JPH01198708A - Projection optical system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical field to which the invention is directed] This invention relates to a light projection optical system for guiding a light beam projected from a halogen lamp to a light guide constituted by a bundle of optical fibers. Application is possible.

[Prior art]

Because halogen lamps emit light that is very similar to white light, they are preferred for more accurate color recognition.
Since a is on its optical axis, it usually has a reflection of -3, and the light is reflected efficiently (in front of it) by this reflecting mirror.

In this figure, there is only an elbow-like amount of light in the vicinity of the base axis near the lamp 2, so the photoelectric distribution becomes as shown in Figure 3A. On the other hand, as shown in Figure B, a light point with a large amount of light is obtained near the focal point, or the angle between the optical axis of each light ray is the same as in other parts, so the end of the light guide consisting of the original fiber bundle is placed at that point. If you leave it behind,
The light spot emitted from the other end of the light guide also has an annular shape.Since the light beam is focused on the optical axis of the light guide 2, its luminous flux distribution changes as shown in C and D in the figure as it moves farther away.

Therefore, in order to avoid the phenomenon in which the shape of the projected light spot becomes annular, a convex lens 5 is arranged on the light shelf of the VC lamp 20 at a position away from the focal point as shown in FIG. Moto Higashi corrected to almost parallel light? There is a method of letting the light enter the light guide 1, or a method of arranging a concave lens 6 at a position before the focal point for the same purpose as shown in FIG.

[Problems to be solved by the present invention] In the case shown in FIG. 4 or 5, it is necessary to hold the lens 5.6, and the structure becomes complicated, resulting in an increase in the number of parts. Another disadvantage is that when assembled as a device, the structure becomes larger as a whole.

OBJECTS OF THE INVENTION] In view of these conventional drawbacks, it is an object of the present invention to provide a uniform light projection spot to a light guide VC without using optical components such as lenses.

[Structure of the invention]

In order to achieve the object of the present invention, the optical axis of the halogen rung is also inclined at a predetermined angle with respect to the optical axis of the light guide.

As a result, the straight direction of the brightest beam in the annular beam formed by the halogen lamp coincides with the optical axis of the light guide.

Therefore, a uniform light projection spot with a large amount of light can be obtained at the end of the light guide.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

That is, in FIG. 1, the light guide 1 is composed of a plurality of optical fibers. Further, the halogen lamp 2 has a reflecting mirror 3. The halogen lamp is arranged so as to be inclined by a predetermined angle θ with respect to its axis, that is, the optical axis of the fine light guide. It is thought that the brightest component, that is, the main luminous flux, lies on a certain conical surface in the halogen lamp, and therefore it is highly efficient to place the optical axis of the light guide l on that conical surface. It is from. In other words, it is sufficient to set the inclination angle θ of the optical axis of the halogen lamp 2 with respect to the optical axis of the light guide l to be the apex angle of the cone. Since the principal ray, which is one side of the main beam, coincides with the optical axis of the light guide 1, no annular light projection spot is generated at the other end of the light guide.

Note that the principal ray group other than the optical axis of the halogen rung 2, that is, the principal ray flux, also enters the light guide 1, but the light guide 1 has a property that the incident efficiency decreases as the incident angle increases, so this has a small effect on the projected light spot. It is not a component that gives a certain amount of energy, but rather works to make the whole uniform.

Further, the angle σ of the halogen lamp 2 relative to the light guide 1 may be made movable to account for variations in the halogen lamp 2 or other factors. The optimum position can be easily determined while keeping the position of l fixed.

A heat ray attenuation filter 4 for attenuating heat rays generated by the halogen lamp 2 is provided between the halogen rung 2 and the light guide 1.

〔Effect of the invention〕

In this invention, as described above, the optical axis of the halogen lamp is inclined at a predetermined angle with respect to the optical axis of the light guide, so that the brightest luminous flux component in the ring of the annular luminous flux is transmitted to the light guide. The light is incident almost coincident with the optical axis, and therefore a uniform light projection spot can be obtained at the other end of the light guide. Not only that, but the number of parts such as lenses has increased (there is no advantage).

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of the light projection optical system according to the present invention, FIG. 2 is a side view showing the light projection curve of a halogen lamp, and FIG. 3 is a characteristic curve diagram at each point in FIG. 2. , 4 and 5 are side views showing a conventional light projection optical system. 1...Light guide, 2...Halogen rung, 3.
... Reflector, 4... Heat ray attenuation filter. Patent applicant: Yamatake Honeywell Co., Ltd.
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Claims (1)

[Claims] The light guide comprises a halogen lamp having a reflecting mirror, a light guide constituted by an optical fiber bundle, and a heat ray attenuation filter provided between the light guide and the halogen lamp to reduce heat rays to the light guide. One end of the halogen lamp is disposed near the focal point of the light beam from the halogen lamp, and the halogen lamp is disposed with its optical axis inclined at a predetermined angle with respect to the optical axis of the light guide. Optical optical system.