Patent Application
20170052434
The present invention relates to a cooling structure of an illumination optical system that uses fluorescent material and to a projection display apparatus.
In recent years, illumination optical systems have been proposed that are equipped with fluorescent material that emits fluorescent light in response to the irradiation of excitation light. This type of illumination optical system is used in, for example, a projection display apparatus.
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The system disclosed in Patent Document 1 is one example of an illumination optical system that is provided with this type of fluorescent wheel. In Patent Document 1, an illumination optical system is disclosed that is provided with a fluorescent unit that has a fluorescent wheel and a motor that rotates the fluorescent wheel.
The fluorescent wheel disclosed in Patent Document 1 has a substrate that is provided to freely rotate around a rotational axis that is orthogonal to one surface. A fluorescent region and a reflective region are formed on one surface of the substrate. The fluorescent region has a fluorescent layer that produces fluorescent light of a predetermined wavelength in response to irradiation of laser light. The reflective region is a region that reflects laser light. The laser light that is irradiated upon the fluorescent wheel is repeatedly irradiated upon the fluorescent region and the reflective region of the rotating fluorescent wheel, whereby the fluorescent light that is emitted from the fluorescent material and the laser light that is reflected by the reflective region are successively emitted from the fluorescent wheel.
The illuminance of the light that is emitted from this illumination optical system depends on the quantity of fluorescent light that is generated from the fluorescent material. The fluorescent material produces heat as it undergoes laser light irradiation and has a property by which the light-emission efficiency is decreased by the production of heat. Accordingly, heat that is generated from the fluorescent material must be controlled to prevent any decrease of the illuminance of light produced from the illumination optical system.
A construction is disclosed in Patent Document 2 that has a fluorescent wheel on which depressions are formed in the fluorescent layer and a fan that blows cooling air toward the depressions of the fluorescent wheel. In the construction disclosed in Patent Document 2, turbulence is produced by blowing the cooling air upon the depressions of the fluorescent wheel and an improvement in the cooling efficiency of the fluorescent material is due to the effect of heat diffusion.
In the illumination optical system described in Patent Document 1 described above, the fluorescent material is cooled by the flow of air surrounding the fluorescent wheel that the fluorescent wheel itself receives when the fluorescent wheel is rotating. As a result, the cooling effect of cooling the fluorescent material is rather poor in the illumination optical system described in Patent Document 1.
In the construction disclosed in Patent Document 2, cooling air is blown locally toward the laser light irradiation portion of the fluorescent layer of the fluorescent wheel. In this construction described in Patent Document 2, the effect of cooling the fluorescent material is still inadequate, and a further increase of the cooling efficiency is to be desired.
In Patent Document 3, a construction is disclosed in which a fan is arranged in the vicinity of the fluorescent wheel that causes cooling air to flow toward the surface on the side on which the fluorescent layer is formed. However, in an illumination optical system that uses a fluorescent wheel, a condensing lens for condensing the fluorescent light that is emitted from the fluorescent layer is arranged adjacent to the fluorescent layer. As a result, the cooling air blows against the lens holder that supports the condensing lens and thus obstructs the flow of cooling air, whereby the flow of a sufficient amount of cooling air on the surface of the fluorescent wheel becomes problematic. The problem arises in the construction described in Patent Document 3 that in which cooling air is thus guided only to one side of the surface of the fluorescent wheel and the flow of the cooling air is obstructed by the lens holder, and the cooling efficiency of the fluorescent material is therefore low.
In addition, as shown in
Accordingly, the low cooling efficiency of the fluorescent material in the illumination optical system described above that is related to the present invention results in a tendency for the temperature of the fluorescent material to increase, with the result that the illuminance of light emitted from the illumination optical system decreases. The problem consequently arises in which maintaining decreases in line with increases in the continued use of the illumination optical system.
It is therefore an object of the present invention to provide a structure for cooling an illumination optical system and a projection display apparatus that allow an increase in the cooling efficiency of the fluorescent material and thus prevent a decrease in the illuminance of light emitted from the illumination optical system.
To achieve the above-described object, the structure for cooling an illumination optical system according to the present invention is provided with a fluorescent unit having a fluorescent layer that emits fluorescent light in response to excitation light that is irradiated from a light source, a fan that supplies cooling air to the fluorescent unit, and a duct that partitions the internal space and the external space in which the fluorescent units is arranged and that guides cooling air supplied from the fan to the fluorescent unit.
In addition, the projection display apparatus according to the present invention is provided with an illumination optical system that includes the above-described cooling structure for an illumination optical system and an image generation optical system that includes an image element that modulates light emitted from the illumination optical system in conjunction with an image signal.
The present invention enables an increase in the efficiency of cooling a fluorescent material and can thus prevent a decrease in the illuminance of light that is emitted from an illumination optical system.
Actual exemplary embodiments of the present invention are next described with reference to the accompanying drawings.
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Fluorescent wheel 12 of the present exemplary embodiment is configured to emit only yellow light, but fluorescent wheel 12 is not limited to this form. As fluorescent wheel 12, a fluorescent layer may be partitioned to emit fluorescent light of a different color according to the irradiation position of the laser light on the fluorescent layer.
Through the use of fluorescent wheel 12, the irradiation position of laser light changes with the rotation of fluorescent wheel 12, whereby any imbalance in the temperature of the fluorescent material in each portion of fluorescent layer 12b can be controlled. As a result, a decrease of the efficiency of conversion to fluorescent light in a portion of fluorescent layer 12b can be prevented and the fluorescent light can be stabilized and easily obtained.
Fan 15 is arranged inside cover 10. A sirocco fan is used as fan 15, and fan 15 has an air supply port that supplies cooling air.
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Base 22b of lens holder 22 is formed in plate form that has an L-shaped cross section and is fixed to the bottom panel of lower cover 10b. Base 22b has upright wall 22c. Support unit 22a is provided at a position separated from the bottom panel of lower cover 10b of upright wall 22c. In addition, upright wall 22c is linked together with partition wall 19 of duct 16 and is formed as a part of partition wall 19.
Forming lens holder 22 as described hereinabove secures first air passage 23a through which cooling air flows between support unit 22a and the bottom panel of lower cover 10b and improves the ventilation characteristics of the cooling air. The obstruction of cooling air supplied from fan 15 by lens holder 22 can thus be prevented and the cooling air is able to flow smoothly along partition wall 19 of duct 16.
Support unit 22a of lens holder 22 supports the outer periphery of each of condensing lenses 13a, 13b, and 13c. Support unit 22a includes a plurality of second air passages 23b between each of the plurality of condensing lenses 13a, 13b, and 13c through which passes the cooling air that is supplied from fan 15. Due to the inclusion of second air passages 23b, support unit 22a does not obstruct the flow of cooling air that is supplied from fan 15 and allows the efficient cooling of fluorescent layer 12b.
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Heat sink 24 is linked to axle bearing 17b of rotational axis 17a that belongs to wheel motor 17. As shown in
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A propeller fan is used as fan 27. As shown in
The cooling air that is supplied from fan 27, after having cooled cooling unit 21b, passes by way of cooling unit 21b and is blown against heat sink 24. In this way, cooling unit 21b and heat sink 24 can be efficiently cooled by using the cooling air that is supplied from one fan 27, and cooling structure 11 is thus simplified.
Although a construction was adopted in the present exemplary embodiment in which cooling air that has passed through cooling unit 21b of heat exchanger 21 is blown against heat sink 24, the present exemplary embodiment is not limited to this form. As a modification, a configuration may of course be adopted in which cooling air that has passed through heat sink 24 is blown against cooling unit 21b, or in which cooling air is caused to flow between heat sink 24 and cooling unit 21b.
In the first optical path of illumination optical system 3, laser light that is emitted from laser diode 8 of first laser light source 6 is condensed by condensing lens 31, as shown in
On the second optical path of illumination optical system 3, the laser light that is emitted from laser diode 8 of second laser light source 7 is condensed by condensing lens 41, as shown in
Light that is emitted from light tunnel 44 is condensed by condensing lens 45. The light that has been condensed by condensing lens 45 is irradiated into dichroic mirror 46. Dichroic mirror 46 reflects light that has a blue wavelength and transmits light of wavelengths that are longer than a green wavelength. The blue laser light that is reflected by dichroic mirror 46 passes through condensing lenses 13a, 13b, and 13c and is irradiated into fluorescent layer 12b of fluorescent wheel 12. The fluorescent material is excited by the blue laser light and radiates yellow fluorescent light.
The yellow light that is radiated from the fluorescent material is condensed by condensing lenses 13a, 13b, and 13c and irradiated into dichroic mirror 46. The yellow light that is irradiated into dichroic mirror 46 is transmitted through dichroic mirror 46 and irradiated into condensing lens 47. The yellow light that is irradiated into condensing lens 47 is irradiated into dichroic mirror 35. The yellow light that is irradiated into dichroic mirror 35 is reflected by dichroic mirror 35 and irradiated into condensing lens 36.
In image generation optical system 4 that is provided in projection display apparatus 1, light that has been emitted from condensing lens 36 of illumination optical system 3 is irradiated into light tunnel 51, as shown in
The light that has been separated in color prism 57 is irradiated into DMDs (Digital Mirror Devices) that serve as image elements that modulate this light with an image signal. The green light that was separated by color prism 57 is irradiated into green light DMD 58. Similarly, the red light that was separated by color prism 57 is irradiated into red light DMD (not shown), and the blue light that was separated by color prism 57 is irradiated into blue light DMD (not shown). As a modification, a liquid crystal panel (LCD) may be used as an image element in place of the DMDs.
DMD 58 has a multiplicity of micromirrors arrayed in matrix form, each micromirror corresponding to a picture element of the image that is to be projected. The micromirrors are configured so as to allow adjustment of the angle of each micromirror. Light that is irradiated into a micromirror that has a certain angle is reflected toward projection lens 59. Accordingly, green light, red light, and blue light that are reflected at each DMD are irradiated into color prism 57 and synthesized in color prism 57. The light that is synthesized at color prism 57 passes through TIR prism 56 and projection lens 59 and is then projected upon a projection surface such as a screen.
The operation by which fluorescent wheel 12 is cooled by fan 15 and duct 16 is next described with regard to cooling structure 11 of an illumination optical system that has been configured as described hereinabove.
Cooling air that is supplied from fan 15 flows inside duct 16 along partition wall 19 and is blown against both surfaces of substrate 12a of fluorescent wheel 12. The cooling air that is blown against the surface on the side of fluorescent layer 12b of fluorescent wheel 12 passes through air passages 23 of lens holder 22 and the space on the peripheral side of support unit 22a of lens holder 22 and flows smoothly along the surface on the fluorescent layer 12b side. In this way, cooling air supplied from fan 15 is guided along duct 16 and effectively cools the entirety of fluorescent wheel 12.
Cooling air that has cooled fluorescent layer 12b of fluorescent wheel 12 further flows along partition wall 19 and is cooled by heat exchanger 21. The air that has been cooled by heat exchanger 21 is discharged from duct 16, passes through the interior of illumination optical system 3, and circulates to fan 15 as shown by the arrow in
Cooling unit 21b of heat exchanger 21 is further cooled by the cooling air supplied from fan 27. Heat sink 24 is cooled by the cooling air that has cooled cooling unit 21b. Fluorescent layer 12b of fluorescent wheel 12 is cooled by the cooling of heat sink 24.
Compared to a configuration in which a fan is simply arranged in the vicinity of the fluorescent wheel inside the case of a projection display apparatus, the present exemplary embodiment enables cooling of air surrounding fluorescent wheel 12 by the cooling air that is guided along duct 16. In this way, the fluorescent material can be efficiently cooled.
In addition, because lens holder 22 that is arranged inside duct 16 has air passages 23, obstruction of the flow of cooling air supplied from fan 15 is prevented. The cooling efficiency of the fluorescent material is increased by the combined effect of each of these configurations for increasing the ventilation characteristics of cooling air.
As described hereinabove, cooling structure 11 of the illumination optical system of the first exemplary embodiment is provided with duct 16 that guides cooling air supplied from fan 15 to fluorescent wheel 12, whereby the temperature of air surrounding fluorescent wheel 12 is lowered by the cooling air that is guided along duct 16, enabling efficient cooling of the fluorescent material. As a result, cooling structure 11 is able to improve the cooling efficiency of the fluorescent material and prevent a decrease in the illuminance of the light that is emitted from illumination optical system 3.
In addition, lens holder 22, by incorporating spaces between support unit 22a and the bottom panel of lower cover 10b, prevents obstruction of the flow of cooling air supplied from fan 15 and enables adequate flow of the cooling air to the surface of fluorescent wheel 12 on the side of fluorescent layer 12b. Lens holder 22 further, by incorporating air passages 23, prevents obstruction of the flow of cooling air supplied from fan 15 and enables the smooth flow of cooling air to the surface of fluorescent wheel 12 on the side of fluorescent layer 12b. As a result, the effect of cooling the fluorescent material can be increased.
Finally, due to the incorporation of heat exchanger 21, cooling structure 11 is capable of both preventing an increase in the temperature of the cooling air that is supplied by fan 15, and further, efficiently cooling fluorescent wheel 12. In addition, cooling structure 11, by incorporating heat is capable of sink 24, is capable of discharging the heat of fluorescent wheel 12 to the outside of duct 16.
A second illumination optical system cooling structure is next described. For the sake of convenience, constituent elements in the illumination optical system that is provided with the cooling structure of the second exemplary embodiment that are identical to those of the illumination optical system of the first exemplary embodiment are given the same reference numbers as in the first exemplary embodiment, and redundant explanation is omitted.
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In cooling structure 61 of the illumination optical system of the second exemplary embodiment as described hereinabove, the cooling air that is supplied from first fan 67a flows through one space of the internal space of duct 66 that is divided by dividing wall 69 and is guided to the surface of fluorescent wheel 12 on the side on which fluorescent layer 12b is formed. Similarly, cooling air that is supplied from second fan 67b flows through the other space of the internal space of duct 66 that is partitioned by dividing wall 69 and is guided to the other surface of fluorescent wheel 12. In this way, each cooling air flow is guided smoothly to the two sides of fluorescent wheel 12 in the present exemplary embodiment.
According to cooling structure 61 of the illumination optical system of the second exemplary embodiment, the provision of dividing wall 69 and first and second fans 67a and 67b enables the cooling air to be smoothly guided to both sides of fluorescent wheel 12 and can obtain a further increase of the cooling efficiency of the fluorescent material.
Further, although the cooling structure of the illumination optical system according to the present invention was used in an illumination optical system that is provided with a fluorescent wheel, the cooling structure may also be used in another illumination optical system as necessary. The present invention may also be used in an illumination optical system that uses a color wheel that has a color filter into which light from a light source is irradiated or in another illumination optical system that uses a fluorescent material of fixed construction.
Although the present invention has been described with reference to exemplary embodiments, the present invention is not limited to the above-described exemplary embodiments. The configuration and details of the present invention are open to various modifications within the scope of the present invention that will be clear to one of ordinary skill in the art.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2014/061955 | 4/30/2014 | WO | 00 |
