JPH01267601A - Condenser lens - Google Patents

Abstract

PURPOSE:To improve the light condensing efficiency of an electronic flash device, etc., by forming a reflecting surface which totally reflects the light from a light source in a photographing range to the edge of the lens and forming an incident face which guides the light from the light source to the reflecting surface in the position adjacent to said reflecting surface. CONSTITUTION:The reflecting surface S2 which totally reflects the light form an electric discharge tube 1 to the inside of the photographing range is provided to the edge of the condenser lens and the incident surface S1 for guiding the light from the discharge tube to the reflecting surface S2 is provided in the position adjacent to the reflecting surface S2. The incident surface S1 has the inclination reverse from the refracting face (Fresnel face) of the condenser lens 4 and projects the light from the discharge tube 1 to the reflecting surface S2 at such an angle at which the light reflects totally on the reflecting surface S2. Namely, the ray emitted from near the center of the discharge tube 1 and enters the incident surface S1 is so refracted as to be reflected at a suitable incident angle by the reflecting surface S2 and is directed to the photographing range after the light is reflected by the reflecting surface S2. The light which is heretofore reflected by a reflecting shade near the edge of the condenser lens 4 and escapes to the outside of the photographing range can be directed to the inside of the photographing range and, therefore, the condensing efficiency of the electronic flash device, etc., is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a condenser lens used in a strobe device of a camera, etc.

(Prior Art) A strobe device for a small camera generally consists of a cylindrical discharge tube and a reflector that surrounds the discharge tube leaving an irradiation opening, and the light from the discharge tube is directly transmitted.

Alternatively, after being reflected by a reflective umbrella, the light is irradiated from the irradiation port toward the subject. The irradiation port has a rectangular shape, and in the direction of the short side, one reflective umbrella has a certain amount of light focusing effect, and in the long side direction, it is difficult to collect light with only one reflective umbrella, so the irradiation [1] It is normal to use lenses to collect light. A Fresnel lens is often used as a condensing lens, and the groove shape of the Fresnel lens may be linear or ring-shaped.

However, with a condensing lens like this.

The distance layer from the light emitting part (discharge tube) to the refractive surface of the lens is short compared to the long side dimension, so even if you use a Fresnel surface to strengthen the refractive power, the diverging light cannot be focused within the angle of view. There were limits to what he could do.

That is, as shown in FIG. 4, when considering the light rays R1 to R5 emitted from the vicinity of the center of the radiation tube 1, only two, R1 and R2, head toward the interior of the mountain.

R3 goes outside the angle of view because the Fresnel surface of the condensing lens 2 lacks refractive power, and R4 is not a refractive surface.
It hits the wall 2a and spreads.

In addition, since the light ray R reflected on the side surface of the reflective umbrella 3 is directed toward the Fresnel surface 2b or in a direction that has a diverging effect, it also goes outside the artist, where the refractive power of the Fresnel surface is strongly increased. For example, is it possible to direct the light ray R into the angle of view?
If you do so, more of the rays will be incident on the wall than on the Fresnel action surface, and the effect will not be as expected.

(Purpose and configuration of 1!1) , (The purpose of 1.1 is that fjJ was created in view of the points mentioned in 1., and its purpose is to improve the light condensing effect of strobe devices, etc.). In order to achieve this goal, a reflective surface is formed at the edge of the condensing lens that completely reflects the light from the light source within the angle of view, and a reflective surface is placed adjacent to this reflective surface to direct the light from the light source to the reflective surface. It was configured to form an incident surface that guides the light.

(-2, ra-color example) More unreleased +! 1 will be explained based on the drawings.

1st L! J is a cross section 1i1 of the condensing lens '--Example due to unreleased IJI.

In the IA, reference numeral 4 is a condenser lens using Fresnel lenses, and near the center of the condenser lens 4 there is a condenser lens (the fourth
14) The refractive power is i- in the long side direction,) -1) A straight Fresnel surface is formed. However, at the edge of the condensing lens 4, there is a reflecting surface S2 that totally reflects the light from the discharge tube l into the angle of view, and at a position adjacent to this reflecting surface S2, the light from the discharge tube is reflected. An incident surface Sl is formed for guiding the light to the surface S2. Incidence surface S.

is the inclination opposite to the refractive surface (Fresnel surface) of the condenser lens 4.
The light is emitted at a corner where the light is totally reflected by the reflective surface S2.
lr, the light from the tube l is emitted onto the reflecting surface S2''\t1'.

If configured as shown in 2, 1, likely m, R, -R
4 passes through the same path as in FIG. In order to utilize
The light beam incident on 1 becomes i+! on the reflecting surface S2. It is refracted so as to be reflected at a proper incident angle, and after being totally reflected by the reflecting surface S2, it heads into the field of view. Here, assuming that the light source is located at the center of the discharge tube 1, even if the light source deviates from the center by one angle, the light that is incident on the incident surface S1 at the same angle as the light ray R6 will be directed within the angle of view. Ru. Furthermore, considering that a light beam reflected once backward, such as the light beam R6, can also be used, the effects of the present invention are significant.

7fS2[J is a partial enlarged view of the right edge of the condensing lens 4. If the angle between the incident surface S1 and the reflective surface S2 is θ, the angle θ satisfies the following conditions: It is preferable to make an island.

0<50' When θ becomes smaller beyond this condition, the light from the discharge tube I enters the incident surface S almost directly, and the angle of incidence on the reflecting surface S2 becomes smaller. Therefore, the light after total reflection goes outside the angle of view as shown by i 3 fM 9 (Effects of the Invention) As explained above, according to the present invention, the light from the light source is attached to the edge of the condenser lens. By forming a reflective surface that totally reflects the light within the angle of view, and by forming an incident surface adjacent to this reflective surface that guides the light from the light source to the reflective surface, it is possible to The light that was reflected by the reflector near the edge of the condensing lens and escaped outside the field of view can be directed into the field of view, improving the light collection efficiency of a strobe device. can.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the condensing lens according to the present invention, FIG. 211 is a partial enlargement of the right edge of the lens (A), FIG. Fig. 4 is a sectional view showing a conventional condensing lens. 1...Discharge tube, 2.4...Condensing lens, 3...Reflector, SI...Incidence surface, S2... reflective surface

Claims (1)

[Claims] In a condensing lens having a refractive surface for condensing light from a light source into an angle of view, a reflective surface is formed at the edge of the lens to totally reflect light from a light source into an angle of view, and this reflective surface A condensing lens characterized in that an incident surface for guiding light from a light source to the reflecting surface is formed at a position adjacent to the condensing lens.