JPH064753U - LCD projector lighting device - Google Patents

Abstract

(57) [Abstract] [Purpose] The reflected rays reflected by the second parabolic reflector are reflected again by the first parabolic reflector to reduce the ineffective rays during illumination and improve the illumination efficiency. It is a thing. [Configuration] The first and paraboloidal reflectors 1 facing conjugated focus f, a second discharge of having a focal length p ₁ is larger than the focal length p ₂ of the first parabolic reflector 1 The parabolic reflector 3 is provided, and an opening is formed on the axis of the second parabolic reflector.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a lighting device for a liquid crystal projector, and more particularly to a lighting device for a liquid crystal projector suitable for improving the efficiency of utilization of light emitted from a light source.

[0002]

[Prior art]

 Conventionally, many illumination devices for liquid crystal projectors have been provided as shown in the sectional view of FIG. In the figure, reference numeral 1 is a parabolic reflector that reflects light emitted from a light source, and a light source 2 composed of a lamp or the like is arranged at a focus position f of the parabolic reflector 1. Reference numeral 4 denotes a condenser lens on which the emitted light from the light source 2 and the reflected light from the parabolic reflector 1 are incident, and the light incident on the condenser lens 4 is condensed and passed through the liquid crystal 5 to the projection lens 6. It is incident.

In the illuminating device of the liquid crystal projector configured as described above, the radiated light from the light source 2, for example, radiated light a is reflected by the parabolic reflector 1 and becomes parallel light a and is reflected by the condenser lens 4. Incident. The parallel light a is refracted by the condenser lens 4 and is condensed so as to enter the entrance pupil of the projection lens 6. At this time, the condenser lens 4 has a size that illuminates the image of the liquid crystal 5 without vignetting, and the parallel light incident on the condenser lens 4 is used as an illuminating light beam of the liquid crystal 5.

[0004]

[Problems to be solved by the device]

 However, in the above-described conventional liquid crystal projector illumination device, the range of the parallel radiated light a reflected from the light source 2 by the parabolic reflector 1 is used as an effective ray for illuminating the liquid crystal projector. The emitted light in the range of emitted light b to emitted light c has a drawback that it does not contribute to illumination and becomes an ineffective ray.

The present invention has been made in view of the above points, and an object thereof is to solve the drawbacks of the conventional example and to provide a second parabolic reflector facing the conventional parabolic reflector. By arranging the above, it is possible to effectively use the ineffective light rays as the illumination light, and to provide the illumination device of the liquid crystal projector with improved illumination efficiency.

[0006]

[Means for Solving the Problems]

 The illuminating device of the liquid crystal projector of this invention has a light source provided at the focal point of a parabolic reflector, and the emitted light from this light source is reflected by the parabolic reflector to become parallel light and enters a condenser lens. In the configured illumination device of the liquid crystal projector, the second parabolic reflector having the focal length larger than the focal length of the parabolic reflector facing the position where the focal point is conjugated with the parabolic reflector is the same. It is provided on the optical axis, and an opening is formed on the axis of this second parabolic reflector.

[0007]

[Action]

 According to this invention, a second parabolic reflector having a focal point formed at a position conjugate with the focal point of the first parabolic reflector is provided, and the second parabolic reflector is provided with the first parabolic reflector. On the same optical axis with the second parabolic reflector having a focal length greater than that of the first parabolic reflector. It was formed by arranging so that

In addition, an opening is provided on the axis of the second parabolic reflector through which the light incident on the condenser lens passes, and the lamp is formed at the conjugate focus of the first and second parabolic reflectors. The light emitted from the light source is reflected by the first and second parabolic reflectors to become parallel radiation and is incident on the condenser lens.

As described above, the reflected light beam reflected by the first parabolic reflector enters the condenser lens through the opening, and the reflected light beam reflected by the second parabolic reflector is further reflected by the second parabolic reflector. It can be reflected again by the parabolic reflector of No. 1 and transmitted through the above-mentioned opening to be incident on the condenser lens. The radiated light which was the ineffective ray until now is reflected by the second parabolic reflector. And it becomes a parallel light of the effective ray.

That is, by providing the second parabolic reflector, it is possible to increase the amount of effective light rays from the light source and improve the illumination efficiency of the liquid crystal projector.

[0011]

【Example】

 An embodiment of a lighting device of a liquid crystal projector according to the present invention will be described with reference to FIGS. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted. 1 is a principle view for explaining the operation of the present invention, FIG. 2 is a sectional view showing an embodiment of the present invention, FIG. 2 (A) is a side sectional view, and FIG. 2 (B) is an opening side. It is the front view seen from.

In the figure, reference numeral 3 denotes a second parabolic reflector, and the second parabolic reflector 3 has an opening 3a formed therein. FIG. 1 illustrates the operation of the radiated light from the origin of the parabola of the first parabolic reflector 1 by calibrating the x-axis and the y-axis, where the x-axis is the radiated light from the light source 2. Forms the optical axis of.

The focal point of the first parabolic reflector 1 and the focal point of the second parabolic reflector 3 form a substantially same focal point f on the same optical axis and are conjugated with each other, and the second parabolic reflector is formed. The parabolic reflector 3 is installed opposite to the first parabolic reflector 1 as shown in the figure, and the second parabolic reflector 3 is illuminated with the image size of the liquid crystal without vignetting. An opening 3a having a size is provided, and the focal length p ₂ of the _second parabolic reflector 3 is larger than the focal length p ₁ of the first parabolic reflector 1 (p ₁ <P ₂ ).

The liquid crystal projector illumination device configured as described above is reflected by the first parabolic reflector 1 from the light source 2 installed at the focal point f of the first and second parabolic reflectors 1 and 3. The emitted light, for example, the emitted light a in the figure becomes a parallel light beam, passes through the opening 3a of the second parabolic reflector 3 and enters the condenser lens 4. Further, the emitted light between the emitted light b and the emitted light c from the light source 2 does not enter the condenser lens 4 and is emitted as an ineffective light ray.

On the other hand, the radiated light a ₁ reflected by the second parabolic reflector 3 from the light source 2 becomes parallel radiated light a ₂ and enters the first parabolic reflector 1 to be reflected by the first parabolic reflector 1. The reflected radiant light a ₃ reflected again by the parabolic reflector 1 passes through the focal point f, is reflected again by the reflecting surface on the opposite side of the first parabolic reflector 1, and becomes a parallel reflected radiated light a ₄ . Then, the light can pass through the opening 3a and enter the condenser lens 4.

In this way, the radiated light a ₁ which is an ineffective ray in the conventional lighting device without the second parabolic reflector 3 is reflected by the second parabolic reflector 3 to become an effective ray. It can be used to illuminate LCD projectors. The limit level of synchrotron radiation a ₁ that can be used as this effective ray is as follows.

The parabolic curve of the first parabolic reflector 1 is represented by “y ² = 4p ₁ x”, and “y = ± 2p ₁ ” at “x = p ₁ ”, as shown in FIG. Becomes That is, “y = ± 2p ₁ ” on the y-axis represents the light ray height at which the radiated light emitted from the light source 2 is reflected by the first parabolic reflector 1 to be an effective light ray, and “y = Parallel light reflected by the first parabolic reflector 1 having a height of ± 2p ₁ ”or more and reflected after passing through the focal point f, is reflected again on the opposite side of the first parabolic reflector 1. Then, it becomes a parallel ray having a low ray height of “y = ± 2p ₁ ” or less, which can be transmitted through the opening 3a and incident on the condenser lens 4.

Further, the contact point of the paraboloid where the first parabolic reflector 1 and the second parabolic reflector 3 are coupled is as follows. The parabolic curve of the second parabolic reflector 3 is represented by "y ² = -4p ₂ {x- (p ₁ + p ₂ )}", and the parabolic curve of the first parabolic reflector 1 is described. Eliminating "y" from the curve "y ² = 4p ₁ x" yields "x = p ₂ ", and in this "x = p ₂ ", "y" is "y ² = 4p ₁ p ₂ " Becomes That is, the two first and second parabolic reflectors 1 and 3 are joined at the coordinate position determined by the focal lengths p ₁ and p ₂ of “y ² = 4p ₁ p ₂ ”, and the radiation of this ray height is obtained. Even the light is reflected by the second parabolic reflector 3 and becomes effective as an illumination light beam of the liquid crystal projector.

Naturally, the emitted light from the light source 2 directly reflected by the first parabolic reflector 1 also passes through the opening 3a of the second parabolic reflector 3 as in the conventional case, and then the condenser lens 4 is formed. Is used as an effective ray of illumination for the liquid crystal projector. In this way, by utilizing the reflection at the second parabolic reflector 3, the emitted light from the light source 2 is repeatedly reflected at the first and second parabolic reflectors 1 and 3 to cause the liquid crystal projector. The ineffective ray can be converted into an effective ray as the illumination ray of.

The reflecting surfaces of the first and second parabolic reflectors 1 and 3 of the sectional view shown in FIG. 2 (A) are formed by parabolic mirrors, and heat generation of the light source 2 such as a lamp is taken into consideration. In general, cold-mirror processing is performed, so the infrared band component of the reflected light that is reflected by this parabolic mirror is emitted in the direction opposite to the optical axis, and the reflected parallel rays do not include infrared rays and waste heat treatment is performed. Can reduce defects caused by heat generation.

FIG. 2B shows the opening 3a of the second parabolic reflector 3 formed with an aspect ratio of 4: 3, and the opening 3a has the aspect ratio of the first and the second. If the height of the reflected parallel rays of the parabolic reflectors 1 and 3 is lower than the above-mentioned "y = ± 2p ₁ ", it is possible to perform the shading process of the invalid illumination rays.The opening 3a is formed in consideration of this shading amount. To be done. Moreover, the opening 3a may be formed in a rectangular shape having another aspect ratio or a circular shape.

Further, since the light source 2 is not a perfect point light source, the light source 2 is installed before and after the focal point including the focal point f of the first parabolic reflector 1 to cause uneven illumination. It can be reduced. Furthermore, by selecting the parabolic curved surface of the second parabolic reflector 3, it is possible to compensate for the reduction of the peripheral light amount of the projection lens 6 due to the "COS4 power law".

[0023]

[Effect of device]

 Since the illuminating device of the liquid crystal projector according to the present invention is provided with the second parabolic reflector 3 as described above, the radiated light from the light source 2 which has not conventionally contributed to the illumination is emitted by the second parabolic reflector. By being reflected by the surface reflector 3 and incident on the first parabolic reflector 1, there is an effect that the effective light rays of the illumination of the liquid crystal projector can be increased and the illumination efficiency can be improved.

Further, by changing the second parabolic reflector 3 from the cold mirror to the full mirror, the reflected light beam totally reflected by the second parabolic reflector 3 becomes the first parabolic reflector. There is also an effect that infrared rays are emitted in the direction opposite to the optical axis when re-reflecting at 1, and waste heat treatment for heat generation due to radiated light from the light source 2 can be performed.

Further, since the ineffective ray can be shielded by the opening 3a of the second parabolic reflector 3, it is possible to easily process the stray light of the illumination of the liquid crystal projector by the ineffective ray.

Moreover, it has excellent features such as a simple structure and easy implementation because it can be constructed at low cost.

[Brief description of drawings]

FIG. 1 is a principle diagram illustrating a path operation of emitted light of a lighting device of a liquid crystal projector according to the present invention.

FIG. 2 shows an embodiment of the present invention.
(A) is a side sectional view and FIG. 2 (B) is a front view seen from the opening.

FIG. 3 is a configuration diagram showing a conventional example.

[Explanation of symbols]

1 First Parabolic Reflector 2 Light Source 3 Second Parabolic Reflector 4 Condenser Lens 5 Liquid Crystal Member 6 Projection Lens f Focus p ₁ Focal Length of First Parabolic Reflector p ₂ Second Parabolic Reflector Focal length of object reflector

Claims (1)

[Scope of utility model registration request] 1. A light source provided at the focal point of a parabolic reflector, and a liquid crystal configured such that the emitted light from this light source is reflected by the parabolic reflector to become parallel emitted light and enters a condenser lens. In a lighting device of a projector, a second focal point which is opposite to a position where a focal point is conjugated with the parabolic reflector and has a focal length larger than a focal length of the parabolic reflector
An illumination device for a liquid crystal projector, wherein the parabolic reflector is provided on the same optical axis, and an opening is formed on the axis of the second parabolic reflector.