Japanese Patent Publication No. 53-874 and Japanese Utility Model Publication No. Sho 60-177.
No. 410, for example.

[0003] In general, a stroboscopic device is composed of a cylindrical discharge tube as a light emitting portion, a reflecting mirror surrounding the discharge tube except for an irradiation port, and a condenser lens (light projection lens) mounted in front of the irradiation port. ing.

FIG. 7 is a schematic view of a condensing lens using a Fresnel lens on one surface among condensing lenses used in a conventional strobe device. FIG. 7A is a front view, and FIG.
FIG. 7B is an upper sectional view, and FIG. 7C is a side sectional view.
In the figure, 7b is a Fresnel lens surface, and 7a is a plane.

FIG. 8 is an enlarged view of a light beam passing through a part of the Fresnel lens portion 7b of FIG. As is apparent from the drawing, the Fresnel lens is not required for illumination for connecting the lens portions 82 due to its structure when forming a large number of lens groups (deflection portions) 82 each having an inclined surface that performs a light deflecting action. A simple wall portion 81 is formed.

In FIG. 8, a light beam L8 in a hatched portion sandwiched between dotted lines incident on a wall portion 81 is scattered without receiving a desired lens action (deflection action) unlike light incident on a lens section 82. At this time, the light loss of the light beam L8 passing through the shaded portion causes a reduction in the amount of illumination and uneven illuminance.

[0007]

In recent years, miniaturization of cameras has progressed, and zoom lenses have come to be widely used as standard lenses in photographing systems. For this reason, there is a demand for a strobe device for a camera, particularly for a strobe device with a built-in camera, to be reduced in size and to have a zoom that can change the irradiation angle.

In order to effectively reduce the size and zoom of the strobe device, it is necessary to reduce the size of the reflector and the condenser lens. However, when the size of the reflecting mirror is reduced, the light collecting property of the reflecting mirror is reduced, and accordingly, the burden of the refracting power on the collecting lens increases. For this reason, it is necessary to shorten the focal length of the condenser lens.

In order to keep the F value of the condenser lens small when the condenser lens is downsized (in order not to reduce the condenser property), it is necessary to shorten the focal length with a decrease in the lens surface. Good.

Further, in order to greatly change the irradiation angle in a state where the relative position change between the light emitting means comprising the light emitting portion and the reflecting mirror and the condenser lens is reduced, the light emitting means and the condenser lens are brought close to each other. It is better to change the relative position in the state. At this time, it is necessary to shorten the focal length of the condenser lens in order to sufficiently secure the condenser power in the close state.

However, in order to shorten the focal length of the condenser lens, if the focal length of the Fresnel lens is simply shortened, FIG.
As shown in (1), the angle θ of the lens portion 92 becomes large, and as described above, there arises a problem that the light amount loss due to the wall portion 91 connecting the lens portions 92 increases, and the alignment unevenness also increases.

According to the present invention, there is provided a strobe device in which by appropriately setting the shape of both surfaces of a condenser lens, the light loss of the light beam from the light emitting means is reduced, the light beam is effectively used, and the entire device is miniaturized. Aim.

[0013]

According to the present invention, there is provided a strobe device comprising: a light emitting section having a light emitting section; and a reflecting mirror for reflecting a light flux emitted from the light emitting section to a side opposite to a subject side toward the subject side; And a condensing lens for condensing the light beam from the light emitting means and guiding the light to the object side, wherein the light condensing lens has a surface on the object side which is a Fresnel lens surface and a light on which the surface on the light emitting means side is continuous. And a deflecting surface.

[0014]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention, and FIG.
FIG. 3 is an explanatory view of the condenser lens of FIG. 1, and FIG. 3 is an explanatory view showing an optical path state of a light beam passing through a part of FIG.

In FIG. 1, reference numeral 2 denotes a light emitting portion, which is constituted by a strobe flash tube (discharge tube) and has a light emitting surface which is long in the direction perpendicular to the plane of the drawing. Reference numeral 3 denotes a reflecting mirror, which is formed of a curved surface such as an elliptical surface or a paraboloid, and condenses a light beam emitted from the light emitting unit 2 to a side opposite to the object side to converge on the object side (condensing lens 1 side).
Is reflected. The light emitting unit 101 is composed of the light emitting unit 2 and the reflecting mirror 3.

Reference numeral 1 denotes a condensing lens (light projecting lens). One surface 1b is composed of a Fresnel lens surface, the other surface 1a is composed of a continuous light deflecting surface, and in FIG. . As described above, both surfaces of the condensing lens 1 are used as lens surfaces having a condensing function to shorten the focal length, thereby effectively condensing a light beam. The relative positional relationship between the light emitting unit 101 and the condenser lens 1 is made variable by a driving unit (not shown).

In this embodiment, the light beam from the light emitting means 101 is projected through the condenser lens 1 toward the subject. The relative positional relationship between the light emitting unit 101 and the condenser lens 1 is changed by the driving unit along with the zooming of a photographing system (not shown), for example, by changing the interval.
The illuminance angle of the light beam toward the subject is changed.

FIG. 2 is an explanatory view of the condenser lens 1. FIG.
2A is a schematic front view, FIG. 2B is a cross-sectional top view, FIG.
(C) is a side sectional view.

The curved surface 1a of the condenser lens 1 is composed of a convex spherical surface, and the Fresnel lens surface 1b is composed of a concentric Fresnel lens. FIG. 3 shows an optical path of a light beam from a light emitting unit that passes through a part of the condenser lens 1.

In this embodiment, as shown in FIG. 3, the light beam L from the light emitting means enters the curved surface 1a of the condenser lens 1, refracts and enters the Fresnel lens surface 1b. At this time, when the light beam L is incident on the Fresnel lens surface 1b, the angle θ with respect to the reference surface 1c is set to be smaller than that in the case of using the conventional condenser lens shown in FIG.

As a result, the lens unit 1 is subjected to a light deflecting action.
2 is increased. The light flux L ′ shown by the dotted line is incident on the wall surface portion 11 of the Fresnel lens surface 1b and scattered so that the light flux that causes light loss is reduced as compared with the case where the conventional condenser lens of FIG. 8 is used. Thus, the effective use of the irradiation light beam is enhanced.

FIGS. 4 and 5 are explanatory views of Embodiments 2 and 3 of the condenser lens according to the present invention. 4 and 5, (A) is a schematic front view, (B) is a cross-sectional top view, and (C) is a cross-sectional side view.

In the second embodiment shown in FIG. 4, the surface 4a on the light emitting portion side of the condenser lens 4 is constituted by a convex cylindrical lens surface having a light condensing function in the longitudinal direction of the light emitting surface which is a strobe flash tube. 4b is composed of concentric Fresnel lens surfaces.

In general, the stroboscopic flash tube, which is the light emitting surface, has an elongated shape, and the light condensing action of the reflecting mirror 3 in the longitudinal direction is small. Thus, in this embodiment, the convex cylindrical lens surface 4a has a refractive power in the longitudinal direction of the strobe flash tube (light emitting surface) to enhance the light condensing action in the longitudinal direction of the strobe flash tube, thereby improving the irradiation efficiency.

As a result, light loss at the wall surface of the Fresnel lens surface is reduced as in the first embodiment of FIG. 2 while maintaining a predetermined refractive power as a condenser lens.

In the third embodiment shown in FIG. 5, the surface 5a on the light emitting portion side of the condenser lens 5 is constituted by a convex spherical surface, and the surface 5b on the object side is constituted by a convex cylindrical Fresnel lens surface. The convex cylindrical Fresnel lens surface 5b is formed so as to condense light in the longitudinal direction of the light emitting surface, similarly to the convex cylindrical lens surface of the surface 4a of the second embodiment in FIG.

Thus, light loss on the wall surface of the Fresnel lens surface is reduced while securing a predetermined refractive power as a condenser lens, that is, shortening the focus.

FIG. 6 shows a condenser lens according to a fourth embodiment of the present invention.
FIG. In this embodiment, the light deflecting surface of the surface 6a on the light emitting portion side of the condenser lens 6 is formed so that the curvature of the curved surface 6a1 in the central region and the curvature of the curved surface 6a2 in the peripheral region, which are about 30% of the total area thereof, are different from each other. ing. The surface 6b on the subject side is constituted by a concentric Fresnel lens surface or a convex cylindrical Fresnel lens surface.

In this embodiment, the curved surface 6a1 has a substantially infinite (flat) surface, and the curved surface 6a2 has a convex spherical surface or a cylindrical lens surface.

Thus, as in the first embodiment, the light loss on the wall surface of the Fresnel lens surface is reduced while maintaining a predetermined refractive power as a condenser lens.

In each of the above embodiments, the object of the present invention is similarly achieved even if the arrangement of the light deflecting surface and the Fresnel lens surface formed on each surface of the condenser lens is opposite to each other with respect to the light emitting means 101. can do.

[0032]

As described above, according to the present invention, the light loss due to the Fresnel lens surface of the light beam from the light emitting means can be reduced by arranging the shape of both surfaces of the condenser lens disposed in front of the light emitting means as described above. To reduce the amount of light and make effective use of the luminous flux,
Further, it is possible to achieve a strobe device capable of reducing the size of the entire device.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of the condenser lens of FIG. 1;

FIG. 3 is an explanatory diagram of a state where a light beam passes through a part of FIG. 2;

FIG. 4 is an explanatory diagram of Embodiment 2 of the condenser lens according to the present invention.

FIG. 5 is an explanatory diagram of Embodiment 3 of the condenser lens according to the present invention.

FIG. 6 is an explanatory diagram of Embodiment 4 of the condenser lens according to the present invention.

FIG. 7 is an explanatory diagram of a condenser lens used in a conventional flash device.

FIG. 8 is an explanatory view of a part of a condensing lens used in a conventional flash device.

FIG. 9 is an explanatory view of a part of a condenser lens used in a conventional flash device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Condensing lens 1a Light deflecting surface (convex spherical surface) 1b Fresnel lens surface 2 Light emitting part (strobe flash tube) 3 Reflecting mirror 4a Light deflecting surface (cylindrical lens surface) 4b Fresnel lens surface 5a Light deflecting surface (convex spherical surface) 5b Cylindrical Fresnel lens surface 6a1, 6a2 Light deflection surface 6b Fresnel lens surface

Claims (5)

(57) [Claims] 1. A light emitting means having a light emitting portion, a reflecting mirror for reflecting a light beam emitted from the light emitting portion to a side opposite to a subject side toward the subject side, and condensing the light beam from the light emitting portion. A strobe device having a condensing lens for guiding light to the subject side, wherein the condensing lens has a Fresnel lens surface on the subject side and a light deflecting surface on the light emitting means side. apparatus. 2. A light emitting means having a light emitting portion, a reflecting mirror for reflecting a light beam emitted from the light emitting portion on a side opposite to a subject side to a subject side, and condensing the light beam from the light emitting portion. In a strobe device having a condensing lens for guiding light to the subject side, the condensing lens has a Fresnel lens surface on one surface, and a light deflecting surface on the other surface having different curvatures in a central region and a peripheral region. A strobe device characterized by being made of. 3. The flash device according to claim 1, wherein a relative positional relationship between the light emitting unit and the condenser lens is variable, and an irradiation angle from the condenser lens is variable. 4. The strobe device according to claim 1, wherein the Fresnel lens surface is a concentric convex Fresnel lens or a convex cylindrical Fresnel lens having a refractive power in a longitudinal direction of the light emitting portion. 5. The strobe device according to claim 1, wherein the light deflecting surface is a convex spherical surface or a cylindrical lens surface having a refractive power in a longitudinal direction of the light emitting portion.