1. Field of the Invention
The present invention relates to an illumination source device and a projection image display device with the illumination source device.
2. Description of Related Art
There have been known various kinds of projection image display apparatuses for displaying an image onto a screen such as a projector in which LCD panels, of a transparent or a reflective type, or DMD (Digial Micro-mirror Device) panels are used to modulate light for projecting an LED display image or an image provided by a DMD. Such a projection image display apparatus is equipped with an illumination source device. It is known to be preferred to use an illumination source device that provides a high intensity light beam for illumination and a uniform luminance distribution to an LCD panel. Conventionally, it has been popular to employ high intensity discharge lamps including an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp and the like as a light source. However, the illumination source device using a high intensity discharge lamp is oversized, while being capable of providing a high intensity illumination light beam.
In light of the drawbacks of the conventional projection image display apparatuses, it has been proposed to use a light emitting diode (LED), that is small in size and light in weight, for the illumination source device. However, it has come to light that the LED produces a considerable amount of heat when using it with a practical luminance. The LED encounters deterioration in property and diminution in useful life span when the LED producing heat in excess.
In order to solve this problem existing with the LED, there has been proposed an illumination source device in which a mounting base board having a draft bore or draft bores is used to mount a plurality of LED elements thereon so as to enhance the heat releasing efficiency of the illumination source device. For a more complete description of this problem and a proposed solution, see Unexamined Japanese Patent Publication No. 2004-95655, issued Mar. 25, 2004.
It is therefore an object of the present invention to provide an illumination source device using an LED element as a light source which is simple and compact in structure and capable of cooling the LED element.
It is another object of the present invention to provide a projection image display device accompanied by the illumination source device using an LED element.
According to one aspect of the present invention, the illumination source device comprises an LED element for emitting a light beam for illumination, a mounting base board having a heat conductivity higher than 50 W/m·K for mounting the LED element thereon, and a metal supporting structure for supporting the mounting base board. The metal supporting structure has an axial bore formed therein through which the light beam for illumination passes and which has an axial line perpendicular to the mounting base board or is made in the form of a hollow body. The hollow metal supporting structure may be provided with fins extending exterior side walls thereof for releasing heat building up within the axial bore.
It is preferred for the illumination source device to comprise a collimator lens mounted in the axial bore for collimating a light beam emitted from the LED element. It is further preferred for the illumination source device from a practical standpoint to be accompanied by an air blower that is disposed closely behind the illumination source device so as to produce and direct airflows against the mounting base board and around the metal supporting structure.
The illumination source device comprising the mounting base board having a heat conductivity higher than 50 W/m·K on which an LED element is mounted thereon and the metal supporting structure which supports the mounting base board transfers heat produced by the LED element to both the mounting base board and the metal supporting structure and then releases it into the air. As a result, the LED is effectively cooled, thereby being prevented from being overheated to a higher temperature, and hence, from encountering not only deterioration in optical property but also diminution in useful life span. Furthermore, because the metal supporting structure has an axial bore through which the light beam for illumination passes and is provided with a collimator lens mounted in the axial bore for collimating the light beam emitted from the LED element, the illumination source device provides an effectively collimated light beam for illumination.
According to another aspect of the present invention, the projection image display device for displaying images on a screen is accompanied by the illumination source device for projecting an LED display image on the screen. This projection image display device is compact in structure by virtue of the compactness of the illumination source device.
The foregoing and other objects and features of the present invention will be clearly understood from the following detailed description when reading with reference to the accompanying drawings, wherein the same reference signs have been used to denote same or similar parts throughout the drawings, and in which:
Referring to the accompanying drawings in detail, and, in particular, to
The illumination source device 3 includes a light source unit 18, an integrator made up of lenses 19 and 20, and a polarization direction controlling element 21. The light source unit 18, which will be described in detail later, emits a white light beam for illumination containing red (R), green (G) and blue (B) components of light forward. The integrator lenses 19 and 20 are disposed in front of the light source unit 18 to uniformize the white light beam from the light source unit 18. The polarization direction controlling element 21 is disposed on one side of the integrator lenses 19 and 20 opposite to the light source unit 18 to change polarization directions of the white light beams passing through the integrator lenses 19 and 20. There is provided an air blower 43 closely behind the light source unit 18 for cooling the light source unit 18.
The while light beam coming out of the illumination source device 3 enters the liquid crystal projector 2. Specifically, the collimated and polarized white light beam for illumination is reflected at a right angle by the reflecting minor 4 and further reflected at a right angle by the reflecting mirror 5, and then directed to the dichroic mirror 9. The white light beam incident upon the dichroic mirror 9 partly transmits through and is partly reflected at a right angle by the dichroic mirror 9. That is, a red component of the light beam transmits through the dichroic mirror 9 and directed toward the reflecting mirror 6. The red light beam incident upon the reflecting mirror 6 is reflected at a right angle by the reflecting mirror 6 to illuminate the LCD panel 12R. At the same time, the remaining components, namely green and blue, of the light beam are reflected at a right angle by the dichroic mirror 9 and directed toward the dichroic mirror 10. The light beam incident upon the dichroic mirror 10 partly transmits through and is partly reflected at a right angle by the dichroic mirror 10. That is, the blue light beam transmits through the dichroic mirror 10 and is directed toward the reflecting mirror 7. At the same time, the remaining constituent, namely the green light, of the light beam is reflected at a right angle by the dichroic mirror 10 to illuminate the LCD panel 12G. The blue light beam incident upon the reflecting mirror 7 is reflected at a light angle by the reflecting mirror 7 and subsequently reflected at a right angle by the reflecting mirror 8 to illuminate the LCD panel 12B. The red, green and blue components of light entering and exiting from the LCD panels 12R, 12G and 12B, respectively are integrated together by the dichroic prism assembly 13 to provide a color image for projection on the screen 15 by the projection lens system 14.
Referring to
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In the operation, when the liquid crystal projector 2 is powered on to activate the light source unit 18, the LED chip 29 is excited to emit white light. The white light is collected by the protective cap 32 and enters and exiting as a collimated white light beam from the collimator lens 27. The collimated white light beam enters and exits from the integrator lenses 19 and 20 and then enters the polarization direction controlling element 21. The white light beam coming out of the illumination source device 3 that is uniformized in polarization direction is directed as illumination light toward the LCD projection system 2. The white light beam incoming the LCD projection system 2 is split into three light beams of red, green and blue components by the dichroic mirrors 9 and 10. The light beams of red, green and blue components are modulated by the LCD panels 12R, 12G and 12B, respectively, in accordance with image data provided by a video signal. The light beams of red, green and blue components are then recombined by the dichroic prism assembly 13 and projected as a color image onto the screen 15 by the projection lens 14.
When having a long run of the LCD projector 2, the LED chip 29 is accompanied by heat. However, according to the light source unit 3, the heat radiated from the LED chip 29 is transferred to the mounting base board 26 through the heat transfer member 33 and then partly released into the air from the mounting base board 26. Concurrently, the heat transferred to the mounting base board 26 is partly transferred to and released into the air from the housing 28. In this way, the LED chip 29 is well cooled. In particular, the air blower 43 provided closely behind the light source unit 18 facilitates release of a large amount of heat for efficient cooling of the LED chip 29. Consequentially, the LED chip 29 is prevented from deteriorating in property and encountering diminution in useful life span. Furthermore, because the light source unit 18 is simple and compact in structure, it is ensured to provide a compact design for the illumination source device 3, and hence the LCD projector 2.
Although, in the above embodiment, the LED unit 25 has an integral structure in which the LED chip 29, the leading electrodes 30 and 31, the heat transfer member 33 and the bell-shaped protective cap 32 are preassembled as one whole unit, a similar structure can be taken in a case where the LED chip 29 is mounted directly mounted on the mounting base board 26 with the same effect as described above.
In alternative embodiments, a plurality of white light LEDs or different colors of LEDs may be employed in place of the single white light LED unit 25, and, in this instnce, these LEDs can be densely-mounted on the mounting base board 26 of the light source unit 18. The housing 28 may be in any desired shape in place of rectangular as long as it is suitable for suitable for supporting the mounting base board 26 thereon.
The LCD panels 12R, 12G and 12B operative to modulate the light beams of red, green and blue components, respectively, may be of a reflective type LCD panels or replaced with DMDs. Further, the light source unit 18 may be used in combination with projectors of a type other than a projection type and equipments that need illumination.
It is to be understood that although the present invention has been described with regard to preferred embodiments thereof various other embodiments and variants may occur to those skilled in the art, which are within the scope and spirit of the invention, and such other embodiments and variants are intended to be covered by the following claims.
Number | Date | Country | Kind |
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2005-065370 | Mar 2005 | JP | national |