JPH1039376A - Electronic flashing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the sticking of dust, etc., to a central part by forming a region on which light from a light source arranged in the rear of a Fresnel lens is converged with a reflector and further, whose temp. becomes high with radiant heat, to a shape like consecutive curved surfaces or a plane. SOLUTION: The Fresnel lens 6 is fixed in a casing in the front surface of a light emitting part consisting of the reflector and the light source, the recessed and projection parts of the surface of the lens 6 subdivide the curved surface of the lens into concentric lens curved surface parts 1. Then, each gap between the curved surface parts 1 is connected with wall surface parts 2 and as a whole, formation to a plane shape is attained. Further, the central part 3 of the lens 6 being in the highest degree of a flash and in the positional relation nearest to the light source is constituted to be in the shape like the consecutive curved surfaces or the plane. Thus, the dust, soil, etc., are hardly stuck. Or even if they are stuck, they are easily removed, to prevent the generation of heat caused by the dust, soil, etc., in the conventional manner, the deformation of the lens 6 caused by the generation of the heat, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical panel for controlling a light emission irradiation angle of a photographic strobe device, and more particularly to a Fresnel lens formed by dividing a lens curved surface into a plurality of flat plates.

[0002]

2. Description of the Related Art Hitherto, various Fresnel lenses have been put into practical use as condenser lenses for controlling the emission angle of light emission in a photographic strobe device. Since the Fresnel lens is generally injection-molded or press-molded with an acrylic material, unlike a normal lens mainly made of glass, it does not require surface polishing, is inexpensive, can be mass-produced, and is useful. Applications are expanding.

[0003] Regarding the shape, FIG.
In addition to the rectangle shown in (b), a circle is generally used, and it goes without saying that such a selection is appropriately selected depending on the shape of the light source to be combined and the application. For example, as shown in the plan view and the cross-sectional view in FIGS. 3A and 3B, usually, the structure is such that a lens curved surface is subdivided into a concentric lens curved surface portion 1 and a space between each of the curved curved surface portions 1 is provided. They are connected via the wall surface portion 2 and are formed on a plane as a whole.

As is clear from FIGS. 3 (a) and 3 (b), the Fresnel lens has a wall surface 2 which connects many curved surfaces 1 due to its structure.
As shown in the partial enlarged views of (a) and (b), dust easily enters the intersection of the curved surface portion 1 and the wall surface portion 2, that is, a so-called concave portion, and the entered dust cannot be easily removed. In addition, there is a disadvantage that dust such as hand dust easily adheres to the projections.

As shown in FIG. 4, the Fresnel lens collects the flash light from the light source directly or the reflected flash light reflected by the reflector, and irradiates the collected light to a subject at a long distance. Therefore, not only a spherical light source, but also a rod-like light source such as a xenon tube, the flash or radiant heat is concentrated near the center of the Fresnel lens.
The dust that enters the intersection of the curved surface portion 1 and the wall surface portion 2 of the Fresnel lens, that is, the so-called concave portion, or the dust such as the dirt attached to the convex portion generates heat due to the above-mentioned condensing or radiant heat of the flash light, and further burns. However, there is a problem that the fresnel lens is deformed and scorched due to the heat that is scorched, thereby deteriorating the characteristics.

[0006] With the recent miniaturization of the flash device, as the flash portion is made smaller, the distance between the light source and the Fresnel lens becomes closer, and the influence of the above-mentioned heat generation due to the collection of the flash light and radiant heat is further increased. Has problems.

[0007]

However, the central portion of the above-mentioned conventional Fresnel lens is the curved surface portion 1 described above.
Dust that has entered the intersection of the wall portion 2 and the so-called concave portion, or dust such as grit attached to the convex portion generates heat due to the above-mentioned condensing or radiant heat of the flash light, and is scorched. Or, there is a problem that charring occurs and characteristics are deteriorated.

Further, with the recent miniaturization of the flash device, the distance between the light source and the Fresnel lens becomes shorter, and the above-mentioned heat generation due to the collection of the flash light and the influence of the radiant heat are further increased. The present invention has been made in consideration of the above-described problems, and in order to prevent dust from adhering to a central portion of the Fresnel lens, that is, heat generated by light collection, or a region that becomes high temperature due to radiant heat. A flash device which does not cause a problem that the central portion of the above-mentioned region is formed into a continuous curved surface or a planar shape, and heat is generated by the above-mentioned condensing or radiant heat of the flash and is burnt, and further, deformation of the Fresnel lens or deterioration of characteristics is not caused. The purpose is to do.

[0009]

In order to solve the above-mentioned problems, the flash device according to the first aspect of the present invention has a large number of curved lens surfaces connected to one side surface of a flat plate via a wall surface. A Fresnel lens in which a lens curved surface portion is formed, in which light from a light source disposed behind the Fresnel lens is condensed by a reflector, and further, a region that becomes high temperature due to radiant heat is formed into a continuous curved surface or a planar shape. Thus, a Fresnel lens is constructed.

Thus, a Fresnel lens in which dust and the like do not adhere to the central portion of the light emitting section can be obtained, and further, an effect that the size can be reduced as compared with the related art can be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a Fresnel lens having a lens curved surface formed by subdividing a large number of lens curved surfaces connected to one side surface of a flat plate via a wall surface. There is a Fresnel lens, characterized in that light from a light source disposed behind the Fresnel lens is collected by a reflector, and further, a region that becomes high in temperature due to radiant heat has a continuous curved surface or a planar shape. It has an effect of preventing dust from adhering to the high-temperature region, causing scorching, and causing no deformation or deterioration of characteristics of the Fresnel lens.

According to a second aspect of the present invention, there is provided a Fresnel lens having a lens curved surface portion formed by subdividing a large number of lens curved surfaces connected to one side surface of a flat plate via a wall surface portion,
The light of the light source disposed behind the Fresnel lens is collected by a reflector, and further, the region where the temperature becomes high due to radiant heat is provided with a Fresnel lens characterized by having a continuous curved surface or planar shape. The electronic flash device has an effect of preventing dust from adhering to the high-temperature area, causing scorching, and causing no deformation or deterioration of characteristics of the Fresnel lens.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment) FIG. 1 and FIG. 2 show a schematic plan view and a schematic sectional view of a main part of an electronic flash device according to an embodiment of the present invention. The mechanism is shown. As shown in FIGS. 1 and 2, the electronic flash device according to the present embodiment basically includes a flash discharge tube, for example, a xenon tube (hereinafter referred to as Xe) 4 as a light source for emitting a flash, and a flash for the flash. It comprises a reflecting umbrella 5 that reflects light, and is composed of a Fresnel lens 6 that condenses the flash light in order to efficiently irradiate the direct light from the Xe tube 4 and the reflected light of the reflecting umbrella 5 to an irradiation target.

The Fresnel lens 6 shown in FIGS. 1 and 2 is fixed to a housing (not shown) on the front surface of the light-emitting section composed of the reflector 5 and the light source 4. The lens curved surface is subdivided into concentric lens curved surface portions 1, and the curved surface portions 1 are connected to each other via a wall surface portion 2, and are formed on a plane as a whole. The central portion 3 of the Fresnel lens 6, which is the highest and the light source has the closest positional relationship, is formed of a continuous curved surface or planar shape.

In the above configuration, as shown in FIG. 2, the flash light emitted from the light source 4 is directly radiated to the Fresnel lens 6 and the light reflected by the reflector 5 is transmitted to the Fresnel lens 6. When the light emitted from the light source 4 is emitted to the central portion 3 of the Fresnel lens 6, the region of the central portion 3 of the Fresnel lens It can be easily understood that the temperature rise is larger than that in the peripheral region.

Further, since the light source 4 is disposed at the position closest to the center of the Fresnel lens 6 due to the structure of the flash device, the radiant heat of the light source 4 causes the heat of the center of the Fresnel lens 6 to be similar to the flash. As a result, the temperature rise caused by the radiant heat and the temperature rise caused by condensing the flash light are synergized, and the central portion 3 of the Fresnel lens 6 is in a high temperature state. As shown in FIGS. 1 (a) and 1 (c), the central portion 3 of 6 has a curved surface or a planar shape with no irregularities, so that it is difficult for dust or hand marks to adhere thereto. Because of the shape that can be easily removed, there is an effect that it is possible to provide an electronic flash device in which heat generated by conventional dust or hand marks, or deformation of the Fresnel lens due to the generated heat does not occur.

[0017]

As described above, the electronic flash device of the present invention is
A Fresnel lens in which a lens curved surface portion formed by subdividing a large number of lens curved surfaces connected to one side surface of a flat plate via a wall surface portion is formed, and light from a light source disposed behind the Fresnel lens is reflected by a reflector. A Fresnel lens characterized by being condensed and further heated to a high temperature by radiant heat into a continuous curved surface or a planar shape, or an electronic flash device including the Fresnel lens, whereby the central portion is formed. Can obtain a Fresnel lens to which dust and the like do not adhere.

[0018] Accordingly, since there is no seizure, burning or deformation even at the above-mentioned high temperature, the effect that the size can be reduced as compared with the conventional one can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic plan view and cross-sectional view of a Fresnel lens showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an electronic flash device showing the embodiment.

FIG. 3 is a schematic plan view and a sectional view of another conventional Fresnel lens.

FIG. 4 is a schematic configuration diagram showing an embodiment of another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Curved surface part 2 Wall part 3 Central part 4 Light source 5 Reflector 6 Fresnel lens

Claims (2)

[Claims] 1. A Fresnel lens having a lens curved surface portion formed by subdividing a large number of lens curved surfaces connected to one side surface of a flat plate via a wall surface portion, wherein a light source disposed behind the Fresnel lens is provided. Light is collected by the reflector, and
The Fresnel lens is characterized in that the region that is heated by radiant heat has a continuous curved surface or planar shape. 2. A Fresnel lens in which a lens curved surface portion obtained by subdividing a large number of lens curved surfaces connected to one side surface of a flat plate via a wall surface portion is formed, and a light source disposed behind the Fresnel lens. Light is collected by the reflector, and
An electronic flash device equipped with a Fresnel lens, characterized in that a region which becomes high in temperature due to radiant heat has a continuous curved surface or a planar shape.