JPH09222580A - Converging reflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a converging reflector improved incolor evenness and luminance evenness and having high convergent efficiency of irradiation light. SOLUTION: A reflection surface consists of division surfaces 11 -14 ... in the rotational (peripheral) direction and the axial (concentric circular) direction. The reference shape of the reflector is in an elliptic surface shape, and respective reflection surfaces constituting the reflector are constituted having a certain tilt for the reference elliptic shape, and converging positions are set by the tilts of respective reflection surfaces. A converging range being a circle generally lighting on a surface to be irradiated is set in different points in convergent positions in the respective rotational direction, and a lighting range in the surface to be irradiated is able to be converged so as to approach no a square shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a condensing reflector, and more particularly to a condensing reflector used in various optical systems such as liquid crystal projectors to improve projection characteristics.

[0002]

2. Description of the Related Art An example of a conventional light collecting reflector of this type is shown in FIG. 7, which shows a light collecting reflector having a paraboloidal rotating surface as a reflecting surface. In FIG.
The light emitted from the light source 12 is reflected by the condensing reflector 11 and applied to the illuminated surface 13. At this time, the illuminance distribution on the illuminated surface 13 is generally shown in FIG. 7 depending on the light emission distribution of the light source 12 of the lamp, the shape of the condenser reflector 11, and the like.
As shown on the right side of the figure, the illuminance distribution has a characteristic that the central part is bright and the peripheral part is dark. Further, since the reflecting surface of the condensing reflector 11 has a rotationally symmetrical shape, the shape of the illumination range on the illuminated surface is circular as shown in FIG.

As a conventional example, as shown in FIG. 9, a condensing reflector composed of a plurality of ring-shaped mirror surfaces corresponding to different portions of a paraboloid of revolution (Japanese Patent Laid-Open No. 2-259).
No. 713). In FIG. 9, the reflector is a condensing device composed of _n ring-shaped mirror surfaces 11 _{1 to} 11 _n , and each ring-shaped mirror surface has a structure in which the center axes of the ring zones are aligned. In this reflector, with respect to the focal position F ₁ of the mirror 11 _1, the focal position F ₂ the mirror 11 ₂ are inward, and, with respect to the focal position F ₂ the mirror 11 _2, the focus position F _n of the mirror surface 11 _n Mirror surfaces 11 ₁ , 11 ₂ , 11 _n to come inside
Has been arranged. As a result, the illuminance distribution on the surface to be illuminated (illuminance in the periphery with respect to the illuminance in the center) can be improved to some extent, and it also has the effect of reducing unevenness in color and unevenness in illuminance of the light emitting section of the light source. There is. However, in the case of this example, since the reflecting mirror surfaces 11 _{1 to} 11 _n are ring-shaped,
Concerning the above-mentioned illuminance distribution and color unevenness, it is not possible to completely improve the distribution and unevenness that occur in a concentric circle shape. Further, the shape of the illumination range on the illuminated surface is circular as in the above example, and the reduction of the light collection efficiency at this point cannot be improved.

[0004]

SUMMARY OF THE INVENTION In the conventional technique of this kind of condensing reflector as described above, the illuminance distribution on the illuminated surface has a characteristic that the center is bright and the periphery is dark, and uniform illuminance characteristics are obtained. I can't. Further, since the light emitting portion of the light source usually has color unevenness and brightness unevenness, the color unevenness,
Brightness unevenness appears on the illuminated surface. In addition, since the illuminated area on the illuminated surface is circular (see FIG. 8), the illuminated light is not effectively used on the screen where the illuminated surface is usually rectangular (see FIG. 8). In addition, the shaded area caused by the difference between the circular shape of the irradiation range and the rectangular shape of the surface to be irradiated) is a major factor that reduces the light collection efficiency. The present invention has been made in view of the above problems in the prior art, and an object of the present invention is to provide a light condensing reflector with improved color non-uniformity and brightness non-uniformity and high irradiation light condensing efficiency.

[0005]

According to a first aspect of the present invention, in a condensing reflector having a reflecting surface shape as an elliptical rotation surface, a reference split surface obtained by dividing one elliptical rotation surface into a plurality of surfaces. By changing the inclination with respect to the reference plane for each of the divided surfaces so that the surface formed after the change constitutes a reflecting surface, and changing the condensing position of each of the divided surfaces, the shape of the illuminance distribution on the irradiated surface Can be arbitrarily designed.

According to a second aspect of the invention, in the first aspect of the invention, the plurality of surfaces are divided in the rotation (circumferential) direction of the reference elliptical rotation surface, and the irradiation distribution on the surface to be irradiated is determined. This makes it easier to design the shape.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the plurality of surfaces are divided in the direction of the axis (concentric circle) of the reference elliptical rotation surface, and the surface to be irradiated is This makes it easier to design the irradiation distribution shape.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the inclination of the divided surface is changed so as to focus light in accordance with a predetermined shape of the illuminated surface, According to the reference elliptical rotation surface, it is possible to improve the light collection efficiency by changing the irradiation distribution so that the illumination range becomes circular and corresponds to a normal rectangular screen.

[0009]

1 is a diagram showing an embodiment of a light collecting reflector of the present invention. In this embodiment, FIG.
As shown in (B), the reflecting surface of the condenser reflector is divided into respective surfaces cut in the rotational (circumferential) direction and the axial (concentric) direction. In addition, about this division method,
Other than this, a method of dividing each divided surface with the same shape, a method of dividing only in the circumferential direction, a method of dividing only in the axial direction, and the like can be considered. The basic shape of this reflector is a spheroidal surface. That is, the curve indicated by the chain double-dashed line in FIG. 1 (A) has an elliptical shape, so that each reflecting surface forming the reflector is formed with a certain inclination from this reference elliptical shape. FIG. 2 shows a light collecting state of the reference spheroidal reflector 1 '. In FIG. 2, the light source 2
The emitted light is reflected by the condenser reflector 1 ′ and gathers at one point on the illuminated surface 3. In the example of the present invention, the reference spheroidal reflector surface is divided, and the divided reflecting surfaces are provided with different inclinations, whereby the light condensing position on the illuminated surface is freely designed. It is characterized by that.

FIG. 3 shows a view of an example of this reflector as seen in a cross section passing through the optical axis. In FIG. 2, the light emitted from the light source 2 is reflected by each reflection surface of the reflector and condensed on each surface of the irradiated surface 3 at one point, but in the embodiment of the present invention, the inclination of each reflection surface is changed. Since each is changed, the focusing position is different from the case of the spheroidal reflector, and the focusing position is to a point corresponding to the inclination of each reflecting surface. In FIG. 3, the light reflected by each of the reflecting surfaces 1 ₁ , 1 ₂ , 1 ₃ and 1 ₄ is condensed at each position of the illuminated surface. In FIG. 4, the light collection positions on the illuminated surface are represented as points and the distribution thereof is shown. Note that, and in FIG. 4 correspond to the same reference numerals in FIG. 3, and are collected from the reflecting surfaces 1 ₁ , 1 ₂ , 1 ₃ and 1 ₄ in FIGS. 1B and 3 respectively. It shows the light position. The condensing position shown in FIG. 4 can be set by the inclination of each reflecting surface. Therefore, according to the shape of the condensing range of the irradiated surface (in this example, the condensing position is rectangular), the condensing position is different in each rotation direction, and as a result, the irradiated surface is changed. It is possible to focus the illumination range at to a rectangular shape. Further, the condensing position in each rotation direction can be designed freely by designing the position interval according to the demand of the illuminance distribution on the illuminated surface. The illuminance distribution on the illuminated surface can be made uniform by design.

In the above description, the light source is basically a point light source, but in reality, the light emitting source is not a perfect point light source but has a certain size. In FIG. 5, the light reflected by each reflecting surface by the light emitting source having a certain size is
It is a figure which shows how it is irradiated by the to-be-irradiated surface. Note that ,, and in FIG. 5 correspond to the same symbols in FIG. As shown in FIG. 5, actually, on the illuminated surface, the light reflected by each surface is emitted while overlapping.
The distribution of the surface to be illuminated as shown in this result can also be dealt with so as to be uniform by changing the inclinations of the reflecting surface as described above. Next, an example of how to attach the inclination of each reflecting surface is shown. FIG. 6 is a diagram for explaining that the elliptical surface is rotated and tilted about a focus (light source position). In FIG. 6, the elliptical surface of rotation indicated by the solid line and the position and light ray after the light ray is rotated by θ around the focal point (light source position) are indicated by broken lines. Further, as another tilting method, a method of rotating the center of each reflecting surface as a rotation axis may be used.

[0012]

According to the invention of claim 1, the inclination of each reflecting surface obtained by dividing the elliptical surface of revolution is changed from the reference plane,
It is possible to eliminate the color unevenness and brightness unevenness that have been caused by the condensing reflector having the conventional rotationally symmetrical reflecting surface, and the illumination range on the illuminated surface can also be adjusted.
It can be changed to obtain any distribution from the conventional circle.

According to the invention of claim 2 or 3, in addition to the effect of claim 1, by dividing the dividing surface in accordance with the geometrical properties of the elliptical surface of revolution, the reflecting surface is easy to design and easy to make. The reflector with is provided.

According to the invention of claim 4, in addition to the effects of claims 1 to 3, as an illumination range on the surface to be illuminated,
For example, even when a predetermined shape such as a rectangle is required, it is possible to easily meet the request by adjusting the divided elliptical rotation surface and its inclination.

[Brief description of drawings]

FIG. 1 is a sectional view (A) and a front view (B) of an embodiment of a light collecting reflector having a spheroidal reflecting surface of the present invention.

FIG. 2 is a diagram showing a light collecting state at a reference ellipsoidal reflector.

FIG. 3 is a diagram showing a cross-sectional view of an embodiment of a light collecting reflector of the present invention together with working light.

FIG. 4 is a diagram conceptually showing a condensing state of a surface to be illuminated by an embodiment of a condensing reflector of the present invention.

FIG. 5 is a diagram for explaining a light collecting state of an illuminated surface according to an embodiment of a light collecting reflector of the present invention.

FIG. 6 is a diagram for explaining how to incline a reflecting surface in an embodiment of a light collecting reflector of the present invention.

FIG. 7 is a diagram showing a conventional example of a condensing reflector of this type in which a reflecting surface shape is a paraboloidal rotating surface.

FIG. 8 is a diagram showing a conventional illumination range on a surface to be illuminated.

FIG. 9 is a diagram showing a conventional example of a light collecting reflector having a rotating paraboloid as a reflecting surface.

[Explanation of symbols]

1 '... spheroidal reflector 1 ₁ , 1 ₂ , 1 ₃ , 1 ₄
... Reflecting surface, 2 ... Light source, 3 ... Irradiation surface, 11 ... Condensing reflector, 11 _{1 to} 11 _n ... Ring-shaped mirror surface, 12 ... Light source, 13
... illuminated surface, F ₁ to F _n ... focal position.

Claims (4)

[Claims] 1. A condensing reflector having a reflecting surface shape as an elliptical rotation surface, wherein a reference surface is tilted with respect to each of the division surfaces obtained by dividing a reference one elliptical rotation surface into a plurality of surfaces. A condensing reflector characterized in that a reflecting surface is constituted by a surface formed after the change. 2. The condensing reflector according to claim 1, wherein the plurality of surfaces are divided in a rotation (circumferential) direction of a reference one elliptical rotation surface. 3. The condensing reflector according to claim 1, wherein the plurality of surfaces are divided in a direction of an axis (concentric circle) of a reference one elliptical rotation surface. 4. The condensing reflector according to claim 1, wherein the inclination of the divided surface is changed so as to condense light according to a predetermined shape of the irradiation surface.