JPH07288018A - Lighting device - Google Patents

Abstract

PURPOSE:To provide a lighting device having the increased utilization efficiency of light radiated from a light source without causing enlargement and complication of the device and requiring no complex adjustment. CONSTITUTION:Light from a light source 12 is reflected as a light beam in nearly parallel toward the front by a paraboloidal mirror 11. The light outgoing to an opening 22 out of a parallel light beam transmits the opening 22 as it is at the opening 22 of a plane mirror 17 in the front to reach a body to be illuminated to illuminate it. The light outgoing to the reflecting surface of the plane mirror 17 is reflected to be incident onto the paraboloidal mirror 11 with the neary parallel light beam kept. The light is reflected toward a focus part 11a on the reflecting surface of the parabolic mirror 11 to pass through the focus part 11a to be incident onto the reflecting mirror, and becomes a neary parallel light beam again to transmit the opening 22 to reach the body to be illuminated, and illuminates it. Since light in a specific light wavelength region out of light radiated from the light source 12 is transmitted or absorbed by the paraboloidal mirror 11 and the reflecting surface of the plane mirror 17, illumination can be performed by a light suited to the body to be illuminated and having an optional and desired light wavelength region.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device suitable for a projection optical system and having improved light utilization efficiency.

[0002]

2. Description of the Related Art Conventionally, in a lighting device used in a projection optical system such as a liquid crystal projector or an overhead projector, in order to efficiently irradiate the light emitted from the light source, the light source is provided with a reflecting surface such as a parabolic surface or an elliptical surface. It is configured in combination with the concave mirrors it has, or in combination with a condenser lens provided in front of these concave mirrors.

A conventional lighting device is constructed as shown in FIGS. 6 to 9, for example.

First, the illuminating device shown in FIG. 6 uses a parabolic mirror 1 as a reflector, and a light source 2 is arranged at or near a focal position 1a of the parabolic mirror 1. The light from the light source 2 is reflected by the parabolic surface of the parabolic mirror 1 to form a substantially parallel light beam, which is projected forward to illuminate the illuminated object 3 such as a film or a liquid crystal light valve.

In the illuminating device shown in FIG. 6, of the light emitted from the light source 2, only the light caught by the reflecting surface of the parabolic mirror 1 is guided to the illuminated body 3. Is. Further, since the luminous flux emitted to the outside of the area shape of the illuminated body 3 does not enter the illuminated body 3, the utilization efficiency of the light emitted from the light source 2 is low. Therefore, the illuminated object 3
The illuminance becomes low and a good projection image cannot be obtained.

Therefore, in order to improve the utilization efficiency of light,
Although it is possible to shorten the focal length of the parabolic mirror 1,
Considering the constraints due to the shapes of the light source 2 and the parabolic mirror 1 and the constraints due to heat, it is difficult to obtain sufficient utilization efficiency in a practical range.

Further, the illuminating device shown in FIG. 7 uses an ellipsoidal mirror 5 as a reflector, and the ellipsoidal mirror 5 has a first focus position 5a or a light source 2 near the first focus position 5a.
And a condenser lens 6 is provided near the second focus position 5b of the ellipsoidal mirror 5 and at a position farther from the second focus position 5b when viewed from the light source 2. And the light source 2
The light radiated from is condensed by the reflecting surface of the ellipsoidal mirror 5 at the second focal position 5b or in the vicinity of the second focal position 5b, then diverges and enters the condenser lens 6, and is substantially radiated by the condenser lens 6. It becomes a parallel light flux and illuminates the illuminated body 3.

The illuminating device shown in FIG. 8 uses an ellipsoidal mirror 5 as a reflector similarly to the illuminating device shown in FIG. 7, and the first focal position 5a of the elliptic mirror 5 or the first focal position 5a thereof. Although the light source 2 is arranged in the vicinity of, the divergent condenser lens 7 is provided in the vicinity of the second focus position (not shown) and in a position closer to the second focus position when viewed from the light source 2.
Then, the light emitted from the light source 2 is condensed toward a second focal position (not shown) by the reflecting surface of the ellipsoidal mirror 5, and is provided near the second focal position when viewed from the light source 2. Since it enters the divergent condenser lens 7, the divergent condenser lens 7 forms a substantially parallel light flux to illuminate the illuminated body 3.

In the illumination device shown in FIGS. 7 and 8, all the light emitted from the light source 2 and reflected by the ellipsoidal mirror 5 used as a reflector is stored in the condenser lens 6 or the divergent condenser lens 7. The light emitted from the light source 2 is used more efficiently because the light is guided to the light source and is illuminated on the illuminated body 3 as substantially parallel light fluxes.

However, since the condenser lens 6 or the divergent condenser lens 7 is used as described above, a constant spatial distance is required. Further, it is necessary to provide a focus adjusting mechanism for the condenser lens 6 or the divergent condenser lens 7, which leads to an increase in size and complexity of the illumination device.

The illuminating device shown in FIG.
No. 40223, the ellipsoidal mirror 5 is used as a reflector as in the illumination device shown in FIG.
The first focal position 5a or the first focal position 5a of this ellipsoidal mirror 5
The light source 2 is arranged in the vicinity of the second focus position, the condenser lens 6 is provided in the vicinity of the second focus position 5b at a position far from the light source 2, and the concave mirror 8 is further provided.

The concave mirror 8 has a radius of curvature substantially equal to the focal length of the ellipsoidal mirror 5, and the center point of this radius of curvature is in a positional relationship such that it is substantially coincident with the first focal position 5a of the ellipsoidal mirror 5. Will be placed. An opening 8a is provided in a part of the concave mirror 8, that is, a part corresponding to the second focus position 5b.

In the illuminating device shown in FIG. 9, like the illuminating device shown in FIG. 7, the light emitted from the light source 2 is caught by the ellipsoidal mirror 5, and the reflecting surface of the ellipsoidal mirror 5 is reflected. All the light reflected by is the aperture where the second focus position 5b is located.
The light is focused on the portion 8a, passes through the opening 8a, then diverges and enters the condenser lens 6. Then, the condenser lens 6 forms a substantially parallel light beam to illuminate the illuminated body 3.

Of the light emitted from the light source 2, the light not caught by the ellipsoidal mirror 5 is caught by the reflecting surface of the concave mirror 8 as shown in the drawing, and the first focal point position 5a where the light source 2 is located. Reflected towards. The reflected light passes through the first focal point position 5a and then enters the reflecting surface of the ellipsoidal mirror 5. Here, all the light that is incident on the ellipsoidal mirror 5 and reflected by the reflecting surface of the ellipsoidal mirror 5 is condensed at the second focal position 5b, so that the aperture 8a where the second focal position 5b is located is The light passes through the condenser lens 6 and enters the condenser lens 6, and the condenser lens 6 forms a substantially parallel light beam to illuminate the illuminated body 3.

However, in the illuminating device shown in FIG. 9, of the light emitted from the light source 2, the light not radiated to the ellipsoidal mirror 5 is also guided to the illuminated body 3, so that the light utilization efficiency is improved. However, on the other hand, the lighting device is complicated and the adjustment of each reflecting mirror is complicated.

[0016]

As described above, in the conventional illuminating device, the utilization efficiency of the light emitted from the light source is not sufficient, and the one having the improved utilization efficiency of the light is large and complicated. However, there is a problem in that it causes complication due to the adjustment and various adjustment work.

An object of the present invention is to provide an illuminating device which enhances the utilization efficiency of the light emitted from the light source without increasing the size and complexity of the device and requiring no complicated adjustment.

[0018]

An illuminating device according to claim 1 has a reflecting surface formed of a parabolic surface, and a light source is located at a focal point of the reflecting surface or in the vicinity of the focal point. A parabolic mirror that reflects the light from the light source forward by the reflecting surface, and a parabolic mirror that is arranged to face the front of the parabolic mirror and that reflects the light from the parabolic mirror. A flat mirror having a reflecting surface for reflecting light toward the surface and having a projection opening at a portion facing the central portion of the parabolic mirror.

The illumination device according to claim 2 is the illumination device according to claim 1, wherein at least one of the reflecting surfaces of the parabolic mirror and the plane mirror transmits or absorbs a light beam in a specific light wavelength range. It is a film that is applied.

[0020]

In the illumination device according to the first aspect, the light from the light source is reflected by the parabolic mirror to form a light flux that is substantially parallel to the front,
Of the parallel light flux in the front plane mirror aperture, the light that goes to this aperture passes through this aperture as it is and reaches the illuminated object directly to illuminate, while the light that faces the reflecting surface of the plane mirror is reflected by the reflecting surface. , Is incident on the parabolic mirror as a parallel light flux, reflected toward the focal point by the reflecting surface of the parabolic surface, transmitted through this focal point, and is incident on the reflecting surface near the focal point. Almost all the light that is emitted from the light source and reflected by the parabolic mirror passes through the opening because it is again converted into a nearly parallel light flux, is reflected forward, passes through the opening, reaches the object to be illuminated, and illuminates. It will reach the illuminated object,
The light utilization efficiency is significantly improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the light emitted from the light source in a specific light wavelength range is transmitted through the coatings of the parabolic mirror and the plane mirror. Alternatively, since the light is absorbed, it is illuminated by a light beam having an arbitrary desired wavelength range adapted to the illuminated object.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the illumination device of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 11 is a parabolic mirror, and this parabolic mirror 11 has a reflecting surface of a parabolic surface, and a light source 12 is attached to the focal point 11a or in the vicinity of this focal point 11a. There is. Further, as the light source 12, for example, a halogen lamp or a metal halide lamp is used. On the other hand, 13
Is a parabolic mirror mount, and this parabolic mirror mount 13 is composed of a horizontal portion 13a and a vertical portion 13b which are bent and formed by a plate material, and the vertical portion 13b has a plate surface on which the parabolic mirror 11 is mounted. An opening 14 having a shape slightly larger than the opening is formed.
The parabolic mirror 11 is integrally attached by using a pressing tool 15 so that the opening of the parabolic mirror 11 is exposed.

Further, 17 is a plane mirror, and this plane mirror 17 is attached to a plate-like plane mirror mount 19 by a U-shaped fixture 18, and furthermore, a vertical portion 13b of the parabolic mirror mount 13 is fitted with a column 20. It is attached integrally. Further, the plate surface of the flat mirror mount 19 has an opening 14 formed in the parabolic mirror mount 13.
An opening 21 having substantially the same size as that of is provided. Therefore, the reflecting surface of the plane mirror 17, that is, the surface on the parabolic mirror 11 side is
This means that the reflecting surface of the parabolic mirror 11 is arranged in front of the light source 12 through the openings 14 and 21.

Furthermore, since at least one of the reflecting surfaces of the parabolic mirror 11 and the plane mirror 17 is coated with a film that transmits or absorbs light rays in a specific light wavelength range, among the light emitted from the light source 12, Light rays in a specific light wavelength range are transmitted or absorbed by the reflecting surfaces of the parabolic mirror 11 and the plane mirror 17, and can be illuminated by light rays in any desired light wavelength range suitable for the illuminated body 23.

Further, an opening 22 for projecting light is provided in a part of the plane mirror 17, for example, a part facing the central part of the parabolic mirror 11, and the size of the opening 22 is as shown in FIG. , Is set corresponding to the illumination target area of the illuminated body 23. Further, the shape of the opening 22 may be set corresponding to the illuminated body 23,
For example, make it circular.

Next, the operation of the above embodiment will be described.

First, most of the light from the focal point 11a of the parabolic mirror 11 or the light source 12 provided in the vicinity of the focal point 11a is reflected on the reflecting surface of the parabolic mirror 11, as shown in FIG. After being captured and reflected by the reflecting surface of the parabolic mirror 11 to become a substantially parallel light beam, it is projected forward. Of this parallel light flux, the light beam near the center of the parabolic mirror 11 directly passes through the opening 22 of the plane mirror 17 provided in the front and is projected onto the illuminated object 23 to illuminate the illuminated object 23. To do.

On the other hand, the light rays outside the aperture 22 are
The light is reflected by the reflecting surface of the plane mirror 17, is first incident on the reflecting surface of the parabolic mirror 11 as it is as a parallel light flux, and is reflected toward the focal point 11a of the reflecting surface of the parabolic mirror 11. Further, the reflected light is transmitted through the focal portion 11a, is incident again on the reflecting surface of the parabolic mirror 11, and is reflected forward as a substantially parallel light flux. In this case, the incident point of the parabolic mirror 11 when it is incident again is closer to the central portion than the incident point of the parabolic mirror 11 when it is first incident, so that the reflected light is a plane mirror located in the front. It reaches the illuminated body 23 through the opening 22 of 17 and illuminates the illuminated body 23 with direct light.

Here, since the parallel luminous flux reflected by the reflecting surface of the parabolic mirror 11 decreases in the amount of light from the central portion in the radial direction, only the direct light directly passing through the opening 22 of the plane mirror 17 is covered. When the illuminating body 23 is illuminated, the light amount in the peripheral portion is lower than that in the central portion. However, according to the above-described embodiment, as described with reference to FIG. 3, the light beam that cannot be directly passed through the opening 22 and is reflected by the plane mirror 17 is reflected by the first reflection point and the second reflection point.
Since it is reflected after passing through the reflection point and added as a parallel light flux, it is possible to correct the above-described decrease in the light amount of the peripheral portion due to only the direct light. That is, since the reflection point of the reflection surface of the parabolic mirror 11 when it is incident again is located near the outer periphery of the projection shape by the opening 22, the parallel light flux reflected here is a peripheral portion on the illuminated body 23. Therefore, it is possible to correct the decrease in the amount of light in the peripheral portion due to only the direct light, and to perform good illumination with a uniform amount of light.

A long lamp as shown in FIG. 2 is used as the light source 12, and the lamp is arranged along the optical axis to secure a light flux reflecting surface by the parabolic mirror 11 which is a concave mirror and to irradiate the surface. It is often practiced to prevent the divergence of the incident light beam to the. As such a light source 12, a lamp having two bright points 12a and 12b, such as a metal halide lamp shown in FIG. 4, is used, and one bright point 12a is made to coincide with the focal point 11a of the parabolic mirror 11. When arranged, the luminous flux emitted from the other bright point 12b has a property of weakly diverging or converging, and
Although it causes a decrease in light utilization efficiency in the above, by providing the plane mirror 17 as in the above-described embodiment, it is possible to use these weakly diverging or converging light beams, and on the illuminated body 23. The light utilization efficiency can be increased.

Further, since at least one of the reflecting surfaces of the parabolic mirror 11 and the plane mirror 17 is coated with a film that transmits or absorbs light rays in a specific light wavelength range, among the light emitted from the light source 12, Since light rays in a specific light wavelength range are transmitted or absorbed by the reflecting surfaces of the parabolic mirror 11 and the plane mirror 17, it is possible to illuminate with a light ray in any desired light wavelength range adapted to the illuminated body 23. .

The plane mirror 17 functions together with the parabolic mirror 11 to enhance the utilization efficiency of the light emitted from the light source 12, and the distance from the parabolic mirror 11 is a desired amount of light on the illuminated body 23. Appropriate arrangement and setting may be performed so that the distance can be obtained, and the distance therebetween is set relatively short as shown in FIG. Further, the condenser lens which is conventionally required is also unnecessary. As a result, the entire illuminating device can be made compact, and the focus adjusting mechanism for the condenser lens is not required, so that the illuminating device can be simply constructed.

The shape of the opening 22 is not limited to the circular shape shown in FIG. 1, and may be a quadrangle as shown in FIG. 5 when the illuminated object 23 is a liquid crystal display device. The other parts of the lighting device shown in FIG. 5 are similar to those of the lighting device shown in FIG.

In the embodiment shown in FIG. 5, since the opening 22 of the plane mirror 17 has the same shape as that of the illuminated body 23, the light utilization efficiency is prevented from lowering due to the difference in the shape and a high light utilization efficiency is obtained. You can For example, when the illuminated body 23 is a liquid crystal display device and has a rectangular shape, the opening 22 of the plane mirror 17 is
If it is circular as shown in FIG. 1, a light flux that deviates from the outer edge of the illuminated body 23 to the outside occurs, and the light utilization efficiency decreases. However, as shown in FIG. 4, if the opening 22 is also the same quadrangle as the illuminated body 23, all the luminous flux is irradiated onto the illuminated body,
The light utilization efficiency is improved.

[0036]

According to the illuminating device of the present invention, the light from the light source is transmitted by the parabolic mirror through the opening of the plane mirror to reach the object to be illuminated directly for illumination, and at the same time, is directed to the reflecting surface of the plane mirror. The light is reflected by the reflecting surface and again reflected by the parabolic mirror in the forward direction as a substantially parallel light beam, passes through the opening, reaches the illuminated object, and illuminates. Therefore, the light passes through the opening and reaches the illuminated object. Therefore, the light utilization efficiency can be significantly improved, and the luminous flux emitted from the light source can be effectively utilized.
The device can be downsized and simplified, for example, a condenser lens is not required.

According to the illuminating device of claim 2, in addition to the illuminating device of claim 1, among the light emitted from the light source, light rays in a specific light wavelength range are formed by the coatings of the parabolic mirror and the plane mirror. Since the light is transmitted or absorbed, it can be illuminated with a light beam having any desired light wavelength range adapted to the object to be illuminated.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a lighting device of the present invention.

FIG. 2 is a cross-sectional view showing the same lighting device.

FIG. 3 is a schematic configuration diagram showing an optical path of the above illumination device.

FIG. 4 is an explanatory diagram showing a state in which a lamp having two bright points is used as a light source.

FIG. 5 is an exploded perspective view showing another embodiment of the same.

FIG. 6 is a schematic configuration diagram showing a conventional illumination device.

FIG. 7 is a schematic configuration diagram showing another conventional lighting device.

FIG. 8 is a schematic configuration diagram showing another conventional lighting device.

FIG. 9 is a schematic configuration diagram showing still another conventional lighting device.

[Explanation of symbols]

 11 Parabolic mirror 11a Focal part 12 Light source 17 Plane mirror 22 Aperture

Claims (2)

[Claims] 1. A parabolic reflecting surface, wherein a light source is positioned at a focal point of the reflecting surface or in the vicinity of the focal point, and the light from the light source is directed forward by the reflecting surface. A parabolic mirror for reflecting the light, a parabolic mirror facing the front of the parabolic mirror, and a reflecting surface for reflecting the light from the parabolic mirror toward the reflecting surface of the parabolic mirror. An illumination device, comprising: a parabolic mirror; and a plane mirror provided with an opening for projecting light in a portion facing a central portion of the parabolic mirror. 2. The illumination according to claim 1, wherein at least one of the reflecting surfaces of the parabolic mirror and the plane mirror is provided with a coating that transmits or absorbs a light ray in a specific light wavelength range. apparatus.