JPH04104241A - Illuminating light source device - Google Patents

Abstract

PURPOSE:To improve the quality of an image on a screen by making a radiated luminous flux emitted from a light source for emitting light almost collimated beam of light or providing an aspherical confocal lens system between a body to be illuminated and the light source when a limited range is illuminated. CONSTITUTION:The luminous flux radiated from the light source 1 is reflected by a parabolic reflection mirror 2 and emitted nearly in parallel with an optical axis. Then, the light is consecutively controlled by an aspherical lens 3 at a 1st stage so that the center part thereof may be scattered to a circumference with the effect of a convex lens of a high degree and the peripheral part may not be scattered so much. Thereafter, the light intensity distribution on a surface which should be illuminated is made uniform by an aspherical convex lens 4 of a degree nearly as high as the center part of the lens at the post stage so that the light may become the collimated beam of light in accordance with the bend of respective light beams, and all the areas are illuminated by the collimated beam of light. Thus, the illuminance of a video projected to the screen through a projecting lens is made equally uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] This invention relates to bright light source devices such as projection display devices (liquid crystal projectors) and overhead projectors.

[Prior Art] A light source device of a conventional projection type display device uses a parabolic reflector to create a substantially parallel light beam as shown in FIGS. 5 and 7, or a light source device as shown in FIG. By placing a spherical reflector on the back and a condenser lens on the front,
It had a structure that emitted approximately parallel light forward.

[Problems to be Solved by the Invention] However, in the conventional example described above, the light intensity distribution of the illumination light of the light source device itself is not uniform, and the illuminance of the peripheral area is lower than that of the central area, and the illuminance on the screen is low. There was a problem with uneven brightness. This has the problem that even if the light is ideally emitted from a single light source, when it is made into a group of parallel rays by a parabolic reflector or a condenser lens, the center is brighter and the illuminance decreases toward the periphery. Was. As another example, when a discharge lamp such as a metal halide is emitted in parallel using a parabolic reflector, a ring-shaped bright part appears as shown in Fig. 7, and a dark part called a hollow part appears in the center. There was also the problem of low illuminance in the surrounding area. SUMMARY OF THE INVENTION The present invention aims to solve these problems and to make the illuminance of the illuminated area or the image projected onto the screen through the projection lens uniform.

[Means for Solving the Problems 1] The illumination light source of the present invention converts the emitted light beam emitted from a light emitting light source such as a lamp into substantially parallel light using a reflecting mirror or a condenser lens, or when illuminating a limited range, It is characterized by having an aspherical confocal lens system between the object to be illuminated and the light source.

[Embodiment] FIG. 1 is a central cross-sectional view of an embodiment of the present invention, in which a light beam emitted from a light source 1 is reflected by a parabolic reflector 2 and emitted substantially parallel to the optical axis.

If this continues, the light intensity distribution will be such that the center of the optical axis is brighter and the closer to the periphery it is darker, as shown in FIG.

Therefore, the first stage aspherical lens 3 continuously controls the light so that the central part is affected by a strong concave lens effect to the surroundings, and the peripheral part is not scattered too much. A strong aspherical convex lens 4 at the center of the rear stage is used to provide a uniform light intensity distribution to the surface to be illuminated and illuminate the entire area with a parallel beam of light so that it becomes parallel light according to the degree of bending of the incident light ray. be able to.

FIG. 2 is a main cross section of another embodiment of the present invention, in which the light W
! The light emitted from A21 is turned into substantially parallel light by the condenser lens 27, and as in the case of FIG. Can illuminate non-illuminated objects such as liquid crystals and slide films.

The light intensity distribution without the above three aspherical confocal lens systems is quantitatively slightly different, but qualitatively, the center of the same tendency is bright, so the aspherical confocal lens system Although the curved surface is slightly different, the function is the same. Next, FIG. 3 is a main sectional view of an embodiment of the present invention in which the condenser lens in FIG. 2 and the aspherical lens in the preceding stage are integrated, and the function is the same as that of the embodiment in FIG. 2. At this time, by integrating the lens, the number of parts is reduced, the weight is reduced, and costs are reduced. Furthermore, it is also possible to integrate an aspherical confocal lens system and make both end surfaces of the glass rod aspherical lenses.

FIG. 4 is a main cross section of another embodiment of the present invention, and when a metal halide lamp or the like is used as the light source, and when the aspherical confocal lens system 33, 34 is not used, as shown in FIG. A bright ring-shaped brightness unevenness occurs. At this time, the aspherical lens in the front stage scatters the bright areas with a convex lens effect, and the dark areas in the center and periphery are made up of smooth curved surfaces, making the surface of the target object uniform. With the aspherical lens in the latter stage,
- By converting the uniform light into a parallel beam,
Moreover, a parallel illumination light beam can be obtained.

[Effects of the Invention] As described above, according to the present invention, the emitted light beam emitted from a light emitting light source such as a lamp is converted into substantially parallel light using a reflecting mirror or a condenser lens, or a limited area is illuminated. In this case, by providing an aspherical confocal lens system between the object to be illuminated and the light source, the object to be illuminated can be illuminated with uniform illuminance and parallel light. This has the effect of preventing, for example, uneven transmittance due to the viewing angle dependence of the liquid crystal light valve and a decrease in contrast for each part, and providing high image quality similar to that on a screen.

[Brief explanation of the drawing]

FIG. 1 shows an illustration of the illumination light source device of the present invention. FIG. 11 is a main sectional view showing an example in which No. 11 mirrors are used. FIG. 2 is a main sectional view showing an embodiment of the illumination light source device of the present invention using a spherical reflecting mirror and a condenser lens. FIG. 3 is a main sectional view showing an embodiment of the illumination light source device of the present invention in which a condenser lens and a front-stage aspheric lens are integrated. FIG. 4 is a main sectional view showing an embodiment in which a discharge lamp is used as the lamp of the illumination light source device of the present invention. FIG. 5, FIG. 6, and FIG. 7 are main sectional views showing a conventional illumination light source device. 1, 21, 31. 41, 51. 61, 71・
・・Light source lamp 2.42.52.72 ・・Parabola reflector 3.23.4
3...Front stage aspherical lens 4.24.34.44.
・Rear stage aspheric lens 5.25.35.45.55.65
．． 75...Illuminance distribution 26.36.66...Back spherical reflector 27...
・・・・・・Condenser lens 37・・・・・・・・・
...Applicant for aspherical condenser lenses and above Seiko Epson Corporation

Claims (1)

[Claims] The radiant beam emitted from a light emitting light source such as a lamp is converted into approximately parallel light using a reflecting mirror or a condenser lens, or when illuminating a limited area, an aspherical confocal lens system is placed between the illuminated object and the light source. An illumination light source device comprising: