Light-source device and projection type display device

#1. Field of the Invention

#The present invention relates to a light-source device for illuminating a light valve means, such as DMD, used in a projection type display device.

#2. Description of the Related Art

#The invention will become more readily appreciated and understood from the following detailed description of embodiments of the invention when taken in conjunction with the accompanying drawings, in which:

#FIG. 1 is a diagram showing the construction of a light-source device according to Embodiment 1;

#FIG. 2 is an explanatory drawing for the purpose of explaining the functions of a rod integrator;

#Embodiment 1

#FIG. 1 is a diagram showing the construction of a light-source device according to one embodiment of the invention. The white luminous flux emitted from a lamp 10 is reflected by an elliptical mirror 11, and is converted into an approximately parallel luminous flux L1. The luminous flux L2 that pass thorough the condenser lens 12 enters color filter 15. The color filter 15 converts the white luminous flux L2 into R G B color light. The luminous flux L2 enters into the rod integrator 3 from an injection end 3a disposed in the vicinity of the convergence point of the luminous flux L2. The rod integrator 3 is a rectangular pillar optical element formed from a glass or plastic material. The luminous flux L2 that enters into the rod integrator 3 reaches an emitting end 3b, being reflected at the inner side surfaces. A luminous flux L3 emitted from the emitting end 3b enters into a condenser lens 4. A luminous flux L4 hat passes through the second condenser lens 4 enters to the diaphragm 5. The diaphragm 5 blocks a part of the luminous flux L4. The luminous flux L4 that passes through an aperture 5t of the diaphragm 5 is reflected in the direction of an optical axis X1 by a mirror 7. The luminous flux L5 reflected by the mirror 7 forms a rectangular image on a plane S, where a light valve means such as a DMD is disposed. The shape of the image formed on the plane S is analogous to the emitting end 3b. A plane S′ indicates an image formed by the luminous flux L4 that passes through the aperture 5t, when the mirror 7 was not placed. The image on the plane S′ has conjugate relationship with the image formed on the plane S.

#FIG. 2 is an explanatory drawing for the purpose of explaining the functions of the rod integrator 3. In FIG. 2, the rod integrator 3 has a refractive index of n, a length of L, and cross-sectional height of H. P indicates the convergence point of the luminous flux. The luminous flux that enters into the rod integrator 3 from the injection end 3a reaches the emitting end 3b either being reflected by a predetermined number of times at the inner side surfaces of the rod integrator 3 or without reflection. The luminous flux that is totally reflected from the inner side surfaces illuminates the emitting end 3b, like light rays emitted from imaginary light-source points P0′, P1′ and P2′ formed on a plane L/n distant from the emitting end 3b of the rod integrator 3. Since the emitting end 3b receives total illumination flux emitted by imaginary light-source point, there is good uniformity of illumination within the emitting end 3b. As shown in FIG. 2, the heights of the imaginary light-source points P0′, P1′ and P2′ are given by 1/2H, 3/2H and 5/2H, which increase by a multiple of H (the cross-sectional height of the rod integrator 3) according to the number of the times of reflections.